Expression of miR-29b in Malignant Tumors

MicroRNAs (miRNAs) are a class of single-stranded small molecule RNA with about 22 nucleotides in length (Bartel, 2009). These short RNA molecules are able to bind to specifics sites typically present in the three prime untranslated region (3’-UTR) of their target genes and mediate either mRNA decay with perfect base pairing or translational blockade with imperfect base pairing (Pillai et al., 2007). So far, there are about 1424 miRNAs in human, 720 in mouse, and 408 in rat which were confirmed by miRBase datebase (Kozomara and Griffiths-Jones, 2011). It is known that hundreds of miRNAs participate in various biological phenomena, such as cell proliferation, development, differentiation and metabolism (Kavitha et al., 2014). As a special one among them, the miR-29b has unexceptionally become a hot topic. The miR-29b contains miR-29b-1 and miR-29b-2. The structure, function, and regulation of miR-29b are in high degree in human, mouse and rat. miR-29b-1 is transcribed into the same primary transcript from a locus at chromosome 7q32 and separated by 652 bases, which coincides with the common fragile site (FRA7H) (Pillai et al., 2007). miR-29b-2 is from the same transcript located in 1q32 separated by 507 bases (Garzon et al., 2009). In this review, the research progress on the miR-29b and its target genes in malignant tumor will be summarized.