Circular RNA HIPK3 downregulation mediates hydrogen peroxide-induced cytotoxicity in human osteoblasts.

Jinqian Liang,Ying-Chao Shen,Chong Chen,Jianhua Hu,Hong Zhao,Xiang-Yang Zhang

doi:10.18632/aging.102674

Abstract

Hydrogen peroxide (H2O2) induces oxidative injury to human osteoblasts. The expression and potential function of circular RNA HIPK3 (circHIPK3) in H2O2-treated human osteoblasts were tested. We show that H2O2 significantly downregulated circHIPK3 in OB-6 cells and primary human osteoblasts. Furthermore, circHIPK3 levels were decreased in the necrotic femoral head tissues of dexamethasone-treated patients. In OB-6 osteoblastic cells and primary human osteoblasts, forced overexpression of circHIPK3 by a lentiviral construct alleviated H2O2-induced viability reduction, cell death and apoptosis. Contrarily, circHIPK3 silencing by targeted shRNA potentiated H2O2-induced cytotoxicity in OB-6 cells and primary human osteoblasts. Moreover, circHIPK3 downregulation by H2O2 induced miR-124 accumulation in OB-6 cells and primary human osteoblasts. On the contrary, miR-124 inhibition by transfection of the miR-124 inhibitor protected human osteoblasts from H2O2. Importantly, forced overexpression of miR-124 by transfection of the miR-124 mimic induced significant cytotoxicity in OB-6 cells and primary human osteoblasts. H2O2 downregulated miR-124’s targets, cyclin dependent kinase 6 and Rho-Associated Protein Kinase 1, in human osteoblasts. In conclusion circHIPK3 downregulation mediates H2O2-induced cytotoxicity in human osteoblasts.

Highlights

In the pathogenesis of osteoporosis and osteonecrosis, increased reactive oxygen species (ROS) production and oxidative injury will lead to severe damage to human osteoblasts and bone cells [1,2,3,4]
The differentiated, osteoblast-like human OB-6 cells [15,16,17] were treated with hydrogen peroxide (H2O2). Quantitative real-time polymerase chain reaction assay (qPCR) testing circHIPK3 expression confirmed that H2O2 dose-dependently downregulated circHIPK3 in OB-6 osteoblastic cells (Figure 1A)
CircHIPK3 expression levels were decreased in the necrotic femoral head tissues of dexamethasone-treated patients (Figure 1D)

Summary

Introduction

In the pathogenesis of osteoporosis and osteonecrosis, increased reactive oxygen species (ROS) production and oxidative injury will lead to severe damage to human osteoblasts and bone cells [1,2,3,4]. To the cultured human osteoblasts or osteoblastic cells hydrogen peroxide (H2O2) was added, as an in vitro cellular model of osteoporosis/osteonecrosis [5,6,7,8]. H2O2 induces profound oxidative stress, protein damage, lipid peroxidation and DNA breaks in human osteoblasts, leading to cell death and apoptosis. Further understanding the pathological mechanisms of H2O2-induced osteoblast injury is important for the development of possible intervention strategies [5,6,7,8]. The potential functions of circRNAs in the pathogenesis of osteoporosis and osteonecrosis have not been extensively studied

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Conclusion