Augmentation Of Response To Chemotherapy By MiR-506 Through Regulation Of EZH2-β-catenin Signaling Pathway In Serous Ovarian Cancers

Objectives: Chemoresistance is a major challenge in cancer treatment.Ovarian cancer(Ov Ca)remains the most lethal gynecological malignancy and the majority of patients with Ov Ca die from tumor recurrence and chemo-resistance.Tumor drug resistance is associated with a variety of factors,mi RNA may be closely related to drug resistance.mi R-506 is a potent inhibitor of the epithelial-tomesenchymal transition(EMT),which is also associated with chemoresistance.We characterized the role of mi R-506 in chemotherapy response in high-grade serous ovarian cancers.In this study,we discuss whether mi R-506 can increase the sensitivity of cisplatin and PARP inhibitor in serous ovarian cancer cells and its mechanism of drug sensitivity.Methods: This study is divided to 3 parts: 1.Using reporter gene assays,we demonstrated that mi R-506 increased the expression of β-catenin repressors EZH2 by directly targeting the 3’-untranslated region of EZH2.The expression of EZH2 and β-catenin was detected by Western blot in mi R-506 overexpressing ovarian cancer cell lines Hey A8 and SKOV3.And whether mi R-506 was able to down-regulate EZH2 and β-catenin levels.2.Transfection of EZH2 without 3’UTR and mi R-506 or control mi R mimics,and the use of si RNA knockdown EZH2 to observe the changes in EZH2 and β-catenin levels and the sensitivity of cisplatin and PARP inhibitors.3.The expression of β-catenin active vector and the expression of β-catenin inhibitor FH535 were used to observe the changes of drug sensitivity.And to observe overexpression of β-catenin on mi R-506-regulated drug sensitivity.Results: 1.mi R-506 significantly down-regulates the protein levels of EZH2 and β-catenin in the ovarian cancer cell line Hey A8;Search for Target Scan(http://www.targetscan.org/)to obtain a binding site for mi R-506 and EZH2;Compared with the negative control,the mi R-506 mimcs and EZH2 plasmids were found to be significantly different from those of the mutant group in overexpression of mi R-506.Compared with the negativecontrol,the fluorescence of the wild type 3’-UTR reporter vector weakened.(P <0.05).2.The level of β-catenin protein was significantly decreased after Hey A8/SKOV3 cells were down-regulated by EZH2,and the OD value of the ovarian cancer Hey A8 / SKOV3 cells at 450 nm was significantly higher after cisplatin /olaparib.The effect of mi R-506 on the sensitivity of cisplatin and olaparib was partially remedied by overexpression of EZH2 without 3’-UTR.(P <0.05).3.Ovarian cancer Hey A8 / SKOV3 cell line down-regulated β-catenin,the addition of cisplatin/olaparib at 450 nm OD value decreased significantly,the cell clone formation rate was significantly reduced.After the addition of β-catenin,The effect of mi R-506 on the sensitivity of cisplatin and oalaparib was significantly higher than that of the control group(P <0.05).The effect of mi R-506 on the sensitivity of cisplatin and olaparib was partially remedied by overexpression of β-catenin without 3’-UTR.Conclusion: The conclusion drawing from the present study is as fallows: 1.EZH2 is a direct target for mi R-506.2.Mi R-506 can inhibit EZH2-β-catenin signaling pathway.3.Mi R-506 plays a role in drug sensitization by targeting EZH2 to inhibit β-catenin signaling pathway.