RESUMEN
MicroRNAs (miRNA), an abundant class of highly conserved small non-coding RNAs, suppress gene expression by binding to the 3' UTR of target mRNAs, which presents an entirely new approach to post-transcriptional regulation of gene expression. MiRNAs have been shown to play key roles in the regulation of diverse biological processes, such as development, inflammation, apoptosis, and tumorigenesis. Several studies have shown the dysregulated miRNAs in various lymphomas including the overexpression of miR-106a and miR-17-92 in T cell lymphoma;upregulated miR-155, miR-221 and miR-21 in diffuse large B-cell iymphoma and follicular cell lymphoma, and these miRNAs associated with subtypes of diffuse large B-cell lymphoma. Overexpression of the miR-17 cluster showed reduced levels of apoptosis, suggesting that the main effect of these miRNAs was to suppress cell death. Although miRNAs can act as both tumour suppressor and oncogenic molecules, the mechanistic explanation for this dysregulation is unclear but maybe linked to the defects in the miRNA biosynthetic machinery. As more evidence accumulates, it is likely that miRNAs will emerge as a new class of epigenetic regulator.