MicroRNAs and cancer

MicroRNAs (miRNAs) belong to a class of noncoding, regulatory RNAs that are involved in oncogenesis and show remarkable tissue specificity. miRNAs are approximately 22 nt non-coding RNAs, which regulate gene expression in a sequence-specific manner via translational inhibition or messenger RNA (mRNA) degradation, thus affecting various cellular processes. Since the discovery of their fundamental mechanisms of action, the field of miRNAs has opened a new era in the understanding of small noncoding RNAs. Recent evidence has shown that miRNA controls cell growth, apoptosis, and differentiation. Cancer is a complex genetic disease caused by abnormalities in gene structure and expression, moreover, miRNA expression correlates with cancers and could have a crucial function in tumor progression. Bioinformatic data indicate that each miRNA can control hundreds of target genes, but identification of the accurate miRNA targets will be crucial to exploit the emerging knowledge of miRNA contribution to cancer process.