Discovery of 2-((4-resorcinolyl)-5-aryl-1,2,3-triazol-1-yl)acetates as potent Hsp90 inhibitors with selectivity over TRAP1

Small molecule inhibitors targeting heat shock protein 90: An updated review

As a molecular chaperone, heat shock protein 90 (HSP90) plays important roles in the folding, stabilization, activation, and degradation of over 500 client proteins, and is extensively involved in cell signaling, proliferation, and survival. Thus, it has emerged as an important target in a variety of diseases, including cancer, neurodegenerative diseases, and viral infections. Therefore, targeted inhibition of HSP90 provides a valuable and promising therapeutic strategy for the treatment of HSP90-related diseases. This review aims to systematically summarize the progress of research on HSP90 inhibitors in the last five years, focusing on their structural features, design strategies, and biological activities. It will refer to the natural products and their derivatives (including novobiocin derivatives, deguelin derivatives, quinone derivatives, and terpenoid derivatives), and to synthetic small molecules (including resorcinol derivatives, pyrazoles derivatives, triazole derivatives, pyrimidine derivatives, benzamide derivatives, benzothiazole derivatives, and benzofuran derivatives). In addition, the major HSP90 small-molecule inhibitors that have moved into clinical trials to date are also presented here.

Structural aspects of triazole derivatives as HSP90 inhibitors for the treatment of cancer: in silico studies

HSP90, one important class of chaperons has been intensively investigated as a promising and novel class of drug target for cancer therapy from the past few decades. A series of 2-((4-resorcinolyl)-5-aryl-1, 2, 3-triazol-1-yl) acetate derivatives were taken in the present study for the generation of pharmacophore based models, predictive 3 D-QSAR models, docking and ZINC screening studies against HSP90. The investigation included 30 ligands which emerged DHRRR_1 having survival score of 5.59 was found the most effective pharmacophore model. The generated third PLS factor includes a model with significant Q², R², and R² CV values as 0.62, 0.77, and 0.50, respectively. The molecular docking studies against HSP90 showed interactions with important amino acids such as GLY-97, ASN-106, THR-184, ASN-51, PHE-138 and SER-52 required for HSP90 inhibitory activity. According to the docking analysis compound 34 was the top scoring compound, had a docking score of -10.98 from the series and showed interactions with amino acids likeASP-93, GLY-97, AND ASP-102. Using pharmacophore characteristics, the virtual screening investigation was carried out and DHRRR_1 showed the potential ZINC compounds. The ZINC compounds ZINC72417069 and ZINC77522480 showed best XP docking scores (-8.205 and -7.103 consecutively) and the top-scoring compound ZINC72417069 displayed amino acid binding affinity with GLY-97, ASN-106, and THR-184 against HSP90, PDB ID: 2xjx. These ZINC compounds can be used as target for HSP90. The result of the study may further help to the scientist for the design and development of potential HSP90 inhibitors.

Ring-opening of five-membered heterocycles conjugated 4-isopropylresorcinol scaffold-based benzamides as HSP90 inhibitors suppressing tumor growth in vitro and in vivo

A series of ring-opened dihydroxybenzamides have been designed and synthesized as heat shock protein 90 inhibitors. One of derivatives, compound 6b ((N-ethyl-2,4-dihydroxy-5-isopropyl-N-(pyridin-3-yl)benzamide)) demonstrated remarkable antiproliferative activity against in human KRAS mutant A549 and EGFR T790 M mutant H1975 lung cancer cell lines with GI₅₀ values of 0.07 and 0.05 μM, respectively. It is also active against in other cancer cell lines, such as colorectal HCT116 (GI₅₀ = 0.09 μM), liver Hep3B (GI₅₀ = 0.20 μM) and breast MDA-MB-231 (GI₅₀ = 0.09 μM), and shows no evidence of toxicity in normal cell line. Compound 6b has an IC₅₀ of 110.18 nM in HSP90α inhibitory activity, slightly better than reference compound 1 (17-AAG, IC₅₀ = 141.62 nM) and achieves the degradation of multiple HSP90 client proteins in a dose- and time-dependent manner and downstream signaling of Akt in a concentration- and time-dependent manner in the human A549 lung cancer cell line. In the Boyden chamber assay, compound 6b can efficiently inhibit the migration of A549 cells when compared to the reference compound 1. It also induce significant activity through the apoptotic pathway. Treatment with 6b showed no vision toxicity (IC₅₀ > 10 μM) on 661w photoreceptor cells as compared to AUY922 (3a) with a 0.04 μM values of IC₅₀ and has no effect in hERG test. In a bidirectional Caco-2 permeability assay, compound 6b was classified as a highly permeable compound which is not a substrate of efflux transporters. In a pharmacokinetic study in rats, 6b showed an F = 17.8% of oral bioavailability. The effect of metabolic stability of compound 6b in human hepatocytes showed a T_1/2 of 67.59 min. Compound 6b (50 mg/kg, po, daily) exhibits antitumor activity with a 72% TGD (tumor growth delay) in human A549 lung xenograft. The combination of 6b and afatinib, orally administered, showed tumor growth suppression with 67.5% of TGI in lung H1975 xenograft model. Thus compound 6b is a lead compound for further development of potential agents to treat lung cancer.

Heat Shock Proteins and PD-1/PD-L1 as Potential Therapeutic Targets in Myeloproliferative Neoplasms

Simple Summary

Myeloproliferative neoplasms (MPN), which are a heterogeneous group of rare disorders that affect blood cell production in bone marrow, present many significant challenges for clinicians. Though considerable progress has been made, in particular with the JAK1/2 inhibitor ruxolitinib, more effective alternative therapeutic approaches are needed. In the search for new and more efficient therapies, heat shock proteins, also known as stress proteins, and the programmed cell death 1 (PD-1)/programmed death ligand 1 (PD-L1) immune checkpoint axis have been found to be of great interest in hematologic malignancies. Here, we review the therapeutic potential of stress protein inhibitors in the management of patients diagnosed with MPN and summarize the accumulating evidence of the role of the PD-1/PD-L1 axis in MPN in order to provide perspectives on future therapeutic opportunities relative to the inhibition of these targets.

Abstract

Myeloproliferative neoplasms (MPN) are a group of clonal disorders that affect hematopoietic stem/progenitor cells. These disorders are often caused by oncogenic driver mutations associated with persistent Janus kinase (JAK)/signal transducer and activator of transcription (STAT) signaling. While JAK inhibitors, such as ruxolitinib, reduce MPN-related symptoms in myelofibrosis, they do not influence the underlying cause of the disease and are not curative. Due to these limitations, there is a need for alternative therapeutic strategies and targets. Heat shock proteins (HSPs) are cytoprotective stress-response chaperones involved in protein homeostasis and in many critical pathways, including inflammation. Over the last decade, several research teams have unraveled the mechanistic connection between STAT signaling and several HSPs, showing that HSPs are potential therapeutic targets for MPN. These HSPs include HSP70, HSP90 (chaperoning JAK2) and both HSP110 and HSP27, which are key factors modulating STAT3 phosphorylation status. Like the HSPs, the PD-1/PD-L1 signaling pathway has been widely studied in cancer, but the importance of PD-L1-mediated immune escape in MPN was only recently reported. In this review, we summarize the role of HSPs and PD-1/PD-L1 signaling, the modalities of their experimental blockade, and the effect in MPN. Finally, we discuss the potential of these emerging targeted approaches in MPN therapy.