Circular RNA 0060428 sponges miR-375 to promote osteosarcoma cell proliferation by upregulating the expression of RPBJ.

Osteosarcoma (OS) is the most common primary bone tumor, and mainly occurs in children and early adults. The overall pathogenesis of osteosarcoma remains unclear. Circular RNAs (circRNAs) have been demonstrated to be one of the regulators in tumors as non-coding RNAs. In present study, we identified an elevated expressed circ-0060428 in osteosarcoma cells. The results of CCK-8 and flow cytometry assay showed that circ-0060428 promoted cell proliferation and reduced cell apoptosis of osteosarcoma cells. Bioinformatics analyses predicted the binding site between miR-375 to RPBJ and circ-0060428, and dual luciferase reporter assay verified this prediction. Furthermore, miRNA inhibitor of miR-375 could recover the influence of cell proliferation and apoptosis by knocking down the expression of circ-0060428. Meanwhile, knockdown of both circ-0060428 and RBPJ resulted in a lower apoptosis rate than circ-0060428 alone. Western blot analyses indicated that circ-0060428 regulated the expression of apoptosis related proteins (Bax, Bcl-2, and cleaved-Caspase-3) by upregulating RPBJ expression in osteosarcoma cells. Altogether, we confirmed the up-regulated circ-0060428 could improve the proliferation and survival of osteosarcoma cells by sponging miR-375 to upregulate RBPJ expression. This finding supported a novel clinically biomarker and treatment target for osteosarcoma therapy.