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Escudero-Lourdes C, Alvarado-Morales I, Tokar EJ. Stem Cells as Target for Prostate cancer Therapy: Opportunities and Challenges. Stem Cell Rev Rep 2022. [PMID: 35951166 DOI: 10.1007/s12015-022-10437-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/24/2022] [Indexed: 10/15/2022]
Abstract
Cancer stem cells (CSCs) and cells in a cancer stem cell-like (CSCL) state have proven to be responsible for tumor initiation, growth, and relapse in Prostate Cancer (PCa) and other cancers; therefore, new strategies are being developed to target such cellular populations. TLR3 activation-based immunotherapy using Polyinosinic:Polycytidylic acid (PIC) has been proposed to be used as a concomitant strategy to first-line treatment. This strategy is based on the induction of apoptosis and an inflammatory response in tumor cells. In combination with retinoids like 9cRA, this treatment can induce CSCs differentiation and apoptosis. A limitation in the use of this combination is the common decreased expression of TLR3 and its main positive regulator p53. observed in many patients suffering of different cancer types such as PCa. Importantly, human exposure to certain toxicants, such as iAs, not only has proven to enrich CSCs population in an in vitro model of human epithelial prostate cells, but additionally, it can also lead to a decreased p53, TLR3 and RA receptor (RARβ), expression/activation and thus hinder this treatment efficacy. Therefore, here we point out the relevance of evaluating the TLR3 and P53 status in PCa patients before starting an immunotherapy based on the use of PIC +9cRA to determine whether they will be responsive to treatment. Additionally, the use of strategies to overcome the lower TLR3, RARβ or p53 expression in PCa patients, like the inclusion of drugs that increase p53 expression, is encouraged, to potentiate the use of PIC+RA based immunotherapy in these patients.
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Khalique A, Mohammed AK, Al-khadran NM, Gharaibeh MA, Abu-Gharbieh E, El-Huneidi W, Sulaiman N, Taneera J. Reduced Retinoic Acid Receptor Beta ( Rarβ) Affects Pancreatic β-Cell Physiology. Biology (Basel) 2022; 11:biology11071072. [PMID: 36101450 PMCID: PMC9312298 DOI: 10.3390/biology11071072] [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] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/07/2022] [Revised: 07/15/2022] [Accepted: 07/15/2022] [Indexed: 12/02/2022]
Abstract
Various studies have suggested a link between vitamin A (VA), all-trans-retinol, and type 2 diabetes (T2D). However, the functional role/expression of vitamin A receptors (Rarα, β, and γ) in pancreatic β-cells is not clear yet. Accordingly, we performed a series of bioinformatics, molecular and functional experiments in human islet and INS-1 cells to evaluate the role of Rarβ on insulin secretion and pancreatic β-cell function. Microarray and RNA-sequencing (RAN-seq) expression analysis showed that RARα, β, and γ are expressed in human pancreatic islets. RNA-seq expression of RARβ in diabetic/hyperglycemic human islets (HbA1c ≥ 6.3%) revealed a significant reduction (p = 0.004) compared to nondiabetic/normoglycemic cells (HbA1c < 6%). The expression of RARβ with INS and PDX1 showed inverse association, while positive correlations were observed with INSR and HbA1c levels. Exploration of the T2D knowledge portal (T2DKP) revealed that several genetic variants in RARβ are associated with BMI. The most associated variant is rs6804842 (p = 1.2 × 10−25). Silencing of Rarβ in INS-1 cells impaired insulin secretion without affecting cell viability or apoptosis. Interestingly, reactive oxygen species (ROS) production levels were elevated and glucose uptake was reduced in Rarβ-silenced cells. mRNA expression of Ins1, Pdx1, NeuroD1, Mafa, Snap25, Vamp2, and Gck were significantly (p < 0.05) downregulated in Rarβ-silenced cells. For protein levels, Pro/Insulin, PDX1, GLUT2, GCK, pAKT/AKT, and INSR expression were downregulated considerably (p < 0.05). The expression of NEUROD and VAMP2 were not affected. In conclusion, our results indicate that Rarβ is an important molecule for β-cell function. Hence, our data further support the potential role of VA receptors in the development of T2D.
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Affiliation(s)
- Anila Khalique
- Sharjah Institute for Medical Research, University of Sharjah, Sharjah 27272, United Arab Emirates; (A.K.); (A.K.M.); (M.A.G.); (E.A.-G.); (W.E.-H.)
| | - Abdul Khader Mohammed
- Sharjah Institute for Medical Research, University of Sharjah, Sharjah 27272, United Arab Emirates; (A.K.); (A.K.M.); (M.A.G.); (E.A.-G.); (W.E.-H.)
| | - Nujood Mohammed Al-khadran
- Department of Basic Medical Sciences, College of Medicine, University of Sharjah, Sharjah 27272, United Arab Emirates;
| | - Mutaz Al Gharaibeh
- Sharjah Institute for Medical Research, University of Sharjah, Sharjah 27272, United Arab Emirates; (A.K.); (A.K.M.); (M.A.G.); (E.A.-G.); (W.E.-H.)
| | - Eman Abu-Gharbieh
- Sharjah Institute for Medical Research, University of Sharjah, Sharjah 27272, United Arab Emirates; (A.K.); (A.K.M.); (M.A.G.); (E.A.-G.); (W.E.-H.)
- Department of Clinical Sciences, College of Medicine, University of Sharjah, Sharjah 27272, United Arab Emirates
| | - Waseem El-Huneidi
- Sharjah Institute for Medical Research, University of Sharjah, Sharjah 27272, United Arab Emirates; (A.K.); (A.K.M.); (M.A.G.); (E.A.-G.); (W.E.-H.)
- Department of Basic Medical Sciences, College of Medicine, University of Sharjah, Sharjah 27272, United Arab Emirates;
| | - Nabil Sulaiman
- Department of Family Medicine, College of Medicine, University of Sharjah, Sharjah 27272, United Arab Emirates;
| | - Jalal Taneera
- Sharjah Institute for Medical Research, University of Sharjah, Sharjah 27272, United Arab Emirates; (A.K.); (A.K.M.); (M.A.G.); (E.A.-G.); (W.E.-H.)
- Department of Basic Medical Sciences, College of Medicine, University of Sharjah, Sharjah 27272, United Arab Emirates;
- Correspondence: ; Tel.: +97-165-057-743
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Zhang X, Cong Y, Chu Z, Shi L, Zheng Y, Zhao Q, Geng S, Guo K. Aberrant epigenetic regulation of RARβ by TET2 is involved in cutaneous squamous cell carcinoma resistance to retinoic acid. Int J Biochem Cell Biol 2022; 145:106190. [PMID: 35248720 DOI: 10.1016/j.biocel.2022.106190] [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: 11/12/2021] [Revised: 02/14/2022] [Accepted: 03/01/2022] [Indexed: 10/18/2022]
Abstract
OBJECTIVES With the growing incidence of cutaneous squamous cell carcinoma (CSCC), the treatment-resistant invasive CSCC should be taken seriously. Retinoic acid receptor β (RARβ) functions as a tumor suppressor gene and is associated with the proliferation inhibition to retinoic acid. Demethylase TET2 directed epigenetic landscape contributes to cell malignant transform and is involved in therapeutic resistance in tumors. Whether aberrant TET2 participated in the deficient RARβ remains largely unknown. Hereby, we identified the aberrant-TET2 directed epigenetic landscape contribute to the deficient RARβ in CSCC. METHODS The immunohistochemistry was used to detect the expression of RARβ and TET2. The bisulfite sequencing PCR was used to detect the RARβ promoter methylation. Plasmid transfection was used to upregulate TET2 in CSCC cells. Stable overxpressed TET2 cells were used to detect the effect of TET2 on RARβ and drug sensitivity in the CCSC. RESULTS We observed RARβ decreased with promoter hypermethylation in CSCC and aberrant TET2 associated with deficient RARβ. We upregulated TET2 could reverse promoter hypermethylation and showed a significantly increased expression of RARβ, which enhanced the sensitivity of tumor cells to retinoic acid treatment. CONCLUSION Aberrant TET2 leaded to the hypermethylation of RARβ promoter, which contributed to the deficient RARβ in CSCC. While reversing the hypermethylation of the RARβ promoter by recovering the TET2 could enhance tumor cells to be sensitive to retinoic acid.
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Affiliation(s)
- Xinyue Zhang
- Department of Dermatology, The Second Hospital Affiliated Hospital, School of Medicine, Xi'an Jiaotong University, Xi'an 710004, China
| | - Yan Cong
- Department of Dermatology, The Second Hospital Affiliated Hospital, School of Medicine, Xi'an Jiaotong University, Xi'an 710004, China
| | - Zhaowei Chu
- Department of Dermatology, The Second Hospital Affiliated Hospital, School of Medicine, Xi'an Jiaotong University, Xi'an 710004, China
| | - Linjing Shi
- Department of Dermatology, The Second Hospital Affiliated Hospital, School of Medicine, Xi'an Jiaotong University, Xi'an 710004, China
| | - Yi Zheng
- Department of Dermatology, The Second Hospital Affiliated Hospital, School of Medicine, Xi'an Jiaotong University, Xi'an 710004, China
| | - Qiang Zhao
- Department of Dermatology, The Second Hospital Affiliated Hospital, School of Medicine, Xi'an Jiaotong University, Xi'an 710004, China
| | - Songmei Geng
- Department of Dermatology, The Second Hospital Affiliated Hospital, School of Medicine, Xi'an Jiaotong University, Xi'an 710004, China.
| | - Kun Guo
- Department of Dermatology, The Second Hospital Affiliated Hospital, School of Medicine, Xi'an Jiaotong University, Xi'an 710004, China.
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Alvarado-Morales I, Olivares-Illana V, Arenas-Huertero C, Reynaga-Hernández E, Layseca-Espinosa E, Tokar EJ, Escudero-Lourdes C. Human prostate epithelial cells and prostate-derived stem cells malignantly transformed in vitro with sodium arsenite show impaired Toll like receptor -3 (TLR3)-associated anti-tumor pathway. Toxicol Lett 2021; 350:185-193. [PMID: 34303791 PMCID: PMC8410676 DOI: 10.1016/j.toxlet.2021.07.013] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2021] [Revised: 07/13/2021] [Accepted: 07/19/2021] [Indexed: 02/08/2023]
Abstract
A therapeutic strategy for prostate cancer (PCa) involves the use of 9-cis-retinoic acid (9cRA) to induce cancer stem cells (CSCs) differentiation and apoptosis. Polyinosinic:polycytidylic acid (PIC) is a Toll-like receptor 3 (TLR3) agonist that induces tumor cells apoptosis after activation. PIC+9cRA combination activates retinoic acid receptor β (RARβ) re-expression, leading to CSC differentiation and growth arrest. Since inorganic arsenic (iAs) targets prostatic stem cells (SCs), we hypothesized that arsenic-transformed SCs (As-CSCs) show an impaired TLR3-associated anti-tumor pathway and, therefore, are unresponsive to PIC activation. We evaluated TLR3-mediated activation of anti-tumor pathway based in RARβ expression, on As-CSC and iAs-transformed epithelial cells (CAsE-PE). As-CSCs and CAsE-PE showed lower TLR3 and RARβ basal expression compared to their respective isogenic controls WPE-Stem and RWPE-1. Also, iAs transformants showed reduced expression of mediators in TLR3 pathway. Importantly, As-CSCs were irresponsive to PIC+9cRA in terms of increased RARβ and decreased SC-markers expression, while CAsE-PE, a heterogeneous cell line having a small SC population, were partially responsive. These observations indicate that iAs can impair TLR3 expression and anti-tumor pathway activated by PIC+9cRA in SCs and prostatic epithelial cells. These findings suggest that TLR3-activation based therapy may be an ineffective therapeutic alternative for iAs-associated PCa.
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Affiliation(s)
- I Alvarado-Morales
- Laboratorio de Inmunotoxicología. Facultad de Ciencias Químicas, Universidad Autónoma de San Luis Potosí, Manuel Nava 6, Zona Universitaria, 78290, SLP, Mexico
| | - V Olivares-Illana
- Laboratorio de Interacciones Biomoleculares y Cáncer, Instituto de Física, Universidad Autónoma de San Luis Potosí, Manuel Nava 6, Zona Universitaria, 78290, SLP, Mexico
| | - C Arenas-Huertero
- Laboratorio de Biología, Facultad de Ciencias, Universidad Autónoma de San Luis Potosí. Av, Chapultepec, 1570. 78295, SLP, Mexico
| | - E Reynaga-Hernández
- Laboratorio de Inmunotoxicología. Facultad de Ciencias Químicas, Universidad Autónoma de San Luis Potosí, Manuel Nava 6, Zona Universitaria, 78290, SLP, Mexico
| | - E Layseca-Espinosa
- Centro de Investigación en Biomedicina y Salud, Facultad de Medicina, Universidad autónoma de San Luis Potosí, Sierra Leona 550 Lomas de San Luis, 78210, SLP, Mexico
| | - E J Tokar
- National Toxicology Program Laboratory, NTP. National Institutitute of Environmental Health Sciences, NIEHS, Durham, NC, 27709, United States
| | - C Escudero-Lourdes
- Laboratorio de Inmunotoxicología. Facultad de Ciencias Químicas, Universidad Autónoma de San Luis Potosí, Manuel Nava 6, Zona Universitaria, 78290, SLP, Mexico.
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Radhakrishnan R, Crane HL, Daigneault M, Padam KSR, Hunter KD. RARβ Expression in Keratinocytes from Potentially Malignant Oral Lesions: The Functional Consequences of Re-Expression by De-Methylating Agents. Cancers (Basel) 2021; 13:4064. [PMID: 34439217 DOI: 10.3390/cancers13164064] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2021] [Revised: 08/06/2021] [Accepted: 08/11/2021] [Indexed: 12/03/2022] Open
Abstract
Simple Summary Patients may develop white or red patches of the lining of the mouth with an increased risk of developing oral cancer. Treatment with Vitamin A derivatives (retinoids) results in some improvement in these lesions, but this is not maintained, and there are side effects. We know that the cells of the mouth lose cellular receptors for retinoids as these lesions develop, initially by a reversible alteration to the DNA (DNA methylation). Drugs, such as 5-AZA-CdR, which reduce DNA methylation, may restore sensitivity to the effects of retinoids. Treatment of a panel of cells from mouth precancer white patches with retinoids, 5-AZA-CdR and a combination results in varied responses: some cells re-sensitise to retinoids, whereas in others, the main effects on cell division rate and cell lifespan seem related to the effects of 5-AZA-CdR alone. These findings help us to understand the varied responses to retinoids in the clinical setting. Abstract Loss of RARβ2 expression by promoter methylation is an early event in oral carcinogenesis. Understanding the mechanisms and consequences of RARβ loss may aid in understanding the disappointing results of retinoid chemoprevention trials. This study aimed to describe the effects of all-trans retinoic acid (ATRA) and the de-methylating agent 5-Aza-2′ deoxycytidine (5-AZA-CdR) on a panel of immortal potentially malignant oral lesion (PMOL) cell cultures. RARβ expression was assessed in PMOL tissues by immunohistochemistry. Cells were treated with ATRA ± 5-AZA-CdR, and the effects on the cell cycle and senescence were assessed. In PMOL tissues, RARβ expression was variable, but lower in biopsies which gave rise to immortal cell cultures. Treatment of iPMOL cells with ATRA resulted in little change in RARβ expression, but the addition of 5-AZA-CdR resulted in significant increases. The effects on the cell cycle and senescence were variable and may be related to 5-AZA-CdR, as this has wider effects on the cell cycle. Overall, the response of iPMOL cells to ATRA and 5-AZA-CdR treatment was variable and is dependent on several factors, including RARβ-promoter methylation. These findings may help to explain the lack of consistent effect of retinoids in PMOLs seen in chemoprevention trials.
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Abdelwahab EMM, Bovari-Biri J, Smuk G, Harko T, Fillinger J, Moldvay J, Krymskaya VP, Pongracz JE. Normalization of Enzyme Expression and Activity Regulating Vitamin A Metabolism Increases RAR-Beta Expression and Reduces Cellular Migration and Proliferation in Diseases Caused by Tuberous Sclerosis Gene Mutations. Front Oncol 2021; 11:644592. [PMID: 34178631 PMCID: PMC8226169 DOI: 10.3389/fonc.2021.644592] [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] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2020] [Accepted: 05/25/2021] [Indexed: 11/15/2022] Open
Abstract
Background Mutation in a tuberous sclerosis gene (TSC1 or 2) leads to continuous activation of the mammalian target of rapamycin (mTOR). mTOR activation alters cellular including vitamin A metabolism and retinoic acid receptor beta (RARβ) expression. The goal of the present study was to investigate the molecular connection between vitamin A metabolism and TSC mutation. We also aimed to investigate the effect of the FDA approved drug rapamycin and the vitamin A metabolite retinoic acid (RA) in cell lines with TSC mutation. Methods Expression and activity of vitamin A associated metabolic enzymes and RARβ were assessed in human kidney angiomyolipoma derived cell lines, primary lymphangioleiomyomatosis (LAM) tissue derived LAM cell lines. RARβ protein levels were also tested in primary LAM lung tissue sections. TaqMan arrays, enzyme activities, qRT-PCRs, immunohistochemistry, immunofluorescent staining, and western blotting were performed and analysed. The functional effects of retinoic acid (RA) and rapamycin were tested in a scratch and a BrDU assay to assess cell migration and proliferation. Results Metabolic enzyme arrays revealed a general deregulation of many enzymes involved in vitamin A metabolism including aldehyde dehydrogenases (ALDHs), alcohol dehydrogenases (ADHs) and Cytochrome P450 2E1 (CYP2E1). Furthermore, RARβ downregulation was a characteristic feature of all TSC-deficient cell lines and primary tissues. Combination of the two FDA approved drugs -RA for acute myeloid leukaemia and rapamycin for TSC mutation- normalised ALDH and ADH expression and activity, restored RARβ expression and reduced cellular proliferation and migration. Conclusion Deregulation of vitamin A metabolizing enzymes is a feature of TSC mutation. RA can normalize RARβ levels and limit cell migration but does not have a significant effect on proliferation. Based on our data, translational studies could confirm whether combination of RA with reduced dosage of rapamycin would have more beneficial effects to higher dosage of rapamycin monotherapy meanwhile reducing adverse effects of rapamycin for patients with TSC mutation.
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Affiliation(s)
| | - Judit Bovari-Biri
- Departments of Pharmaceutical Biotechnology, University of Pecs, Pecs, Hungary.,Szentagothai Research Centre, University of Pecs, Pecs, Hungary
| | - Gabor Smuk
- Department of Pathology, University of Pecs, Pecs, Hungary
| | - Tunde Harko
- Department of Pathology, Semmelweis University, Budapest, Hungary
| | - Janos Fillinger
- Department of Pathology, Semmelweis University, Budapest, Hungary.,Department of Pulmonology, National Koranyi Institute of Pulmonology, Budapest, Hungary
| | - Judit Moldvay
- Department of Pathology, Semmelweis University, Budapest, Hungary.,Department of Pulmonology, National Koranyi Institute of Pulmonology, Budapest, Hungary
| | - Vera P Krymskaya
- Pulmonary, Allergy and Critical Care Division, Department of Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, United States
| | - Judit E Pongracz
- Departments of Pharmaceutical Biotechnology, University of Pecs, Pecs, Hungary.,Szentagothai Research Centre, University of Pecs, Pecs, Hungary
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Goncalves MB, Wu Y, Clarke E, Grist J, Hobbs C, Trigo D, Jack J, Corcoran JPT. Regulation of Myelination by Exosome Associated Retinoic Acid Release from NG2-Positive Cells. J Neurosci 2019; 39:3013-27. [PMID: 30760627 DOI: 10.1523/JNEUROSCI.2922-18.2019] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2018] [Revised: 01/15/2019] [Accepted: 02/03/2019] [Indexed: 02/07/2023] Open
Abstract
In the CNS, oligodendrocytes are responsible for myelin formation and maintenance. Following spinal cord injury, oligodendrocyte loss and an inhibitory milieu compromise remyelination and recovery. Here, we explored the role of retinoic acid receptor-beta (RARβ) signaling in remyelination. Using a male Sprague Dawley rat model of PNS-CNS injury, we show that oral treatment with a novel drug like RARβ agonist, C286, induces neuronal expression of the proteoglycan decorin and promotes myelination and differentiation of oligodendrocyte precursor cells (NG2+ cells) in a decorin-mediated neuron–glia cross talk. Decorin promoted the activation of RARα in NG2+ cells by increasing the availability of the endogenous ligand RA. NG2+ cells synthesize RA, which is released in association with exosomes. We found that decorin prevents this secretion through regulation of the EGFR–calcium pathway. Using functional and pharmacological studies, we further show that RARα signaling is both required and sufficient for oligodendrocyte differentiation. These findings illustrate that RARβ and RARα are important regulators of oligodendrocyte differentiation, providing new targets for myelination. SIGNIFICANCE STATEMENT This study identifies novel therapeutic targets for remyelination after PNS-CNS injury. Pharmacological and knock-down experiments show that the retinoic acid (RA) signaling promotes differentiation of oligodendrocyte precursor cells (OPCs) and remyelination in a cross talk between neuronal RA receptor-beta (RARβ) and RARα in NG2+ cells. We show that stimulation of RARα is required for the differentiation of OPCs and we describe for the first time how oral treatment with a RARβ agonist (C286, currently being tested in a Phase 1 trial, ISRCTN12424734) leads to the endogenous synthesis of RA through retinaldehyde dehydrogenase 2 (Raldh2) in NG2 cells and controls exosome-associated-RA intracellular levels through a decorin–Ca2+ pathway. Although RARβ has been implicated in distinct aspects of CNS regeneration, this study identifies a novel function for both RARβ and RARα in remyelination.
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Li Y, Lu DG, Ma YM, Liu H. Association between Retinoic acid receptor-β hypermethylation and NSCLC risk: a meta-analysis and literature review. Oncotarget 2017; 8:5814-22. [PMID: 28008143 DOI: 10.18632/oncotarget.14023] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2016] [Accepted: 12/12/2016] [Indexed: 02/06/2023] Open
Abstract
Emerging evidence indicates that Retinoic acid receptor-β (RARβ) is a tumor suppressor in many types of tumor. However, whether or not RARβ is a risk factor and is correlated to clinicopathological characteristics of non-small cell lung cancer (NSCLC) remains unclear. In this report, we performed a meta-analysis to determine the effects of RARβ hypermethylation on the incidence of NSCLC and clinicopathological characteristics in human NSCLC patients. Final valuation and analysis of 1780 cancer patients from 16 eligible studies was performed. RARβ hypermethylation was found to be significantly higher in NSCLC than in normal lung tissue, the pooled OR from 7 studies including 646 NSCLC and 580 normal lung tissues, OR = 6.05, 95% CI = 3.56-10.25, p<0.00001. RARβ hypermethylation was significantly higher in adenocarcinoma (AC) compared to squamous cell carcinoma (SCC), pooled OR is 0.68 (95% CI = 0.52-0.89, p = 0.005). RARβ hypermethylation was also found to occur significantly higher in smoker (n = 232) than non-smoker (n = 213) (OR = 2.46, 95% CI = 1.54-3.93, p = 0.0002). Our results indicate that RARβ hypermethylation correlates well with an increased risk in NSCLC patients. RARβ geneinactivation caused by RARβ methylation contributes the NSCLC tumorigenesis and may serve as a potential risk factor, diagnostic marker and drug target of NSCLC.
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Shu R, He J, Wu C, Gao J. The association between RARβ and FHIT promoter methylation and the carcinogenesis of patients with cervical carcinoma: A meta-analysis. Tumour Biol 2017. [PMID: 28639889 DOI: 10.1177/1010428317709126] [Citation(s) in RCA: 7] [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] [Indexed: 12/26/2022] Open
Abstract
The RARβ and FHIT promoter methylation are observed in some cervical carcinoma. However, the association between RARβ and FHIT promoter methylation and cervical carcinogenesis remains unclear. This study was carried out to evaluate the correlation between RARβ or FHIT promoter methylation and cervical carcinogenesis. Eligible publications were searched via online databases. The combined odds ratios and corresponding 95% confidence intervals were calculated and summarized. In all, 17 eligible articles on RARβ and FHIT promoter methylation were identified in the study. RARβ promoter methylation was significantly higher in cervical cancer than in cervical intraepithelial neoplasia lesions and normal cervical tissues (odds ratio = 3.90, p = 0.018; odds ratio = 12.98, p < 0.001, respectively). There was more FHIT promoter methylation in cervical cancer than in cervical intraepithelial neoplasia lesions and normal controls (odds ratio = 8.0, p = 0.055; odds ratio = 10.75, p < 0.001, respectively). In addition, FHIT promoter methylation was correlated with clinical stage (advanced stage vs early stage: odds ratio = 2.69, p = 0.056) and tumor grade (high grade vs low grade: odds ratio = 4.11, p < 0.001). RARβ and FHIT promoter methylation may be associated with the carcinogenesis of cervical cancer. FHIT promoter methylation may play a crucial role in cervical cancer progression. Additional studies with large sample sizes are essential to confirm our findings.
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Affiliation(s)
- Ruming Shu
- Department of Gynaecology and Obstetrics, The Third Affiliated Hospital of Nanchang University, Nanchang, China
| | - Jie He
- Department of Gynaecology and Obstetrics, The Third Affiliated Hospital of Nanchang University, Nanchang, China
| | - Chengzhen Wu
- Department of Gynaecology and Obstetrics, The Third Affiliated Hospital of Nanchang University, Nanchang, China
| | - Jun Gao
- Department of Gynaecology and Obstetrics, The Third Affiliated Hospital of Nanchang University, Nanchang, China
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Yu DJ, Wang XJ, Shi YF, Jiang CY, Zhao RZ, Zhu YP, Chen L, Yang YQ, Sun XW, Xia SJ. Macrophages are targets of retinoic acid signaling during the wound-healing process after thulium laser resection of the prostate. Oncotarget 2017; 8:71996-72007. [PMID: 29069763 PMCID: PMC5641106 DOI: 10.18632/oncotarget.18238] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [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: 03/13/2017] [Accepted: 05/10/2017] [Indexed: 01/19/2023] Open
Abstract
BACKGROUND The wound-healing process is very important for reducing complications after thulium laser resection of the prostate (TmLRP). The retinoic acid (RA) signaling pathway has been well studied in the wound-healing process of the skin and other organs. The goals of this study were to identify the role of RA signaling in the repair of the prostate after TmLRP and to investigate the molecular mechanism of this process. RESULTS Retinoic acid receptors (RARs) were present in the prostate, and their expression was increased after TmLRP. RARβ was expressed in the macrophages and may be related to the role of stromal cells in the wound-healing process. In vitro, RA enhanced the function of anti-inflammatory macrophages and promoted stromal cell activation and angiogenesis. Arg1 was also increased via RARβ after treatment with RA. MATERIALS AND METHODS The expression of RARs was analyzed in vivo by immunohistochemistry (IHC), real time qPCR, and western blot analysis. THP-1 cells were co-treated with or without RA and stimulating factor and then assessed by ELISA and qPCR. The supernatants from these cells were cultured with stromal cells and vascular endothelial cells, and the effects on these cells were analyzed. CONCLUSIONS We found that RA signaling was involved in the wound-healing process of the prostate after TmLRP. RA treated macrophages activated stromal cells and promoted angiogenesis. RARβ was the key isoform in this process.
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Affiliation(s)
- Dian-Jun Yu
- Department of Urology, Shanghai General Hospital of Nanjing Medical University, Shanghai 200080, China.,Department of Urology, Ningbo Medical Center Lihuili Eastern Hospital, Ningbo 315048, China
| | - Xing-Jie Wang
- Department of Urology, Shanghai General Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 200080, China
| | - Yun-Feng Shi
- Department of Urology, Shanghai General Hospital of Nanjing Medical University, Shanghai 200080, China.,Department of Urology, Wujin Hospital Affiliated Jiang Su University, Changzhou 213302, China
| | - Chen-Yi Jiang
- Department of Urology, Shanghai General Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 200080, China
| | - Rui-Zhe Zhao
- Department of Urology, Shanghai General Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 200080, China
| | - Yi-Ping Zhu
- Department of Urology, Shanghai General Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 200080, China
| | - Li Chen
- Department of Urology, Ningbo Medical Center Lihuili Eastern Hospital, Ningbo 315048, China
| | - Yuan-Qing Yang
- Department of Urology, Ningbo Medical Center Lihuili Eastern Hospital, Ningbo 315048, China
| | - Xiao-Wen Sun
- Department of Urology, Shanghai General Hospital of Nanjing Medical University, Shanghai 200080, China.,Department of Urology, Shanghai General Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 200080, China.,Institute of Urology, Shanghai Jiao Tong University, Shanghai 200080, China
| | - Shu-Jie Xia
- Department of Urology, Shanghai General Hospital of Nanjing Medical University, Shanghai 200080, China.,Department of Urology, Shanghai General Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 200080, China.,Institute of Urology, Shanghai Jiao Tong University, Shanghai 200080, China
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11
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Song X, Shi K, Zhou SJ, Yu DP, Liu Z, Han Y. Clinicopathological significance and a potential drugtarget of RARβ in non-small-cell lung carcinoma: a meta-analysis and a systematic review. Drug Des Devel Ther 2016; 10:1345-54. [PMID: 27103788 PMCID: PMC4827914 DOI: 10.2147/dddt.s96766] [Citation(s) in RCA: 6] [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] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Lung cancer is the leading cause of cancer-related mortality in men worldwide. Aberrant RARβ promoter methylation has been frequently investigated in non-small-cell lung carcinoma (NSCLC), the most common form of lung cancer. The aim of present study was to carry out a meta-analysis and a systematic review to evaluate clinicopathological significance of RARβ promoter hypermethylation in NSCLC. A systematic literature search was carried out. The data were extracted and assessed by two reviewers independently. The Cochrane software Review Manager 5.2 was used to conduct the review. Odds ratios (ORs) with 95% corresponding confidence intervals (CIs) were calculated. A total of 18 relevant articles were available for meta-analysis which included 1,871 participants. The frequency of RARβ hypermethylation was significantly increased in NSCLC than in nonmalignant lung tissue, and the pooled OR was 5.69 (P<0.00001). RARβ hypermethylation was significantly more frequently observed in adenocarcinoma (AC) than in squamous cell carcinoma (SCC), and the pooled OR was 1.47 (P=0.005). Hypermethylation of RARβ gene in NSCLC was 2.46 times higher in smoking than in nonsmoking individuals, and the pooled OR was 2.46 (P=0.0002). RARβ hypermethylation rate was not significantly correlated with stage of the disease and sex. RARβ gene methylation status was not associated with prognosis of patients with NSCLC. In conclusion, RARβ promoter hypermethylation significantly increased in NSCLC than in non-neoplastic lung tissue and is predominant in AC, suggesting that RARβ methylation contributes to the development of NSCLC, especially AC. RARβ gene is a potential novel target for development of personalized therapy in patients with NSCLC, and is promising in restoration of retinoic acid-target gene induction via demethylation of RARβ1' promoter.
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Affiliation(s)
- Xiaoyun Song
- Department of Thoracic Surgery, Beijing Chest Hospital, Capital Medical University, Beijing, People’s Republic of China
| | - Kang Shi
- Department of Thoracic Surgery, Beijing Chest Hospital, Capital Medical University, Beijing, People’s Republic of China
| | - Shi-Jie Zhou
- Department of Thoracic Surgery, Beijing Chest Hospital, Capital Medical University, Beijing, People’s Republic of China
| | - Da-Ping Yu
- Department of Thoracic Surgery, Beijing Chest Hospital, Capital Medical University, Beijing, People’s Republic of China
| | - Zhidong Liu
- Department of Thoracic Surgery, Beijing Chest Hospital, Capital Medical University, Beijing, People’s Republic of China
| | - Yi Han
- Department of Thoracic Surgery, Beijing Chest Hospital, Capital Medical University, Beijing, People’s Republic of China
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12
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Atli Eİ, Kalkan R, Özdemir M, Aydın HE, Arslantaş A, Artan S. RARβ gene methylation is a candidate for primary glioblastoma treatment planning. Afr Health Sci 2016; 16:218-26. [PMID: 27358635 DOI: 10.4314/ahs.v16i1.29] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
BACKGROUND We screened RARβ methylation in primary glioblastoma multiforme (GBM) and the results were evaluated based on the clinical data and treatment type. OBJECTIVE The objective of this study was to find new areas for the usage of MS-HRM applications in the determination of methylation levels in primary GBM samples and it shows the association of RARβ methylation with the clinical outcome. METHODS In our study, tumor samples were collected during surgical resection by the Department of Neurosurgery. The clinical and radiologic data was carefully reviewed, compared, and evaluated with the histological results. The methylation status of RARβ was determined by using MS-HRM. RESULTS RARβ gene methylation was detected in 24 out of 40 cases (60%), with different quantitative methylation levels. The mean survival time was 19 months form ethylated cases and 15 months for the non-methylated cases. The survival time of the patients who received treatment was 25 months and the survival time of the patients who received radiotherapy alone or where no treatment protocol applied was 15-20 months. Therefore, a significant difference in survival rates has been observed (P<0.05). This study indicates a potential prognostic value for GBM treatment planning. CONCLUSION Our study is the first study to investigate RARβ methylation in primary GBMs. We conclude that the RARβ gene could be a new prognostic and predictive candidate marker to designate the treatment protocol for primary GBMs.
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13
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Jiang A, Wang X, Shan X, Li Y, Wang P, Jiang P, Feng Q. Curcumin Reactivates Silenced Tumor Suppressor Gene RARβ by Reducing DNA Methylation. Phytother Res 2015; 29:1237-45. [PMID: 25981383 DOI: 10.1002/ptr.5373] [Citation(s) in RCA: 60] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2015] [Revised: 03/28/2015] [Accepted: 04/22/2015] [Indexed: 12/17/2022]
Abstract
Reactivation of tumor suppressor genes by nontoxic bioactive food component represents a promising strategy for cancer chemoprevention. Retinoic acid receptor β (RARβ), one member of the RAR receptor family, is considered as a tumor suppressor. Reduced expression of RARβ has been reported in lung cancer and other solid tumors. DNA hypermethylation of the promoter region of RARβ is a major mechanism for its silencing in tumors. Recently, curcumin has been considered as a potential DNA methyltransferase inhibitor. Herein, we demonstrated that curcumin significantly elevate RARβ expression at the mRNA and protein levels in tested cancer cells. Additionally, curcumin decreased RARβ promoter methylation in lung cancer A549 and H460 cells. Mechanistic study demonstrated that curcumin was able to downregulate the mRNA levels of DNMT3b. In a lung cancer xenograft node mice model, curcumin exhibited protective effect against weight loss because of tumor burden. Tumor growth was strongly repressed by curcumin treatment. As the results from in vitro, RARβ mRNA were increased and DNMT3b mRNA were decreased by curcumin treatment compared with the mice in control group. Altogether, this study reveals a novel molecular mechanism of curcumin as a chemo-preventive agent for lung cancer through reactivation of RARβ.
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Affiliation(s)
- Apei Jiang
- College of Basic Medical Science, Zhejiang Chinese Medical School, Hangzhou, Zhejiang, 310053, China
- Department of Nutrition and Food Hygiene, School of Public Health, Nanjing Medical University, Nanjing, Jiangsu, 211166, China
| | - Xuemin Wang
- Department of Nutrition and Food Hygiene, School of Public Health, Nanjing Medical University, Nanjing, Jiangsu, 211166, China
| | - Xiaoyun Shan
- Department of Nutrition and Food Hygiene, School of Public Health, Nanjing Medical University, Nanjing, Jiangsu, 211166, China
| | - Yuan Li
- Department of Nutrition and Food Hygiene, School of Public Health, Nanjing Medical University, Nanjing, Jiangsu, 211166, China
| | - Pengqi Wang
- Department of Nutrition and Food Hygiene, School of Public Health, Nanjing Medical University, Nanjing, Jiangsu, 211166, China
| | - Pan Jiang
- Department of Nutrition and Food Hygiene, School of Public Health, Nanjing Medical University, Nanjing, Jiangsu, 211166, China
| | - Qing Feng
- Department of Nutrition and Food Hygiene, School of Public Health, Nanjing Medical University, Nanjing, Jiangsu, 211166, China
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14
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Koszinowski S, Boerries M, Busch H, Krieglstein K. RARβ regulates neuronal cell death and differentiation in the avian ciliary ganglion. Dev Neurobiol 2015; 75:1204-18. [PMID: 25663354 PMCID: PMC4832352 DOI: 10.1002/dneu.22278] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [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: 11/06/2014] [Revised: 02/03/2015] [Accepted: 02/03/2015] [Indexed: 02/06/2023]
Abstract
Programmed cell death during chicken ciliary ganglion (CG) development is mostly discussed as an extrinsically regulated process, guided either by the establishment of a functional balance between preganglionic and postganglionic activity or the availability of target‐derived neurotrophic factors. We found that the expression of the gene coding for the nuclear retinoic acid receptor β (RARB) is transiently upregulated prior to and during the execution phase of cell death in the CG. Using retroviral vectors, the expression of RARB was knocked down during embryonic development in ovo. The knockdown led to a significant increase in CG neuron number after the cell death phase. BrdU injections and active caspase‐3 staining revealed that this increase in neuron number was due to an inhibition of apoptosis during the normal cell death phase. Furthermore, apoptotic neuron numbers were significantly increased at a stage when cell death is normally completed. While the cholinergic phenotype of the neurons remained unchanged after RARB knockdown, the expression of the proneural gene Cash1 was increased, but somatostatin‐like immunoreactivity, a hallmark of the mature choroid neuron population, was decreased. Taken together, these results point toward a delay in neuronal differentiation as well as cell death. The availability of nuclear retinoic acid receptor β (RARβ) and RARβ‐induced transcription of genes could therefore be a new intrinsic cue for the maturation of CG neurons and their predisposition to undergo cell death. © 2015 Wiley Periodicals, Inc. Develop Neurobiol 75: 1204–1218, 2015
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Affiliation(s)
- Sophie Koszinowski
- Department of Molecular Embryology, Institute of Anatomy and Cell Biology, Albert-Ludwigs-University Freiburg (ALU), Freiburg, Germany.,University of Freiburg, Faculty of Biology, Schaenzlestrasse 1, D-79104, Freiburg, Germany
| | - Melanie Boerries
- Institute of Molecular Medicine and Cell Research, Centre for Biochemistry und Molecular Cell Research (ZBMZ), University of Freiburg, ALU, Stefan-Meier-Str.17, Freiburg, Germany.,German Cancer Consortium (DKTK), Freiburg, Germany.,German Cancer Research Center (DKFZ), Heidelberg, Germany
| | - Hauke Busch
- Institute of Molecular Medicine and Cell Research, Centre for Biochemistry und Molecular Cell Research (ZBMZ), University of Freiburg, ALU, Stefan-Meier-Str.17, Freiburg, Germany.,German Cancer Consortium (DKTK), Freiburg, Germany.,German Cancer Research Center (DKFZ), Heidelberg, Germany
| | - Kerstin Krieglstein
- Department of Molecular Embryology, Institute of Anatomy and Cell Biology, Albert-Ludwigs-University Freiburg (ALU), Freiburg, Germany
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15
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Chu JH, Gao ZH, Qu XJ. Down-regulation of sphingosine kinase 2 (SphK2) increases the effects of all-trans-retinoic acid (ATRA) on colon cancer cells. Biomed Pharmacother 2014; 68:1089-97. [PMID: 25455157 DOI: 10.1016/j.biopha.2014.10.001] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2014] [Accepted: 10/01/2014] [Indexed: 02/07/2023] Open
Abstract
Sphingosine kinase 2 (SphK2) is a type of sphingosine kinase, which express highly in most of cancers. SphK2 produce sphingosine-1-phosphate (S1P) and then accumulate in cancer cells. Our previous study showed that S1P antagonized the effects of all-trans-retinoic acid (ATRA) via the receptor-dependent and independent pathway. In this study, we aimed to investigate the roles of SphK2 in affecting ATRA's activity in human colon cancer cells. Cell proliferation was estimated by the clonogenic assay. The distribution of cell cycle was analyzed by flow cytometry assay. The apoptotic cells were determined by Annexin V-FITC/PI staining method. Western blotting assay was performed to analyze the levels of the proteins related to apoptosis and cell cycle. The mRNA levels of SphK2 and RARβ were evaluated by real-time PCR assay. RNA interference assay was performed to evaluate SphK2 activity. S1P antagonized the effect of ATRA on HT-29 cell proliferation, the ATRA-induced RARβ expression, the arrest of cell cycle in G1-phase, and induction of apoptosis. Down-regulation of SphK2 resulted in the reverse actions on the S1P-induced antagonistic effects on ATRA. Western blotting analysis indicated that down-regulation of SphK2 might activate apoptotic proteins, regulation of p53/p21(Waf1/Cip1) and EGFR and PI3K/AKT signaling pathways. In conclusion, down-regulation of SphK2 increased the effects of ATRA on colon cancer cells.
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16
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Flamini MI, Gauna GV, Sottile ML, Nadin BS, Sanchez AM, Vargas-Roig LM. Retinoic acid reduces migration of human breast cancer cells: role of retinoic acid receptor beta. J Cell Mol Med 2014; 18:1113-23. [PMID: 24720764 PMCID: PMC4508151 DOI: 10.1111/jcmm.12256] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [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: 09/06/2013] [Accepted: 01/21/2014] [Indexed: 11/27/2022] Open
Abstract
Breast cancer is the most common malignancy in women and the appearance of distant metastases produces the death in 98% of cases. The retinoic acid receptor β (RARβ) is not expressed in 50% of invasive breast carcinoma compared with normal tissue and it has been associated with lymph node metastasis. Our hypothesis is that RARβ protein participates in the metastatic process. T47D and MCF7 breast cancer cell lines were used to perform viability assay, immunobloting, migration assays, RNA interference and immunofluorescence. Administration of retinoic acid (RA) in breast cancer cells induced RARβ gene expression that was greatest after 72 hrs with a concentration 1 μM. High concentrations of RA increased the expression of RARβ causing an inhibition of the 60% in cell migration and significantly decreased the expression of migration-related proteins [moesin, c-Src and focal adhesion kinase (FAK)]. The treatment with RARα and RARγ agonists did not affect the cell migration. On the contrary, the addition of the selective retinoid RARβ-agonist (BMS453) significantly reduced cell migration comparable to RA inhibition. When RARβ gene silencing was performed, the RA failed to significantly inhibit migration and resulted ineffective to reduce moesin, c-Src and FAK expressions. RARβ is necessary to inhibit migration induced by RA in breast cancer cells modulating the expression of proteins involved in cell migration.
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Affiliation(s)
- Marina Ines Flamini
- Tumor Biology Laboratory, Institute of Medicine and Experimental Biology of Cuyo, National Research Council of Argentina, Mendoza, Argentina
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Pérez RJ, Benoit YD, Gudas LJ. Deletion of retinoic acid receptor β ( RARβ) impairs pancreatic endocrine differentiation. Exp Cell Res 2013; 319:2196-204. [PMID: 23756134 DOI: 10.1016/j.yexcr.2013.05.032] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2013] [Revised: 05/30/2013] [Accepted: 05/31/2013] [Indexed: 12/20/2022]
Abstract
All-trans retinoic acid (RA) signals via binding to retinoic acid receptors (RARs α, β, and γ). RA directly influences expression of Pdx1, a transcription factor essential for pancreatic development and beta-cell (β-cell) maturation. In this study we follow the differentiation of cultured wild-type (WT) vs. RARβ knockout (KO) embryonic stem (ES) cells into pancreatic islet cells. We found that RARβ KO ES cells show greatly reduced expression of some important endocrine markers of differentiated islet cells, such as glucagon, islet amyloid polypeptide (Iapp), and insulin 1 (Ins1) relative to WT. We conclude that RARβ activity is essential for proper differentiation of ES cells to pancreatic endocrine cells.
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Affiliation(s)
- Ronald J Pérez
- Pharmacology Department, Weill Medical College of Cornell University, New York, NY 10065, USA
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Abstract
Following an acute central nervous system (CNS) injury, axonal regeneration and functional recovery are extremely limited. This is due to an extrinsic inhibitory growth environment and the lack of intrinsic growth competence. Retinoic acid (RA) signaling, essential in developmental dorsoventral patterning and specification of spinal motor neurons, has been shown through its receptor, the transcription factor RA receptor β2 (RARβ2), to induce axonal regeneration following spinal cord injury (SCI). Recently, it has been shown that in dorsal root ganglion neurons (DRGs), cAMP levels were greatly increased by lentiviral RARβ2 expression and contributed to neurite outgrowth. Moreover, RARβagonists, in cerebellar granule neurons (CGN) and in the brain in vivo, induced phosphoinositide 3-kinase dependent phosphorylation of AKT that was involved in RARβ-dependent neurite outgrowth. More recently, RA-RARβpathways were shown to directly transcriptionally repress a member of the inhibitory Nogo receptor (NgR) complex, Lingo-1, under an axonal growth inhibitory environment in vitro as well as following spinal injury in vivo. This perspective focuses on these newly discovered molecular mechanisms and future directions in the field.
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Affiliation(s)
- Radhika Puttagunta
- Laboratory for Neuroregeneration and Repair, Center for Neurology, Hertie Institute for Clinical Brain Research, University of Tuebingen Tuebingen, Germany
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