p53: from understanding its structure to advances in therapeutic targeting

The tumor suppressor gene TP53 is the most frequently mutated gene in human cancers and has been a popular area of research in the field of oncology. The p53 protein, encoded by the TP53 gene, not only binds to many targeted genes but also regulates apoptosis, autophagy, cell cycle arrest, metabolism, senescence and the tumor immune microenvironment to suppress tumorigenesis. In recent years, an increasing number of new functions of p53 have been discovered, and p53-mediated tumor suppressor functions have been greatly expanded. Mutations in TP53 not only abolish its ability to suppress tumorigenesis but also confer carcinogenic properties to p53-mutant cells. Because of the prevalence of p53 dysfunction in various disease types, p53 has long been considered an attractive target for new anticancer drugs. However, drugs targeting p53 are still under investigation in early clinical trials and have not been approved for clinical use. This finding is consistent with the speculation that p53 is widely regarded as "undruggable." Surprisingly, several novel therapeutic approaches targeting p53, including MDM2/4 antagonists, compounds that target specific p53 mutants or restore the wild-type function of the mutated p53 protein, p53-based genetic therapies and p53-based tumor immunotherapy, have been developed in recent years. Here, we present a review of the structure, inactivation, and roles of p53 in diseases. In addition, this review discusses the efforts to target diseases associated with p53 dysfunction and the challenges encountered in the clinical development of these approaches.