HSP90 inhibitor NVP-BEP800 affects stability of SRC kinases and growth of T-cell and B-cell acute lymphoblastic leukemias

Valrubicin-loaded immunoliposomes for specific vesicle-mediated cell death in the treatment of hematological cancers

We created valrubicin-loaded immunoliposomes (Val-ILs) using the antitumor prodrug valrubicin, a hydrophobic analog of daunorubicin. Being lipophilic, valrubicin readily incorporated Val-lLs that were loaded with specific antibodies. Val-ILs injected intravenously rapidly reached the bone marrow and spleen, indicating their potential to effectively target cancer cells in these areas. Following the transplantation of human pediatric B-cell acute lymphoblastic leukemia (B-ALL), T-cell acute lymphoblastic leukemia (T-ALL), or acute myeloid leukemia (AML) in immunodeficient NSG mice, we generated patient-derived xenograft (PDX) models, which were treated with Val-ILs loaded with antibodies to target CD19, CD7 or CD33. Only a small amount of valrubicin incorporated into Val-ILs was needed to induce leukemia cell death in vivo, suggesting that this approach could be used to efficiently treat acute leukemia cells. We also demonstrated that Val-ILs could reduce the risk of contamination of CD34+ hematopoietic stem cells by acute leukemia cells during autologous peripheral blood stem cell transplantation, which is a significant advantage for clinical applications. Using EL4 lymphoma cells on immunocompetent C57BL/6 mice, we also highlighted the potential of Val-ILs to target immunosuppressive cell populations in the spleen, which could be valuable in impairing cancer cell expansion, particularly in lymphoma cases. The most efficient Val-ILs were found to be those loaded with CD11b or CD223 antibodies, which, respectively, target the myeloid-derived suppressor cells (MDSC) or the lymphocyte-activation gene 3 (LAG-3 or CD223) on T4 lymphocytes. This study provides a promising preclinical demonstration of the effectiveness and ease of preparation of Val-ILs as a novel nanoparticle technology. In the context of hematological cancers, Val-ILs have the potential to be used as a precise and effective therapy based on targeted vesicle-mediated cell death.

Co-targeting HSP90 alpha and CDK7 overcomes resistance against HSP90 inhibitors in BCR-ABL1+ leukemia cells

HSP90 has emerged as an appealing anti-cancer target. However, HSP90 inhibitors (HSP90i) are characterized by limited clinical utility, primarily due to the resistance acquisition via heat shock response (HSR) induction. Understanding the roles of abundantly expressed cytosolic HSP90 isoforms (α and β) in sustaining malignant cells' growth and the mechanisms of resistance to HSP90i is crucial for exploiting their clinical potential. Utilizing multi-omics approaches, we identified that ablation of the HSP90β isoform induces the overexpression of HSP90α and extracellular-secreted HSP90α (eHSP90α). Notably, we found that the absence of HSP90α causes downregulation of PTPRC (or CD45) expression and restricts in vivo growth of BCR-ABL1+ leukemia cells. Subsequently, chronic long-term exposure to the clinically advanced HSP90i PU-H71 (Zelavespib) led to copy number gain and mutation (p.S164F) of the HSP90AA1 gene, and HSP90α overexpression. In contrast, acquired resistance toward other tested HSP90i (Tanespimycin and Coumermycin A1) was attained by MDR1 efflux pump overexpression. Remarkably, combined CDK7 and HSP90 inhibition display synergistic activity against therapy-resistant BCR-ABL1+ patient leukemia cells via blocking pro-survival HSR and HSP90α overexpression, providing a novel strategy to avoid the emergence of resistance against treatment with HSP90i alone.

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.

High-throughput screening as a drug repurposing strategy for poor outcome subgroups of pediatric B-cell precursor Acute Lymphoblastic Leukemia

Although a great cure rate has been achieved for pediatric BCP-ALL, approximately 15% of patients do not respond to conventional chemotherapy and experience disease relapse. A major effort to improve the cure rates by treatment intensification would result in an undesirable increase in treatment-related toxicity and mortality, raising the need to identify novel therapeutic approaches. High-throughput (HTP) drug screening enables the profiling of patients' responses in vitro and allows the repurposing of compounds currently used for other diseases, which can be immediately available for clinical application. The aim of this study was to apply HTP drug screening to identify potentially effective compounds for the treatment of pediatric BCP-ALL patients with poor prognosis, such as patients with Down Syndrome (DS) or carrying rearrangements involving PAX5 or KMT2A/MLL genes. Patient-derived Xenografts (PDX) samples from 34 BCP-ALL patients (9 DS CRLF2r, 15 PAX5r, 10 MLLr), 7 human BCP-ALL cell lines and 14 hematopoietic healthy donor samples were screened on a semi-automated HTP drug screening platform using a 174 compound library (FDA/EMA-approved or in preclinical studies). We identified 9 compounds active against BCP-ALL (ABT-199/venetoclax, AUY922/luminespib, dexamethasone, EC144, JQ1, NVP-HSP990, paclitaxel, PF-04929113 and vincristine), but sparing normal cells. Ex vivo validations confirmed that the BCL2 inhibitor venetoclax exerts an anti-leukemic effect against all three ALL subgroups at nanomolar concentrations. Overall, this study points out the benefit of HTP screening application for drug repurposing to allow the identification of effective and clinically translatable therapeutic agents for difficult-to-treat childhood BCP-ALL subgroups.

DUSP4 promotes esophageal squamous cell carcinoma progression by dephosphorylating HSP90β

The molecular and pathogenic mechanisms of esophageal squamous cell carcinoma (ESCC) development are still unclear, which hinders the development of effective treatments. In this study, we report that DUSP4 is highly expressed in human ESCC and is negatively correlated with patient prognosis. Knockdown of DUSP4 suppresses cell proliferation and patient-derived xenograft (PDX)-derived organoid (PDXO) growth and inhibits cell-derived xenograft (CDX) development. Mechanistically, DUSP4 directly binds to heat shock protein isoform β (HSP90β) and promotes the ATPase activity of HSP90β by dephosphorylating HSP90β on T214 and Y216. These dephosphorylation sites are critical for the stability of JAK1/2-STAT3 signaling and p-STAT3 (Y705) nucleus translocation. In vivo, Dusp4 knockout in mice significantly inhibits 4-nitrochinoline-oxide-induced esophageal tumorigenesis. Moreover, DUSP4 lentivirus or treatment with HSP90β inhibitor (NVP-BEP800) significantly impedes PDX tumor growth and inactivates the JAK1/2-STAT3 signaling pathway. These data provide insight into the role of the DUSP4-HSP90β-JAK1/2-STAT3 axis in ESCC progression and describe a strategy for ESCC treatment.

Heat-Shock Proteins in Leukemia and Lymphoma: Multitargets for Innovative Therapeutic Approaches

Heat-shock proteins (HSPs) are powerful chaperones that provide support for cellular functions under stress conditions but also for the homeostasis of basic cellular machinery. All cancer cells strongly rely on HSPs, as they must continuously adapt to internal but also microenvironmental stresses to survive. In solid tumors, HSPs have been described as helping to correct the folding of misfolded proteins, sustain oncogenic pathways, and prevent apoptosis. Leukemias and lymphomas also overexpress HSPs, which are frequently associated with resistance to therapy. HSPs have therefore been proposed as new therapeutic targets. Given the specific biology of hematological malignancies, it is essential to revise their role in this field, providing a more adaptable and comprehensive picture that would help design future clinical trials. To that end, this review will describe the different pathways and functions regulated by HSP27, HSP70, HSP90, and, not least, HSP110 in leukemias and lymphomas.

Endothelial cell-leukemia interactions remodel drug responses, uncovering T-ALL vulnerabilities

T-cell acute lymphoblastic leukemia (T-ALL) is an aggressive and often incurable disease. To uncover therapeutic vulnerabilities, we first developed T-ALL patient-derived tumor xenografts (PDXs) and exposed PDX cells to a library of 433 clinical-stage compounds in vitro. We identified 39 broadly active drugs with antileukemia activity. Because endothelial cells (ECs) can alter drug responses in T-ALL, we developed an EC/T-ALL coculture system. We found that ECs provide protumorigenic signals and mitigate drug responses in T-ALL PDXs. Whereas ECs broadly rescued several compounds in most models, for some drugs the rescue was restricted to individual PDXs, suggesting unique crosstalk interactions and/or intrinsic tumor features. Mechanistically, cocultured T-ALL cells and ECs underwent bidirectional transcriptomic changes at the single-cell level, highlighting distinct "education signatures." These changes were linked to bidirectional regulation of multiple pathways in T-ALL cells as well as in ECs. Remarkably, in vitro EC-educated T-ALL cells transcriptionally mirrored ex vivo splenic T-ALL at single-cell resolution. Last, 5 effective drugs from the 2 drug screenings were tested in vivo and shown to effectively delay tumor growth and dissemination thus prolonging overall survival. In sum, we developed a T-ALL/EC platform that elucidated leukemia-microenvironment interactions and identified effective compounds and therapeutic vulnerabilities.

A Boolean-based machine learning framework identifies predictive biomarkers of HSP90-targeted therapy response in prostate cancer

Precision medicine has emerged as an important paradigm in oncology, driven by the significant heterogeneity of individual patients' tumour. A key prerequisite for effective implementation of precision oncology is the development of companion biomarkers that can predict response to anti-cancer therapies and guide patient selection for clinical trials and/or treatment. However, reliable predictive biomarkers are currently lacking for many anti-cancer therapies, hampering their clinical application. Here, we developed a novel machine learning-based framework to derive predictive multi-gene biomarker panels and associated expression signatures that accurately predict cancer drug sensitivity. We demonstrated the power of the approach by applying it to identify response biomarker panels for an Hsp90-based therapy in prostate cancer, using proteomic data profiled from prostate cancer patient-derived explants. Our approach employs a rational feature section strategy to maximise model performance, and innovatively utilizes Boolean algebra methods to derive specific expression signatures of the marker proteins. Given suitable data for model training, the approach is also applicable to other cancer drug agents in different tumour settings.

Heterocyclic Compounds as Hsp90 Inhibitors: A Perspective on Anticancer Applications

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.

Rutin Suppresses DMBA Carcinogenesis in the Breast Through Modulating IL-6/NF-κB, SRC1/HSP90 and ER-α

Rutin dietary supplements may offer pharmacological benefits as anticancer and antiinflammatory properties. This study aimed to investigate the inhibitory and protective effect of rutin on signaling pathways of mammary gland carcinogenesis expermintally induced in female rats by 7,12-di-methyl benz (a) anthracene (DMBA). Results showed that rutin administration ameliorated DMBA toxicity and carcinogic effect on kidney and liver revealed by a significant decrease of urea and creatinine levels, and the activity of the liver enzymes alanine aminotransferase (ALT) and alkaline phosphatase (ALP). The antioxidant state indicated by the total antioxidant capacity (TAC) was significantly increased accompanied by a reduction in the inflammatory markers of interleukin-1β (IL-1B), interleukin-6 (IL-6), and tumor necrosis factor (TNF-α) with induction of apoptosis indicated by a significant increase in caspase-3 level. Rutin significantly reduced the levels of the tumor markers carcinoma antigen 15-3 (CA 15-3) and proto-oncogene tyrosine-protein kinase Src1 (Src1). along with downregulation of nuclear factor-kB (NF-κB), heat shock protein 90 (HSP 90), and inducible nitric oxide synthase (iNOS) gene expression. The present study demonstrated the beneficial anticancer activity of rutin as a protective and therapeutic agent. Rutin induces its antitumor activity through elevation of the antioxidant state, inhibition of inflammatory cytokines, downregulation of oncogenes expression, and stimulation of apoptosis.

ACY-1215 suppresses the proliferation and induces apoptosis of chronic myeloid leukemia cells via the ROS/PTEN/Akt pathway

Chronic myeloid leukemia (CML) is a hematological tumor marked by the bcr-abl fusion gene formed by t (9;22) (q34; q11), which translated into the BCR-ABL protein. Tyrosine kinase inhibitors (TKIs) have been widely used to cure CML patients. Nevertheless, the emergence of TKI resistance has become the problem to the outcome of CML patients. Histone deacetylase 6 (HDAC6), a kind of Hsp90α deacetylase, was detected to be overexpressed in chronic myeloid leukemia stem cells. Besides, the loss of HDAC6 enzymatic activity can result in the degradation of Hsp90α's client proteins, such as BCR-ABL, the oncoprotein of CML. Here, we explored the expression of HDAC6 and discovered that it was upregulated compared with control in CML. Then we explored the effect of Rocilinostat (ACY-1215), a specific HDAC6 inhibitor, on CML cells. Our results proved that ACY-1215 could induce apoptosis and cell cycle arrest in a ROS-dependent manner. Moreover, we detected a downregulation of the BCR-ABL signaling pathway in the ACY-1215 treatment group. Mechanistically, we noted that the upregulation of PTEN was induced after being treated by ACY-1215 and its downstream protein p-Akt was decreased. The Akt activator SC79 can partially reverse the influence of ACY-1215 on CML cells. Besides, our results also proved that ACY-1215 can synergize with imatinib to suppress chronic myeloid leukemia in vitro and in vivo. On the whole, our study revealed that HDAC6 is a possible therapeutic target in CML, and the combination therapy of TKI and HDAC6 inhibitor may improve the outcome of CML patients.

Heat shock protein 90 is a new potential target of anti-rejection therapy in allotransplantation

The critical roles of heat shock protein 90 (HSP90) in immune reactions associated with viral infection and autoimmune disease are well known. To date, however, its roles in the alloimmune response and the immunosuppressive effect of HSP90 inhibitors in allotransplantation have remained unknown. The purpose of this study was to examine the therapeutic efficacy of the HSP90 inhibitor 17-DMAG in allotransplantation models. C57BL/6 (H-2b) and BALB/c (H-2d) mice were used as donors for and recipients of skin and heart transplantation, respectively. Treatment with 17-DMAG (daily i.p.) or a vehicle was initiated 3 days before transplantation. Immunological outcomes were assessed by histopathological examinations, flow cytometric analysis, quantitative RT-PCR, ELISA, ELISPOT assay, and MLR. 17-DMAG treatment significantly prolonged the survival of both skin and heart allografts. In 17-DMAG-treated mice, donor-reactive splenocytes producing IFN-γ were significantly reduced along with the intragraft mRNA expression level and serum concentration of IFN-γ. Intragraft mRNA expression of cytokines and chemokines associated with both innate and adaptive immunity was suppressed in 17-DMAG-treated group. MLR showed suppression of the donor-specific proliferation of CD4 + T and CD19 + B cells in the spleens of 17-DMAG-treated mice. 17-DMAG treatment also reduced the number of activated NK cells. Furthermore, the treatment lowered the titers of donor-specific antibodies in the serum and prolonged a second skin allograft in mice sensitized by previous skin transplantation. HSP90 inhibition by 17-DMAG can affect various immune responses, including innate immunity, adaptive immunity, and humoral immunity, suggesting its therapeutic potential against acute rejection in allotransplantation.

Acute lymphoblastic leukemia-derived extracellular vesicles affect quiescence of hematopoietic stem and progenitor cells

Patient-derived xenografted (PDX) models were generated through the transplantation of primary acute lymphoblastic leukemia (ALL) cells into immunodeficient NSG mice. We observed that ALL cells from mouse bone marrow (BM) produced extracellular vesicles (EVs) with specific expression of inducible heat shock protein HSP70, which is commonly activated in cancer cells. Taking advantage of this specific expression, we designed a strategy to generate fluorescent HSP70-labeled ALL EVs and monitor the impact of these EVs on endogenous murine BM cells ex vivo and in vivo. We discovered that hematopoietic stem and progenitor cells (HSPC) were mainly targeted by ALL EVs, affecting their quiescence and maintenance in the murine BM environment. Investigations revealed that ALL EVs were enriched in cholesterol and other metabolites that contribute to promote the mitochondrial function in targeted HSPC. Furthermore, using CD34⁺ cells isolated from cord blood, we confirmed that ALL EVs can modify quiescence of human HSPC. In conclusion, we have discovered a new oncogenic mechanism illustrating how EVs produced by proliferative ALL cells can target and compromise a healthy hematopoiesis system during leukemia development.

HSP90 inhibitors 17-AAG and VER-82576 inhibit porcine deltacoronavirus replication in vitro

Porcine deltacoronavirus (PDCoV) is highly pathogenic to piglets, and no specific drugs or vaccines are available for the prevention and treatment of PDCoV infection, the need for antiviral therapies is pressing. HSP90 inhibitors have potent inhibitory effects against the replication of numerous viruses, hence we evaluated three HSP90 inhibitors, 17-AAG, VER-82576, and KW-2478, for their effects on PDCoV infection in vitro. We evaluated their effectivenesses at suppressing PDCoV by qRT-PCR, western blot, and TCID₅₀ assay, and found that 17-AAG and VER-82576 inhibited PDCoV at the early stage of replication, while KW-2478 showed no significant antiviral activity at any stage of infection. These results indicated that the PDCoV-inhibitory effects of 17-AAG and VER-82576 might be exerted by targeting host cell factor HSP90AB1 but not HSP90AA1. Further study showed that HSP90AB1 mRNA and protein levels were not significantly different in 17-AAG and VER-82576-treated cells versus control cells. 17-AAG and VER-82576 were also evaluated for their effects on the expressions of TNF-α, IL-6, and IL-12, which are PDCoV-induced proinflammatory cytokines. We found that both 17-AAG and VER-82576 inhibited the expressions of TNF-α, IL-6, and IL-12 to varying degrees, but in a dose dependent manner. From our data we can conclude that the HSP90 inhibitors 17-AAG and VER-82576 are promising candidates for the treatment of PDCoV infection.