Breast cancer is the most commonly diagnosed cancer among women and the second leading cause of cancer deaths in women. A majority of these breast cancer deaths are due to metastasis, which occurs when primary tumor cells invade into the blood stream to travel and colonize at distant organ sites. Metastatic colonization is the rate-limiting step of metastasis. Heat shock factor 1 (HSF1) is a transcription factor that has been shown to be involved in promoting malignancy with a function in metastatic dissemination due to its contribution to promoting epithelial-to-mesenchymal transition. The role of HSF1 in colonization is unclear. In this study, we observed that HSF1 was essential for metastatic colonization. Consistent with these findings, we also observed that HSF1 was more active in human metastatic tumors compared to primary tumors. HSF1 was also seen to be activated during in vitro colony formation, which was accompanied by increases in amyloid beta (Aβ) fibrils, which was also observed in human metastatic tumors. Aβ fibrils led to HSF1 activation and depletion or inhibition of HSF1 led to increases in Aβ fibrils. HSF1 inhibition with small molecule inhibitors suppressed in vitro colony formation and mammosphere growth of metastatic breast cancer cells. These results suggest that colonization increases Aβ fibril formation that subsequently activates HSF1 as a cell survival mechanism that is essential for metastatic initiation and outgrowth.

Heat shock factor 1 (HSF1) is the master orchestrator of the heat shock response (HSR), a critical process for maintaining cellular health and protein homeostasis. These effects are achieved through rapid expression of molecular chaperones, the heat shock proteins (HSPs), which ensure correct protein folding, repair, degradation and stabilization of multiprotein complexes. In addition to its role in the HSR, HSF1 influences the cell cycle, including processes such as S phase progression and regulation of the p53 pathway, highlighting its importance in cellular protein synthesis and division. While HSF1 activity offers neuroprotective benefits in neurodegenerative diseases, its proteome-stabilizing function may also reinforce tumorigenic transformation. HSF1 overexpression in many types of cancer reportedly enhances cell growth enables survival, alters metabolism, weakens immune response and promotes angiogenesis or epithelial-mesenchymal transition (EMT) as these cells enter a form of "HSF1 addiction". Furthermore, the client proteins of HSF1-regulated chaperones, particularly Hsp90, include numerous key players in classical tumorigenic pathways. HSF1 thus presents a promising therapeutic target for cancer treatment, potentially in combination with HSP inhibitors to alleviate typical initiation of HSR upon their use.

The stress-associated chaperone system is an actionable target in cancer therapies. It is ubiquitously upregulated in cancer tissues and enables tumorigenicity by stabilizing oncoproteins. Most inhibitors target the key component, heat-shock protein 90 (HSP90). Although HSP90 inhibitors are highly tumor-selective, they fail in clinical trials. These failures are partly due to interference with a negative regulatory feedback loop in the heat-shock response (HSR): in response to HSP90 inhibition, there is compensatory synthesis of stress-inducible chaperones, mediated by the transcription factor heat-shock-factor 1 (HSF1). We recently identified that wild-type p53 reduces the HSR by repressing HSF1 via a p21-CDK4/6-MAPK-HSF1 axis. Here, we test whether in HSP90-based therapies, simultaneous p53 activation or direct cell cycle inhibition interrupts the deleterious HSF1-HSR axis and improves the efficiency of HSP90 inhibitors. We found that the clinically relevant p53 activator Idasanutlin suppresses the HSF1-HSR activity in HSP90 inhibitor-based therapies. This combination synergistically reduces cell viability and accelerates cell death in p53-proficient colorectal cancer (CRC) cells, murine tumor-derived organoids, and patient-derived organoids (PDOs). Mechanistically, upon combination therapy, CRC cells upregulate p53-associated pathways, apoptosis, and inflammatory pathways. Likewise, in a CRC mouse model, dual HSF1-HSP90 inhibition represses tumor growth and remodels immune cell composition. Importantly, inhibition of the cyclin-dependent kinases 4/6 (CDK4/6) under HSP90 inhibition phenocopies synergistic repression of the HSR in p53-proficient CRC cells. Moreover, in p53-deficient CRC cells, HSP90 inhibition in combination with CDK4/6 inhibitors similarly suppresses the HSF1-HSR and reduces cancer growth. Likewise, p53-mutated PDOs respond to dual HSF1-HSP90 inhibition, providing a strategy to target CRC independent of the p53 status. In sum, we provide new options to improve HSP90-based therapies to enhance CRC therapies.

BackgroundHeat shock factor 1 (HSF1), the principal transcriptional regulator of cellular stress responses, has been exhibited to play a role in the progression of various human cancer types. However, the function of HSF1 in endometrial cancer (EC) has not yet been evaluated.ObjectiveThis study examined the expression and role of HSF1 in EC.MethodsImmunohistochemistry was performed to explore HSF1 level in 135 endometrial tissue specimens. The relationship between HSF1 level and EC patients' clinicopathological characteristics was analyzed. Quantitative reverse-transcriptase polymerase chain reaction (qRT-PCR) and Western blotting were employed to explore HSF1 expression level in tissues in vitro. Small interfering RNA (siRNA) was employed to suppress HSF1 expression level. The invasion and migration capacities were evaluated using transwell and wound healing assays. Cell cycle arrest and apoptosis were assessed by flow cytometric analysis.ResultsEC tissues exhibited higher HSF1 expression level compared with normal endometrial and atypical endometrial hyperplasia tissues. High HSF1 expression level was associated with histological grade, muscular invasion, lymph node metastasis, and estrogen receptor (ER) expression level in EC tissues and cells. Kaplan-Meier analysis indicated that EC patients with elevated HSF1 expression level had poorer overall survival. Knockdown of HSF1 in EC cells resulted in cell cycle arrest, increased apoptosis, and inhibited EC cell proliferation, invasion, and migration.ConclusionThe results demonstrated that HSF1 could function as an oncogene in EC. HSF1 could play a notable role in EC progression. HSF1 may be a potential molecular target for both the treatment and prognosis of patients with EC.

Heat Shock Factor 1 (HSF1) is a major transcriptional factor regulating the heat shock response and has become a potential target for overcoming cancer chemoresistance. This review comprehensively examines HSF1's role in chemoresistance and its potential as a therapeutic target in cancer. We explore the complex, intricate mechanism that regulates the activation of HSF1, HSF1's function in promoting resistance to chemotherapy, and the strategies used to manipulate HSF1 for therapeutic benefit. In addition, we discuss emerging research implicating HSF1's roles in autophagy, apoptosis, DNA damage repair, drug efflux, and thus chemoresistance. This article highlights the significance of HSF1 in cancer chemoresistance and its potential as a target for enhancing cancer treatment efficacy.

Cells maintain homeostasis via dynamic regulation of stress response pathways. Stress pathways transiently induce response regulons via negative feedback loops, but the extent to which individual genes provide feedback has not been comprehensively measured for any pathway. Here, we disrupted the induction of each gene in the Saccharomyces cerevisiae heat shock response (HSR) and quantified cell growth and HSR dynamics following heat shock. The screen revealed a core feedback loop governing the expression of the chaperone Hsp70 reinforced by an auxiliary feedback loop controlling Hsp70 subcellular localization. Mathematical modeling and live imaging demonstrated that multiple HSR targets converge to promote Hsp70 nuclear localization via its release from cytosolic condensates. Following ethanol stress, a distinct set of factors similarly converged on Hsp70, suggesting that nonredundant subsets of the HSR regulon confer feedback under different conditions. Flexible spatiotemporal feedback loops may broadly organize stress response regulons and expand their adaptive capacity.

The heat shock factor (HSF) family of transcription factors drives gene expression programs that maintain cytosolic protein homeostasis (proteostasis) in response to a vast array of physiological and exogenous stressors. The importance of HSF function has been demonstrated in numerous physiological and pathological contexts. Evidence accumulating over the last two decades has revealed that the regulatory programs driven by the HSF family can vary dramatically depending on the context in which it is activated. To broadly maintain proteostasis across these contexts, HSFs must bind and appropriately regulate the correct target genes at the correct time. Here, we discuss "the heat shock factor code"-our current understanding of how human cells use HSF paralog diversification and interplay, local concentration, post-translational modifications, and interactions with other proteins to enable the functional plasticity required for cellular resilience across a multitude of environments.

Protein mutational landscapes are sculpted by the impacts of the resulting amino acid substitutions on the protein's stability and folding or aggregation kinetics. These properties can, in turn, be modulated by the composition and activities of the cellular proteostasis network. Heat shock factor 1 (HSF1) is the master regulator of the cytosolic and nuclear proteostasis networks, dynamically tuning the expression of cytosolic and nuclear chaperones and quality control factors to meet demand. Chronic increases in HSF1 levels and activity are prominent hallmarks of cancer cells. One plausible explanation for this observation is that the consequent upregulation of proteostasis factors could biophysically facilitate the acquisition of oncogenic mutations. Here, we experimentally evaluate the impacts of chronic HSF1 activation on the mutational landscape accessible to the quintessential oncoprotein p53. Specifically, we apply quantitative deep mutational scanning of p53 to assess how HSF1 activation shapes the mutational pathways by which p53 can escape cytotoxic pressure conferred by the small molecule nutlin-3, which is a potent antagonist of the p53 negative regulator MDM2. We find that activation of HSF1 broadly increases the fitness of dominant-negative substitutions within p53. This effect of HSF1 activation was particularly notable for non-conservative, biophysically unfavorable amino acid substitutions within buried regions of the p53 DNA-binding domain. These results indicate that chronic HSF1 activation profoundly shapes the oncogenic mutational landscape, preferentially supporting the acquisition of cancer-associated substitutions that are biophysically destabilizing. Along with providing the first experimental and quantitative insights into how HSF1 influences oncoprotein mutational spectra, these findings also implicate HSF1 inhibition as a strategy to reduce the accessibility of mutations that drive chemotherapeutic resistance and metastasis.

To maintain microenvironmental and cellular homeostasis, cells respond to multiple stresses by activating characteristic cellular mechanisms consisting of receptors, signal transducers, and effectors. Dysfunction of these mechanisms can trigger multiple human diseases as well as cancers. Dual-specificity tyrosine-regulated kinases (DYRKs) are members of the CMGC group and are evolutionarily conserved from yeast to mammals. Previous studies revealed that DYRK2 has important roles in the regulation of the cell cycle and survival in cancer cells. On the other hand, recent studies show that DYRK2 also exhibits significant functions in multiple cellular stress responses and in maintaining cellular homeostasis. Hence, the further elucidation of mechanisms underlying DYRK2's diverse responses to various stresses helps to promote the advancement of innovative clinical therapies and pharmacological drugs. This review summarizes the molecular mechanisms of DYRK2, particularly focusing on cellular stress responses.

Heat shock factor 1 (HSF1) responds to stress to mount the heat shock response (HSR), a conserved transcriptional program that allows cells to maintain proteostasis by upregulating heat shock proteins (HSPs). The homeostatic stress regulation of HSF1 plays a key role in human physiology and health but its mechanism has remained difficult to pinpoint. Recent work in the budding yeast model has implicated stress-inducible chaperones of the HSP70 family as direct negative regulators of HSF1 activity. Here, we have investigated the latency control and activation of human HSF1 by HSP70 and misfolded proteins. Purified oligomeric HSF1-HSP70 (HSPA1A) complexes exhibited basal DNA binding activity that was inhibited by increasing the levels of HSP70 and, importantly, misfolded proteins reverted the inhibitory effect. Using site-specific UV photo-crosslinking, we monitored HSP70-HSF1 complexes in HEK293T cells. While HSF1 was bound by the substrate binding domain of HSP70 in unstressed cells, activation of HSF1 by heat shock as well as by inducing the misfolding of newly synthesized proteins resulted in release of HSF1 from the chaperone. Taken our results together, we conclude that latent HSF1 populate dynamic complexes with HSP70, which are sensitive to increased levels of misfolded proteins that compete for binding to the HSP70 substrate binding domain. Thus, human HSF1 is activated by various stress conditions that all titrate available HSP70.

The highest frequency of genetic alterations in the tumor suppressor ARID1A occurs in malignancies of the female reproductive tract. The prevalence of ARID1A alterations in gynecologic precancers and cancers is summarized from the literature, and the putative mechanisms of tumor suppressive action examined both in benign/precursor lesions including endometriosis and atypical hyperplasia and in malignancies of the ovary, uterus, cervix and vagina. ARID1A alterations in gynecologic cancers are usually loss-of-function mutations, resulting in diminished or absent protein expression. ARID1A deficiency results in pleiotropic downstream effects related not only to its role in transcriptional regulation as a SWI/SNF complex subunit, but also related to the functions of ARID1A in DNA replication and repair, immune modulation, cell cycle progression, endoplasmic reticulum (ER) stress and oxidative stress. The most promising actionable signaling pathway interactions and therapeutic vulnerabilities of ARID1A mutated cancers are presented with a critical review of the currently available experimental and clinical evidence. The role of ARID1A in response to chemotherapeutic agents, radiation therapy and immunotherapy is also addressed. In summary, the multi-faceted role of ARID1A mutation in precancer and cancer is examined through a clinical lens focused on development of novel preventive and therapeutic interventions for gynecological cancers.

Tumors are a heterogeneous group of cell masses originating in various organs or tissues. The cellular composition of the tumor cell mass interacts in an intricate manner, influenced by humoral, genetic, molecular, and tumor microenvironment cues that dictate tumor growth or suppression. As a result, tumors undergo a period of a dormant state before their clinically discernible stage, which surpasses the clinical dormancy threshold. Moreover, as a genetically imprinted strategy, early-seeder cells, a distinct population of tumor cells, break off to dock nearby or extravasate into blood vessels to secondary tissues, where they form disseminated solitary dormant tumor cells with reversible capacity. Among the various mechanisms underlying the dormant tumor mass and dormant tumor cell formation, heat shock proteins (HSPs) might play one of the most important roles in how the dormancy program plays out. It is known that numerous aberrant cellular processes, such as malignant transformation, cancer cell stemness, tumor invasion, metastasis, angiogenesis, and signaling pathway maintenance, are influenced by the HSPs. An accumulating body of knowledge suggests that HSPs may be involved in the angiogenic switch, immune editing, and extracellular matrix (ECM) remodeling cascades, crucial genetically imprinted strategies important to the tumor dormancy initiation and dormancy maintenance program. In this review, we highlight the biological events that orchestrate the dormancy state and the body of work that has been conducted on the dynamics of HSPs in a tumor mass, as well as tumor cell dormancy and reactivation. Additionally, we propose a conceptual framework that could possibly underlie dormant tumor reactivation in metastatic relapse.

Ovarian cancer is a deadly female cancer with high rates of recurrence. The primary treatment strategy for patients is platinum-based therapy regimens that almost universally develop resistance. Consequently, new therapeutic avenues are needed to overcome the plateau that current therapies have on patient outcomes. We describe a gene amplification involving both HSF1 and MYC, wherein these two genes on chromosome 8q are co-amplified in over 7% of human tumors that is enriched to over 30% of patients with ovarian cancer. We further found that HSF1 and MYC transcriptional activity is correlated in human tumors and ovarian cancer cell lines, suggesting they may cooperate in ovarian cancer cells. CUT&RUN for HSF1 and MYC in co-amplified ovarian cancer cells revealed that HSF1 and MYC have overlapping binding at a substantial number of locations throughout the genome where their binding peaks are near identical. Consistent with these data, a protein-protein interaction between HSF1 and MYC was detected in ovarian cancer cells, implying these two transcription factors have a molecular cooperation. Further supporting their cooperation, growth of HSF1-MYC co-amplified ovarian cancer cells were found to be dependent on both HSF1 and MYC. In an attempt to identify a therapeutic target that could take advantage of this dependency on both HSF1 and MYC, PLK1 was identified as being correlated with HSF1 and MYC in primary human tumor specimens, consistent with a previously established effect of PLK1 on HSF1 and MYC protein levels. Targeting PLK1 with the compound volasertib (BI-6727) revealed a greater than 200-fold increased potency of volasertib in HSF1-MYC co-amplified ovarian cancer cells compared to ovarian cancer cells wild-type HSF1 and MYC copy number, which extended to several growth assays, including spheroid growth. Volasertib, and other PLK1 inhibitors, have not shown great success in clinical trials and this study suggests that targeting PLK1 may be viable in a precision medicine approach using HSF1-MYC co-amplification as a biomarker for response.

Heat shock proteins (HSPs) are molecular chaperones that play an important role in cellular protection against stress events and have been reported to be overexpressed in many cancers. The prognostic significance of HSPs and their regulatory factors, such as heat shock factor 1 (HSF1) and CHIP, are poorly understood.

To investigate the relationship between HSP expression and prognosis in esophageal and esophagogastric cancer.

A systematic review was conducted in accordance with PRISMA recommendations (PROSPERO: CRD42022370653), on Embase, PubMed, Cochrane, and LILACS. Cohort, case-control, and cross-sectional studies of patients with esophagus or esophagogastric cancer were included. HSP-positive patients were compared with HSP-negative, and the endpoints analyzed were lymph node metastasis, tumor depth, distant metastasis, and overall survival (OS). HSPs were stratified according to the HSP family, and the summary risk difference (RD) was calculated using a random-effect model.

The final selection comprised 27 studies, including esophageal squamous cell carcinoma (21), esophagogastric adenocarcinoma (5), and mixed neoplasms (1). The pooled sample size was 3465 patients. HSP40 and 60 were associated with a higher 3-year OS [HSP40: RD = 0.22; 95% confidence interval (CI): 0.09-0.35; HSP60: RD = 0.33; 95%CI: 0.17-0.50], while HSF1 was associated with a poor 3-year OS (RD = -0.22; 95%CI: -0.32 to -0.12). The other HSP families were not associated with long-term survival. HSF1 was associated with a higher probability of lymph node metastasis (RD = -0.16; 95%CI: -0.29 to -0.04). HSP40 was associated with a lower probability of lymph node dissemination (RD = 0.18; 95%CI: 0.03-0.33). The expression of other HSP families was not significantly related to tumor depth and lymph node or distant metastasis.

The expression levels of certain families of HSP, such as HSP40 and 60 and HSF1, are associated with long-term survival and lymph node dissemination in patients with esophageal and esophagogastric cancer.

Heat shock factors (HSFs) are the main transcriptional regulators of the evolutionarily conserved heat shock response. Beyond cell stress, several studies have demonstrated that HSFs also contribute to a vast variety of human pathologies, ranging from metabolic diseases to cancer and neurodegeneration. Despite their evident role in mitigating cellular perturbations, the functions of HSF1 and HSF2 in physiological proteostasis have remained inconclusive. Here, we analyzed a comprehensive selection of paraffin-embedded human tissue samples with immunohistochemistry. We demonstrate that both HSF1 and HSF2 display distinct expression and subcellular localization patterns in benign tissues. HSF1 localizes to the nucleus in all epithelial cell types, whereas nuclear expression of HSF2 was limited to only a few cell types, especially the spermatogonia and the urothelial umbrella cells. We observed a consistent and robust cytoplasmic expression of HSF2 across all studied smooth muscle and endothelial cells, including the smooth muscle cells surrounding the vasculature and the high endothelial venules in lymph nodes. Outstandingly, HSF2 localized specifically at cell-cell adhesion sites in a broad selection of tissue types, such as the cardiac muscle, liver, and epididymis. To the best of our knowledge, this is the first study to systematically describe the expression and localization patterns of HSF1 and HSF2 in benign human tissues. Thus, our work expands the biological landscape of these factors and creates the foundation for the identification of specific roles of HSF1 and HSF2 in normal physiological processes.

The Heat Shock Response (HSR) is a cellular stress reaction crucial for cell survival against stressors, including heat, in both healthy and cancer cells. Modulated electro-hyperthermia (mEHT) is an emerging non-invasive cancer therapy utilizing electromagnetic fields to selectively target cancer cells via temperature-dependent and independent mechanisms. However, mEHT triggers HSR in treated cells. Despite demonstrated efficacy in cancer treatment, understanding the underlying molecular mechanisms for improved therapeutic outcomes remains a focus. This review examines the HSR induced by mEHT in cancer cells, discussing potential strategies to modulate it for enhanced tumor-killing effects. Approaches such as HSF1 gene-knockdown and small molecule inhibitors like KRIBB11 are explored to downregulate the HSR and augment tumor destruction. We emphasize the impact of HSR inhibition on cancer cell viability, mEHT sensitivity, and potential synergistic effects, addressing challenges and future directions. This understanding offers opportunities for optimizing treatment strategies and advancing precision medicine in cancer therapy.

Triple-negative breast cancer (TNBC) is associated with a poor prognosis and metastatic growth. TNBC cells frequently undergo macroautophagy/autophagy, contributing to tumor progression and chemotherapeutic resistance. ANXA2 (annexin A2), a potential therapeutic target for TNBC, has been reported to stimulate autophagy. In this study, we investigated the role of ANXA2 in autophagic processes in TNBC cells. TNBC patients exhibited high levels of ANXA2, which correlated with poor outcomes. ANXA2 increased LC3B-II levels following bafilomycin A1 treatment and enhanced autophagic flux in TNBC cells. Notably, ANXA2 upregulated the phosphorylation of HSF1 (heat shock transcription factor 1), resulting in the transcriptional activation of ATG7 (autophagy related 7). The mechanistic target of rapamycin kinase complex 2 (MTORC2) played an important role in ANXA2-mediated ATG7 transcription by HSF1. MTORC2 did not affect the mRNA level of ANXA2, but it was involved in the protein stability of ANXA2. HSPA (heat shock protein family A (Hsp70)) was a potential interacting protein with ANXA2, which may protect ANXA2 from lysosomal proteolysis. ANXA2 knockdown significantly increased sensitivity to doxorubicin, the first-line chemotherapeutic regimen for TNBC treatment, suggesting that the inhibition of autophagy by ANXA2 knockdown may overcome doxorubicin resistance. In a TNBC xenograft mouse model, we demonstrated that ANXA2 knockdown combined with doxorubicin administration significantly inhibited tumor growth compared to doxorubicin treatment alone, offering a promising avenue to enhance the effectiveness of chemotherapy. In summary, our study elucidated the molecular mechanism by which ANXA2 modulates autophagy, suggesting a potential therapeutic approach for TNBC treatment.Abbreviation: ATG: autophagy related; ChIP: chromatin-immunoprecipitation; HBSS: Hanks' balanced salt solution; HSF1: heat shock transcription factor 1; MTOR: mechanistic target of rapamycin kinase; TNBC: triple-negative breast cancer; TFEB: transcription factor EB; TFE3: transcription factor binding to IGHM enhancer 3.

The stress-associated molecular chaperone system is an actionable target in cancer therapies. It is ubiquitously upregulated in cancer tissues and enables tumorigenicity by stabilizing hundreds of oncoproteins and disturbing the stoichiometry of protein complexes. Most inhibitors target the key component heat-shock protein 90 (HSP90). However, although classical HSP90 inhibitors are highly tumor-selective, they fail in phase 3 clinical oncology trials. These failures are at least partly due to an interference with a negative feedback loop by HSP90 inhibition, known as heat-shock response (HSR): in response to HSP90 inhibition there is compensatory synthesis of stress-inducible chaperones, mediated by the transcription factor heat-shock factor 1 (HSF1). We recently identified that wildtype p53 (p53) actively reduces the HSR by repressing HSF1 via a p21-CDK4/6-MAPK-HSF1 axis. Here we test the hypothesis that in HSP90-based therapies simultaneous p53 activation or direct cell cycle inhibition interrupts the deleterious HSF1-HSR axis and improves the efficiency of HSP90 inhibitors. Indeed, we find that the clinically relevant p53 activator Idasanutlin suppresses the HSF1-HSR activity in HSP90 inhibitor-based therapies. This combination synergistically reduces cell viability and accelerates cell death in p53-proficient colorectal cancer (CRC) cells, murine tumor-derived organoids and patient-derived organoids (PDOs). Mechanistically, upon combination therapy human CRC cells strongly upregulate p53-associated pathways, apoptosis, and inflammatory immune pathways. Likewise, in the chemical AOM/DSS CRC model in mice, dual HSF1-HSP90 inhibition strongly represses tumor growth and remodels immune cell composition, yet displays only minor toxicities in mice and normal mucosa-derived organoids. Importantly, inhibition of the cyclin dependent kinases 4 and 6 (CDK4/6) under HSP90 inhibition phenocopies synergistic repression of the HSR in p53-proficient CRC cells. Even more important, in p53-deficient (mutp53-harboring) CRC cells, an HSP90 inhibition in combination with CDK4/6 inhibitors similarly suppresses the HSF1-HSR system and reduces cancer growth. Likewise, p53-mutated PDOs strongly respond to dual HSF1-HSP90 pathway inhibition and thus, providing a strategy to target CRC independent of the p53 status. In sum, activating p53 (in p53-proficient cancer cells) or inhibiting CDK4/6 (independent of the p53 status) provide new options to improve the clinical outcome of HSP90-based therapies and to enhance colorectal cancer therapy.

Zokors, an Asiatic group of subterranean rodents, originated in lowlands and colonized high-elevational zones following the uplift of the Qinghai-Tibet plateau about 3.6 million years ago. Zokors live at high elevation in subterranean burrows and experience hypobaric hypoxia, including both hypoxia (low oxygen concentration) and hypercapnia (elevated partial pressure of CO2). Here we report a genomic analysis of six zokor species (genus Eospalax) with different elevational ranges to identify structural variants (deletions and inversions) that may have contributed to high-elevation adaptation. Based on an assembly of a chromosome-level genome of the high-elevation species, Eospalax baileyi, we identified 18 large inversions that distinguished this species from congeners native to lower elevations. Small-scale structural variants in the introns of EGLN1, HIF1A, HSF1 and SFTPD of E. baileyi were associated with the upregulated expression of those genes. A rearrangement on chromosome 1 was associated with altered chromatin accessibility, leading to modified gene expression profiles of key genes involved in the physiological response to hypoxia. Multigene families that underwent copy-number expansions in E. baileyi were enriched for autophagy, HIF1 signalling and immune response. E. baileyi show a significantly larger lung mass than those of other Eospalax species. These findings highlight the key role of structural variants underlying hypoxia adaptation of high-elevation species in Eospalax.

Heat shock factor 1 (HSF1) is a stress-responsive transcription factor that promotes cancer cell malignancy. To provide a better understanding of the biological processes regulated by HSF1, here we developed an HSF1 activity signature (HAS) and found that it was negatively associated with antitumor immune cells in breast tumors. Knockdown of HSF1 decreased breast tumor size and caused an influx of several antitumor immune cells, most notably CD8+ T cells. Depletion of CD8+ T cells rescued the reduction in growth of HSF1-deficient tumors, suggesting HSF1 prevents CD8+ T-cell influx to avoid immune-mediated tumor killing. HSF1 suppressed expression of CCL5, a chemokine for CD8+ T cells, and upregulation of CCL5 upon HSF1 loss significantly contributed to the recruitment of CD8+ T cells. These findings indicate that HSF1 suppresses antitumor immune activity by reducing CCL5 to limit CD8+ T-cell homing to breast tumors and prevent immune-mediated destruction, which has implications for the lack of success of immune modulatory therapies in breast cancer.

The stress-responsive transcription factor HSF1 reduces CD8+ T-cell infiltration in breast tumors to prevent immune-mediated killing, indicating that cellular stress responses affect tumor-immune interactions and that targeting HSF1 could improve immunotherapies.

Cells maintain homeostasis via dynamic regulation of stress response pathways. Stress pathways transiently induce response regulons via negative feedback loops, but the extent to which individual genes provide feedback has not been comprehensively measured for any pathway. Here, we disrupted induction of each gene in the Saccharomyces cerevisiae heat shock response (HSR) and quantified cell growth and HSR dynamics following heat shock. The screen revealed a core feedback loop governing expression of the chaperone Hsp70 reinforced by an auxiliary feedback loop controlling Hsp70 subcellular localization. Mathematical modeling and live imaging demonstrated that multiple HSR targets converge to promote Hsp70 nuclear localization via its release from cytosolic condensates. Following ethanol stress, a distinct set of factors similarly converged on Hsp70, suggesting that nonredundant subsets of the HSR regulon confer feedback under different conditions. Flexible spatiotemporal feedback loops may broadly organize stress response regulons and expand their adaptive capacity.

It was reported that lowly expressed RING1 indicates poor prognosis in breast cancer (BC) patients, while the mechanism by which RING1 is involved in BC progression is not fully understood. Here, we found that RING1 was lowly expressed in BC tissues and cells than in normal mammary tissues and epithelial cells. Overexpression of RING1 suppressed the cell proliferative and colony formation abilities, and facilitated cell cycle arrest and cell apoptosis in BC cells (T47D and MCF-7 cells). Mechanistically, as an ubiquitin ligase, RING1 bound to HSF1 and induced its proteasome-dependent degradation. HSF1 could bind to the promoter region of MT2A to promote the transcriptional level of MT2A. While RING1 overexpression hindered the transcriptional activation of MT2A induced by HSF1. Moreover, ectopic expression of MT2A reversed the inhibitory effect of RING1 on cell proliferation and clonogenesis, and antagonized the promotion effect of RING1 on cell cycle arrest and apoptosis in BC cells. Additionally, T47D cells infected with or without lentivirus-mediated RING1 overexpression vector (LV-RING1) were injected subcutaneously into the right back of nude mice to evaluate tumorigenicity. And overexpression of RING1 impeded the growth of BC xenografts in mice. In conclusion, RING1 suppressed the transcriptional activation of MT2A induced by HSF1 by facilitating the ubiquitination degradation of HSF1, resulting in cell cycle arrest and apoptosis in BC cells.

Cadmium toxicity has been associated with disruption of protein homeostasis by interfering with protein folding processes. Heat shock factor 1 (HSF1) coordinates the rapid and extensive cellular response to maintain proteomic balance facing the challenges from many environmental stressors. Thus, we suspect that HSF1 may shield cells from cadmium toxicity by conserving proteome integrity.

Here, we demonstrate that cadmium, a highly poisonous metal, induces aggregation of cytosolic proteins in human cells, which disrupts protein homeostasis and activates HSF1. Cadmium exposure increases HSF1's phosphorylation, nuclear translocation and DNA bindings. Aside from this, HSF1 goes through liquid-liquid phase separation to form small nuclear condensates upon cadmium exposure. A specific regulatory domain of HSF1 is critical for HSF1's phase separation capability. Most importantly, human cells with impaired HSF1 are sensitized to cadmium, however, cells with overexpressed HSF1 are protected from cadmium toxicity. Overexpression of HSF1 in human cells reduces protein aggregates, amyloid fibrils and DNA damages to antagonize cadmium toxicity.

HSF1 protects cells from cadmium toxicity by governing the integrity of both proteome and genome. Similar mechanisms may enable HSF1 to alleviate cellular toxicity caused by other heavy metals. HSF1's role in cadmium exposure may provide important insights into the toxic effects of heavy metals on human cells and body organs, allowing us to better manage heavy metal poisoning.

Heat shock factor 1 (HSF1) is a transcription factor crucial for regulating heat shock response (HSR), one of the significant cellular protective mechanisms. When cells are exposed to proteotoxic stress, HSF1 induces the expression of heat shock proteins (HSPs) to act as chaperones, correcting the protein-folding process and maintaining proteostasis. In addition to its role in HSR, HSF1 is overexpressed in multiple cancer cells, where its activation promotes malignancy and leads to poor prognosis. The mechanisms of HSF1-induced tumorigenesis are complex and involve diverse signaling pathways, dependent on cancer type. With its important roles in tumorigenesis and tumor progression, targeting HSF1 offers a novel cancer treatment strategy. In this article, we examine the basic function of HSF1 and its regulatory mechanisms, focus on the mechanisms involved in HSF1's roles in different cancer types, and examine current HSF1 inhibitors as novel therapeutics to treat cancers.

Heat shock proteins (HSPs) represent cellular chaperones that are classified into several families, including HSP27, HSP40, HSP60, HSP70, and HSP90. The role of HSPs in the cell includes the facilitation of protein folding and maintaining protein structure. Both processes play crucial roles during stress conditions in the cell such as heat shock, degradation, and hypoxia. Moreover, HSPs are important modulators of cellular proliferation and differentiation, and are strongly associated with the molecular orchestration of carcinogenesis. The expression and/or activity of HSPs in cancer cells is generally abnormally high and is associated with increased metastatic potential and activity of cancer stem cells, more pronounced angiogenesis, downregulated apoptosis, and the resistance to anticancer therapy in many patients. Based on the mentioned reasons, HSPs have strong potential as valid diagnostic, prognostic, and therapeutic biomarkers in clinical oncology. In addition, numerous papers describe the role of HSPs as chaperones in the regulation of immune responses inside and outside the cell. Importantly, highly expressed/activated HSPs may be inhibited via immunotherapeutic targets in various types of cancers. The aim of this work is to provide a comprehensive overview of the relationship between HSPs and the tumor cell with the intention of highlighting the potential use of HSPs in personalized cancer management.

The heat shock protein 90 (Hsp90) is a protein involved in many different biological processes and especially in cell survival. Some of these functions require the participation of other biological molecules, so Hsp90 is a chaperone that takes part in many protein-protein interactions working as a critical signaling hub protein. As a member of the heat shock protein family, Hsp90 expression is regulated under certain environmental and/or stressful situations, therefore Hsp90 concentration can be monitored and linked to these effects.

This review discusses the Hsp90 expression in samples from individuals affected by different diseases (from infectious to cancer origin), and the biological consequences of these disorders, including the potential use of Hsp90 as a biomarker for the diagnosis of human diseases.

The potential of Hsp90 as a biomarker disease has been demonstrated in several studies in relation to infectious diseases and especially cancer. However, further research in this field is still needed, mainly to validate in statistically significant clinical studies that the detection of Hsp90 protein allows the diagnosis of some cancers at an early stage and also that it can act as a biomarker for monitoring the efficacy of their therapies.

CCT251236 1, a potent chemical probe, was previously developed from a cell-based phenotypic high-throughput screen (HTS) to discover inhibitors of transcription mediated by HSF1, a transcription factor that supports malignancy. Owing to its activity against models of refractory human ovarian cancer, 1 was progressed into lead optimization. The reduction of P-glycoprotein efflux became a focus of early compound optimization; central ring halogen substitution was demonstrated by matched molecular pair analysis to be an effective strategy to mitigate this liability. Further multiparameter optimization led to the design of the clinical candidate, CCT361814/NXP800 22, a potent and orally bioavailable fluorobisamide, which caused tumor regression in a human ovarian adenocarcinoma xenograft model with on-pathway biomarker modulation and a clean in vitro safety profile. Following its favorable dose prediction to human, 22 has now progressed to phase 1 clinical trial as a potential future treatment for refractory ovarian cancer and other malignancies.

Phosphorylation of proteins is reversibly controlled by the kinases and phosphatases in many posttranslational regulation patterns. Protein phosphatase 5 (PPP5C) is a serine/threonine protein phosphatase showing dual function by simultaneously exerting dephosphorylation and co-chaperone functions. Due to this special role, PPP5C was found to participate in many signal transductions related to various diseases. Abnormal expression of PPP5C results in cancers, obesity, and Alzheimer's disease, making it a potential drug target. However, the design of small molecules targeting PPP5C is struggling due to its special monomeric enzyme form and low basal activity by a self-inhibition mechanism. Through realizing the PPP5C's dual function as phosphatase and co-chaperone, more and more small molecules were found to regulate PPP5C with a different mechanism. This review aims to provide insights into PPP5C's dual function from structure to function, which could provide efficient design strategies for small molecules targeting PPP5C as therapeutic candidates.

Pseudouridylation is one of the most abundant RNA modifications in eukaryotes, making pseudouridine known as the "fifth nucleoside." This highly conserved alteration affects all non-coding and coding RNA types. Its role and importance have been increasingly widely researched, especially considering that its absence or damage leads to serious hereditary diseases. Here, we summarize the human genetic disorders described to date that are related to the participants of the pseudouridylation process.

Preserving proteostasis is a major survival mechanism for cancer. Dual specificity tyrosine phosphorylation-regulated kinase 2 (DYRK2) is a key oncogenic kinase that directly activates the transcription factor heat-shock factor 1 (HSF1) and the 26S proteasome. Targeting DYRK2 has proven to be a tractable strategy to target cancers sensitive to proteotoxic stress; however, the development of HSF1 inhibitors remains in its infancy. Importantly, multiple other kinases have been shown to redundantly activate HSF1 that promoted ideas to directly target HSF1. The eventual development of direct HSF1 inhibitor KRIBB11 suggests that the transcription factor is indeed a druggable target. The current study establishes that concurrent targeting of HSF1 and DYRK2 can indeed impede cancer by inducing apoptosis faster than individual targetting. Furthermore, targeting the DYRK2-HSF1 axis induces death in proteasome inhibitor-resistant cells and reduces triple-negative breast cancer (TNBC) burden in ectopic and orthotopic xenograft models. Together the data indicate that cotargeting of kinase DYRK2 and its substrate HSF1 could prove to be a beneficial strategy in perturbing neoplastic malignancies.

Heat shock protein 90 (Hsp90) is a dynamic protein which serves to ensure proper folding of nascent client proteins, regulate transcriptional responses to environmental stress and guide misfolded and damaged proteins to destruction via ubiquitin proteasome pathway. Recent advances in the field of Hsp90 have been made through development of isoform selective inhibitors, Hsp90 C-terminal inhibitors and disruption of protein-protein interactions. These approaches have led to alleviation of adverse off-target effects caused by pan-inhibition of Hsp90 using N-terminal inhibitors. In this review, we provide an overview of relevant advances on targeting the Hsp90 C-terminal Domain (CTD) and the development of Hsp90 C-terminal inhibitors (CTIs) since 2015.

We recently identified a cell-of-origin-specific mRNA signature associated with metastasis and poor outcome in triple-negative carcinoma (TNBC). This TNBC cell-of-origin signature is associated with the over-expression of histone deacetylases and zinc finger protein HDAC1, HDAC7, and ZNF92, respectively. Based on this signature, we discovered that the combination of three drugs (an HDAC inhibitor, an anti-helminthic Niclosamide, and an antibiotic Tanespimycin that inhibits HSP90) synergistically reduces the proliferation of the twelve tested TNBC cell lines. Additionally, we discovered that four out of five inflammatory breast carcinoma cell lines are sensitive to this combination. Significantly, the concentration of the drugs that are used in these experiments are within or below clinically achievable dose, and the synergistic activity only emerged when all three drugs were combined. Our results suggest that HDAC and HSP90 inhibitors combined with the tapeworm drug Niclosamide can achieve remarkably synergistic inhibition of TNBC and IBC. Since Niclosamide, HDAC, and HSP90 inhibitors were approved for clinical use for other cancer types, it may be possible to repurpose their combination for TNBC and IBC.

Application of microRNA-mediated mRNA expression in treatment of diverse cancers has been documented. The current study was explored to study the role of miR-217 in breast cancer (BC) progression and the related downstream factors. Clinical tissue samples, BC cell lines and the established xenograft models were prepared for ectopic expression and depletion experiments to discern the regulatory roles of miR-217-mediated NF1 in BC cell proliferation, metastasis and chemoresistance as well as tumorigenic ability of BC cells in nude mice. miR-217 was upregulated in BC, which was a predictor of poor prognosis of BC patients. NF1 could be targeted by miR-217. miR-217 promoted malignant characteristics of BC cells through enhancing ATF3-MMP13 interaction by inhibiting NF1. miR-217 repressed sensitivity against anti-cancer drugs by inducing autophagy of BC cells through the NF1/HSF1/ATG7 axis. Also, miR-217 could inhibit NF1 to facilitate tumorigenic ability of BC cells in vivo. Our study emphasized that miR-217 could potentially inhibit NF1 expression to activate the c-Jun, thus enhancing the expression and interaction of ATF3/MMP13 and promoting the malignant features of BC cells. Furthermore, miR-217 conferred chemoresistance on BC by enhancing BC cell autophagy, which was achieved by limiting NF1 expression to induce the HSF1/ATG7 pathway.

Heat shock factor 1 (HSF1) is the master transcriptional regulator of the heat shock response (HSR) in mammalian cells and is a critical element in maintaining protein homeostasis. HSF1 functions at the center of many physiological processes like embryogenesis, metabolism, immune response, aging, cancer, and neurodegeneration. However, the mechanisms that allow HSF1 to control these different biological and pathophysiological processes are not fully understood. This review focuses on Huntington's disease (HD), a neurodegenerative disease characterized by severe protein aggregation of the huntingtin (HTT) protein. The aggregation of HTT, in turn, leads to a halt in the function of HSF1. Understanding the pathways that regulate HSF1 in different contexts like HD may hold the key to understanding the pathomechanisms underlying other proteinopathies. We provide the most current information on HSF1 structure, function, and regulation, emphasizing HD, and discussing its potential as a biological target for therapy.

We performed PubMed search to find established and recent reports in HSF1, heat shock proteins (Hsp), HD, Hsp inhibitors, HSF1 activators, and HSF1 in aging, inflammation, cancer, brain development, mitochondria, synaptic plasticity, polyglutamine (polyQ) diseases, and HD.

Research and review articles that described the mechanisms of action of HSF1 were selected based on terms used in PubMed search.

HSF1 plays a crucial role in the progression of HD and other protein-misfolding related neurodegenerative diseases. Different animal models of HD, as well as postmortem brains of patients with HD, reveal a connection between the levels of HSF1 and HSF1 dysfunction to mutant HTT (mHTT)-induced toxicity and protein aggregation, dysregulation of the ubiquitin-proteasome system (UPS), oxidative stress, mitochondrial dysfunction, and disruption of the structural and functional integrity of synaptic connections, which eventually leads to neuronal loss. These features are shared with other neurodegenerative diseases (NDs). Currently, several inhibitors against negative regulators of HSF1, as well as HSF1 activators, are developed and hold promise to prevent neurodegeneration in HD and other NDs.

Understanding the role of HSF1 during protein aggregation and neurodegeneration in HD may help to develop therapeutic strategies that could be effective across different NDs.

Heat shock protein 90 (Hsp90) has been an important therapeutic target for cancer therapy for decades. Unexpectedly, the monotherapy of N-terminal Hsp90 inhibitor STA9090 related clinical trials halted in phase III, and metastases were reported in animal models with the treatment of N-terminal Hsp90 inhibitors. Vacuolar protein sorting-associated protein 35 (VPS35) plays a vital role in endosome-derived EV (extracellular vesicle) traffic in neurodegeneration diseases, but no vps35 related EV were reported in tumors till now. Since tumor derived EVs contributes to metastasis and VPS35 is recently found to be involved in the invasion and metastasis of hepatocellular carcinoma (HCC), whether N-terminal Hsp90 inhibitor STA9090 induced EVs generation and the role of VPS35 in it were explored in this study. We found that N-terminal Hsp90 inhibitor STA9090 upregulated Bclaf1 and VPS35 levels, increased the secretion of EVs, and STA9090-induced-EVs promoted the invasion of HepG2 cells. As the clinical data suggested that the increased Bclaf1 and VPS35 levels correlated with increased metastasis and poorer prognosis in HCC, we focused on the Bclaf1-VPS35-EVs axis to further explore the mechanism of VPS35-related metastasis. The results demonstrated that Bclaf1 facilitated the transcription of VPS35 via bZIP domain, and knockdown of Bclaf1 or VPS35 alleviated pro-metastatic capability of STA9090-induced-EVs. All the results revealed the role of Bclaf1-VPS35-EVs axis on metastasis of HCC, and VPS35 knockdown decreased Hsp90 Inhibitor STA9090 induced extracellular vesicle release and metastasis, which provided a new combination therapeutic strategy to inhibit the metastasis of HCC caused by N-terminal Hsp90 inhibitor induced extracellular vesicles.

The heat-shock factors (HSFs) belong to an evolutionary conserved family of transcription factors that were discovered already over 30 years ago. The HSFs have been shown to a have a broad repertoire of target genes, and they also have crucial functions during normal development. Importantly, HSFs have been linked to several disease states, such as neurodegenerative disorders and cancer, highlighting their importance in physiology and pathology. However, it is still unclear how HSFs are regulated and how they choose their specific target genes under different conditions. Posttranslational modifications and interplay among the HSF family members have been shown to be key regulatory mechanisms for these transcription factors. In this review, we focus on the mammalian HSF1 and HSF2, including their interplay, and provide an updated overview of the advances in understanding how HSFs are regulated and how they function in multiple processes of development, aging, and disease. We also discuss HSFs as therapeutic targets, especially the recently reported HSF1 inhibitors.

Acute myeloid leukemia (AML) is maintained by self-renewing leukemic stem cells (LSCs). A fundamental problem in treating AML is that conventional therapy fails to eliminate LSCs, which can reinitiate leukemia. Heat shock transcription factor 1 (HSF1), a central regulator of the stress response, has emerged as an important target in cancer therapy. Using genetic Hsf1 deletion and a direct HSF1 small molecule inhibitor, we show that HSF1 is specifically required for the maintenance of AML, while sparing steady-state and stressed hematopoiesis. Mechanistically, deletion of Hsf1 dysregulates multifaceted genes involved in LSC stemness and suppresses mitochondrial oxidative phosphorylation through downregulation of succinate dehydrogenase C (SDHC), a direct HSF1 target. Forced expression of SDHC largely restores the Hsf1 ablation-induced AML developmental defect. Importantly, the growth and engraftment of human AML cells are suppressed by HSF1 inhibition. Our data provide a rationale for developing efficacious small molecules to specifically target HSF1 in AML.

Disrupted circadian rhythmicity is a prominent feature of modern society and has been designated as a probable carcinogen by the World Health Organization. However, the biological mechanisms that connect circadian disruption and cancer risk remain largely undefined. We demonstrate that exposure to chronic circadian disruption [chronic jetlag (CJL)] increases tumor burden in a mouse model of KRAS-driven lung cancer. Molecular characterization of tumors and tumor-bearing lung tissues revealed that CJL enhances the expression of heat shock factor 1 (HSF1) target genes. Consistently, exposure to CJL disrupted the highly rhythmic nuclear trafficking of HSF1 in the lung, resulting in an enhanced accumulation of HSF1 in the nucleus. HSF1 has been shown to promote tumorigenesis in other systems, and we find that pharmacological or genetic inhibition of HSF1 reduces the growth of KRAS-mutant human lung cancer cells. These findings implicate HSF1 as a molecular link between circadian disruption and enhanced tumorigenesis.

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