cnf-2024 and Neoplasms

Hsp90 is one of the most important chaperones involved in regulating the maturation of more than 300 client proteins, many of which are closely associated with refractory diseases, including cancer, neurodegenerative diseases, and viral infections. Clinical Hsp90 inhibitors bind to the ATP pocket in the N-terminal domain of Hsp90 and subsequently suppress the ATPase activity of Hsp90. Recently, with the increased understanding of the discrepancies in the isoforms of Hsp90 and the modes of Hsp90-co-chaperone-client complex interactions, some new strategies for Hsp90 inhibition have emerged. Novel Hsp90 inhibitors that offer selective suppression of Hsp90 isoforms or specific disruption of Hsp90-co-chaperone protein-protein interactions are expected to show with satisfactory efficacy and safety profiles. This review summarizes the recent progress in Hsp90 inhibitors. Additionally, Hsp90 inhibitory strategies are emphasized in this review.

Topics: Animals; Antineoplastic Agents; Autoimmune Diseases; Benzoquinones; Forecasting; HSP90 Heat-Shock Proteins; Humans; Immunosuppressive Agents; Lactams, Macrocyclic; Molecular Chaperones; Neoplasms; Protein Binding; Protein Structure, Secondary; Protein Structure, Tertiary

Although Hsp90 inhibitors can inhibit multiple tumorigenic pathways in cancer cells, their anticancer activity has been disappointingly modest. However, by forcing Hsp90 inhibitors into the mitochondria with mitochondrial delivery vehicles, they were converted into potent drugs targeting the mitochondrial Hsp90 paralog TRAP1. Here, to improve mitochondrial drug accumulation without using the mitochondrial delivery vehicle, we increased freely available drug concentrations in the cytoplasm by reducing the binding of the drugs to the abundant cytoplasmic Hsp90. After analyzing X-ray cocrystal structures, the purine ring of the Hsp90 inhibitor 2 (BIIB021) was modified to pyrazolopyrimidine scaffolds. One pyrazolopyrimidine, 12b (DN401), bound better to TRAP1 than to Hsp90, inactivated the mitochondrial TRAP1 in vivo, and it exhibited potent anticancer activity. Therefore, the rationale and feasible guidelines for developing 12b can potentially be exploited to design a potent TRAP1 inhibitor.

Topics: Animals; Antineoplastic Agents; Cell Death; Cell Line, Tumor; Crystallography, X-Ray; HeLa Cells; HSP90 Heat-Shock Proteins; Humans; Mice, Nude; Mitochondria; Molecular Docking Simulation; Neoplasms; Pyrazoles; Pyrimidines