MicroRNAs: new actors in the oral cancer scene.

MicroRNAs (miRNAs) are a group of endogenous, non-coding, 18-24 nucleotide length single-strand RNAs that mediate gene expression at the post-transcriptional level through mRNA degradation or translational repression. They are involved in regulating diverse cellular biological processes such as cell cycle, differentiation and apoptosis. Deregulation of miRNAs affects normal biological processes leading to malignancies, including oral squamous cell carcinoma (OSCC). Recent studies have identified aberrant miRNA expression profiles in OSCC tissues and/or cell lines compared with matched normal controls, the mechanisms of which are becoming unveiled. In addition, a small number of dysregulated miRNAs have been implicated either as oncogenes or tumor suppressors, affecting the initiation and progression of OSCC through the regulation of proliferation, apoptosis, metastasis and chemoresistance. Also, these missexpressed miRNAs have been shown to have potential as novel diagnostic, prognostic and therapeutic tools, which are expected to advance the clinical management of OSCC in the near future.