Objective: Circular RNAs (circRNAs) play a wide role in human cancers, including oral squamous cell carcinoma (OSCC). The purpose of this study was to investigate the biological functions of circ_0001971 and associated mechanisms in OSCC.
Materials and methods: The expression of circ_0001971, miR-194, and miR-204 was detected by quantitative Real Time-Polymerase Chain Reaction (qRT-PCR). Cell proliferation and viability were assessed using cell counting kit-8 (CCK-8) assay. Cell migration and invasion were examined using the transwell assay. Cell apoptosis was monitored by flow cytometry assay. The protein levels of proliferation marker (CyclinD1), epithelial mesenchymal-transition (EMT) markers (E-cadherin (E-cad) and N-cadherin (N-cad)) and apoptosis markers (Cleaved-caspase-3 (Cleaved-cas-3) and Cleaved-caspase-9 (Cleaved-cas-9)) were measured by Western blot. The relationship between circ_0001971 and miR-194 or miR-204 was predicted by online tool starBase and verified by the Dual-Luciferase reporter assay and RNA immunoprecipitation (RIP) assay. Tumor formation assay in nude mice was conducted to observe the role of circ_0001971 in vivo.
Results: The expression of circ_0001971 was significantly increased in tumor tissues and cell lines. Circ_0001971 knockdown inhibited cell proliferation, migration, and invasion but promoted cisplatin (DDP) sensitivity and cell apoptosis. It was confirmed that miR-194 and miR-204 were targets of circ_0001971, and miR-194 inhibition or miR-204 inhibition reversed the effects of circ_0001971 knockdown in OSCC cells. Moreover, circ_0001971 knockdown impeded tumorigenesis and development in vivo.
Conclusions: Circ_0001971 regulates cell proliferation, migration, invasion, apoptosis, and chemosensitivity of OSCC by interacting with miR-194 and miR-204 in vitro and in vivo. We provided a theoretical basis for the action mechanism of circ_0001971 on OSCC progression and chemosensitivity.