Peptide, Peptidomimetic, and Small-molecule Antagonists of the p53-HDM2 Protein-Protein Interaction.

Modulation of intracellular protein-protein interactions has been - and remains - a challenging goal for the discovery and development of small-molecule therapeutic agents. Progress in the pharmacological targeting and understanding at the molecular level of one such interaction that is relevant to cancer drug research, viz. that between the tumour suppressor protein p53 and its negative regulator HDM2, is reviewed here. The first X-ray crystal structure of a complex between a small peptide from the trans-activation domain of p53 and the N-terminal domain of HDM2 was reported almost 10 years ago. The nature of this interaction, which involves just three residue side chains in the p53 peptide ligand and a compact hydrophobic binding pocket in the HDM2 receptor, together with the attractive concept of reactivating the anti-proliferative functions of p53 in tumour cells, has spurned a great deal of effort aimed at finding drug-like antagonists of this interaction. A variety of approaches, including both structure-guided peptidomimetic and de novo design, as well as high through-put screening campaigns, have provided a wealth of leads that might be turned into actual drugs. There is still some way to go as far as optimisation and preclinical development of such leads is concerned, but it is clear already now that antagonists of the p53-HDM2 protein-protein interaction have a good chance of ultimately being successful in providing a new anti-cancer therapy modality, both in monotherapy and to potentiate the effectiveness of existing chemotherapies.