The simultaneous miR-155-5p overexpression and miR-223-3p inhibition can activate pEMT in oral squamous cell carcinoma.

Objective: This study aims to explore the effects of miR-223-3p and miR-155-5p on epithelial-mesenchymal transition (EMT) and migration in oral squamous cell carcinoma (OSCC).

Methodology: EMT markers (E-cadherin, N-cadherin, P120 catenin (P120ctn), and vimentin) expression was determined by qRT-PCR and western blot analysis in SCC-9 cells which overexpress miR-155-5p and/or not express miR-223-3p. Scratch assays and Transwell migration assays were conducted to evaluate cell migration ability.

Results: When miR-223-3p was inhibited in OSCC cells, P120ctn and E-cadherin mRNA levels were dramatically downregulated (P<0.05), while N-cadherin levels were significantly upregulated, and the migration ability of OSCC cells increased. The overexpression of miR-155-5p in OSCC cells upregulated miR-223-3p significantly (34-fold) compared to the control group. It also led to significant downregulation of the mRNA of P120ctn and E-cadherin and significant upregulation of the mRNA of N-cadherin and Vimentin (P<0.05). Meanwhile, the migratory ability of OSCC cells significantly increased. When miR-155-5p was overexpressed while miR-223-3p was inhibited, the highest expression of E-cadherin and P120ctn mRNA and the lowest expression of N-cadherin(P<0.05) was observed. Simultaneously, tumor cell migration was significantly facilitated.

Conclusion: miR-223-3p inhibits the migration of OSCC cells, while miR-155-5p can elevate the miR-223-3p mRNA expression. The simultaneous miR-155-5p overexpression and miR-223-3p inhibition can activate pEMT, increasing OSCC migration in vitro. This provides a novel approach and potential target for the effective treatment of OSCC.