The Undervalued Avenue to Reinstate Tumor Suppressor Functionality of the p53 Protein Family for Improved Cancer Therapy - Drug Repurposing

Abstract

p53 and p73 are critical tumor suppressors inactivated in human cancers through various mechanisms. Owing to high structural homology, the proteins share many joined functions and recognize the same set of genes involved in apoptosis and cell cycle regulation. p53 is known as the ‘guardian of the genome’ and forms a critical barrier against cancer development and progression. It is mutated in more than 50% of all human cancers and the germline mutations in TP53 predispose to the early onset of multiple tumors in Li-Fraumeni Syndrome (LFS), the inherited cancer predisposition. Despite the ongoing effort, the treatment of cancers harbouring mutant p53 still remains challenging due to late diagnoses and the treatment-related toxicity and marginal benefit upon approval of new therapies. Presently, the efforts focus on activating p53 exclusively, neglecting the potential of the restoration of the p73 protein in tumors. Taken that several small molecules activating wild-type p53 have failed in clinical trials, and mutant p53 reactivating drugs have not been approved yet, there is a pressing need to develop new treatments activating p53 proteins. This review outlines the still despised therapeutic avenue, drug repurposing, which brings hope for the efficient reinstatement of the p53 protein family for improved cancer therapy.