1. Department of Biological Sciences, Faculty of Health Sciences, University of Macau, Macau, PR China.
2. Cancer Center, Faculty of Health Sciences, University of Macau, Macau, PR China.
3. Institute of Translational Medicine, Faculty of Health Sciences, University of Macau, Macau, PR China.
4. Ministry of Education Frontiers Science Center for Precision Oncology, University of Macau, PR China.
5. Institute of Chinese Medical Sciences, University of Macau, Macau, PR China.
6. Current address: Jinming Yu Academician Workstation of Oncology, Affiliated Hospital of Weifang Medical University, Weifang, Shandong, PR China.
7. Current address: State Key Laboratory of Respiratory Disease & National Clinical Research Center for Respiratory Disease, Guangzhou Institute of Respiratory Health, the First Affiliated Hospital of Guangzhou Medical University, Guangzhou Medical University, Guangzhou, PR China.
Platinum drug-based chemotherapy plays a dominant role in OC (ovarian cancer) treatment. The expression of DNA damage repair (DDR) genes is critical in distinguishing drug-sensitive and drug-refractory patients, as well as in the development of drug resistance in long-term treated patients. CtBP is a highly expressed oncogene in OC and was found to repress DDR genes expression in our previous study. In the present study, the formation of CtBP dimers in live cells was studied, and the functional differences between monomeric and oligomeric CtBP were explored by CHIP-seq and RNA-seq. Besides, the dynamics of CtBP dimer formation in response to the metabolic modulation were investigated by the protein fragment complementation (PCA) assays. We show that dimerized CtBP, but not the dimerization-defective mutant, binds to and represses DDR gene expression in OC cells. Treatment of the mice tumors grown from engrafted OC cells by cisplatin disclosed that high-level CtBP expression promotes the CtBP dimerization and increases the therapeutic effect of cisplatin. Moreover, the CtBP dimerization is responsive to the intracellular metabolic status as represented by the free NADH abundance. Metformin was found to increase the dimerization of CtBP and potentiate the therapeutic effect of cisplatin in a CtBP dimerization-dependent manner. Our data suggest that the CtBP dimerization status is a potential biomarker to predict platinum drug sensitivity in patients with ovarian cancer and a target of metformin to improve the therapeutic effect of platinum drugs in OC treatment.
Keywords: Ovarian cancer, Cisplatin, CtBP, Drug resistance, Metformin