TSA Suppresses miR-106b-93-25 Cluster Expression through Downregulation of MYC and Inhibits Proliferation and Induces Apoptosis in Human EMC

Zhi-Ning Zhao,Tao Wang,Jiu-Xu Bai,Bo-Quan Jin,Bo Yan,Li-Bo Yao,An-Gang Yang,Qiang Zhou,Wei-Wei Qin,Yan-Ling Meng,Lin-Tao Jia,Moray Campbell

doi:10.1371/journal.pone.0045133

Zhi-Ning Zhao, Tao Wang + Show 10 more

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https://doi.org/10.1371/journal.pone.0045133

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Abstract

Histone deacetylase (HDAC) inhibitors are emerging as a novel class of anti-tumor agents and have manifested the ability to decrease proliferation and increase apoptosis in different cancer cells. A significant number of genes have been identified as potential effectors responsible for the anti-tumor function of HDAC inhibitor. However, the molecular mechanisms of these HDAC inhibitors in this process remain largely undefined. In the current study, we searched for microRNAs (miRs) that were affected by HDAC inhibitor trichostatin (TSA) and investigated their effects in endometrial cancer (EMC) cells. Our data showed that TSA significantly inhibited the growth of EMC cells and induced their apoptosis. Among the miRNAs that altered in the presence of TSA, the miR-106b-93-25 cluster, together with its host gene MCM7, were obviously down-regulated in EMC cells. p21 and BIM, which were identified as target genes of miR-106b-93-25 cluster, increased in TSA treated tumor cells and were responsible for cell cycle arrest and apoptosis. We further identified MYC as a regulator of miR-106b-93-25 cluster and demonstrated its down-regulation in the presence of TSA resulted in the reduction of miR-106b-93-25 cluster and up-regulation of p21 and BIM. More important, we found miR-106b-93-25 cluster was up-regulated in clinical EMC samples in association with the overexpression of MCM7 and MYC and the down-regulation of p21 and BIM. Thus our studies strongly indicated TSA inhibited EMC cell growth and induced cell apoptosis and cell cycle arrest at least partially through the down-regulation of the miR-106b-93-25 cluster and up-regulation of it's target genes p21 and BIM via MYC.

Highlights

Endometrial cancer (EMC) is a common gynecologic malignancy, comprising approximately 20%,30% of all female genital tract malignant tumors
We examined the effects of the histone deacetylase (HDAC) inhibitor TSA on the growth of both ECC-1 and HEC-1A EMC cell lines in vitro
Following treatment with TSA (100 ng/mL) for 24 h, the cells were stained with Annexin V, a phospholipid binding protein that recognizes phosphatidylserine exposed on the cell surface and indicates apoptosis (Fig. 1A)

Summary

Introduction

Endometrial cancer (EMC) is a common gynecologic malignancy, comprising approximately 20%,30% of all female genital tract malignant tumors. The mechanisms of epigenetic control of genes involve DNA methylation and histone modifications without the alteration of the nucleotide sequence of the genes. Such modifications include acetylation, methylation, phosphorylation and ubiquitination of specific amino acid residues of the Ntermini of core histones [3]. Methylation, phosphorylation and ubiquitination of specific amino acid residues of the Ntermini of core histones [3] Among all of these histone modifications, histone acetylation/deacetylation plays a central role in epigenetic regulation of genes [4]. Expression of class I histone deacetylases indicates poor prognosis in endometrial carcinomas, and alterations of HDAC and/or HAT expression are potentially involved in impaired endometrial differentiation [7]

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