Guardian of genome on the tract: Wild type p53-mdm2 complex inhibition in healing the breast cancer

Small molecules targeting protein-protein interactions for cancer therapy

Protein-protein interactions (PPIs) are fundamental to many biological processes that play an important role in the occurrence and development of a variety of diseases. Targeting the interaction between tumour-related proteins with emerging small molecule drugs has become an attractive approach for treatment of human diseases, especially tumours. Encouragingly, selective PPI-based therapeutic agents have been rapidly advancing over the past decade, providing promising perspectives for novel therapies for patients with cancer. In this review we comprehensively clarify the discovery and development of small molecule modulators of PPIs from multiple aspects, focusing on PPIs in disease, drug design and discovery strategies, structure-activity relationships, inherent dilemmas, and future directions.

Structural studies of antitumor compounds that target the RING domain of MDM2

Mouse double minute 2 homolog (MDM2) is an E3 ubiquitin-protein ligase that is involved in the transfer of ubiquitin to p53 and other protein substrates. The expression of MDM2 is elevated in cancer cells and inhibitors of MDM2 showed potent anticancer activities. Many inhibitors target the p53 binding domain of MDM2. However, inhibitors such as Inulanolide A and MA242 are found to bind the RING domain of MDM2 to block ubiquitin transfer. In this report, crystal structures of MDM2 RING domain in complex with Inulanolide A and MA242 were solved. These inhibitors primarily bind in a hydrophobic site centered at the sidechain of Tyr489 at the C-terminus of MDM2 RING domain. The C-terminus of MDM2 RING domain, especially residue Tyr489, is required for ubiquitin discharge induced by MDM2. The binding of these inhibitors at Tyr489 may interrupt interactions between the MDM2 RING domain and the E2-Ubiquitin complex to inhibit ubiquitin transfer, regardless of what the substrate is. Our results suggest a new mechanism of inhibition of MDM2 E3 activity for a broad spectrum of substrates.