miR-31: a crucial overseer of tumor metastasis and other emerging roles.

MicroRNAs constitute a family of pleiotropically acting short regulatory RNAs. Increasingly, specific microRNAs have been implicated as key modulators of a variety of normal physiologic processes; moreover, the aberrant activity of certain microRNAs has been linked to the pathogenesis of multiple diseases. The microRNA miR-31 has been identified as a crucial overseer of several normal and diseased phenotypes. Here, we describe current knowledge regarding the functions of miR-31, with an emphasis placed upon the role of this microRNA in neoplastic development and tumor metastasis. Additionally, we highlight a number of recent reports concerning the contributions of miR-31 to other pathological states, the role of this microRNA in normal physiology, and the upstream mechanisms by which miR-31 expression levels are regulated. Assessed collectively, existing evidence suggests that miR-31 concomitantly regulates a number of essential signaling pathways in mammalian cells. For these reasons, further elucidation of the biological actions of miR-31 may prove significant for the prognosis and remediation of various pathological states.