Cisplatin-induced epigenetic activation of miR-34a sensitizes bladder cancer cells to chemotherapy

Heng Li,Wei Guan,Hua Xu,Gan Yu,Bin Lang,Zhangqun Ye,Wei Xiao,Xianguo Chen,Haibing Xiao,Xiaolin Guo,Runlin Shi,Ding Xia

doi:10.1186/1476-4598-13-8

Abstract

BackgroundAccumulating evidence suggests a tumor suppressive role for miR-34a in human carcinogenesis. However, its precise biological role remains largely elusive. This study aimed to reveal the association of the miR-34a expression and its modulation of sensitivity to cisplatin in muscle-invasive bladder cancer (MIBC).MethodsmiR-34a expression in MIBC cell lines and patient tissues was investigated using qPCR. The methylation analysis of miR-34a promoter region was performed by MassARRAY. Synthetic short single or double stranded RNA oligonucleotides and lentiviral vector were used to regulate miR-34a expression in MIBC cells to investigate its function in vitro and in vivo.ResultsmiR-34a expression was frequently decreased in MIBC tissues and cell lines through promoter hypermethylation while it was epigenetically increased in MIBC cells following cisplatin treatment. Increased miR-34a expression significantly sensitized MIBC cells to cisplatin and inhibited the tumorigenicity and proliferation of cancer cells in vitro and in vivo. Furthermore, we identified CD44 as being targeted by miR-34a in MIBC cells following cisplatin treatment, and increased CD44 expression could efficiently reverse the effect of miR-34a on MIBC cell proliferation, colongenic potential and chemosensitivity.ConclusionsCisplatin-based chemotherapy induced demethylation of miR-34a promoter and increased miR-34a expression, which in turn sensitized MIBC cells to cisplatin and decreased the tumorigenicity and proliferation of cancer cells that by reducing the production of CD44.

Highlights

Bladder cancer is the ninth most common cancer diagnosis worldwide, with more than 330,000 new cases each year and more than 130,000 deaths per year [1]
Results miR-34a is frequently decreased in human muscle-invasive bladder cancer (MIBC) tissues and cell lines through promoter hypermethylation To investigate the role of miR-34a in MIBC, we firstly evaluated the expression of miR-34a in four MIBC cell lines (5637, HT1376, J82 and T24) and a nontumorigenic bladder cell line SV-HUC-1 by qPCR
To explore whether promoter hypermethylation leads to the suppression of expression, we examined the expression of miR-34a in bladder epithelial cell lines treated with the DNA methylation inhibitor, 5-aza-dC

Summary

Introduction

Bladder cancer is the ninth most common cancer diagnosis worldwide, with more than 330,000 new cases each year and more than 130,000 deaths per year [1]. MiR-34a is the most significantly inducted miRNAs by p53 and ectopic miR-34a expression induces apoptosis, cell-cycle arrest, senescence and alters cancer cell chemosensitivity through direct targeting multiple genes in p53 signaling pathway, such as Sirt-1, CDK6, E2F3 and Bcl-2 [12,13,14]. This mechanism seems not fitting well in cisplatin-based bladder cancer chemotherapy as miR-34a chemosensitizes bladder cancer cells to cisplatin treatment regardless of p53-Rb pathway status [9]. This study aimed to reveal the association of the miR-34a expression and its modulation of sensitivity to cisplatin in muscle-invasive bladder cancer (MIBC)

Objectives

Methods

Results

Conclusion