Elevated miR-216b Enhances Cisplatin-Induced Apoptosis in Osteosarcoma by Downregulating JMJD2C and Regulating HIF-1α/HES1 Signaling Axis

Abstract

Background: Cisplatin-based chemotherapy is the standard regimen for osteosarcoma (OS). However, chemoresistance to cisplatin commonly contributes to treatment failure and poor prognosis for metastatic OS patients. The study aims to identify whether miR-216b is dysregulated in OS and its relation to OS cell resistance to cisplatin. Methods: Tumor and paracancerous tissues were collected from OS patients to determine expression patterns of miR-216b and JMJD2C. Pearson correlation analysis was used to evaluate the expression between miR-216b and JMJD2C. CCK8 assay and flow cytometry were used to determine cell viability and apoptosis. Targeting relationship of miR-216b and JMJD2C was determined by dual luciferase reporter assay. Co-immunoprecipitation (IP) assay was used to determine binding between JMJD2C and HIF1α. Chromatin IP (ChIP)-qPCR was used to examine the level of HES1 promoter fragment enriched by H3K9me3 antibodies. Results: miR-216b expression was reduced in OS and positively correlated with patient survival. miR-216b overexpression further enhanced cisplatin-induced apoptosis in OS cells. miR-216b targeted and inhibited JMJD2C. JMJD2C bound and enhanced HIF1α to remove the H3K9 methylation modification at the HES1 promoter region, leading to upregulation of HES1. miR-216b overexpression further reduced cisplatin-induced decrease in tumor growth and weight in nude mice. HES1 overexpression weakened all effects of miR-216b in OS cells and in nude mice xenografts. Conclusion: miR-216b further enhances the effects of cisplatin through downregulating JMJD2C and regulating HIF1α/HES1 signaling axis in OS, suggesting that miR-216b may be an adjunct to cisplatin chemotherapy in the treatment of OS. Funding Statement: This study was supported by General Program of National Natural Science Foundation of China (No. 81572632 & No. 8187100734). Declaration of Interests: The author declares no competing interest exists. Ethics Approval Statement: Human tissue collection protocol was approved by Institutional ethics committee. All animal procedures were approved by Institutional Animal Care and Ethics Committee.