Mouse double minute 2 homolog–Tumor protein p53 protein–protein interaction interface (MDM2–p53 PPI)

The MDM2–p53 protein–protein interaction interface is a critical regulatory node in cellular homeostasis, primarily governing the stability and activity of the tumor suppressor protein p53 (UniProt: P04637). Under normal conditions, the E3 ubiquitin ligase MDM2 (UniProt: Q00987) binds to the N-terminal transactivation domain of p53, promoting its ubiquitination and subsequent degradation by the proteasome. In many human cancers, particularly those retaining wild-type p53, MDM2 is frequently overexpressed or amplified, leading to the constitutive inactivation of p53-mediated tumor suppression (PMID: 32814827). Therapeutic targeting of this interface involves small molecules or peptides designed to occupy the deep hydrophobic pocket on the surface of MDM2, effectively displacing p53. This inhibition results in the stabilization and accumulation of p53, which then triggers downstream signaling pathways for cell cycle arrest, DNA repair, or apoptosis in malignant cells (PMID: 19826434). Clinical development of MDM2 inhibitors focuses on patients with TP53 wild-type tumors, as the presence of p53 mutations often renders these inhibitors ineffective. However, the clinical utility of these agents is often limited by on-target toxicities, most notably thrombocytopenia and neutropenia, due to p53 activation in normal hematopoietic cells.

Other names

MDM2-p53 complexHDM2-p53 interactionMDM2-p53 binding interfacep53-MDM2 axis

Small molecule inhibitors bind to the hydrophobic pocket of MDM2 where p53 normally binds, thereby sterically hindering the interaction. This prevents MDM2-mediated ubiquitination and subsequent proteasomal degradation of p53, leading to the stabilization and accumulation of p53 protein. The restored p53 then acts as a transcription factor to induce genes involved in cell cycle arrest and apoptosis (PMID: 19826434).