BACKGROUND: miR-126 has been reported to be differentially expressed in various malignancies, whereas its role in the pathogenesis of tongue squamous cell carcinoma (TSCC) remains largely unknown.

MATERIAL AND METHODS: In this study, we collected 21 pairs of TSCC cancerous and adjacent non-cancerous tissue samples, with which we performed real-time PCR to determine and compare the expression of 6 candidate miRNAs that are reportedly associated with tumorigenesis of TSCC, including miR-100, miR-451, miR-221, let-7a, miR-21, and miR-126. We further performed luciferase assay to validate KRAS as a target of miR-126, and conducted transfection to study the effect of miR-126 on proliferation and apoptosis of the cells.

RESULTS: We identified that miR-126 was significantly downregulated in the cancerous tissue samples compared with the non-cancerous control tissue samples. By using computational analysis, we identified that KRAS is a virtual target of miR-126, and such association was verified by using luciferase assay. In addition, we found that mRNA and protein expression level of KRAS was significantly higher in the tumor tissue than the control tissue samples.

CONCLUSIONS: The following in vitro experiment showed that both mRNA and protein KRAS expression were significantly decreased in SCC-15 cells in which miR-126 was overexpressed, in comparison with similar cells transfected with a negative control, while downregulation of miR-126 by transfecting the cells with miR-126 inhibitors significantly upregulated the mRNA and protein expression of KRAS. Conclusions: miR-126 might be a promising diagnostic and therapeutic target in the prevention and management of TSCC patients.

Keywords: 3' Untranslated Regions - genetics, Apoptosis - genetics, Base Sequence, Carcinogenesis - pathology, Carcinoma, Squamous Cell - pathology, Cell Survival - genetics, Down-Regulation - genetics, Genes, Reporter, Luciferases - metabolism, Molecular Sequence Data, Proto-Oncogene Proteins p21(ras) - metabolism, RNA, Messenger - metabolism, Real-Time Polymerase Chain Reaction