Abstract: To investigate the expression of circular RNA (circRNA) circKRT75 in tongue squamous cell carcinoma (TSCC) tissues and the effects of silencing its expression on the proliferation and invasion of TSCC cells. The cBioPortal database was used to analyze the expression of circKRT75 in TSCC tissues and the correlation between circKRT75 expression and survival in TSCC patients. Quantitative real-time polymerase chain reaction (qPCR) was used to detect circKRT75 expression in TSCC cell lines H357, Tca8113, TSCCA, HN13, and SCC-9. si-circKRT75 and control plasmids were transfected into H357 cells using lipofectamine, defining them as the si-circKRT75 and si-NC groups, respectively. The effects of low-expression circKRT75 on the proliferation and invasion of H357 cells were assessed by MTT and Transwell assays, respectively. Western blot analysis was used to examine the effects of low-expression circKRT75 on the expression of Cyclin E and Cyclin-dependent kinase 2 (CDK2), matrix metalloproteinase-2 (MMP-2) and Alpha-smooth muscle actin (α-SMA) in H357 cells. Dual-luciferase reporter assays were used to validate the targeting relationship between circKRT75 and miR-128-3p. The cBioPortal database was used to analyze the correlation between the expression of circKRT75 and miR-128-3p in TSCC tissues. qPCR was used to detect the effect of low-expression circKRT75 on miR-128-3p expression. circKRT75 expression was higher in TSCC tissues than in normal oral mucosa tissues (P<0.01). circKRT75 expression was negatively correlated with TSCC patient survival (P<0.01). Compared with normal human oral keratinocytes (HOK) cells, circKRT75 expression was higher in TSCC cell lines H357, Tca8113, TSCCA, HN13, and SCC-9 (all P<0.05). Compared with the si-NC group, low circKRT75 expression inhibited the proliferation (P<0.05) and invasion (P<0.01) of H357 cells. Low circKRT75 expression downregulated the expression of Cyclin E, CDK2, MMP-2, and α-SMA proteins in H357 cells (all P<0.01). circKRT75 had a targeting relationship with miR-128-3p (P<0.01). The expression of circKRT75 in TSCC tissues was negatively correlated with the expression of miR-128-3p (P<0.01). Compared with the si-NC group, low expression of circKRT75 upregulated miR-128-3p expression (P<0.01). circKRT75 is highly expressed in TSCC tissues and cell lines, and low expression of circKRT75 inhibits the proliferation and invasion of TSCC cells by regulating miR-128-3p expression. circKRT75 may become a molecular therapeutic target for TSCC.
Key words: circular RNA; tongue squamous cell carcinoma; microRNA; cell proliferation; cell migration
（Acta Laser Biology Sinica, 2026, 35(1): 081-087）