[MiR-99a inhibits proliferation of oral squamous cell carcinoma by targeting mTOR pathway].

Purpose: To investigate miR-99a expression and its effect on proliferation of oral squamous cell carcinoma (OSCC).

Methods: miRNA microarrays associated with OSCC were identified in GEO database. The expression levels of miR-99a were detected in 63 OSCC tissues and adjacent normal tissues and cell lines. The relationship between clinicopathological parameters and miR-99a expression was analyzed by using ANOVA analysis. The ability of cell growth and clone formation were examined in SCC9 and SCC25 cells transfected with miR-99a mimics. The target genes of miR-99a were predicted by Targetscan software. There resulting data were analyzed using SPSS 19.0 software package.

Results: The differently expressed miRNAs were analyzed based on GSE103931 microarray. miR-99a was significantly downregulated in OSCC tissues and cell lines. miR-99a expression was significantly associated with T stage, pathological grading and patients' prognosis. miR-99a overexpression inhibited OSCC cell proliferation and clone formation, while miR-99a inhibition contributed to decreased proliferation and clone formation ability. In addition, miR-99a combined with mTOR gene's 3'UTR was negatively correlated with mTOR expression in OSCC tissues.

Conclusions: miR-99a functions as a tumor suppressor in OSCC and inhibits OSCC cell proliferation by targeting mTOR.