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

AFP-HSP90 mediated MYC/MET activation promotes tumor progression in hepatocellular carcinoma and gastric cancers

Alpha-fetoprotein (AFP) elevation is a well-known biomarker in various diseases, particularly in the diagnosis of hepatocellular carcinoma (HCC). Intracellular AFP has been previously implicated in promoting tumorigenesis. In this study, we discovered that AFP enhances the stability of oncoproteins c-MYC and c-MET, thereby facilitating the progression of liver and gastric tumors. Our findings suggest that AFP acts by stabilizing these oncoproteins, which are clients of heat shock protein 90 (HSP90), and prevents their degradation through ubiquitination. Intriguingly, we identified AFP as a novel co-chaperone of HSP90, demonstrating its ability to regulate the stabilization of HSP90 client proteins. Furthermore, our results indicate that inhibiting AFP or HSP90 enhances the cytotoxicity of chemotherapeutic agents in AFP-producing HCC and gastric cancer cells. These findings have significant implications for the development of therapeutic strategies targeting AFP-producing tumors, as the AFP-HSP90-mediated activation of c-MYC and c-MET provides new insights into potential treatment approaches. In summary, this study sheds light on the role of AFP in promoting tumor progression by stabilizing oncoproteins through its interaction with HSP90. The identification of this mechanism opens up new avenues for therapeutic interventions in AFP-producing tumors.

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

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

Novel cancer treatment paradigm targeting hypoxia-induced factor in conjunction with current therapies to overcome resistance

Chemotherapy, radiotherapy, targeted therapy, and immunotherapy are established cancer treatment modalities that are widely used due to their demonstrated efficacy against tumors and favorable safety profiles or tolerability. Nevertheless, treatment resistance continues to be one of the most pressing unsolved conundrums in cancer treatment. Hypoxia-inducible factors (HIFs) are a family of transcription factors that regulate cellular responses to hypoxia by activating genes involved in various adaptations, including erythropoiesis, glucose metabolism, angiogenesis, cell proliferation, and apoptosis. Despite this critical function, overexpression of HIFs has been observed in numerous cancers, leading to resistance to therapy and disease progression. In recent years, much effort has been poured into developing innovative cancer treatments that target the HIF pathway. Combining HIF inhibitors with current cancer therapies to increase anti-tumor activity and diminish treatment resistance is one strategy for combating therapeutic resistance. This review focuses on how HIF inhibitors could be applied in conjunction with current cancer treatments, including those now being evaluated in clinical trials, to usher in a new era of cancer therapy.

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

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

LSD1 interacting with HSP90 promotes skin wound healing by inducing metabolic reprogramming of hair follicle stem cells through the c-MYC/LDHA axis

It has been demonstrated that hair follicle stem cells (HFSCs) can contribute to wound closure and repair. However, the specific mechanism remains unclear due to the complexity of the wound repair process. Lysine-specific demethylase 1 (LSD1), an important gene for the regulation of stem cell differentiation, has been reported to participate in wound healing regulation. Heat shock protein 90 (HSP90), a chaperone protein, is recently discovered to be a driver gene for wound healing. This study explored the molecular mechanisms by which the binding between LSD1 and HSP90 affects the role of HFSCs during skin wound healing. Following bioinformatics analysis, the key genes acting on HFSCs were identified. The expression of LSD1, HSP90, and c-MYC was found to be upregulated in differentiated HFSCs. Analysis of their binding affinity revealed that LSD1 interacted with HSP90 to enhance the stability of the transcription factor c-MYC. Lactate dehydrogenase A (LDHA) has been documented to be essential for HFSC activation. Therefore, we speculate that LDHA may induce the differentiation of HFSCs through glucose metabolism reprogramming. The results showed that c-MYC activated LDHA activity to promote glycolytic metabolism, proliferation, and differentiation of HFSCs. Finally, in vivo animal experiments further confirmed that LSD1 induced skin wound healing in mice via the HSP90/c-MYC/LDHA axis. From our data, we conclude that LSD1 interacting with HSP90 accelerates skin wound healing by inducing HFSC glycolytic metabolism, proliferation, and differentiation via c-MYC/LDHA axis.

Exploration of anti-leukemic effect of soft coral-derived 13-acetoxysarcocrassolide: Induction of apoptosis via oxidative stress as a potent inhibitor of heat shock protein 90 and topoisomerase II

13-Acetoxysarcocrassolide (13-AC) is a marine cembranoid derived from the aquaculture soft coral of Lobophytum crassum. The cytotoxic effect of 13-AC against leukemia cells was previously reported but its mechanism of action is still unexplored. In the current study, we showed that 13-AC induced apoptosis of human acute lymphoblastic leukemia Molt4 cells, as evidenced by the cleavage of PARP and caspases, phosphatidylserine externalization, as well as the disruption of mitochondrial membrane potential. The use of N-acetylcysteine (NAC), a reactive oxygen species (ROS) scavenger, attenuated the cytotoxic effect induced by 13-AC. Molecular docking and thermal shift assay indicated that the cytotoxic mechanism of action of 13-AC involved the inhibition of heat shock protein 90 (Hsp 90) activity by eliciting the level of Hsp 70 and topoisomerase IIα in Molt4 cells. 13-AC also exhibited potent antitumor activity by reducing the tumor volume (48.3%) and weight (72.5%) in the in vivo Molt4 xenograft mice model. Our findings suggested that the marine cembranoid, 13-AC, acted as a dual inhibitor of Hsp 90 and topoisomerase IIα, exerting more potent apoptotic activity via the enhancement of ROS generation.

Autophagy, molecular chaperones, and unfolded protein response as promoters of tumor recurrence

Tumor recurrence is a paradoxical function of a machinery, whereby a small proportion of the cancer cell population enters a resistant, dormant state, persists long-term in this condition, and then transitions to proliferation. The dormant phenotype is typical of cancer stem cells, tumor-initiating cells, disseminated tumor cells, and drug-tolerant persisters, which all demonstrate similar or even equivalent properties. Cancer cell dormancy and its conversion to repopulation are regulated by several protein signaling systems that inhibit or induce cell proliferation and provide optimal interrelations between cancer cells and their special niche; these systems act in close connection with tumor microenvironment and immune response mechanisms. During dormancy and reawakening periods, cell proteostasis machineries, autophagy, molecular chaperones, and the unfolded protein response are recruited to protect refractory tumor cells from a wide variety of stressors and therapeutic insults. Proteostasis mechanisms functionally or even physically interfere with the main regulators of tumor relapse, and the significance of these interactions and implications in the tumor recurrence phases are discussed in this review.

The Chaperone System in Salivary Glands: Hsp90 Prospects for Differential Diagnosis and Treatment of Malignant Tumors

Salivary gland tumors represent a serious medical problem and new tools for differential diagnosis and patient monitoring are needed. Here, we present data and discuss the potential of molecular chaperones as biomarkers and therapeutic targets, focusing on Hsp10 and Hsp90. The salivary glands are key physiological elements but, unfortunately, the information and the means available for the management of their pathologies, including cancer, are scarce. Progress in the study of carcinogenesis has occurred on various fronts lately, one of which has been the identification of the chaperone system (CS) as a physiological system with presence in all cells and tissues (including the salivary glands) that plays a role in tumor-cell biology. The chief components of the CS are the molecular chaperones, some of which belong to families of evolutionarily related molecules named heat shock protein (Hsp). We are quantifying and mapping these molecular chaperones in salivary glands to determine their possible role in the carcinogenetic mechanisms in these glands and to assess their potential as diagnostic biomarkers and therapeutic targets. Here, we report recent findings on Hsp10 and Hsp90 and show that the quantitative and topographic patterns of tissue Hsp90 are distinctive of malignant tumors and differentiate benign from malignant lesions. The Hsp90 results show a correlation between quantity of chaperone and tumor progression, which in turn calls for negative chaperonotherapy, namely, elimination/inhibition of the chaperone to stop the tumor. We found that in vitro, the Hsp90 inhibitor Ganetespib is cytotoxic for the salivary gland UM-HACC-2A cell line. The drug, by interfering with the pro-survival NF-κB pathway, hampers cellular proliferation and migration, and favors apoptosis, and can, therefore, be considered a suitable candidate for future experimentation to develop a treatment for salivary gland tumors.

Harnessing the Heterogeneity of Prostate Cancer for Target Discovery Using Patient-Derived Explants

Simple Summary

There is a widespread push toward more biologically relevant pre-clinical models of prostate cancer that can improve the discovery and translation of new drugs and biomarkers for this disease. Patient-derived explant culture is an innovative pre-clinical model that utilizes surgical prostate cancer specimens in a way that retains the architecture, microenvironment and heterogeneity of prostate tumors—factors that critically influence cell behavior and response to therapy. With increasing tissue complexity comes increasing complexity of analysis. The aim of this study was to provide critical information for the successful application and analysis of the patient-derived prostate cancer explant model.

Abstract

Prostate cancer is a complex and heterogeneous disease, but a small number of cell lines have dominated basic prostate cancer research, representing a major obstacle in the field of drug and biomarker discovery. A growing lack of confidence in cell lines has seen a shift toward more sophisticated pre-clinical cancer models that incorporate patient-derived tumors as xenografts or explants, to more accurately reflect clinical disease. Not only do these models retain critical features of the original tumor, and account for the molecular diversity and cellular heterogeneity of prostate cancer, but they provide a unique opportunity to conduct research in matched tumor samples. The challenge that accompanies these complex tissue models is increased complexity of analysis. With over 10 years of experience working with patient-derived explants (PDEs) of prostate cancer, this study provides guidance on the PDE method, its limitations, and considerations for addressing the heterogeneity of prostate cancer PDEs that are based on statistical modeling. Using inhibitors of the molecular chaperone heat shock protein 90 (Hsp90) as an example of a drug that induces robust proliferative response, we demonstrate how multi-omics analysis in prostate cancer PDEs is both feasible and essential for identification of key biological pathways, with significant potential for novel drug target and biomarker discovery.

Improving therapeutic resistance: beginning with targeting the tumor microenvironment

Cancer is a serious threat to human health and life. The tumor microenvironment (TME) not only plays a key role in the occurrence, development and metastasis of cancer, but also has a profound impact on treatment resistance. To improve and solve this problem, an increasing number of strategies targeting the TME have been proposed, and great progress has been made in recent years. This article reviews the characteristics and functions of the main matrix components of the TME and the mechanisms by which each component affects drug resistance. Furthermore, this article elaborates on targeting the TME as a strategy to treat acquired drug resistance, reduce tumor metastasis, recurrence, and improve efficacy.

CircVCAN/SUB1 up-regulates MYC/HSP90β to enhance the proliferation and migration of glioma cells

BACKGROUND

Gliomas are the most malignant and aggressive form of brain tumors, and account for the majority of brain cancer related deaths. Previous studies have reported that SUB1 serves as a novel RBP, which is highly expressed in tumors.

AIM

In our research, we aimed at exploring the regulatory mechanism of SUB1 in glioma cells.

METHODS

RT-qPCR was conducted to measure the expression of SUB1, HSP90β and MYC in glioma cells in U87 cell. Cell function tests were conducted to identify how the ectopic SUB1 expression influenced the proliferation and migration of glioma cells. Also, functional assays and mechanism experiments were carried out to figure out the relationship among circVCAN, SUB1 and MYC/HSP90β.

RESULTS

SUB1 expression was up-regulated in glioma cells. The inhibition of SUB1 expression suppressed the proliferation and migration of glioma cells, while the up-regulation of that accelerated the proliferation and migration of glioma cells. CircVCAN could up-regulate the expression of MYC/HSP90β by recruiting SUB1, thereby promoting glioma progression.

CONCLUSION

SUB1 plays a significant role in the survival and migration of glioma cells.

HSP90 inhibition downregulates DNA replication and repair genes via E2F1 repression

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

Patient-derived xenograft: a developing tool for screening biomarkers and potential therapeutic targets for human esophageal cancers

Esophageal cancer (EC) represents a human malignancy, diagnosed often at the advanced stage of cancer and resulting in high morbidity and mortality. The development of precision medicine allows for the identification of more personalized therapeutic strategies to improve cancer treatment. By implanting primary cancer tissues into immunodeficient mice for expansion, patient-derived xenograft (PDX) models largely maintain similar histological and genetic representations naturally found in patients' tumor cells. PDX models of EC (EC-PDX) provide fine platforms to investigate the tumor microenvironment, tumor genomic heterogeneity, and tumor response to chemoradiotherapy, which are necessary for new drug discovery to combat EC in addition to optimization of current therapeutic strategies for EC. In this review, we summarize the methods used for establishing EC-PDX models and investigate the utilities of EC-PDX in screening predictive biomarkers and potential therapeutic targets. The challenge of this promising research tool is also discussed.

The anti-angiogenesis role of FBXW7 in diabetic retinopathy by facilitating the ubiquitination degradation of c-Myc to orchestrate the HDAC2

Diabetic retinopathy (DR) is the most prevalently occurring microvascular complication in diabetic patients that triggers severe visual impairments. The anti-angiogenesis role of FBXW7 has been identified in breast cancer. Therefore, this study intends to decipher the mechanism of FBXW7 in angiogenesis of DR. DR model was induced on mice using high-glucose (HG) and high-fat diet, and retinal microvascular endothelial cells (RMECs) isolated from normal mice were induced with HG, followed by evaluation of FBXW7, Ki67, HIF-1α and VEGF expression by immunofluorescence, immunohistochemistry or Western blot analysis. After gain- and loss-of-function assays in normal and DR mice, angiogenesis was assessed by CD31 fluorescence staining and Western blot analysis. After ectopic expression and silencing experiments in HG-induced RMECs, RMEC proliferation, migration and angiogenesis were, respectively, determined by EdU, Transwell and in vitro angiogenesis assays. The impact of FBXW7 on the ubiquitination of c-Myc was studied by cycloheximide chase assay and proteasome inhibition, and the binding of c-Myc to HDAC2 promoter by dual-luciferase reporter gene experiment. DR mice and HG-induced RMECs possessed down-regulated FBXW7 and up-regulated Ki67, HIF-1α and VEGF. Silencing FBXW7 enhanced angiogenesis in normal mouse retinal tissue, but overexpressing FBXW7 or silencing c-Myc diminished angiogenesis in DR mouse retinal tissue. Overexpressing FBXW7 or silencing c-Myc depressed proliferation, migration and angiogenesis in HG-induced RMECs. FBXW7 induced c-Myc ubiquitination degradation, and c-Myc augmented HDAC2 expression by binding to HDAC2 promoter. Conclusively, our data provided a novel sight of anti-angiogenesis role of FBXW7 in DR by modulating the c-Myc/HDAC2 axis.