CircRNA circSEPT9 Downregulates miR-10a through Methylation to Promote Cell Proliferation in Laryngeal Squamous Cell Carcinoma

The oncogenic functions of circRNA circSEPT9 have been characterized in triple-negative breast cancer. We analyzed its role in laryngeal squamous cell carcinoma (LSCC). Quantitative reverse-transcription PCR (RT-qPCR) was used to analyze the expression of circSEPT9 and miR-10a in paired LSCC and nontumor tissues donated by 50 patients with LSCC. Methylation-specific PCR (MSP) was performed to analyze the role of circSEPT9 in miR-10a RNA gene methylation. circSEPT9 or miR-10a were overexpressed in LSCC cells to explore the interaction between them. The regulatory role of circSEPT9 and miR-10a in cell proliferation was studied with cell counting kit-8 (CCK-8) assay. CircSEPT9 was highly expressed in LSCC, whereas miR-10a was expressed at a lower level in LSCC. CircSEPT9 and miR-10a were closely correlated across LSCC tissue samples. In LSCC cells, circSEPT9 overexpression increased the methylation of the miR-10a gene and decreased the expression of miR-10a. CircSEPT9 overexpression increased LSCC cell proliferation, whereas miR-10a overexpression decreased cell proliferation. Co-transfection experiments showed that circSEPT9 overexpression attenuated the effects of miR-10a overexpression on cell proliferation. We conclude that circSEPT9 may increase miR-10a methylation to increase cell proliferation in LSCC.