Real-time quantitative polymerase chain reaction (RT-qPCR) was used to detect the expression levels of circ_0005379 and miR-17-5p in OSCC tissues and SCC15 cell lines. Western blot was used to detect the expression levels of acyl-CoA oxidase 1 (ACOX1). The circ_0005379 overexpression vector was transfected into SCC15 cells. Methyl thiazolyl tetrazolium blue staining, flow cytometry, Transwell, and Western blot were used to detect the effects of circ_0005379 overexpression on the proliferation, apoptosis, migration, and invasion of SCC15 cells and the expression of E-cadherin, β-catenin, and Snail proteins. Dual luciferase reporter assay and RNA immunoprecipitation were used to examine the regulation of circ_0005379, miR-17-5p, miR-17-5p, and ACOX1 in SCC15 cells. A nude mouse xenograft model of SCC15 cells stably overexpressing circ_0005379 was established, and the effect of circ_0005379 overexpression on the growth of xenografts in nude mice was observed.

Compared with adjacent cancer tissues, the expression levels of circ_0005379 and ACOX1 proteins in OSCC tissues were decreased (P<0.05), and the expression level of miR-17-5p was increased (P<0.05). Compared with HOK-16A cells, the expression levels of circ_0005379 and ACOX1 proteins in SCC15 cell lines were decreased (P<0.05), and the expression level of miR-17-5p was increased (P<0.05). After overexpressing circ_0005379, the activity and number of migrating and invading SCC15 cells and the expression levels of β-catenin and Snail proteins were decreased (P<0.05); however, the apoptosis rate and expression level of E-cadherin protein were increased (P<0.05). In SCC15 cells, circ_0005379 targeted the negative regulation of miR-17-5p expression, and miR-17-5p targeted the negative regulation of ACOX1 expression. Overexpressing miR-17-5p or silencing ACOX1 could reverse the effects of circ_0005379 overexpression on the proliferation, apoptosis, migration, and invasion of OSCC cell lines. The tumor volume and weight of nude mice overexpressing circ_0005379 were decreased (P<0.05), the expression levels of circ_0005379 and ACOX1 protein in tumor tissues were increased (P<0.05), and the expression level of miR-17-5p was decreased (P<0.05).

circ_0005379 may inhibit the proliferation, migration, and invasion of OSCC cells by downregulating the expression of miR-17-5p and upregulating ACOX1, which promote apoptosis and inhibit tumor growth in vivo. circ_0005379 may be a potential target for OSCC treatment.