Microarray profile of circular RNAs identifies hsa_circRNA_102459 and hsa_circRNA_043621 as important regulators in oral squamous cell carcinoma

Circular RNAs (circRNAs) have emerged as important regulators of carcinogenesis. However, the role of circRNAs in oral squamous cell carcinoma (OSCC) remains limited. Here, total RNAs were extracted from three pairs of OSCC and adjacent normal tissues and subjected to circRNA microarrays to detect the differentially expressed circRNAs. Gene Ontology (GO) and functional category analyses were used to identify circRNAs associated with tumor cell proliferation pathways. Then, gain‑of‑function assays or loss‑of‑function assays were conducted to investigate the functions of the most upregulated and downregulated circRNAs on TSCC1 cell proliferation, cell cycle and apoptosis using CCK‑8 and EdU assays, flow cytometry and Hoechst 33258 staining, respectively. The results revealed that hsa_circRNA_102459 was significantly downregulated and hsa_circRNA_043621 was significantly upregulated in OSCC tissues. Clinical stage, tumor differentiation, lymph node metastasis presented significant difference in regards to the expression of circRNA_043621 and circRNA_102459. The in vitro experiments further demonstrated that upregulation of circRNA_102459 or downregulation of circRNA_043621 significantly suppressed TSCC1 cell proliferation, induced cell cycle G0/G1 phase arrest and promoted apoptosis. Furthermore, the MAPK and PI3K/Akt pathways were suppressed, while Bcl‑2 family members were activated by circRNA_102459 overexpression and circRNA_043621 knockdown. Taken together, our study indicates that differentially expressed circRNAs are closely related to the carcinogenesis of OSCC. Among these, circRNA_102459 and circRNA_043621 may function as a tumor‑suppressor and promoter, respectively, of OSCC carcinogenesis, and thus may be valuable diagnostic biomarkers of OSCC.