Abstract
Osteosarcoma is a malignant orthopedic tumor that is frequently diagnosed in the pediatric population. Several studies have summarized the functions of circular RNAs (circRNAs) in the progression of osteosarcoma. This study aimed to investigate a novel circRNA, hsa_circ_0020378 (circ_0020378), and elucidate its functions and underlying mechanisms during osteosarcoma progression. The expression levels of circ_0020378, miR-339-3p, and COL1A1 in osteosarcoma cells and tissues were determined using RT-qPCR or Western blotting. CCK8, transwell migration, colony formation, and xenograft experiments were performed to assess the malignancy of osteosarcoma cells. Luciferase and RNA immunoprecipitation (RIP) experiments were employed to validate the interactions of miR-339-3p with circ_0020378 and COL1A1 3'UTR. Osteosarcoma cells and tissues showed significant upregulation of circ_0020378 and COL1A1 and downregulation of miR-339-3p. Silencing circ_0020378 in osteosarcoma cells inhibited their proliferation, colony formation, and migration. The inhibitive influence of circ_0020378 silencing during osteosarcoma tumorigenesis in vitro was verified in vivo. Circ_0020378 sponged miR-339-3p which targeted COL1A1 3'UTR. Circ _0020378 silencing disrupted the tumor-promoting effect of the miR-339-3p inhibitor in osteosarcoma cells. Furthermore, miR-339-3p inhibitor attenuated the suppressive effect of COL1A1 downregulation on malignant osteosarcoma cell phenotypes. Circ_0020378 stimulates osteosarcoma progression by downregulating miR-339-3p/COL1A1 expression. These findings provide a theoretical basis for the discovery of novel osteosarcoma targets.