miR-218 as a Multifunctional Regulator of Oncogenic Processes in Different Solid Tumors

microRNAs are highly conserved small non-coding regulatory RNAs that involve in post transcriptional regulating of gene expression during different cellular mechanisms. Aberration of miR-218 expression during tumorigenesis of different solid tumors has been reported by numerous studies. In current systematic review article, by using the terms “miR-218” and “cancer” we first searched for English language articles in the PubMed database, published from 1993 to April 2014. Then by a comprehensive review of related articles, we provided some new insights that highlight novel features and functions of miR-218 in initiation and progression of solid tumors. The majority of these studies propose a tumor suppressing role for miR-218 considering the fact that it is significantly down-regulated in tumor tissues compared with normal specimens. Despite accumulating body of evidence regarding tumor suppressor functions of miR-218 in solid tumors; more intensive reviewing about available miR-218 recent original studies and interpretation of existing data, revealed the multifunctional role of miR-218 in these kinds of malignancies by targeting different corresponding target genes. Take all together, MiR-218 targets different cellular processes in cancer cells and its expression pattern is in an important association with various states and features of tumors. It seems that miR-218 can increase the speed of cell cycle and cell division in lower sample grades and along with progression of cancer cells it s function changes to stabilization the cancer cells and not allowing them to invade. thats why it often shows up-regulation in lower grades and down-regulation in metastatic phase. Therefore, it seems of great importance to check samples stage, grade, lymph node metastasis status and other tumor features before evaluation of miR-218 as a prognostic or diagnostic biomarker.