Targeting miR-21-3p inhibits proliferation and invasion of ovarian cancer cells.

Perla M Báez-Vega,Fatma Valiyeva,María J Marcos-Martínez,Josean Flores,Pablo E Vivas-Mejía,Joel Encarnación-Rosado,Adriana Roman,Ileabett M Echevarría Vargas

doi:10.18632/oncotarget.9216

Abstract

MicroRNA-21 is overexpressed in most cancers and has been implicated in tumorigenesis. Accumulating evidence supports a central role for the miR-21 guide strand (miR-21-5p) in ovarian cancer initiation, progression, and chemoresistance. However, there is limited information regarding the biological role of the miR-21 passenger strand (miR-21-3p) in ovarian cancer cells. The aim of this study was to investigate the role of miR-21-3p and its target genes in cisplatin-resistant ovarian cancer cells. Expression profiling of miR-21-5p and miR-21-3p was performed in a panel of cancer cells by qPCR. Colony formation and invasion assays were carried out on ovarian and prostate cancer cells transfected with miR-21-5p and miR-21-3p inhibitors. Dual luciferase reporter assays were used to identify the miR-21-3p target genes in ovarian cancer cells. Our results show that miR-21-5p had higher expression levels compared to miR-21-3p on a panel of cancer cells. Moreover, inhibition of miR-21-5p or miR-21-3p resulted in a significant decrease in ovarian and prostate cancer cell proliferation and invasion. Luciferase reporter assays identify RNA Binding Protein with Multiple Splicing (RBPMS), Regulator of Chromosome Condensation and POZ Domain Containing Protein 1 (RCBTB1), and Zinc Finger protein 608 (ZNF608) as miR-21-3p target genes. SiRNA-induced RBPMS silencing reduced the sensitivity of ovarian cancer cells to cisplatin treatment. Immunohistochemical analyses of serous ovarian cancer patient samples suggest a significant decrease of RBMPS levels when compared to normal ovarian epithelium. Taken together, the data generated in this study suggests a functional role for miR-21-3p in ovarian cancer and other solid tumors.

Highlights

MicroRNAs are endogenously expressed small non-coding RNAs that regulate gene expression at the post-transcriptional level [1, 2]
The aim of this study was to investigate the role of miR-21-3p and its target genes in cisplatin-resistant ovarian cancer cells
To determine if miR-21-5p and miR21-3p contribute to cisplatin resistance in A2780CP20 ovarian cancer cells, cell proliferation and invasion assays were performed in cells transfected with miR-21-5p-Inh and miR-21-3p-Inh, followed by cisplatin (5 μM, final concentration) treatment

Summary

Introduction

MicroRNAs (miRNAs) are endogenously expressed small non-coding RNAs (nc-RNA) that regulate gene expression at the post-transcriptional level [1, 2]. Most miRNA genes are transcribed by RNA polymerase II into a 500-3000 bp primiRNAs. Pri-miRNAs are recognized and processed by the DiGeorge Syndrome Critical Region 8 (DGCR8) and Drosha proteins to generate a 70-bp hairpin loop structurecontaining pre-miRNA [1, 4]. Pri-miRNAs are recognized and processed by the DiGeorge Syndrome Critical Region 8 (DGCR8) and Drosha proteins to generate a 70-bp hairpin loop structurecontaining pre-miRNA [1, 4] These pre-miRNAs are exported to the cytoplasm through the exportin-5 pore protein. The duplex is incorporated into the RNA-induced silencing complex [1], where the Argonaute (Ago2) orients the mature strand (guide strand) for interaction with its target mRNAs. The other chain (passenger strand) is degraded [6]. When both strands play functional roles, the least abundant miRNA is denoted with an asterisk [5, 7]

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