Cancer Management and Research (Jun 2021)
CircPRDM2 Contributes to Doxorubicin Resistance of Osteosarcoma by Elevating EZH2 via Sponging miR-760
Abstract
Jianjun Yuan,* Yan Liu,* Quan Zhang, Zhishuai Ren, Guang Li, Rong Tian Department of Spine Surgery, Tianjin Union Medical Center, Tianjin, 300121, People’s Republic of China*These authors contributed equally to this workCorrespondence: Rong TianDepartment of Spine Surgery, Tianjin Union Medical Center, No. 190, Jieyuan Road, Hongqiao District, Tianjin, 300121, People’s Republic of ChinaTel +86-022-27557253Email [email protected]: Circular RNAs (circRNAs) are implicated in the chemoresistance of human cancers. However, the functions of circRNA PR/SET domain 2 (circPRDM2) in the resistance of osteosarcoma (OS) to doxorubicin (DXR) are unknown.Methods: Quantitative real-time polymerase chain reaction (qRT-PCR) assay was conducted to determine the levels of circPRDM2, microRNA-760 (miR-760) and enhancer of zeste homolog 2 (EZH2). RNase R assay was used to analyze the characteristics of circPRDM2. IC50 of DXR was estimated by Cell Counting Kit-8 (CCK-8) assay. Colony formation assay was performed for cell colony formation ability. Wound-healing assay and transwell assay were utilized for cell migration and invasion. Flow cytometry analysis was conducted for cell apoptosis. Western blot assay was employed for protein levels. Dual-luciferase reporter assay, RNA immunoprecipitation (RIP) assay and RNA pull-down assay were adopted to analyze the relationships among circPRDM2, miR-760 and EZH2. Murine xenograft model assay was utilized to explore DXR resistance in vivo.Results: CircPRDM2 level was enhanced in DXR-resistant OS tissues and cells. CircPRDM2 deficiency inhibited IC50 of DXR, colony formation, migration and invasion and facilitated apoptosis in DXR-resistant OS cells in vitro. CircPRDM2 was identified as the sponge for miR-760. MiR-760 inhibition reversed the inhibitory effects of circPRDM2 knockdown on DXR resistance and cell progression in DXR-resistant OS cells. Moreover, EZH2 was identified as the target gene of miR-760 and EZH2 overexpression abolished miR-760-mediated impacts on DXR sensitivity and malignant behaviors in DXR-resistant OS cells. Also, circPRDM2 silencing improved DXR sensitivity in vivo.Conclusion: Our study demonstrated the role of circPRDM2/miR-760/EZH2 axis in enhancing DXR resistance.Keywords: OS, DXR, circPRDM2, miR-760, EZH2
