Heat Shock Protein 90 Inhibitor Research Articles

Plant-Based HSP90 Inhibitors in Breast Cancer Models: A Systematic Review.

Breast cancer, the most invasive cancer in women globally, necessitates novel treatments due to prevailing limitations of therapeutics. Search of news anticancer targets is more necessary than ever to tackle this pathology. Heat-Shock Protein 90 (HSP90), a chaperone protein, is implicated in breast cancer pathogenesis, rendering it an appealing target. Looking for alternative approach such as Plant-based compounds and natural HSP90 inhibitors offer promising prospects for innovative therapeutic strategies. This study aims to identify plant-based compounds with anticancer effects on breast cancer models and elucidate their mechanism of action in inhibiting the HSP90 protein. A systematic review was conducted and completed in January 2024 and included in vitro, in vivo, and in silico studies that investigated the effectiveness of plant-based HSP90 inhibitors tested on breast cancer models. Eleven studies were included in the review. Six plants and 24 compounds from six different classes were identified and proved to be effective against HSP90 in breast cancer models. The studied plant extracts showed a dose- and time-dependent decrease in cell viability. Variable IC50 values showed antiproliferative effects, with the plant Tubocapsicum anomalum demonstrating the lowest value. Withanolides was the most studied class. Fennel, Trianthema portulacastrum, and Spatholobus suberectus extracts were shown to inhibit tumor growth and angiogenesis and modulate HSP90 expression as well as its cochaperone interactions in breast cancer mouse models. The identified plant extracts and compounds were proven effective against HSP90 in breast cancer models, and this inhibition showed promising effects on breast cancer biology. Collectively, these results urge the need of further studies to better understand the mechanism of action of HSP90 inhibitors using comparable methods for preclinical observations.

The Role of HSP90 and TRAP1 Targets on Treatment in Hepatocellular Carcinoma.

Hepatocellular Carcinoma (HCC) is the predominant form of liver cancer and arises due to dysregulation of the cell cycle control machinery. Heat Shock Protein 90 (HSP90) and mitochondrial HSP90, also referred to as TRAP1 are important critical chaperone target receptors for early diagnosis and targeting HCC. Both HSP90 and TRAP1 expression was found to be higher in HCC patients. Hence, the importance of HSP90 and TRAP1 inhibitors mechanism and mitochondrial targeted delivery of those inhibitors function is widely studied. This review also focuses on importance of protein-protein interactions of HSP90 and TRAP1 targets and association of its interacting proteins in various pathways of HCC. To further elucidate the mechanism, systems biology approaches and computational biology approach studies are well explored in the association of inhibition of herbal plant molecules with HSP90 and its mitochondrial type in HCC.

Targeted delivery of HSP90 inhibitors for efficient therapy of CD44-positive acute myeloid leukemia and solid tumor-colon cancer

Heat shock protein 90 (HSP90) is overexpressed in numerous cancers, promotes the maturation of numerous oncoproteins and facilitates cancer cell growth. Certain HSP90 inhibitors have entered clinical trials. Although less than satisfactory clinical effects or insurmountable toxicity have compelled these trials to be terminated or postponed, these results of preclinical and clinical studies demonstrated that the prospects of targeting therapeutic strategies involving HSP90 inhibitors deserve enough attention. Nanoparticulate-based drug delivery systems have been generally supposed as one of the most promising formulations especially for targeting strategies. However, so far, no active targeting nano-formulations have succeeded in clinical translation, mainly due to complicated preparation, complex formulations leading to difficult industrialization, incomplete biocompatibility or nontoxicity. In this study, HSP90 and CD44-targeted A6 peptide functionalized biomimetic nanoparticles (A6-NP) was designed and various degrees of A6-modification on nanoparticles were fabricated to evaluate targeting ability and anticancer efficiency. With no excipients, the hydrophobic HSP90 inhibitor G2111 and A6-conjugated human serum albumin could self-assemble into nanoparticles with a uniform particle size of approximately 200 nm, easy fabrication, well biocompatibility and avoidance of hepatotoxicity. Besides, G2111 encapsulated in A6-NP was only released less than 5% in 12 h, which may avoid off-target cell toxicity before entering into cancer cells. A6 peptide modification could significantly enhance uptake within a short time. Moreover, A6-NP continues to exert the broad anticancer spectrum of Hsp90 inhibitors and displays remarkable targeting ability and anticancer efficacy both in hematological malignancies and solid tumors (with colon tumors as the model cancer) both in vitro and in vivo. Overall, A6-NP, as a simple, biomimetic and active dual-targeting (CD44 and HSP90) nanomedicine, displays high potential for clinical translation.

Dynamics of clonal hematopoiesis under DNA-damaging treatment in patients with ovarian cancer.

Clonal hematopoiesis (CH) driven by mutations in the DNA damage response (DDR) pathway is frequent in patients with cancer and is associated with a higher risk of therapy-related myeloid neoplasms (t-MNs). Here, we analyzed 423 serial whole blood and plasma samples from 103 patients with relapsed high-grade ovarian cancer receiving carboplatin, poly(ADP-ribose) polymerase inhibitor (PARPi) and heat shock protein 90 inhibitor (HSP90i) treatment within the phase II EUDARIO trial using error-corrected sequencing of 72 genes. DDR-driven CH was detected in 35% of patients and was associated with longer duration of prior PARPi treatment. TP53- and PPM1D-mutated clones exhibited substantially higher clonal expansion rates than DNMT3A- or TET2-mutated clones during treatment. Expansion of DDR clones correlated with HSP90i exposure across the three study arms and was partially abrogated by the presence of germline mutations related to homologous recombination deficiency. Single-cell DNA sequencing of selected samples revealed clonal exclusivity of DDR mutations, and identified DDR-mutated clones as the origin of t-MN in two investigated cases. Together, these results provide unique insights into the architecture and the preferential selection of DDR-mutated hematopoietic clones under intense DNA-damaging treatment. Specifically, PARPi and HSP90i therapies pose an independent risk for the expansion of DDR-CH in a dose-dependent manner.

Combination therapy involving HSP90 inhibitors for combating cancer: an overview of clinical and preclinical progress.

The molecular chaperone heat shock protein 90 (HSP90) regulates multiple crucial signalling pathways in cancer by driving the maturation of key signalling components, thereby playing a crucial role in tumorigenesis and drug resistance in cancer. Inhibition of HSP90 results in metastable conformational collapse of its client proteins and their proteasomal degradation. Considerable efforts have been devoted to the development of small-molecule inhibitors targeting HSP90, and more than 20 inhibitors have been evaluated in clinical trials for cancer therapy. However, owing to disadvantages such as organ toxicity and drug resistance, only one HSP90 inhibitor has been approved for use in clinical settings. In recent years, HSP90 inhibitors used in combination with other anti-cancer therapies have shown remarkable potential in the treatment of cancer. HSP90 inhibitors work synergistically with various anti-cancer therapies, including chemotherapy, targeted therapy, radiation therapy and immunotherapy. HSP90 inhibitors can improve the pharmacological effects of the above-mentioned therapies and reduce treatment resistance. This review provides an overview of the use of combination therapy with HSP90 inhibitors and other anti-cancer therapies in clinical and preclinical studies reported in the past decade and summarises design strategies and prospects for these combination therapies. Altogether, this review provides a theoretical basis for further research and application of these combination therapies in the treatment of cancer.

Gkongensin A, an HSP90β inhibitor, improves hyperlipidemia, hepatic steatosis, and insulin resistance

The prevalence of obesity and its primary associated comorbidities, such as type 2 diabetes and fatty liver disease, has reached epidemic proportions, with no successful treatment available at present. Heat shock protein 90 (HSP90), a crucial chaperone, plays a key role in de novo lipogenesis (DNL) by stabilizing and maintaining sterol regulatory element binding protein (SREBP) activity. Kongensin A (KA), derived from Croton kongensis, inhibits RIP3-mediated necrosis, showing promise as an anti-necrotic and anti-inflammatory agent. It is not yet clear if KA, acting as an HSP90 inhibitor, can enhance hyperlipidemia, hepatic steatosis, and insulin resistance in obese individuals by controlling lipid metabolism. In this study, we first found that KA can potentially decrease lipid content at the cellular level. C57BL/6J mice were given a high-fat diet (HFD) and received KA and lovastatin through oral administration for 7 weeks. KA improved hyperlipidemia, fatty liver, and insulin resistance, as well as reduced body weight in diet-induced obese (DIO) mice, with no significant alteration in food intake. In vitro, KA suppressed DNL and reduced the amounts of mSREBPs. KA promoted mSREBP degradation via the FBW7-mediated ubiquitin-proteasome pathway. KA decreased the level of p-Akt Ser308, and p-GSK3β Ser9 by inhibiting the interaction between HSP90β and Akt. Overall, KA enhanced hyperlipidemia, hepatic steatosis, and insulin resistance by blocking SREBP activity, thereby impacting the FBW7-controlled ubiquitin-proteasome pathway.

Abstract 7632: Final survival outcomes and post-hoc tumor gene expression pathway analyses of complete responders from a phase Ib clinical trial of HSP90 inhibitor onalespib and paclitaxel in patients with advanced triple-negative breast cancer

Abstract 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, therefore, it was hypothesized that the potent HSP90 inhibitor onalespib could improve paclitaxel efficacy. As TNBCs are a heterogenous population of tumors, it is important to establish biomarkers of response to this treatment combination. Methods: Patients with TNBC were treated with intravenous (IV) paclitaxel and IV onalespib at doses ranging from 120 mg/m2 to 260 mg/m2 on days 1, 8, and 15 of a 28-day cycle utilizing a standard 3+3 design. The primary objectives were to determine dose-limiting toxicities and maximum tolerated dose. Secondary objectives included determination of overall response rate (ORR), duration of response (DOR), and progression-free survival (PFS). Retrospectively, archival tumor tissue was obtained from study patients and processed for RNA expression analysis by NanoString nCounter platform with the Breast Cancer 360 panel. Post-hoc gene expression analysis was performed through Qiagen Ingenuity Pathway Analysis (IPA). Linear models were employed to detect differential expression between conditions while considering cartridge effect. Results: 31 patients were enrolled in this study, of which 90% received prior taxane therapy. The established recommended phase II dose was 260 mg/m2 onalespib when given with 80 mg/m2 paclitaxel. ORR was 20%, median DOR was 5.6 months. Three patients achieved complete responses (CR), all of whom had received prior taxane therapy. Nanostring profiling analysis revealed that patients who had a CR to treatment expressed higher levels of several breast cancer-associated genes also known to be dependent upon HSP90 activity compared to patients with progressive disease (PD) as their best treatment response. These genes include FGFR4, JAK2, PIK3R1, TGFB3, and TGFBR2 (all p<0.05). Tumor genes overexpressed in patients with PD versus CR included IRF6, MMP7, and KRT17 (all p<0.01). Additionally, IPA showed patients with CR to have substantial upregulation of PD-1, PD-L1, CTLA-4, p53, HER2, and cyclin/cell cycle regulatory signaling pathways compared to patients with PD (all p<0.01). Conclusions: Combination treatment with onalespib and paclitaxel had an acceptable toxicity profile and showed anti-tumor activity in patients with advanced TNBC. Gene expression analysis of patient tumor samples suggest that TNBCs with greater activation of immune checkpoint pathways and those with proteins dependent on HSP90 activity, including p53 and HER2, may be more susceptible to HSP90 inhibition. ClinicalTrials.gov study identification: NCT02474173 Citation Format: Dionisia Marie Quiroga, Himanshu Savardekar, Emily Schwarz, Nicole O. Williams, Courtney Johnson, Adam Brufsky, Mara Chambers, Saveri Bhattacharya, Maria Patterson, Sagar D. Sardesai, Daniel Stover, Maryam Lustberg, Anne Noonan, Mathew Cherian, Darlene M. Bystry, Kasey Hill, Min Chen, Mitch A. Phelps, Julie Stephens, Lianbo Yu, Bhuvaneswari Ramaswamy, Robert Wesolowski, William E. Carson. Final survival outcomes and post-hoc tumor gene expression pathway analyses of complete responders from a phase Ib clinical trial of HSP90 inhibitor onalespib and paclitaxel in patients with advanced triple-negative breast cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 7632.

HSP90 inhibition suppresses tumor glycolytic flux to potentiate the therapeutic efficacy of radiotherapy for head and neck cancer.

Glycolytic metabolism may account for antitumor immunity failure. Pyruvate kinase M2 (PKM2) and platelet phosphofructokinase (PFKP), two key enzymes involved in the glycolytic pathway, are hyperactivated in head and neck squamous cell carcinoma (HNSCC). Using ganetespib as a drug model for heat shock protein 90 (HSP90) inhibition and combining results from clinical trials and animal treatment, we demonstrated that HSP90 inhibition leads to a blockade of glycolytic flux in HNSCC cells by simultaneously suppressing PKM2 and PFKP at both the transcriptional and posttranslational levels. Down-regulation of tumor glycolysis facilitates tumor infiltration of cytotoxic T cells via suppression of glycolysis-dependent interleukin-8 signaling. The addition of ganetespib to radiation attenuates radiation-induced up-regulation of PKM2 and PFKP and potentiates T cell-mediated antitumor immunity, resulting in a more potent antitumor effect than either treatment alone, providing a molecular basis for exploring the combination of HSP90 inhibitors with radiotherapy to improve outcomes for patients with HNSCC.

HSP70 Is a Critical Regulator of HSP90 Inhibitor's Effectiveness in Preventing HCl-Induced Chronic Lung Injury and Pulmonary Fibrosis.

Exposure to hydrochloric acid (HCl) can provoke acute and chronic lung injury. Because of its extensive production for industrial use, frequent accidental exposures occur, making HCl one of the top five chemicals causing inhalation injuries. There are no Food and Drug Administration (FDA)-approved treatments for HCl exposure. Heat shock protein 90 (HSP90) inhibitors modulate transforming growth factor-β (TGF-β) signaling and the development of chemical-induced pulmonary fibrosis. However, little is known on the role of Heat Shock Protein 70 (HSP70) during injury and treatment with HSP90 inhibitors. We hypothesized that administration of geranylgeranyl-acetone (GGA), an HSP70 inducer, or gefitinib (GFT), an HSP70 suppressant, alone or in combination with the HSP90 inhibitor, TAS-116, would improve or worsen, respectively, HCl-induced chronic lung injury in vivo and endothelial barrier dysfunction in vitro. GGA, alone, improved HCl-induced human lung microvascular endothelial cells (HLMVEC) barrier dysfunction and, in combination with TAS-116, improved the protective effect of TAS-116. In mice, GGA reduced HCl toxicity and while TAS-116 alone blocked HCl-induced chronic lung injury, co-administration with GGA, resulted in further improvement. Conversely, GFT potentiated HCl-induced barrier dysfunction and impaired the antidotal effects of TAS-116. We conclude that combined treatments with HSP90 inhibitors and HSP70 inducers may represent a novel therapeutic approach to manage HCl-induced chronic lung injury and pulmonary fibrosis.

Molecular mechanism of anticancer effect of heat shock protein 90 inhibitor BIIB021 in human bladder cancer cell line.

Bladder cancer is a type of urologic malignancy that exhibits significant morbidity, mortality, and treatment costs. Inhibition of heat shock protein 90 (HSP90) activity has been a promising pharmacological strategy for blocking of bladder cancer pathogenesis. BIIB021 is a next-generation HSP90 inhibitor which interrupts ATP hydrolysis process of HSP90 and inhibits the stabilization and correct folding of client proteins. In current study, we aimed to investigate the molecular mechanism of the anticancer activity of BIIB021 in human bladder cancer T24 cells. Our results revealed that nanomolar concentration of BIIB021 decreased viability of T24 cell. BIIB021 downregulated HSP90 expression in T24 cells and inhibited the refolding activity of luciferase in the presence of T24 cell lysate. PCR array data indicated a significant alteration in transcript levels of cancer-related genes involved in metastases, apoptotic cell death, cell cycle, cellular senescence, DNA damage and repair mechanisms, epithelial-to-mesenchymal transition, hypoxia, telomeres and telomerase, and cancer metabolism pathways in T24 cells. All findings hypothesize that BIIB021 could exhibit as effective HSP90 inhibitor in the future for treatment of bladder cancer patients.

Drug screening identified that handelin inhibits feline calicivirus infection by inhibiting HSP70 expression in vitro.

Feline calicivirus (FCV) is considered one of the major pathogens of cats worldwide and causes upper respiratory tract disease in all cats. In some cats, infection is by a highly virulent strain of FCV (vs.-FCV), which can cause severe and fatal systemic disease symptoms. At present, few antiviral drugs are approved for clinical treatment against FCV. Therefore, there is an imminent need for effective FCV antiviral agents. Here, we used observed a cytopathic effect (CPE) assay to screen 1746 traditional Chinese medicine monomer compounds and found one that can effectively inhibit FCV replication, namely, handelin, with an effective concentration (EC50) value of approximately 2.5 µM. Further study showed that handelin inhibits FCV replication via interference with heat shock protein 70 (HSP70), which is a crucial host factor and plays a positive role in regulating viral replication. Moreover, handelin and HSP70 inhibitors have broad-spectrum antiviral activity. These findings indicate that handelin is a potential candidate for the treatment of FCV infection and that HSP70 may be an important drug target.

Evaluation of combined use of hsp90 inhibitor mpc-3100 and traditional cancer drug 5-fu on liver cancer cell lines

Hepatocellular carcinoma (HCC), which constitutes an important part of the global cancer burden, poses an important problem in the field of medicine. Combination therapy targets multiple mechanisms simultaneously using different therapeutic agents together. Heat shock protein 90 (HSP90) inhibitors are emerging as interesting targets in this area, since they play a vital role in the control of cellular processes and impact malignant cell survival and resistance mechanisms. This study evaluated the combined effect of the HSP90 inhibitor MPC-3100 and the traditional chemotherapy drug 5-fluorouracil (5-FU) on HCC. MTT assay was performed to evaluate the individual and combined cytotoxic effects of 5-FU and MPC-3100 on HUH-7 and HepG2 liver cancer cell lines. To assess the effectiveness of combination therapy, the Chou and Talalay method was applied. Both 5-FU and MPC-3100 and 5-FU+ MPC-3100 exhibited dose- and time-dependent cytotoxic effects. Combined administration of the two drugs showed an antagonistic impact on the cell lines. The findings demonstrated that combining 5-FU with MPC-3100 was less effective in inducing cytotoxicity in liver cancer cell lines compared to the use of each drug separately. In this context, the combination of these two drugs in liver cancer is not an appropriate strategy for effective treatment. Current research findings will help design more effective and targeted therapies for HCC and other cancers.

Synthesis and evaluation of the antitumor activity of 2-amino-4-tetrahydroindazole-substituted benzamide derivatives as HSP90 inhibitors

A new series of 2-cycloalkylamino-4–3,6,6-trimethyl-4-oxo-4,5,6,7-tetrahydro-1H-indazol-1-yl benzamide analogs was synthesized and evaluated for their in vitro antineoplastic activity. These compounds are analogs of 2-(4-hydroxy-cyclohexylamino)-4-(3,6,6-trimethyl-4-oxo-4,5,6,7-tetrahydro-1H-indazol-1-yl) benzamide (AT533), which has been previously identified as a potent inhibitor of heat shock protein 90 (HSP90). These newly synthesized analogs showed moderate-to-excellent anti-cancer activity against Eca109, A549, and MDA-MB-231 human carcinoma cells. In particular, JD-10, JD-13, and JD-14 demonstrated more potent antineoplastic effects than AT533 in tumor cells. Molecular docking studies indicated that these novel derivatives bind to the ATP-binding pocket of HSP90.

HSP90 Inhibition Attenuated Isoflurane-Induced Neurotoxicity in Mice and Human Neuroglioma Cells.

Isoflurane, a widely used inhalation anesthetic in clinical practice, is associated with an increased risk of neuronal injury. Heat shock protein 90 (HSP90) plays a crucial role in maintaining neuronal homeostasis under stress conditions; however, its role during isoflurane exposure remains poorly understood. In this study, we aimed to investigate the protective effects of HSP90 inhibition and explore the regulatory mechanisms underlying these effects during isoflurane exposure. We found that the HSP90 inhibitor 17-N-allylamino-17-demethoxygeldanamycin (17 AAG) has great protective effects in mitigating isoflurane-induced ferroptosis of mouse hippocampus and cultured neuronal cells. We focused on the activity of the crucial protein GPX4 in ferroptosis and found that 17 AAG exerted protective effects, preserving the physiological GPX4 activity under isoflurane exposure; further, 17 AAG restored the protein level of GPX4. Further, we observed that the chaperone-mediated autophagy (CMA) pathway was activated; 17 AAG also mediated GPX4 degradation under isoflurane exposure. Additionally, it interfered with the formation of complexes between HSP90 and Lamp-2a, inhibiting CMA activity, followed by the blockade of GPX4 degradation, further affecting the isoflurane-induced ferroptosis. Based on these findings, we proposed HSP90 inhibition as a protective mechanism against isoflurane-induced ferroptosis in neurons.

EXTH-60. OVERCOMING THE LEPTOMENINGEAL SEEDING OF MEDULLOBLASTOMA BY TARGETING HSP70

Abstract Purpose The development of leptomeningeal seeding (LMS) through the cerebrospinal fluid (CSF) is a common in medulloblastoma (MB) and a major cause of treatment failure. The mechanism of MB LMS remains unclear and effective treatment options are urgently required. This study aimed to discover molecules that can specifically target seeding cells by making a cellular model of MB LMS and analyzing their specific genetic and functional characteristics. METHODS: By repeated transplantation, separation, culture, seeding and non-seeding MB cells were isolated. The cellular characteristics of each group were compared and differentially expressed genes (DEGs) were determined through gene expression profiling. The therapeutic effect of the selected inhibitor on the selected protein was tested in vitro and in vivo. RESULTS: We separated seeding and non-seeding cells triply, with the DEGs analysis indicating that heat shock protein 70 (HSP70) was in the highest rank in the expression profile of the seeding cells, and pathway enrichment analysis revealed that the metabolism was the main pathway enriched in seeding cells. The proliferation of seeding cells (S3) was slower than that of non-seeding cells (N3), but there was no significant difference in viability. Notably, the wound-healing of S3 was delayed, but the adhesion ability on collagen was higher than N3. We tested the effect of HSP70 suppression. Among the six HSP70 inhibitors, VER155008 was efficiently sensitive to S3, and suppression of MRP proteins with HSP70 was observed. Importantly, the treatment of VER155008 reduced LMS along the spinal cord in vivo. In addition, a synergistic effect was observed in the combination treatment of VER155008 with 4-hydroperoxycyclophosphamide. CONCLUSION: Our study suggests that targeting HSP70 can be a promising treatment option to suppress the LMS of MB.

HSP90AB1 Is a Host Factor Required for Transmissible Gastroenteritis Virus Infection.

Transmissible gastroenteritis virus (TGEV) is an important swine enteric coronavirus causing viral diarrhea in pigs of all ages. Currently, the development of antiviral agents targeting host proteins to combat viral infection has received great attention. The heat shock protein 90 (HSP90) is a critical host factor and has important regulatory effects on the infection of various viruses. However, its roles in porcine coronavirus infection remain unclear. In this study, the effect of HSP90 on TGEV infection was evaluated. In addition, the influence of its inhibitor VER-82576 on proinflammatory cytokine (IL-6, IL-12, TNF-α, CXCL10, and CXCL11) production induced by TGEV infection was further analyzed. The results showed that the knockdown of HSP90AB1 and HSP90 inhibitor VER-82576 treatment resulted in a reduction in TGEV M gene mRNA levels, the N protein level, and virus titers in a dose-dependent manner, while the knockdown of HSP90AA1 and KW-2478 treatment had no significant effect on TGEV infection. A time-of-addition assay indicated that the inhibitory effect of VER-82576 on TGEV infection mainly occurred at the early stage of viral replication. Moreover, the TGEV-induced upregulation of proinflammatory cytokine (IL-6, IL-12, TNF-α, CXCL10, and CXCL11) expression was significantly inhibited by VER-82576. In summary, these findings indicated that HSP90AB1 is a host factor enhancing TGEV infection, and the HSP90 inhibitor VER-82576 could reduce TGEV infection and proinflammatory cytokine production, providing a new perspective for TGEV antiviral drug target design.

Inhibition of HSP90 distinctively modulates the global phosphoproteome of Leishmania mexicana developmental stages.

In the unicellular parasites Leishmania spp., the etiological agents of leishmaniasis, a complex infectious disease that affects 98 countries in 5 continents, chemical inhibition of HSP90 protein leads to differentiation from promastigote to amastigote stage. Recent studies indicate potential role for protein phosphorylation in the life cycle control of Leishmania. Also, recent studies suggest a fundamentally important role of RNA-binding proteins (RBPs) in regulating the downstream effects of the HSP90 inhibition in Leishmania. Phosphorylation-dephosphorylation dynamics of RBPs in higher eukaryotes serves as an important on/off switch to regulate RNA processing and decay in response to extracellular signals and cell cycle check points. In the current study, using a combination of highly sensitive TMT labeling-based quantitative proteomic MS and robust phosphoproteome enrichment, we show for the first time that HSP90 inhibition distinctively modulates global protein phosphorylation landscapes in the different life cycle stages of Leishmania, shedding light into a crucial role of the posttranslational modification in the differentiation of the parasite under HSP90 inhibition stress. We measured changes in phosphorylation of many RBPs and signaling proteins including protein kinases upon HSP90 inhibition in the therapeutically relevant amastigote stage. This work provides insights into the importance of HSP90-mediated protein cross-talks and regulation of phosphorylation in Leishmania, thus significantly expanding our knowledge of the posttranslational modification in Leishmania biology.

HSP70 inhibitor amplifies the bFGF‑induced release of IL‑6 in osteoblasts.

Heat shock protein 70 (HSP70) functions as an ATP‑dependent molecular chaperone under stress and is involved in protein homeostasis, folding and degradation. HSP70 inhibitors amplify TGF‑β‑stimulated VEGF synthesis in the mouse osteoblastic MC3T3‑E1 cell line. Basic fibroblast growth factor (bFGF) stimulates IL‑6 release via p38 MAPK in MC3T3‑E1 osteoblast‑like cells. In the present study, the effects of HSP70 on the bFGF‑stimulated release of IL‑6 was evaluated using MC3T3‑E1 osteoblast‑like cells. IL‑6 release and mRNA expression levels were analyzed using ELISA and reverse transcription‑quantitative PCR, respectively. Phosphorylation of p38 MAPK and HSP70 was assessed using western blotting. HSP70 inhibitor VER‑155008 significantly increased the bFGF‑stimulated release of IL‑6 in both MC3T3‑E1 osteoblastic cells and normal human osteoblasts. Furthermore, VER‑155008 significantly enhanced the mRNA expression levels of IL‑6 stimulated by bFGF. Western blotting demonstrated a significant increase in the bFGF‑stimulated phosphorylation of p38 MAPK in VER‑155008‑treated MC3T3‑E1 cells. A significant increase in the bFGF‑stimulated phosphorylation of p38 MAPK was also demonstrated in MC3T3‑E1 cells treated with YM‑08, another HSP70 inhibitor. VER‑155008 or YM‑08 did not significantly affect the expression of HSP70 with or without bFGF stimulation. Finally, the specific p38 MAPK inhibitor SB203580 markedly suppressed the enhancing effects of VER‑155008 on bFGF‑stimulated release of IL‑6. Taken together, these results indicated that HSP70 inhibitor amplified bFGF‑stimulated release of IL‑6 through p38 MAPK activation in the osteoblastic MC3T3‑E1 cell line.

Combination therapy with HSP90 inhibitors and piperlongumine promotes ROS-mediated ER stress in colon cancer cells

Colon cancer is a major cause of cancer-related death. Despite recent improvements in the treatment of colon cancer, new strategies to improve the overall survival of patients are urgently needed. Heat shock protein 90 (HSP90) is widely recognized as a promising target for treating various cancers, including colon cancer. However, no HSP90 inhibitor has been approved for clinical use due to limited efficacy. In this study, we evaluated the antitumor activities of HSP90 inhibitors in combination with piperlongumine in colon cancer cells. We show that combination treatment with HSP90 inhibitors and piperlongumine displayed strong synergistic interaction in colon cancer cells. These agents synergize by promoting ER stress, JNK activation, and DNA damage. This process is fueled by oxidative stress, which is caused by the accumulation of reactive oxygen species. These studies nominated piperlongumine as a promising agent for HSP90 inhibitor-based combination therapy against colon cancer.

A NIR-Activated and Mild-Temperature-Sensitive Nanoplatform with an HSP90 Inhibitor for Combinatory Chemotherapy and Mild Photothermal Therapy in Cancel Cells.

Mild photothermal therapy (PTT) shows great potential to treat cancers while avoiding unwanted damage to surrounding normal cells. However, the efficacy of mild PTT is normally moderate because of the low hyperthermia temperature and limited light penetration depth. Chemotherapy has unlimited penetration but often suffers from unsatisfactory efficacy in view of the occurrence of drug resistance, suboptimal drug delivery and release profile. As a result, the combinatory of chemotherapy and mild PTT would integrate their advantages and overcome the shortcomings. Herein, we synthesized an NIR-activatable and mild-temperature-sensitive nanoplatform (BDPII-gel@TSL) composed of temperature-sensitive liposomes (TSL), heat shock protein 90 (HSP90) inhibitor (geldanamycin) and photothermal agent (BDPII), for dual chemotherapy and mild PTT in cancer cells. BDPII, constructed with donor-acceptor moieties, acts as an excellent near-infrared (NIR) photothermal agent (PTA) with a high photothermal conversion efficiency (80.75%). BDPII-containing TSLs efficiently produce a mild hyperthermia effect (42 °C) under laser irradiation (808 nm, 0.5 W cm-2). Importantly, the phase transformation of TSL leads to burst release of geldanamycin from BDPII-gel@TSL, and this contributes to down-regulation of the overexpression of HSP90, ensuring efficient inhibition of cancer cell growth. This research provides a dual-sensitive synergistic therapeutic strategy for cancer cell treatment.