Regulus Therapeutics in collaboration with Duke University suggest that viral miRNAs have a regulatory role in some cancers. They report that a virally derived miRNA mimics the gene-expression control by an endogenous host miRNA that has previously been implicated in human cancer. The collaborators say that they could have possibly found the first oncomir.
The researchers say that the viral miRNA miR-K12-11, which is encoded by the Kaposi's sarcoma associated herpesvirus (KSHV), functions as a mimic of the host cell miRNA known as miR-155. Expression of physiological levels of miR-K12-11 or miR-155 was found to result in the down-regulation of an extensive set of common mRNA and protein targets including genes with known roles in cell growth regulation, according to the team.
Given the known important role of miR-155 in cancer and B-cell function and the association of KSHV infection with B-cell lymphomas and Kaposi's sarcoma, miR-K12-11 may represent the first example of a viral oncomir, report the investigators
The researchers also report that the sequence and functional homology relationship observed between miR-K12-11 and miR-155 is likely not unique, as several other viral miRNAs appear to display this kind of homology to cellular miRNAs.
The research is published in the December 13 issue of Nature.