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Lytic induction therapy was devised to selectively combat malignancies associated with Epstein–Barr virus (EBV) by triggering viral reactivation from latency. At present, the major challenges of lytic induction therapy are to maximize reactivating efficiencies and meanwhile minimize infectious virion production. C210, a novel curcumin derivative with potent Hsp90 inhibitory activity, was explored for EBV-reactivating and virion-producing effects in EBV-positive nasopharyngeal carcinoma (NPC) and gastric carcinoma (GC) cell lines. And the molecular mechanisms underlying these effects were determined. Follow C210 treatment, EBV lytic RNAs and proteins were upregulated, but infectious virions were not produced. Knockdown of heat shock protein 90 (Hsp90) induced expression of lytic RNAs and proteins, and diminished C210-driven EBV lytic induction. Pretreatment with an X box binding protein 1 (XBP1) inhibitor reduced C210-induced EBV lytic RNA. Furthermore, we demonstrated that C210 inhibited the binding of Hsp90 with its clients, signal transducer and activator of transcription 3 (STAT3) and xeroderma pigmentosum group B-complementing protein (XPB), which subsequently promoted their proteasomal degradation. Degradation of STAT3 by C210 enhanced the EBV-reactivating and anticancer capacity of suberoylanilide hydroxamic acid (SAHA). Depletion of XPB blocked SAHA-induced expression of late viral genes and production of infectious virions. These results elucidate a novel Hsp90 inhibitor targeting EBV lytic phase and extend the research on lytic induction strategy, which may offer reference value in the treatment of EBV-positive malignancies. [ABSTRACT FROM AUTHOR]

Disease progression is a major problem in ovarian cancer. There are very few treatment options for patients with platinum‐resistant ovarian cancer (PROC), and therefore, these patients have a particularly poor prognosis. The aim of the present study was to identify markers for monitoring the response of 123 PROC patients enrolled in the Phase I/II GANNET53 clinical trial, which evaluated the efficacy of Ganetespib in combination with standard chemotherapy versus standard chemotherapy alone. In total, 474 blood samples were collected, comprising baseline samples taken before the first administration of the study drugs and serial samples taken during treatment until further disease progression (PD). After microfluidic enrichment, 27 gene transcripts were analyzed using quantitative polymerase chain reaction and their utility for disease monitoring was evaluated. At baseline, ERCC1 was associated with an increased risk of PD (hazard ratio [HR] 1.75, 95% confidence interval [CI]: 1.20–2.55; p = 0.005), while baseline CDH1 and ESR1 may have a risk‐reducing effect (CDH1 HR 0.66, 95% CI: 0.46–0.96; p = 0.024; ESR1 HR 0.58, 95% CI: 0.39–0.86; p = 0.002). ERCC1 was observed significantly more often (72.7% vs. 53.9%; p = 0.032) and ESR1 significantly less frequently (59.1% vs. 78.3%; p = 0.018) in blood samples taken at radiologically confirmed PD than at controlled disease. At any time during treatment, ERCC1‐presence and ESR1‐absence were associated with short PFS and with higher odds of PD within 6 months (odds ratio 12.77, 95% CI: 4.08–39.97; p < 0.001). Our study demonstrates the clinical relevance of ESR1 and ERCC1 and may encourage the analysis of liquid biopsy samples for the management of PROC patients. [ABSTRACT FROM AUTHOR]

Background/Aim: Breast cancer is the most predominant type of cancer affecting women worldwide and the current therapeutic treatment for breast cancer patients is not adequately effective. This study aimed to investigate the mechanism of 17-AAG, a heat shock protein (HSP90) inhibitor, as a treatment for inducing breast cancer cell apoptosis. Materials and Methods: The pharmacology network was employed to examine the correlation of 17-AAG with the gene expression profiles of breast cancer, obtained by Gene Expression Profiling Interactive Analysis (GEPIA). MTT and flow cytometry were utilized to investigate cell proliferation and cell apoptosis, respectively. Dichlorodihydro-fluorescein diacetate (DCFH-DA) assay and western blot analysis were employed to examine the correlation between cellular oxidant levels and protein expression. Immunofluorescence staining was utilized to confirm the protein localization and assess DNA damage. Results: The pharmacological network analysis revealed that HSP90 serves as the common target connecting 17-AAG and breast cancer genes. Treatment with 17-AAG significantly increased cell apoptosis. Moreover, the treatment resulted in upregulation of cellular oxidant levels and PERK/eIF2α expression. In line with these, protein localization after treatment revealed an increase in DNA damage, correlating with higher ER stress levels. Furthermore, GEPIA demonstrated that PERK and eIF2α expression were significantly higher in breast invasive carcinoma compared to other tumor types. Conclusion: HSP90 emerges as a potential target for inducing apoptosis in breast cancer cells by disrupting protein homeostasis in the endoplasmic reticulum, possibly through PERK/eIF2α up-regulation. 17- AAG, an HSP90 inhibitor, may therefore potentially hold an alternative therapeutic strategy for breast cancer treatment. [ABSTRACT FROM AUTHOR]

Abstract Heat shock protein 90 (Hsp90), a molecular chaperone, contributes to the preservation of folding, structure, stability, and function proteins. In this study, novel compounds comprising isoxazole structure were designed, synthesized and their potential ability as Hsp90 inhibitors was validated through docking studies. The active site-based compounds were prepared through a multi-step synthesis process and their chemical structures were characterized employing FT-IR, NMR, and mass spectrometry analysis. Cytotoxic and Hsp90 inhibition activities of synthesized compounds were assessed by MTT assay and ELISA kit, respectively. Based on the obtained results, compound 5 exhibited the highest cytotoxicity (IC50; 14 µM) against cancer cells and reduced Hsp90 expression from 5.54 ng/mL in untreated (normal cells) to 1.56 ng/mL in cancer cells. Moreover, molecular dynamics (MD) simulation results indicated its high affinity to target protein and approved its excellent stability which is essential for exerting an inhibitory effect on cancer cell proliferation.

Abstract Lytic induction therapy was devised to selectively combat malignancies associated with Epstein–Barr virus (EBV) by triggering viral reactivation from latency. At present, the major challenges of lytic induction therapy are to maximize reactivating efficiencies and meanwhile minimize infectious virion production. C210, a novel curcumin derivative with potent Hsp90 inhibitory activity, was explored for EBV-reactivating and virion-producing effects in EBV-positive nasopharyngeal carcinoma (NPC) and gastric carcinoma (GC) cell lines. And the molecular mechanisms underlying these effects were determined. Follow C210 treatment, EBV lytic RNAs and proteins were upregulated, but infectious virions were not produced. Knockdown of heat shock protein 90 (Hsp90) induced expression of lytic RNAs and proteins, and diminished C210-driven EBV lytic induction. Pretreatment with an X box binding protein 1 (XBP1) inhibitor reduced C210-induced EBV lytic RNA. Furthermore, we demonstrated that C210 inhibited the binding of Hsp90 with its clients, signal transducer and activator of transcription 3 (STAT3) and xeroderma pigmentosum group B-complementing protein (XPB), which subsequently promoted their proteasomal degradation. Degradation of STAT3 by C210 enhanced the EBV-reactivating and anticancer capacity of suberoylanilide hydroxamic acid (SAHA). Depletion of XPB blocked SAHA-induced expression of late viral genes and production of infectious virions. These results elucidate a novel Hsp90 inhibitor targeting EBV lytic phase and extend the research on lytic induction strategy, which may offer reference value in the treatment of EBV-positive malignancies.

Background: Heat shock protein 90 (HSP90) is a molecular chaperone required for stabilization of client proteins over-activated in triple-negative breast cancer (TNBC). Over-expression of HSP90 client proteins has been implicated in paclitaxel resistance. Onalespib (AT13387) is a potent inhibitor of HSP90 that could improve paclitaxel efficacy when administered in combination. Design: This phase Ib trial administered onalespib with paclitaxel in patients with advanced TNBC to assess safety and establish a recommended phase II dose (RP2D). Objectives: The primary objectives were determining the dose-limiting toxicities and maximum tolerated dose of combination therapy. Secondary objectives included pharmacokinetic (PK) analysis and determination of overall response rate (ORR), duration of response (DOR), and progression-free survival (PFS). Methods: Patients with advanced TNBC were treated with standard dose intravenous paclitaxel in combination with intravenous onalespib at doses ranging from 120 to 260 mg/m2 administered on days 1, 8, and 15 of a 28-day cycle using a standard 3 + 3 design. A total of 15 patients were enrolled to dose expansion cohort at RP2D to confirm safety profile. Results: Thirty-one patients were enrolled in the study, of which over 90% had received prior taxane therapy. Paclitaxel was given for metastatic disease in 23% of patients. Adverse events (AEs) included anemia (grade 3: 20%), lymphopenia (grade 3: 17%), and neutropenia (grade 3: 33%, grade 4: 4%). The most frequent grade ⩾3 non-hematologic AE was diarrhea (7%). The established RP2D was 260 mg/m2 onalespib when given with paclitaxel at 80 mg/m2. PK analysis revealed a modest drug interaction profile for onalespib in the combination regimen. ORR was 20%. Three patients achieved complete responses, all of whom had received prior taxane therapy. Median DOR was 5.6 months; median PFS was 2.9 months. Conclusion: Combination treatment with onalespib and paclitaxel had an acceptable toxicity profile and RP2D was determined to be 260 mg/m2 of onalespib. Combination therapy showed antitumor activity in patients with advanced TNBC. Trial registration: Onalespib and paclitaxel in treating patients with advanced TNBC https://clinicaltrials.gov/ct2/show/NCT02474173. Plain language summary: Phase 1b study of HSP90 inhibitor called onalespib in combination with paclitaxel in patients with advanced triple-negative breast cancer This Phase 1b study demonstrated that treatment with a combination of onalespib and paclitaxel was reasonably well tolerated by most patients. Onalespib at 260 mg/m2 given intravenously on days 1, 8 and 15 on 28-day cycles in combination with standard dose and schedule of paclitaxel was established as the recommended phase 2 dose for further clinical development. Despite minor drug-drug interactions between these 2 agents, onalespib did not alter paclitaxel exposure and paclitaxel did not affect exposure to onalespib. While onalespib with paclitaxel combination therapy did not yield durable objective responses or prolonged progression-free survival, there were several patients with long-lasting benefit from this combination including patients who previously experienced progression on taxane therapy. [ABSTRACT FROM AUTHOR]

The Trimethoxyphenyl (TMP) group serves as a pharmacophore in numerous potent agents exhibiting diverse bioactivity effects. This moiety is prominently present in the molecular structures of various research studies, demonstrating remarkable multi-activity or specific targeting, surpassing the activity of other derivatives at comparable concentrations. The compounds containing the TMP group have displayed notable anti-cancer effects by effectively inhibiting tubulin, heat shock protein 90 (Hsp90), thioredoxin reductase (TrxR), histone lysine-specific demethylase 1 (HLSD1), activin receptor-like kinase-2 (ALK2), P-glycoprotein (P-gp), and platelet-derived growth factor receptor β. Furthermore, select TMP-bearing compounds have shown promising anti-fungal and anti-bacterial properties, including activities against Helicobacter pylori and Mycobacterium tuberculosis. Additionally, there have been reports on the antiviral activity of TMP-based compounds, which hold potential against viruses such as the acquired immunodeficiency syndrome (AIDS) virus, hepatitis C virus, and influenza virus. Compounds containing the TMP pharmacophore have also demonstrated significant efficacy against Leishmania, Malaria, and Trypanosoma, indicating their potential as anti-parasitic agents. Furthermore, these compounds have been associated with anti-inflammatory, anti-Alzheimer, anti-depressant, and anti-migraine properties, thereby expanding their therapeutic scope. This paper presents a comprehensive and categorized review of these diverse properties of TMP-bearing compounds, shedding light on their potential as valuable agents across a wide range of biomedical applications. [ABSTRACT FROM AUTHOR]

Constant efforts are being made to develop methods for improving cancer immunotherapy, including cytokine-induced killer (CIK) cell therapy. Numerous heat shock protein (HSP) 90 inhibitors have been assessed for antitumor efficacy in preclinical and clinical trials, highlighting their individual prospects for targeted cancer therapy. Therefore, we tested the compatibility of CIK cells with HSP90 inhibitors using Burkitt's lymphoma (BL) cells. Our analysis revealed that CIK cytotoxicity in BL cells was augmented in combination with independent HSP90 inhibitors 17-DMAG (17-dimethylaminoethylamino-17-demethoxygeldanamycin) and ganetespib. Interestingly, CIK cell cytotoxicity did not diminish after blocking with NKG2D (natural killer group 2, member D), which is a prerequisite for their activation. Subsequent analyses revealed that the increased expression of Fas on the surface of BL cells, which induces caspase 3/7-dependent apoptosis, may account for this effect. Thus, we provide evidence that CIK cells, either alone or in combination with HSP90 inhibitors, target BL cells via the Fas–FasL axis rather than the NKG2D pathway. In the context of clinical relevance, we also found that high expression of HSP90 family genes (HSP90AA1, HSP90AB1, and HSP90B1) was significantly associated with the reduced overall survival of BL patients. In addition to HSP90, genes belonging to the Hsp40, Hsp70, and Hsp110 families have also been found to be clinically significant for BL survival. Taken together, the combinatorial therapy of CIK cells with HSP90 inhibitors has the potential to provide clinical benefits to patients with BL. [ABSTRACT FROM AUTHOR]

Despite several treatment options for blood cancer, mortality remains high due to relapse and the disease's aggressive nature. Elevated levels of HSP90, a molecular chaperone essential for protein folding, are associated with poor prognosis in leukemia and lymphoma. HSP90 as a target for chemotherapy has been met with limited success due to toxicity and induction of heat shock. This study tested the activity of an HSP90 inhibitor, SP11, against leukemic cells, mouse lymphoma allograft, and xenograft models. SP11 induced cytotoxicity in vitro in leukemic cell lines and induced cell death via apoptosis, with minimal effect on normal cells. SP11 induced cell death by altering the status of HSP90 client proteins both in vitro and in vivo. SP11 reduced the tumor burden in allograft and xenograft mouse models without apparent toxicity. The half-life of SP11 in the plasma was approximately 2 h. SP11 binding was observed at both the N-terminal and C-terminal domains of HSP90. C-terminal binding was more potent than N-terminal binding of HSP90 in silico and in vitro using isothermal calorimetry. SP11 bioavailability and minimal toxicity in vivo make it a potential candidate to be developed as a novel anticancer agent. [ABSTRACT FROM AUTHOR]

Hsp90 is a molecular chaperone involved in the refolding and activation of numerous protein substrates referred to as clients. While the molecular determinants of Hsp90 client specificity are poorly understood and limited to a handful of client proteins, strong clients are thought to be destabilized and conformationally extended. Here, we measured the phosphotransferase activity of 3929 variants of the tyrosine kinase Src in both the presence and absence of an Hsp90 inhibitor. We identified 84 previously unknown functionally dependent client variants. Unexpectedly, many destabilized or extended variants were not functionally dependent on Hsp90. Instead, functionally dependent client variants were clustered in the αF pocket and β1–β2 strand regions of Src, which have yet to be described in driving Hsp90 dependence. Hsp90 dependence was also strongly correlated with kinase activity. We found that a combination of activation, global extension, and general conformational flexibility, primarily induced by variants at the αF pocket and β1–β2 strands, was necessary to render Src functionally dependent on Hsp90. Moreover, the degree of activation and flexibility required to transform Src into a functionally dependent client varied with variant location, suggesting that a combination of regulatory domain disengagement and catalytic domain flexibility are required for chaperone dependence. Thus, by studying the chaperone dependence of a massive number of variants, we highlight factors driving Hsp90 client specificity and propose a model of chaperone‐kinase interactions. [ABSTRACT FROM AUTHOR]

Abstract Background Heat shock protein (HSP) 90 functions as a molecular chaperone and is constitutively expressed and induced in response to stress in many cell types. We have previously demonstrated that transforming growth factor-β (TGF-β), the most abundant cytokine in bone cells, induces the expression of HSP27 through Smad2, p44/p42 mitogen-activated protein kinase (MAPK), p38 MAPK, and stress-activated protein kinase/c-Jun N-terminal kinase (SAPK/JNK) in mouse osteoblastic MC3T3-E1 cells. This study investigated the effects of HSP90 on the TGF-β-induced HSP27 expression and the underlying mechanism in mouse osteoblastic MC3T3-E1 cells. Methods Clonal osteoblastic MC3T3-E1 cells were treated with the HSP90 inhibitors and then stimulated with TGF-β. HSP27 expression and the phosphorylation of Smad2, p44/p42 MAPK, p38 MAPK, and SAPK/JNK were evaluated by western blot analysis. Result HSP90 inhibitors 17-dimethylaminoethylamino-17-demethoxy-geldanamycin (17-DMAG) and onalespib significantly enhanced the TGF-β-induced HSP27 expression. TGF-β inhibitor SB431542 reduced the enhancement by 17-DMAG or onalespib of the TGF-β-induced HSP27 expression levels. HSP90 inhibitors, geldanamycin, onalespib, and 17-DMAG did not affect the TGF-β-stimulated phosphorylation of Smad2. Geldanamycin did not affect the TGF-β-stimulated phosphorylation of p44/p42 MAPK or p38 MAPK but significantly enhanced the TGF-β-stimulated phosphorylation of SAPK/JNK. Onalespib also increased the TGF-β-stimulated phosphorylation of SAPK/JNK. Furthermore, SP600125, a specific inhibitor for SAPK/JNK, significantly suppressed onalespib or geldanamycin’s enhancing effect of the TGF-β-induced HSP27 expression levels. Conclusion Our results strongly suggest that HSP90 inhibitors upregulated the TGF-β-induced HSP27 expression and that these effects of HSP90 inhibitors were mediated through SAPK/JNK pathway in osteoblasts.

Abstract Background With the widespread clinical application of tyrosine kinase inhibitors (TKIs), an increasing number of chronic myeloid leukaemia (CML) patients have developed resistance or intolerance to TKIs. BCR/ABL is the oncoprotein of CML. HSP90 is an essential chaperone of BCR/ABL and plays an important role in protein folding and the function of BCR/ABL. Therefore, inhibiting the chaperone function of HSP90 may be an effective strategy for CML treatment and to overcome TKI resistance. Methods The effect of KW-2478 on CML cell viability, apoptosis and cell cycle progression was detected by CCK-8 assay or flow cytometry. The levels of BCR/ABL, HSP90 and other signalling proteins were detected by western blots. The mitochondrial membrane potential was detected by flow cytometry combined with JC-1 staining. The interaction between BCR/ABL and HSP90α was detected by coimmunoprecipitation. The effect of KW-2478 on BCR/ABL carcinogenesis in vivo was investigated in CML-like mouse models. Results KW-2478 inhibited growth and induced apoptosis of CML cells. KW-2478 inhibited the chaperone function of HSP90α and then weakened the BCR/ABL and MAPK signalling pathways. This treatment also caused an increase in p27 and p21 expression and a decrease in cyclin B1 expression, which led to G2/M phase arrest. The mitochondrial pathway was primarily responsible for KW-2478-induced apoptosis. KW-2478 had a synergistic effect with imatinib in growth inhibition. Notably, KW-2478 had a stronger effect on growth inhibition, apoptosis induction and cell cycle arrest of K562/G01 cells than K562 cells. KW-2478 could effectively prolong the mouse lifespan and alleviate disease symptoms in CML-like mouse models. Conclusions This finding demonstrated that KW-2478 had anticancer properties in imatinib-sensitive and imatinib-resistant CML cells and illustrated the possible mechanisms. This study provides an alternative choice for CML treatment, especially for TKI-resistant patients with BCR/ABL amplification and TKI-intolerant patients.

Photodynamic therapy is a promising and effective non-invasive therapeutic approach for the treatment of bladder cancers. Therapies targeting HSP90 have the advantage of tumor cell selectivity and have shown great preclinical efficacy. In this study, we evaluated a novel multifunctional nanoporphyrin platform loaded with an HSP90 inhibitor 17AAG (NP-AAG) for use as a multi-modality therapy against bladder cancer. NP-AAG was efficiently accumulated and retained at bladder cancer patient-derived xenograft (PDX) over 7 days. PDX tumors could be synergistically eradicated with a single intravenous injection of NP-AAG followed by multiple light treatments within 7 days. NP-AAG mediated treatment could not only specifically deliver 17AAG and produce heat and reactive oxygen species, but also more effectively inhibit essential bladder cancer essential signaling molecules like Akt, Src, and Erk, as well as HIF-1α induced by photo-therapy. This multifunctional nanoplatform has high clinical relevance and could dramatically improve management for bladder cancers with minimal toxicity.

Heat shock proteins (Hsps) have garnered special attention in cancer therapy as molecular chaperones with regulatory/mediatory effects on folding, maintenance/stability, maturation, and conformation of proteins as well as their effects on prevention of protein aggregation. Hsp90 ensures the stability of various client proteins needed for the growth of cells or the survival of tumor cells; therefore, they are overexpressed in tumor cells and play key roles in carcinogenesis. Accordingly, Hsp90 inhibitors are recognized as attractive therapeutic agents for investigations pertaining to tumor suppression. Natural Hsp90 inhibitors comprising geldanamycin (GM), reclaimed analogs of GM including 17-AAG and DMAG, and radicicol, a natural macrocyclic antifungal, are among the first potent Hsp90 inhibitors. Herein, recently synthesized heterocyclic compounds recognized as potent Hsp90 inhibitors are reviewed along with the anticancer effects of heterocyclic compounds, comprising purine, pyrazole, triazine, quinolines, coumarin, and isoxazoles molecules. [ABSTRACT FROM AUTHOR]

Summary: This study compared the bioavailability of two pimitespib formulations (Formulations A and B), evaluated the food effect on Formulation A, and evaluated the safety and efficacy of multiple pimitespib doses in patients with solid tumors. This clinical, pharmacological multicenter study had two cohorts and periods. A single dose of Formulation A or B was administered in a crossover design to compare the pharmacokinetics in Cohort 1. In Cohort 2, the effects of fed vs fasting conditions were evaluated among those receiving Formulation A. Subsequently, multiple Formulation A doses were administered to all patients for safety and efficacy assessments. In Cohorts 1 and 2, 12 and 16 patients, respectively, were analyzed for pharmacokinetics. Thirty patients were analyzed for safety and efficacy. Maximum concentration (Cmax), area under the curve (AUC)last, and AUCinf geometric mean ratios for Formulations A and B (90% confidence interval [CI]) were 0.8078 (0.6569–0.9933), 0.7973 (0.6672–0.9529), and 0.8094 (0.6697–0.9782), respectively; 90% CIs were not within the bioequivalence range (0.80–1.25). In Cohort 2, mean Cmax, AUClast, and AUCinf were higher in fed vs fasting conditions. No safety concerns emerged with single or multiple administration. Overall response rate, disease control rate, and median progression-free survival were 0%, 33%, and 1.5 months, respectively. Four patients had stable disease ≥ 5 months. Bioequivalence of the two formulations was unconfirmed. Systemic exposure of Formulation A was approximately 20% less than Formulation B. A high-fat/calorie meal increased the relative pharmacokinetics and bioavailability of a single 160-mg dose. Trial Registration: JapicCTI-184191 (Japan Pharmaceutical Information Center) registered on November 5, 2018. [ABSTRACT FROM AUTHOR]

Topo II and Hsp90 are promising targets. In this study, we first verified the structural similarities between Topo IIα ATPase and Hsp90α N−ATPase. Subsequently, 720 compounds from the Food and Drug Administration (FDA) drug library and kinase library were screened using the malachite green phosphate combination with the Topo II-mediated DNA relaxation and MTT assays. Subsequently, the antimalarial drug quinacrine was found to be a potential dual−target inhibitor of Topo II and Hsp90. Mechanistic studies showed that quinacrine could specifically bind to the Topo IIα ATPase domain and inhibit the activity of Topo IIα ATPase without impacting DNA cleavage. Furthermore, our study revealed that quinacrine could bind Hsp90 N−ATPase and inhibit Hsp90 activity. Significantly, quinacrine has broad antiproliferation activity and remains sensitive to the multidrug−resistant cell line MCF−7/ADR and the atypical drug−resistant tumor cell line HL−60/MX2. Our study identified quinacrine as a potential dual−target inhibitor of Topo II and Hsp90, depending on the ATP−binding domain, positioning it as a hit compound for further structural modification. [ABSTRACT FROM AUTHOR]

Prognosis of advanced gastrointestinal stromal tumors (GIST) refractory to tyrosine kinase inhibitors (TKIs) is poor. This randomized, placebo-controlled, phase III trial evaluated the efficacy and safety of pimitespib, a novel heat shock protein 90 inhibitor, in advanced GIST refractory to standard TKIs. Patients with histologically confirmed GIST refractory to imatinib, sunitinib, and regorafenib were randomized 2 : 1 to oral pimitespib 160 mg/day or placebo for 5 consecutive days per week in 21-day cycles. Following disease progression by blinded central radiological review (BCRR), cross-over to open-label pimitespib was permitted. The primary endpoint was progression-free survival (PFS) by BCRR in the full analysis set. Secondary endpoints included overall survival (OS) adjusted using the rank-preserving structural failure time (RPSFT) method to reduce the expected confounding impact of cross-over. From 31 October 2018 to 30 April 2020, 86 patients were randomized to pimitespib (n = 58) or placebo (n = 28). Median PFS was 2.8 months [95% confidence interval (CI) 1.6-2.9 months] with pimitespib versus 1.4 months (0.9-1.8 months) with placebo [hazard ratio (HR) 0.51 (95% CI 0.30-0.87); one-sided P = 0.006]. Pimitespib showed an improvement in cross-over-adjusted OS compared with placebo [HR 0.42 (0.21-0.85), one-sided P = 0.007]. Seventeen (60.7%) patients receiving placebo crossed-over to pimitespib; median PFS after cross-over was 2.7 months (95% CI 0.7-4.1 months). The most common (≥30%) treatment-related adverse events (AEs) with pimitespib were diarrhea (74.1%) and decreased appetite (31.0%); the most common (≥10%) grade ≥3 treatment-related AE was diarrhea (13.8%). Treatment-related AEs leading to pimitespib discontinuation occurred in three (5.2%) patients. Pimitespib significantly improved PFS and cross-over-adjusted OS compared with placebo and had an acceptable safety profile in patients with advanced GIST refractory to standard TKIs. • Pimitespib improved PFS compared with placebo in patients with previously treated advanced GIST. • OS was improved with pimitespib compared with placebo using the RPSFT model. • Exploratory pharmacogenomic analysis showed a benefit of pimitespib irrespective of KIT mutation status. • The safety profile of pimitespib was acceptable, with no deterioration in quality of life compared to placebo. [ABSTRACT FROM AUTHOR]

Background/aim: Breast cancer is the most predominant type of cancer affecting women worldwide and the current therapeutic treatment for breast cancer patients is not adequately effective. This study aimed to investigate the mechanism of 17-AAG, a heat shock protein (HSP90) inhibitor, as a treatment for inducing breast cancer cell apoptosis., Materials and Methods: The pharmacology network was employed to examine the correlation of 17-AAG with the gene expression profiles of breast cancer, obtained by Gene Expression Profiling Interactive Analysis (GEPIA). MTT and flow cytometry were utilized to investigate cell proliferation and cell apoptosis, respectively. Dichloro-dihydro-fluorescein diacetate (DCFH-DA) assay and western blot analysis were employed to examine the correlation between cellular oxidant levels and protein expression. Immunofluorescence staining was utilized to confirm the protein localization and assess DNA damage., Results: The pharmacological network analysis revealed that HSP90 serves as the common target connecting 17-AAG and breast cancer genes. Treatment with 17-AAG significantly increased cell apoptosis. Moreover, the treatment resulted in up-regulation of cellular oxidant levels and PERK/eIF2α expression. In line with these, protein localization after treatment revealed an increase in DNA damage, correlating with higher ER stress levels. Furthermore, GEPIA demonstrated that PERK and eIF2α expression were significantly higher in breast invasive carcinoma compared to other tumor types., Conclusion: HSP90 emerges as a potential target for inducing apoptosis in breast cancer cells by disrupting protein homeostasis in the endoplasmic reticulum, possibly through PERK/eIF2α up-regulation. 17-AAG, an HSP90 inhibitor, may therefore potentially hold an alternative therapeutic strategy for breast cancer treatment., (Copyright © 2024, International Institute of Anticancer Research (Dr. George J. Delinasios), All rights reserved.)

In a previous study, we suggested that the Hsp90 inhibitor 17-AAG prevents cardiac dysfunction in the failing heart following myocardial infarction in rats. Although it is assumed that the RIP1/RIP3/MLKL necroptotic pathway, which comprises client proteins for Hsp90, is involved; however, the relationship between the cardioprotective effects of 17-AAG and the activity of the cardiac RIP1/RIP3/MLKL necrosome-associated proteins in the failing heart following myocardial infarction remained unclear. Therefore, the levels of phosphorylated MLKL after myocardial infarction with or without Hsp90 inhibitor treatment were measured. Myocardial infarction was induced by ligation of the coronary artery (CAL) in Wistar rats. 17-AAG was injected from the 2nd to the 8th week after myocardial infarction. The administration of 17-AAG attenuated the cardiac dysfunction, hypertrophy, and fibrosis at the 8th week after CAL, simultaneously lessening the increases in the expression and phosphorylation levels of RIP1, RIP3, and MLKL in the area of the left ventricular muscle without infarct. These results indicate that the activation of the RIP1/RIP3/MLKL pathway is a common event in the development of chronic heart failure. Furthermore, our findings suggest that the effects of 17-AAG treatment on the improvement of cardiac function in rats after myocardial infarction is related to the attenuation of this RIP1/RIP3/MLKL pathway.

Abstract Background Photothermal therapy (PTT) has been extensively investigated as a tumor-localizing therapeutic modality for neoplastic disorders. However, the hyperthermia effect of PTT is greatly restricted by the thermoresistance of tumor cells. Particularly, the compensatory expression of heat shock protein 90 (HSP90) has been found to significantly accelerate the thermal tolerance of tumor cells. Thus, a combination of HSP90 inhibitor and photothermal photosensitizer is expected to significantly enhance antitumor efficacy of PTT through hyperthermia sensitization. However, it remains challenging to precisely co-deliver two or more drugs into tumors. Methods A carrier-free co-delivery nanoassembly of gambogic acid (GA, a HSP90 inhibitor) and DiR is ingeniously fabricated based on a facile and precise molecular co-assembly technique. The assembly mechanisms, photothermal conversion efficiency, laser-triggered drug release, cellular uptake, synergistic cytotoxicity of the nanoassembly are investigated in vitro. Furthermore, the pharmacokinetics, biodistribution and self-enhanced PTT efficacy were explored in vivo. Results The nanoassembly presents multiple advantages throughout the whole drug delivery process, including carrier-free fabrication with good reproducibility, high drug co-loading efficiency with convenient dose adjustment, synchronous co-delivery of DiR and GA with long systemic circulation, as well as self-tracing tumor accumulation with efficient photothermal conversion. As expected, HSP90 inhibition-augmented PTT is observed in a 4T1 tumor BALB/c mice xenograft model. Conclusion Our study provides a novel and facile dual-drug co-assembly strategy for self-sensitized cancer therapy. Graphic abstract

Ulcerative colitis (UC) is a prevalent type of inflammatory bowel diseases that may predispose patients to acquire colitis-related cancer if treatment was not effective. Despite the presence of an array of established treatment options, current modalities are not successful for a substanial number of patients. The activation of the NLRP3 inflammasome is critical in the development of inflammatory processes in the colon. Additionally, the regulation of NLRP3 via HSP90 inhibition is a potential target to treat UC. Moreover, during inflammation, autophagy allows the turnover of malfunctioning proteins and therefore stands as a viable strategy for inactivating NLRP3 inflammasomes and halting hyperinflammation. Herein, we evaluated the effect of autophagy induction using metformin in the context of HSP90 inhibition by TAS-116 in the dextran sodium sulfate (DSS)-induced UC in rats. We revealed that TAS-116-induced interruption of the protein complex containing HSP90 and NLRP3 might hamper and delay the start of the inflammatory cascade ensued by the NLRP3 inflammasome oligomerization. In such circumstances, the unprotected NLRP3 is subjected to autophagic degradation in an environment of metformin-promoted autophagic signaling. As a result, such dynamic synergy was efficient in combating colon damage and immune-cell infiltration. This was confirmed by the macroscopic and microscopic investigations. Further, biochemical analysis revealed subdued inflammation cascade and oxidative injury. Therefore, simultaneous administration of TAS-116 and metformin is a new management paradigm aimed at inducing malfunction in the NLRP3 followed by augmenting its autophagic degradation, respectively. However, further studies should be conducted to assess the reliability and consistency of this novel approach.

Despite several treatment options for blood cancer, mortality remains high due to relapse and the disease’s aggressive nature. Elevated levels of HSP90, a molecular chaperone essential for protein folding, are associated with poor prognosis in leukemia and lymphoma. HSP90 as a target for chemotherapy has been met with limited success due to toxicity and induction of heat shock. This study tested the activity of an HSP90 inhibitor, SP11, against leukemic cells, mouse lymphoma allograft, and xenograft models. SP11 induced cytotoxicity in vitro in leukemic cell lines and induced cell death via apoptosis, with minimal effect on normal cells. SP11 induced cell death by altering the status of HSP90 client proteins both in vitro and in vivo. SP11 reduced the tumor burden in allograft and xenograft mouse models without apparent toxicity. The half-life of SP11 in the plasma was approximately 2 h. SP11 binding was observed at both the N-terminal and C-terminal domains of HSP90. C-terminal binding was more potent than N-terminal binding of HSP90 in silico and in vitro using isothermal calorimetry. SP11 bioavailability and minimal toxicity in vivo make it a potential candidate to be developed as a novel anticancer agent.

Triple negative breast cancer (TNBC) is highly malignant and prone to recurrence and metastasis. Patients with TNBC usually have poor prognosis. Hence, it is urgent to develop new comprehensive treatments for TNBC. The combination of heat shock protein (HSP) inhibitor and the photothermal agent can reduce the temperature required to kill tumor cells, thus achieving mild-temperature photothermal therapy (PTT). Compared with traditional PTT, mild-temperature PTT not only decreases tumor thermoresistance introduced by the overexpression of HSP, but also reduces the damage to normal tissues. Meanwhile, Azo initiator 2,2-azobis[2-(2-imidazolin-2-yl) propane]-dihydroch-loride (AIPH) can be thermally decomposed to generate oxygen-independent free radicals. Herein, a new therapeutic multifunctional nanoplatform (M-17AAG-AIPH) by loading heat shock protein 90 (HSP90) inhibitor (17AAG) and AIPH incorporated into mesoporous polydopamine (MPDA) was successfully constructed for mild-temperature PTT combined with oxygen-independent cytotoxic free radicals against TNBC. Under 808 nm laser irradiation, the mild-temperature PTT arising from the combined effects of 17AAG and MPDA induced a rapid release and decomposition of AIPH, promoting the apoptosis of cancer cells in hypoxic microenvironments. Both in vitro and in vivo results showed that the designed nanoplatform can significantly inhibit tumor growth and provided an efficient new therapeutic strategy for TNBC. There is still an urgent need for new strategies for the treatment of triple negative breast cancer (TNBC). In this work, we successfully constructed a new therapeutic multifunctional nanoplatform (M-17AAG-AIPH) by co-carrying heat shock protein 90 (HSP90) inhibitor (17AAG) and AIPH on mesoporous polydopamine (MPDA). MPDA owned good biocompatibility and outstanding photothermal-conversion ability. The loading of 17AAG can reduce the heat resistance of tumor cells via specifically inhibiting the activity of HSP90, so as to achieve mild-temperature PTT. Meanwhile, 17AAG and MPDA mediated mild-temperature PTT promoted the decomposition of AIPH into oxygen-independent cytotoxic free radicals. Both in vitro and in vivo results showed that M-17AAG-AIPH can significantly inhibit tumor growth and provided an efficient new therapeutic strategy for TNBC. [Display omitted] [ABSTRACT FROM AUTHOR]

Invasive candidiasis is the primary reason for the increased cases of mortality in a medical environment. The resistance spectra of Candida species to antifungal drugs have gradually expanded. Particularly, the resistance spectra of Candida auris are the most prominent. Hsp90 plays a protective role in the stress response of fungi and facilitates their virulence. In contrast, Hsp90 inhibitors can improve the resistance of fungi to antifungal drugs by regulating the heat resistance of Hsp90, which destroys the integrity of the fungal cell walls. Hsp90 inhibitors thus offer a great potential to reduce or address fungal drug resistance. The drugs tested for the resistance include itraconazole, voriconazole, posaconazole, fluconazole, and 17-AAG. A total of 20 clinical strains of Candida were investigated. The broth microdilution checkerboard technique, as adapted from the CLSI M27-A4 method, was applied in this study. We found that 17-AAG alone exerted limited antifungal activity against all tested strains. The MIC range of 17-AAG was 8 to >32μg/ ml. A synergy was observed among 17-AAG and itraconazole, voriconazole, and posaconazole against 10 (50%), 7 (35%), and 13 (65%) of all isolates, respectively. Moreover, the synergy between 17-AAG and fluconazole was observed against 5 (50%) strains of azole-resistant Candida. However, no antagonism was recorded overall. Our result adequately verifies the influence of 17-AAG on the formation of Candida spp. biofilm. Moreover, we determined that with the use of rhodamine 6G to detect drug efflux and that of dihydrorhodamine-123 to detect intracellular reactive oxygen species (ROS), treatment with 17-AAG combined with azole drugs could inhibit the efflux pump of fungi and promote the accumulation of ROS in the fungal cells, thereby inducing fungal cell apoptosis. Thus, the mechanism of 17-AAG combined with azoles can kill fungi. Our results thus provide a new idea to further explore drugs against drug-resistant Candida spp. [ABSTRACT FROM AUTHOR]

Purpose Heat shock protein-90 (HSP90) remains an important cancer target because of its involvement in multiple oncogenic protein pathways and biologic processes. Although many HSP90 inhibitors have been tested in the treatment of KRAS-mutant non–small cell lung cancer (NSCLC), most, including AUY922, have failed due to toxic effects and resistance generation, even though a modest efficacy has been observed for these drugs in clinical trials. In our present study, we investigated the novel mechanism of resistance to AUY922 to explore possible avenues of overcoming and want to provide some insights that may assist with the future development of successful next-generation HSP90 inhibitors. Materials and Methods We established two AUY922-resistant KRAS-mutated NSCLC cells and conducted RNA sequencing to identify novel resistance biomarker. Results We identified novel two resistance biomarkers. We observed that both integrin Av (ITGAv) and β3 (ITGB3) induce AUY922- resistance via focal adhesion kinase (FAK) activation, as well as an epithelial-mesenchymal transition, in both in vitro and in vivo xenograft model. mRNAs of both ITGAv and ITGB3 were also found to be elevated in a patient who had shown acquired resistance in a clinical trial of AUY922. ITGAv was induced by miR-142 downregulation, and ITGB3 was increased by miR-150 downregulation during the development of AUY922-resistance. Therefore, miR-150 and miR-142 overexpression effectively inhibited ITGAvB3-dependent FAK activation, restoring sensitivity to AUY922. Conclusion The synergistic co-targeting of FAK and HSP90 attenuated the growth of ITGAvB3-induced AUY922-resistant KRASmutated NSCLC cells in vitro and in vivo, suggesting that this combination may overcome acquired AUY922-resistance in KRASmutant NSCLC. [ABSTRACT FROM AUTHOR]

We have demonstrated that epidermal growth factor (EGF)-induced migration of osteoblast-like MC3T3-E1 cells is mediated through p44/p42 mitogen-activated protein (MAP) kinase, p38 MAP kinase, stress-activated protein kinase/ c-Jun N-terminal kinase (SAPK/JNK), and Akt.The molecular chaperone heat shock protein 90 (HSP90) is abundantly expressed in osteoblasts. However, the role of HSP90 in osteoblast migration remains obscure. In this study, we investigated the effect of HSP90 inhibitors on the EGF-induced migration of MC3T3-E1 cells and the mechanism. Clonal osteoblast-like MC3T3-E1 cells were treated with the HSP90 inhibitors geldanamycin or onalespib and then stimulated with EGF. Cell migration was evaluated using the transwell cell migration assay and wound-healing assay. The viability of MC3T3-E1 cells was analyzed using the Cell Counting Kit-8. The phosphorylation of p44/p42 MAP kinase, p38 MAP kinase, SAPK/JNK, Akt, and protein kinase-like endoplasmic reticulum kinase (PERK) was evaluated by western blot analysis. EGF-induced migration was significantly suppressed by geldanamycin and onalespib, evaluated by both transwell cell migration assay and wound-healing assay. Geldanamycin and onalespib did not significantly alter cell viability. Geldanamycin and onalespib markedly reduced the EGF-induced phosphorylation of p44/p42 MAP kinase, but not p38 MAP kinase or Akt. By contrast, geldanamycin and onalespib increased the EGF-induced phosphorylation of SAPK/JNK. PERK phosphorylation was not significantly affected by geldanamycin or onalespib. Our results strongly suggest that HSP90 inhibitors reduce the EGF-induced osteoblast migration through the p44/p42 MAP kinase. [ABSTRACT FROM AUTHOR]

The rational design of the nanocarriers with active tumor targeting and specific chemotherapy for heat shock protein 90 (Hsp90) inhibition is attractive for combined chemo-photothermal therapy (PTT). Herein, a smart gold nanorod (GNR)-cored micelle (T-GNRAAG) was developed to encapsulate 17-allylamino-17-demethoxygeldanamycin (17-AAG, Hsp90 inhibitor) through a facile preparation approach. The characteristics of T-GNRAAG were evaluated both in vitro and in vivo. The designed nanoplatform possessed sufficient 17-AAG loading content and lactobionic acid-mediated active targeting for hepatoma cells. More importantly, the 808 nm laser irradiation not only initiated PTT for cell killing but also remotely triggered 17-AAG liberation within cancer cells via inducing the phase transition of poly(ɛ-caprolactone). All these features forcefully supported the effectiveness of T-GNRAAG in tumor growth inhibition. This work represents a proof-of-concept combinatorial chemo-PTT treatment.

Chenwei Pan,1,* Tiaotiao Zhang,2,3,* Shaoxun Li,1,3,* Zhihua Xu,2,3 Binhui Pan,2,3 Sheng Xu,2,3 Shuanghong Jin,1,3 Guangrong Lu,2 Shouxing Yang,2 Zhanxiong Xue,2 Ping Chen,4 Xian Shen,5 Fangyan Wang,6 Changlong Xu2,7 1Department of Infectious Disease, Second Affiliated Hospital and Yuying Children’s Hospital of Wenzhou Medical University, Wenzhou, Zhejiang, 325000, People’s Republic of China; 2Department of Gastroenterology, Second Affiliated Hospital and Yuying Children’s Hospital of Wenzhou Medical University, Wenzhou, Zhejiang, 325000, People’s Republic of China; 3Second School of Medicine, Wenzhou Medical University, Wenzhou, Zhejiang, 325000, People’s Republic of China; 4Department of Infectious Disease, Shulan Hospital, Hangzhou, Zhejiang, 310012, People’s Republic of China; 5Department of Gastrointestinal Surgery, Second Affiliated Hospital and Yuying Children’s Hospital of Wenzhou Medical University, Wenzhou, Zhejiang, 325000, People’s Republic of China; 6Department of Pathophysiology, School of Basic Medicine Science, Wenzhou Medical University, Wenzhou, Zhejiang, 325000, People’s Republic of China; 7Center for Diagnostics and Therapeutics, Institute for Biomedical Sciences, Georgia State University, Atlanta, GA, 30302, USA*These authors contributed equally to this workCorrespondence: Fangyan Wang; Changlong Xu Email wzyxywfy@126.com; xchlong@163.comBackground: As a therapeutic target for cancer treatment, HSP90 has been explored extensively. However, the significant side effects of the HSP90 inhibitor 17AAG have limited its clinical use.Methods: In this study, we used hyaluronic acid (HA)–decorated DOTAP–PLGA hybrid nanoparticles (HA-DOTAP-PLGA NPs) as 17AAG-delivery carriers for targeted colon cancer therapy.Results: Different methods were used to characterize the successful fabrication of these hybrid PLGA NPs. Our results demonstrated that internalization of HA-NPs in colon cancer cells was governed by CD44receptor–mediated endocytosis. Annexin V–propidium iodide staining experiments revealed that cell apoptosis induced by HA-NPs-17AAG in colon cancer cells was more efficient than free 17AAG. In two animal models used to screen anticancer efficacy (Luc-HT29 subcutaneous xenograft and AOM/DSS-induced orthotopic tumor model), HA-NPs-17AAG significantly inhibited xenograft and orthotopic tumor growth, demonstrating HA-NPs-17AAG had much better therapeutic efficiency than free 17AAG. It is worth noting that great biocompatibility of HA-DOTAP-PLGA NPs was observed both in vitro and in vivo.Conclusion: Our research offers a preclinical proof of concept for colon cancer therapy with DOTAP-PLGA NPs as a creative drug-delivery system.Keywords: cationic hybrid nanoparticles, hyaluronic acid, HA, HSP90 inhibitor, colon cancer, targeted delivery system

Background: Heat shock protein (HSP) 90 functions as a molecular chaperone and is constitutively expressed and induced in response to stress in many cell types. We have previously demonstrated that transforming growth factor-β (TGF-β), the most abundant cytokine in bone cells, induces the expression of HSP27 through Smad2, p44/p42 mitogen-activated protein kinase (MAPK), p38 MAPK, and stress-activated protein kinase/c-Jun N-terminal kinase (SAPK/JNK) in mouse osteoblastic MC3T3-E1 cells. This study investigated the effects of HSP90 on the TGF-β-induced HSP27 expression and the underlying mechanism in mouse osteoblastic MC3T3-E1 cells.Methods: Clonal osteoblastic MC3T3-E1 cells were treated with the HSP90 inhibitors and then stimulated with TGF-β. HSP27 expression and the phosphorylation of Smad2, p44/p42 MAPK, p38 MAPK, and SAPK/JNK were evaluated by western blot analysis.Result: HSP90 inhibitors 17-dimethylaminoethylamino-17-demethoxy-geldanamycin (17-DMAG) and onalespib significantly enhanced the TGF-β-induced HSP27 expression. TGF-β inhibitor SB431542 reduced the enhancement by 17-DMAG or onalespib of the TGF-β-induced HSP27 expression levels. HSP90 inhibitors, geldanamycin, onalespib, and 17-DMAG did not affect the TGF-β-stimulated phosphorylation of Smad2. Geldanamycin did not affect the TGF-β-stimulated phosphorylation of p44/p42 MAPK or p38 MAPK but significantly enhanced the TGF-β-stimulated phosphorylation of SAPK/JNK. Onalespib also increased the TGF-β-stimulated phosphorylation of SAPK/JNK. Furthermore, SP600125, a specific inhibitor for SAPK/JNK, significantly suppressed onalespib or geldanamycin's enhancing effect of the TGF-β-induced HSP27 expression levels.Conclusion: Our results strongly suggest that HSP90 inhibitors upregulated the TGF-β-induced HSP27 expression and that these effects of HSP90 inhibitors were mediated through SAPK/JNK pathway in osteoblasts. [ABSTRACT FROM AUTHOR]

Background: With the widespread clinical application of tyrosine kinase inhibitors (TKIs), an increasing number of chronic myeloid leukaemia (CML) patients have developed resistance or intolerance to TKIs. BCR/ABL is the oncoprotein of CML. HSP90 is an essential chaperone of BCR/ABL and plays an important role in protein folding and the function of BCR/ABL. Therefore, inhibiting the chaperone function of HSP90 may be an effective strategy for CML treatment and to overcome TKI resistance. Methods: The effect of KW-2478 on CML cell viability, apoptosis and cell cycle progression was detected by CCK-8 assay or flow cytometry. The levels of BCR/ABL, HSP90 and other signalling proteins were detected by western blots. The mitochondrial membrane potential was detected by flow cytometry combined with JC-1 staining. The interaction between BCR/ABL and HSP90α was detected by coimmunoprecipitation. The effect of KW-2478 on BCR/ABL carcinogenesis in vivo was investigated in CML-like mouse models. Results: KW-2478 inhibited growth and induced apoptosis of CML cells. KW-2478 inhibited the chaperone function of HSP90α and then weakened the BCR/ABL and MAPK signalling pathways. This treatment also caused an increase in p27 and p21 expression and a decrease in cyclin B1 expression, which led to G2/M phase arrest. The mitochondrial pathway was primarily responsible for KW-2478-induced apoptosis. KW-2478 had a synergistic effect with imatinib in growth inhibition. Notably, KW-2478 had a stronger effect on growth inhibition, apoptosis induction and cell cycle arrest of K562/G01 cells than K562 cells. KW-2478 could effectively prolong the mouse lifespan and alleviate disease symptoms in CML-like mouse models. Conclusions: This finding demonstrated that KW-2478 had anticancer properties in imatinib-sensitive and imatinib-resistant CML cells and illustrated the possible mechanisms. This study provides an alternative choice for CML treatment, especially for TKI-resistant patients with BCR/ABL amplification and TKI-intolerant patients. [ABSTRACT FROM AUTHOR]

KIT is a type-III receptor tyrosine kinase that contributes to cell signaling in various cells. Since KIT is activated by overexpression or mutation and plays an important role in the development of some cancers, such as gastrointestinal stromal tumors and mast cell disease, molecular therapies targeting KIT mutations are being developed. In acute myeloid leukemia (AML), genome profiling via next-generation sequencing has shown that several genes that are mutated in patients with AML impact patients' prognosis. Moreover, it was suggested that precision-medicine-based treatment using genomic data will improve treatment outcomes for AML patients. This paper presents (1) previous studies regarding the role of KIT mutations in AML, (2) the data in AML with KIT mutations from the HM-SCREEN-Japan-01 study, a genome profiling study for patients newly diagnosed with AML who are unsuitable for the standard first-line treatment (unfit) or have relapsed/refractory AML, and (3) new therapies targeting KIT mutations, such as tyrosine kinase inhibitors and heat shock protein 90 inhibitors. In this era when genome profiling via next-generation sequencing is becoming more common, KIT mutations are attractive novel molecular targets in AML. [ABSTRACT FROM AUTHOR]

Aims: MORC family CW‐type zinc finger 2 (MORC2), a GHKL‐type ATPase, is aberrantly upregulated in multiple types of human tumors with profound effects on cancer aggressiveness, therapeutic resistance, and clinical outcome, thus making it an attractive drug target for anticancer therapy. However, the antagonists of MORC2 have not yet been documented. Methods and Results: We report that MORC2 is a relatively stable protein, and the N‐terminal homodimerization but not ATP binding and hydrolysis is crucial for its stability through immunoblotting analysis and Quantitative real‐time PCR. The N‐terminal but not C‐terminal inhibitors of heat shock protein 90 (HSP90) destabilize MORC2 in multiple cancer cell lines, and strikingly, this process is independent on HSP90. Mechanistical investigations revealed that HSP90 N‐terminal inhibitors disrupt MORC2 homodimer formation without affecting its ATPase activities, and promote its lysosomal degradation through the chaperone‐mediated autophagy pathway. Consequently, HSP90 inhibitor 17‐AAG effectively blocks the growth and metastatic potential of MORC2‐expressing breast cancer cells both in vitro and in vivo, and these noted effects are not due to HSP90 inhibition. Conclusion: We uncover a previously unknown role for HSP90 N‐terminal inhibitors in promoting MORC2 degradation in a HSP90‐indepentent manner and support the potential application of these inhibitors for treating MORC2‐overexpressing tumors, even those with low or absent HSP90 expression. These results also provide new clue for further design of novel small‐molecule inhibitors of MORC2 for anticancer therapeutic application. [ABSTRACT FROM AUTHOR]

The use of targeted inhibitors has shown promise as an effective approach in cancer therapy. However, targeted therapies based only on one drug, such as 17-allylamino-17-demethoxygeldanamycin (17-AAG), have limited success, partly because cancer cells engage alternate pathways for survival and proliferation. In the present study, we evaluated whether dehydroxymethylepoxyquinomicin (DHMEQ), a nuclear factor κB (NF-κB) inhibitor, can enhance the antitumor activities of 17-AAG, a 90 kDa heat shock protein (Hsp90) inhibitor, in the anaplastic thyroid cancer cell line KTC2. We examined the effect of combined drug treatment vs single drug treatment on cell survival. Isobologram analysis was performed to distinguish the additive vs synergistic effects of the drug combination. Western blotting was performed to investigate apoptosis markers: caspase 3, poly(ADP-ribose) polymerase-one (PARP-1), B-cell lymphoma-extra large (Bcl-XL), X-linked inhibitor of apoptosis (XIAP) and cellular inhibitor of apoptosis 2 (cIAP-2). Compared to monotherapy, the combined treatment enhanced growth-inhibitory effects in a synergistic manner and strongly potentiated apoptosis. These results demonstrate the first in vitro evidence that a combination of Hsp90 and NF-κB inhibitors is a more effective modality for inhibiting cell proliferation and survival in anaplastic thyroid carcinoma cells than either agent alone, warranting further investigations.

Abstract Aims MORC family CW‐type zinc finger 2 (MORC2), a GHKL‐type ATPase, is aberrantly upregulated in multiple types of human tumors with profound effects on cancer aggressiveness, therapeutic resistance, and clinical outcome, thus making it an attractive drug target for anticancer therapy. However, the antagonists of MORC2 have not yet been documented. Methods and Results We report that MORC2 is a relatively stable protein, and the N‐terminal homodimerization but not ATP binding and hydrolysis is crucial for its stability through immunoblotting analysis and Quantitative real‐time PCR. The N‐terminal but not C‐terminal inhibitors of heat shock protein 90 (HSP90) destabilize MORC2 in multiple cancer cell lines, and strikingly, this process is independent on HSP90. Mechanistical investigations revealed that HSP90 N‐terminal inhibitors disrupt MORC2 homodimer formation without affecting its ATPase activities, and promote its lysosomal degradation through the chaperone‐mediated autophagy pathway. Consequently, HSP90 inhibitor 17‐AAG effectively blocks the growth and metastatic potential of MORC2‐expressing breast cancer cells both in vitro and in vivo, and these noted effects are not due to HSP90 inhibition. Conclusion We uncover a previously unknown role for HSP90 N‐terminal inhibitors in promoting MORC2 degradation in a HSP90‐indepentent manner and support the potential application of these inhibitors for treating MORC2‐overexpressing tumors, even those with low or absent HSP90 expression. These results also provide new clue for further design of novel small‐molecule inhibitors of MORC2 for anticancer therapeutic application.

Photodynamic therapy (PDT) is a promising non-invasive therapeutic modality that has been proposed for treating prostate cancer, but the procedure is associated with limited efficacy, tumor recurrence and photo-toxicity. In the present study, we proposed to develop a novel multifunctional nano-platform for targeted delivery of heat, reactive oxygen species (ROS) and heat shock protein 90 (Hsp90) inhibitor simultaneously for combination therapy against prostate cancer. This new nano-platform combines two newly developed entities: 1) a unique organic and biocompatible nanoporphyrin-based drug delivery system that can generate efficient heat and ROS simultaneously with light activation at the tumor sites for dual-modal photothermal- and photodynamic- therapy (PTT/PDT), and 2) new nano-formulations of Hsp90 inhibitors that can decrease the levels of pro-survival and angiogenic signaling molecules induced by phototherapy, therefore, further sensitizing cancer cells to phototherapy. Furthermore, the nanoparticles have activatable near infrared (NIR) fluorescence for optical imaging to conveniently monitor the real-time drug delivery in both subcutaneous and orthotopic mouse models bearing prostate cancer xenograft. This novel multifunctional nano-platform has great potential to improve the care of prostate cancer patients through targeted combination therapy.

• HSP90 inhibitor SNX-5422 with carboplatin/paclitaxel is safe in advanced lung cancer. • The preliminary efficacy of this combination is encouraging in an enriched subpopulation of lung cancers with oncogenic drivers. • Future development of current and next-generation HSP90 inhibitors should consider the inclusion of oncogene-driven lung cancers. Single-agent heat shock protein 90 (HSP90) inhibition has demonstrated activity in oncogene-driven non-small cell and small cell lung cancers. SNX-5422 is an oral HSP90 inhibitor with increased activity in vitro with the addition of carboplatin and paclitaxel. Therefore, we conducted a phase 1, open-label, multicenter study to evaluate SNX-5422, carboplatin and paclitaxel followed by SNX-5422 maintenance in patients with advanced lung cancers. In part 1 (3 + 3 dose escalation), SNX-5422 (50/75/100-mg/m2) was dosed every other day (qod) for 21 days (28-day cycle) for ≤4 cycles; carboplatin (AUC 5)-paclitaxel (175 mg/m2) was administered once every 3 weeks for ≤6 courses. In part 2 (maintenance), subjects who achieved at least stable disease in part 1 received 100 mg/m2 SNX-5422 monotherapy qod for 21 days (28-day cycle). Twenty-three patients with advanced non-small cell lung cancer (NSCLC, n = 20) and small cell lung cancer (SCLC, n = 3) were enrolled. The median age was 60 years and 61% (n = 14/23) had ≥1 prior treatment regimens. The maximum tolerated dose of SNX-5422 was 100 mg/m2 qod in combination with carboplatin-paclitaxel. The most common treatment-related grade 3/4 adverse events (part 1/part 2) were diarrhea (26%/15%) and nausea (9%/0%). In response-evaluable patients with NSCLC, 33% (6/18) had a partial response, 56% (10/18) stable disease, and 11% (2/18) progressive disease. Patients who remained on single-agent SNX-5422 maintenance therapy ≥2 months (n = 9) had cancers enriched for oncogenic drivers (n = 3 KRAS mutation, n = 1 EGFR exon 20 mutation, n = 1 HER2 mutation, and n = 1 RET fusion). The triplet combination of SNX-5422, carboplatin and paclitaxel followed by maintenance SNX-5422 therapy was well-tolerated and showed anti-tumor activity. Cancers for which disease control on single-agent SNX-5422 maintenance was observed were enriched for oncogene-driven NSCLCs. [ABSTRACT FROM AUTHOR]

Objective To investigate the effect of HSP90 inhibitor on glycolysis and apoptosis in mouse hepatocarcinoma cells, and to explore its underlying mechanism. Methods Examine the level of lactate and ATP in mouse hepatoma cell line H22 treated with CORT, GR antagonist RU486 and HSP90 inhibitor 17-AAG; Evaluate the apoptosis level of H22 cells after CORT or various concentrations of 17-AAG treatment; H22 cells were treated with CORT, RU486 and 17-AAG respectively, and then the expression of GR and PI3K/Akt-related proteins was determined by Western blot. Results Compared with the control group, CORT promoted GR nuclear translocation, while inhibited after RU486 treatment. Compared with CORT treatment alone, CORT and 17-AAG co-treatment could weaken the promotion of GR nuclear translocation by CORT(P＜0.05); The level of lactate and ATP was increased significantly after CORT treatment (P＜0.05). After co-treatment with 17-AAG, this effect was inhibited (P＜0.05).And the level of lactate and ATP was decreased by 24% and 17% respectively; Compared with the control group, 17-AAG could significantly increase the total apoptosis rate of H22 cells in a dose-dependent manner(P＜0.05); Compared with the control group, the protein expression of pAkt increased after CORT treatment, while decreased significantly after co-treatment with 17-AAG (P＜0.05). Conclusions HSP90 inhibitor 17-AAG can inhibit GR nuclear translocation, thereby inhibit glycolysis and promote apoptosis of hepatocarcinoma cells, which is potentially regulated by PI3K/Akt pathway.

Abstract Background The benefit of inducing cellular senescence as a tumor suppressive strategy remains questionable due to the senescence-associated secretory phenotype. Hence, studies and development of senolytic compounds that induce cell death in senescent cells have recently emerged. Senescent cells are hypothesized to exhibit different upregulated pro-survival/anti-apoptotic networks depending on the senescent inducers. This might limit the effect of a particular senolytic compound that targets rather only a specific pathway. Interestingly, cellular senescence in prostate cancer (PCa) cells can be induced by either androgen receptor (AR) agonists at supraphysiological androgen level (SAL) used in bipolar androgen therapy or by AR antagonists. This challenges to define ligand-specific senolytic compounds. Results Here, we first induced cellular senescence by treating androgen-sensitive PCa LNCaP cells with either SAL or the AR antagonist Enzalutamide (ENZ). Subsequently, cells were incubated with the HSP90 inhibitor Ganetespib (GT), the Bcl-2 family inhibitor ABT263, or the Akt inhibitor MK2206 to analyze senolysis. GT and ABT263 are known senolytic compounds. We observed that GT exhibits senolytic activity specifically in SAL-pretreated PCa cells. Mechanistically, GT treatment results in reduction of AR, Akt, and phospho-S6 (p-S6) protein levels. Surprisingly, ABT263 lacks senolytic effect in both AR agonist- and antagonist-pretreated cells. ABT263 treatment does not affect AR, Akt, or S6 protein levels. Treatment with MK2206 does not reduce AR protein level and, as expected, potently inhibits Akt phosphorylation. However, ENZ-induced cellular senescent cells undergo apoptosis by MK2206, whereas SAL-treated cells are resistant. In line with this, we reveal that the pro-survival p-S6 level is higher in SAL-induced cellular senescent PCa cells compared to ENZ-treated cells. These data indicate a difference in the agonist- or antagonist-induced cellular senescence and suggest a novel role of MK2206 as a senolytic agent preferentially for AR antagonist-treated cells. Conclusion Taken together, our data suggest that both AR agonist and antagonist induce cellular senescence but differentially upregulate a pro-survival signaling which preferentially sensitize androgen-sensitive PCa LNCaP cells to a specific senolytic compound.

Background: Photothermal therapy (PTT) has been extensively investigated as a tumor-localizing therapeutic modality for neoplastic disorders. However, the hyperthermia effect of PTT is greatly restricted by the thermoresistance of tumor cells. Particularly, the compensatory expression of heat shock protein 90 (HSP90) has been found to significantly accelerate the thermal tolerance of tumor cells. Thus, a combination of HSP90 inhibitor and photothermal photosensitizer is expected to significantly enhance antitumor efficacy of PTT through hyperthermia sensitization. However, it remains challenging to precisely co-deliver two or more drugs into tumors. Methods: A carrier-free co-delivery nanoassembly of gambogic acid (GA, a HSP90 inhibitor) and DiR is ingeniously fabricated based on a facile and precise molecular co-assembly technique. The assembly mechanisms, photothermal conversion efficiency, laser-triggered drug release, cellular uptake, synergistic cytotoxicity of the nanoassembly are investigated in vitro. Furthermore, the pharmacokinetics, biodistribution and self-enhanced PTT efficacy were explored in vivo. Results: The nanoassembly presents multiple advantages throughout the whole drug delivery process, including carrier-free fabrication with good reproducibility, high drug co-loading efficiency with convenient dose adjustment, synchronous co-delivery of DiR and GA with long systemic circulation, as well as self-tracing tumor accumulation with efficient photothermal conversion. As expected, HSP90 inhibition-augmented PTT is observed in a 4T1 tumor BALB/c mice xenograft model. Conclusion: Our study provides a novel and facile dual-drug co-assembly strategy for self-sensitized cancer therapy. [ABSTRACT FROM AUTHOR]

Heat shock proteins (Hsps) have garnered special attention in cancer therapy as molecular chaperones with regulatory/mediatory effects on folding, maintenance/stability, maturation, and conformation of proteins as well as their effects on prevention of protein aggregation. Hsp90 ensures the stability of various client proteins needed for the growth of cells or the survival of tumor cells; therefore, they are overexpressed in tumor cells and play key roles in carcinogenesis. Accordingly, Hsp90 inhibitors are recognized as attractive therapeutic agents for investigations pertaining to tumor suppression. Natural Hsp90 inhibitors comprising geldanamycin (GM), reclaimed analogs of GM including 17-AAG and DMAG, and radicicol, a natural macrocyclic antifungal, are among the first potent Hsp90 inhibitors. Herein, recently synthesized heterocyclic compounds recognized as potent Hsp90 inhibitors are reviewed along with the anticancer effects of heterocyclic compounds, comprising purine, pyrazole, triazine, quinolines, coumarin, and isoxazoles molecules.

Liman Wang,1–3,* Yingjuan Fan,1,* Hanhao Mei,1 Yang Liu,1 Lianru Zhang,4 Jianhua Xu,1 Xuhui Huang2,3 1Institute of Materia Medica, School of Pharmacy, Fuijan Provincial Key Laboratory of Natural Medicine Pharmacology, Fujian Medical University, Fuzhou 350122, People’s Republic of China; 2Department of Pharmacy, Fujian Provincial Hospital Jinshan Branch/Fujian Provincial Hospital South Branch, Fuzhou 350028, People’s Republic of China; 3Provincial Clinical Medical College of Fujian Medical University, Fuzhou 350000, People’s Republic of China; 4State Key Laboratory of Cellular Stress Biology, School of Life Science, Xiamen University, Xiamen 361005, People’s Republic of China*These authors contributed equally to this workCorrespondence: Jianhua XuInstitute of Materia Medica, School of Pharmacy, Fuijan Provincial Key Laboratory of Natural Medicine Pharmacology, Fujian Medical University, No. 1, Xue Fu Bei Road, University Town, Fuzhou 350122, People’s Republic of ChinaTel/Fax +86 133 3844 0289Email xjh@fjmu.edu.cnPurpose: Inhibition of heat shock protein 90 (Hsp90) can lead to degradation of multiple client proteins, which are involved in tumor progression. Elevated Hsp90 expression has been linked to poor prognosis in patients with non-small cell lung cancer (NSCLC). Discovery of effective drug is a promising strategy to improve patient survival. This study aims to investigate the synergistic antitumor mechanism of C086 combined with gefitinib in NSCLC cells in vitro.Methods: The binding of C086, gefitinib, and the combinations to Hsp90 was characterized by fluorescence quenching experiments. The inhibition of A549 or NCI-H1975 cell proliferation and apoptosis by C086 and gefitinib as a single agent or in combinations were performed using CFSE staining assays, AnnexinV–APC/PI and Western blot.Results: C086 alone or with gefitinib reduces proliferation and increases proapoptotic caspase activation of both wild-type and mutation NSCLC, with NCI-H1975 cells showing much greater sensitivity to C086 and the combinations than A549 cells. The combination of C086 and gefitinib showed synergistic reduction of EGFR expression and the downstream PI3K/Akt and Ras-Raf-Erk pathways enhanced suppression of Erk signaling.Conclusion: C086 combined gefitinib has a good synergistic antitumor effect in vitro. Therefore, the combination of C086 and gefitinib may provide a new theoretical basis and ideas for the treatment of NSCLC patients.Keywords: C086, Hsp90 inhibitor, EGFR, non-small cell lung cancer

Abstract Heat shock protein 90 (Hsp90) is a potential oncogenic target. However, Hsp90 inhibitors in clinical trial induce heat shock response, resulting in drug resistance and inefficiency. In this study, we designed and synthesized a series of novel triazine derivatives (A1‐26, B1‐13, C1‐23) as Hsp90 inhibitors. Compound A14 directly bound to Hsp90 in a different manner from traditional Hsp90 inhibitors, and degraded client proteins, but did not induce the concomitant activation of Hsp72. Importantly, A14 exhibited the most potent anti‐proliferation ability by inducing autophagy, with the IC50 values of 0.1 μM and 0.4 μM in A549 and SK‐BR‐3 cell lines, respectively. The in vivo study demonstrated that A14 could induce autophagy and degrade Hsp90 client proteins in tumor tissues, and exhibit anti‐tumor activity in A549 lung cancer xenografts. Therefore, the compound A14 with potent antitumor activity and unique pharmacological characteristics is a novel Hsp90 inhibitor for developing anticancer agent without heat shock response.

Topo II and Hsp90 are promising targets. In this study, we first verified the structural similarities between Topo IIα ATPase and Hsp90α N−ATPase. Subsequently, 720 compounds from the Food and Drug Administration (FDA) drug library and kinase library were screened using the malachite green phosphate combination with the Topo II-mediated DNA relaxation and MTT assays. Subsequently, the antimalarial drug quinacrine was found to be a potential dual−target inhibitor of Topo II and Hsp90. Mechanistic studies showed that quinacrine could specifically bind to the Topo IIα ATPase domain and inhibit the activity of Topo IIα ATPase without impacting DNA cleavage. Furthermore, our study revealed that quinacrine could bind Hsp90 N−ATPase and inhibit Hsp90 activity. Significantly, quinacrine has broad antiproliferation activity and remains sensitive to the multidrug−resistant cell line MCF−7/ADR and the atypical drug−resistant tumor cell line HL−60/MX2. Our study identified quinacrine as a potential dual−target inhibitor of Topo II and Hsp90, depending on the ATP−binding domain, positioning it as a hit compound for further structural modification.

Mitochondria-targeted mild-temperature photothermal therapy (MT-PTT) is a promising strategy that can maximize anticancer effects and reduce adverse reactions. Here, a novel photosensitizer with mitochondrial targeting based on IR780 iodide and heat shock protein 90 inhibitor (BIIB021), which can passively accumulate in MCF-7 cells and achieve effective MT-PTT effect is synthesized. The prepared PEG-IR780-BIIB021 nano-micelles possess considerable biocompatibility and biological stability, with an encapsulation efficiency of about 84% for BIIB021. They can selectively enrich in mitochondria, and release BIIB021 after NIR irradiation to reduce cell tolerance to heat, thereby reducing the mitochondrial membrane potential and rapidly affecting key intrinsic apoptotic factors (Cyt-C, Caspase-9, Bcl-2 and Bax) to achieve the effect of MT-PTT. It is believed that mitochondria-targeted MT-PTT generated by the PEG-IR780-BIIB021 nano-micelles is a promising therapeutic strategy in clinical practice. [ABSTRACT FROM AUTHOR]

Introduction: Xeroderma pigmentosum complementation group C (XPC) protein is an important DNA damage recognition factor involved in nucleotide excision repair and regulation of non-small-cell lung cancer (NSCLC) cell proliferation and viability. 17-Allylamino-17-demethoxygeldanamycin (17-AAG) blocks ATP binding to heat shock protein 90 (Hsp90), resulting in destabilization of Hsp90-client protein complexes. Vascular endothelial growth factor (VEGF) is a potent angiogenic growth factor expressed by many types of tumors. Bevacizumab (Avastin) is a humanized monoclonal antibody against human VEGF used as an antiangiogenesis agent in the therapy of many cancers, proving successful in increasing objective tumor response rate and prolonging overall survival in NSCLC patients. Methods: After the bevacizumab and/or 17-AAG treatment, the expressions of XPC mRNA were determined by quantitative real-time PCR analysis. Protein levels of XPC and phospho-AKT were determined by Western blot analysis. We used specific XPC small interfering RNA and PI3K inhibitor (LY294002) to examine the role of the AKT-XPC signal in regulating the chemosensitivity of bevacizumab and 17-AAG. Cell viability was assessed by the MTS assay and trypan blue exclusion assay. Results: In this study, bevacizumab decreased XPC expression in human lung squamous cell carcinoma H520 and H1703 cells via AKT inactivation. Enhancement of AKT activity by transfection with constitutively active AKT vectors increased XPC expression and cell survival after treatment with bevacizumab. In addition, 17-AAG synergistically enhanced bevacizumab-induced cytotoxicity and cell growth inhibition in H520 and H1703 cells, associated with downregulation of XPC expression and inactivation of AKT. Discussion/Conclusion: Together, these results may provide a rationale to combine bevacizumab with Hsp90 inhibitors in future to enhance therapeutic effects for lung cancer. [ABSTRACT FROM AUTHOR]