RESUMO
A micro RNA (miRNA) is a single-stranded endogenous, non-coding RNA, with length ranging between 18 and 24 nucleotides and the ability of regulating the expression of other genes on a post-transcriptional level by means of various processes, degradation or repression of target mRNA. miRNAs play a crucial role in regulating fundamental processes such as cell cycle, differentiation and apoptosis; thus, their deregulation can affect normal cell growth and development, and even participate in carcinogenesis. The goals of this paper are: to outline the formation and functions of miRNAs; to determine their role in oral squamous cell carcinoma; to analyze the different miRNAs described and their roles as oncogenes or tumor suppressor genes, depending on their overexpression or subexpression; to describe the different polymorphisms and epigenetic alterations identified; and to determine their role in multidrug resistance.
