Circ_0001742 promotes tongue squamous cell carcinoma progression via miR-431-5p/ATF3 axis.

Circular RNAs (circRNAs) have been demonstrated to involve in the development of various cancers. This study aimed to investigate the functions of circ_0001742 on regulating tongue squamous cell carcinoma (TSCC) development and the underlying mechanisms.The expression of circ_0001742, miR-431-5p and activating transcription factor 3 (ATF3) mRNA was detected by quantitative real-time polymerase chain reaction (qRT-PCR). The protein levels of epithelial-mesenchymal transition (EMT)-related proteins and ATF3 were measured by Western blot analysis. 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2-H-tetrazolium bromide (MTT) and flow cytometry assay were used to evaluate cell proliferation and apoptosis. Besides, Cell migration and invasion were assessed by transwell assay. The relationships between circ_0001742 and miR-431-5p, miR-431-5p and ATF3 were predicted by online software and confirmed by dual-luciferase reporter assay, RNA immunoprecipitation (RIP), and pull-down assay.The expression of circ_0001742 was upregulated in TSCC tissues and cells. Knockdown of circ_0001742 inhibited proliferation, migration, invasion and EMT and induced apoptosis in TSCC cells. Then, miR-431-5p was identified as a target of circ_0001742, and knockdown of miR-431-5p reversed the effects of circ_0001742 knockdown on proliferation, apoptosis, migration, invasion and EMT of TSCC cells. Moreover, miR-431-5p could bind to ATF3, and overexpression of ATF3 rescued the effects mediated by miR-431-5p in TSCC cells. In addition, circ_0001742 regulated ATF3 expression through miR-431-5p.Our results demonstrated that circ_0001742 plays a tumor-promoting effect in TSCC cells by serving as a competing endogenous RNA (ceRNA) to regulate miR-431-5p/ATF3 axis, which might provide a potential therapeutic target for TSCC.