Novel Hsp90 Inhibitor C086 Potently Inhibits Non-Small Cell Lung Cancer Cells As A Single Agent Or In Combination With Gefitinib

Heat shock proteins as hallmarks of cancer: insights from molecular mechanisms to therapeutic strategies

Heat shock proteins are essential molecular chaperones that play crucial roles in stabilizing protein structures, facilitating the repair or degradation of damaged proteins, and maintaining proteostasis and cellular functions. Extensive research has demonstrated that heat shock proteins are highly expressed in cancers and closely associated with tumorigenesis and progression. The "Hallmarks of Cancer" are the core features of cancer biology that collectively define a series of functional characteristics acquired by cells as they transition from a normal state to a state of tumor growth, including sustained proliferative signaling, evasion of growth suppressors, resistance to cell death, enabled replicative immortality, the induction of angiogenesis, and the activation of invasion and metastasis. The pivotal roles of heat shock proteins in modulating the hallmarks of cancer through the activation or inhibition of various signaling pathways has been well documented. Therefore, this review provides an overview of the roles of heat shock proteins in vital biological processes from the perspective of the hallmarks of cancer and summarizes the small-molecule inhibitors that target heat shock proteins to regulate various cancer hallmarks. Moreover, we further discuss combination therapy strategies involving heat shock proteins and promising dual-target inhibitors to highlight the potential of targeting heat shock proteins for cancer treatment. In summary, this review highlights how targeting heat shock proteins could regulate the hallmarks of cancer, which will provide valuable information to better elucidate and understand the roles of heat shock proteins in oncology and the mechanisms of cancer occurrence and development and aid in the development of more efficacious and less toxic novel anticancer agents.

HSP90: A promising target for NSCLC treatments

The emergence of targeted therapies and immunotherapies has improved the overall survival of patients with nonsmall cell lung cancer (NSCLC), but the 5-year survival rate remains low. New drugs are needed to overcome this dilemma. Moreover, the significant correlation between various client proteins of heat-shock protein (HSP) 90 and tumor occurrence, progression, and drug resistance suggests that HSP90 is a potential therapeutic target for NSCLC. However, the outcomes of clinical trials for HSP90 inhibitors have been disappointing, indicating significant toxicity of these drugs and that further screening of the beneficiary population is required. NSCLC patients with oncogenic-driven gene mutations or those at advanced stages who are resistant to multi-line treatments may benefit from HSP90 inhibitors. Enhancing the therapeutic efficacy and reducing the toxicity of HSP90 inhibitors can be achieved via the optimization of their drug structure, using them in combination therapies with low-dose HSP90 inhibitors and other drugs, and via targeted administration to tumor lesions. Here, we provide a review of the recent research on the role of HSP90 in NSCLC and summarize relevant studies of HSP90 inhibitors in NSCLC.

Small-molecule dual inhibitors targeting heat shock protein 90 for cancer targeted therapy

Heat shock protein 90, also known as Hsp90, is an extensively preserved molecular chaperone that performs a critical function in organizing various biological pathways and cellular operations. As a potential drug target, Hsp90 is closely linked to cancer. Hsp90 inhibitors are a class of drugs that have been extensively studied in preclinical models and have shown promise in a variety of diseases, especially cancer. However, Hsp90 inhibitors have encountered several challenges in clinical development, such as low efficacy, toxicity, or drug resistance, few Hsp90 small molecule inhibitors have been approved worldwide. Nonetheless, combining Hsp90 inhibitors with other tumor inhibitors, such as HDAC inhibitors, tubulin inhibitors, and Topo II inhibitors, has been shown to have synergistic antitumor effects. Consequently, the development of Hsp90 dual-target inhibitors is an effective strategy in cancer treatment, as it enhances potency while reducing drug resistance. This article provides an overview of Hsp90's domain structure and biological functions, as well as a discussion of the design, discovery, and structure-activity relationships of Hsp90 dual inhibitors, aiming to provide insights into clinical drug research from a medicinal chemistry perspective and discover novel Hsp90 dual inhibitors.

Glucuronic acid metabolites of phenolic acids target AKT-PH domain to improve glucose metabolism

Objective

Phenolic acids widely exist in the human diet and exert beneficial effects such as improving glucose metabolism. It is not clear whether phenolic acids or their metabolites play a major role in vivo. In this study, caffeic acid (CA) and ferulic acid (FA), the two most ingested phenolic acids, and their glucuronic acid metabolites, caffeic-4'-O-glucuronide (CA4G) and ferulic-4'-O-glucuronide (FA4G), were investigated.

Methods

Three insulin resistance models in vitro were established by using TNF-α, insulin and palmitic acid (PA) in HepG2 cells, respectively. We compared the effects of FA, FA4G, CA and CA4G on glucose metabolism in these models by measuring the glucose consumption levels. The potential targets and related pathways were predicted by network pharmacology. Fluorescence quenching measurement was used to analyze the binding between the compounds and the predicted target. To investigate the binding mode, molecular docking was performed. Then, we performed membrane recruitment assays of the AKT pleckstrin homology (PH) domain with the help of the PH-GFP plasmid. AKT enzymatic activity was determined to compare the effects between the metabolites with their parent compounds. Finally, the downstream signaling pathway of AKT was investigated by Western blot analysis.

Results

The results showed that CA4G and FA4G were more potent than their parent compounds in increasing glucose consumption. AKT was predicted to be the key target of CA4G and FA4G by network pharmacology analysis. The fluorescence quenching test confirmed the more potent binding to AKT of the two metabolites compared to their parent compounds. The molecular docking results indicated that the carbonyl group in the glucuronic acid structure of CA4G and FA4G might bind to the PH domain of AKT at the key Arg-25 site. CA4G and FA4G inhibited the translocation of the AKT PH domain to the membrane, while increasing the activity of AKT. Western blot analysis demonstrated that the metabolites could increase the phosphorylation of AKT and downstream glycogen synthase kinase 3β in the AKT signaling pathway to increase glucose consumption.

Conclusion

In conclusion, our results suggested that the metabolites of phenolic acids, which contain glucuronic acid, are the key active substances and that they activate AKT by targeting the PH domain, thus improving glucose metabolism.

Heat shock protein 90 inhibitor 17-AAG down-regulates thymidine phosphorylase expression and potentiates the cytotoxic effect of tamoxifen and erlotinib in human lung squamous carcinoma cells

Elevated thymidine phosphorylase (TP) levels, a key enzyme in the pyrimidine nucleoside salvage pathway, in cancer cells, are related to a poor prognosis in a variety of cancers. Heat shock protein 90 (Hsp90) is a ubiquitous molecular chaperone that is involved in the stabilization and maturation of many oncogenic proteins. The aim of this study is to elucidate whether Hsp90 inhibitor 17-AAG could enhance tamoxifen- and erlotinib-induced cytotoxicity in nonsmall cell lung cancer (NSCLC) cells via modulating TP expression in two squamous NSCLC cell lines, H520 and H1703. We found that 17-AAG reduced TP expression via inactivating the MKK1/2-ERK1/2-mitogen-activated protein kinase (MAPK) pathway. TP knockdown with siRNA or ERK1/2 MAPK inactivation with the pharmacological inhibitor U0126 could enhance the cytotoxic and growth inhibitory effects of 17-AAG. In contrast, MKK1-CA or MKK2-CA (a constitutively active form of MKK1/2) vector-enforced expression could reduce the cytotoxic and cell growth inhibitory effects of 17-AAG. Furthermore, 17-AAG enhanced the cytotoxic and cell growth inhibitory effects of tamoxifen and erlotinib in NSCLC cells, which were associated with TP expression downregulation and MKK1/2-ERK1/2 signal inactivation. Taken together, Hsp90 inhibition downregulates TP, enhancing the tamoxifen- and erlotinib-induced cytotoxicity in H520 and H1703 cells.

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.

DRP1 promotes lactate utilization in KRAS-mutant non-small-cell lung cancer cells

Metabolic alterations are well documented in various cancers. Non‐small‐cell lung cancers (NSCLCs) preferentially use lactate as the primary carbon source, but the underlying mechanisms are not well understood. We developed a lactate‐dependent cell proliferation assay and found that dynamin‐related protein (DRP1), which is highly expressed in KRAS‐mutant NSCLC, is required for tumor cells to proliferate and uses lactate as fuel, demonstrating the critical role of DRP1 in the metabolic reprogramming of NSCLC. Metabolic and transcriptional profiling suggests that DRP1 orchestrates a supportive metabolic network to promote lactate utilization and redox homeostasis in lung cancer cells. DRP1 suppresses the production of reactive oxygen species (ROS) and protects cells against oxidative damage by enhancing lactate utilization. Moreover, targeting DRP1 not only reduces HSP90 expression but also enhances ROS‐induced HSP90 cleavage, thus inhibiting activation of mitogen activated protein kinase and PI3K pathways and leading to suppressed lactate utilization and increased ROS‐induced cell death. Taken together, these results suggest that DRP1 is a crucial regulator of lactate metabolism and redox homeostasis in KRAS‐mutant lung cancer, and that targeting lactate utilization by modulating DRP1 activity might be an effective treatment for lung cancer.

Enhanced anti-hepatoma effect of a novel curcumin analog C086 via solid dispersion technology

The novel curcumin analog C086, previously identified as an oral novel heat shock protein 90 (Hsp90) inhibitor, was found to exhibit anti-hepatoma activity in vitro and in vivo. However, owing to its limited aqueous solubility, the usage of C086 in the clinical application was restricted. This research focused on the increase of the aqueous solubility and bioavailability of C086 via a solid dispersion preparation to improve its accumulation in the liver, which accordingly enhanced anti-hepatoma activity. C086-solid dispersion (C086-SD) was successfully prepared by using solvent evaporation technology. As compared with bulk compound, aqueous solubility obtained with the optimal formulation (C086/PVP k30:1/6 (w/w)) was increased by 1.741 million-fold, and in the following oral administration experiment, bioavailability was found to be improved by an approximately 28-fold relative to C086-Suspension and accumulate preferably in the liver. Accordingly, C086-SD exhibited stronger potent anti-proliferative effects against liver cancer cell line (i.e. HepG2) than pure C086. Moreover, C086-SD was found to have an enhanced anti-hepatoma effect using the orthotopic hepatocellular carcinoma xenograft in BALB/C nude mice. The results above suggested the potential application of C086-SD in the treatment of liver cancer.

HSP90 and Co-chaperones: Impact on Tumor Progression and Prospects for Molecular-Targeted Cancer Therapy

Heat shock protein 90 (HSP90), a highly and unique chaperone, presents as a double-edged sword. It plays an essential role in many physiological and pathological processes, including tumor development. The current review highlights a recent understanding of the roles of HSP90 in molecular mechanisms underlying cancer survival and progression. HSP90 and its client proteins through the regulation of oncoproteins including signaling proteins, receptors, and transcriptional factors involved in tumorigenesis. It also has potential clinical application as diagnostic and prognostic biomarkers for assessing cancer progression. In this way, using HSP90 to develop new anticancer therapeutic agents including HSP90 inhibitors, anti-HSP90 antibody, and HSP90-based vaccines has been promising.