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Tso WWY, Chan KL, Lee TMC, Rao N, Lee SL, Jiang F, Chan SHS, Wong WHS, Wong RS, Tung KTS, Yam JC, Liu APY, Chua GT, Rosa Duque JS, Lam ALN, Yip KM, Leung LK, Wang Y, Sun J, Wang G, Chan GCF, Wong ICK, Ip P. Mental health & maltreatment risk of children with special educational needs during COVID-19. Child Abuse Negl 2022; 130:105457. [PMID: 35033372 PMCID: PMC8743505 DOI: 10.1016/j.chiabu.2021.105457] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/19/2021] [Revised: 12/15/2021] [Accepted: 12/20/2021] [Indexed: 05/16/2023]
Abstract
BACKGROUND Children with special educational needs (SEN) are more vulnerable during the COVID-19 pandemic with risk of poor mental wellbeing and child maltreatment. OBJECTIVE To examine the impact of COVID-19 on the mental health of children with SEN and their maltreatment risk. PARTICIPANTS AND SETTING 417 children with SEN studying at special schools and 25,427 children with typical development (TD) studying at mainstream schools completed an online survey in April 2020 in Hong Kong during school closures due to COVID-19. METHOD Emotional/behavioural difficulties, quality of life and parental stress of children with SEN were compared with typically developed children using mixed effect model. Linear regression analyses were performed to explore factors associated with child emotional/behavioural difficulties and parental stress during the pandemic. Chi-square test was performed to detect the differences in maltreatment risk before and during COVID-19. RESULTS Children with SEN had significantly poorer overall quality of life (68.05 vs 80.65, p < 0.01). 23.5% of children had at least one episode of severe physical assault and 1.9% experienced very severe physical assault during COVID-19. Rates of physical assault increased significantly (59.8% vs. 71.2% p < 0.001) while children with mental disorders had increased risk of severe physical assault comparing to those without mental disorders (RR = 1.58, ꭓ2 = 5.19 p = 0.023). CONCLUSION Children with SEN had poorer mental health than typically developed children during the COVID-19 pandemic. Maltreatment risk for children with SEN is higher in comparison to pre-COVID-19 era. Surveillance of child maltreatment, continuity of medical and rehabilitation care to support children with SEN are essential during a disease pandemic.
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Affiliation(s)
- Winnie W Y Tso
- Department of Paediatrics and Adolescent Medicine, LKS Faculty of Medicine, The University of Hong Kong, Pokfulam, Hong Kong; State Key Laboratory of Brain and Cognitive Sciences, The University of Hong Kong, Pokfulam, Hong Kong
| | - Ko Ling Chan
- Department of Applied Social Sciences, The Hong Kong Polytechnic University, Hong Kong.
| | - Tatia M C Lee
- State Key Laboratory of Brain and Cognitive Sciences, The University of Hong Kong, Pokfulam, Hong Kong; Laboratory of Neuropsychology, The University of Hong Kong, Pokfulam, Hong Kong
| | - Nirmala Rao
- Faculty of Education, The University of Hong Kong, Pokfulam, Hong Kong
| | - S L Lee
- Department of Paediatrics and Adolescent Medicine, LKS Faculty of Medicine, The University of Hong Kong, Pokfulam, Hong Kong
| | - Fan Jiang
- Department of Developmental and Behavioral Pediatrics, Pediatric Translational Medicine Institute, National Children's Medical Center-Shanghai Children's Medical Center, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Sophelia H S Chan
- Department of Paediatrics and Adolescent Medicine, LKS Faculty of Medicine, The University of Hong Kong, Pokfulam, Hong Kong
| | - Wilfred H S Wong
- Department of Paediatrics and Adolescent Medicine, LKS Faculty of Medicine, The University of Hong Kong, Pokfulam, Hong Kong
| | - Rosa S Wong
- Department of Paediatrics and Adolescent Medicine, LKS Faculty of Medicine, The University of Hong Kong, Pokfulam, Hong Kong
| | - Keith T S Tung
- Department of Paediatrics and Adolescent Medicine, LKS Faculty of Medicine, The University of Hong Kong, Pokfulam, Hong Kong
| | - Jason C Yam
- Department of Ophthalmology and Visual Sciences, The Chinese University of Hong Kong, Hong Kong
| | - Anthony P Y Liu
- Department of Paediatrics and Adolescent Medicine, LKS Faculty of Medicine, The University of Hong Kong, Pokfulam, Hong Kong
| | - Gilbert T Chua
- Department of Paediatrics and Adolescent Medicine, LKS Faculty of Medicine, The University of Hong Kong, Pokfulam, Hong Kong
| | - Jaime S Rosa Duque
- Department of Paediatrics and Adolescent Medicine, LKS Faculty of Medicine, The University of Hong Kong, Pokfulam, Hong Kong
| | - Almen L N Lam
- Department of Paediatrics and Adolescent Medicine, LKS Faculty of Medicine, The University of Hong Kong, Pokfulam, Hong Kong
| | - K M Yip
- Department of Paediatrics and Adolescent Medicine, LKS Faculty of Medicine, The University of Hong Kong, Pokfulam, Hong Kong
| | - L K Leung
- Department of Paediatrics and Adolescent Medicine, LKS Faculty of Medicine, The University of Hong Kong, Pokfulam, Hong Kong
| | - Yuliang Wang
- Department of Paediatrics and Adolescent Medicine, LKS Faculty of Medicine, The University of Hong Kong, Pokfulam, Hong Kong
| | - Jin Sun
- Department of Early Childhood Education, The Education University of Hong Kong, Hong Kong
| | - Guanghai Wang
- Department of Developmental and Behavioral Pediatrics, Pediatric Translational Medicine Institute, National Children's Medical Center-Shanghai Children's Medical Center, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Godfrey C F Chan
- Department of Paediatrics and Adolescent Medicine, LKS Faculty of Medicine, The University of Hong Kong, Pokfulam, Hong Kong
| | - Ian C K Wong
- Centre for Safe Medication Practice and Research, Department of Pharmacology and Pharmacy, LKS Faculty of Medicine, The University of Hong Kong, Pokfulam, Hong Kong; Research Department of Practice and Policy, University College London School of Pharmacy, London, United Kingdom
| | - Patrick Ip
- Department of Paediatrics and Adolescent Medicine, LKS Faculty of Medicine, The University of Hong Kong, Pokfulam, Hong Kong.
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Li Q, Tan YQ, Cheung KK, Chiu-Leung LC, Leung LK. The mycoestrogen zeranol at high dosage antagonizes transient receptor potential channel activities in 3T3 L1 cells. Toxicol Lett 2021; 344:18-25. [PMID: 33689779 DOI: 10.1016/j.toxlet.2021.03.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2020] [Revised: 03/03/2021] [Accepted: 03/04/2021] [Indexed: 11/24/2022]
Abstract
Recent findings have revealed that exposure to environmental contaminants may result in obesity and pose a health threat to the general public. As the activity of transient receptor potential channels (TRPs) plays a permissive role in adipogenesis, the interactions between TRPs and some food pollutants, i.e. bisphenol A, di (2-ethylhexyl) phthalate, zearalenone, and zeranol at 10 μM were investigated in the present study. TRP-V1,-V3, -C4 and -C6 are reported to be differentially expressed in the adipocyte differentiation, and immunoblotting was performed to quantify changes in these TRPs affected by the pollutants. Our result indicated that the mycoestrogen zeranol or α-zearalanol suppressed the expression of the V1 and C6 isoforms. Subsequently, confocal microscopy was used to measure the calcium inflow repressed by zeranol from 0.1 μM to 10 μM. Oil Red O staining was used to determine the differentiation of 3T3 L1 preadipocytes. Zeranol could suppress the expression of TRP-V1 and -C6 protein and inhibit the associated flow of calcium into the cytosol of 3T3 L1 cells. Its IC50 value for inhibiting calcium inflow stimulated by 40 μM capsaicin or 10 μM GSK1702934A was estimated to be around 6 μM. Reduced TRP-V1 or -C6 activity might result in promoting adipogenesis. In conclusion, this study demonstrated that zeranol could potentiate fat cell differentiation through antagonizing TRP-V1 and -C6 activities.
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Affiliation(s)
- Qing Li
- Biochemistry Programme, School of Life Sciences, School of Life Sciences, Faculty of Science, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong
| | - Yan Qin Tan
- Food and Nutritional Sciences Programme, School of Life Sciences, Faculty of Science, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong
| | - Kam Kuen Cheung
- Food and Nutritional Sciences Programme, School of Life Sciences, Faculty of Science, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong
| | - Leo C Chiu-Leung
- Marine Science, School of Life Sciences, Faculty of Science, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong
| | - Lai K Leung
- Food and Nutritional Sciences Programme, School of Life Sciences, Faculty of Science, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong; Biochemistry Programme, School of Life Sciences, School of Life Sciences, Faculty of Science, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong.
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Tso WYW, Hui SK, Lee TMC, Liu APY, Ip P, Cheng K, Fong D, Chang D, Ho FKW, Yip KM, Ku D, Cheuk DKL, Luk CW, Shing MK, Leung LK, Khong PL, Chan GCF. QOL-25. MICROSTRUCTURAL BRAIN CHANGES ASSOCIATED WITH NEUROCOGNITIVE AND FUNCTIONAL OUTCOMES OF INTRACRANIAL GERM CELL TUMUOR SURVIVORS – A DIFFUSIONAL KURTOSIS IMAGING STUDY. Neuro Oncol 2020. [PMCID: PMC7715703 DOI: 10.1093/neuonc/noaa222.687] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Abstract
BACKGROUND
Childhood intracranial germ cell tumour (iGCT) survivors are prone to radiotherapy-related neurotoxicity which can lead to neurocognitive dysfunction. Diffusion kurtosis imaging (DKI) is a MRI technique that quantifies microstructural changes in the grey and white matter of the brain. This study aims to investigate the associations between MR-DKI metrics, the cognitive and functional outcomes of childhood iGCT survivors.
METHOD
20 childhood iGCT survivors who had received cranial radiotherapy were recruited. DKI parameters were determined for iGCT survivors and 18 control subjects. Neurocognitive assessment using the Hong Kong Wechsler Intelligence Scales for Children (HKWISC)/ Wechsler Adult Intelligence Scale – Revised (WAIS-R) and functional assessment using the Lansky/ Karnofsky performance scales were performed for GCT survivors.
RESULTS
There were significant negative correlation between the IQ scores and the mean diffusivity (MD) in multiple white matter regions of iGCT survivors including: anterior limb of internal capsule, superior fronto-occipital fasciculus, anterior corona radiata, uncinate fasciculus, cingulum and hippocampus. Mean kurtosis (MK) values of the superior fronto-occipital fasciculus were positively correlated with IQ scores. For grey matter, the MD of the olfactory, insula, caudate, heschl gyrus, parahippocampal gyrus, hippocampus, anterior cingulum, frontal inferior operculum, middle and superior temporal gyrus, middle and superior frontal orbital gyri, cuneus and precentral gyrus were negatively correlated with IQ scores. Most of the microstructural changes with associated functional impairment were white matter regions.
CONCLUSION
Our study identified vulnerable brain regions with significant white and grey matter microstructural changes that were associated with impaired cognitive function or deficits in physical functioning.
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Affiliation(s)
- Wan-Yee Winnie Tso
- Department of Paediatrics & Adolescent Medicine, LKS Faculty of Medicine, University of Hong Kong, Hong Kong, Hong Kong
| | - Sai Kam Hui
- Department of Diagnostic Radiology, LKS Faculty of Medicine, University of Hong Kong, Hong Kong, Hong Kong
| | - Tatia Mei Chun Lee
- State Key Laboratory of Brain and Cognitive Sciences, The University of Hong Kong, Hong Kong, Hong Kong
| | - Anthony Pak Yin Liu
- Department of Paediatrics & Adolescent Medicine, LKS Faculty of Medicine, University of Hong Kong, Hong Kong, Hong Kong
| | - Patrick Ip
- Department of Paediatrics & Adolescent Medicine, LKS Faculty of Medicine, University of Hong Kong, Hong Kong, Hong Kong
| | - Kevin Cheng
- Department of Neurosurgery, Queen Mary Hospital, Hong Kong, Hong Kong
| | - Daniel Fong
- Department of Nursing, LKS Faculty of Medicine, University of Hong Kong, Hong Kong, Hong Kong
| | - Dorita Chang
- State Key Laboratory of Brain and Cognitive Sciences, The University of Hong Kong, Hong Kong, Hong Kong
| | - Frederick K W Ho
- Institute of Health and Wellbeing, University of Glasgow, Glasgow, United Kingdom
| | - Ka Man Yip
- Department of Paediatrics & Adolescent Medicine, LKS Faculty of Medicine, University of Hong Kong, Hong Kong, Hong Kong
| | - Dennis Ku
- Hong Kong Children’s Hospital, Hong Kong, Hong Kong
| | | | | | | | - L K Leung
- Department of Paediatrics & Adolescent Medicine, LKS Faculty of Medicine, University of Hong Kong, Hong Kong, Hong Kong
| | - Pek Lan Khong
- Department of Diagnostic Radiology, LKS Faculty of Medicine, University of Hong Kong, Hong Kong, Hong Kong
| | - Godfrey Chi Fung Chan
- Department of Paediatrics & Adolescent Medicine, LKS Faculty of Medicine, University of Hong Kong, Hong Kong, Hong Kong
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Tan YQ, Li Q, Wang L, Chiu-Leung LC, Leung LK. The livestock growth-promoter zeranol facilitates GLUT4 translocation in 3T3 L1 adipocytes. Chemosphere 2020; 253:126772. [PMID: 32464760 DOI: 10.1016/j.chemosphere.2020.126772] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/14/2020] [Revised: 03/23/2020] [Accepted: 04/08/2020] [Indexed: 06/11/2023]
Abstract
Zeranol is an approved but controversial growth-promoting agent for livestock in North America. It is a mycotoxin metabolite secreted by the Fusarium family fungi. The regulatory bodies in this region have established the acceptable daily intake and exposure below the level would not significantly increase the health risk for humans. However, their European counterparts have yet to establish an acceptable level and do not permit the use of this agent in farm animals. Given the growth-promoting ability of zeranol, its effect on energy metabolism was investigated in the current study. Our results indicated that zeranol could induce glucose transporter type 4 (GLUT4) expression in 3T3 L1 cells at 10 μM and initiate the translocation of the glucose transporter to the membrane as assayed by confocal microscopy. The translocation was likely triggered by the increase of GLUT4 and p-Akt. The insulin signal transduction pathway of glucose translocation was analyzed by Western blot analysis. Since no increase in the phosphorylated insulin receptor substrate in zeranol-treated cells was evidenced, the increased p-Akt and GLUT4 amount should be the mechanism dictating the GLUT4 translocation. In summary, this study showed that zeranol could perturb glucose metabolism in differentiated 3T3 L1 adipocytes. Determining the growth-promoting mechanism is crucial to uncover an accepted alternative to the general public.
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Affiliation(s)
- Yan Qin Tan
- Food and Nutritional Sciences Programme, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong
| | - Qing Li
- Department of Biochemistry, School of Life Sciences, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong
| | - Lin Wang
- Cell and Molecular Biology Programme, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong
| | - Leo C Chiu-Leung
- Marine Science, School of Life Sciences, Faculty of Science, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong
| | - Lai K Leung
- Food and Nutritional Sciences Programme, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong; Department of Biochemistry, School of Life Sciences, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong.
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5
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Tan YQ, Kwan HY, Yao X, Leung LK. The activity of transient receptor potential channel C‐6 modulates the differentiation of fat cells. FASEB J 2019; 33:6526-6538. [DOI: 10.1096/fj.201801518rr] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Affiliation(s)
- Yan Qin Tan
- School of Life SciencesFaculty of ScienceBaptist University Hong Kong China
| | - Hiu Yee Kwan
- School of Chinese MedicineBaptist University Hong Kong China
| | - Xiaoqiang Yao
- School of Biomedical SciencesFaculty of MedicineThe Chinese University of Hong Kong Hong Kong China
| | - Lai K. Leung
- School of Life SciencesFaculty of ScienceBaptist University Hong Kong China
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Wong TY, Tan YQ, Lin SM, Leung LK. Co-administrating apigenin in a high-cholesterol diet prevents hypercholesterolaemia in golden hamsters. J Pharm Pharmacol 2018; 70:1253-1261. [DOI: 10.1111/jphp.12953] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2017] [Accepted: 05/28/2018] [Indexed: 01/23/2023]
Abstract
Abstract
Objectives
Hypercholesterolaemia is a major risk factor for developing atherosclerosis. Increased consumption of fruits and vegetables is recommended to hypercholesterolaemic patients. In this study, the hypocholesterolaemic effect of apigenin and luteolin was evaluated in a hamster model.
Methods
Hamsters were put on a high-cholesterol diet for 9 weeks, and apigenin or luteolin was administered in the diet at 60 and 300 ppm.
Key findings
Both apigenin and luteolin supplementations could attenuate the aorta plaque formation by 30% and 20%, respectively. Apigenin-fed hamsters at both dosages displayed a 1.5-fold increase in hepatic Ldlr expression and a 40% reduction in non-HDL cholesterol level as compared with those in the control fed a high-cholesterol (HC) diet. Besides, faecal elimination of cholesterol was facilitated by 20% in the hamsters with high apigenin consumption. Suppressing the expression of the cholesterol transporter ncp1l1 in the intestinal mucosa could block the cholesterol absorption and promote its elimination. The differential regulations of ncp1l1 and Ldlr appeared to be the underlying hypocholesterolaemic mechanism of apigenin in this model system. Luteolin supplementation, on the other hand, had no effect on the blood cholesterol.
Conclusions
This study illustrated that dietary administration of apigenin attenuated HC feeding-induced hypercholesterolemia in hamsters.
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Affiliation(s)
- Tsz Yan Wong
- Food and Nutritional Sciences Programme, School of Life Sciences, Faculty of Science, The Chinese University of Hong Kong, Shatin, Hong Kong
| | - Yan Qin Tan
- Food and Nutritional Sciences Programme, School of Life Sciences, Faculty of Science, The Chinese University of Hong Kong, Shatin, Hong Kong
| | - Shu-mei Lin
- Department of Food Science, National Chiayi University, Chiayi City, Taiwan
| | - Lai K Leung
- Food and Nutritional Sciences Programme, School of Life Sciences, Faculty of Science, The Chinese University of Hong Kong, Shatin, Hong Kong
- Biochemistry Programme, School of Life Sciences, Faculty of Science, The Chinese University of Hong Kong, Shatin, Hong Kong
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7
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Tan YQ, Chiu-Leung LC, Lin SM, Leung LK. The citrus flavonone hesperetin attenuates the nuclear translocation of aryl hydrocarbon receptor. Comp Biochem Physiol C Toxicol Pharmacol 2018; 210:57-64. [PMID: 29763690 DOI: 10.1016/j.cbpc.2018.05.007] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/07/2018] [Revised: 05/03/2018] [Accepted: 05/10/2018] [Indexed: 02/06/2023]
Abstract
The environmental polycyclic aromatic hydrocarbons (PAH) and dioxins are carcinogens and their adverse effects have been largely attributed to the activation of AhR. Hesperetin is a flavonone found abundantly in citrus fruits and has been shown to be a biologically active agent. In the present study, the effect of hesperetin on the nuclear translocation of AhR and the downstream gene expression was investigated in MCF-7 cells. Confocal microscopy indicated that 7, 12-dimethylbenz[α]anthracene (DMBA) or 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) -induced nuclear translocation of AhR was deterred by hesperetin treatment. The reduced nuclear translocation could also be observed in Western analysis. Reporter-gene assay further illustrated that the induced XRE transactivation was weakened by the treatment of hesperetin. Quantitative reverse transcriptase-polymerase chain reaction (RT-PCR) assay demonstrated that the gene expressions of CYP1A1, 1A2, and 1B1 followed the same pattern of AhR translocation. These results suggested that hesperetin counteracted AhR transactivation and suppressed the downstream gene expression.
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MESH Headings
- 9,10-Dimethyl-1,2-benzanthracene/antagonists & inhibitors
- 9,10-Dimethyl-1,2-benzanthracene/toxicity
- Active Transport, Cell Nucleus/drug effects
- Antineoplastic Agents, Phytogenic/metabolism
- Basic Helix-Loop-Helix Transcription Factors/antagonists & inhibitors
- Basic Helix-Loop-Helix Transcription Factors/metabolism
- Breast Neoplasms/chemically induced
- Breast Neoplasms/metabolism
- Breast Neoplasms/pathology
- Breast Neoplasms/prevention & control
- Carcinogens, Environmental/chemistry
- Carcinogens, Environmental/toxicity
- Cytochrome P-450 CYP1A1/antagonists & inhibitors
- Cytochrome P-450 CYP1A1/chemistry
- Cytochrome P-450 CYP1A1/genetics
- Cytochrome P-450 CYP1A1/metabolism
- Cytochrome P-450 CYP1A2/chemistry
- Cytochrome P-450 CYP1A2/genetics
- Cytochrome P-450 CYP1A2/metabolism
- Cytochrome P-450 CYP1B1/antagonists & inhibitors
- Cytochrome P-450 CYP1B1/chemistry
- Cytochrome P-450 CYP1B1/genetics
- Cytochrome P-450 CYP1B1/metabolism
- Dietary Supplements
- Down-Regulation
- Female
- Gene Expression Regulation, Neoplastic/drug effects
- Genes, Reporter/drug effects
- Hesperidin/metabolism
- Humans
- MCF-7 Cells
- Microscopy, Confocal
- Neoplasm Proteins/antagonists & inhibitors
- Neoplasm Proteins/genetics
- Neoplasm Proteins/metabolism
- Polychlorinated Dibenzodioxins/antagonists & inhibitors
- Polychlorinated Dibenzodioxins/chemistry
- Receptors, Aryl Hydrocarbon/antagonists & inhibitors
- Receptors, Aryl Hydrocarbon/metabolism
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Affiliation(s)
- Yan Qin Tan
- Food and Nutritional Sciences Programme, School of Life Sciences, Faculty of Science, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong
| | | | - Shu-Mei Lin
- Department of Food Science, National Chiayi University, Chiayi City, Taiwan
| | - Lai K Leung
- Food and Nutritional Sciences Programme, School of Life Sciences, Faculty of Science, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong.
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Honjo K, Hamada T, Yoshimura T, Yokoyama S, Yamada S, Tan YQ, Leung LK, Nakamura N, Ohi Y, Higashi M, Tanimoto A. PCP4/PEP19 upregulates aromatase gene expression via CYP19A1 promoter I.1 in human breast cancer SK-BR-3 cells. Oncotarget 2018; 9:29619-29633. [PMID: 30038708 PMCID: PMC6049867 DOI: 10.18632/oncotarget.25651] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2017] [Accepted: 05/23/2018] [Indexed: 12/24/2022] Open
Abstract
The Purkinje cell protein 4/peptide 19 (PCP4/PEP19) is a novel breast cancer cell expressing peptide, originally found in the neural cells as an anti-apoptotic factor, could inhibit cell apoptosis and enhance cell migration and invasion in human breast cancer cell lines. The expression of PCP4/PEP19 is induced by estrogens in estrogen receptor-positive (ER+) MCF-7 cells but also highly expressed in ER- SK-BR-3 cells. In this study, we investigated the effects of PCP4/PEP19 on aromatase gene expression in MCF-7 and SK-BR-3 human breast cancer cells. In SK-BR-3 cells but not in MCF-7 cells, PCP4/PEP19 knockdown by siRNA silencing decreased the aromatase expression in gene transcriptional level. When PCP4/PEP19 was overexpressed by CMV promoter-driven PCP4/PEP19 expressing plasmid transfection, aromatase gene transcription increased in SK-BR-3 cells. This aromatase gene transcription is mainly mediated through promoter region PI.1, which is usually active in the placental tissue but not in the breast cancer tissue. These results indicate a new function of PCP4/PEP19 that would enhance aromatase gene upregulation to supply estrogens in heterogeneous cancer microenvironment.
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Affiliation(s)
- Kie Honjo
- Department of Oral Surgery, Kagoshima University Graduate School of Medical and Dental Sciences, Kagoshima, Japan
| | - Taiji Hamada
- Department of Pathology, Kagoshima University Graduate School of Medical and Dental Sciences, Kagoshima, Japan
| | - Takuya Yoshimura
- Department of Oral Surgery, Kagoshima University Graduate School of Medical and Dental Sciences, Kagoshima, Japan
| | - Seiya Yokoyama
- Department of Pathology, Kagoshima University Graduate School of Medical and Dental Sciences, Kagoshima, Japan
| | - Sohsuke Yamada
- Department of Pathology, Kagoshima University Graduate School of Medical and Dental Sciences, Kagoshima, Japan.,Department of Pathology and Laboratory Medicine, Kanazawa Medical University, Ishikawa, Japan
| | - Yan-Qin Tan
- Faculty of Science, School of Life Sciences, Food and Nutritional Science Programme, The Chinese University of Hong Kong, Shatin, Hong Kong
| | - Lai K Leung
- Faculty of Science, School of Life Sciences, Food and Nutritional Science Programme, The Chinese University of Hong Kong, Shatin, Hong Kong
| | - Norifumi Nakamura
- Department of Oral Surgery, Kagoshima University Graduate School of Medical and Dental Sciences, Kagoshima, Japan
| | - Yasuyo Ohi
- Department of Pathology, Sagara Hospital, Social Medical Corporation Hakuaikai, Kagoshima, Japan
| | - Michiyo Higashi
- Department of Pathology, Kagoshima University Graduate School of Medical and Dental Sciences, Kagoshima, Japan
| | - Akihide Tanimoto
- Department of Pathology, Kagoshima University Graduate School of Medical and Dental Sciences, Kagoshima, Japan
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Wong TY, Tan YQ, Lin SM, Leung LK. Apigenin and luteolin display differential hypocholesterolemic mechanisms in mice fed a high-fat diet. Biomed Pharmacother 2017; 96:1000-1007. [DOI: 10.1016/j.biopha.2017.11.131] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2017] [Revised: 11/16/2017] [Accepted: 11/27/2017] [Indexed: 12/21/2022] Open
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10
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Tan W, Zhu Z, Ye L, Leung LK. Methylation dictates PI.f-specific CYP19 transcription in human glial cells. Mol Cell Endocrinol 2017; 452:131-137. [PMID: 28559115 DOI: 10.1016/j.mce.2017.05.029] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/13/2017] [Revised: 05/24/2017] [Accepted: 05/24/2017] [Indexed: 01/31/2023]
Abstract
CYP19 is the single copy gene encoding for the estrogen synthetic enzyme aromatase. Alternate splicing of the promoter is the regulatory mechanism of this gene. In the brain, estrogen is synthesized in neuronal and glial cells and the gene is mainly regulated by the alternate promoter PI.f. The hormone produced in this vicinity has been associated with maintaining normal brain functions. Previously, epigenetic regulation has been shown in the promoters PII and I.3 of CYP19 in adipocytes. In the present study, the methylation of PI.f in CYP19 was examined in glial cells. Treatment of the hypomethylating agent 5-aza-2'deoxycytidine increased CYP19 mRNA species in U87 MG cells while little changes were observed in the other glia cell lines. As PI.f is also chiefly used in T98G cells with high expression of CYP19, the methylation statuses of the promoter in these two cell models were compared. Our results showed that treating U87 MG cells with 10 μM 5-aza-2'deoxycytidine significantly induced a ∼10-fold increase in CYP19 transcription and ∼80% increase in aromatase activity. In contrast, the same treatment did not change either endpoint in T98G cells. Further investigation illustrated the CpGs in PI.f were differentially methylated in the two cell lines; 63% and 37% of the 14 CpG sites were methylated in U87 MG and T98G cells respectively. In conclusion, this study illustrated that the brain-specific PI.f derived CYP19 expression can be regulated by DNA methylation.
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Affiliation(s)
- Wenjuan Tan
- Biochemistry Programme, School of Life Sciences, Faculty of Science, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong
| | - Zhiping Zhu
- State Key Laboratory of Reproductive Medicine, Nanjing Medical University, Nanjing 211166, China
| | - Lan Ye
- State Key Laboratory of Reproductive Medicine, Nanjing Medical University, Nanjing 211166, China.
| | - Lai K Leung
- Biochemistry Programme, School of Life Sciences, Faculty of Science, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong; Food and Nutritional Sciences Programme, School of Life Sciences, Faculty of Science, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong.
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11
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Zhu Y, Tan YQ, Leung LK. Exposure to 2,2',4,4'-tetrabromodiphenyl ether at late gestation modulates placental signaling molecules in the mouse model. Chemosphere 2017; 181:289-295. [PMID: 28448910 DOI: 10.1016/j.chemosphere.2017.04.089] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/06/2017] [Revised: 04/19/2017] [Accepted: 04/20/2017] [Indexed: 06/07/2023]
Abstract
Polybrominated diphenyl ethers (PBDEs) are flame retardants generally employed in manufacturing household items. Surface water may remove and carry these chemicals to the drainage upon disposal of the items, and ultimately the chemicals enter our food chain. 2,2',4,4'-Tetrabromodiphenyl ether (BDE-47) is a PBDE congener commonly found in contaminated seafood. The placenta is the site of nutrient exchange and is responsible for reproductive hormone secretion during pregnancy. In the present study, pregnant ICR mice were given p.o. daily doses of BDE-47 at 0, 0.36, 3.6, 36 mg/kg for 4 days (from E13.5 to E16.5). Compared to the control group, increased rates of stillborn and low birth weight were observed in mice treated with 36 mg BDE-47/kg. Plasma testosterone and progesterone levels were reduced in mice treated with 36 mg BDE-47/kg. In addition, the group treated with 3.6 mg/kg of BDE-47 displayed decreased growth hormone (Gh) peptide expression in the placental tissue extracted at E17.5. As this peptide stimulates growth, the expression pattern might suggest compromised fetal development. Further analysis indicated that mitogen-activated protein kinases (MAPK) were activated in the placental tissue of the BDE-47-treatment groups. The activation of these signaling molecules might affect the hormonal and other physiological functions in the tissue.
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Affiliation(s)
- Yun Zhu
- Food and Nutritional Sciences Programme, School of Life Sciences, Faculty of Science, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong
| | - Yan Qin Tan
- Food and Nutritional Sciences Programme, School of Life Sciences, Faculty of Science, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong
| | - Lai K Leung
- Food and Nutritional Sciences Programme, School of Life Sciences, Faculty of Science, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong; Biochemistry Programme, School of Life Sciences, Faculty of Science, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong.
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12
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Zhu Y, Tan YQ, Wang CC, Leung LK. The flame retardant 2,2',4,4'-Tetrabromodiphenyl ether enhances the expression of corticotropin-releasing hormone in the placental cell model JEG-3. Chemosphere 2017; 174:499-505. [PMID: 28189027 DOI: 10.1016/j.chemosphere.2017.01.144] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/15/2016] [Revised: 01/23/2017] [Accepted: 01/30/2017] [Indexed: 06/06/2023]
Abstract
Polybrominated diphenyl ethers (PBDEs) are chemicals used as flame retardants in household products. After disposing of these items, PBDEs leach from the products by surface water. BDE-47 is a PBDE congener commonly isolated from contaminated food and is the most studied isomer. The placenta is the major source of hormones during pregnancy, and an elevated level of corticotrophin-releasing hormone (CRH) is associated with premature delivery. In the present study, we examined changes in the placental CRH expression under BDE-47 exposure in the JEG-3 cell model system. These placental cells are derived from human choriocarcinoma. Our result showed that this pollutant induced the CRH mRNA expression at 0.5 nM or above in the cells. A similar trend was observed when CRH peptide was determined by Western analysis in the cell lysates. As previous studies have shown the importance of signal transduction pathways in the gene regulation, the status of some protein kinases in the present study was investigated. The phosphorylated PKCα, JNK, and P38 were increased by the toxicant treatment, and administering the specific inhibitors could counteract the induced CRH expression. It appeared that the signaling transduction pathway of PKC was a significant contributor in the transcriptional regulation. Further study by using Electrophoretic Mobility Shift Assay suggested that AP-2 was the ultimate DNA-binding element for the initiation of gene transcription. Because an untimely increased CRH may compromise fetal development and induce preterm birth, the present study suggested that endocrine changes in pregnancy should be taken into consideration in the next assessment.
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Affiliation(s)
- Yun Zhu
- Food and Nutritional Sciences Programme, School of Life Sciences, Faculty of Science, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong
| | - Yan Qin Tan
- Food and Nutritional Sciences Programme, School of Life Sciences, Faculty of Science, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong
| | - Chi Chiu Wang
- Department of Obstetrics and Gynaecology, Li Ka Shing Institute of Health Sciences and School of Biomedical Sciences, Faculty of Medicine, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong
| | - Lai K Leung
- Food and Nutritional Sciences Programme, School of Life Sciences, Faculty of Science, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong; Biochemistry Programme, School of Life Sciences, Faculty of Science, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong.
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Zhu Y, Qin Tan Y, Leung LK. Assessing placental corticotrophin-releasing hormone disruption by hexestrol in a cell model. Environ Toxicol Pharmacol 2016; 48:197-202. [PMID: 27816005 DOI: 10.1016/j.etap.2016.10.003] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/01/2016] [Revised: 10/05/2016] [Accepted: 10/07/2016] [Indexed: 06/06/2023]
Abstract
Studies have shown that corticotrophin-releasing hormone (CRH) and relaxin are associated with early delivery. Our lab previously has shown the mycotoxin zeranol increases placental CRH expression. The mycotoxin is used in the farming industry to promote cattle growth, and some synthetic hormones are also used for the same purposes. In order to complete the picture of these growth promoting agents, we attempted to examine the synthetic hormones on the placental gene expression in the current study. Among the tested compounds, hexestrol induced the CRH mRNA and protein expression at 100nM in JEG-3 cells. As signal transduction pathways have been described in the transcriptional control previously, the activations of several protein kinases were determined. P38, PKCβ and JNK were activated upon hexestrol treatment. Since the P38-inhibitor SB203580 prevented hexestrol from inducing CRH in a subsequent experiment, P38 was likely involved in the transcriptional regulation. Electrophoretic mobility shift assay revealed an increase in the CRE binding activity in CRH promoter. This study showed that hexestrol exposure might be a concern for pregnant women.
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Affiliation(s)
- Yun Zhu
- Food and Nutritional Sciences Programme, School of Life Sciences, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong
| | - Yan Qin Tan
- Food and Nutritional Sciences Programme, School of Life Sciences, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong
| | - Lai K Leung
- Food and Nutritional Sciences Programme, School of Life Sciences, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong; Biochemistry Programme, School of Life Sciences, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong.
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Zhu Y, Tan YQ, Leung LK. Aflatoxin B1 disrupts transient receptor potential channel activity and increases COX-2 expression in JEG-3 placental cells. Chem Biol Interact 2016; 260:84-90. [PMID: 27818125 DOI: 10.1016/j.cbi.2016.11.002] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2016] [Revised: 10/05/2016] [Accepted: 11/01/2016] [Indexed: 02/06/2023]
Abstract
Aflatoxins are fungal metabolites which pose a major threat to food safety. Although these mycotoxins are established hepatocarcinogens, their effect on the reproductive organ is unknown. Transient Receptor Potential Channels (TRPs) are ubiquitously expressed in human tissues, including the placenta. These channels are associated with various functions in the placenta. The fetus and the placenta are especially sensitive to xenobiotic assault; therefore, exposure to the aflatoxins during gestation might lead to the undesirable outcome. Previously we have shown that aflatoxin B1 administered in late gestation may increase cox-2 expression in mouse placentae. In the present study, we examined the effect of aflatoxin B1 on COX-2 by using the placental cell model JEG-3 and the respective signaling pathway. In our result, COX-2 expression was induced by the mycotoxin administration. The intracellular calcium levels were also increased in cells by aflatoxin B1 treatment as little as 1 nM. Immunoblot result showed that some TRP expressions were elevated. As inflated intracellular calcium might activate MAPKs, the underlying signaling pathway was investigated. With the help of TRP-specific inhibitors, the mycotoxin appeared to increase the expression of TRPC-3 and activate PKCβ and ERK. The significance of COX-2 in pregnancy has been well established. Exposure to this mycotoxin may perturb the physiological processes dictated by COX-2 in pregnancy.
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Affiliation(s)
- Yun Zhu
- Food and Nutritional Sciences Programme, School of Life Sciences, Faculty of Science, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong
| | - Yan Qin Tan
- Food and Nutritional Sciences Programme, School of Life Sciences, Faculty of Science, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong
| | - Lai K Leung
- Food and Nutritional Sciences Programme, School of Life Sciences, Faculty of Science, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong; Biochemistry Programme, School of Life Sciences, Faculty of Science, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong.
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15
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Wang Y, Tan W, Wang CC, Leung LK. Exposure to aflatoxin B1 in late gestation alters protein kinase C and apoptotic protein expression in murine placenta. Reprod Toxicol 2016; 61:68-74. [PMID: 26968497 DOI: 10.1016/j.reprotox.2016.03.001] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2015] [Revised: 02/25/2016] [Accepted: 03/04/2016] [Indexed: 02/07/2023]
Abstract
Mycotoxins are chemicals with diverse toxicities that are produced by fungi. Aflatoxin B1 is commonly found in plant food, and is generally regarded as one of the most toxic mycotoxins. In the present study, pregnant ICR mice were given p.o. daily doses of aflatoxin B1 at 0, 0.05, 0.5, 5mg/kg for 4days (from E13.5 to E16.5). Compared to the control group, time of delivery was shortened and low birth weight was induced in mice treated with 0.5 and 5mg aflatoxin B1/kg, respectively. Placental tissue isolated from pregnant mice at E17.5 showed that the mRNA expression of crh was increased in aflatoxin-treated groups. This upregulation might signify premature delivery. Further analysis indicated that Pkc proteins were activated and Bcl-2 was reduced in the placental tissue of the aflatoxin-treated groups. Reduction of the anti-apoptotic proteins, on the other hand, might affect the morphorgenesis and maintenance of the placenta.
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Affiliation(s)
- Yanfei Wang
- Shandong Provincial Key Laboratory of Animal Cells and Developmental Biology, Institute of Developmental Biology, School of Life Sciences, Shandong University, Jinan, Shandong, People's Republic of China; Biochemistry Programme, School of Life Sciences, Faculty of Science, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong
| | - Wenjuan Tan
- Biochemistry Programme, School of Life Sciences, Faculty of Science, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong
| | - C C Wang
- Department of Obstetrics and Gynecology, Faculty of Medicine, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong
| | - Lai K Leung
- Biochemistry Programme, School of Life Sciences, Faculty of Science, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong; Food and Nutritional Sciences Programme, School of Life Sciences, Faculty of Science, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong.
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16
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Wong TY, Lin SM, Leung LK. The Flavone Luteolin Suppresses SREBP-2 Expression and Post-Translational Activation in Hepatic Cells. PLoS One 2015; 10:e0135637. [PMID: 26302339 PMCID: PMC4547722 DOI: 10.1371/journal.pone.0135637] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2015] [Accepted: 07/24/2015] [Indexed: 11/18/2022] Open
Abstract
High blood cholesterol has been associated with cardiovascular diseases. The enzyme HMG CoA reductase (HMGCR) is responsible for cholesterol synthesis, and inhibitors of this enzyme (statins) have been used clinically to control blood cholesterol. Sterol regulatory element binding protein (SREBP) -2 is a key transcription factor in cholesterol metabolism, and HMGCR is a target gene of SREBP-2. Attenuating SREBP-2 activity could potentially minimize the expression of HMGCR. Luteolin is a flavone that is commonly detected in plant foods. In the present study, Luteolin suppressed the expression of SREBP-2 at concentrations as low as 1 μM in the hepatic cell lines WRL and HepG2. This flavone also prevented the nuclear translocation of SREBP-2. Post-translational processing of SREBP-2 protein was required for nuclear translocation. Luteolin partially blocked this activation route through increased AMP kinase (AMPK) activation. At the transcriptional level, the mRNA and protein expression of SREBP-2 were reduced through luteolin. A reporter gene assay also verified that the transcription of SREBF2 was weakened in response to this flavone. The reduced expression and protein processing of SREBP-2 resulted in decreased nuclear translocation. Thus, the transcription of HMGCR was also decreased after luteolin treatment. In summary, the results of the present study showed that luteolin modulates HMGCR transcription by decreasing the expression and nuclear translocation of SREBP-2.
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Affiliation(s)
- Tsz Yan Wong
- Food and Nutritional Sciences Programme, School of Life Sciences, Faculty of Science, The Chinese University of Hong Kong, Shatin, Hong Kong S.A.R., People's Republic of China
| | - Shu-mei Lin
- Dept. of Food Science, National Chiayi University, Chiayi City, Taiwan, (R.O.C.)
| | - Lai K. Leung
- Food and Nutritional Sciences Programme, School of Life Sciences, Faculty of Science, The Chinese University of Hong Kong, Shatin, Hong Kong S.A.R., People's Republic of China
- Biochemistry Programme, School of Life Sciences, Faculty of Science, The Chinese University of Hong Kong, Shatin, Hong Kong S.A.R., People's Republic of China
- * E-mail:
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Wong TY, Lin SM, Poon CH, Leung LK. The licorice flavonoid isoliquiritigenin reduces DNA-binding activity of AhR in MCF-7 cells. Chem Biol Interact 2014; 221:70-6. [DOI: 10.1016/j.cbi.2014.07.015] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2014] [Revised: 05/27/2014] [Accepted: 07/29/2014] [Indexed: 12/02/2022]
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Li F, Wong TY, Lin SM, Chow S, Cheung WH, Chan FL, Chen S, Leung LK. Coadministrating luteolin minimizes the side effects of the aromatase inhibitor letrozole. J Pharmacol Exp Ther 2014; 351:270-7. [PMID: 25138022 DOI: 10.1124/jpet.114.216754] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Aromatase inhibitors (AIs) have been used as adjuvant therapeutic agents for breast cancer. Their adverse side effect on blood lipid is well documented. Some natural compounds have been shown to be potential AIs. In the present study, we compared the efficacy of the flavonoid luteolin to the clinically approved AI letrozole (Femara; Novartis Pharmaceuticals, East Hanover, NJ) in a cell and a mouse model. In the in vitro experimental results for aromatase inhibition, the Ki values of luteolin and letrozole were estimated to be 2.44 µM and 0.41 nM, respectively. Both letrozole and luteolin appeared to be competitive inhibitors. Subsequently, an animal model was used for the comparison. Aromatase-expressing MCF-7 cells were transplanted into ovariectomized athymic mice. Luteolin was given by mouth at 5, 20, and 50 mg/kg, whereas letrozole was administered by intravenous injection. Similar to letrozole, luteolin administration reduced plasma estrogen concentrations and suppressed the xenograft proliferation. The regulation of cell cycle and apoptotic proteins-such as a decrease in the expression of Bcl-xL, cyclin-A/D1/E, CDK2/4, and increase in that of Bax-was about the same in both treatments. The most significant disparity was on blood lipids. In contrast to letrozole, luteolin increased fasting plasma high-density lipoprotein concentrations and produced a desirable blood lipid profile. These results suggested that the flavonoid could be a coadjuvant therapeutic agent without impairing the action of AIs.
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Affiliation(s)
- Fengjuan Li
- Department of Physiology and Pathophysiology, Peking University Health Science Center, Beijing, China (F.L.); Biochemistry Programme, School of Life Sciences, Faculty of Science (F.L), Food and Nutritional Sciences Programme , School of Life Sciences, Faculty of Science (T.Y.W., L.K.L.), Department of Orthopaedics and Traumatology, Faculty of Medicine (Si.C., W.C.), and School of Biomedical Sciences, Faculty of Medicine (F.L.C.), The Chinese University of Hong Kong, Shatin, Hong Kong; Department of Food Science, National Chiayi University, Chiayi City, Taiwan, Republic of China (S.L.); and Department of Cancer Biology, Beckman Research Institute of the City of Hope, Duarte, California (Sh.C.)
| | - Tsz Yan Wong
- Department of Physiology and Pathophysiology, Peking University Health Science Center, Beijing, China (F.L.); Biochemistry Programme, School of Life Sciences, Faculty of Science (F.L), Food and Nutritional Sciences Programme , School of Life Sciences, Faculty of Science (T.Y.W., L.K.L.), Department of Orthopaedics and Traumatology, Faculty of Medicine (Si.C., W.C.), and School of Biomedical Sciences, Faculty of Medicine (F.L.C.), The Chinese University of Hong Kong, Shatin, Hong Kong; Department of Food Science, National Chiayi University, Chiayi City, Taiwan, Republic of China (S.L.); and Department of Cancer Biology, Beckman Research Institute of the City of Hope, Duarte, California (Sh.C.)
| | - Shu-mei Lin
- Department of Physiology and Pathophysiology, Peking University Health Science Center, Beijing, China (F.L.); Biochemistry Programme, School of Life Sciences, Faculty of Science (F.L), Food and Nutritional Sciences Programme , School of Life Sciences, Faculty of Science (T.Y.W., L.K.L.), Department of Orthopaedics and Traumatology, Faculty of Medicine (Si.C., W.C.), and School of Biomedical Sciences, Faculty of Medicine (F.L.C.), The Chinese University of Hong Kong, Shatin, Hong Kong; Department of Food Science, National Chiayi University, Chiayi City, Taiwan, Republic of China (S.L.); and Department of Cancer Biology, Beckman Research Institute of the City of Hope, Duarte, California (Sh.C.)
| | - Simon Chow
- Department of Physiology and Pathophysiology, Peking University Health Science Center, Beijing, China (F.L.); Biochemistry Programme, School of Life Sciences, Faculty of Science (F.L), Food and Nutritional Sciences Programme , School of Life Sciences, Faculty of Science (T.Y.W., L.K.L.), Department of Orthopaedics and Traumatology, Faculty of Medicine (Si.C., W.C.), and School of Biomedical Sciences, Faculty of Medicine (F.L.C.), The Chinese University of Hong Kong, Shatin, Hong Kong; Department of Food Science, National Chiayi University, Chiayi City, Taiwan, Republic of China (S.L.); and Department of Cancer Biology, Beckman Research Institute of the City of Hope, Duarte, California (Sh.C.)
| | - Wing-hoi Cheung
- Department of Physiology and Pathophysiology, Peking University Health Science Center, Beijing, China (F.L.); Biochemistry Programme, School of Life Sciences, Faculty of Science (F.L), Food and Nutritional Sciences Programme , School of Life Sciences, Faculty of Science (T.Y.W., L.K.L.), Department of Orthopaedics and Traumatology, Faculty of Medicine (Si.C., W.C.), and School of Biomedical Sciences, Faculty of Medicine (F.L.C.), The Chinese University of Hong Kong, Shatin, Hong Kong; Department of Food Science, National Chiayi University, Chiayi City, Taiwan, Republic of China (S.L.); and Department of Cancer Biology, Beckman Research Institute of the City of Hope, Duarte, California (Sh.C.)
| | - Franky L Chan
- Department of Physiology and Pathophysiology, Peking University Health Science Center, Beijing, China (F.L.); Biochemistry Programme, School of Life Sciences, Faculty of Science (F.L), Food and Nutritional Sciences Programme , School of Life Sciences, Faculty of Science (T.Y.W., L.K.L.), Department of Orthopaedics and Traumatology, Faculty of Medicine (Si.C., W.C.), and School of Biomedical Sciences, Faculty of Medicine (F.L.C.), The Chinese University of Hong Kong, Shatin, Hong Kong; Department of Food Science, National Chiayi University, Chiayi City, Taiwan, Republic of China (S.L.); and Department of Cancer Biology, Beckman Research Institute of the City of Hope, Duarte, California (Sh.C.)
| | - Shiuan Chen
- Department of Physiology and Pathophysiology, Peking University Health Science Center, Beijing, China (F.L.); Biochemistry Programme, School of Life Sciences, Faculty of Science (F.L), Food and Nutritional Sciences Programme , School of Life Sciences, Faculty of Science (T.Y.W., L.K.L.), Department of Orthopaedics and Traumatology, Faculty of Medicine (Si.C., W.C.), and School of Biomedical Sciences, Faculty of Medicine (F.L.C.), The Chinese University of Hong Kong, Shatin, Hong Kong; Department of Food Science, National Chiayi University, Chiayi City, Taiwan, Republic of China (S.L.); and Department of Cancer Biology, Beckman Research Institute of the City of Hope, Duarte, California (Sh.C.)
| | - Lai K Leung
- Department of Physiology and Pathophysiology, Peking University Health Science Center, Beijing, China (F.L.); Biochemistry Programme, School of Life Sciences, Faculty of Science (F.L), Food and Nutritional Sciences Programme , School of Life Sciences, Faculty of Science (T.Y.W., L.K.L.), Department of Orthopaedics and Traumatology, Faculty of Medicine (Si.C., W.C.), and School of Biomedical Sciences, Faculty of Medicine (F.L.C.), The Chinese University of Hong Kong, Shatin, Hong Kong; Department of Food Science, National Chiayi University, Chiayi City, Taiwan, Republic of China (S.L.); and Department of Cancer Biology, Beckman Research Institute of the City of Hope, Duarte, California (Sh.C.)
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Xiao Z, Huang C, Wu J, Sun L, Hao W, Leung LK, Huang J. The neuroprotective effects of ipriflavone against H2O2 and amyloid beta induced toxicity in human neuroblastoma SH-SY5Y cells. Eur J Pharmacol 2013; 721:286-93. [DOI: 10.1016/j.ejphar.2013.09.023] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2013] [Revised: 08/25/2013] [Accepted: 09/06/2013] [Indexed: 01/15/2023]
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20
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Wang Y, Li L, Wang CC, Leung LK. Effect of zeranol on expression of apoptotic and cell cycle proteins in murine placentae. Toxicology 2013; 314:148-54. [PMID: 24120472 DOI: 10.1016/j.tox.2013.09.011] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2013] [Revised: 09/04/2013] [Accepted: 09/20/2013] [Indexed: 11/26/2022]
Abstract
Mycotoxins are chemicals produced by fungus and many of them are toxic to humans. Zeranol is a mycotoxin used to promote growth in cattle in North America; yet such a practice draws concern about the residual compound in meat in European countries. In the present study, the toxicity of zeranol was tested in a mouse model for reproduction. Pregnant ICR mice were given p.o. daily doses of zeranol at 0, 1, 10, 100mg/kg for 4 days (from E13.5 to E16.5). Increased rates of fetal resorption at late gestation (E17.5) and preterm birth (<E18.5) were observed in mice treated with zeranol. The apparent factors causing these perinatal conditions were subsequently investigated. Perturbation of cell death or proliferation-related proteins might deter the growth and maintenance of the placentae, and the subsequent fetal resorption and preterm birth. Placental tissue isolated from pregnant mice at E17.5 showed that the expressions of Cdk2 and 4, Cyclin D1 and Bcl-xL were reduced in zeranol-treatment groups. The downregulations might signify growth or maintenance failure in the placentae. Furthermore, reduction in the signaling proteins Erk-1/2 in the placentae could trigger the decrease in the cell cycle/apoptosis proteins. In addition, relaxin is associated with preterm labor. An increase in placental Relaxin-1 expression could also contribute to early delivery in this study. Result of the current study suggested that exposure to zeranol might introduce adverse effect in pregnancy.
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Affiliation(s)
- Yanfei Wang
- Shandong Provincial Key Laboratory of Animal Cells and Developmental Biology, Institute of Developmental Biology, School of Life Sciences, Shandong University, Jinan, Shandong, People's Republic of China; Biochemistry Programme, School of Life Sciences, Faculty of Science, The Chinese University of Hong Kong, Shatin, NT, Hong Kong
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Tan W, Wong TY, Wang Y, Huang J, Leung LK. CYP19 expression is induced by 2,3,7,8-tetrachloro-dibenzo-para-dioxin in human glioma cells. Mol Cell Endocrinol 2013; 375:106-12. [PMID: 23727336 DOI: 10.1016/j.mce.2013.05.018] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/11/2013] [Revised: 04/24/2013] [Accepted: 05/21/2013] [Indexed: 11/24/2022]
Abstract
Dioxins are the most concerned environmental pollutants. Recent studies have shown that these compounds could disrupt the proper functioning of our endocrine system. Estrogen is synthesized in glial cells of the brain. The hormone has been linked to the maintenance of normal brain operation, ranging from neurotransmission to synapse formation. Aromatase or CYP19 is the enzyme responsible for estrogen synthesis. In the present study, we demonstrated that 2,3,7,8-tetrachloro-dibenzo-para-dioxin (TCDD) stimulated the enzyme activity in human brain cells as low as 1pM. Increased brain-specific CYP19 mRNA species was also observed in these cells. Since the brain-specific promoter I.f of CYP19 contains two binding motifs for CCAAT/enhancer binding protein, electrophoretic mobility shift assay was performed to validate the activation. We further traced the triggering signal and found that the mitogen-activated protein kinases ERK-1/2 were activated. In summary, TCDD could induce CYP19 transcription in brain cells. Exposure to the pollutant might perturb the hormonal balance in the brain.
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Affiliation(s)
- Wenjuan Tan
- Biochemistry Programme, School of Life Sciences, Faculty of Science, The Chinese University of Hong Kong, Shatin, NT, Hong Kong
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Li F, Chow S, Cheung WH, Chan FL, Chen S, Leung LK. The citrus flavonone hesperetin prevents letrozole-induced bone loss in a mouse model of breast cancer. J Nutr Biochem 2013; 24:1112-6. [DOI: 10.1016/j.jnutbio.2012.08.010] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2012] [Revised: 08/03/2012] [Accepted: 08/13/2012] [Indexed: 11/16/2022]
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Tan W, Huang H, Wang Y, Wong TY, Wang C, Leung LK. Bisphenol A differentially activates protein kinase C isoforms in murine placental tissue. Toxicol Appl Pharmacol 2013; 269:163-8. [DOI: 10.1016/j.taap.2013.03.016] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2012] [Revised: 03/20/2013] [Accepted: 03/21/2013] [Indexed: 01/21/2023]
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Wang Y, Tan W, Leung LK. Zeranol upregulates corticotropin releasing hormone expression in the placental cell line JEG-3. Toxicol Lett 2013; 219:218-22. [PMID: 23538034 DOI: 10.1016/j.toxlet.2013.03.016] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2013] [Revised: 03/12/2013] [Accepted: 03/17/2013] [Indexed: 11/16/2022]
Abstract
Corticotrophin-releasing hormone (CRH) plays a pivotal role in the control of parturition in human. Increased amount of plasma CRH is associated with pre-mature delivery. Zeranol or α-zearalanol is a mycotoxin produced by fungi in the Fusarium family. Unlike other mycotoxins, exposure to zeranol appears to have minimal health risk. In North America, it is used as a growth-promoting agent in livestock. Because of the health concern of zeranol residue in meat, this practice has not been adopted in Europe. In our study zeranol could induce CRH protein expression in JEG-3 cells as low as 0.1nM. As electrophoretic mobility shift assay indicated an increase in the CRE binding activity in CRH promoter, the induction was likely triggered by transcriptional regulation. We further looked into the signal transduction pathway and PKCδ and ERK-1/2 were found to be activated. This study showed that zeranol could increase CRH expression in placental cells, and the findings might be a concern for pregnant women.
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Affiliation(s)
- Yanfei Wang
- Biochemistry Programme, School of Life Sciences, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong
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LI F, Ye L, Chan FL, Chen S, Leung LK. The citrus flavonone hesperetin inhibits growth of aromatase‐expressing MCF‐7 tumor and reduces the effective dose in letrozole‐treated mice. FASEB J 2012. [DOI: 10.1096/fasebj.26.1_supplement.1023.16] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Fengjuan LI
- The Chinese University of Hong KongHong KongHong Kong
| | - Lan Ye
- The Chinese University of Hong KongHong KongHong Kong
| | | | - Shiuan Chen
- Beckman Research Institute of the City of HopeDuarteCA
| | - Lai K. Leung
- The Chinese University of Hong KongHong KongHong Kong
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Ye L, Chan FL, Chen S, Leung LK. The citrus flavonone hesperetin inhibits growth of aromatase-expressing MCF-7 tumor in ovariectomized athymic mice. J Nutr Biochem 2011; 23:1230-7. [PMID: 22209285 DOI: 10.1016/j.jnutbio.2011.07.003] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2011] [Revised: 06/02/2011] [Accepted: 07/12/2011] [Indexed: 11/16/2022]
Abstract
Aromatase is responsible for the rate-determining reaction in estrogen synthesis and is a prime target for treating estrogen-receptor-positive breast cancer. Previous in vitro study has demonstrated that apigenin (APG), naringenin (NGN) and hesperetin (HSP) are three of the most potent natural aromatase inhibitors. Because the enzyme inhibition could potentially block breast cancer development, we employed an established postmenopausal breast cancer model to examine the chemopreventive effect of these flavonoids in vivo. Athymic mice were ovariectomized and transplanted with aromatase-overexpressing MCF-7 cells. Dietary administration of HSP at 1000 ppm and 5000 ppm significantly deterred the xenograft growth, while a null effect was observed in mice treated with APG or NGN. Further study illustrated that plasma estrogen in HSP-treated mice was reduced. Messenger RNA expression of the estrogen-responsive gene pS2 was also decreased in the tumors of mice treated with 1000 and 5000 ppm HSP. On the other hand, western analysis indicated that cyclin D1, CDK4 and Bcl-x(L) were reduced in the tumors. This study suggested that HSP could be a potential chemopreventive agent against breast carcinogenesis through aromatase inhibition.
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Affiliation(s)
- Lan Ye
- Biochemistry Programme, School of Life Sciences, Faculty of Science, the Chinese University of Hong Kong
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27
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Li F, Ye L, Lin SM, Leung LK. Dietary flavones and flavonones display differential effects on aromatase (CYP19) transcription in the breast cancer cells MCF-7. Mol Cell Endocrinol 2011; 344:51-8. [PMID: 21741436 DOI: 10.1016/j.mce.2011.06.024] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/29/2011] [Revised: 06/09/2011] [Accepted: 06/24/2011] [Indexed: 11/19/2022]
Abstract
Aromatase or cytochrome P450 (CYP19) enzyme catalyzes the rate-determining reaction in estrogen synthesis. Inhibiting aromatase is a major strategy in treating breast cancer patients. However, suppression on the transcriptional activity may be equally important in controlling aromatase. Dietary flavones and flavonones have been previously demonstrated to be the most potent aromatase-inhibitory flavonoids. In the present study we examined their effects on the transcription regulation of CYP19 in MCF-7 cells. Real-time PCR results indicated that luteolin suppressed CYP19 mRNA expression while hesperetin increased it. Reporter gene assays were employed to look into the transactivity of CYP19 driven by promoters I.3 and II, and the result was consistent with the observation in mRNA expression. Further investigation using truncation reporter gene and electrophoretic mobility shift assays suggested that luteolin and hesperetin differentially influenced AP-1- and C/EBP-binding on the CYP19 promoter. Western blot analysis indicated that signaling transduction pathways involving JNK and ERK could be the underlying mechanisms for their actions. The present study showed that dietary flavones and flavonones might differentially regulate aromatase transcription in breast cells in addition to the inhibition at the enzyme level.
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Affiliation(s)
- Fengjuan Li
- Biochemistry Programme, School of Life Sciences, Faculty of Science, The Chinese University of Hong Kong, Shatin, NT, Hong Kong
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28
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Yi Lau GT, Leung LK. The dietary flavonoid apigenin blocks phorbol 12-myristate 13-acetate-induced COX-2 transcriptional activity in breast cell lines. Food Chem Toxicol 2010; 48:3022-7. [DOI: 10.1016/j.fct.2010.07.046] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2010] [Revised: 07/12/2010] [Accepted: 07/29/2010] [Indexed: 11/29/2022]
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Lau GT, Ye L, Leung LK. The licorice flavonoid isoliquiritigenin suppresses phorbol ester-induced cyclooxygenase-2 expression in the non-tumorigenic MCF-10A breast cell line. Planta Med 2010; 76:780-785. [PMID: 20033868 DOI: 10.1055/s-0029-1240699] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Cyclooxygenase (COX) is the rate-limiting enzyme for the conversion of prostaglandins from arachidonic acid. Upregulation of COX-2 has been well documented during tumorigenesis and metastasis of breast cancer. Isoliquiritigenin (ILN), a flavonoid isolated from licorice (the rhizomes of GLYCYRRHIZA GLABRA, a member of the bean plant family), is known to be a potential suppressor of COX-2 expression. This study focuses on phorbol ester-induced COX-2 expression in the non-tumorigenic MCF-10A cells. Real-time PCR and Western blotting indicated that ILN at 5 microM or above significantly inhibited phorbol 12-myristate 13-acetate (PMA)-induced COX-2 expression in the breast cells. The activated PKC alpha appeared to be not affected, whereas its downstream mitogen-activated protein kinase (MAPK) ERK-1/2 was deactivated. ERK can activate the transcriptional factor binding of AP-1 or CRE, which can be located at the COX-2 promoter region (- 72/- 53). Electrophoretic mobility shift assays illustrated that ILN suppressed DNA binding at this region. The shifted bands could be competed off with consensus sequences of AP-1 and CRE, and the supershift assay demonstrated that CREB-1 instead of c-Jun was responsible for the binding. This study showed that ILN downregulated PMA-induced COX-2 expression by modulating ERK-1/2 signaling, a finding that may be relevant to the disease prevention properties of licorice.
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Affiliation(s)
- Grace Tak Lau
- Food and Nutritional Sciences Programme, The Chinese University of Hong Kong, Shatin, N. T., Hong Kong
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Wang H, Leung LK. The carotenoid lycopene differentially regulates phase I and II enzymes in dimethylbenz[a]anthracene-induced MCF-7 cells. Nutrition 2010; 26:1181-7. [PMID: 20400267 DOI: 10.1016/j.nut.2009.11.013] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2009] [Revised: 08/17/2009] [Accepted: 11/12/2009] [Indexed: 10/19/2022]
Abstract
OBJECTIVE Lycopene is a carotenoid widely distributed in fruit and vegetables. Epidemiological studies suggest that lycopene consumption is associated with decreased cancer risk. Animal studies have revealed that lycopene may protect against dimethylbenz[a]anthracene (DMBA)-induced carcinogenesis in the breast. Polycylic aromatic hydrocarbons (PAH) are environmental toxicants that can be metabolized by two phase I enzymes, cytochrome P450 1A1 and 1B1. Products formed by these reactions are DNA-attacking moieties. Mutation generated by these genotoxic intermediates is believed to be an important step in cancer initiation. Some phase II detoxifying enzymes, such as uridine diphosphate (UDP)-glucuronosyltransferases (UGT), facilitate the elimination of these genotoxic moieties. In the present study, the mechanism by which lycopene prevented PAH-induced carcinogenesis in the breast was investigated in a cell culture model MCF-7. RESEARCH METHODS AND PROCEDURES The inhibitory action of lycopene on CYP1 enzymes was assessed in recombinant protein and cell culture using ethoxyresorufin-O-deethylase assay. Messenger RNA expressions of CYP1A1 and 1B1, and UGT were estimated by semi-quantitative reverse transcription-polymerase chain reaction. Cells were co-treated with tritiated DMBA and lycopene for quantifying the protection of the phytocompound against DNA lesion generated from the DMBA metabolites. RESULTS Lycopene inhibited recombinant CYP1A1 and CYP1B1 with estimated K(i)s in the micromolar range. In MCF-7 cells, lycopene administration slightly reduced the DMBA-induced ethoxyresorufin-O-deethylase activity by 20%. Meanwhile, a four-fold increase in microsomal UGT activity was observed. CONCLUSION The present study illustrated that phase I enzyme inhibition and phase II enzyme induction were the underlying chemoprotective mechanisms of lycopene against PAH-induced toxicity.
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Affiliation(s)
- Huan Wang
- Department of Biochemistry, The Chinese University of Hong Kong, Shatin, NT, Hong Kong
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31
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Chan MY, Huang H, Leung LK. 2,3,7,8-Tetrachlorodibenzo-para-dioxin increases aromatase (CYP19) mRNA stability in MCF-7 cells. Mol Cell Endocrinol 2010; 317:8-13. [PMID: 19962423 DOI: 10.1016/j.mce.2009.11.012] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/06/2009] [Revised: 09/26/2009] [Accepted: 11/10/2009] [Indexed: 10/20/2022]
Abstract
Dioxins are industrial pollutants that can be bio-accumulative in our food chain. Humans can be exposed to this class of pollutant through contaminated food, air, drinking water, etc. Displaying both pro- and anti-estrogenic properties, these pollutants are also known as endocrine disruptors. The link between breast cancer and TCDD exposure has not been resolved, although TCDD is classified as 'known human carcinogen'. Estrogen is a documented risk factor for breast carcinogenesis. In the present study, effect of 2,3,7,8-tetrachlorodibenzo-para-dioxin (TCDD) on estrogen synthesis was investigated in the breast cancer cells MCF-7. Our results showed that TCDD increased the aromatase activity in a time- and dose-dependent manner. Real-time PCR and western blot analysis verified the induced expression by 2-3-fold; however, gene reporter assay revealed that the promoter activity of exons I.3 and II was not elevated. Further investigation indicated that TCDD slowed down the CYP19 mRNA degradation with concurrent activation of ERK. The ERK inhibitor U0126 could reverse the extended stability of the transcripts. In summary this study demonstrated that TCDD might induce a post-transcriptional regulatory mechanism of gene expression in breast cancer cells.
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Affiliation(s)
- Ming Yan Chan
- Department of Biochemistry, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong
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Ye L, Chan MY, Leung LK. The soy isoflavone genistein induces estrogen synthesis in an extragonadal pathway. Mol Cell Endocrinol 2009; 302:73-80. [PMID: 19356625 DOI: 10.1016/j.mce.2009.01.003] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/20/2008] [Revised: 01/07/2009] [Accepted: 01/08/2009] [Indexed: 01/22/2023]
Abstract
Genistein is a phytoestrogen isolated from soyabean, and is a potential nutraceutical gearing for women suffering from perimenopausal symptoms. Because of its differential binding affinity to estrogen receptor (ER) isoforms, genistein is described as a selective estrogen receptor modulator (SERM). The ligand-receptor interaction is established, but the potential confounding factors have not been fully addressed. Alteration in estrogen metabolism is an important issue when determining the downstream effect of ER. Aromatase or CYP19 catalyzes the rate-limiting reaction of estrogen synthesis, and is highly expressed in the ovary. This organ is the source of estrogen in females. After menopause the ovaries cease to produce the hormone, and localized estrogen synthesis in extragonadal tissues could become physiologically significant. In the present study, effect of genistein on CYP19 regulation was investigated in the hepatic cells HepG2. The phytoestrogen induced aromatase activity in the cells. Increased mRNA expression with concurrent elevation in the usage of promoters I.3/II was also demonstrated. Luciferase reporter gene assays verified the transcriptional control dictated by the specific promoters under genistein treatment. Several protein kinases were examined, and PKC?, P38, ERK-1/2 appeared to be activated. Subsequent inhibition and expression experiments demonstrated the involvement of these kinases. The transcriptional factor CREB was ultimately activated in the gene regulation. The present study illustrated an extragonadal pathway by which genistein might increase estrogen synthesis.
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Affiliation(s)
- Lan Ye
- Department of Biochemistry, Faculty of Science, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong
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Ye L, Gho WM, Chan FL, Chen S, Leung LK. Dietary administration of the licorice flavonoid isoliquiritigenin deters the growth of MCF-7 cells overexpressing aromatase. Int J Cancer 2009; 124:1028-36. [PMID: 19065667 DOI: 10.1002/ijc.24046] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Licorice is the sweet-tasting rhizomes of a bean plant and is quite commonly used in Western countries for culinary purposes, while it is a medicinal herb in China. Many flavonoids have been isolated from licorice, and their pharmacological properties may be applicable in preventive medicine. Overexposure to estrogen has been implicated in the etiology of breast cancer, and cytochrome P450 (CYP) 19 enzyme, or aromatase, catalyzes the rate-limiting reaction. Phytocompounds that are able to inhibit this enzyme may potentially suppress breast cancer development. In the present study the licorice flavonoid isoliquiritigenin (ILN) was shown to be an aromatase inhibitor in recombinant protein and MCF-7 cells stably transfected with CYP19 (MCF-7aro). ILN displayed a K(i) value of around 3 muM, and it also blocked the MCF-7aro cell growth pertaining to the enzyme activity in vitro. Subsequently, the compound administered in diet was given to ovariectomized athymic mice transplanted with MCF-7aro cells. This mouse model is widely accepted for studying postmenopausal breast cancer. The phytochemical significantly deterred the xenograft growth without affecting the body weight. Subsequently, the flavonoid's effect on CYP19 transcriptional control in vitro was also investigated. At the mRNA level, ILN could also suppress the expression in wild-type MCF-7 cells. Reporter gene assay and real-time PCR verified that the transactivity of CYP19 driven by promoters I.3 and II was suppressed in these cells. Deactivation of C/EBP could be the underlying molecular mechanism. Our study demonstrated that ILN was an inhibitor of aromatase and a potential chemopreventive agent against breast cancer.
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Affiliation(s)
- Lan Ye
- Department of Biochemistry, Chinese University of Hong Kong, NT, Hong Kong
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34
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Ye L, Leung LK. Effect of dioxin exposure on aromatase expression in ovariectomized rats. Toxicol Appl Pharmacol 2008; 229:102-8. [DOI: 10.1016/j.taap.2008.01.003] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2007] [Revised: 01/03/2008] [Accepted: 01/11/2008] [Indexed: 11/15/2022]
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Wang Y, Ye L, Leung LK. A positive feedback pathway of estrogen biosynthesis in breast cancer cells is contained by resveratrol. Toxicology 2008; 248:130-5. [PMID: 18462857 DOI: 10.1016/j.tox.2008.03.017] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2008] [Revised: 03/19/2008] [Accepted: 03/24/2008] [Indexed: 10/22/2022]
Abstract
Cytochrome P450 (CYP) 19 enzyme or aromatase catalyses the rate-determining step of estrogen synthesis. The transcriptional control of CYP19 gene is highly specific in different cell types, for instance, Promoter I.3/II is commonly used for regulation in breast cancer cells. Recently, a positive feedback pathway for estrogen synthesis has been identified in ER alpha expressing SK-BR-3 cells. CYP19 mRNA abundance and activity are increased in this pathway and the promoter usage is switched from Promoter I.3/II to I.1 through a non-genomic process. In the present study, effect of the phytocompound resveratrol on this Promoter I.1-controlled expression of aromatase was investigated. Results indicated that resveratrol reduced the estradiol-induced mRNA abundance in SK-BR-3 cells expressing ER alpha. Luciferase reporter gene assays revealed that resveratrol could also repress the transcriptional control dictated by Promoter I.1. Since the ERE-driven luciferase activity was not repressed by resveratrol, the nuclear events of estrogen were unlikely to be suppressed by resveratrol. Instead the phytochemical reduced the amount of ERK activated by estradiol, which could be the pathway responsible for Promoter I.1 transactivation and the induced CYP19 expression. The present study illustrated that resveratrol impeded the non-genomic induction of estrogen on CYP19.
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Affiliation(s)
- Yun Wang
- Department of Biochemistry, The Chinese University of Hong Kong, Shatin, NT, Hong Kong, China
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Leung LK, Yuen YM, Leung HY, Wang Y. Dietary soya isoflavones and breast carcinogenesis: a perspective from a cell-culture model. Nutr Res Rev 2007; 18:202-11. [DOI: 10.1079/nrr2005111] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Southeast Asian women have a lower incidence of breast cancer than their counterparts in the West. Epidemiological studies have indicated that soya consumption may be a contributing factor. Carcinogenesis is a process involving multiple stages. The present review attempts to fit the cellular mechanisms attributed to soya isoflavones into these different stages. Many cell-culture studies have reported the growth-inhibitory effect of soya isoflavones; however, with the non-physiological concentrations employed in these studies it would be difficult to explain the protection mechanisms observed in epidemiological studies. Our laboratory has previously found that genistein inhibits cytochrome P450 (CYP)1A1 and CYP1B1. The inhibition implies that soya consumption may have the potential to prevent chemical carcinogenesis. The preferential inhibition of CYP1B1 may also block the oestrogen-initiated carcinogenesis. The antagonism of oestrogen receptor (ER) binding can affect the cell-proliferative phase, which is likely to be important in the promotion stage of breast cancer. Since our laboratory and others have indicated that genistein at physiological concentrations has no effect on the downstream activities of ER binding, the antagonism of ER is not likely to be a contributing factor in the disease prevention. Moreover, soya isoflavones cannot inhibit aromatase (CYP19), which is the enzyme responsible for oestrogen synthesis. In the present review various cellular activities altered by soya isoflavones are discussed
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Leung HY, Wang Y, Leung LK. Differential effect of over-expressing UGT1A1 and CYP1A1 on xenobiotic assault in MCF-7 cells. Toxicology 2007; 242:153-9. [PMID: 17981384 DOI: 10.1016/j.tox.2007.09.027] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2007] [Revised: 09/14/2007] [Accepted: 09/18/2007] [Indexed: 10/22/2022]
Abstract
Gene mutation has been considered as a major step of carcinogenesis. Some defective genes may induce spontaneous tumorigenesis, while others are required to interact with the environment to induce cancer. CYP1A1 and UGT1A1 are encoded for the respective phase I and II drug-metabolizing enzymes. Their expressions have been associated with breast cancer incidence in women, and some xenobiotics are substrates of these two enzymes. In the current study, cytochrome P450 (CYP) 1A1 and UDP-glucuronosyltransferase (UGT) 1A1 were over-expressed in the breast cancer MCF-7 cells, and potential interactions between these enzymes and estrogen or polycyclic aromatic hydrocarbon were evaluated. Compared with control cells (MCF-7(VEC)), reduced cell proliferation was seen in cells expressing UGT1A1 (MCF-7(UGT1A1)) under estradiol treatment. 7,12-Dimethylbenz[a]anthracene (DMBA) is an established breast cancer initiator in animal model. Over-expressing UGT1A1 reduced the binding of DMBA to DNA, and increased MCF-7(UGT1A1) intact cells under DMBA treatment was verified by comet assay. On the other hand, intensified DMBA binding and damages were observed in MCF-7(CYP1A1) cells. This study supported that UGT1A1 but not CYP1A1 expression could protect against xenobiotic assault.
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Affiliation(s)
- Hau Y Leung
- Food and Nutritional Sciences Programme, The Chinese University of Hong Kong, Shatin, NT, Hong Kong, China
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38
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Wang Y, Leung LK. Pharmacological concentration of resveratrol suppresses aromatase in JEG-3 cells. Toxicol Lett 2007; 173:175-80. [PMID: 17766065 DOI: 10.1016/j.toxlet.2007.07.009] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2007] [Revised: 07/26/2007] [Accepted: 07/26/2007] [Indexed: 01/05/2023]
Abstract
Estrogen is crucial in preparing of pregnancy, and its role in the maintenance of pregnancy has yet to be elucidated. During the course of pregnancy, the placenta is responsible for the provision of estrogen. The hormone biosynthesis is catalyzed by cytochrome P450 (CYP) 19 or aromatase. In the present study, we screened several common dietary components and identified the grape polyphenol resveratrol to be a potential inhibitor in the hormone synthesis. In a recombinant protein system resveratrol inhibited the aromatase activity with an IC(50) value of approximately 40 microM. Subsequent analysis was performed in the human placental JEG-3 cells, and 25 microM resveratrol significantly reduced the mRNA abundance in these cells. Since the transcriptional control of CYP19 gene is tissue-specific and the proximal promoter region of exon Ia has previously been shown to be crucial in CYP19 expression in placental cells, we also evaluated the promoter activity of this gene. Reporter gene assays revealed that resveratrol repressed the transcriptional control of promoter Ia. The present study illustrated the possibility that dietary supplementation of resveratrol interfered with the normal functioning of placental cells.
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Affiliation(s)
- Yun Wang
- Department of Biochemistry, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong, China
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Leung HY, Wang Y, Chan HY, Leung LK. Developing a high-throughput system for the screening of cytochrome P450 1A1 – Inhibitory polyphenols. Toxicol In Vitro 2007; 21:996-1002. [PMID: 17560072 DOI: 10.1016/j.tiv.2007.04.005] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2007] [Revised: 03/22/2007] [Accepted: 04/17/2007] [Indexed: 11/20/2022]
Abstract
Polycyclic aromatic hydrocarbons (PAH) are established procarcinogens that can be found in our environment. The carcinogenicity of these compounds is initiated by their metabolic intermediates, and the extent of biotransformation determines the amount of reactive intermediates generated. CYP1A1 is a major enzyme that metabolizes PAH into carcinogenic moieties. Since previous studies have shown that increased CYP1A1 activity is associated with a higher cancer risk. Identifying CYP1A1-inhibitory compounds in diet or natural products are of genuine interest for chemoprevention studies. In this project, a stable cell line expressing human CYP1A1 was established for the screening of potential chemopreventive agents. Because of a lacking cellular transport mechanism in assays performed on recombinant protein, an 'in-cell' assay system might be a better estimate at the tissue level. Theaflavins were strong inhibitors of ethoxyresorufin-O-deethylase (EROD) activity when assayed on recombinant human CYP1A1 protein. However, this inhibition was not observed in the CYP1A1-expressing cells. The 'in-cell' IC50 values determined for compounds such as genistein, quercetin, chalcone, etc. were comparable to the values determined in recombinant protein. This 'in-cell' assay has the additional advantages of short sample processing time, and the tedious procedures of protein expression and purification can be waived.
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Affiliation(s)
- Hau Yi Leung
- Food and Nutritional Sciences Programme, The Chinese University of Hong Kong, Shatin, NT, Hong Kong
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40
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Chan MY, Wai Man G, Chen ZY, Wang J, Leung LK. Oestrogen receptor α is required for biochanin A-induced apolipoprotein A-1 mRNA expression in HepG2 cells. Br J Nutr 2007; 98:534-9. [PMID: 17532863 DOI: 10.1017/s0007114507750857] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Epidemiological studies have indicated that soya consumption may produce a better plasma lipid profile. The effect may be attributed to the phyto-oestrogens in soya. The red clover (Trifolium pratense) isoflavone biochanin A has a chemical structure similar to those phyto-oestrogens found in soya beans, and is marketed as a nutraceutical for alleviating postmenopausal symptoms. In the present study we investigated the effect of biochanin A on the mRNA expression of ApoA-1 in the hepatic cell line HepG2. Real-time PCR revealed that biochanin A increased ApoA-1 mRNA abundance in cells expressing oestrogen receptor (ER) α. Without ERα transfection, biochanin A had no effect on mRNA abundance. In order to study the transcriptional control, a fragment of the 5′-flanking region of theApoA-1gene was amplified and inserted in a firefly luciferase reporter plasmid. The reporter assay indicated that the transactivation of theApoA-1promoter was induced by biochanin A in HepG2 cells transfected with the ERα expression plasmid. This induction was reduced by the anti-oestrogen ICI 182,780, whereas the inhibitors of protein kinase (PK) C, PKA, or mitogen-activated kinase (ERK) had no suppressive effect. The present study illustrated that biochanin A might up regulate hepatic apoA-1 mRNA expression through an ER-dependent pathway.
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Affiliation(s)
- Ming Yan Chan
- Department of Biochemistry, Faculty of Medicine, The Chinese University of Hong Kong, Room 507C, MMW Bldg, Shatin NT, Hong Kong
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Abstract
Biochanin A is an isoflavone isolated from red clover (Trifolium pratense), and is a commercially available nutraceutical for women suffering from postmenopausal symptoms. Isoflavones resemble the structure of oestrogen, and display agonistic and antagonistic interactions with the oestrogen receptor. Overexposure of oestrogen is a major contributing factor in the development of breast cancer, and cytochrome P450 (CYP) 19 enzyme, or aromatase, catalyses the reaction converting androgen to oestrogen. In the present study the effect of biochanin A on the gene regulation and enzyme activity of aromatase was investigated. By assaying MCF-7 cells stably transfected with CYP19, biochanin A inhibited aromatase activity and hampered cell growth attributing to the enzyme activity. In addition, 25 microm-biochanin A significantly reduced CYP19 mRNA abundance in the oestrogen receptor-negative breast cancer cells SK-BR-3. The transcriptional control of the CYP19 gene is exon-specific, and promoter regions I.3 and II have been shown to be responsible for CYP19 expression in SK-BR-3 cells. Luciferase reporter gene assays also revealed that biochanin A could repress the transcriptional control dictated by the promoter regulation. Interestingly, genistein did not inhibit aromatase but it might down regulate promoter I.3 and II transactivation. Since genistein is a major metabolite of biochanin A, it might contribute to biochanin A's suppressive effect on CYP19 expression. The present study illustrated that biochanin A inhibited CYP19 activity and gene expression.
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Affiliation(s)
- Yun Wang
- Department of Biochemistry, The Chinese University of Hong Kong, Shatin NT, Hong Kong
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Abstract
Consumption of fruits and vegetables has been associated with cancer prevention; flavonoids are widely distributed in plant foods and considered to be the active ingredients. Quercetin and kaempferol are two of the most commonly found dietary flavonols, and have been reported to prevent cancer. We have previously reported that the isoflavone genistein and the flavone baicalein exert differential actions on the oestrogen receptor (OR) α in HepG2 cells. Because of the structural resemblance to both isoflavone and flavone, we examined the effects of these dietary flavonols on ORα– and ORβ–specific transactivations and their subsequent involvement in inducing MCF-7 cell death. In the present study, both quercetin and kaempferol were able to compete for OR binding in a cell-free system and were agonistic to ORα and -β expressed in HepG2 cells, while some additive effect was observed in the oestrogen response element (ORE)-driven transcription when 17β-oestradiol was co-administered. Since the bcl-2 promoter contained two ORE, and ORE-driven transcriptional activity and Bcl-2 mRNA expression were increased by treatment with 10 μm-quercetin or kaempferol, it is possible that quercetin and kaempferol might up-regulate Bcl-2 expression through OR transactivation in MCF-7 cells. Cell death ELISA assay performed on MCF-7 cells indicated that an increase of apoptosis occurred at 25 μm-, but not 10 μm-, quercetin or kaempferol. Indirectly the results suggest that OR activation is not sufficient to induce apoptosis and that apoptosis is induced despite an increase in Bcl-2 expression.
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Affiliation(s)
- Lai K Leung
- Department of Biochemistry, The Chinese University of Hong Kong, Shatin, N T, Hong Kong.
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Abstract
Epidemiological studies indicate that Asian women have a lower incidence of breast cancer compared with their counterparts in the West, and soya consumption has been suggested as a contributory factor. Clinical and animal studies have revealed that cyclooxygenase-2 (COX-2) expression is associated with a risk of breast cancer. In the present study, we investigated the effect of soya isoflavones on the expression of COX-2 in the breast cell line MCF-7. Genistein, daidzein and equol were found to inhibit COX-2 expression induced by phorbol 12-myristate 13-acetate (PMA). Similar findings were observed in the COX-2 protein analysis. In order to study transcriptional control, a fragment of the 5'-flanking region of the hCOX-2 gene was amplified and inserted into a firefly luciferase reporter plasmid. The reporter assay indicated that the transactivation of the hCOX-2 promoter was induced by PMA, and activity was inhibited with the co-administration of genistein, daidzein or equol. An activator protein-1 (AP-1)/cyclic AMP response element binding protein (CREB) binding site (-59/-53) was identified in hCOX-2 promoter, and this could be critical in PMA-induced COX-2 expression. Truncation reporter plasmids with (-70/-36) and without (-51/-36) AP-1/CREB were constructed for subsequent analysis. The results revealed that the hCOX-2 promoter transactivation suppressed by isoflavone could be dependent on AP-1/CREB binding. Nonetheless, this study illustrated that the soya isoflavones reduced COX-2 expression, which could be important in the post-initiation events of breast carcinogenesis.
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Affiliation(s)
- Tak Yi Lau
- Food and Nutritional Sciences Programme, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong
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Chan NLS, Wang H, Wang Y, Leung HY, Leung LK. Polycyclic aromatic hydrocarbon-induced CYP1B1 activity is suppressed by perillyl alcohol in MCF-7 cells. Toxicol Appl Pharmacol 2006; 213:98-104. [PMID: 16307765 DOI: 10.1016/j.taap.2005.10.002] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2005] [Revised: 09/28/2005] [Accepted: 10/07/2005] [Indexed: 10/25/2022]
Abstract
Perillyl alcohol (POH) is a dietary monoterpene with potential applications in chemoprevention and chemotherapy. Although clinical trials are under way, POH's physiological and pharmacological properties are still unclear. In the present study, the effect of POH on polycyclic aromatic hydrocarbon (PAH)-induced genotoxicity, and the related expression were examined in MCF-7 cells. Exposure to environmental toxicant increases the risk of cancer. Many of these compounds are pro-carcinogens and are biotransformed into their ultimate genotoxic structures by xenobiotic metabolizing enzymes. CYP1A1 and 1B1 are enzymes that catalyze the biotransformation of dimethylbenz[a]anthracene (DMBA). Our data revealed that 0.5 microM of POH was effective in blocking DMBA-DNA binding. Ethoxyresorufin-O-deethylase (EROD) assay indicated that the administration of POH inhibited the DMBA-induced enzyme activity in MCF-7 cells. Enzyme kinetic analysis revealed that POH inhibited CYP1B1 but not CYP1A1 activity. Quantitative reverse transcriptase-polymerase chain reaction (RT-PCR) assay also demonstrated that the monoterpene reduced CYP1B1 mRNA abundance induced by DMBA. The present study illustrated that POH might inhibit and downregulate CYP1B1, which could protect against PAH-induced carcinogenesis.
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Affiliation(s)
- Nelson L S Chan
- Department of Biochemistry, The Chinese University of Hong Kong, Rm. 507C MMW Bldg., Shatin, N.T., Hong Kong
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Wang Y, Lee KW, Chan FL, Chen S, Leung LK. The red wine polyphenol resveratrol displays bilevel inhibition on aromatase in breast cancer cells. Toxicol Sci 2006; 92:71-7. [PMID: 16611627 DOI: 10.1093/toxsci/kfj190] [Citation(s) in RCA: 89] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Estrogen plays a crucial role in the development of breast cancer, and the inhibition of estrogen synthesis has been an important target for the prevention and treatment of this disease. The rate-limiting reaction of the hormone biosynthesis is catalyzed by cytochrome P450 (CYP) 19 enzyme or aromatase. It has been of genuine interest to uncover an aromatase-inhibitory compound from a dietary source. Resveratrol is a polyphenolic compound that can be isolated from grape peel. Because of its structural resemblance to estrogen, resveratrol's agonistic and antagonistic properties on estrogen receptor have been examined and demonstrated. In the present study, the effect of resveratrol on the expression and enzyme activity of aromatase was investigated. By assaying on MCF-7 cells stably transfected with CYP19 (MCF-7aro cells), resveratrol inhibited the aromatase activity with an IC(50) value of 25 microM. Kinetic analysis indicated that both competitive and noncompetitive inhibition might be involved. The administration of 10 nmol/l testosterone-a substrate of aromatase-produced a 50% increase in the MCF-7aro cell number. This cell proliferation specifically induced by testosterone was significantly reduced by 10 microM resveratrol. In addition, 50 microM resveratrol significantly reduced the CYP19-encoding mRNA abundance in SK-BR-3 cells. The transcriptional control of CYP19 gene is tissue specific, and promoter regions I.3 and II have previously been shown to be responsible for CYP19 expression in breast cancer cells. Luciferase reporter gene assays revealed that resveratrol could repress the transcriptional control dictated by the promoter regulation. The present study illustrated that pharmacological dosage of resveratrol inhibited aromatase at both the enzyme and mRNA levels.
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Affiliation(s)
- Yun Wang
- Department of Biochemistry and Department of Anatomy, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong
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Wang Y, Chan FL, Chen S, Leung LK. The plant polyphenol butein inhibits testosterone-induced proliferation in breast cancer cells expressing aromatase. Life Sci 2005; 77:39-51. [PMID: 15848217 DOI: 10.1016/j.lfs.2004.12.014] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2004] [Accepted: 12/10/2004] [Indexed: 10/25/2022]
Abstract
Chalcones are precursor compounds for flavonoid synthesis in plants, and they can also be synthesized in laboratory. Previous study has documented some of the pharmacological applications of these compounds. Estrogen has long been associated with the initiation and promotion of breast cancer. Inhibiting estrogen synthesis can be effective in the prevention and treatment of the disease. Since most breast cancers received estrogen supplied from local tissues, we employed a breast cancer cell line expressing aromatase to screen for the inhibitory potentials of five hydroxychalcones, i.e. 2-hydroxychalcone, 2'-hydroxychalcone, 4-hydroxychalcone, 4,2',4'-trihydroxy-chalcone (isoquiritigenin), 3,4,2',4'-tetrahydroxychalcone (butein). In the preliminary results, butein was found to be the strongest inhibitor among the tested compounds, and its IC(50) value was 3.75 microM. Subsequent enzyme kinetic study revealed that butein acted on aromatase with a mixed type of inhibition and the K(i) value was determined to be 0.32 microM. Cell proliferation assay indicated that the cell number increased by 10 nM-testosterone treatment was significantly reduced by 5 microM butein, and the administration of flutamide could not reverse the effect. The present study illustrated that butein was an aromatase inhibitor and a potential natural alternative for the chemoprevention or therapy of breast cancer.
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Affiliation(s)
- Yun Wang
- Department of Biochemistry, The Chinese University of Hong Kong, Rm. 507C MMW Bldg., Shatin, N.T., Hong Kong
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Wang H, Wang Y, Chen ZY, Chan FL, Leung LK. Hydroxychalcones exhibit differential effects on XRE transactivation. Toxicology 2005; 207:303-13. [PMID: 15596260 DOI: 10.1016/j.tox.2004.10.005] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2004] [Revised: 10/12/2004] [Accepted: 10/12/2004] [Indexed: 11/29/2022]
Abstract
Chalcones are phenolic compounds that can be isolated from plants. Previous studies have described some pharmacological applications for these compounds. Making use of our established reporter gene system, we determined the effect of five hydroxychalcones--2-hydroxychalcone, 2'-hydroxychalcone, 4-hydroxychalcone, 4,2',4'-trihydroxychalcone, and 3,4,2',4'-tetrahydroxychalcone--on the cellular xenobiotic responsive element (XRE)-transactivation. The interference of chalcones acting against polycyclic aromatic hydrocarbon (PAH)-DNA binding was also examined. Enzyme inhibition assays of cytochrome P450 (CYP) 1A1 and CYP1B1 were initially performed on recombinant protein expressed in insect microsomes. 2'-Hydroxychalcone and 2-hydroxychalcone were the most effective among the tested hydroxychalcones. The two hydroxychalcones had comparable IC50 values for CYP1A1 and CYP1B1, which were determined to be at the micromolar and submicromolar range, respectively. However, reporter gene assays indicated that 2'-hydroxychalcone suppressed XRE-transactivation, whereas 2-hydroxychalcone induced it when 7,12-dimethylbenz[a]anthracene (DMBA) was co-administered. In the absence of DMBA, 10 microM 2-hydroxychalcone and 2'-hydroxychalcone increased XRE-transactivation by 18- and 2.5-fold, respectively, while other chalcones did not significantly alter the response. Cultures treated with the two hydroxychalcones also displayed separate trends in ethoxyresorufin-O-deethylase (EROD) activity and DMBA-DNA covalent binding. In summary, the present study illustrated that the inhibition of hydroxychalcone on CYP1 enzymes and XRE-transactivation was affected by the position and number of hydroxyl groups in its structure.
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Affiliation(s)
- Huan Wang
- Food and Nutritional Sciences Programme, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong
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Chan HY, Wang H, Tsang DSC, Chen ZY, Leung LK. Screening of chemopreventive tea polyphenols against PAH genotoxicity in breast cancer cells by a XRE-luciferase reporter construct. Nutr Cancer 2004; 46:93-100. [PMID: 12925309 DOI: 10.1207/s15327914nc4601_12] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022]
Abstract
Polycyclic aromatic hydrocarbons (PAHs) are established cancer initiators that can be found in our food and environment. Some dietary plant polyphenols are strong inhibitors to PAH-induced mutagenesis, whereas others may not be as effective. To identify the chemopreventive compounds from a huge volume of dietary components, the development of an efficient screening method is required. In this study, a xenobiotic response element (XRE)-luciferase reporter plasmid was constructed to screen for some potential chemopreventive agents in tea against PAH-induced DNA damage. Tea is one of the most consumed beverages worldwide, and its beneficial effects on health have been documented. Previous studies have claimed that tea polyphenols could be protective against various cancers, and the rich database can be a source for comparison. Among the green and black tea polyphenols, the XRE-luciferase reporter assays suggested that only epigallocatechin gallate (EGCG) was effective in reducing XRE-driven luciferase assay in MCF-7 cells at the concentrations tested. Further study indicated EGCG could reduce CYP1A1 and CYP1B1 mRNA abundances and decrease the DMBA-DNA lesions. The results of DNA covalent binding of all tea polyphenols tested were consistent with the XRE-reporter assays. This study illustrated that the XRE-reporter assay was a viable screening test for dietary chemopreventive agents against PAH-initiated breast mutagenesis. It has the advantages of shorter sample processing time and producing no radioactive waste over directly measuring the CYP1A1/1B1 expressions, DNA lesion, or gel mobility shift assay.
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Affiliation(s)
- Ho Yee Chan
- Department of Biochemistry, Faculty of Medicine, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong
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Abstract
Epidemiological studies indicate that Asian women have a lower breast cancer incidence compared with their counterparts in the West, and the difference has been related to soya consumption. Animal studies have suggested that soya may prevent dimethylbenz[a]anthracene (DMBA)-induced carcinogenesis in the breast. In the present study a cell culture model was developed to address the effect of soya isoflavones on the DMBA-induced DNA damage. DMBA is metabolized into a DNA-attacking moiety by two phase I cytochrome P450 (CYP) enzymes CYP1A1 and CYP1B1. DNA mutation caused by this genotoxic agent is a crucial step in cancer initiation. Substances that interfere with the CYP1 enzyme activities can affect the initiation. In the present study, genistein was found to be an effective inhibitor of recombinant human CYP1A1 and CYP1B1 with Ki of 15.35 and 0.68 micromol/l. The other soya isoflavone daidzein, on the other hand, did not demonstrate any significant inhibition of the enzyme activities. At the transcriptional level, DMBA induced the CYP1 enzyme expressions by stimulating the xenobiotic response element (XRE)-dependent transactivation pathway. When genistein (25 micromol/l) was co-administered with DMBA, the XRE-Luc activity the CYP1 mRNA abundances were significantly suppressed. The present study illustrated that the soya isoflavone genistein, but not daidzein, protected against DMBA genotoxicity.
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Affiliation(s)
- Ho Yee Chan
- Department of Biochemistry, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong
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Chan HY, Wang H, Leung LK. The red clover (Trifolium pratense) isoflavone biochanin A modulates the biotransformation pathways of 7,12-dimethylbenz[a]anthracene. Br J Nutr 2003; 90:87-92. [PMID: 12844379 DOI: 10.1079/bjn2003868] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Several flavonoids have shown their anti-carcinogenic effects in various models. The soyabean isoflavone genistein was demonstrated earlier in our laboratory to be an effective inhibitor of dimethylbenz[a]anthracene (DMBA)-induced DNA damage in MCF-7 cells by curbing cytochrome P450 (CYP) 1 enzymes. The red clover (Trifolium pratense) isoflavone biochanin A is a methylated derivative of genistein, and its anti-mutagenic effect in bacterial cells has been shown previously. Because of its protection against chemical carcinogenesis in an animal model, biochanin A was selected for testing in our established MCF-7 cell system. From the results obtained in the semi-quantitative reverse transcription-polymerase chain reaction and xenobiotic response element (XRE)-luciferase reporter assays, biochanin A could reduce xenobiotic-induced CYP1A1 and -1B1 mRNA abundances through the interference of XRE-dependent transactivation. Enzyme kinetic studies also indicated that biochanin A inhibited both CYP1A1 and -1B1 enzymes with inhibition constant (Ki) values 4.00 and 0.59 microm respectively. Since the biotransformation of DMBA was dependent on CYP1 enzyme activities, biochanin A was able to decrease the DMBA-DNA lesions. The present study illustrated that the red clover isoflavone could protect against polycylic aromatic hydrocarbon-induced DNA damage.
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Affiliation(s)
- Ho Yee Chan
- Department of Biochemistry, Faculty of Medicine, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong
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