Regulatory Functions of MicroRNAs in Cancer Pathogenesis

MicroRNAs (miRNAs) are a large family of evolutionary conserved small noncoding RNA molecules that firstly discovered in 1993. They regulate gene expression of about 50% of proteincoding genes at the posttranscriptional level. MiRNAs can target numerous messenger RNAs and subsequent misexpression of them can affect many different signaling pathways. They are playing a pivotal role in cancer development by regulation of the genes expression which involved in the proliferation, survival, differentiation, apoptosis or metastasis of the cancer cells. Several treatment approaches such as inhibition of oncomiRs and restoration of tumor suppressor miRNAs have been established in certain types of cancers and some other miRNAbased strategies are in development for cancer prevention and treatment. Nowadays, cancer is the most important target of miRNA therapeutics and the specific mechanisms by which miRNA mediates cancer pathways needs more research and study.