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Chemotherapy suppresses SHH gene expression via a specific enhancer. J Genet Genomics 2023; 50:27-37. [PMID: 35998878 DOI: 10.1016/j.jgg.2022.08.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2021] [Revised: 08/12/2022] [Accepted: 08/16/2022] [Indexed: 02/06/2023]
Abstract
Sonic hedgehog (SHH) signaling is a key regulator of embryonic development and tissue homeostasis that is involved in gastrointestinal (GI) cancer progression. Regulation of SHH gene expression is a paradigm of long-range enhancer function. Using the classical chemotherapy drug 5-fluorouracil (5FU) as an example, here we show that SHH gene expression is suppressed by chemotherapy. SHH is downstream of immediate early genes (IEGs), including Early growth response 1 (Egr1). A specific 139 kb upstream enhancer is responsible for its down-regulation. Knocking down EGR1 expression or blocking its binding to this enhancer renders SHH unresponsive to chemotherapy. We further demonstrate that down-regulation of SHH expression does not depend on 5FU's impact on nucleotide metabolism or DNA damage; rather, a sustained oxidative stress response mediates this rapid suppression. This enhancer is present in a wide range of tumors and normal tissues, thus providing a target for cancer chemotherapy and its adverse effects on normal tissues. We propose that SHH is a stress-responsive gene downstream of IEGs, and that traditional chemotherapy targets a specific enhancer to suppress its expression.
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Nishimoto A. Effective combinations of anti-cancer and targeted drugs for pancreatic cancer treatment. World J Gastroenterol 2022; 28:3637-3643. [PMID: 36161054 PMCID: PMC9372808 DOI: 10.3748/wjg.v28.i28.3637] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/01/2022] [Revised: 06/06/2022] [Accepted: 06/30/2022] [Indexed: 02/06/2023] Open
Abstract
Pancreatic cancer is highly aggressive and lethal. Due to the lack of effective methods for detecting the disease at an early stage, pancreatic cancer is frequently diagnosed late. Gemcitabine has been the standard chemotherapy drug for patients with pancreatic cancer for over 20 years, but its anti-tumor effect is limited. Therefore, FOLFIRINOX (leucovorin, fluorouracil, irinotecan, oxaliplatin) as well as combination therapies using gemcitabine and conventional agents, such as cisplatin and capecitabine, has also been administered; however, these have not resulted in complete remission. Therefore, there is a need to develop novel and effective therapies for pancreatic cancer. Recently, some studies have reported that combinations of gemcitabine and targeted drugs have had significant anti-tumor effects on pancreatic cancer cells. As gemcitabine induced DNA damage response, the proteins related to DNA damage response can be suitable additional targets for novel gemcitabine-based combination therapy. Furthermore, KRAS/ RAF/MEK/ERK signaling triggered by oncogenic mutated KRAS and autophagy are frequently activated in pancreatic cancer. Therefore, these characteristics of pancreatic cancer are potential targets for developing effective novel therapies.
In this minireview, combinations of gemcitabine and targeted drugs to these characteristics, combinations of targeted drugs, combinations of natural products and anti-cancer agents, including gemcitabine, and combinations among natural products are discussed.
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Affiliation(s)
- Arata Nishimoto
- Division of Basic Pharmaceutical Science, Department of Pharmacy, Faculty of Pharmaceutical Sciences, Sanyo-Onoda City University, Sanyo-Onoda City 756-0884, Yamaguchi, Japan
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Bajagai YS, Steel JC, Radovanovic A, Stanley D. Prolonged continual consumption of oregano herb interferes with the action of steroid hormones and several drugs, and effects signaling across the brain-gut axis. Food Funct 2020; 12:726-738. [PMID: 33349823 DOI: 10.1039/d0fo02988b] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Herbs and spices have been used throughout human history for their medicinal qualities. The advent of cheap and readily available medicines have lessened the need for herbs and spices as traditional medicines, however, they are rapidly regaining popularity with rising interest of the general population in health, natural products and nutrition. The need for alternative medicines with antimicrobial properties, such as herbs and spices, has also come to the forefront in light of the recent bans of antibiotic use in the livestock industry, including the poultry industry. This large scale use presents an opportunity to observe nutrigenomic effects of prolonged use of herbs on a substantial number of birds fed high concentrations of these products throughout the production cycle. In this manuscript, we investigated the transcriptional effect of continual prolonged oregano supplementation on chicken ileum gene expression. Based on ileum transcriptomics, we report that continual supplementation with 2% oregano altered microbiota-gut-brain axis signalling, rearranged cancer susceptibility towards reduced steroid hormone-related cancers and altered expression of genes targeted by many registered drugs, thus likely affecting their efficiency and side effects. Transcriptional toxicology analysis indicated significant activation of Ventricular Septal Defect and Congenital Heart Disease categories. Our results, counter the notion that natural products such as oregano have the potential for little to no side-effects as they are "natural". The nutrigenomic approach of understanding benefits and side effects of the food we eat, can revolutionize disease management and therapy and have special significance in designing the diets for individuals or livestock with known disease predispositions.
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Affiliation(s)
- Yadav S Bajagai
- Central Queensland University, Institute for Future Farming Systems, Rockhampton, Queensland 4702, Australia.
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Oskoueian E, Abdullah N, Noura R, Ebrahimi M, Ahmad S, Shakeri M. Mode of action of Jatropha curcas phorbol esters in bovine kidney cells. BIOCATALYSIS AND AGRICULTURAL BIOTECHNOLOGY 2019. [DOI: 10.1016/j.bcab.2019.01.010] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Natural Products as Adjunctive Treatment for Pancreatic Cancer: Recent Trends and Advancements. BIOMED RESEARCH INTERNATIONAL 2017; 2017:8412508. [PMID: 28232946 PMCID: PMC5292383 DOI: 10.1155/2017/8412508] [Citation(s) in RCA: 51] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Subscribe] [Scholar Register] [Received: 08/03/2016] [Revised: 12/09/2016] [Accepted: 12/27/2016] [Indexed: 12/17/2022]
Abstract
Pancreatic cancer is a type of common malignant tumors with high occurrence in the world. Most patients presented in clinic had pancreatic cancer at advanced stages. Furthermore, chemotherapy or radiotherapy had very limited success in treating pancreatic cancer. Complementary and alternative medicines, such as natural products/herbal medicines, represent exciting adjunctive therapies. In this review, we summarize the recent advances of using natural products/herbal medicines, such as Chinese herbal medicine, in combination with conventional chemotherapeutic agents to treat pancreatic cancer in preclinical and clinical trials.
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Huang H, Cao K, Malik S, Zhang Q, Li D, Chang R, Wang H, Lin W, Van Doren J, Zhang K, Du Z, Zheng X. Combination of 12-O-tetradecanoylphorbol-13-acetate with diethyldithiocarbamate markedly inhibits pancreatic cancer cell growth in 3D culture and in immunodeficient mice. Int J Mol Med 2015; 35:1617-24. [PMID: 25847449 PMCID: PMC4432920 DOI: 10.3892/ijmm.2015.2163] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2014] [Accepted: 03/03/2015] [Indexed: 11/08/2022] Open
Abstract
The aim of the present study was to determine the effects of 12-O-tetradecanoylphorbol-13-acetate (TPA) and diethyldithiocarbamate (DDTC) alone or in combination on human pancreatic cancer cells cultured in vitro and grown as xenograft tumors in nude mice. Pancreatic cancer cells were treated with either DDTC or TPA alone, or in combination and the number of viable cells was then determined by trypan blue ecxlusion assay and the number of apoptotic cells was determined by morphological assessment by staining the cells with propidium idiode and examining them under a fluorescence microscope. Treatment with DDTC or TPA alone inhibited the growth and promoted the apoptosis of pancreatic cancer cells in a concentration-dependent manner. These effects were more prominent following treatment with TPA in combination with DDTC than following treatment with either agent alone in PANC-1 cells in monolayer cultures and in 3 dimensional (3D) cultures. The potent effects of the combination treatment on PANC-1 cells were associated with the inhibition of nuclear factor-κB (NF-κB) activation and the decreased expression of Bcl-2 induced by DDTC, as shown by NF-κB-dependent reporter gene expression assay and western blot analysis. Furthermore, treatment of nude mice with DDTC + TPA strongly inhibited the growth of PANC-1 xenograft tumors. The results of the present study indicate that the administration of TPA and DDTC in combination may be an effective strategy for inhibiting the growth of pancreatic cancer.
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Affiliation(s)
- Huarong Huang
- Allan H. Conney Laboratory for Anticancer Research, Guangdong University of Technology, Guangzhou, Guangdong 510006, P.R. China
| | - Kajia Cao
- Department of Nasopharyngeal Cancer, Sun Yat-sen University Cancer Center, Guangzhou, Guangdong 510060, P.R. China
| | - Saquib Malik
- Department of Chemical Biology, Ernest Mario School of Pharmacy, Rutgers, The State University of New Jersey, Piscataway, NJ 08854, USA
| | - Qiuyan Zhang
- Allan H. Conney Laboratory for Anticancer Research, Guangdong University of Technology, Guangzhou, Guangdong 510006, P.R. China
| | - Dongli Li
- Allan H. Conney Laboratory for Anticancer Research, Guangdong University of Technology, Guangzhou, Guangdong 510006, P.R. China
| | - Richard Chang
- Department of Chemical Biology, Ernest Mario School of Pharmacy, Rutgers, The State University of New Jersey, Piscataway, NJ 08854, USA
| | - Huaqian Wang
- Allan H. Conney Laboratory for Anticancer Research, Guangdong University of Technology, Guangzhou, Guangdong 510006, P.R. China
| | - Weiping Lin
- Allan H. Conney Laboratory for Anticancer Research, Guangdong University of Technology, Guangzhou, Guangdong 510006, P.R. China
| | - Jeremiah Van Doren
- Department of Chemical Biology, Ernest Mario School of Pharmacy, Rutgers, The State University of New Jersey, Piscataway, NJ 08854, USA
| | - Kun Zhang
- Allan H. Conney Laboratory for Anticancer Research, Guangdong University of Technology, Guangzhou, Guangdong 510006, P.R. China
| | - Zhiyun Du
- Allan H. Conney Laboratory for Anticancer Research, Guangdong University of Technology, Guangzhou, Guangdong 510006, P.R. China
| | - Xi Zheng
- Allan H. Conney Laboratory for Anticancer Research, Guangdong University of Technology, Guangzhou, Guangdong 510006, P.R. China
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Zheng X, Cui XX, Gao Z, Verano M, Huang MT, Liu Y, Rabson AB, Conney AH. Effects of 12-O-tetradecanoylphorbol-13-acetate in combination with gemcitabine on Panc-1 pancreatic cancer cells cultured in vitro or Panc-1 tumors grown in immunodeficient mice. Int J Oncol 2012; 41:2269-75. [PMID: 23041978 DOI: 10.3892/ijo.2012.1651] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2012] [Accepted: 08/17/2012] [Indexed: 11/06/2022] Open
Abstract
In the present study, the effects of 12-O-tetra-decanoylphorbol-13-acetate (TPA) alone or in combination with gemcitabine on the growth of Panc-1 pancreatic cancer cells cultured in vitro or grown in NCr immunodeficient nude mice were investigated. Combinations of TPA and gemcitabine synergi-stically inhibited the growth and induced apoptosis in Panc-1 cells. The combination of TPA (0.16 nM) and gemcitabine (0.5 µM) induced a marked increase in phosphorylated c-Jun NH2-terminal kinase (JNK) in the Panc-1 cells. In animal experiments, NCr nude mice with established Panc-1 tumors received daily intraperitoneal (i.p.) injections of TPA (50 ng/g body weight/day) or gemcitabine (0.5 µg/g body weight/day) alone or in combination for 26 days. Treatment with daily i.p. injections of low doses of TPA or gemcitabine alone had a modest inhibitory effect on the growth of the tumors. However, the combination of low doses of TPA and gemcitabine more potently inhibited the growth of Panc-1 tumors than either agent used individually. Treatment with TPA or gemcitabine alone or in combination did not affect the body weight of the animals. Clinical trials with TPA alone or in combination with gemcitabine on patients with pancreatic cancer are warranted in order to confirm our results.
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Affiliation(s)
- Xi Zheng
- Susan Lehman Cullman Laboratory for Cancer Research, Department of Chemical Biology, Ernest Mario School of Pharmacy, Rutgers, The State University of New Jersey, Piscataway, NJ 08854, USA.
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Oskoueian E, Abdullah N, Ahmad S. Phorbol esters from Jatropha meal triggered apoptosis, activated PKC-δ, caspase-3 proteins and down-regulated the proto-oncogenes in MCF-7 and HeLa cancer cell lines. Molecules 2012; 17:10816-30. [PMID: 22964499 PMCID: PMC6268826 DOI: 10.3390/molecules170910816] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2012] [Revised: 08/02/2012] [Accepted: 08/21/2012] [Indexed: 01/31/2023] Open
Abstract
Jatropha meal produced from the kernel of Jatropha curcas Linn. grown in Malaysia contains phorbol esters (PEs). The potential benefits of PEs present in the meal as anticancer agent are still not well understood. Hence, this study was conducted to evaluate the cytotoxic effects and mode of actions of PEs isolated from Jatropha meal against breast (MCF-7) and cervical (HeLa) cancer cell lines. Isolated PEs inhibited cells proliferation in a dose-dependent manner of both MCF-7 and HeLa cell lines with the IC₅₀ of 128.6 ± 2.51 and 133.0 ± 1.96 µg PMA equivalents/mL respectively, while the values for the phorbol 12-myristate 13-acetate (PMA) as positive control were 114.7 ± 1.73 and 119.6 ± 3.73 µg/mL, respectively. Microscopic examination showed significant morphological changes that resemble apoptosis in both cell lines when treated with PEs and PMA at IC₅₀ concentration after 24 h. Flow cytometry analysis and DNA fragmentation results confirmed the apoptosis induction of PEs and PMA in both cell lines. The PEs isolated from Jatropha meal activated the PKC-δ and down-regulated the proto-oncogenes (c-Myc, c-Fos and c-Jun). These changes probably led to the activation of Caspase-3 protein and apoptosis cell death occurred in MCF-7 and HeLa cell lines upon 24 h treatment with PEs and PMA. Phorbol esters of Jatropha meal were found to be promising as an alternative to replace the chemotherapeutic drugs for cancer therapy.
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Affiliation(s)
- Ehsan Oskoueian
- Department of Microbiology, Faculty of Biotechnology and Biomolecular Sciences, Universiti Putra Malaysia, Serdang 43400, Selangor, Malaysia;
- Agriculture Biotechnology Research Institute of Iran (ABRII)-East and North-East Branch, Mashhad 91735, Iran
| | - Norhani Abdullah
- Department of Biochemistry, Faculty of Biotechnology and Biomolecular Sciences, Universiti Putra Malaysia, Serdang 43400, Selangor, Malaysia;
- Institute of Tropical Agriculture, Universiti Putra Malaysia, Serdang 43400, Selangor, Malaysia
| | - Syahida Ahmad
- Department of Biochemistry, Faculty of Biotechnology and Biomolecular Sciences, Universiti Putra Malaysia, Serdang 43400, Selangor, Malaysia;
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Robbins D, Gu X, Shi R, Liu J, Wang F, Ponville J, McCord JM, Zhao Y. The chemopreventive effects of Protandim: modulation of p53 mitochondrial translocation and apoptosis during skin carcinogenesis. PLoS One 2010; 5:e11902. [PMID: 20689586 PMCID: PMC2912769 DOI: 10.1371/journal.pone.0011902] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2010] [Accepted: 07/04/2010] [Indexed: 11/19/2022] Open
Abstract
Protandim, a well defined dietary combination of 5 well-established medicinal plants, is known to induce endogenous antioxidant enzymes, such as manganese superoxide dismutase (MnSOD). Our previous studies have shown through the induction of various antioxidant enzymes, products of oxidative damage can be decreased. In addition, we have shown that tumor multiplicity and incidence can be decreased through the dietary administration of Protandim in the two-stage skin carcinogenesis mouse model. It has been demonstrated that cell proliferation is accommodated by cell death during DMBA/TPA treatment in the two-stage skin carcinogenesis model. Therefore, we investigated the effects of the Protandim diet on apoptosis; and proposed a novel mechanism of chemoprevention utilized by the Protandim dietary combination. Interestingly, Protandim suppressed DMBA/TPA induced cutaneous apoptosis. Recently, more attention has been focused on transcription-independent mechanisms of the tumor suppressor, p53, that mediate apoptosis. It is known that cytoplasmic p53 rapidly translocates to the mitochondria in response to pro-apoptotic stress. Our results showed that Protandim suppressed the mitochondrial translocation of p53 and mitochondrial outer membrane proteins such as Bax. We examined the levels of p53 and MnSOD expression/activity in murine skin JB6 promotion sensitive (P+) and promotion-resistant (P-) epidermal cells. Interestingly, p53 was induced only in P+ cells, not P- cells; whereas MnSOD is highly expressed in P- cells when compared to P+ cells. In addition, wild-type p53 was transfected into JB6 P- cells. We found that the introduction of wild-type p53 promoted transformation in JB6 P- cells. Our results suggest that suppression of p53 and induction of MnSOD may play an important role in the tumor suppressive activity of Protandim.
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Affiliation(s)
- Delira Robbins
- Department of Pharmacology, Toxicology and Neuroscience, Louisiana State University Health Sciences Center, Shreveport, Louisiana, United States of America
| | - Xin Gu
- Department of Pathology, Louisiana State University Health Sciences Center, Shreveport, Louisiana, United States of America
| | - Runhua Shi
- Feist-Weiller Cancer Center, Louisiana State University Health Sciences Center, Shreveport, Louisiana, United States of America
| | - Jianfeng Liu
- Department of Pharmacology, Toxicology and Neuroscience, Louisiana State University Health Sciences Center, Shreveport, Louisiana, United States of America
| | - Fei Wang
- College of Life Science, Jilin University, Changchun, Jilin Province, China
| | - Jacqulyne Ponville
- Department of Chemistry, Nicholls State University, Thibodaux, Louisiana, United States of America
| | - Joe M. McCord
- Department of Medicine, University of Colorado at Denver and Health Sciences Center, Aurora, Colorado, United States of America
| | - Yunfeng Zhao
- Department of Pharmacology, Toxicology and Neuroscience, Louisiana State University Health Sciences Center, Shreveport, Louisiana, United States of America
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Liu J, Gu X, Robbins D, Li G, Shi R, McCord JM, Zhao Y. Protandim, a fundamentally new antioxidant approach in chemoprevention using mouse two-stage skin carcinogenesis as a model. PLoS One 2009; 4:e5284. [PMID: 19384424 PMCID: PMC2668769 DOI: 10.1371/journal.pone.0005284] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2009] [Accepted: 03/20/2009] [Indexed: 01/29/2023] Open
Abstract
Oxidative stress is an important contributor to cancer development. Consistent with that, antioxidant enzymes have been demonstrated to suppress tumorigenesis when being elevated both in vitro and in vivo, making induction of these enzymes a more potent approach for cancer prevention. Protandim, a well-defined combination of widely studied medicinal plants, has been shown to induce superoxide dismutase (SOD) and catalase activities and reduce superoxide generation and lipid peroxidation in healthy human subjects. To investigate whether Protandim can suppress tumor formation by a dietary approach, a two-stage mouse skin carcinogenesis study was performed. At the end of the study, the mice on a Protandim-containing basal diet had similar body weight compared with those on the basal diet, which indicated no overt toxicity by Protandim. After three weeks on the diets, there was a significant increase in the expression levels of SOD and catalase, in addition to the increases in SOD activities. Importantly, at the end of the carcinogenesis study, both skin tumor incidence and multiplicity were reduced in the mice on the Protandim diet by 33% and 57% respectively, compared with those on basal diet. Biochemical and histological studies revealed that the Protandim diet suppressed tumor promoter-induced oxidative stress (evidenced by reduction of protein carbonyl levels), cell proliferation (evidenced by reduction of skin hyperplasia and suppression of PKC/JNK/Jun pathway), and inflammation (evidenced by reduction of ICAM-1/VCAM-1 expression, NF-κB binding activity, and nuclear p65/p50 levels). Overall, induction of antioxidant enzymes by Protandim may serve as a practical and potent approach for cancer prevention.
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Affiliation(s)
- Jianfeng Liu
- Department of Pharmacology, Toxicology & Neuroscience, Louisiana State University Health Sciences Center, Shreveport, Louisiana, United States of America
| | - Xin Gu
- Department of Pathology, Louisiana State University Health Sciences Center, Shreveport, Louisiana, United States of America
| | - Delira Robbins
- Department of Pharmacology, Toxicology & Neuroscience, Louisiana State University Health Sciences Center, Shreveport, Louisiana, United States of America
| | - Guohong Li
- Department of Neurosurgery, Louisiana State University Health Sciences Center, Shreveport, Louisiana, United States of America
| | - Runhua Shi
- Feist-Weiller Cancer Center, Louisiana State University Health Sciences Center, Shreveport, Louisiana, United States of America
| | - Joe M. McCord
- Department of Medicine, University of Colorado Health Sciences Center, Denver, Colorado, United States of America
| | - Yunfeng Zhao
- Department of Pharmacology, Toxicology & Neuroscience, Louisiana State University Health Sciences Center, Shreveport, Louisiana, United States of America
- * E-mail:
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Wu SN, Wang YJ, Lin MW. Potent stimulation of large-conductance Ca2+-activated K+ channels by rottlerin, an inhibitor of protein kinase C-delta, in pituitary tumor (GH3) cells and in cortical neuronal (HCN-1A) cells. J Cell Physiol 2007; 210:655-66. [PMID: 17133362 DOI: 10.1002/jcp.20866] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
The effects of rottlerin, a known inhibitor of protein kinase C-delta activation, on ion currents were investigated in pituitary tumor (GH3) cells. Rottlerin (0.3-100 microM) increased the amplitude of Ca2+-activated K+ current (I K(Ca)) in a concentration-dependent manner with an EC50 value of 1.7 microM. In intracellular perfusion with rottlerin (1 microM) or staurosporine (10 microM), phorbol 12-myristate 13-acetate-induced inhibition of I K(Ca) in these cells was abolished. In cell-attached mode, rottlerin applied on the extracellular side of the membrane caused activation of large-conductance Ca2+-activated K+ (BK(Ca)) channels, and a further application of BAPTA-AM (10 microM) to the bath had no effect on rottlerin-stimulated channel activity. When cells were exposed to rottlerin, the activation curve of these channels was shifted to less positive potential with no change in the slope factor. Rottlerin increased BK(Ca)-channel activity in outside-out patches. Its change in kinetic behavior of BK(Ca) channels is primarily due to an increase in mean open time. With the aid of minimal kinetic scheme, a quantitative description of rottlerin stimulation on BK(Ca) channels in GH3 cells was also provided. Under current-clamp configuration, rottlerin (1 microM) decreased the firing of action potentials. I K(Ca) elicited by simulated action potential waveforms was enhanced by this compound. In human cortical HCN-1A cells, rottlerin (1 microM) could also interact with the BK(Ca) channel to stimulate I K(Ca). Therefore, rottlerin may directly activate BK(Ca) channels in neurons or endocrine cells.
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Affiliation(s)
- Sheng-Nan Wu
- Department of Physiology, National Cheng Kung University Medical College, Tainan, Taiwan.
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Bond JA, Gescher AJ, Verschoyle RD, Lemoine NR, Errington R, Wiltshire M, Smith PJ, Wynford-Thomas D. Cytotoxic action of phorbol esters on human pancreatic cancer cells. Int J Cancer 2007; 121:1445-54. [PMID: 17582609 DOI: 10.1002/ijc.22869] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
We previously showed that phorbol esters are cytotoxic to human thyroid epithelial cells expressing a mutant RAS oncogene. Here we explore the generality of this finding using cells derived from pancreatic cancer, which, like thyroid, shows a high frequency of RAS mutation, but is a much greater cause of cancer mortality. The response to phorbol myristate acetate (PMA) and related agents was assessed on a panel of 9 pancreatic cancer cell lines, using a range of assays for cell growth and death in vitro and in vivo. In most lines, PMA induced non-apoptotic cell death which was, surprisingly, independent of its "classic" target, protein kinase C. With 24 hr exposure, the IC(50) in the most sensitive line (Aspc-1) was <1 ng/ml (1.6 nM), with survival undetectable at concentrations >/=>/=16 nM, and after only 1 hr exposure the IC(50) was still </=</=16 nM. Interestingly, the efficacy of a second phorbol ester, phorbol dibutyrate, was much lower, and the PMA analogue bryostatin-1, which is in clinical trials against other tumour types, was totally inactive. Pre-treatment of Aspc-1 cells with PMA before subcutaneous inoculation into nude mice prevented, or greatly retarded, subsequent xenograft tumour growth. Furthermore, treatment of established tumours with a single peri-tumoral injection of PMA induced extensive cell death and arrested tumour development. Taken together with recent Phase 1 clinical studies, these data suggest that activity against pancreatic cancer will be attainable by systemic administration of PMA, and point to potential novel therapeutic targets for this highly aggressive cancer.
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Affiliation(s)
- Jane A Bond
- Department of Pathology, School of Medicine, Cardiff University, Cardiff CF14 4XN, United Kingdom
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Salabat MR, Ding XZ, Flesche JB, Ujiki MB, Robin TP, Talamonti MS, Bell RH, Adrian TE. On the mechanisms of 12-O-tetradecanoylphorbol-13-acetate-induced growth arrest in pancreatic cancer cells. Pancreas 2006; 33:148-55. [PMID: 16868480 DOI: 10.1097/01.mpa.0000226896.93945.41] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
OBJECTIVES Protein kinase C (PKC) is involved in cell growth, differentiation, and apoptosis. We investigated the effects of the PKC activator, the tetradecanylphorbol acetate (TPA), in human pancreatic cancer cells. METHODS Cell proliferation was measured by thymidine incorporation. Expression of cell cycle proteins was investigated by Western blot. Real-time reverse transcriptase-polymerase chain reaction was used to measure p21 messenger RNA expression, whereas knockdown of its expression was accomplished with a specific small interferring RNA. Cell cycle phases were determined by flow cytometry. RESULTS TPA time and concentration dependently inhibited thymidine incorporation in Panc-1 and CD18 cells and induced G2/M cell cycle arrest. The TPA decreased cyclin A and B expression, increased cyclin E, and markedly increased the expression of p21 at both the messenger RNA and protein levels. TPA-induced p21 expression and growth inhibition were blocked by the PKC inhibitor, bisindoylmaleimide. TPA induced extracellular signal-regulated kinase1/2 phosphorylation, whereas the MEK inhibitor, PD98059, blocked the TPA-induced p21 expression. Small interferring RNA targeted to p21 blocked TPA-induced p21 protein expression but not TPA-induced cell growth arrest. CONCLUSIONS TPA-induced p21 expression is mediated by the MEK/ERK pathway but is not involved in TPA-induced growth inhibition. In contrast, cyclin A and cyclin B are likely involved in TPA-induced G2/M arrest because both proteins are involved in S phase and G2/M transition during cell proliferation.
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Affiliation(s)
- Mohammad R Salabat
- Department of Surgery and Robert H Lurie Cancer Center, Northwestern University, Feinberg School of Medicine, Chicago, IL 60611, USA
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