miR-196a Overexpression and miR-196a2 Gene Polymorphism Are Prognostic Predictors of Oral Carcinomas

Background. Oral squamous cell carcinoma (OSCC) is prevalent worldwide, and survival in OSCC has not improved significantly in the last few decades. MicroRNAs have an important regulatory role in oral carcinogenesis. This study investigated the prognostic implications of miR-196 expression and the rs11614913 genotype of the miR-196a2 gene in OSCC. Methods. The clinicopathologic implications of miR-196 in OSCC were investigated using expression assays and genotyping, and the functional role of miR-196 in OSCC pathogenesis was investigated using exogenous expression and knockdown. Results. miR-196 was up-regulated in OSCC tissue relative to control mucosa. High expression of miR-196a, but not miR-196b, was associated with tumor recurrence, nodal metastasis, and mortality. Plasma miR-196a levels could be used to distinguish patients from controls with a separating power of 0.75. Multivariate analysis showed that both high miR-196a expression and TT genotype were independent predictors for poor survival in OSCC. The risk of mortality was greatest for patients with high miR-196a level and positive node status. Expression of miR-196 enhanced oncogenesis of OSCC cells, while inhibition of miR-196 expression attenuated such effects. Conclusions. High miR-196a expression in tumor tissue and the presence of the TT variant of miR-196a2 gene indicate worse survival in OSCC.