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Cheng FHC, Lin HY, Hwang TW, Chen YC, Huang RL, Chang CB, Yang W, Lin RI, Lin CW, Chen GCW, Mai SY, Lin JMJ, Chuang YM, Chou JL, Kuo LW, Li C, Cheng ASL, Lai HC, Wu SF, Tsai JC, Chan MWY. E2F6 functions as a competing endogenous RNA, and transcriptional repressor, to promote ovarian cancer stemness. Cancer Sci 2019; 110:1085-1095. [PMID: 30582655 PMCID: PMC6398890 DOI: 10.1111/cas.13920] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [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: 09/27/2018] [Revised: 12/17/2018] [Accepted: 12/19/2018] [Indexed: 12/20/2022] Open
Abstract
Ovarian cancer is the most lethal cancer of the female reproductive system. In that regard, several epidemiological studies suggest that long‐term exposure to estrogen could increase ovarian cancer risk, although its precise role remains controversial. To decipher a mechanism for this, we previously generated a mathematical model of how estrogen‐mediated upregulation of the transcription factor, E2F6, upregulates the ovarian cancer stem/initiating cell marker, c‐Kit, by epigenetic silencing the tumor suppressor miR‐193a, and a competing endogenous (ceRNA) mechanism. In this study, we tested that previous mathematical model, showing that estrogen treatment of immortalized ovarian surface epithelial cells upregulated both E2F6 and c‐KIT, but downregulated miR‐193a. Luciferase assays further confirmed that microRNA‐193a targets both E2F6 and c‐Kit. Interestingly, ChIP‐PCR and bisulphite pyrosequencing showed that E2F6 also epigenetically suppresses miR‐193a, through recruitment of EZH2, and by a complex ceRNA mechanism in ovarian cancer cell lines. Importantly, cell line and animal experiments both confirmed that E2F6 promotes ovarian cancer stemness, whereas E2F6 or EZH2 depletion derepressed miR‐193a, which opposes cancer stemness, by alleviating DNA methylation and repressive chromatin. Finally, 118 ovarian cancer patients with miR‐193a promoter hypermethylation had poorer survival than those without hypermethylation. These results suggest that an estrogen‐mediated E2F6 ceRNA network epigenetically and competitively inhibits microRNA‐193a activity, promoting ovarian cancer stemness and tumorigenesis.
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Affiliation(s)
- Frank H C Cheng
- Department of Biomedical Sciences, National Chung Cheng University, Chia-Yi, Taiwan.,Epigenomics and Human Disease Research Center, National Chung Cheng University, Chia-Yi, Taiwan
| | - Hon-Yi Lin
- Department of Radiation Oncology, Buddhist Dalin Tzu Chi Hospital, Buddhist Tzu Chi Medical Foundation, Chia-Yi, Taiwan.,School of Medicine, Tzu Chi University, Hualien, Taiwan
| | - Tzy-Wei Hwang
- Department of Mathematics, National Chung Cheng University, Chia-Yi, Taiwan
| | - Yin-Chen Chen
- Department of Biomedical Sciences, National Chung Cheng University, Chia-Yi, Taiwan.,Epigenomics and Human Disease Research Center, National Chung Cheng University, Chia-Yi, Taiwan
| | - Rui-Lan Huang
- Department of Obstetrics and Gynecology, School of Medicine, College of Medicine and Shuang Ho Hospital, Taipei Medical University, Taipei, Taiwan
| | - Chia-Bin Chang
- Department of Biomedical Sciences, National Chung Cheng University, Chia-Yi, Taiwan.,Epigenomics and Human Disease Research Center, National Chung Cheng University, Chia-Yi, Taiwan
| | - Weiqin Yang
- School of Biomedical Sciences, The Chinese University of Hong Kong, Hong Kong, China
| | - Ru-Inn Lin
- Department of Radiation Oncology, Buddhist Dalin Tzu Chi Hospital, Buddhist Tzu Chi Medical Foundation, Chia-Yi, Taiwan
| | - Ching-Wen Lin
- Department of Biomedical Sciences, National Chung Cheng University, Chia-Yi, Taiwan.,Epigenomics and Human Disease Research Center, National Chung Cheng University, Chia-Yi, Taiwan
| | - Gary C W Chen
- Department of Biomedical Sciences, National Chung Cheng University, Chia-Yi, Taiwan.,Epigenomics and Human Disease Research Center, National Chung Cheng University, Chia-Yi, Taiwan
| | - Shu-Yuan Mai
- Department of Biomedical Sciences, National Chung Cheng University, Chia-Yi, Taiwan
| | - Jora M J Lin
- Department of Biomedical Sciences, National Chung Cheng University, Chia-Yi, Taiwan.,Epigenomics and Human Disease Research Center, National Chung Cheng University, Chia-Yi, Taiwan
| | - Yu-Ming Chuang
- Department of Biomedical Sciences, National Chung Cheng University, Chia-Yi, Taiwan.,Epigenomics and Human Disease Research Center, National Chung Cheng University, Chia-Yi, Taiwan
| | - Jian-Liang Chou
- Department of Biomedical Sciences, National Chung Cheng University, Chia-Yi, Taiwan.,Epigenomics and Human Disease Research Center, National Chung Cheng University, Chia-Yi, Taiwan
| | - Li-Wei Kuo
- Department of Biomedical Sciences, National Chung Cheng University, Chia-Yi, Taiwan.,Epigenomics and Human Disease Research Center, National Chung Cheng University, Chia-Yi, Taiwan
| | - Chin Li
- Department of Biomedical Sciences, National Chung Cheng University, Chia-Yi, Taiwan
| | - Alfred S L Cheng
- School of Biomedical Sciences, The Chinese University of Hong Kong, Hong Kong, China
| | - Hung-Cheng Lai
- Department of Obstetrics and Gynecology, School of Medicine, College of Medicine and Shuang Ho Hospital, Taipei Medical University, Taipei, Taiwan
| | - Shu-Fen Wu
- Department of Biomedical Sciences, National Chung Cheng University, Chia-Yi, Taiwan.,Epigenomics and Human Disease Research Center, National Chung Cheng University, Chia-Yi, Taiwan
| | - Je-Chiang Tsai
- Department of Mathematics, National Tsing Hua University, Hsin-Chu, Taiwan
| | - Michael W Y Chan
- Department of Biomedical Sciences, National Chung Cheng University, Chia-Yi, Taiwan.,Epigenomics and Human Disease Research Center, National Chung Cheng University, Chia-Yi, Taiwan.,Center for Innovative Research on Aging Society (CIRAS), National Chung Cheng University, Chia-Yi, Taiwan.,Research Center for Environmental Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan
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Cheng FHC, Aguda BD, Tsai JC, Kochańczyk M, Lin JMJ, Chen GCW, Lai HC, Nephew KP, Hwang TW, Chan MWY. A mathematical model of bimodal epigenetic control of miR-193a in ovarian cancer stem cells. PLoS One 2014; 9:e116050. [PMID: 25545504 PMCID: PMC4278842 DOI: 10.1371/journal.pone.0116050] [Citation(s) in RCA: 11] [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] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2014] [Accepted: 11/30/2014] [Indexed: 12/31/2022] Open
Abstract
Accumulating data indicate that cancer stem cells contribute to tumor chemoresistance and their persistence alters clinical outcome. Our previous study has shown that ovarian cancer may be initiated by ovarian cancer initiating cells (OCIC) characterized by surface antigen CD44 and c-KIT (CD117). It has been experimentally demonstrated that a microRNA, namely miR-193a, targets c-KIT mRNA for degradation and could play a crucial role in ovarian cancer development. How miR-193a is regulated is poorly understood and the emerging picture is complex. To unravel this complexity, we propose a mathematical model to explore how estrogen-mediated up-regulation of another target of miR-193a, namely E2F6, can attenuate the function of miR-193a in two ways, one through a competition of E2F6 and c-KIT transcripts for miR-193a, and second by binding of E2F6 protein, in association with a polycomb complex, to the promoter of miR-193a to down-regulate its transcription. Our model predicts that this bimodal control increases the expression of c-KIT and that the second mode of epigenetic regulation is required to generate a switching behavior in c-KIT and E2F6 expressions. Additional analysis of the TCGA ovarian cancer dataset demonstrates that ovarian cancer patients with low expression of EZH2, a polycomb-group family protein, show positive correlation between E2F6 and c-KIT. We conjecture that a simultaneous EZH2 inhibition and anti-estrogen therapy can constitute an effective combined therapeutic strategy against ovarian cancer.
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Affiliation(s)
- Frank H. C. Cheng
- Department of Life Science, National Chung Cheng University, Min-Hsiung, Chia-Yi, Taiwan, Republic of China
- Institute of Molecular Biology, National Chung Cheng University, Min-Hsiung, Chia-Yi, Taiwan, Republic of China
| | | | - Je-Chiang Tsai
- Department of Mathematics, National Chung Cheng University, Min-Hsiung, Chia-Yi, Taiwan, Republic of China
| | - Marek Kochańczyk
- Institute of Fundamental Technological Research, Polish Academy of Sciences, Warsaw, Poland
| | - Jora M. J. Lin
- Department of Life Science, National Chung Cheng University, Min-Hsiung, Chia-Yi, Taiwan, Republic of China
- Institute of Molecular Biology, National Chung Cheng University, Min-Hsiung, Chia-Yi, Taiwan, Republic of China
| | - Gary C. W. Chen
- Department of Life Science, National Chung Cheng University, Min-Hsiung, Chia-Yi, Taiwan, Republic of China
- Institute of Molecular Biology, National Chung Cheng University, Min-Hsiung, Chia-Yi, Taiwan, Republic of China
| | - Hung-Cheng Lai
- Department of Obstetrics and Gynecology, School of Medicine, College of Medicine, Taipei Medical University, Taipei, Taiwan, Republic of China
- Department of Obstetrics and Gynecology, Shuang Ho Hospital, Taipei Medical University, Taipei, Taiwan, Republic of China
- Department of Clinical Pharmacology, Xiangya Hospital, Central South University, Changsha, People's Republic of China
- Institute of Clinical Pharmacology, Central South University, Changsha, People's Republic of China
- Hunan Key Laboratory of Pharmacogenetics, Changsha, People's Republic of China
| | - Kenneth P. Nephew
- Medical Sciences, Department of Cellular and Integrative Physiology, Indiana University School of Medicine, Bloomington, Indiana, United States of America
| | - Tzy-Wei Hwang
- Department of Mathematics, National Chung Cheng University, Min-Hsiung, Chia-Yi, Taiwan, Republic of China
- * E-mail: (MWYC); (TWH)
| | - Michael W. Y. Chan
- Department of Life Science, National Chung Cheng University, Min-Hsiung, Chia-Yi, Taiwan, Republic of China
- Institute of Molecular Biology, National Chung Cheng University, Min-Hsiung, Chia-Yi, Taiwan, Republic of China
- * E-mail: (MWYC); (TWH)
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