High-level expression of Hsp90β is associated with poor survival in resectable non-small-cell lung cancer patients

GRP94 promotes anoikis resistance and peritoneal metastasis through YAP/TEAD1 pathway in gastric cancer

Anoikis resistance allows cancer cells to avoid death caused by detachment from the extracellular matrix's adhesion, enabling these cells to infiltrate and migrate to regions such as the peritoneum. This study emphasizes GRP94's involvement in anoikis resistance and peritoneal metastasis in gastric cancer (GC). It's found that GRP94 overexpression, linked to poor prognosis, was potentially due to SP1 and GRP94 promoter interactions, confirmed through dual luciferase reporter (DLR), chromatin immunoprecipitation (ChIP), and quantitative real-time PCR (real-time qPCR). Increased GRP94 enhanced GC cells' anoikis resistance and metastasis. Decreasing GRP94 had opposite effects, potentially through yes-associated protein (YAP)/TEAD1 axis inhibition, with raised YAP phosphorylation and decreased TEAD1 levels detected by western blotting (WB). Inhibiting YAP counteracted GRP94's effects on anoikis resistance and metastasis, while activating YAP reversed the effects of GRP94 reduction. Animal experiments verified GRP94's contribution to GC's peritoneal metastasis. In conclusion, our work highlights the effect of GRP94 on anoikis resistance, showing potential value in treating peritoneal metastasis of GC.

Role of HSP90 in Type 2 Diabetes Mellitus and Its Association with Liver Diseases

Non-alcoholic fatty acid liver disease (NAFLD), non-alcoholic steatohepatitis (NASH) and hepatocellular carcinoma (HCC) are the fatal liver diseases which encompass a spectrum of disease severity associated with increased risk of type 2 diabetes mellitus (T2DM), a metabolic disorder. Heat shock proteins serve as markers in early prognosis and diagnosis of early stages of liver diseases associated with metabolic disorder. This review aims to comprehensively investigate the significance of HSP90 isoforms in T2DM and liver diseases. Additionally, we explore the collective knowledge on plant-based drug compounds that regulate HSP90 isoform targets, highlighting their potential in treating T2DM-associated liver diseases. Furthermore, this review focuses on the computational systems' biology and next-generation sequencing technology approaches that are used to unravel the potential medicine for the treatment of pleiotropy of these 2 diseases and to further elucidate the mechanism.

Impact of Gut Dysbiosis on the Risk of Non-Small-Cell Lung Cancer

Background: The imbalance of gut microbiota, dysbiosis, is associated with various malignant diseases. This study aimed to identify the characteristics of gut microbiota in age-matched treatment-naïve non-small-cell lung cancer (NSCLC) patients and healthy individuals to investigate possible gut-microbe-related pathways involved in the development of NSCLC. Methods: We enrolled 34 age-matched NSCLC patients and 268 healthy individuals. Hypervariable V3−V4 amplicons of 16S rRNA in freshly collected fecal samples were sequenced. Diversity, microbial composition, functional pathways, smoking history, and gut-microbe-related comorbidities were analyzed to assess the factors associated with the risk of NSCLC. Results: Microbial alpha diversity was decreased in the patients with NSCLC, and beta diversity was significantly different between the patients and controls (p < 0.001). After adjustments for sex, smoking history, hypertension, diabetes mellitus, chronic obstructive pulmonary disease, and 11 abundant microbes with significant differences between the patients and controls, the enrichment of Anaerotruncus spp. and Bacteroides caccae was associated with an increased risk of NSCLC (p = 0.003 and 0.007, respectively). The areas under receiver operating characteristic curves were 71.4% and 66.9% for Anaerotruncus spp. and Bacteroides caccae, respectively (both p < 0.001). Furthermore, the abundance of Bacteroides caccae was positively correlated with steroid hormone biosynthesis (p < 0.001), N-glycan biosynthesis (p = 0.023), glycosaminoglycan degradation (p < 0.001), lipoic acid metabolism (p = 0.039), peroxisome (p < 0.001), and apoptosis (p < 0.001), but inversely related to glycerolipid metabolism (p < 0.001). Anaerotruncus spp. was positively associated with decreased biosynthesis of ansamycin only (p = 0.001). No overlapping signaling pathways were modulated by Bacteroides caccae or Anaerotruncus spp. Conclusions: Our results revealed that fecal Anaerotruncus spp. and Bacteroides caccae were abundant and may be associated with the risk of NSCLC regardless of sex, smoking history, and gut-microbe-related comorbidities. Further investigations on the mechanism underlying the potential association between gut dysbiosis and the development of NSCLC are warranted.

E3 Ubiquitin Ligase CHIP Inhibits the Interaction between Hsp90β and MAST1 to Repress Radiation Resistance in Non-Small-Cell Lung Cancer Stem Cells

The radiation resistance of cancer stem cells poses a critical obstacle for management of non-small-cell lung cancer (NSCLC). It is interesting to note that E3 ubiquitin ligase CHIP is involved in radiation resistance and stemness phenotypes in NSCLC, while the downstream mechanisms remain elusive. Therefore, this study is aimed at exploring the possible molecular mechanism of E3 ubiquitin ligase CHIP in radiation resistance of NSCLC stem cells. Cancer and adjacent normal tissues of NSCLC patients were collected to determine expression of CHIP, Hsp90β, and MAST1. CD133⁺ cells were isolated from the NSCLC tissues and the lung cancer cell line A549 by flow cytometric sorting. Accordingly, downregulated CHIP and upregulated Hsp90β and MAST1 were observed in cancer tissues from NSCLC patients and in NSCLC stem cells. Sphere formation assay, colony formation assay, and flow cytometry were performed to examine self-renewal ability, survival, and apoptosis of NSCLC stem cells. An animal model of tumor xenograft was developed in nude mice to observe the tumorigenic ability and radiation resistance of NSCLC stem cells. CHIP overexpression was demonstrated to inhibit the NSCLC stem cell properties and radiation resistance in vitro and in vivo. Mechanistically, CHIP promoted MAST1 ubiquitination by blocking Hsp90β interaction with MAST1, thus inhibiting MAST1 protein stability. Furthermore, CHIP-mediated downregulation of MAST1 protein stability inhibited the NSCLC stem cell properties and radiation resistance. Collectively, CHIP promotes the ubiquitination of MAST1 by blocking the interaction of Hsp90β with MAST1, leading to decreased MAST1 protein stability, which suppressed NSCLC stem cell properties and radiation resistance.

Cytosolic Hsp90 Isoform-Specific Functions and Clinical Significance

The heat shock protein 90 (Hsp90) is a molecular chaperone and a key regulator of proteostasis under both physiological and stress conditions. In mammals, there are two cytosolic Hsp90 isoforms: Hsp90α and Hsp90β. These two isoforms are 85% identical and encoded by two different genes. Hsp90β is constitutively expressed and essential for early mouse development, while Hsp90α is stress-inducible and not necessary for survivability. These two isoforms are known to have largely overlapping functions and to interact with a large fraction of the proteome. To what extent there are isoform-specific functions at the protein level has only relatively recently begun to emerge. There are studies indicating that one isoform is more involved in the functionality of a specific tissue or cell type. Moreover, in many diseases, functionally altered cells appear to be more dependent on one particular isoform. This leaves space for designing therapeutic strategies in an isoform-specific way, which may overcome the unfavorable outcome of pan-Hsp90 inhibition encountered in previous clinical trials. For this to succeed, isoform-specific functions must be understood in more detail. In this review, we summarize the available information on isoform-specific functions of mammalian Hsp90 and connect it to possible clinical applications.

Novel matrinic acid derivatives bearing 2-anilinothiazole structure for non-small cell lung cancer treatment with improved Hsp90 targeting effect

Involved in mediating the folding and maturation of more than 300 client proteins, many of which are oncoproteins, Hsp90 has emerged as a promising drug target for cancer therapy. In particular, inhibiting Hsp90 plays a vital role in the treatment of non-small cell lung cancer. Owing to undesirable outcomes of Hsp90 inhibitors in clinical trials, a series of matrinic acid compounds bearing 2-anilinothiazole moiety were designed based on the structural features allocation shared among Hsp90 inhibitors within the ATP-binding pocket. Most of the compounds showed potent anticancer activities validated by MTT assay. Among them, the most potent compound C4 (IC₅₀  < 10 μM against four cell lines) was chosen for further mechanism study. Notably, C4 showed a better safety profile than 17AAG with a higher SI value. Thermal shift assay data indicated C4 exhibited a strong binding affinity with Hsp90 (-18.85 ± 0.56°C) comparable to radicicol. Mechanism studies verified that C4 significantly inhibited proliferation and migration activities of A549 cells. Besides, C4 can induce a prolonged G1-phase and cell apoptosis. Western blot analysis results indicated C4 could moderately suppress Hsp90 and upregulate Hsp70 expression. Furthermore, the downregulated trend of the client proteins of Hsp90, such as β-Catenin and Bcl-2, were consistent with the cellular effect of C4, suggesting that C4 could exert anticancer activity via targeting Hsp90. In the xenograft model in vivo, C4 effectively inhibited lung cancer growth without obvious side effects. Collectively, C4 could be a promising therapeutic agent for lung cancer and the novel scaffold provided new insights into the design of Hsp90 inhibitors.

Hsp90 in Human Diseases: Molecular Mechanisms to Therapeutic Approaches

The maturation of hemeprotein dictates that they incorporate heme and become active, but knowledge of this essential cellular process remains incomplete. Studies on chaperon Hsp90 has revealed that it drives functional heme maturation of inducible nitric oxide synthase (iNOS), soluble guanylate cyclase (sGC) hemoglobin (Hb) and myoglobin (Mb) along with other proteins including GAPDH, while globin heme maturations also need an active sGC. In all these cases, Hsp90 interacts with the heme-free or apo-protein and then drives the heme maturation by an ATP dependent process before dissociating from the heme-replete proteins, suggesting that it is a key player in such heme-insertion processes. As the studies on globin maturation also need an active sGC, it connects the globin maturation to the NO-sGC (Nitric oxide-sGC) signal pathway, thereby constituting a novel NO-sGC-Globin axis. Since many aggressive cancer cells make Hbβ/Mb to survive, the dependence of the globin maturation of cancer cells places the NO-sGC signal pathway in a new light for therapeutic intervention. Given the ATPase function of Hsp90 in heme-maturation of client hemeproteins, Hsp90 inhibitors often cause serious side effects and this can encourage the alternate use of sGC activators/stimulators in combination with specific Hsp90 inhibitors for better therapeutic intervention.

Protective Role of Genetic Variants in HSP90 Genes-Complex in COPD Secondary to Biomass-Burning Smoke Exposure and Non-Severe COPD Forms in Tobacco Smoking Subjects

Background: Chronic Obstructive Pulmonary Disease (COPD) is an inflammatory disease characterized by airflow obstruction, commonly present in smokers and subjects exposed to noxious particles product of biomass-burning smoke (BBS). Several association studies have identified single-nucleotide polymorphisms (SNP) in coding genes related to the heat shock proteins family-genes that codify the heat shock proteins (Hsp). Hsp accomplishes critical roles in regulating immune response, antigen-processing, eliminating protein aggregates and co-activating receptors. The presence of SNPs in these genes can lead to alterations in immune responses. We aimed to evaluate the association of SNPs in the HSP90 gene complex and COPD. Methods: We enrolled 1549 participants, divided into two comparison groups; 919 tobacco-smoking subjects (cases COPD-TS n = 294 and, controls SWOC n = 625) and 630 chronic exposed to BBS (cases COPD-BBS n = 186 and controls BBES n = 444). We genotyped 2 SNPs: the rs13296 in HSP90AB1 and rs2070908 in HSP90B1. Results: Through the dominant model (GC + CC), the rs2070908 is associated with decreased risk (p < 0.01, OR = 0.6) to suffer COPD among chronic exposed BBS subjects. We found an association between rs13296 GG genotype and lower risk (p = 0.01, OR = 0.22) to suffer severe COPD-TS forms in the severity analysis. Conclusions: single-nucleotide variants in the HSP90AB1 and HSP90B1 genes are associated with decreased COPD risk in subjects exposed to BBS and the most severe forms of COPD in tobacco-smoking subjects.

Hsp90 inhibitor gedunin causes apoptosis in A549 lung cancer cells by disrupting Hsp90:Beclin-1:Bcl-2 interaction and downregulating autophagy

AIMS

Hsp90 is regarded as an important therapeutic target in cancer treatment. Client proteins of Hsp90 like Beclin-1, PI3K, and AKT, are associated with tumor development, poor prognosis, and resistance to cancer therapies. This study aims to analyze the role of Gedunin, an Hsp-90 inhibitor, in mediation of crosstalk between apoptosis and autophagy by targeting Beclin-1:Bcl-2 interaction, and ER stress.

MAIN METHODS

A549 cells were treated with different concentrations of gedunin, and inhibitory rate was evaluated by MTT assay. Effect of gedunin on generation of reactive oxygen species, mitochondrial membrane potential, and chromatin condensation was studied by staining methods like DCFH-DA, MitoTracker, and DAPI. Expression of EGFR, PIK3CA, AKT, marker genes for apoptosis and autophagy were studied using semi-quantitative RT-PCR. Interaction study of Hsp90:Beclin-1:Bcl-2 was done by immunoprecipitation analysis. Protein expression of autophagy and apoptosis markers along with Grp78, Hsp70, and Hsp90 was analyzed by immunoblotting.

KEY FINDINGS

Gedunin exerts cytotoxic effects, causes increase in ROS generation, downregulates mitochondrial membrane potential and induces loss in DNA integrity. mRNA expression analysis revealed that gedunin sensitized A549 cells towards apoptosis by downregulating EGFR, PIK3CA, AKT, and autophagy. Gedunin also inhibited interaction between Hsp90:Beclin-1:Bcl-2, leading to downregulation of autophagy (Beclin-1, Atg5-12 complex, and LC3) and antiapoptotic protein Bcl-2, which may result in ER stress-induced apoptosis. Moreover, Hsp90 inhibition by gedunin did not cause upregulation of Hsp70 expression.

SIGNIFICANCE

Gedunin induces apoptosis in lung cancer cells by disrupting Hsp90:Beclin-1:Bcl-2 interaction and autophagy downregulation, thus making gedunin a good drug lead for targeting lung cancer.

Heat shock protein 90-targeted photodynamic therapy enables treatment of subcutaneous and visceral tumors

Photodynamic therapy (PDT) ablates malignancies by applying focused near-infrared (nIR) light onto a lesion of interest after systemic administration of a photosensitizer (PS); however, the accumulation of existing PS is not tumor-exclusive. We developed a tumor-localizing strategy for PDT, exploiting the high expression of heat shock protein 90 (Hsp90) in cancer cells to retain high concentrations of PS by tethering a small molecule Hsp90 inhibitor to a PS (verteporfin, VP) to create an Hsp90-targeted PS (HS201). HS201 accumulates to a greater extent than VP in breast cancer cells both in vitro and in vivo, resulting in increased treatment efficacy of HS201-PDT in various human breast cancer xenografts regardless of molecular and clinical subtypes. The therapeutic index achieved with Hsp90-targeted PDT would permit treatment not only of localized tumors, but also more diffusely infiltrating processes such as inflammatory breast cancer.

Elevated Hsp90-beta contributes to differential diagnosis of pleural effusion caused by lung cancer and correlates with malignant biological behavior of lung cancer

Background

Hsp90-beta has been investigated to be correlated with the occurrence and development of tumor. The intention of this research was to test the level of Hsp90-beta in malignant pleural effusion (MPE) of patients with lung cancer and disclose the clinical significance of Hsp90-beta as a potential tumor marker for differential diagnosis of pleural effusion caused by lung cancer.

Methods

The level of Hsp90-beta was determined using enzyme-linked immunosorbent assay. Calculations of the Hsp90-beta threshold, the sensitivity and specificity for distinguishing MPE from benign pleural effusion were performed using receiver operator characteristic curve.

Results

The level of Hsp90-beta in MPE of lung cancer patients was higher than that in control individuals (P < 0.05) and increased MPE Hsp90-beta was correlated with the pathological differentiation, tumor size and lymphatic metastasis (P < 0.05). The cutoff value of Hsp90-beta produced by receiver operator characteristic curve for distinguishing lung cancer from control individuals were 1.659 ng/mL and the sensitivity and specificity were 93.46 and 79%.

Conclusions

Increased Hsp90-beta in MPE was correlated with malignant biological behavior of lung cancer patients, indicating that the level of Hsp90-beta could be a tool of referential value for differential diagnosis of pleural effusion caused by lung cancer.

Hsp90ab1 stabilizes LRP5 to promote epithelial-mesenchymal transition via activating of AKT and Wnt/β-catenin signaling pathways in gastric cancer progression

Hsp90ab1 is upregulated in numerous solid tumors, which is thought to induce the angiogenesis and promote cancer metastasis. However, it’s actions in gastric cancer (GC) has not been exhibited. In this study, Hsp90ab1 was demonstrated to be overexpressed and correlated with the poor prognosis, proliferation and invasion of GC. Ectopic expression of Hsp90ab1 promoted the proliferation and metastasis of GC cells both in vitro in cell line models of GC and in vivo using two different xenograft mouse models, while opposite effects were observed in Hsp90ab1 silenced cells. Moreover, the underlining molecular mechanism was explored by the co-immunoprecipitation, immunofluorescence, GST pull-down and in vitro ubiquitination assay. Namely, Hsp90ab1 exerted these functions via the interaction of LRP5 and inhibited ubiquitin-mediated degradation of LRP5, an indispensable coreceptor of the Wnt/β-catenin signaling pathway. In addition, the crosstalk between Hsp90ab1 and LRP5 contributed to the upregulation of multiple mesenchymal markers, which are also targets of Wnt/β-catenin. Collectively, this study uncovers the details of the Hsp90ab1-LRP5 axis, providing novel insights into the role and mechanism of invasion and metastasis in GC.

Grp94 in complexes with IgG is a soluble diagnostic marker of gastrointestinal tumors and displays immune-stimulating activity on peripheral blood immune cells

Glucose-regulated protein94 (Grp94), the most represented endoplasmic reticulum (ER)-resident heat shock protein (HSP), is a tumor antigen shared by different types of solid and hematological tumors. The tumor-specific feature of Grp94 is its translocation from the ER to the cell surface where it displays pro-oncogenic functions. This un-physiological location has important implications for both the tumor pathology and anti-tumor therapy. We wanted to address the question of whether Grp94 could be measured as liquid marker in cancer patients in order to make predictions of diagnostic and therapeutic relevance for the tumor. To this aim, we performed an in-depth investigation on patients with primary tumors of the gastrointestinal (GI) tract, using different methodological approaches to detect Grp94 in tumor tissues, plasma and peripheral blood mononuclear cells (PBMCs). Results indicate that Grp94 is not only the antigen highly expressed in any tumor tissue and in cells of tumor infiltrates, mostly B lymphocytes, but it is also found in the circulation. However, the only form in which Grp94 was detected in the plasma of any patients and in B lymphocytes induced to proliferate, was that of stable complexes with Immunoglobulin (Ig)G. Using a specific immune-enzyme assay to measure plasma Grp94-IgG complexes, we showed that Grp94-IgG complexes were significantly increased in cancer patients compared to healthy control subjects, serving as diagnostic tumor biomarker. Results also demonstrate that the stimulation of patient PBMCs with Grp94-IgG complexes led to an increased secretion of inflammatory cytokines that might drive a potentially beneficial anti-tumor effect.

Molecular mechanism and targeted therapy of Hsp90 involved in lung cancer: New discoveries and developments (Review)

The exploration of the molecular mechanisms and signaling pathways on lung cancer is very important for developing new strategies of diagnosis and treatment to this disease, such as finding valuable lung cancer markers and molecularly targeted therapies. Previously, a number of studies disclose that heat shock protein 90 (Hsp90) is upregulated in cancer cells, tissues and serum of lung cancer patients, and its upregulation intimately correlates with the occurrence, development and outcome of lung cancer. On the contrary, inhibition of Hsp90 can suppress cell proliferation, motility and metastasis of lung cancer and promote apoptosis of lung cancer cells via complex signaling pathways. In addition, a series of Hsp90 inhibitors have been investigated as effective molecular targeted therapy tactics fighting against lung cancer. This review, systematically summarizes the role of Hsp90 in lung cancer, the molecular mechanisms and development of anti-Hsp90 treatment in lung cancer.