Ganetespib (STA-9090), a nongeldanamycin HSP90 inhibitor, has potent antitumor activity in in vitro and in vivo models of non-small cell lung cancer

Hiding in plain sight: Optimizing topoisomerase IIα inhibitors into Hsp90β selective binders

Due to their impact on several oncogenic client proteins, the Hsp90 family of chaperones has been widely studied for the development of potential anticancer agents. Although several Hsp90 inhibitors have entered clinical trials, most were unsuccessful because they induced a heat shock response (HSR). This issue can be circumvented by using isoform-selective inhibitors, but the high similarity in the ATP-binding sites between the isoforms presents a challenge. Given that Hsp90 shares a conserved Bergerat fold with bacterial DNA gyrase B and human topoisomerase IIα, we repurposed our ATP-competitive inhibitors of these two proteins for Hsp90 inhibition. We virtually screened a library of in-house inhibitors and identified eleven hits for evaluation of Hsp90 binding. Among these, compound 11 displayed low micromolar affinity for Hsp90 and demonstrated a 12-fold selectivity for Hsp90β over its closest isoform, Hsp90α. Out of 29 prepared analogs, 16 showed a preference for Hsp90β over Hsp90α. Furthermore, eleven of these compounds inhibited the growth of several cancer cell lines in vitro. Notably, compound 24e reduced intracellular levels of Hsp90 client proteins in MCF-7 cells, leading to cell cycle arrest in the G0/G1 phase without inducing HSR. This inhibitor exhibited at least a 27-fold preference for Hsp90β and was selective against topoisomerase IIα, a panel of 22 representative protein kinases, and proved to be non-toxic in a zebrafish larvae toxicology model. Finally, molecular modeling, corroborated by STD NMR studies, and the binding of 24e to the S52A mutant of Hsp90α confirmed that the serine to alanine switch drives the selectivity between the two cytoplasmic isoforms.

An update on the status of HSP90 inhibitors in cancer clinical trials

The evolutionary conserved molecular chaperone heat shock protein 90 (HSP90) plays an indispensable role in tumorigenesis by stabilizing client oncoproteins. Although the functionality of HSP90 is tightly regulated, cancer cells exhibit a unique dependence on this chaperone, leading to its overexpression, which has been associated with poor prognosis in certain malignancies. While various strategies targeting heat shock proteins (HSPs) involved in carcinogenesis have been explored, only inhibition of HSP90 has consistently and effectively resulted in proteasomal degradation of its client proteins. To date, a total of 22 HSP90 inhibitors (HSP90i) have been tested in 186 cancer clinical trials, as reported by clinicaltrials.gov. Among these trials, 60 % have been completed, 10 % are currently active, and 30 % have been suspended, terminated, or withdrawn. HSP90 inhibitors (HSP90i) have been used as single agents or in combination with other drugs for the treatment of various cancer types in clinical trials. Notably, improved clinical outcomes have been observed when HSP90i are used in combination therapies, as they exhibit a synergistic antitumor effect. However, as single agents, HSP90i have shown limited clinical activity due to drug-related toxicity or therapy resistance. Recently, active trials conducted in Japan evaluating TAS-116 (pimitespib) have demonstrated promising results with low toxicity as monotherapy and in combination with the immune checkpoint inhibitor nivolumab. Exploratory biomarker analyses performed in various trials have demonstrated target engagement that suggests the potential for identifying patient populations that may respond favorably to the therapy. In this review, we discuss the advances made in the past 5 years regarding HSP90i and their implications in anticancer therapeutics. Our focus lies in evaluating drug efficacy, prognosis forecast, pharmacodynamic biomarkers, and clinical outcomes reported in published trials. Through this comprehensive review, we aim to shed light on the progress and potential of HSP90i as promising therapeutic agents in cancer treatment.

Targeting apoptotic pathways for cancer therapy

Apoptosis is a form of programmed cell death that is mediated by intrinsic and extrinsic pathways. Dysregulation of and resistance to cell death are hallmarks of cancer. For over three decades, the development of therapies to promote treatment of cancer by inducing various cell death modalities, including apoptosis, has been a main goal of clinical oncology. Apoptosis pathways also interact with other signaling mechanisms, such as the p53 signaling pathway and the integrated stress response (ISR) pathway. In addition to agents directly targeting the intrinsic and extrinsic pathway components, anticancer drugs that target the p53 and ISR signaling pathways are actively being developed. In this Review, we discuss selected and promising anticancer therapies in various stages of development, including drug targets, mechanisms, and resistance to related treatments, focusing especially on B cell lymphoma 2 (BCL-2) inhibitors, TRAIL analogues, DR5 antibodies, and strategies that target p53, mutant p53, and the ISR.

Combined treatment with cetuximab and STA9090 has synergistic anticancer effects on human non-small cell lung cancer

Cetuximab (CET), a human murine chimeric IgG monoclonal antibody and an inhibitor of epidermal growth factor receptor (EGFR), has been shown to be effective in treating various types of cancer. However, its use is hindered by limitations such as resistance development, variability in patient response, side effects, and challenges in biomarker identification. Therefore, CET is often combined with other targeted therapies or chemotherapies to enhance its effectiveness. In this study, we investigate the anticancer effects and underlying mechanisms of the combination of CET, an EGFR inhibitor, and STA9090, an inhibitor of heat shock protein 90 (Hsp90), in both in vitro and in vivo models of non-small cell lung cancer (NSCLC). The results demonstrate significantly stronger effects on NSCLC cells in response to combination therapy than to treatment with either agent alone, indicating that the combination of CET and STA9090 has potential synergistic effects. Additionally, the combination therapy inhibits tumor growth in a xenograft nude mouse model more effectively than treatment with either agent alone, suggesting improved efficacy when used together. Furthermore, the synergistic effects of the combination therapy are likely due to inactivation of the receptor tyrosine kinase (RTK) pathway, which is overly activated in cancer and contributes to tumor growth, angiogenesis, and metastasis. Consequently, our findings suggest that STA9090 has potent direct antitumor activity and synergizes with CET against NSCLC tumors. It is highly likely that these synergistic effects are mediated through RTK pathway inactivation caused by the combination. Therefore, our findings strongly and consistently support the potential synergistic effect of STA9090, an RTK inhibitor, in combination with EGFR-targeting agents.

DDCM: A Computational Strategy for Drug Repositioning Based on Support-Vector Regression Algorithm

Computational drug-repositioning technology is an effective tool for speeding up drug development. As biological data resources continue to grow, it becomes more important to find effective methods to identify potential therapeutic drugs for diseases. The effective use of valuable data has become a more rational and efficient approach to drug repositioning. The disease-drug correlation method (DDCM) proposed in this study is a novel approach that integrates data from multiple sources and different levels to predict potential treatments for diseases, utilizing support-vector regression (SVR). The DDCM approach resulted in potential therapeutic drugs for neoplasms and cardiovascular diseases by constructing a correlation hybrid matrix containing the respective similarities of drugs and diseases, implementing the SVR algorithm to predict the correlation scores, and undergoing a randomized perturbation and stepwise screening pipeline. Some potential therapeutic drugs were predicted by this approach. The potential therapeutic ability of these drugs has been well-validated in terms of the literature, function, drug target, and survival-essential genes. The method's feasibility was confirmed by comparing the predicted results with the classical method and conducting a co-drug analysis of the sub-branch. Our method challenges the conventional approach to studying disease-drug correlations and presents a fresh perspective for understanding the pathogenesis of diseases.

Effect of resveratrol on herpesvirus encephalitis: Evidences for its mechanisms of action

BACKGROUND

Herpes simplex virus type 1 (HSV-1)-induced herpes simplex encephalitis (HSE) has a high mortality rate in clinically immunocompromised patients, while recovered patients often experience neurological sequelae due to neuroinflammation. Nucleoside drugs and nucleoside analogues such as acyclovir and ganciclovir are mainly used in clinical treatment, and the emergence of resistant viral strains makes the development of new anti-herpesvirus encephalitis drugs urgent. Resveratrol is a multifunctional, plant-derived bioactive compound and its antiviral potential is attracting much attention.

PURPOSE

This study aimed to investigate the anti-HSV-1 mechanism of resveratrol in microglial cells and in the HSE mouse model.

METHODS

The antiviral effect of resveratrol on HSV-1 infection was investigated by plaque assay, virus titer, immunofluorescence, Western blot and time-of-addition assay. The influence of resveratrol on stimulator of interferon gene (STING)/Nuclear Factor kappa B (NF-κB) signaling pathway-mediated neuroinflammation was examined by Western blot, RT-qPCR and ELISA. The interaction between resveratrol and STING/heat shock protein 90 beta (HSP90β) was evaluated by molecular modeling, co-immunoprecipitation, and drug affinity responsive target stability assay. The therapeutic effect of resveratrol on HSE was evaluated in the HSE mouse model by analyzing weight loss, neurodegenerative symptoms and histopathological scores.

RESULTS

Resveratrol inhibited the early process of HSV-1 infection, and interfered with the STING/NF-κB signaling pathway to attenuate HSV-1-induced neuroinflammation and microglial M1 polarization, independent of its classical target Sirtuin1. Mechanistically, resveratrol completely bound to Glu515 and Lys491 of HSP90β, thus disrupting the HSP90β-STING interaction and promoting STING degradation. Resveratrol also significantly alleviated viral encephalitis and neuroinflammation caused by HSV-1 in the HSE mouse model.

CONCLUSION

Resveratrol acted as a non-classical HSP90β inhibitor, binding to the STING-HSP90β interaction site to promote STING degradation and attenuate HSV-1-induced encephalitis and neuroinflammation. These findings suggest the alternative strategy of targeting HSP90β and resveratrol-mediated inhibition of HSP90β as a potential antiviral approach.

Viral Evolution Shaped by Host Proteostasis Networks

Understanding the factors that shape viral evolution is critical for developing effective antiviral strategies, accurately predicting viral evolution, and preventing pandemics. One fundamental determinant of viral evolution is the interplay between viral protein biophysics and the host machineries that regulate protein folding and quality control. Most adaptive mutations in viruses are biophysically deleterious, resulting in a viral protein product with folding defects. In cells, protein folding is assisted by a dynamic system of chaperones and quality control processes known as the proteostasis network. Host proteostasis networks can determine the fates of viral proteins with biophysical defects, either by assisting with folding or by targeting them for degradation. In this review, we discuss and analyze new discoveries revealing that host proteostasis factors can profoundly shape the sequence space accessible to evolving viral proteins. We also discuss the many opportunities for research progress proffered by the proteostasis perspective on viral evolution and adaptation.

Design, synthesis, and biological activity of dual monoamine oxidase A and heat shock protein 90 inhibitors, N-Methylpropargylamine-conjugated 4-isopropylresorcinol for glioblastoma

Monoamine oxidase A (MAO A) and heat shock protein 90 (HSP90) inhibitors have been shown to decrease the progression of glioblastoma (GBM) and other cancers. In this study, a series of MAO A/HSP90 dual inhibitors were designed and synthesized in the hope to develop more effective treatment of GBM. Compounds 4-b and 4-c are conjugates of isopropylresorcinol (pharmacophore of HSP90 inhibitor) with the phenyl group of clorgyline (MAO A inhibitor) by a tertiary amide bond substituted with methyl (4-b) or ethyl (4-c) group, respectively. They inhibited MAO A activity, HSP90 binding, and the growth of both TMZ-sensitive and -resistant GBM cells. Western blots showed that they increased HSP70 expression indicating reduced function of HSP90, reduced HER2 and phospho-Akt expression similar to MAO A or HSP90 inhibitor itself. Both compounds decreased IFN-γ induced PD-L1 expression in GL26 cells, suggesting they can act as immune checkpoint inhibitor. Further, they reduced tumor growth in GL26 mouse model. NCI-60 analysis showed they also inhibited the growth of colon cancer, leukemia, non-small cell lung and other cancers. Taken together, this study demonstrates MAO A/HSP90 dual inhibitors 4-b and 4-c reduced the growth of GBM and other cancers, and they have potential to inhibit tumor immune escape.

The effects of STA-9090 (Ganetespib) and venetoclax (ABT-199) combination on apoptotic pathways in human cervical cancer cells

Combined chemotherapy is recommended strategy as a first-line treatment method in patients with cervical cancer. Ganetespib (STA-9090) is a second-generation heat shock protein 90 (Hsp90) inhibitor that blocks the ATPase function of Hsp90 and inhibits the proper folding of oncogenic client proteins. Venetoclax (ABT-199) is an orally bioavailable Bcl-2 (B-cell lymphoma 2) inhibitor that stimulates apoptotic signaling pathways in cancer cells. This study evaluated the anticancer effects of STA-9090 combined with Venetoclax in the human cervical cancer cell line (HeLa). The human cervical cancer cells were treated with STA-9090, Venetoclax, and Sta-9090 plus Venetoclax for 48 h, and cell viability was measured using the XTT assay. The alteration of the Hsp90 protein expression level and the chaperone activity of HSP90 were detected by ELISA and luciferase aggregation assay, respectively. For the apoptotic process, qRT-PCR was applied to study Bcl-2-associated X protein (Bax), B-cell lymphoma 2 (Bcl-2), Bcl-2-like protein 1 (Bcl-xL ), Cytochrome c (Cyt-c), Caspase3 (Cas-3), and Caspase7 (Cas-7) expression levels after drug treatments. Also, a colorimetric Cas-3 activity assay was performed to detect the induction of the apoptosis process. Our results demonstrated that 8 nM of STA-9090 combined with 4 µM of Venetoclax synergistically inhibited cervical cancer cell proliferation more than STA-9090 or Venetoclax alone after 48 h of treatment. STA-9090 and Venetoclax combination decreased the protein expression level of Hsp90 and significantly inhibited chaperone activity of Hsp90. This combination stimulated apoptosis in cervical cancer cells by down-regulating of anti-apoptotic markers while inducing pro-apoptotic markers. Also, the STA-9090-Venetoclax combination increased Cas-3 activity in Hela cells. Collectively, these findings pointed out that the STA-9090-Venetoclax combination exhibited more activity than the individual drugs to stimulate toxicity and apoptosis in cervical cancer cells based on HSP90 inhibition.

Ganetespib (STA-9090) augments sorafenib efficacy via necroptosis induction in hepatocellular carcinoma: Implications from preclinical data for a novel therapeutic approach

Sorafenib, a multikinase inhibitor, is a first-line treatment for advanced hepatocellular carcinoma, but its long-term effectiveness is limited by the emergence of resistance mechanisms. One such mechanism is the reduction of microvessel density and intratumoral hypoxia caused by prolonged sorafenib treatment. Our research has demonstrated that HSP90 plays a critical role in conferring resistance to sorafenib in HepG2 cells under hypoxic conditions and N-Nitrosodiethylamine-exposed mice as well. This occurs through the inhibition of necroptosis on the one hand and the stabilization of HIF-1α on the other hand. To augment the effects of sorafenib, we investigated the use of ganetespib, an HSP90 inhibitor. We found that ganetespib activated necroptosis and destabilized HIF-1α under hypoxia, thus enhancing the effectiveness of sorafenib. Additionally, we discovered that LAMP2 aids in the degradation of MLKL, which is the mediator of necroptosis, through the chaperone-mediated autophagy pathway. Interestingly, we observed a significant negative correlation between LAMP2 and MLKL. These effects resulted in a reduction in the number of surface nodules and liver index, indicating a regression in tumor production rates in mice with HCC. Furthermore, AFP levels decreased. Combining ganetespib with sorafenib showed a synergistic cytotoxic effect and resulted in the accumulation of p62 and inhibition of macroautophagy. These findings suggest that the combined therapy of ganetespib and sorafenib may offer a promising approach for the treatment of hepatocellular carcinoma by activating necroptosis, inhibiting macroautophagy, and exhibiting a potential antiangiogenic effect. Overall, continued research is critical to establish the full therapeutic potential of this combination therapy.

Following the design path of isoform-selective Hsp90 inhibitors: Small differences, great opportunities

The heat shock protein 90 (Hsp90) family consists of four highly conserved isoforms: the mitochondrial TRAP-1, the endoplasmic reticulum-localised Grp94, and the cytoplasmic Hsp90α and Hsp90β. Since the late 1990s, this family has been extensively studied as a potential target for the treatment of cancer, neurological disorders, and infectious diseases. The initial approach was to develop non-selective, so-called pan-Hsp90 ATP-competitive inhibitors of the N-terminal domain. Many of these agents were tested in clinical trials, mainly for the treatment of cancer, but none of them succeeded in the clinic. This was mainly due to the lack of efficacy and various toxicities associated with the induction of heat shock response (HSR). This lack of success has prompted a turn to new approaches of Hsp90 inhibition. Thus, inhibitors selective for a particular isoform of Hsp90 have been developed. These isoform-selective inhibitors do not induce HSR and have a more targeted effect because not all client proteins are equally dependent on all four paralogues of Hsp90. However, it is extremely difficult to develop such selective compounds because the family is highly conserved. Hsp90α and Hsp90β have an amazing 95% identity of the N-terminal ATP binding site, differing only in two amino acid residues. Therefore, the focus of this review is to fully elucidate the key structural features of the selective inhibitor classes in terms of binding site dissimilarities. In addition to a methodological characterisation of the structure-activity relationships, the main advantages of selective inhibition of the TRAP-1, Grp94, Hsp90α and Hsp90β isoforms are discussed.

Ganetespib with Methotrexate Acts Synergistically to Impede NF-κB/p65 Signaling in Human Lung Cancer A549 Cells

Among the various types of cancer, lung cancer accounts for the highest number of fatalities across the globe. A combination of different cancer chemotherapeutics is regarded as an effective strategy for clinical management of different cancers. Ganetespib (GAN) is a well-established hsp90 inhibitor with enhanced pharmacological properties in comparison with its first-generation counterparts. Previous preclinical studies have shown that GAN exerts significant effects against cancer cells; however, its therapeutic effects against non-small cell lung cancer (NSCLC) A549 cells, achieved by modulating the expression of the NF-κB/p65 signaling pathway, remains unexplored. In this study, the combinatorial effect of GAN and methotrexate (MTX) against lung carcinomas was investigated through both in silico and in vitro studies. A combinatorial treatment regimen of GAN/MTX exerted more significant cytotoxic effects (p < 0.001) against A549 cells than individual treatments. The GAN/MTX combination also instigated nuclear fragmentation followed by augmentation in intracellular ROS levels (p < 0.001). The elevated ROS in A549 cells upon exposure to GAN/MTX combinatorial regimen was concomitantly accompanied with a remarkable reduction in mitochondrial viability. In addition, it was observed that the GAN/MTX combination succeeded in elevating caspase-3 activity and downregulating the expression levels of anti-apoptotic mediators Bcl2 and survivin in NSCLC A549 cells. Most importantly, the GAN/MTX combinatorial regimen impeded the activation of the NF-kB/p65 signaling pathway via repression of the expression of E-cadherin and N-cadherin, which was confirmed by molecular docking studies. Collectively, these findings demonstrated the synergistic effect of the GAN/MTX combinatorial regimen in suppressing the growth of A549 cells by modulating the NF-κB/p65 signaling pathway.

Drugs Targeting p53 Mutations with FDA Approval and in Clinical Trials

Mutations in the tumor suppressor p53 (p53) promote cancer progression. This is mainly due to loss of function (LOS) as a tumor suppressor, dominant-negative (DN) activities of missense mutant p53 (mutp53) over wild-type p53 (wtp53), and wtp53-independent oncogenic activities of missense mutp53 by interacting with other tumor suppressors or oncogenes (gain of function: GOF). Since p53 mutations occur in ~50% of human cancers and rarely occur in normal tissues, p53 mutations are cancer-specific and ideal therapeutic targets. Approaches to target p53 mutations include (1) restoration or stabilization of wtp53 conformation from missense mutp53, (2) rescue of p53 nonsense mutations, (3) depletion or degradation of mutp53 proteins, and (4) induction of p53 synthetic lethality or targeting of vulnerabilities imposed by p53 mutations (enhanced YAP/TAZ activities) or deletions (hyperactivated retrotransposons). This review article focuses on clinically available FDA-approved drugs and drugs in clinical trials that target p53 mutations and summarizes their mechanisms of action and activities to suppress cancer progression.

Prognosis and personalized treatment prediction in lung adenocarcinoma: An in silico and in vitro strategy adopting cuproptosis related lncRNA towards precision oncology

Background: There is a rapid increase in lung adenocarcinomas (LUAD), and studies suggest associations between cuproptosis and the occurrence of various types of tumors. However, it remains unclear whether cuproptosis plays a role in LUAD prognosis. Methods: Dataset of the TCGA-LUAD was treated as training cohort, while validation cohort consisted of the merged datasets of the GSE29013, GSE30219, GSE31210, GSE37745, and GSE50081. Ten studied cuproptosis-related genes (CRG) were used to generated CRG clusters and CRG cluster-related differential expressed gene (CRG-DEG) clusters. The differently expressed lncRNA that with prognosis ability between the CRG-DEG clusters were put into a LASSO regression for cuproptosis-related lncRNA signature (CRLncSig). Kaplan-Meier estimator, Cox model, receiver operating characteristic (ROC), time-dependent AUC (tAUC), principal component analysis (PCA), and nomogram predictor were further deployed to confirm the model's accuracy. We examined the model's connections with other forms of regulated cell death, including apoptosis, necroptosis, pyroptosis, and ferroptosis. The immunotherapy ability of the signature was demonstrated by applying eight mainstream immunoinformatic algorithms, TMB, TIDE, and immune checkpoints. We evaluated the potential drugs for high risk CRLncSig LUADs. Real-time PCR in human LUAD tissues were performed to verify the CRLncSig expression pattern, and the signature's pan-cancer's ability was also assessed. Results: A nine-lncRNA signature, CRLncSig, was built and demonstrated owning prognostic power by applied to the validation cohort. Each of the signature genes was confirmed differentially expressed in the real world by real-time PCR. The CRLncSig correlated with 2,469/3,681 (67.07%) apoptosis-related genes, 13/20 (65.00%) necroptosis-related genes, 35/50 (70.00%) pyroptosis-related genes, and 238/380 (62.63%) ferroptosis-related genes. Immunotherapy analysis suggested that CRLncSig correlated with immune status, and checkpoints, KIR2DL3, IL10, IL2, CD40LG, SELP, BTLA, and CD28, were linked closely to our signature and were potentially suitable for LUAD immunotherapy targets. For those high-risk patients, we found three agents, gemcitabine, daunorubicin, and nobiletin. Finally, we found some of the CRLncSig lncRNAs potentially play a vital role in some types of cancer and need more attention in further studies. Conclusion: The results of this study suggest our cuproptosis-related CRLncSig can help to determine the outcome of LUAD and the effectiveness of immunotherapy, as well as help to better select targets and therapeutic agents.

Safety and efficacy of HSP90 inhibitor ganetespib for neoadjuvant treatment of stage II/III breast cancer

HSP90 inhibitors destabilize oncoproteins associated with cell cycle, angiogenesis, RAS-MAPK activity, histone modification, kinases and growth factors. We evaluated the HSP90-inhibitor ganetespib in combination with standard chemotherapy in patients with high-risk early-stage breast cancer. I-SPY2 is a multicenter, phase II adaptively randomized neoadjuvant (NAC) clinical trial enrolling patients with stage II-III breast cancer with tumors 2.5 cm or larger on the basis of hormone receptors (HR), HER2 and Mammaprint status. Multiple novel investigational agents plus standard chemotherapy are evaluated in parallel for the primary endpoint of pathologic complete response (pCR). Patients with HER2-negative breast cancer were eligible for randomization to ganetespib from October 2014 to October 2015. Of 233 women included in the final analysis, 140 were randomized to the standard NAC control; 93 were randomized to receive 150 mg/m2 ganetespib every 3 weeks with weekly paclitaxel over 12 weeks, followed by AC. Arms were balanced for hormone receptor status (51-52% HR-positive). Ganetespib did not graduate in any of the biomarker signatures studied before reaching maximum enrollment. Final estimated pCR rates were 26% vs. 18% HER2-negative, 38% vs. 22% HR-negative/HER2-negative, and 15% vs. 14% HR-positive/HER2-negative for ganetespib vs control, respectively. The predicted probability of success in phase 3 testing was 47% HER2-negative, 72% HR-negative/HER2-negative, and 19% HR-positive/HER2-negative. Ganetespib added to standard therapy is unlikely to yield substantially higher pCR rates in HER2-negative breast cancer compared to standard NAC, and neither HSP90 pathway nor replicative stress expression markers predicted response. HSP90 inhibitors remain of limited clinical interest in breast cancer, potentially in other clinical settings such as HER2-positive disease or in combination with anti-PD1 neoadjuvant chemotherapy in triple negative breast cancer.Trial registration: www.clinicaltrials.gov/ct2/show/NCT01042379.

Hsp90β inhibition upregulates interferon response and enhances immune checkpoint blockade therapy in murine tumors

Response resistance to the immune checkpoint blockade (ICB) immunotherapy remains a major clinical challenge that may be overcome through the rational combination of ICB and specific targeted therapeutics. One emerging combination strategy is based on sensitizing ICB-refractory tumors with antagonists of 90kD heat shock protein (Hsp90) that target all four isoforms. However, pan-Hsp90 inhibitors are limited by the modest efficacy, on-target and off-tumor toxicities, and induction of the heat shock response (HSR) that overrides the effect of Hsp90 inhibition. Recently, we developed Hsp90β-selective inhibitors that were cytotoxic to cancer cells but did not induce HSR in vitro. Here, we report that the Hsp90β inhibitor NDNB1182 downregulated CDK4 (an Hsp90β-dependent client protein) and induced the expression of endogenous retroviral elements and interferon-stimulated genes. In syngeneic mouse models of prostate cancer and breast cancer, NDNB1182 significantly augmented the efficacy of ICB therapy. Furthermore, NDNB1182 showed superior tolerability to the pan-Hsp90 inhibitor Ganetespib in mice. Our findings provide evidence that Hsp90β inhibition is a potentially effective and safe regimen to combine with ICB to treat immunotherapy-refractory solid tumors.

NeRD: a multichannel neural network to predict cellular response of drugs by integrating multidimensional data

BACKGROUND

Considering the heterogeneity of tumors, it is a key issue in precision medicine to predict the drug response of each individual. The accumulation of various types of drug informatics and multi-omics data facilitates the development of efficient models for drug response prediction. However, the selection of high-quality data sources and the design of suitable methods remain a challenge.

METHODS

In this paper, we design NeRD, a multidimensional data integration model based on the PRISM drug response database, to predict the cellular response of drugs. Four feature extractors, including drug structure extractor (DSE), molecular fingerprint extractor (MFE), miRNA expression extractor (mEE), and copy number extractor (CNE), are designed for different types and dimensions of data. A fully connected network is used to fuse all features and make predictions.

RESULTS

Experimental results demonstrate the effective integration of the global and local structural features of drugs, as well as the features of cell lines from different omics data. For all metrics tested on the PRISM database, NeRD surpassed previous approaches. We also verified that NeRD has strong reliability in the prediction results of new samples. Moreover, unlike other algorithms, when the amount of training data was reduced, NeRD maintained stable performance.

CONCLUSIONS

NeRD's feature fusion provides a new idea for drug response prediction, which is of great significance for precise cancer treatment.

Targeting HSP90 as a Novel Therapy for Cancer: Mechanistic Insights and Translational Relevance

Heat shock protein (HSP90), a highly conserved molecular chaperon, is indispensable for the maturation of newly synthesized poly-peptides and provides a shelter for the turnover of misfolded or denatured proteins. In cancers, the client proteins of HSP90 extend to the entire process of oncogenesis that are associated with all hallmarks of cancer. Accumulating evidence has demonstrated that the client proteins are guided for proteasomal degradation when their complexes with HSP90 are disrupted. Accordingly, HSP90 and its co-chaperones have emerged as viable targets for the development of cancer therapeutics. Consequently, a number of natural products and their analogs targeting HSP90 have been identified. They have shown a strong inhibitory effect on various cancer types through different mechanisms. The inhibitors act by directly binding to either HSP90 or its co-chaperones/client proteins. Several HSP90 inhibitors—such as geldanamycin and its derivatives, gamitrinib and shepherdin—are under clinical evaluation with promising results. Here, we review the subcellular localization of HSP90, its corresponding mechanism of action in the malignant phenotypes, and the recent progress on the development of HSP90 inhibitors. Hopefully, this comprehensive review will shed light on the translational potential of HSP90 inhibitors as novel cancer therapeutics.

Heat shock proteins: Biological functions, pathological roles, and therapeutic opportunities

The heat shock proteins (HSPs) are ubiquitous and conserved protein families in both prokaryotic and eukaryotic organisms, and they maintain cellular proteostasis and protect cells from stresses. HSP protein families are classified based on their molecular weights, mainly including large HSPs, HSP90, HSP70, HSP60, HSP40, and small HSPs. They function as molecular chaperons in cells and work as an integrated network, participating in the folding of newly synthesized polypeptides, refolding metastable proteins, protein complex assembly, dissociating protein aggregate dissociation, and the degradation of misfolded proteins. In addition to their chaperone functions, they also play important roles in cell signaling transduction, cell cycle, and apoptosis regulation. Therefore, malfunction of HSPs is related with many diseases, including cancers, neurodegeneration, and other diseases. In this review, we describe the current understandings about the molecular mechanisms of the major HSP families including HSP90/HSP70/HSP60/HSP110 and small HSPs, how the HSPs keep the protein proteostasis and response to stresses, and we also discuss their roles in diseases and the recent exploration of HSP related therapy and diagnosis to modulate diseases. These research advances offer new prospects of HSPs as potential targets for therapeutic intervention.

Role of collagen regulators in cancer treatment: A comprehensive review

Abstract:

Collagen is the most important structural protein and also a main component of extra-cellular matrix (ECM). It plays a role in tumor progression. Collagen can be regulated by altering it’s biosynthesis pathway through various signaling pathways, receptors and genes. Activity of cancer cells can also be regulated by other ECM components like metalloproteinases, hyaluronic acid, fibronectin and so on. Hypoxia is also one of the condition which leads to cancer progression by stimulating the expression of procollagen lysine as a collagen crosslinker, which increases the size of collagen fibres promoting cancer spread. The collagen content in cancerous cells leads to resistance in chemotherapy. So, to reduce this resistance, some of the collagen regulating therapies are introduced, which include inhibiting its biosynthesis, disturbing cancer cell signaling pathway, mediating ECM components and directly utilizing collagenase. This study is an effort to compile the strategies reported to control the collagen level and different collagen inhibitors reported so far. More research is needed in this area, growing understandings of collagen’s structural features and its role in cancer progression will aid in the advancement of newer chemotherapies.

Combined PARP and HSP90 inhibition: preclinical and Phase 1 evaluation in patients with advanced solid tumours

PURPOSE

PARP inhibitor resistance may be overcome by combinatorial strategies with agents that disrupt homologous recombination repair (HRR). Multiple HRR pathway components are HSP90 clients, so that HSP90 inhibition leads to abrogation of HRR and sensitisation to PARP inhibition. We performed in vivo preclinical studies of the HSP90 inhibitor onalespib with olaparib and conducted a Phase 1 combination study.

PATIENTS AND METHODS

Tolerability and efficacy studies were performed in patient-derived xenograft(PDX) models of ovarian cancer. Clinical safety, tolerability, steady-state pharmacokinetics and preliminary efficacy of olaparib and onalespib were evaluated using a standard 3 + 3 dose-escalation design.

RESULTS

Olaparib/onalespib exhibited anti-tumour activity against BRCA1-mutated PDX models with acquired PARPi resistance and PDX models with RB-pathway alterations(CDKN2A loss and CCNE1 overexpression). Phase 1 evaluation revealed that dose levels up to olaparib 300 mg/onalespib 40 mg and olaparib 200 mg/onalespib 80 mg were safe without dose-limiting toxicities. Coadministration of olaparib and onalespib did not appear to affect the steady-state pharmacokinetics of either agent. There were no objective responses, but disease stabilisation ≥24 weeks was observed in 7/22 (32%) evaluable patients including patients with BRCA-mutated ovarian cancers and acquired PARPi resistance and patients with tumours harbouring RB-pathway alterations.

CONCLUSIONS

Combining onalespib and olaparib was feasible and demonstrated preliminary evidence of anti-tumour activity.

Inhibition of the HIF-1 Survival Pathway as a Strategy to Augment Photodynamic Therapy Efficacy

Photodynamic therapy (PDT) is a non-to-minimally invasive treatment modality that utilizes photoactivatable drugs called photosensitizers to disrupt tumors with locally photoproduced reactive oxygen species (ROS). Photosensitizer activation by light results in hyperoxidative stress and subsequent tumor cell death, vascular shutdown and hypoxia, and an antitumor immune response. However, sublethally afflicted tumor cells initiate several survival mechanisms that account for decreased PDT efficacy. The hypoxia inducible factor 1 (HIF-1) pathway is one of the most effective cell survival pathways that contributes to cell recovery from PDT-induced damage. Several hundred target genes of the HIF-1 heterodimeric complex collectively mediate processes that are involved in tumor cell survival directly and indirectly (e.g., vascularization, glucose metabolism, proliferation, and metastasis). The broad spectrum of biological ramifications culminating from the activation of HIF-1 target genes reflects the importance of HIF-1 in the context of therapeutic recalcitrance. This chapter elaborates on the involvement of HIF-1 in cancer biology, the hypoxic response mechanisms, and the role of HIF-1 in PDT. An overview of inhibitors that either directly or indirectly impede HIF-1-mediated survival signaling is provided. The inhibitors may be used as pharmacological adjuvants in combination with PDT to augment therapeutic efficacy.

The heat shock response and small molecule regulators

The heat shock response (HSR) is a highly conserved cellular pathway that is responsible for stress relief and the refolding of denatured proteins [1]. When a host cell is exposed to conditions such as heat shock, ischemia, or toxic substances, heat shock factor-1 (HSF-1), a transcription factor, activates the genes that encode for the heat shock proteins (Hsps), which are a family of proteins that work alongside other chaperones to relieve stress and refold proteins that have been denatured (Burdon, 1986) [2]. Along with the refolding of denatured proteins, Hsps facilitate the removal of misfolded proteins by escorting them to degradation pathways, thereby preventing the accumulation of misfolded proteins [3]. Research has indicated that many pathological conditions, such as diabetes, cancer, neuropathy, cardiovascular disease, and aging have a negative impact on HSR function and are commonly associated with misfolded protein aggregation [4,5]. Studies indicate an interplay between mitochondrial homeostasis and HSF-1 levels can impact stress resistance, proteostasis, and malignant cell growth, which further support the role of Hsps in pathological and metabolic functions [6]. On the other hand, Hsp activation by specific small molecules can induce the heat shock response, which can afford neuroprotection and other benefits [7]. This review will focus on the modulation of Hsps and the HSR as therapeutic options to treat these conditions.

TP53 in Biology and Treatment of Osteosarcoma

The TP53 gene is mutated in 50% of human tumors. Oncogenic functions of mutant TP53 maintain tumor cell proliferation and tumor growth also in osteosarcomas. We collected data on TP53 mutations in patients to indicate which are more common and describe their role in in vitro and animal models. We also describe animal models with TP53 dysfunction, which provide a good platform for testing the potential therapeutic approaches. Finally, we have indicated a whole range of pharmacological compounds that modulate the action of p53, stabilize its mutated versions or lead to its degradation, cause silencing or, on the contrary, induce the expression of its functional version in genetic therapy. Although many of the described therapies are at the preclinical testing stage, they offer hope for a change in the approach to osteosarcoma treatment based on TP53 targeting in the future.

Acute and 28-days subacute toxicity studies of Gαq-RGS2 signaling inhibitor

Background

The aim of study was to evaluate the single oral dose and 28 day repeated oral administration toxicity profile of the synthetic compound Gαq-RGS2 signaling inhibitor, (1-(5-chloro-2-hydroxyphenyl)-3-(4-(trifluoromethyl)phenyl)-1 H-1,2,4-triazol-5(4 H)-one) as per OECD guideline 425 (2008a) and 407 (2008b), respectively.

Results

In acute toxicity study, a single oral dose administration of Gαq-RGS2 signaling inhibitor did not show any mortality at doses of 5, 50, 300 and 2000 mg/kg within 24 h and 14 days. The treatment of Gαq-RGS2 signaling inhibitor at dose 10 and 100 mg/kg for 28 days did not show any mortality, significant changes in the increase of body weight, various organ damage markers, hematological parameters, relative organ/body weight ratio and microscopic anatomical texture of essential organs as compared to vehicle and normal control.

Conclusions

A single oral administration of Gαq-RGS2 signaling inhibitor up to dose of 2000 mg/kg in mice and repeated administration of Gαq-RGS2 signaling inhibitor at higher dose 100 mg/kg for 28 days in the rats is safe.

Supplementary Information

The online version contains supplementary material available at 10.1186/s42826-021-00093-1.

HSP90 inhibition downregulates DNA replication and repair genes via E2F1 repression

Mantle cell lymphoma (MCL) is an especially aggressive and highly heterogeneous mature B-cell lymphoma. Heat shock protein 90 (HSP90) is considered an attractive therapeutic target in a variety of cancers, including MCL, but no HSP90 inhibitors have succeeded in the clinical trials to date. Exploring fine mechanisms of HSP90 inhibition in cancer cells may shed light on novel therapeutic strategies. Here, we found that HSP90 knockdown and continuous inhibition with ganetespib inhibited growth of MCL cells in vitro and in vivo. To our surprise, transient exposure over 12 h was almost as efficient as continuous exposure, and treatment with ganetespib for 12 h efficiently inhibited growth and induced G1 cell cycle arrest and apoptosis of MCL cells. Transcriptome analysis complemented by functional studies was performed to define critical MCL signaling pathways that are exceptionally sensitive to HSP90 inhibition and vital to cell fate. Six genes (cell division cycle 6, cell division cycle 45, minichromosome maintenance 4, minichromosome maintenance 7, RecQ-mediated genome instability 2, and DNA primase polypeptide 1) involved in DNA replication and repair were identified as consistently downregulated in three MCL cell lines after transient ganetespib treatment. E2F1, an important transcription factor essential for cell cycle progression, was identified as a ganetespib target mediating transcriptional downregulation of these six genes, and its stability was also demonstrated to be maintained by HSP90. This study identifies E2F1 as a novel client protein of HSP90 that is very sensitive and worthy of targeting and also finds that HSP90 inhibitors may be useful in combination therapies for MCL.

Visualizing Borrelia burgdorferi Infection Using a Small-Molecule Imaging Probe

In vivo diagnostic imaging of bacterial infections is currently reliant on targeting their metabolic pathways, an ineffective method to identify microbial species with low metabolic activity. Here, we establish HS-198 as a small-molecule fluorescent conjugate that selectively targets the highly conserved bacterial protein HtpG (high-temperature protein G), within Borrelia burgdorferi, the bacterium responsible for Lyme disease. We describe the use of HS-198 to target morphologic forms of B. burgdorferi in both the logarithmic growth phase and the metabolically dormant stationary phase as well as in inactivated spirochetes. Furthermore, in a murine infection model, systemically injected HS-198 identified B. burgdorferi as revealed by imaging in postnecropsy tissue sections. These findings demonstrate how small-molecule probes directed at conserved bacterial protein targets can function to identify the microbe using noninvasive imaging and potentially as scaffolds to deliver antimicrobial agents to the pathogen.

Targeting the HSP90-CDC37-kinase chaperone cycle: A promising therapeutic strategy for cancer

Heat shock protein 90 (HSP90) is an indispensable molecular chaperone that facilitates the maturation of numerous oncoproteins in cancer cells, including protein kinases, ribonucleoproteins, steroid hormone receptors, and transcription factors. Although over 30 HSP90 inhibitors have steadily entered clinical trials, further clinical advancement has been restricted by their limited efficacy, inevitable heat shock response, and multiple side-effects, likely induced via an ATP inhibition mechanism. Since both ATP and various co-chaperones play essential roles in the HSP90 chaperone cycle to achieve integrated function, optimal therapeutics require an understanding of the dynamic interactions among HSP90, ATP, and cochaperones. To date, continuous research has promoted the exploration of the cochaperone cell division cycle 37 (CDC37) as a kinase-specific recognizer and has shown that the HSP90-CDC37-kinase complex is particularly relevant in cancers. Indeed, disrupting the HSP90-CDC37-kinase complex, rather than totally blocking the ATP function of HSP90, is emerging as an alternative way to avoid the limitations of current inhibitors. In this review, we first briefly introduce the HSP90-CDC37-kinase cycle and present the currently available approaches for inhibitor development targeting this cycle and provide insights into selective regulation of the kinase clients of HSP90 by more directional ways.

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.

HSP90 identified by a proteomic approach as druggable target to reverse platinum resistance in ovarian cancer

Acquired resistance to platinum (Pt)-based therapies is an urgent unmet need in the management of epithelial ovarian cancer (EOC) patients. Here, we characterized by an unbiased proteomics method three isogenic EOC models of acquired Pt resistance (TOV-112D, OVSAHO, and MDAH-2774). Using this approach, we identified several differentially expressed proteins in Pt-resistant (Pt-res) compared to parental cells and the chaperone HSP90 as a central hub of these protein networks. Accordingly, up-regulation of HSP90 was observed in all Pt-res cells and heat-shock protein 90 alpha isoform knockout resensitizes Pt-res cells to cisplatin (CDDP) treatment. Moreover, pharmacological HSP90 inhibition using two different inhibitors [17-(allylamino)-17-demethoxygeldanamycin (17AAG) and ganetespib] synergizes with CDDP in killing Pt-res cells in all tested models. Mechanistically, genetic or pharmacological HSP90 inhibition plus CDDP -induced apoptosis and increased DNA damage, particularly in Pt-res cells. Importantly, the antitumor activities of HSP90 inhibitors (HSP90i) were confirmed both ex vivo in primary cultures derived from Pt-res EOC patients ascites and in vivo in a xenograft model. Collectively, our data suggest an innovative antitumor strategy, based on Pt compounds plus HSP90i, to rechallenge Pt-res EOC patients that might warrant further clinical evaluation.

A novel histone deacetylase inhibitor MPT0L184 dysregulates cell-cycle checkpoints and initiates unscheduled mitotic signaling

Aberrant alteration of epigenetic information disturbs chromatin structure and gene function, thereby facilitating cancer development. Several drugs targeting histone deacetylases (HDACs), a group of epigenetic enzymes, have been approved for treating hematologic malignancies in the clinic. However, patients who suffer from solid tumors often respond poorly to these drugs. In this study, we report a selective entinostat derivative, MPT0L184, with potent cancer-killing activity in both cell-based and mouse xenograft models. A time-course analysis of cell-cycle progression revealed that MPT0L184 treatment elicited an early onset of mitosis but prevented the division of cells with duplicated chromosomes. We show that MPT0L184 possessed potent inhibitory activity toward HDAC1 and 2, and its HDAC-inhibitory activity was required for initiating premature mitotic signaling. HDAC inhibition by MPT0L184 reduced WEE1 expression at the transcription level. In addition, MPT0L184 treatment also downregulated ATR-mediated CHK1 phosphorylation independent of HDAC inhibition. Furthermore, gastric cancer cells resistant to HDAC inhibitors were vulnerable to MPT0L184. Taken together, our study discovers MPT0L184 as a novel HDAC inhibitor that can trigger premature mitosis and potentially counteract drug resistance of cancers.

BIRC3 and BIRC5: multi-faceted inhibitors in cancer

BACKGROUND

The evasion from apoptosis is a common strategy adopted by most tumors, and inhibitors of apoptosis proteins (IAPs) are among the most studied molecular and therapeutic targets. BIRC3 (cellular IAP2) and BIRC5 (survivin) are two of the eight members of the human IAPs family. This family is characterized by the presence of the baculoviral IAP repeat (BIR) domains, involved in protein-protein interactions. In addition to the BIR domains, IAPs also contain other important domains like the C-terminal ubiquitin-conjugating (UBC) domain, the caspase recruitment (CARD) domain and the C-terminal Ring zinc-finger (RING) domain.

MAIN BODY

BIRC3 and BIRC5 have been characterized in some solid and hematological tumors and are therapeutic targets for the family of drugs called "Smac mimetics". Many evidences point to the pro-survival and antiapoptotic role of BIRC3 in cancer cells, however, not all the data are consistent and the resulting picture is heterogeneous. For instance, BIRC3 genetic inactivation due to deletions or point mutations is consistently associated to shorter progression free survival and poor prognosis in chronic lymphocytic leukemia patients. BIRC3 inactivation has also been associated to chemoimmunotherapy resistance. On the contrary, the progression from low grade gliomas to high grade gliomas is accompanied by BIRC3 expression increase, which bears relevant prognostic consequences. Due to the relationship between BIRC3, MAP3K14 and the non-canonical NF-kB pathway, BIRC3 inactivation bears consequences also on the tumor cells relying on NF-kB pathway to survive. BIRC5, on the contrary, is commonly considered an anti-apoptotic molecule, promoting cell division and tumor progression and it is widely regarded as potential therapeutic target.

CONCLUSIONS

The present manuscript collects and reviews the most recent literature concerning the role played by BIRC3 and BIRC5 in cancer cells, providing useful information for the choice of the best therapeutic targets.

Differential effects of Hsp90 inhibition on corneal cells in vitro and in vivo

The transformation of quiescent keratocytes to activated fibroblasts and myofibroblasts (KFM transformation) largely depends on transforming growth factor beta (TGFβ) signaling. Initiation of the TGFβ signaling cascade results from binding of TGFβ to the labile type I TGFβ receptor (TGFβRI), which is stabilized by the 90 kDa heat shock protein (Hsp90). Since myofibroblast persistence within the corneal stroma can result in stromal haze and corneal fibrosis in patients undergoing keratorefractive therapy, modulation of TGFβ signaling through Hsp90 inhibition would represent a novel approach to prevent myofibroblast persistence. In vitro, rabbit corneal fibroblasts (RCFs) or stratified immortalized human corneal epithelial cells (hTCEpi) were treated with a Hsp90 inhibitor (17AAG) in the presence/absence of TGFβ1. RCFs were cultured either on tissue culture plastic, anisotropically patterned substrates, and hydrogels of varying stiffness. Cellular responses to both cytoactive and variable substrates were assessed by morphologic changes to the cells, and alterations in expression patterns of key keratocyte and myofibroblast proteins using PCR, Western blotting and immunocytochemistry. Transepithelial electrical resistance (TEER) measurements were performed to establish epithelial barrier integrity. In vivo, the corneas of New Zealand White rabbits were wounded by phototherapeutic keratectomy (PTK) and treated with 17AAG (3× or 6× daily) either immediately or 7 days after wounding for 28 days. Rabbits underwent clinical ophthalmic examinations, SPOTS scoring and advanced imaging on days 0, 1, 3, 7, 10, 14, 21 and 28. On day 28, rabbits were euthanized and histopathology/immunohistochemistry was performed. In vitro data demonstrated that 17AAG inhibited KFM transformation with the de-differentiation of spindle shaped myofibroblasts to dendritic keratocyte-like cells accompanied by significant upregulation of corneal crystallins and suppression of myofibroblast markers regardless of TGFβ1 treatment. RCFs cultured on soft hydrogels or patterned substrates exhibited elevated expression of α-smooth muscle actin (αSMA) in the presence of 17AAG. Treatment of hTCEpi cells disrupted zonula occludens 1 (ZO-1) adherens junction formation. In vivo, there were no differences detected in nearly all clinical parameters assessed between treatment groups. However, rabbits treated with 17AAG developed greater stromal haze formation compared with controls, irrespective of frequency of administration. Lastly, there was increased αSMA positive myofibroblasts in the stroma of 17AAG treated animals when compared with controls. Hsp90 inhibition promoted reversion of the myofibroblast to keratocyte phenotype, although this only occurred on rigid substrates. By contrast, in vivo Hsp90 inhibition was detrimental to corneal wound healing likely due to impairment in corneal epithelial closure and barrier function restoration. Collectively, our data demonstrated a strong interplay in vitro between biophysical cues and soluble signaling molecules in determining corneal stromal cell phenotype.

Modulation of protein fate decision by small molecules: targeting molecular chaperone machinery

Modulation of protein fate decision and protein homeostasis plays a significant role in altering the protein level, which acts as an orientation to develop drugs with new mechanisms. The molecular chaperones exert significant biological functions on modulation of protein fate decision and protein homeostasis under constantly changing environmental conditions through extensive protein–protein interactions (PPIs) with their client proteins. With the help of molecular chaperone machinery, the processes of protein folding, trafficking, quality control and degradation of client proteins could be arranged properly. The core members of molecular chaperones, including heat shock proteins (HSPs) family and their co-chaperones, are emerging as potential drug targets since they are involved in numerous disease conditions. Development of small molecule modulators targeting not only chaperones themselves but also the PPIs among chaperones, co-chaperones and clients is attracting more and more attention. These modulators are widely used as chemical tools to study chaperone networks as well as potential drug candidates for a broader set of diseases. Here, we reviewed the key checkpoints of molecular chaperone machinery HSPs as well as their co-chaperones to discuss the small molecules targeting on them for modulation of protein fate decision.

Fluoropyrimidin-2,4-dihydroxy-5-isopropylbenzamides as antitumor agents against CRC and NSCLC cancer cells

A major cause of failure of therapy in patients with non-small cell lung cancer (NSCLC) is development of acquired drug resistance leading to tumor recurrence and disease progression. In addition to the development of new generations of epidermal growth factor receptor-tyrosine kinase inhibitors (EGFR-TKIs), different molecular targets may provide opportunities to improve the therapeutic outcomes. In this study, we utilized the core structure 5-fluorouracil (5-FU) or tegafur, a 5-FU prodrug combined through different linkers with resorcinol to generate a series of fluoropyrimidin-2,4-dihydroxy-5-isopropylbenzamides which inhibit potent Heat Shock Protein 90 (HSP90). These compounds were found to show significant antiproliferative activity in colorectal cancer (CRC) HCT116 and NSCLC A549, H460, and H1975 (EGFR L858R/T790 M double mutation) cells. Compound 12c, developed by molecular docking analysis and enzymatic assays exhibits promising inhibitory activity of HSP90. This compound, 12c shows the most potent HSP90 inhibitory activity with an IC₅₀ value of 27.8 ± 4.4 nM, superior to that of reference compounds AUY-922 (Luminespib) and BIIB021 whose IC₅₀ values are 43.0 ± 0.9 nM and 56.8 ± 4.0 nM respectively. This strong HSP90 inhibitory activity of 12c leads to rapid degradation of client proteins EGFR and Akt in NSCLC cells. In addition, 12c induces significant accumulation of a sub-G1 phase population in parallel with apoptosis by showing activated caspase-3, -8 and -9 and PARP induction. These results provide a new strategy for development of novel HSP90 inhibitors for cancer treatment.

Hepatic Microwave Ablation-Induced Tumor Destruction and Animal End Point Survival Can Be Improved by Suppression of Heat Shock Protein 90

OBJECTIVES

To investigate the effect of heat shock protein 90 (HSP90) modulation on tumor necrosis, apoptosis, tumor growth delay, and end point survival by combining microwave ablation (MWA) with an HSP90 inhibitor in a nude mouse model.

METHODS

This study was approved by the Ethics Committee. Forty mice with HepG2 subcutaneous xenograft tumors (10 ± 1 mm) were randomized into 4 groups: (1) no treatment, (2) MWA only, (3) the HSP90 inhibitor ganetespib only, and (4) ganetespib combined with MWA. Tumors were harvested 24 hours after treatment, and gross coagulation diameters were measured. The effect of ganetespib on HSP90 and caspase 3 expression in the periablational rim was assessed. Another 40 mice with the same tumors and groupings were observed after treatment. Tumor growth curve and Kaplan-Meier survival analyses were performed with a tumor diameter of 2.2 cm and 40 days of survival as the defined survival end points.

RESULTS

Combination treatment significantly increased the coagulation size compared to tumors treated with MWA or ganetespib alone (P < 0.05). The combination of MWA and ganetespib decreased HSP90 expression and increased cleaved caspase 3 expression 24 hours after treatment. Compared with MWA or ganetespib only, combination treatment could lengthen the end point survival and reduce the tumor growth rate.

CONCLUSIONS

Modulation of HSP production can improve MWA-induced tumor apoptosis and destruction, reduce residual tumor growth rates, and prolong end point survival.

Discovery of novel heat shock protein (Hsp90) inhibitors based on luminespib with potent antitumor activity

A series of isosteric surrogates of the 4-phenyl group in luminespib were investigated as new scaffolds of the Hsp90 inhibitor for the discovery of novel antitumor agents. Among the synthesized surrogates of isoxazole and pyrazole, compounds 4a, 5e and 12b exhibited potent Hsp90 inhibition in ATPase activity and Her2 degradation assays and significant antitumor activity in A2780 and HCT116 cell lines. Animal studies indicated that compared to luminespib, their activities were superior in A2780 or NCI-H1975 tumor xenograft models. A molecular modeling study demonstrated that compound 4a could fit nicely into the N-terminal ATP binding pocket.

A Chemical Biology Approach to the Chaperome in Cancer-HSP90 and Beyond

Cancer is often associated with alterations in the chaperome, a collection of chaperones, cochaperones, and other cofactors. Changes in the expression levels of components of the chaperome, in the interaction strength among chaperome components, alterations in chaperome constituency, and in the cellular location of chaperome members, are all hallmarks of cancer. Here we aim to provide an overview on how chemical biology has played a role in deciphering such complexity in the biology of the chaperome in cancer and in other diseases. The focus here is narrow and on pathologic changes in the chaperome executed by enhancing the interaction strength between components of distinct chaperome pathways, specifically between those of HSP90 and HSP70 pathways. We will review chemical tools and chemical probe-based assays, with a focus on HSP90. We will discuss how kinetic binding, not classical equilibrium binding, is most appropriate in the development of drugs and probes for the chaperome in disease. We will then present our view on how chaperome inhibitors may become potential drugs and diagnostics in cancer.

Heat shock proteins in thyroid malignancies: Potential therapeutic targets for poorly-differentiated and anaplastic tumours?

Thyroid cancer is the most common endocrine malignancy, with well-differentiated subtypes characterized by an excellent prognosis due to their optimal sensitivity to standard therapies whereas poorly differentiated and anaplastic tumours by chemo/radio-resistance and unfavourable outcome. Heat Shock Proteins (HSPs) are molecular chaperones overexpressed in thyroid malignancies and involved in crucial functions responsible for thyroid carcinogenesis, as protection from apoptosis, drug resistance and cell migration. Thus, HSPs inhibitors have been proposed as novel therapeutic agents in thyroid cancer to revert molecular mechanisms of tumour progression. In this review, we report an overview on the biological role of HSPs, and specifically HSP90s, in thyroid cancer and their potential involvement as biomarkers. We discuss the rationale to evaluate HSPs inhibitors as innovative anticancer agents in specific subtypes of thyroid cancer characterized by poor response to therapies with the objective to target single family chaperones to reduce, simultaneously, the expression/stability of multiple client proteins.

Natural heat shock protein 90 inhibitors in cancer and inflammation

Heat shock protein (HSP)90 is the most abundant HSPs, which are chaperone molecules whose major roles are cell protection and maintenance by means of aiding the folding, the stabilization and the remodeling of a wide range of proteins. A few hundreds of proteins depend on HSP90 chaperone activity, including kinases and transcriptional factors that play essential roles in cancer and inflammation, so that HSP90-targeted therapies have been considered as a potential strategy for the treatment of cancer and inflammatory-associated diseases. HSP90 inhibition by natural, semi-synthetic and synthetic compounds have yield promising results in pre-clinical studies and clinical trials for different types of cancers and inflammation. Natural products are a huge source of biologically active compounds widely used in drug development due to the great diversity of their metabolites which are capable to modulate several protein functions. HSP90 inhibitors have been isolated from bacteria, fungi and vegetal species. These natural compounds have a noteworthy ability to modulate HSP90 activity as well as serve as scaffolds for the development of novel synthetic or semi-synthetic inhibitors. Over a hundred clinical trials have evaluated the effect of HSP90 inhibitors as adjuvant treatment against different types of tumors and, currently, new studies are being developed to gain sight on novel promising and more effective approaches for cancer treatment. In this review, we present the naturally occurring HSP90 inhibitors and analogues, discussing their anti-cancer and anti-inflammatory effects.

HSP90 Inhibitor Ganetespib (STA-9090) Inhibits Tumor Growth in c-Myc-Dependent Esophageal Squamous Cell Carcinoma

PURPOSE

Currently, the paucity of classical effective pharmacological drugs to treat esophageal squamous cell carcinoma (ESCC) is a major problem. The c-Myc (MYC) protein is a promising target as it is overexpressed in ESCC. MYC is a sensitive client protein of the heat shock protein 90 (HSP90) and, therefore, targeting the HSP90-MYC axis by inhibition of HSP90 is a potential therapeutic strategy for ESCC. Here, we evaluated the clinical application value of the HSP90 inhibitor (Ganetespib, STA-9090) as an anti-cancer agent for MYC-positive ESCC.

MATERIALS AND METHODS

We first analyzed ESCC tissue microarrays and clinical tissue samples to determine MYC expression. The relationship between MYC and HSP90 was analyzed by co-immunoprecipitation assays and immunofluorescence. In in vitro cell models, cell growth was analyzed using the CCK-8 kit, and MYC protein expression was analyzed by Western blot. The in vivo antitumor activity of STA-9090 was assessed in two xenograft animal models.

RESULTS

We demonstrated that MYC-overexpressing ESCC cells were highly sensitive to STA-9090 treatment through suppressing ESCC cell proliferation, cell cycle progression and survival. Moreover, STA-9090 treatment decreased MYC expression, reducing the half-life of the MYC protein. We further established two xenograft mouse models using ESCC cells and clinical ESCC samples to validate the effectiveness of STA-9090 in vivo. In both xenograft models, STA-9090 substantially inhibited the growth of MYC-positive ESCC tumors in vivo. In contrast, STA-9090 treatment demonstrated no beneficial effects in mice with low-MYC expressing ESCC tumors.

CONCLUSION

In conclusion, our data support that the HSP90 inhibitor, STA-9090, suppresses the expression of the MYC protein and interferes with HSP90-MYC protein-protein interaction. This, in turn, leads to inhibition of ESCC cell proliferation and promotion of apoptosis in ESCC cells in vitro and reduction of ESCC tumors in vivo. We propose, based on our findings, that STA-9090 is a potential novel therapeutic target for MYC-positive ESCC.

Randomized Phase III Study of Ganetespib, a Heat Shock Protein 90 Inhibitor, With Docetaxel Versus Docetaxel in Advanced Non-Small-Cell Lung Cancer (GALAXY-2)

PURPOSE

Ganetespib, a highly potent heat shock protein 90 inhibitor, blocks multiple oncogenic pathways, resulting in antitumor activity. We evaluated the combination of ganetespib and docetaxel for second-line therapy of patients with advanced adenocarcinoma of the lung.

PATIENTS AND METHODS

In this international phase III trial, patients with stage IIIB or IV adenocarcinoma diagnosed > 6 months before study entry and 1 prior systemic therapy were randomly assigned (1:1) to ganetespib 150 mg/m² on days 1 and 15 with docetaxel 75 mg/m² on day 1 of a 21-day cycle or to docetaxel alone. The primary end point was overall survival (OS).

RESULTS

Of 677 enrolled patients, 335 were randomly assigned to ganetespib and docetaxel and 337 were assigned to docetaxel. The trial was stopped early as a result of futility at a planned interim analysis. The median OS time was 10.9 months (95% CI, 9.0 to 12.3 months) in the ganetespib and docetaxel arm compared with 10.5 months (95% CI, 8.6 to 12.2 months) in docetaxel arm (hazard ratio [HR], 1.11; 95% CI, 0.899 to 1.372; P = .329). Median progression-free survival was 4.2 months in the ganetespib and docetaxel arm and 4.3 months in the docetaxel arm (HR, 1.16; 95% CI, 0.96 to 1.403; P = .119). The addition of ganetespib did not improve outcomes compared with docetaxel alone for any secondary end point, including survival in the elevated lactate dehydrogenase or EGFR and ALK wild-type populations. The most common grade 3 or 4 adverse event in both arms was neutropenia (30.9% with ganetespib and docetaxel v 25% with docetaxel).

CONCLUSION

The addition of ganetespib to docetaxel did not result in improved survival for salvage therapy of patients with advanced-stage lung adenocarcinoma.

Tumor-Targeted Drug Conjugates as an Emerging Novel Therapeutic Approach in Small Cell Lung Cancer (SCLC)

There are few effective therapies for small cell lung cancer (SCLC), a highly aggressive disease representing 15% of total lung cancers. With median survival <2 years, SCLC is one of the most lethal cancers. At present, chemotherapies and radiation therapy are commonly used for SCLC management. Few protein-targeted therapies have shown efficacy in improving overall survival; immune checkpoint inhibitors (ICIs) are promising agents, but many SCLC tumors do not express ICI targets such as PD-L1. This article presents an alternative approach to the treatment of SCLC: the use of drug conjugates, where a targeting moiety concentrates otherwise toxic agents in the vicinity of tumors, maximizing the differential between tumor killing and the cytotoxicity of normal tissues. Several tumor-targeted drug conjugate delivery systems exist and are currently being actively tested in the setting of SCLC. These include antibody-drug conjugates (ADCs), radioimmunoconjugates (RICs), small molecule-drug conjugates (SMDCs), and polymer-drug conjugates (PDCs). We summarize the basis of action for these targeting compounds, discussing principles of construction and providing examples of effective versus ineffective compounds, as established by preclinical and clinical testing. Such agents may offer new therapeutic options for the clinical management of this challenging disease in the future.

Hsp90 inhibitors enhance the antitumoral effect of osimertinib in parental and osimertinib-resistant non-small cell lung cancer cell lines

Background

Osimertinib improve therapy for non-small cell lung cancer (NSCLC). However, invariable acquired resistance appears.

Methods

MTT assay was used to analyze cell viability. Protein expression and activation was detected by Western blotting. In addition, the effects of heat shock protein 90 (Hsp90) inhibitors and osimertinib were studied in colony formation assays.

Results

Our laboratory generated osimertinib resistant cell lines from PC9 cell line and overexpression or activation of several proteins was detected. Hsp90 inhibitors, ganetespib and luminespib, inhibited cell viability and colony formation in H1975, PC9 and PC9-derived osimertinib-resistant cell lines and combination of these inhibitors with osimertinib achieved to enhance this cell viability and colony formation inhibition. Luminespib downregulated the expression of the several proteins involved in osimertinib-resistance and the combination of this compound plus osimertinib caused an important decrease of expression of several of these proteins, such as Stat3, Yap, Akt, EGFR and Met. Osimertinib activated the phosphorylation of several membrane receptors and downstream molecules that was partially inhibited by luminespib. In addition, a lung cancer patient with an EGFR eon 20 mutation had a partial radiographic response to ganetespib.

Conclusions

Hsp90 inhibitors and osimertinib exhibits a good efficiency to inhibit cell viability, colony formation and inhibits expression and activation of proteins involved in osimertinib-resistance and may represent an effective strategy for NSCLC with intrinsic resistance to osimertinib inhibition.