Downregulation of miR-22 Contributes to Epithelial-Mesenchymal Transition in Osteosarcoma by Targeting Twist1.

Shu-Tao Zhu,Yang Liu,Jun-Yi Wang,Xiao Wang,Guang-Hui Xi

doi:10.3389/fonc.2020.00406

Abstract

The epithelial-mesenchymal transition (EMT) is a vital step in osteosarcoma (OS) progression toward metastasis, but the specific molecular events governing this process are incompletely characterized, with miRNAs having increasingly been found to regulate the EMT. In this study, We assessed levels of miR-22 and its target, Twist1, via real-time PCR (qRT-PCR). We further used functional proliferation assays, measures of cell morphology, and western blotting to assess the functional relevance of miR-22 in OS and confirmed Twist1 as a miR-22 target via luciferase reporter assay. We observed a significant decrease in miR-22 levels in OS tumor samples relative to normal tissue, with such downregulating being significantly associated with tumor histological grade. When overexpressed, miR-22 impaired OS cell proliferation and EMT progression. We found Twist1 to be a direct miR-22 target, with levels of miR-22 and Twist1 mRNA being inversely correlated in patient samples. When overexpressed, miR-22 suppressed Twist1 translation and thereby attenuated the EMT in OS cells. These results clearly demonstrate that miR-22 can regulate the EMT in OS cells via targeting Twist1, thus highlighting a potentially novel pathway that can be therapeutically targeted in order to treat OS.

Highlights

Osteosarcoma (OS) is a highly prevalent form of bone cancer that most frequently impacts adolescents and younger children [1], in whom it is the second most prominent cancer-associated cause of death [2]
We further found that there was a negative correlation between miR-22 expression and tumor histological grade (Figure 1B)
We assessed the effects of miR-22 on OS cell proliferation and metastasis via generating human OS cell lines (HOS and MG63) stably expressing miR-22 or negative control (Figure 2A)

Summary

Introduction

Osteosarcoma (OS) is a highly prevalent form of bone cancer that most frequently impacts adolescents and younger children [1], in whom it is the second most prominent cancer-associated cause of death [2]. The remaining 30% of patients, often exhibit high rates of local tumor recurrence, early development of tumor metastases, and limited tumor chemosensitivity, contributing to the poor outcomes in these individuals [4]. MicroRNAs (miRNAs) are small RNA molecules which lack coding potential, yet which are able to readily mediate the post-translational regulation of target mRNA expression via suppressing translation or inducing degradation [5]. These miRNAs are capable of regulating a broad array of cellular processes, such as differentiation, apoptotic death, or proliferation with specific miRNAs serving to suppress or promote tumor function in a context-dependent manner [6,7,8]

Methods

Results

Conclusion