Inhibitors of MDM2 and MDMX: a structural perspective

p53 is a potent tumor suppressor with a crucial role in preventing uncontrolled cell proliferation and is therefore frequently deleted or mutated in cancer. For tumors with wild-type p53, its function can be overcome by overactive cellular antagonists, such as the ubiquitin ligase murine double minute clone 2 (MDM2). Restoring p53 activity by inhibiting MDM2 in such cancers can eradicate tumors. Consequently, the MDM2 p53 interaction has been extensively targeted for inhibition by small molecules. In recent years, MDM2-like protein (MDMX), another key downregulator of p53, has gained increasing importance as an additional target for drug development, in order to provide a complementary approach to MDM2 inhibition. In this review, we describe how detailed structural knowledge of the MDM2 p53 interface and, more recently, of the MDMX p53 interaction have helped advance the development of inhibitors against the two targets. We present a summary of the functional biochemistry of MDM2, MDMX and p53 as well as their interactions and examine recent progress in the development of inhibitors of MDM2 and MDMX.