Gene Summary

Gene:HSF1; heat shock transcription factor 1
Aliases: HSTF1
Summary:The product of this gene is a transcription factor that is rapidly induced after temperature stress and binds heat shock promoter elements (HSE). This protein plays a role in the regulation of lifespan. Expression of this gene is repressed by phsphorylation, which promotes binding by heat shock protein 90. [provided by RefSeq, Aug 2016]
Databases:VEGA, OMIM, HGNC, Ensembl, GeneCard, Gene
Protein:heat shock factor protein 1
Source:NCBIAccessed: 15 March, 2017


What does this gene/protein do?
Show (18)

Cancer Overview

Research Indicators

Publications Per Year (1992-2017)
Graph generated 15 March 2017 using data from PubMed using criteria.

Literature Analysis

Mouse over the terms for more detail; many indicate links which you can click for dedicated pages about the topic.

  • Gene Expression Regulation
  • Drug Resistance
  • Cell Line
  • ras Proteins
  • Hepatocellular Carcinoma
  • DNA-Binding Proteins
  • Signal Transduction
  • Protein Binding
  • Melanoma
  • HeLa Cells
  • Antineoplastic Agents
  • Transcription Factors
  • Gene Expression
  • Base Sequence
  • Western Blotting
  • Apoptosis
  • Cell Survival
  • Breast Cancer
  • Cancer Gene Expression Regulation
  • Liver Cancer
  • siRNA
  • HSP70 Heat-Shock Proteins
  • Heat-Shock Response
  • Neoplastic Cell Transformation
  • Phenotype
  • RNA Interference
  • Molecular Sequence Data
  • Hot Temperature
  • Heat-Shock Proteins
  • Promoter Regions
  • Mutation
  • Knockout Mice
  • Cell Proliferation
  • Neoplasm Proteins
  • HSP90 Heat-Shock Proteins
  • Chromosome 8
  • Intracellular Signaling Peptides and Proteins
  • Messenger RNA
  • Phosphorylation
Tag cloud generated 15 March, 2017 using data from PubMed, MeSH and CancerIndex

Specific Cancers (3)

Data table showing topics related to specific cancers and associated disorders. Scope includes mutations and abnormal protein expression.

Note: list is not exhaustive. Number of papers are based on searches of PubMed (click on topic title for arbitrary criteria used).

Latest Publications: HSF1 (cancer-related)

Eiro N, Fernandez-Gomez J, Sacristán R, et al.
Stromal factors involved in human prostate cancer development, progression and castration resistance.
J Cancer Res Clin Oncol. 2017; 143(2):351-359 [PubMed] Related Publications
PURPOSE: To detect new predictive markers from the prostate cancer tissue, to study the expression by cultured cancer-associated fibroblasts (CAFs) of stromal factors implicated in prostate carcinogenesis, and to compare their expressions in localized, metastatic, castration-sensitive (CSCP), castration-resistant prostate tumors (CRCP) as well as in fibroblasts from benign prostatic hyperplasia (BPH).
MATERIALS AND METHODS: The genomic expression of 20 stroma-derived factors, including the androgen receptor (AR), growth factors (FGF2, FGF7, FGF10, HGF, TGFβ, PDGFB), protein implicated in invasion (MMP-2, MMP-9 and MMP-11), inflammation (IL-6, IL-17, STAT-3 and NFκB), stroma/epithelium interaction (CDH11, FAP, CXCL12 and CXCL14) and chaperones (HPA1A and HSF1), was evaluated in cultured fibroblasts both from BHP and prostate carcinomas (PCa). After isolation and culture of fibroblasts by biopsy specimens, RNA was isolated and genomic studies performed.
RESULTS: Finally, 5 BPH and 37 PCa specimens were selected: clinically localized (19), metastatic (5), CSCP (7) and CRPC (6). Interleukin-17 receptor (IL-17RB) was highly expressed in CAFs compared with fibroblasts from BPH. However, metalloproteinase-2 and chemokine ligand 14 (CXCL14) were expressed at higher levels by fibroblasts from BPH. The fibroblastic growth factor-7 was highly expressed by CAFs from localized tumors, but metalloproteinase-11 in metastatic tumors. MMP-11, androgen receptor (AR) and heat-shock-70kda-protein-1A (HSPA1A) expressions were significantly higher in CAFs from CRPC.
CONCLUSIONS: These results demonstrate a CAFs heterogeneity among prostate carcinomas with regard to some molecular profile expressions that may be relevant in tumor development (IL-17RB), progression (MMP-11) and castration resistance (AR, MMP-11 and HSPA1A).

Calderwood SK, Neckers L
Hsp90 in Cancer: Transcriptional Roles in the Nucleus.
Adv Cancer Res. 2016; 129:89-106 [PubMed] Related Publications
Hsp90 plays a key role in fostering metabolic pathways essential in tumorigenesis through its functions as a molecular chaperone. Multiple oncogenic factors in the membrane and cytoplasm are thus protected from degradation and destruction. Here, we have considered Hsp90's role in transcription in the nucleus. Hsp90 functions both in regulating the activity of sequence-specific transcription factors such as nuclear receptors and HSF1, as well as impacting more globally acting factors that act on chromatin and RNA polymerase II. Hsp90 influences transcription by modulating histone modification mediated by its clients SMYD3 and trithorax/MLL, as well as by regulating the processivity of RNA polymerase II through negative elongation factor. It is not currently clear how the transcriptional role of Hsp90 may be influenced by the cancer milieu although recently discovered posttranslational modification of the chaperone may be involved. Dysregulation of Hsp90 may thus influence malignant processes both by modulating the function of specific transcription factors and effects on more globally acting general components of the transcriptional machinery.

Asano Y, Kawase T, Okabe A, et al.
IER5 generates a novel hypo-phosphorylated active form of HSF1 and contributes to tumorigenesis.
Sci Rep. 2016; 6:19174 [PubMed] Free Access to Full Article Related Publications
The transcription factors HSF1 and p53 both modulate the stress response, thereby protecting and facilitating the recovery of stressed cells, but both have the potential to promote tumor development. Here we show that a p53 target gene, IER5, encodes an activator of HSF1. IER5 forms a ternary complex with HSF1 and the phosphatase PP2A, and promotes the dephosphorylation of HSF1 at numbers of serine and threonine residues, generating a novel, hypo-phosphorylated active form of HSF1. IER5 is also transcriptionally upregulated in various cancers, although this upregulation is not always p53-dependent. The IER5 locus is associated with a so-called super enhancer, frequently associated with hyperactivated oncogenes in cancer cell lines. Enhanced expression of IER5 induces abnormal HSF1 activation in cancer cells and contributes to the proliferation of these cells under stressed conditions. These results reveal the existence of a novel IER5-mediated cancer regulation pathway that is responsible for the activation of HSF1 observed in various cancers.

Kim HB, Lee SH, Um JH, et al.
Sensitization of multidrug-resistant human cancer cells to Hsp90 inhibitors by down-regulation of SIRT1.
Oncotarget. 2015; 6(34):36202-18 [PubMed] Free Access to Full Article Related Publications
The effectiveness of Hsp90 inhibitors as anticancer agents was limited in multidrug-resistant (MDR) human cancer cells due to induction of heat shock proteins (Hsps) such as Hsp70/Hsp27 and P-glycoprotein (P-gp)-mediated efflux. In the present study, we showed that resistance to Hsp90 inhibitors of MDR human cancer cells could be overcome with SIRT1 inhibition. SIRT1 knock-down or SIRT1 inhibitors (amurensin G and EX527) effectively suppressed the resistance to Hsp90 inhibitors (17-AAG and AUY922) in several MDR variants of human lymphoblastic leukemia and human breast cancer cell lines. SIRT1 inhibition down-regulated the expression of heat shock factor 1 (HSF1) and subsequently Hsps and facilitated Hsp90 multichaperone complex disruption via hyperacetylation of Hsp90/Hsp70. These findings were followed by acceleration of ubiquitin ligase CHIP-mediated mutant p53 (mut p53) degradation and subsequent down-regulation of P-gp in 17-AAG-treated MDR cancer cells expressing P-gp and mut p53 after inhibition of SIRT1. Therefore, combined treatment with Hsp90 inhibitor and SIRT1 inhibitor could be a more effective therapeutic approach for Hsp90 inhibitor-resistant MDR cells via down-regulation of HSF1/Hsps, mut p53 and P-gp.

Davies AE, Kortright K, Kaplan KB
Adenomatous polyposis coli mutants dominantly activate Hsf1-dependent cell stress pathways through inhibition of microtubule dynamics.
Oncotarget. 2015; 6(28):25202-16 [PubMed] Free Access to Full Article Related Publications
Cancer cells up-regulate cell stress pathways, including the protein chaperone Hsp90. Increases in Hsp90 are believed "buffer" mutant protein activities necessary for cancer phenotypes. Activation of the cell stress pathway also alters the transcriptional landscape of cells in ways that are critical for cancer progression. However, it is unclear when and how the cell stress pathway is de-regulated during cancer progression. Here we report that mutations in adenomatous polyposis coli (APC) found in colorectal cancer activate cell stress pathways in mouse intestinal crypt cells, prior to loss of heterozygosity at APC or to the appearance of canonical intestinal cancer markers. Hsp90 levels are elevated in normal APC heterozygote crypt cells and further elevated in non-cancer cells adjacent to dysplasias, suggesting that the Hsp90 stress pathway marks the "cancer-field" effect. Expression of mutant APC in normal human epithelial cells is sufficient to activate a cell stress pathway via perturbations in microtubule dynamics. Inhibition of microtubule dynamics is sufficient to activate an Hsf1-dependent increase in gene transcription and protein levels. We suggest that the early activation of this Hsf1 dependent cell stress pathway by mono-allelic mutations in APC can affect cell programming in a way that contributes to cancer onset.

Wang B, Lee CW, Witt A, et al.
Heat shock factor 1 induces cancer stem cell phenotype in breast cancer cell lines.
Breast Cancer Res Treat. 2015; 153(1):57-66 [PubMed] Free Access to Full Article Related Publications
Heat shock factor 1 (HSF1) has long been recognized as the master transcription factor that regulates heat shock proteins (HSPs).  More recently HSF1 has been associated with a broader role in regulating response to a variety of cellular stresses beyond heat-shock.  We previously found that high HSF1 expression is associated with poor outcome in lung, breast and colon cancers. Importantly, however, the HSF1 signature correlated with poor outcome in these studies was not related to the heat shock response, which suggested that tumor outcome associated with high HSF expression may be due to processes other than stress response. Hence, we explored the question whether high HSF1 expression might be associated with the cancer stem cell (CSC) phenotype. To do so, we examined the association of HSF1 with CSC phenotype by FACS and immunofluorescence. In addition, we evaluated the effects of HSF1 over-expression and knock-down on sphere formation and CSC marker expression in breast cancer cell lines. Here, we report results demonstrating that high HSF1 not only correlates with CSC marker expression, but inducible HSF1 over-expression augments and HSF1 knock-down inhibits CSC phenotype. Furthermore, HSF1 expression confers resistance to chemotherapeutic drugs and increases CSC frequency. In conclusion, our study indicates that one of the potential HSP-independent HSF1 driven mechanisms that may contribute to poor outcome in human tumors involves regulation of the CSC phenotype. Hence, therapeutic inhibition of HSF1 may be one route to target CSCs in human tumors.

Ding M, Li R, He R, et al.
p53 activated by AND gate genetic circuit under radiation and hypoxia for targeted cancer gene therapy.
Cancer Sci. 2015; 106(9):1163-73 [PubMed] Free Access to Full Article Related Publications
Radio-activated gene therapy has been developed as a novel therapeutic strategy against cancer; however, expression of therapeutic gene in peritumoral tissues will result in unacceptable toxicity to normal cells. To restrict gene expression in targeted tumor mass, we used hypoxia and radiation tolerance features of tumor cells to develop a synthetic AND gate genetic circuit through connecting radiation sensitivity promoter cArG6 , heat shock response elements SNF1, HSF1 and HSE4 with retroviral vector plxsn. Their construction and dynamic activity process were identified through downstream enhanced green fluorescent protein and wtp53 expression in non-small cell lung cancer A549 cells and in a nude mice model. The result showed that AND gate genetic circuit could be activated by lower required radiation dose (6 Gy) and after activated, AND gate could induce significant apoptosis effects and growth inhibition of cancer cells in vitro and in vivo. The radiation- and hypoxia-activated AND gate genetic circuit, which could lead to more powerful target tumoricidal activity represented a promising strategy for both targeted and effective gene therapy of human lung adenocarcinoma and low dose activation character of the AND gate genetic circuit implied that this model could be further exploited to decrease side-effects of clinical radiation therapy.

Lee JH, Lee YK, Lim JJ, et al.
Mitochondrial Respiratory Dysfunction Induces Claudin-1 Expression via Reactive Oxygen Species-mediated Heat Shock Factor 1 Activation, Leading to Hepatoma Cell Invasiveness.
J Biol Chem. 2015; 290(35):21421-31 [PubMed] Free Access to Full Article Related Publications
Although mitochondrial dysfunction has been implicated in tumor metastasis, it is unclear how it regulates tumor cell aggressiveness. We have reported previously that human hepatoma cells harboring mitochondrial defects have high tumor cell invasion activity via increased claudin-1 (Cln-1) expression. In this study, we demonstrated that mitochondrial respiratory defects induced Cln-1 transcription via reactive oxygen species (ROS)-mediated heat shock factor 1 (HSF1) activation, which contributed to hepatoma invasiveness. We first confirmed the inverse relationship between mitochondrial defects and Cln-1 induction in SNU hepatoma cells and hepatocellular carcinoma tissues. We then examined five different respiratory complex inhibitors, and complex I inhibition by rotenone most effectively induced Cln-1 at the transcriptional level. Rotenone increased both mitochondrial and cytosolic ROS. In addition, rotenone-induced Cln-1 expression was attenuated by N-acetylcysteine, an antioxidant, and exogenous H2O2 treatment was enough to increase Cln-1 transcription, implying the involvement of ROS. Next we found that ROS-mediated HSF1 activation via hyperphosphorylation was the key event for Cln-1 transcription. Moreover, the Cln-1 promoter region (from -529 to +53) possesses several HSF1 binding elements, and this region showed increased promoter activity and HSF1 binding affinity in response to rotenone treatment. Finally, we demonstrated that the invasion activity of SNU449 cells, which harbor mitochondrial defects, was blocked by siRNA-mediated HSF1 knockdown. Taken together, these results indicate that mitochondrial respiratory defects enhance Cln-1-mediated hepatoma cell invasiveness via mitochondrial ROS-mediated HSF1 activation, presenting a potential role for HSF1 as a novel mitochondrial retrograde signal-responsive transcription factor to control hepatoma cell invasiveness.

Yang J, Zhang Y, Zhao S, et al.
Heat shock protein 70 induction by glutamine increases the α-synuclein degradation in SH-SY5Y neuroblastoma cells.
Mol Med Rep. 2015; 12(4):5524-30 [PubMed] Related Publications
Functional defects in heat shock proteins (HSPs), e.g. Hsp70, have been reported to have a key role in Parkinson's disease (PD). Overexpressed Hsp70 re‑folds aggregated α‑synuclein to generate the non‑toxic and non‑aggregated form. Thus, Hsp70 is a well‑defined therapeutic target, and Hsp70 promotion is an efficient strategy to prevent or even reverse the α‑synuclein‑induced toxicity in PD. The present study investigated the promotion of Hsp70 expression in SH‑SY5Y neuroblastoma cells by glutamine (Gln), which has recently been recognized to induce Hsp70 expression. Furthermore, the role of heat shock factor (HSF)‑1 in the Gln‑mediated upregulation of Hsp70 expression was investigated. In addition, the regulatory role of Gln in α‑synuclein degradation in α‑synuclein‑overexpressing SH‑SY5Y cells was determined. The results of the present study demonstrated that Gln treatment significantly upregulated Hsp70 expression at the mRNA as well as the protein level in a dose‑dependent and time‑dependent manner. Gln‑induced Hsp70 upregulation was found to be HSF‑1‑dependent, as HSF‑1 knockdown abrogated the Hsp70 upregulation by Gln in α‑synuclein‑overexpressing SH‑SY5Y cells. In conclusion, present study confirmed that Gln upregulates Hsp70 expression in SH‑SY5Y neuroblastoma cells in an HSF‑1‑dependent manner. The upregulation of Hsp70 by Gln increases the α‑synuclein degradation. Therefore, Gln may be a potential therapeutic agent to prevent α‑synuclein aggregation in PD.

Björk JK, Åkerfelt M, Joutsen J, et al.
Heat-shock factor 2 is a suppressor of prostate cancer invasion.
Oncogene. 2016; 35(14):1770-84 [PubMed] Free Access to Full Article Related Publications
Heat-shock factors (HSFs) are key transcriptional regulators in cell survival. Although HSF1 has been identified as a driver of carcinogenesis, HSF2 has not been explored in malignancies. Here, we report that HSF2 suppresses tumor invasion of prostate cancer (PrCa). In three-dimensional organotypic cultures and the in vivo xenograft chorioallantoic membrane model HSF2 knockdown perturbs organoid differentiation and promotes invasiveness. Gene expression profiling together with functional studies demonstrated that the molecular mechanism underlying the effect on tumor progression originates from HSF2 steering the switch between acinar morphogenesis and invasion. This is achieved by the regulation of genes connected to, for example, GTPase activity, cell adhesion, extracellular matrix and actin cytoskeleton dynamics. Importantly, low HSF2 expression correlates with high Gleason score, metastasis and poor survival of PrCa patients, highlighting the clinical relevance of our findings. Finally, the study was expanded beyond PrCa, revealing that the expression of HSF2 is decreased in a wide range of cancer types. This study provides the first evidence for HSF2 acting as a suppressor of invasion in human malignancies.

Jiang S, Tu K, Fu Q, et al.
Multifaceted roles of HSF1 in cancer.
Tumour Biol. 2015; 36(7):4923-31 [PubMed] Related Publications
Heat shock transcription factor 1 (HSF1) is the master regulator of the heat shock response. Accumulating evidence shows that HSF1 is overexpressed in a variety of human cancers, is associated with cancer aggressiveness, and could serve as an independent diagnostic or prognostic biomarker. In this review, we will provide an overview of the multifaceted roles of HSF1 in cancer, with a special focus on the four underlying molecular mechanisms involved. First, HSF1 regulates the expression of heat shock proteins (HSPs) including HSP90, HSP70, and HSP27. Second, HSF1 regulates cellular metabolism, including glycolysis and lipid metabolism. Third, HSF1 serves as a regulator of different signaling pathways, such as HuR-HIF-1, Slug, protein kinase C (PKC), nuclear factor-kappaB (NF-κB), PI3K-AKT-mTOR, and mitogen-activated protein kinase (MAPK) pathways. Finally, HSF1 regulates microRNAs (miRNAs) and long non-coding RNAs (lncRNAs). Overall, HSF1 plays many important roles in cancer via regulating cell proliferation, anti-apoptosis, epithelial-mesenchymal transition (EMT), migration, invasion, and metastasis and may be a potential therapeutic target for human cancers.

Mani J, Antonietti P, Rakel S, et al.
Knockdown of BAG3 sensitizes bladder cancer cells to treatment with the BH3 mimetic ABT-737.
World J Urol. 2016; 34(2):197-205 [PubMed] Related Publications
PURPOSE: BAG3 is overexpressed in several malignancies and mediates a non-canonical, selective form of (macro)autophagy. By stabilizing pro-survival Bcl-2 proteins in complex with HSP70, BAG3 can also exert an apoptosis-antagonizing function. ABT-737 is a high affinity Bcl-2 inhibitor that fails to target Mcl-1. This failure may confer resistance in various cancers.
METHODS: Urothelial cancer cells were treated with the BH3 mimetics ABT-737 and (-)-gossypol, a pan-Bcl-2 inhibitor which inhibits also Mcl-1. To clarify the importance of the core autophagy regulator ATG5 and BAG3 in ABT-737 treatment, cell lines carrying a stable lentiviral knockdown of ATG5 and BAG3 were created. The synergistic effect of ABT-737 and pharmaceutical inhibition of BAG3 with the HSF1 inhibitor KRIBB11 or sorafenib was also evaluated. Total cell death and apoptosis were quantified by FACS analysis of propidium iodide, annexin. Target protein analysis was conducted by Western blotting.
RESULTS: Knockdown of BAG3 significantly downregulated Mcl-1 protein levels and sensitized urothelial cancer cells to apoptotic cell death induced by ABT-737, while inhibition of bulk autophagy through depletion of ATG5 had no discernible effect on cell death. Similar to knockdown of BAG3, pharmacological targeting of the BAG3/Mcl-1 pathway with KRIBB11 was capable to sensitize both cell lines to treatment with ABT-737.
CONCLUSION: Our results show that BAG3, but not bulk autophagy has a major role in the response of bladder cancer cells to BH3 mimetics. They also suggest that BAG3 is a suitable target for combined therapies aimed at synergistically inducing apoptosis in bladder cancer.

Kuramitsu Y, Tanaka I, Wang Y, et al.
Inflammation-Related Tumor Progression in Murine Fibrosarcoma Exhibited Over-expression of Sex-determining Region Y-box 2 (Sox2) Compared to Parental Regressor Cells.
Anticancer Res. 2015; 35(6):3217-21 [PubMed] Related Publications
BACKGROUND/AIM: Tumor progression is one of the most serious issues to overcome cancer disease. As a model of inflammation-induced tumor progression, we used the regressive murine fibrosarcoma cell clone QR-32 and the progressive malignant clone QRsP-11, that was derived from QR-32. Heat shock protein beta-1 (Hspb1) is a molecular chaperone. Hspb1 plays roles in not only cell protection but also chemo-resistance, tumorigenicity and protection from apoptosis. In a recent study, we showed that Hspb1 was up-regulated in QRsP-11 compared to QR-32.
MATERIALS AND METHODS: We compared the expression levels of Hspb1, Hsf1 and Sox2 in QR-32 and QRsP-11 cells by means of western blotting.
RESULTS: Hsf1, a transcription factor for Hspb1 was not increased in QRsP-11. Sex determining region Y-box 2 (Sox2) is a transcription factor, reported to interact with Hspb1. Sox2 was up-regulated in QRsP-11 compared to QR-32.
CONCLUSION: These results suggest that Sox2-Hspb1 signaling is a possible pathway responsible to tumor progression of QRsP-11.

Luan Q, Jin L, Jiang CC, et al.
RIPK1 regulates survival of human melanoma cells upon endoplasmic reticulum stress through autophagy.
Autophagy. 2015; 11(7):975-94 [PubMed] Free Access to Full Article Related Publications
Although RIPK1 (receptor [TNFRSF]-interacting protein kinase 1) is emerging as a critical determinant of cell fate in response to cellular stress resulting from activation of death receptors and DNA damage, its potential role in cell response to endoplasmic reticulum (ER) stress remains undefined. Here we report that RIPK1 functions as an important prosurvival mechanism in melanoma cells undergoing pharmacological ER stress induced by tunicamycin (TM) or thapsigargin (TG) through activation of autophagy. While treatment with TM or TG upregulated RIPK1 and triggered autophagy in melanoma cells, knockdown of RIPK1 inhibited autophagy and rendered the cells sensitive to killing by TM or TG, recapitulating the effect of inhibition of autophagy. Consistently, overexpression of RIPK1 enhanced induction of autophagy and conferred resistance of melanoma cells to TM- or TG-induced cell death. Activation of MAPK8/JNK1 or MAPK9/JNK2, which phosphorylated BCL2L11/BIM leading to its dissociation from BECN1/Beclin 1, was involved in TM- or TG-induced, RIPK1-mediated activation of autophagy; whereas, activation of the transcription factor HSF1 (heat shock factor protein 1) downstream of the ERN1/IRE1-XBP1 axis of the unfolded protein response was responsible for the increase in RIPK1 in melanoma cells undergoing pharmacological ER stress. Collectively, these results identify upregulation of RIPK1 as an important resistance mechanism of melanoma cells to TM- or TG-induced ER stress by protecting against cell death through activation of autophagy, and suggest that targeting the autophagy-activating mechanism of RIPK1 may be a useful strategy to enhance sensitivity of melanoma cells to therapeutic agents that induce ER stress.

Ma W, Zhang Y, Mu H, et al.
Glucose regulates heat shock factor 1 transcription activity via mTOR pathway in HCC cell lines.
Cell Biol Int. 2015; 39(11):1217-24 [PubMed] Related Publications
HSF1-mediated heat shock response is activated in most tumors and plays important roles in regulating tumor homeostasis. However, the signals underlying HSF1 activation is still not completely understood. In this paper, we find that glucose, the dominant tumor energy supplement, participates in regulating HSF1's activation in HCC cell lines. The immunoblotting results indicate that the phosphorylation of HSF1/S326, a hallmark of HSF1 activation, varies between the HCC cell lines (e.g., SMMC7721, HapG2, plc/prf5, and Chang-liver). Glucose, but not 2D-glucose, can induce the phosphorylation of HSF1 at S326 and upregulate the expression of HSF1's downstream alpha B-crystallin and Hsp70 as well as the none-heat shock proteins CSK2 and RBM23 in two tested hepatocellular carcinoma cell lines (prl/prf5 and SMMC7721). Rapamycin, an inhibitor of mTOR, can suppress the glucose-induced phosphorylation of HSF1/S326 and the expression of alpha B-crystallin. Knockdown of HSF1 with shRNA enhances the glucose-depletion-mediated inhibition of plc/prf5 cell proliferation. Our data reveal that HSF1 can be activated by glucose-mTOR pathway, providing an alternative pathway for targeting HSF1 in tumor therapy.

Bustany S, Cahu J, Descamps G, et al.
Heat shock factor 1 is a potent therapeutic target for enhancing the efficacy of treatments for multiple myeloma with adverse prognosis.
J Hematol Oncol. 2015; 8:40 [PubMed] Free Access to Full Article Related Publications
Deregulated expression of heat shock proteins (HSPs) encoding genes is frequent in multiple myeloma. HSPs, which are molecular chaperones involved in protein homeostasis pathways, have emerged recently as promising therapeutic targets. Using human myeloma cell lines and primary myeloma cells belonging to various molecular groups, we tested the efficacy of HSP90, HSP70, and heat shock factor 1 (HSF1) inhibitors alone or associated with current antimyeloma drugs. We report here that KNK-437 (an inhibitor of HSF1) and bortezomib have additive effects on apoptosis induction in cells belonging to groups with bad prognosis.

Schilling D, Kühnel A, Tetzlaff F, et al.
NZ28-induced inhibition of HSF1, SP1 and NF-κB triggers the loss of the natural killer cell-activating ligands MICA/B on human tumor cells.
Cancer Immunol Immunother. 2015; 64(5):599-608 [PubMed] Free Access to Full Article Related Publications
The activity of natural killer (NK) cells is regulated by activating and inhibiting receptors, whereby the C-type lectin natural killer group 2D (NKG2D) receptor serves as the major activating receptor on NK cells which recognizes major histocompatibility class I chain-related proteins A and B (MICA/B). The MICA/B expression has been described to be regulated by the transcription factor heat shock factor 1 (HSF1). Inhibition of heat shock protein 90 (Hsp90) is known to induce the heat shock response via activation of HSF1 which is associated with tumor development, metastasis and therapy resistance and also with an increased susceptibility to NK cell-mediated lysis. Therefore, we compared the effects of Hsp90 inhibitor NVP-AUY922, HSF1 inhibitor NZ28 and HSF1 knockdown on the sensitivity of lung (H1339) and breast (MDA-MB-231, T47D) cancer cells to NK cell-mediated cytotoxicity and the expression of the NKG2D ligands MICA/B. Although NVP-AUY922 activates HSF1, neither the MICA/B surface density on tumor cells nor their susceptibility to NK cell-mediated lysis was affected. A single knockdown of HSF1 by shRNA decreased the surface expression of MICB but not that of MICA, and thereby, the NK cell-mediated lysis was only partially blocked. In contrast, NZ28 completely blocked the MICA/B membrane expression on tumor cells and thereby strongly inhibited the NK cell-mediated cytotoxicity. This effect might be explained by a simultaneous inhibition of the transcription factors HSF1, Sp1 and NF-κB by NZ28. These findings suggest that new anticancer therapeutics should be investigated with respect to their effects on the innate immune system.

Kim JA, Lee S, Kim DE, et al.
Fisetin, a dietary flavonoid, induces apoptosis of cancer cells by inhibiting HSF1 activity through blocking its binding to the hsp70 promoter.
Carcinogenesis. 2015; 36(6):696-706 [PubMed] Related Publications
Heat shock factor 1 (HSF1) is a transcription factor for heat shock proteins (HSPs) expression that enhances the survival of cancer cells exposed to various stresses. HSF1 knockout suppresses carcinogen-induced cancer induction in mice. Therefore, HSF1 is a promising therapeutic and chemopreventive target. We performed cell-based screening with a natural compound collection and identified fisetin, a dietary flavonoid, as a HSF1 inhibitor. Fisetin abolished heat shock-induced luciferase activity with an IC50 of 14 μM in HCT-116 cancer cells. The treatment of HCT-116 with fisetin inhibited proliferation with a GI50 of 23 μM. When the cells were exposed to heat shock in the presence of fisetin, the induction of HSF1 target proteins, such as HSP70, HSP27 and BAG3 (Bcl-2-associated athanogene domain 3), were inhibited. HSP70/BAG3 complexes protect cancer cells from apoptosis by stabilizing anti-apoptotic Bcl-2 family proteins. The downregulation of HSP70/BAG3 by fisetin significantly reduced the amounts of Bcl-2, Bcl-xL and Mcl-1 proteins, subsequently inducing apoptotic cell death. Chromatin immunoprecipitation assays showed that fisetin inhibited HSF1 activity by blocking the binding of HSF1 to the hsp70 promoter. Intraperitoneal treatment of nude mice with fisetin at 30mg/kg resulted in a 35.7% (P < 0.001) inhibition of tumor growth.

Home T, Jensen RA, Rao R
Heat shock factor 1 in protein homeostasis and oncogenic signal integration.
Cancer Res. 2015; 75(6):907-12 [PubMed] Related Publications
Heat shock factor 1 (HSF1) is a stress-inducible transcription factor and has been described as a multi-faceted modulator of tumorigenesis. Heat shock, accumulation of misfolded proteins, or malignant transformation promotes the activation and nuclear translocation of HSF1, where it binds to the promoters of heat shock proteins and an array of nonheat shock-regulated proteins to upregulate their transcription. These stress-responsive and tumor-promoting genes in turn alter the ability of tumor cells to respond to a variety of stresses and enable them to thrive in less than favorable growth conditions. Although a direct role for HSF1 in promoting mRNA transcription of tumor-promoting genes has been suggested, it appears that this property is context- and cell-type dependent. Furthermore, recent studies have demonstrated a direct involvement of mTOR signaling in regulating HSF1-mediated transcription, thus establishing a direct link between protein translation and HSF1 activity. Interestingly, there is a growing understanding of the signaling pathways that are modulated by HSF1 in a variety of tumor types and the co-option of these survival pathways by HSF1 to promote tumorigenesis. This review will focus on the role of HSF1 in protein homeostasis and HSF1-mediated oncogenic signaling pathways that together promote tumorigenesis.

Kourtis N, Moubarak RS, Aranda-Orgilles B, et al.
FBXW7 modulates cellular stress response and metastatic potential through ​HSF1 post-translational modification.
Nat Cell Biol. 2015; 17(3):322-32 [PubMed] Free Access to Full Article Related Publications
​Heat-shock factor 1 (​HSF1) orchestrates the heat-shock response in eukaryotes. Although this pathway has evolved to help cells adapt in the presence of challenging conditions, it is co-opted in cancer to support malignancy. However, the mechanisms that regulate ​HSF1 and thus cellular stress response are poorly understood. Here we show that the ubiquitin ligase ​FBXW7α interacts with ​HSF1 through a conserved motif phosphorylated by ​GSK3β and ​ERK1. ​FBXW7α ubiquitylates ​HSF1 and loss of ​FBXW7α results in impaired degradation of nuclear ​HSF1 and defective heat-shock response attenuation. ​FBXW7α is either mutated or transcriptionally downregulated in melanoma and ​HSF1 nuclear stabilization correlates with increased metastatic potential and disease progression. ​FBXW7α deficiency and subsequent ​HSF1 accumulation activates an invasion-supportive transcriptional program and enhances the metastatic potential of human melanoma cells. These findings identify a post-translational mechanism of regulation of the ​HSF1 transcriptional program both in the presence of exogenous stress and in cancer.

Donnelly N, Storchová Z
Causes and consequences of protein folding stress in aneuploid cells.
Cell Cycle. 2015; 14(4):495-501 [PubMed] Free Access to Full Article Related Publications
Imbalanced chromosomal content, or aneuploidy, strongly affects the physiology of eukaryotic cells. The consequences of these effects are frequently detrimental, in particular in Metazoans. In humans, aneuploidy has been causatively linked to pathological conditions such as spontaneous abortions, trisomy syndromes and cancer. However, only in recent years have we witnessed an unraveling of the complex phenotypes that are caused by aneuploidy. Importantly, it has become apparent that aneuploidy evokes global and uniform changes that cannot be explained by the altered expression of the specific genes located on aneuploid chromosomes. Recent discoveries show that aneuploidy negatively affects protein folding; in particular, the functions of the molecular chaperone Heat Shock Protein 90 (HSP90) and the upstream regulator of heat shock-induced transcription, Heat Shock Factor 1 (HSF1), are impaired. Here we discuss the possible causes and consequences of this impairment and propose that the protein folding stress instigated by aneuploidy may be a common feature of conditions as variable as cancer and trisomy syndromes.

Li Y, Xu D, Bao C, et al.
MicroRNA-135b, a HSF1 target, promotes tumor invasion and metastasis by regulating RECK and EVI5 in hepatocellular carcinoma.
Oncotarget. 2015; 6(4):2421-33 [PubMed] Free Access to Full Article Related Publications
MicroRNAs (miRNAs) often localize to chromosomal fragile sites and are associated with cancer. In this study, we screened for the aberrant and functional miRNAs in the regions of copy number alterations (CNAs) in hepatocellular carcinoma (HCC), and found that miR-135b was frequently amplified and upregulated in HCC tissues. The expression level of miR-135b was inversely correlated with the occurrence of tumor capsules. In addition, miR-135b promoted HCC cell migration and invasion in vitro and metastasis in vivo. The reversion-inducing-cysteine-rich protein with kazal motifs (RECK) and ecotropic viral integration site 5 (EVI5) were identified as the direct and functional targets of miR-135b in HCC. Furthermore, we observed that heat shock transcription factor 1 (HSF1) directly activated miR-135b expression, consequently enhancing HCC cell motility and invasiveness. The newly identified HSF1/miR-135b/RECK&EVI5 axis provides novel insight into the mechanisms of HCC metastasis, which may facilitate the development of new therapeutics against HCC.

Toma-Jonik A, Widlak W, Korfanty J, et al.
Active heat shock transcription factor 1 supports migration of the melanoma cells via vinculin down-regulation.
Cell Signal. 2015; 27(2):394-401 [PubMed] Related Publications
Heat shock transcription factor 1 (HSF1), the major regulator of stress response, is frequently activated in cancer and has an apparent role in malignant transformation. Here we analyzed the influence of the over-expression of a constitutively active transcriptionally-competent HSF1 mutant form on phenotypes of mouse and human melanoma cells. We observed that the expression of active HSF1 supported anchorage-independent growth in vitro, and metastatic spread in the animal model in vivo, although the proliferation rate of cancer cells was not affected. Furthermore, active HSF1 enhanced cell motility, reduced the adherence of cells to a fibronectin-coated surface, and affected the actin cytoskeleton. We found that although the expression of active HSF1 did not affect levels of epithelial-to-mesenchymal transition markers, it caused transcriptional down-regulation of vinculin, protein involved in cell motility, and adherence. Functional HSF1-binding sites were found in mouse and human Vcl/VCL genes, indicating a direct role of HSF1 in the regulation of this gene. An apparent association between HSF1-induced down-regulation of vinculin, increased motility, and a reduced adherence of cells suggests a possible mechanism of HSF1-mediated enhancement of the metastatic potential of cancer cells.

Benderska N, Ivanovska J, Rau TT, et al.
DAPK-HSF1 interaction as a positive-feedback mechanism stimulating TNF-induced apoptosis in colorectal cancer cells.
J Cell Sci. 2014; 127(Pt 24):5273-87 [PubMed] Related Publications
Death-associated protein kinase (DAPK) is a serine-threonine kinase with tumor suppressor function. Previously, we demonstrated that tumor necrosis factor (TNF) induced DAPK-mediated apoptosis in colorectal cancer. However, the protein-protein interaction network associated with TNF-DAPK signaling still remains unclear. We identified HSF1 as a new DAPK phosphorylation target in response to low concentrations of TNF and verified a physical interaction between DAPK and HSF1 both in vitro and in vivo. We show that HSF1 binds to the DAPK promoter. Transient overexpression of HSF1 protein led to an increase in DAPK mRNA level and consequently to an increase in the amount of apoptosis. By contrast, treatment with a DAPK-specific inhibitor as well as DAPK knockdown abolished the phosphorylation of HSF1 at Ser230 (pHSF1(Ser230)). Furthermore, translational studies demonstrated a positive correlation between DAPK and pHSF1(Ser230) protein expression in human colorectal carcinoma tissues. Taken together, our data define a novel link between DAPK and HSF1 and highlight a positive-feedback loop in DAPK regulation under mild inflammatory stress conditions in colorectal tumors. For the first time, we show that under TNF the pro-survival HSF1 protein can be redirected to a pro-apoptotic program.

Aricò A, Ferraresso S, Bresolin S, et al.
Array-based comparative genomic hybridization analysis reveals chromosomal copy number aberrations associated with clinical outcome in canine diffuse large B-cell lymphoma.
PLoS One. 2014; 9(11):e111817 [PubMed] Free Access to Full Article Related Publications
Canine Diffuse Large B-cell Lymphoma (cDLBCL) is an aggressive cancer with variable clinical response. Despite recent attempts by gene expression profiling to identify the dog as a potential animal model for human DLBCL, this tumor remains biologically heterogeneous with no prognostic biomarkers to predict prognosis. The aim of this work was to identify copy number aberrations (CNAs) by high-resolution array comparative genomic hybridization (aCGH) in 12 dogs with newly diagnosed DLBCL. In a subset of these dogs, the genetic profiles at the end of therapy and at relapse were also assessed. In primary DLBCLs, 90 different genomic imbalances were counted, consisting of 46 gains and 44 losses. Two gains in chr13 were significantly correlated with clinical stage. In addition, specific regions of gains and losses were significantly associated to duration of remission. In primary DLBCLs, individual variability was found, however 14 recurrent CNAs (>30%) were identified. Losses involving IGK, IGL and IGH were always found, and gains along the length of chr13 and chr31 were often observed (>41%). In these segments, MYC, LDHB, HSF1, KIT and PDGFRα are annotated. At the end of therapy, dogs in remission showed four new CNAs, whereas three new CNAs were observed in dogs at relapse compared with the previous profiles. One ex novo CNA, involving TCR, was present in dogs in remission after therapy, possibly induced by the autologous vaccine. Overall, aCGH identified small CNAs associated with outcome, which, along with future expression studies, may reveal target genes relevant to cDLBCL.

Das S, Bhattacharyya NP
Heat shock factor 1 regulates hsa-miR-432 expression in human cervical cancer cell line.
Biochem Biophys Res Commun. 2014; 453(3):461-6 [PubMed] Related Publications
Heat shock response pathway is a conserved defense mechanism of mammalian cells to maintain protein homeostasis against proteotoxic environmental conditions. This is characterized by robust synthesis of molecular chaperones mostly by stress-induced activation of heat shock factor 1 (HSF1). MicroRNAs (miRNAs) are a family of small non-coding RNAs that negatively regulate expression of protein-coding genes. Here we report altered expression of a set of miRNAs by thermal stress in HeLa cells. We also show that HSF1 regulates hsa-miR-432 expression in heat shock-dependent manner through its cognate binding site present in hsa-miR-432 upstream sequence. Our report uncovers a novel function of HSF1 and indicates involvement of miRNAs in HSF1-mediated protection of cellular proteome.

Li S, Ma W, Fei T, et al.
Upregulation of heat shock factor 1 transcription activity is associated with hepatocellular carcinoma progression.
Mol Med Rep. 2014; 10(5):2313-21 [PubMed] Free Access to Full Article Related Publications
Heat shock factor 1 (HSF1) is associated with tissue‑specific tumorigenesis in a number of mouse models, and has been used a as prognostic marker of cancer types, including breast and prostatic cancer. However, its role in human hepatocellular carcinoma (HCC) is not well understood. Using immunoblotting and immunohistochemical staining, it was identified that HSF1 and its serine (S) 326 phosphorylation, a biomarker of HSF1 activation, are significantly upregulated in human HCC tissues and HCC cell lines compared with their normal counterparts. Cohort analyses indicated that upregulation of the expression of HSF1 and its phospho‑S326 is significantly correlated with HCC progression, invasion and patient survival prognosis (P<0.001); however, not in the presence of a hepatitis B virus infection and the expression of alpha-fetoprotein and carcinoembryonic antigen. Knockdown of HSF1 with shRNA induced the protein expression of tumor suppressor retinoblastoma protein, resulting in attenuated plc/prf5 cell growth and colony formation in vitro. Taken together, these data markedly support that HSF1 is a potential prognostic marker and therapeutic target for the treatment of HCC.

Nakamura Y, Fujimoto M, Fukushima S, et al.
Heat shock factor 1 is required for migration and invasion of human melanoma in vitro and in vivo.
Cancer Lett. 2014; 354(2):329-35 [PubMed] Related Publications
Heat shock factor 1 (HSF1) is a major transactivator of the heat shock response. Recent studies have demonstrated that HSF1 is involved in tumor initiation, maintenance, and progression by regulating the expression of heat shock proteins (HSPs) and other molecular targets. Furthermore, HSF1 was identified as a potent proinvasion oncogene in human melanomas. However, the biological functions of HSF1 in human melanoma remain poorly understood. To determine the functional role of HSF1 in melanoma, we used short hairpin RNA (shRNA) to silence HSF1 in human melanoma cell lines and investigated its effect on cell migration and invasive ability in vitro. We found that HSF1 knockdown led to a marked reduction in migration and invasive ability, and these functions were restored by overexpression of wild-type HSF1. To confirm the in vitro results, we performed subcutaneous xenograft experiments in athymic nude mice. We found that HSF1 was required for melanoma invasion and metastasis, as well as tumorigenic potential in vivo. Overall, these results show that HSF1 is indispensable for melanoma progression and metastasis, and suggests that HSF1 could be a promising therapeutic target for melanoma.

Chou SD, Murshid A, Eguchi T, et al.
HSF1 regulation of β-catenin in mammary cancer cells through control of HuR/elavL1 expression.
Oncogene. 2015; 34(17):2178-88 [PubMed] Free Access to Full Article Related Publications
There is now compelling evidence to indicate a place for heat shock factor 1 (HSF1) in mammary carcinogenesis, tumour progression and metastasis. Here we have investigated a role for HSF1 in regulating the expression of the stem cell renewal factor β-catenin in immortalized human mammary epithelial and carcinoma cells. We found HSF1 to be involved in regulating the translation of β-catenin, by investigating effects of gain and loss of HSF1 on this protein. Interestingly, although HSF1 is a potent transcription factor, it was not directly involved in regulating levels of β-catenin mRNA. Instead, our data suggest a complex role in translational regulation. HSF1 was shown to regulate levels of the RNA-binding protein HuR that controlled β-catenin translation. An extra complexity was added to this scenario when it was shown that the long non-coding RNA molecule lincRNA-p21, known to be involved in β-catenin mRNA (CTNNB1) translational regulation, was controlled by HSF1 repression. We have shown previously that HSF1 was positively regulated through phosphorylation by mammalian target of rapamycin (mTOR) kinase on a key residue, serine 326, essential for transcriptional activity. In this study, we found that mTOR knockdown not only decreased HSF1-S326 phosphorylation in mammary cells, but also decreased β-catenin expression through a mechanism requiring HuR. Our data point to a complex role for HSF1 in the regulation of HuR and β-catenin expression that may be significant in mammary carcinogenesis.

Musiani D, Konda JD, Pavan S, et al.
Heat-shock protein 27 (HSP27, HSPB1) is up-regulated by MET kinase inhibitors and confers resistance to MET-targeted therapy.
FASEB J. 2014; 28(9):4055-67 [PubMed] Related Publications
The tyrosine kinase encoded by the MET oncogene is activated by gene mutation or amplification in tumors, which in most instances maintain addiction, i.e., dependency, to MET activation. This makes MET an attractive candidate for targeted therapies. Here we show that, in 3/3 MET-addicted human gastric cancer cell lines, MET kinase inhibition resulted in a 3- to 4-fold increased expression of the antiapoptotic small heat-shock protein of 27 kDa (HSP27, HSPB1). HSP27 increase depended on the inhibition of the MEK/ERK pathway and on heat-shock factor 1 (HSF1) and hypoxia-inducible factor-1α (HIF-1α) regulation. Importantly, HSP27-silenced MET-addicted cells underwent 2- and 3-fold more apoptosis following MET inhibition in vitro and in vivo, respectively. Likewise, in human cancer cells susceptible to epidermal growth factor receptor (EGFR) inhibition, EGFR inhibitors induced HSP27 expression and were strengthened by HSP27 suppression. In control cell lines that were not affected by drugs targeting MET or EGFR, these drugs did not induce HSP27 increase. Therefore, in cancer therapies targeting the MET pathway, the induction of HSP27 might limit the efficacy of anti-MET agents. As HSP27 increase also impairs the effectiveness of EGFR inhibitors and is known to protect cells from chemotherapeutics, the induction of HSP27 by targeted agents might strongly affect the success of combination treatments.

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