Elevated levels of HSF1 indicate a poor prognosis in breast cancer

Inhibition of Heat Shock Factor 1 Signaling Decreases Hepatoblastoma Growth via Induction of Apoptosis

Although rare compared with adult liver cancers, hepatoblastoma (HB) is the most common pediatric liver malignancy, and its incidence is increasing. Currently, the treatment includes surgical resection with or without chemotherapy, and in severe cases, liver transplantation in children. The effort to develop more targeted, HB-specific therapies has been stymied by the lack of fundamental knowledge about HB biology. Heat shock factor 1 (HSF1), a transcription factor, is a canonical inducer of heat shock proteins, which act as chaperone proteins to prevent or undo protein misfolding. Recent work has shown a role for HSF1 in cancer beyond the canonical heat shock response. The current study found increased HSF1 signaling in HB versus normal liver. It showed that less differentiated, more embryonic tumors had higher levels of HSF1 than more differentiated, more fetal-appearing tumors. Most strikingly, HSF1 expression levels correlated with mortality. This study used a mouse model of HB to test the effect of inhibiting HSF1 early in tumor development on cancer growth. HSF1 inhibition resulted in fewer and smaller tumors, suggesting HSF1 is needed for aggressive tumor growth. Moreover, HSF1 inhibition also increased apoptosis in tumor foci. These data suggest that HSF1 may be a viable pharmacologic target for HB treatment.

Receptor-Interacting Protein 140 Enhanced Temozolomide-Induced Cellular Apoptosis Through Regulation of E2F1 in Human Glioma Cell Lines

Glioblastoma (GBM), a grade IV glioma, is responsible for the highest years of potential life lost among cancers. The poor prognosis is attributable to its high recurrence rate, caused in part by the development of resistance to chemotherapy. Receptor-interacting protein 140 (RIP140) is a very versatile coregulator of nuclear receptors and transcription factors. Although many of the pathways regulated by RIP140 contribute significantly to cancer progression, the function of RIP140 in GBM remains to be determined. In this study, we found that higher RIP140 expression was associated with prolonged survival in patients with newly diagnosed GBM. Intracellular RIP140 levels were increased after E2F1 activation following temozolomide (TMZ) treatment, which in turn modulated the expression of E2F1-targeted apoptosis-related genes. Overexpression of RIP140 reduced glioma cell proliferation and migration, induced cellular apoptosis, and sensitized GBM cells to TMZ. Conversely, knockdown of RIP140 increased TMZ resistance. Taken together, our results suggest that RIP140 prolongs the survival of patients with GBM both by inhibiting tumor cell proliferation and migration and by increasing cellular sensitivity to chemotherapy. This study helps improve our understanding of glioma recurrence and may facilitate the development of more effective treatments.

Proteomics analysis of proteins interacting with heat shock factor 1 in squamous cell carcinoma of the cervix

Protein interactions are crucial for maintaining homeostasis. Heat shock factor 1 (HSF1), a transcription factor that interacts with various proteins, is highly expressed in squamous cell carcinoma (SCC) of the cervix. The aim of the present study was to investigate the protein interaction profile of HSF1 in cervical SCC. Proteins interacting with HSF1 in SCC tissue and non-cancerous control (Ctrl) tissue were obtained by immunoprecipitation, separated by SDS-PAGE, identified by matrix-assisted laser desorption/ionization-time-of-flight mass spectrometry and analyzed using bioinformatics methods. A total of 220 and 241 proteins were identified by mass spectrometry in the tissues of Ctrl and SCC samples, respectively, among which 172 were detected exclusively in SCC (Pro-S), 151 exclusively in Ctrl (Pro-C) and 69 in both groups (Pro-B). The protein interaction profiles were different in each group; the STRING database identified three proteins that interacted with HSF1 directly, including insulin-like growth factor 1 receptor and small nuclear RNA-activating protein complex subunit 4 in Pro-C and small ubiquitin-related modifier 1 in Pro-S. Functional enrichment analysis of Gene Ontology revealed that the top terms were alternative splicing in Pro-S and polymorphism in Pro-C. In Pro-S, more categories were related to protein modification, such as phosphorylation, ubiquitination and acetylation. Therefore, HSF1 may influence the occurrence and development of cervical SCC by interacting with specific proteins.

FAM3C-YY1 axis is essential for TGFβ-promoted proliferation and migration of human breast cancer MDA-MB-231 cells via the activation of HSF1

Family with sequence similarity three member C (FAM3C) (interleukin‐like EMT inducer [ILEI]), heat shock factor 1 (HSF1) and Ying‐Yang 1 (YY1) have been independently reported to be involved in the pathogenesis of various cancers. However, whether they are coordinated to trigger the development of cancer remains unknown. This study determined the role and mechanism of YY1 and HSF1 in FAM3C‐induced proliferation and migration of breast cancer cells. In human MDA‐MB‐231 breast cancer cell line, transforming growth factor‐β (TGFβ) up‐regulated FAM3C, HSF1 and YY1 expressions. FAM3C overexpression promoted the proliferation and migration of MDA‐MB‐231 cells with YY1 and HSF1 up‐regulation, whereas FAM3C silencing exerted the opposite effects. FAM3C inhibition repressed TGFβ‐induced HSF1 activation, and proliferation and migration of breast cancer cells. YY1 was shown to directly activate HSF1 transcription to promote the proliferation and migration of breast cancer cells. YY1 silencing blunted FAM3C‐ and TGFβ‐triggered activation of HSF1‐Akt‐Cyclin D1 pathway, and proliferation and migration of breast cancer cells. Inhibition of HSF1 blocked TGFβ‐, FAM3C‐ and YY1‐induced proliferation and migration of breast cancer cells. YY1 and HSF1 had little effect on FAM3C expression. Similarly, inhibition of HSF1 also blunted FAM3C‐ and TGFβ‐promoted proliferation and migration of human breast cancer BT‐549 cells. In human breast cancer tissues, FAM3C, YY1 and HSF1 protein expressions were increased. In conclusion, FAM3C activated YY1‐HSF1 signalling axis to promote the proliferation and migration of breast cancer cells. Furthermore, novel FAM3C‐YY1‐HSF1 pathway plays an important role in TGFβ‐triggered proliferation and migration of human breast cancer MDA‐MB‐231 cells.

Inhibition of Heat Shock Factor 1 Enhances Repressive Molecular Mechanisms on the POMC Promoter

BACKGROUND

Cushing's disease (CD) is caused by adrenocorticotropic hormone (ACTH)-secreting pituitary tumours. They express high levels of heat shock protein 90 and heat shock factor 1 (HSF1) in comparison to the normal tissue counterpart, indicating activated cellular stress.

AIMS

Our objectives were: (1) to correlate HSF1 expression with clinical features and hormonal/radiological findings of CD, and (2) to investigate the effects of HSF1 inhibition as a target for CD treatment.

PATIENTS/METHODS

We examined the expression of total and pSer326HSF1 (marker for its transcriptional activation) by Western blot on eight human CD tumours and compared to the HSF1 status of normal pituitary. We screened a cohort of 45 patients with CD for HSF1 by immunohistochemistry and correlated the HSF1 immunoreactivity score with the available clinical data. We evaluated the effects of HSF1 silencing with RNA interference and the HSF1 inhibitor KRIBB11 in AtT-20 cells and four primary cultures of human corticotroph tumours.

RESULTS

We show that HSF1 protein is highly expressed and transcriptionally active in CD tumours in comparison to normal pituitary. The immunoreactivity score for HSF1 did not correlate with the typical clinical features of the disease. HSF1 inhibition reduced proopiomelanocortin (Pomc) transcription in AtT-20 cells. The HSF1 inhibitor KRIBB11 suppressed ACTH synthesis from 75% of human CD tumours in primary cell culture. This inhibitory action on Pomc transcription was mediated by increased glucocorticoid receptor and suppressed Nurr77/Nurr1 and AP-1 transcriptional activities.

CONCLUSIONS

These data show that HSF1 regulates POMC transcription. Pharmacological targeting of HSF1 may be a promising treatment option for the control of excess ACTH secretion in CD.

Phenethyl Isothiocyanate, a Dual Activator of Transcription Factors NRF2 and HSF1

Cruciferous vegetables are rich sources of glucosinolates which are the biogenic precursor molecules of isothiocyanates (ITCs). The relationship between the consumption of cruciferous vegetables and chemoprotection has been widely documented in epidemiological studies. Phenethyl isothiocyanate (PEITC) occurs as its glucosinolate precursor gluconasturtiin in the cruciferous vegetable watercress (Nasturtium officinale). PEITC has multiple biological effects, including activation of cytoprotective pathways, such as those mediated by the transcription factor nuclear factor erythroid 2 p45-related factor 2 (NRF2) and the transcription factor heat shock factor 1 (HSF1), and can cause changes in the epigenome. However, at high concentrations, PEITC leads to accumulation of reactive oxygen species and cytoskeletal changes, resulting in cytotoxicity. Underlying these activities is the sulfhydryl reactivity of PEITC with cysteine residues in its protein targets. This chemical reactivity highlights the critical importance of the dose of PEITC for achieving on-target selectivity, which should be carefully considered in the design of future clinical trials.

Discovering a Reliable Heat-Shock Factor-1 Inhibitor to Treat Human Cancers: Potential Opportunity for Phytochemists

Heat-shock factor-1 (HSF-1) is an important transcription factor that regulates pathogenesis of many human diseases through its extensive transcriptional regulation. Especially, it shows pleiotropic effects in human cancer, and hence it has recently received increased attention of cancer researchers. After myriad investigations on HSF-1, the field has advanced to the phase where there is consensus that finding a potent and selective pharmacological inhibitor for this transcription factor will be a major break-through in the treatment of various human cancers. Presently, all reported inhibitors have their limitations, made evident at different stages of clinical trials. This brief account summarizes the advances with tested natural products as HSF-1 inhibitors and highlights the necessity of phytochemistry in this endeavor of discovering a potent pharmacological HSF-1 inhibitor.

Higher heat shock factor 1 expression in tumor stroma predicts poor prognosis in esophageal squamous cell carcinoma patients

Background

Heat shock factor 1 (HSF1) is a powerful, multifaceted modifier of carcinogenesis. However, the clinical significance and biologic function of HSF1 in esophageal squamous cell carcinoma (ESCC) remain unknown.

Methods

HSF1 was detected in ESCC cell lines, fibroblast cell lines and ESCC xenograft tumors and human ESCC tissues by real-time RT-PCR and western blotting. HSF1 protein expression was analyzed by immunochemistry in 134 ESCC patients followed by correlation with clinicopathological parameters.

Results

HSF1 expression is weak in fibroblast cell 3T3 and moderate in ESCC cell Eca109, but increasing expression of HSF1 was observed in both of 3T3 and Eca109 cells when they interplayed with each other. In Eca109 xenograft tumors, both tumor cells and stromal fibroblasts showed stronger expression of HSF1. In ESCC patients, the HSF1 expression in tumor or in stromal cells was significantly associated with tumor stage, lymph node metastasis and clinical stage. Multivariate analysis demonstrated a significant negative correlation between disease-free survival (DFS), overall survival (OS) and the HSF1 expression in stromal cells (P < 0.05) but not in tumor cells. Additionally, the expression of HSF1 in tumor cells or stromal cells was an independent factor for DFS (P = 0.032 or P = 0.012) and OS (P = 0.017 or P = 0.013) in metastatic ESCC patients but not for locoregional ESCC. ESCC patients with low HSF1 in both tumor cells and stromal cells had the longest survivals (P < 0.001).

Conclusions

The interaction of tumor cells and stromal fibroblasts increases the expression of HSF1 reciprocally in tumor microenvironment. The HSF1 expression in stromal cells was significantly associated with poor prognosis of ESCC.

Defective heat shock factor 1 inhibits the growth of fibrosarcoma derived from simian virus 40/T antigen‑transformed MEF cells

Heat shock factor 1 (Hsf1) serves an important role in regulating the proliferation of human tumor cell lines in vitro and tissue specific tumorigenesis in certain mouse models. However, its role in viral‑oncogenesis remains to be fully elucidated. In the current study, the role of Hsf1 in fibroblastoma derived from simian virus 40/T antigen (SV40/TAG)‑transformed mouse embryonic fibroblast (MEF) cell lines was investigated. Knockout of Hsf1 inhibited MEF cell proliferation in vitro and fibroblastoma growth and metastasis to the lungs in vivo in nude mice. Knockout of Hsf1 increased the protein expression levels of p53 and phosphorylated retinoblastoma protein (pRb), however reduced the expression of heat shock protein 25 (Hsp25) in addition to the expression of the angiogenesis markers vascular endothelial growth factor, cluster of differentiation 34 and factor VIII related antigen. Furthermore, immunoprecipitation indicated that knockout of Hsf1 inhibited the association between SV40/TAG and p53 or pRb. These data suggest that Hsf1 is involved in the regulation of SV40/TAG‑derived fibroblastoma growth and metastasis by modulating the association between SV40/TAG and tumor suppressor p53 and pRb. The current study provides further evidence that Hsf1 may be a novel therapeutic target in the treatment of cancer.