Mdm2 Affects Genome Stability Independent of p53

Mdm2 is a critical negative regulator of the p53 tumor suppressor and is frequently overexpressed in human cancers. However, reports, including our own studies, suggest that Mdm2 has both p53-dependent and p53-independent functions that contribute to genomic instability and transformation when deregulated. We recently elucidated a p53-independent role for Mdm2 in the regulation of the DNA double-strand break repair response, genomic stability, and transformation through interaction with Nbs1, a member of the Mre11/Rad50/Nbs1 DNA double-strand break repair complex. In light of these findings, targeting Mdm2 in human malignancies may have effects other than activating p53. [Cancer Res 2009;69(5):1697-701]