Heat shock transcription factor Hsf1 is involved in tumor progression via regulation of hypoxia-inducible factor 1 and RNA-binding protein HuR

The human testis-enriched HSPA2 interacts with HIF-1α in epidermal keratinocytes, yet HIF-1α stability and HIF-1-dependent gene expression rely on the HSPA (HSP70) activity

The Hypoxia-Inducible Factor 1 (HIF-1) is essential for cellular adaptation to reduced oxygen levels. It also facilitates the maintenance and re-establishment of skin homeostasis. Among others, it is involved in regulating keratinocyte differentiation. The stability of the oxygen-liable HIF-1α subunit is regulated by various non-canonical oxygen-independent mechanisms, which among others involve Heat Shock Proteins of the A family (HSPA/HSP70). This group of highly homologous chaperones and proteostasis-controlling factors includes HSPA2, a unique member crucial for spermatogenesis and implicated in the regulation of keratinocyte differentiation. HIF-1 can control the HSPA2 gene expression. In this study, we revealed that HIF-1α is the first confirmed client of HSPA2 in human somatic cells. It colocalises and interacts directly with HSPA2 in the epidermis in situ and immortalised keratinocytes in vitro. Using an in vitro model based on HSPA2-overexpressing and HSPA2-deficient variants of immortalised keratinocytes we showed that changes in HSPA2 levels do not affect the levels and intracellular localisation of HIF-1α or influence the ability of HIF-1 to modulate target gene expression. However, HIF-1α stability in keratinocytes appears critically reliant on HSPAs as a group of functionally overlapping chaperones. In addition to HSPA2, HIF-1α colocalises and forms complexes with HSPA8 and HSPA1, representing housekeeping and stress-inducible HSPA family paralogs, respectively. Chemical inhibition of HSPA activity, but not paralog-specific knockdown of HSPA8 or HSPA1 expression reduced HIF-1α levels and HIF-1-dependent gene expression. These observations suggest that pharmacological targeting of HSPAs could prevent excessive HIF-1 signalling in pathological skin conditions.

Heat shock factor 1 inhibition enhances the effects of modulated electro hyperthermia in a triple negative breast cancer mouse model

Female breast cancer is the most diagnosed cancer worldwide. Triple negative breast cancer (TNBC) is the most aggressive type and there is no existing endocrine or targeted therapy. Modulated electro-hyperthermia (mEHT) is a non-invasive complementary cancer therapy using an electromagnetic field generated by amplitude modulated 13.56 MHz frequency that induces tumor cell destruction. However, we have demonstrated a strong induction of the heat shock response (HSR) by mEHT, which can result in thermotolerance. We hypothesized that inhibition of the heat shock factor 1 (HSF1) can synergize with mEHT and enhance tumor cell-killing. Thus, we either knocked down the HSF1 gene with a CRISPR/Cas9 lentiviral construct or inhibited HSF1 with a specific small molecule inhibitor: KRIBB11 in vivo. Wild type or HSF1-knockdown 4T1 TNBC cells were inoculated into the mammary gland's fat pad of BALB/c mice. Four mEHT treatments were performed every second day and the tumor growth was followed by ultrasound and caliper. KRIBB11 was administrated intraperitoneally at 50 mg/kg daily for 8 days. HSF1 and Hsp70 expression were assessed. HSF1 knockdown sensitized transduced cancer cells to mEHT and reduced tumor growth. HSF1 mRNA expression was significantly reduced in the KO group when compared to the empty vector group, and consequently mEHT-induced Hsp70 mRNA upregulation diminished in the KO group. Immunohistochemistry (IHC) confirmed the inhibition of Hsp70 upregulation in mEHT HSF1-KO group. Demonstrating the translational potential of HSF1 inhibition, combined therapy of mEHT with KRIBB11 significantly reduced tumor mass compared to either monotherapy. Inhibition of Hsp70 upregulation by mEHT was also supported by qPCR and IHC. In conclusion, we suggest that mEHT-therapy combined with HSF1 inhibition can be a possible new strategy of TNBC treatment with great translational potential.

Targeting the heat shock response induced by modulated electro-hyperthermia (mEHT) in cancer

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.

Heat shock factor 1 drives regulatory T-cell induction to limit murine intestinal inflammation

The heat shock response is a critical component of the inflammatory cascade that prevents misfolding of new proteins and regulates immune responses. Activation of clusters of differentiation (CD)4+ T cells causes an upregulation of heat shock transcription factor, heat shock factor 1 (HSF1). We hypothesized that HSF1 promotes a pro-regulatory phenotype during inflammation. To validate this hypothesis, we interrogated cell-specific HSF1 knockout mice and HSF1 transgenic mice using in vitro and in vivo techniques. We determined that while HSF1 expression was induced by anti-CD3 stimulation alone, the combination of anti-CD3 and transforming growth factor β, a vital cytokine for regulatory T cell (Treg) development, resulted in increased activating phosphorylation of HSF1, leading to increased nuclear translocation and binding to heat shock response elements. Using chromatin immunoprecipitation (ChIP), we demonstrate the direct binding of HSF1 to foxp3 in isolated murine CD4+ T cells, which in turn coincided with induction of FoxP3 expression. We defined that conditional knockout of HSF1 decreased development and function of Tregs and overexpression of HSF1 led to increased expression of FoxP3 along with enhanced Treg suppressive function. Adoptive transfer of CD45RBHigh CD4 colitogenic T cells along with HSF1 transgenic CD25+ Tregs prevented intestinal inflammation when wild-type Tregs did not. Finally, overexpression of HSF1 provided enhanced barrier function and protection from murine ileitis. This study demonstrates that HSF1 promotes Treg development and function and may represent both a crucial step in the development of induced regulatory T cells and an exciting target for the treatment of inflammatory diseases with a regulatory T-cell component. SIGNIFICANCE STATEMENT: The heat shock response (HSR) is a canonical stress response triggered by a multitude of stressors, including inflammation. Evidence supports the role of the HSR in regulating inflammation, yet there is a paucity of data on its influence in T cells specifically. Gut homeostasis reflects a balance between regulatory clusters of differentiation (CD)4+ T cells and pro-inflammatory T-helper (Th)17 cells. We show that upon activation within T cells, heat shock factor 1 (HSF1) translocates to the nucleus, and stimulates Treg-specific gene expression. HSF1 deficiency hinders Treg development and function and conversely, HSF1 overexpression enhances Treg development and function. While this work, focuses on HSF1 as a novel therapeutic target for intestinal inflammation, the findings have significance for a broad range of inflammatory conditions.

Heat Shock Factor 1 Inhibition: A Novel Anti-Cancer Strategy with Promise for Precision Oncology

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.

Proteomics analysis of carotid body tumor revealed potential mechanisms and molecular differences among Shamblin classifications

Carotid body tumors (CBTs) are a rare type of paraganglioma, and surgical resection is the only effective treatment. Because of the proximity of CBTs to the carotid artery, jugular vein, and cranial nerve, surgery is extremely difficult, with high risks of hemorrhage and neurovascular injury. The Shamblin classification is used for CBT clinical evaluation; however, molecular mechanisms underlying classification differences remain unclear. This study aimed to investigate pathogenic mechanisms and molecular differences between CBT types. In Shamblin I, II, and III tumors, differentially expressed proteins (DEPs) were identified using direct data-independent acquisition (DIA). DEPs were validated using immunohistochemistry. Proteomics profiling of three Shamblin subtypes differed significantly. Bioinformatics analysis showed that adrenomedullin signaling, protein kinase A signaling, vascular endothelial growth factor (VEGF) signaling, ephrin receptor signaling, gap junction signaling, interleukin (IL)-1 signaling, actin cytoskeleton signaling, endothelin-1 signaling, angiopoietin signaling, peroxisome proliferator-activated receptor (PPAR) signaling, bone morphogenetic protein (BMP) signaling, hypoxia-inducible factor 1-alpha (HIF-1α) signaling, and IL-6 signaling pathways were significantly enriched. Furthermore, 60 DEPs changed significantly with tumor progression. Immunohistochemistry validated several important DEPs, including aldehyde oxidase 1 (AOX1), mediator complex subunit 22 (MED22), carnitine palmitoyltransferase 1A (CPT1A), and heat shock transcription factor 1 (HSF1). To our knowledge, this is the first application of proteomics quantification in CBT. Our results will deepen the understanding of CBT-related pathogenesis and aid in identifying therapeutic targets for CBT treatment.

The multifunction of HSP70 in cancer: Guardian or traitor to the survival of tumor cells and the next potential therapeutic target

Heat shock protein 70 (HSP70) is a highly conserved protein composed of nucleotide-binding domains (NBD) and C-terminal substrate binding domain (SBD) that can function as a "molecular chaperone". HSP70 was discovered to directly or indirectly play a regulatory role in both internal and external apoptosis pathways. Studies have shown that HSP70 can not only promote tumor progression, enhance tumor cell resistance and inhibit anticancer effects but also induce an anticancer response by activating immune cells. In addition, chemotherapy, radiotherapy and immunotherapy for cancer may be affected by HSP70, which has shown promising potential as an anticancer drug. In this review, we summarized the molecular structure and mechanism of HSP70 and discussed the dual effects of HSP70 on tumor cells and the possibility and potential methods of using HSP70 as a target to treat cancer.

Regulatory Functions of Hypoxia in Host-Parasite Interactions: A Focus on Enteric, Tissue, and Blood Protozoa

Body tissues are subjected to various oxygenic gradients and fluctuations and hence can become transiently hypoxic. Hypoxia-inducible factor (HIF) is the master transcriptional regulator of the cellular hypoxic response and is capable of modulating cellular metabolism, immune responses, epithelial barrier integrity, and local microbiota. Recent reports have characterized the hypoxic response to various infections. However, little is known about the role of HIF activation in the context of protozoan parasitic infections. Growing evidence suggests that tissue and blood protozoa can activate HIF and subsequent HIF target genes in the host, helping or hindering their pathogenicity. In the gut, enteric protozoa are adapted to steep longitudinal and radial oxygen gradients to complete their life cycle, yet the role of HIF during these protozoan infections remains unclear. This review focuses on the hypoxic response to protozoa and its role in the pathophysiology of parasitic infections. We also discuss how hypoxia modulates host immune responses in the context of protozoan infections.

FoxA2 represses ERβ-mediated pyroptosis in endometriosis by transcriptionally inhibiting IGF2BP1

BACKGROUND

Endometriosis is a severe disease which is associated with excessive activation of pyroptosis. Our present research aimed to investigate the function of Forkhead Box A2 (FoxA2) in regulating pyroptosis in endometriosis.

METHODS

IL-1β and IL-18 concentrations were assessed using ELISA. Cell pyroptosis was analyzed using flow cytometry. TUNEL staining was performed to determine human endometrial stromal cells (HESC) death. Moreover, ERβ mRNA stability was assessed using RNA degradation assay. Finally, the binding relationships between FoxA2, IGF2BP1 and ERβ were verified by dual-luciferase reporter system, ChIP, RIP and RNA pull-down assays.

RESULTS

Our results revealed that IGF2BP1 and ERβ were significantly upregulated in ectopic endometrium (EC) tissues of endometriosis patients compared to that in eutopic endometrium (EU) tissues as well as IL-18 and IL-1β levels. Loss-of-function experiments subsequently demonstrated that either IGF2BP1 knockdown or ERβ knockdown could repress HESC pyroptosis. In addition, IGF2BP1 upregulation promoted the pyroptosis in endometriosis by binding to ERβ and promoting ERβ mRNA stability. Our further research displayed that FoxA2 upregulation suppressed HESC pyroptosis by interacting with IGF2BP1 promoter.

CONCLUSION

Our research proved that FoxA2 upregulation downregulated ERβ by transcriptionally inhibiting IGF2BP1, thereby repressing pyroptosis in endometriosis.

HSF1 and Its Role in Huntington's Disease Pathology

PURPOSE OF REVIEW

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.

DATA SOURCES

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.

STUDY SELECTIONS

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

RESULTS

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.

CONCLUSION

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.

RNA binding proteins (RBPs) and their role in DNA damage and radiation response in cancer

Traditionally majority of eukaryotic gene expression is influenced by transcriptional and post-transcriptional events. Alterations in the expression of proteins that act post-transcriptionally can affect cellular signaling and homeostasis. RNA binding proteins (RBPs) are a family of proteins that specifically bind to RNAs and are involved in post-transcriptional regulation of gene expression and important cellular processes such as cell differentiation and metabolism. Deregulation of RNA-RBP interactions and any changes in RBP expression or function can lead to various diseases including cancer. In cancer cells, RBPs play an important role in regulating the expression of tumor suppressors and oncoproteins involved in various cell-signaling pathways. Several RBPs such as HuR, AUF1, RBM38, LIN28, RBM24, tristetrapolin family and Musashi play critical roles in various types of cancers and their aberrant expression in cancer cells makes them an attractive therapeutic target for cancer treatment. In this review we provide an overview of i). RBPs involved in cancer progression and their mechanism of action ii). the role of RBPs, including HuR, in breast cancer progression and DNA damage response and iii). explore RBPs with emphasis on HuR as therapeutic target for breast cancer therapy.

A systematic study of HIF1A cofactors in hypoxic cancer cells

Hypoxia inducible factor 1 alpha (HIF1A) is a transcription factor (TF) that forms highly structural and functional protein-protein interactions with other TFs to promote gene expression in hypoxic cancer cells. However, despite the importance of these TF-TF interactions, we still lack a comprehensive view of many of the TF cofactors involved and how they cooperate. In this study, we systematically studied HIF1A cofactors in eight cancer cell lines using the computational motif mining tool, SIOMICS, and discovered 201 potential HIF1A cofactors, which included 21 of the 29 known HIF1A cofactors in public databases. These 201 cofactors were statistically and biologically significant, with 19 of the top 37 cofactors in our study directly validated in the literature. The remaining 18 were novel cofactors. These discovered cofactors can be essential to HIF1A's regulatory functions and may lead to the discovery of new therapeutic targets in cancer treatment.

Circadian disruption enhances HSF1 signaling and tumorigenesis in Kras-driven lung cancer

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.

Cytoplasmic proteotoxicity regulates HRI-dependent phosphorylation of eIF2α via the Hsp70-Bag3 module

The major heat shock protein Hsp70 forms a complex with a scaffold protein Bag3 that links it to components of signaling pathways. Via these interactions, the Hsp70-Bag3 module functions as a proteotoxicity sensor that controls cell signaling. Here, to search for pathways regulated by the complex, we utilized JG-98, an allosteric inhibitor of Hsp70 that blocks its interaction with Bag3. RNAseq followed by the pathway analysis indicated that several signaling pathways including UPR were activated by JG-98. Surprisingly, only the eIF2α-associated branch of the UPR was activated, while other UPR branches were not induced, suggesting that the response was unrelated to the ER proteotoxicity and ER-associated kinase PERK1. Indeed, induction of the UPR genes under these conditions was driven by a distinct eIF2α kinase HRI. Hsp70-Bag3 directly interacted with HRI and regulated eIF2α phosphorylation upon cytoplasmic proteotoxicity. Therefore, cytosolic proteotoxicity can activate certain UPR genes via Hsp70-Bag3-HRI-eIF2α axis.

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Disruption of Hsp70-Bag3 module activates the unfolded protein response (UPR)

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This induction of UPR genes is mediated by HRI-dependent phosphorylation of eIF2α

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Hsp70-Bag3 “monitors” cytoplasmic proteotoxicity to activate the HRI-eIF2α axis

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eIF2α integrates proteotoxicity signals from ER and cytoplasm

Insight into the mitochondrial unfolded protein response and cancer: opportunities and challenges

The mitochondrial unfolded protein response (UPR^mt) is an evolutionarily conserved protective transcriptional response that maintains mitochondrial proteostasis by inducing the expression of mitochondrial chaperones and proteases in response to various stresses. The UPR^mt-mediated transcriptional program requires the participation of various upstream signaling pathways and molecules. The factors regulating the UPR^mt in Caenorhabditis elegans (C. elegans) and mammals are both similar and different. Cancer cells, as malignant cells with uncontrolled proliferation, are exposed to various challenges from endogenous and exogenous stresses. Therefore, in cancer cells, the UPR^mt is hijacked and exploited for the repair of mitochondria and the promotion of tumor growth, invasion and metastasis. In this review, we systematically introduce the inducers of UPR^mt, the biological processes in which UPR^mt participates, the mechanisms regulating the UPR^mt in C. elegans and mammals, cross-tissue signal transduction of the UPR^mt and the roles of the UPR^mt in promoting cancer initiation and progression. Disrupting proteostasis in cancer cells by targeting UPR^mt constitutes a novel anticancer therapeutic strategy.

Heat shock transcription factor HSF2 modulates the autophagy response through the BTG2-SOD2 axis

The heat shock transcription factor HSF1 regulates the inducible Hsp gene transcription, whereas HSF2 is involved in the constitutive transcription. HSFs can work for the non-heat shock genes transcription in a case-specific manner to facilitate normal cellular functions. Here, we demonstrate that HSF2 acts as an upstream regulator of heat shock-induced autophagy response in a rat histiocytoma. The heat-induced HSF2 transactivates the B-cell translocation gene-2 (BTG2) transcription, and the latter acts as a transcriptional coactivator for superoxide dismutase (SOD2). The altered HSF2 promoter occupancy on the BTG2 promoter enhances BTG2 transcription. Since SOD2 regulation is linked to mitochondrial redox sensing, HSF2 appears to act as a redox sensor in deciding the cell fate. The HSF2 shRNA or NFE2L2/BTG2 siRNA treatments have interfered with the autophagy response. We demonstrate that HSF2 is an upstream activator of autophagy response, and the HSF2-BTG2-SOD2 axis acts as a switch between the non-selective (micro/macro) and selective (chaperone-mediated) autophagy.

HuR-targeted agents: An insight into medicinal chemistry, biophysical, computational studies and pharmacological effects on cancer models

The Human antigen R (HuR) protein is an RNA-binding protein, ubiquitously expressed in human tissues, that orchestrates target RNA maturation and processing both in the nucleus and in the cytoplasm. A survey of known modulators of the RNA-HuR interactions is followed by a description of its structure and molecular mechanism of action - RRM domains, interactions with RNA, dimerization, binding modes with naturally occurring and synthetic HuR inhibitors. Then, the review focuses on HuR as a validated molecular target in oncology and briefly describes its role in inflammation. Namely, we show ample evidence for the involvement of HuR in the hallmarks and enabling characteristics of cancer, reporting findings from in vitro and in vivo studies; and we provide abundant experimental proofs of a beneficial role for the inhibition of HuR-mRNA interactions through silencing (CRISPR, siRNA) or pharmacological inhibition (small molecule HuR inhibitors).

Integrated bioinformatics and experiments reveal the roles and driving forces for HSF1 in colorectal cancer

Heat shock factor 1 (HSF1) has watershed significance in different tumors. However, the roles and driving forces for HSF1 in colorectal cancer (CRC) are poorly understood. Our study integrally analyzed the roles and driving forces for HSF1 in CRC by bioinformatics and experiments. The expression and prognostic characteristics of HSF1 were analyzed via UALCAN, GEPIA2, TISIDB, Prognoscan and HPA databases. Then, we analyzed the correlation between HSF1 expression and immune features via TIMER2 database. Subsequently, we explored the driving forces for HSF1 abnormal expression in CRC by bioinformatics and experiments. Our results showed that HSF1 was overexpressed and correlated with poor prognosis in CRC. And the expression of HSF1 was significantly correlated with multiple immune cell infiltration and was negatively correlated with immunomodulators such as programmed cell death 1 ligand 1(PD-L1). Along with many driver genes in particular TP53, super-enhancer, miRNA and DNA methylation were all responsible for HSF1 overexpression in CRC. Moreover, we demonstrated that β-catenin could promote the translation process of HSF1 mRNA by interacting with HuR, which could directly bind to the coding sequence (CDS) region of HSF1 mRNA. Collectively, HSF1 may be useful as a diagnostic and prognostic biomarker for CRC. HSF1 was closely correlated with immune features. Genetic and epigenetic alterations contributed to HSF1 overexpression in CRC. More importantly, we demonstrated that HSF1 may be regulated at the level of mRNA translation by β-catenin-induced HuR activity.

Drug delivery approaches for HuR-targeted therapy for lung cancer

Lung cancer (LC) is often diagnosed at an advanced stage and conventional treatments for disease management have limitations associated with them. Novel therapeutic targets are thus avidly sought for the effective management of LC. RNA binding proteins (RBPs) have been convincingly established as key players in tumorigenesis, and their dysregulation is linked to multiple cancers, including LC. In this context, we review the role of Human antigen R (HuR), an RBP that is overexpressed in LC, and further associated with various aspects of LC tumor growth and response to therapy. Herein, we describe the role of HuR in LC progression and outline the evidences supporting various pharmacologic and biologic approaches for inhibiting HuR expression and function. These approaches, including use of small molecule inhibitors, siRNAs and shRNAs, have demonstrated favorable results in reducing tumor cell growth, invasion and migration, angiogenesis and metastasis. Hence, HuR has significant potential as a key therapeutic target in LC. Use of siRNA-based approaches, however, have certain limitations that prevent their maximal exploitation as cancer therapies. To address this, in the conclusion of this review, we provide a list of nanomedicine-based HuR targeting approaches currently being employed for siRNA and shRNA delivery, and provide a rationale for the immense potential therapeutic benefits offered by nanocarrier-based HuR targeting and its promise for treating patients with LC.

Multifaceted roles of HSF1 in cell death: A state-of-the-art review

Cell death is a common and active process that is involved in various biological processes, including organ development, morphogenesis, maintaining tissue homeostasis and eliminating potentially harmful cells. Abnormal regulation of cell death significantly contributes to tumor development, progression and chemoresistance. The mechanisms of cell death are complex and involve not only apoptosis and necrosis but also their cross-talk with other types of cell death, such as autophagy and the newly identified ferroptosis. Cancer cells are chronically exposed to various stresses, such as lack of oxygen and nutrients, immune responses, dysregulated metabolism and genomic instability, all of which lead to activation of heat shock factor 1 (HSF1). In response to heat shock, oxidative stress and proteotoxic stresses, HSF1 upregulates transcription of heat shock proteins (HSPs), which act as molecular chaperones to protect normal cells from stresses and various diseases. Accumulating evidence suggests that HSF1 regulates multiple types of cell death through different signaling pathways as well as expression of distinct target genes in cancer cells. Here, we review the current understanding of the potential roles and molecular mechanism of HSF1 in regulating apoptosis, autophagy and ferroptosis. Deciphering HSF1-regulated signaling pathways and target genes may help in the development of new targeted anti-cancer therapeutic strategies.

Is cancer a disease set up by cellular stress responses?

For several decades, the somatic mutation theory (SMT) has been the dominant paradigm on cancer research, leading to the textbook notion that cancer is fundamentally a genetic disease. However, recent discoveries indicate that mutations, including "oncogenic" ones, are widespread in normal somatic cells, suggesting that mutations may be necessary but not sufficient for cancer to develop. Indeed, a fundamental but as yet unanswered question is whether or not the first step in oncogenesis corresponds to a mutational event. On the other hand, for some time, it has been acknowledged the important role in cancer progression of molecular processes that participate in buffering cellular stress. However, their role is considered secondary or complementary to that of putative oncogenic mutations. Here we present and discuss evidence that cancer may have its origin in epigenetic processes associated with cellular adaptation to stressful conditions, and so it could be a direct consequence of stress-buffering mechanisms that allow cells with aberrant phenotypes (not necessarily associated with genetic mutations) to survive and propagate within the organism. We put forward the hypothesis that there would be an inverse correlation between the activation threshold of the cellular stress responses (CSRs) and the risk of cancer, so that species or individuals with low-threshold CSRs will display a higher incidence or risk of cancer.

HuR as Therapeutic Target in Cancer: What the Future Holds

ELAV-like protein 1, or HuR (human antigen R), is an RNA-binding protein encoded by the ELAVL1 gene in humans. One of its best functions is to stabilize mRNAs in order to regulate gene expression. HuR protein overexpression has undoubtedly been linked to an increased risk of tumor growth, progression, and metastasis, rendering it a potential therapeutic target candidate in cancer. Novel agents interfering with HuR expression have been tested, both in vitro and in vivo, with promising results. The aim of this paper is to review the existing literature regarding the potential agents that could actively act on and inhibit HuR expression. HuR molecule controls the expression of various proto-oncogenes, cytokines and growth factors, representing a major player in tumor progression, invasion, and metastasis and constituting an emerging target for cancer therapy. PubMed database was thoroughly searched, and all published articles providing scientific data on molecules that can exhibit antitumorigenic effects via HuR inhibition were included. According to these data, HuR inhibition should be a promising target in cancer therapeutics.

Hypoxia-Induced Cancer Cell Responses Driving Radioresistance of Hypoxic Tumors: Approaches to Targeting and Radiosensitizing

Simple Summary

Some regions of aggressive malignancies experience hypoxia due to inadequate blood supply. Cancer cells adapting to hypoxic conditions somehow become more resistant to radiation exposure and this decreases the efficacy of radiotherapy toward hypoxic tumors. The present review article helps clarify two intriguing points: why hypoxia-adapted cancer cells turn out radioresistant and how they can be rendered more radiosensitive. The critical molecular targets associated with intratumoral hypoxia and various approaches are here discussed which may be used for sensitizing hypoxic tumors to radiotherapy.

Abstract

Within aggressive malignancies, there usually are the “hypoxic zones”—poorly vascularized regions where tumor cells undergo oxygen deficiency through inadequate blood supply. Besides, hypoxia may arise in tumors as a result of antiangiogenic therapy or transarterial embolization. Adapting to hypoxia, tumor cells acquire a hypoxia-resistant phenotype with the characteristic alterations in signaling, gene expression and metabolism. Both the lack of oxygen by itself and the hypoxia-responsive phenotypic modulations render tumor cells more radioresistant, so that hypoxic tumors are a serious challenge for radiotherapy. An understanding of causes of the radioresistance of hypoxic tumors would help to develop novel ways for overcoming this challenge. Molecular targets for and various approaches to radiosensitizing hypoxic tumors are considered in the present review. It is here analyzed how the hypoxia-induced cellular responses involving hypoxia-inducible factor-1, heat shock transcription factor 1, heat shock proteins, glucose-regulated proteins, epigenetic regulators, autophagy, energy metabolism reprogramming, epithelial–mesenchymal transition and exosome generation contribute to the radioresistance of hypoxic tumors or may be inhibited for attenuating this radioresistance. The pretreatments with a multitarget inhibition of the cancer cell adaptation to hypoxia seem to be a promising approach to sensitizing hypoxic carcinomas, gliomas, lymphomas, sarcomas to radiotherapy and, also, liver tumors to radioembolization.

Targeting therapy-resistant prostate cancer via a direct inhibitor of the human heat shock transcription factor 1

Heat shock factor 1 (HSF1) is a cellular stress-protective transcription factor exploited by a wide range of cancers to drive proliferation, survival, invasion, and metastasis. Nuclear HSF1 abundance is a prognostic indicator for cancer severity, therapy resistance, and shortened patient survival. The HSF1 gene was amplified, and nuclear HSF1 abundance was markedly increased in prostate cancers and particularly in neuroendocrine prostate cancer (NEPC), for which there are no available treatment options. Despite genetic validation of HSF1 as a therapeutic target in a range of cancers, a direct and selective small-molecule HSF1 inhibitor has not been validated or developed for use in the clinic. We described the identification of a direct HSF1 inhibitor, Direct Targeted HSF1 InhiBitor (DTHIB), which physically engages HSF1 and selectively stimulates degradation of nuclear HSF1. DTHIB robustly inhibited the HSF1 cancer gene signature and prostate cancer cell proliferation. In addition, it potently attenuated tumor progression in four therapy-resistant prostate cancer animal models, including an NEPC model, where it caused profound tumor regression. This study reports the identification and validation of a direct HSF1 inhibitor and provides a path for the development of a small-molecule HSF1-targeted therapy for prostate cancers and other therapy-resistant cancers.

HSF1 as a Cancer Biomarker and Therapeutic Target

Heat shock factor 1 (HSF1) was discovered in 1984 as the master regulator of the heat shock response. In this classical role, HSF1 is activated following cellular stresses such as heat shock that ultimately lead to HSF1-mediated expression of heat shock proteins to protect the proteome and survive these acute stresses. However, it is now becoming clear that HSF1 also plays a significant role in several diseases, perhaps none more prominent than cancer. HSF1 appears to have a pleiotropic role in cancer by supporting multiple facets of malignancy including migration, invasion, proliferation, and cancer cell metabolism among others. Because of these functions, and others, of HSF1, it has been investigated as a biomarker for patient outcomes in multiple cancer types. HSF1 expression alone was predictive for patient outcomes in multiple cancer types but in other instances, markers for HSF1 activity were more predictive. Clearly, further work is needed to tease out which markers are most representative of the tumor promoting effects of HSF1. Additionally, there have been several attempts at developing small molecule inhibitors to reduce HSF1 activity. All of these HSF1 inhibitors are still in preclinical models but have shown varying levels of efficacy at suppressing tumor growth. The growth of research related to HSF1 in cancer has been enormous over the last decade with many new functions of HSF1 discovered along the way. In order for these discoveries to reach clinical impact, further development of HSF1 as a biomarker or therapeutic target needs to be continued.

The RNA-Binding Protein HuR in Digestive System Tumors

Human antigen R (HuR) is a member of the Hu family of RNA-binding proteins. This molecule, which was first described in tumors nearly two decades ago, has recently received much attention in tumor-related research because it regulates the expression of many tumor-associated molecules through posttranscriptional regulatory mechanisms, thereby affecting biological characteristics. It is suggested that HuR might be a novel therapeutic target and a marker for therapeutic response and prognostic assessment. Increasing evidence supports that HuR also plays critical roles in the development, therapy, and prognosis of digestive system tumors. Herein, we review the relationships between HuR and digestive system tumors, demonstrating the importance of HuR in digestive system tumor diagnosis.

Emerging roles of HSF1 in cancer: Cellular and molecular episodes

Heat shock factor 1 (HSF1) systematically guards proteome stability and proteostasis by regulating the expression of heat shock protein (HSP), thus rendering cancer cells addicted to HSF1. The non-canonical transcriptional programme driven by HSF1, which is distinct from the heat shock response (HSR), plays an indispensable role in the initiation, promotion and progression of cancer. Therefore, HSF1 is widely exploited as a potential therapeutic target in a broad spectrum of cancers. Various molecules and signals in the cell jointly regulate the activation and attenuation of HSF1. The high-level expression of HSF1 in tumours and its relationship with patient prognosis imply that HSF1 can be used as a biomarker for patient prognosis and a target for cancer treatment. In this review, we discuss the newly identified mechanisms of HSF1 activation and regulation, the diverse functions of HSF1 in tumourigenesis, and the feasibility of using HSF1 as a prognostic marker. Disrupting cancer cell proteostasis by targeting HSF1 represents a novel anti-cancer therapeutic strategy.

Molecular Mechanisms of Heat Shock Factors in Cancer

Malignant transformation is accompanied by alterations in the key cellular pathways that regulate development, metabolism, proliferation and motility as well as stress resilience. The members of the transcription factor family, called heat shock factors (HSFs), have been shown to play important roles in all of these biological processes, and in the past decade it has become evident that their activities are rewired during tumorigenesis. This review focuses on the expression patterns and functions of HSF1, HSF2, and HSF4 in specific cancer types, highlighting the mechanisms by which the regulatory functions of these transcription factors are modulated. Recently developed therapeutic approaches that target HSFs are also discussed.

Hyperthermia and protein homeostasis: Cytoprotection and cell death

Protein homeostasis or proteostasis, the correct balance between production and degradation of proteins, is an essential pillar for proper cellular function. Among the several cellular mechanisms that disrupt homeostatic conditions in cancer cells, hyperthermia (HT) has shown promising anti-tumor effects. However, cancer cells are also capable of thermoresistance. Indeed, HT-induced protein denaturation and aggregation results in the up regulation of heat shock proteins, a group of molecular chaperones with cytoprotective and anti-apoptotic properties via stress-inducible transcription factor, heat shock factor 1(HSF1). Heat shock proteins assist in the refolding of misfolded proteins and aids in their elimination if they become irreversibly damaged by various stressors. Furthermore, HSF1 also initiates the unfolded protein response in the endoplasmic reticulum (ER) to assist in the protein folding capacity of ER and also promotes the translation of pro-survival proteins' mRNA such as activating transcription factor 4 (ATF 4). Moreover, HT associated induction of microRNAs is also involved in thermal resistance of cancer cells via up-regulation of anti-apoptotic Bcl-2 proteins and down regulation of pro-apoptotic Bax and caspase 3 activities. Another cellular protection in response to stressors is Autophagy, which is regulated by the Mammalian target of rapamycin (mTOR) protein. Kinase activity in mTOR phosphorylates HSF1 and promotes its nuclear translocation for heat shock protein synthesis. Over-expression of heat shock proteins are reported to up-regulate Beclin-1, an autophagy initiator. Moreover, HT-induced reactive oxygen species (ROS) generation is sensitized by transcription factor NF-E2 related factor 2 (Nrf2) and activates the cellular expression of antioxidants and autophagy gene. Furthermore, ROS also potentiates autophagy via activation of Beclin-1. Inhibition of thermotolerance can potentiate HT-induced apoptosis. Here, we outlined that heat stress alters cellular proteins which activates cellular homeostatic processes to promote cell survival and make cancer cells thermotolerant.

HSF1: Primary Factor in Molecular Chaperone Expression and a Major Contributor to Cancer Morbidity

Heat shock factor 1 (HSF1) is the primary component for initiation of the powerful heat shock response (HSR) in eukaryotes. The HSR is an evolutionarily conserved mechanism for responding to proteotoxic stress and involves the rapid expression of heat shock protein (HSP) molecular chaperones that promote cell viability by facilitating proteostasis. HSF1 activity is amplified in many tumor contexts in a manner that resembles a chronic state of stress, characterized by high levels of HSP gene expression as well as HSF1-mediated non-HSP gene regulation. HSF1 and its gene targets are essential for tumorigenesis across several experimental tumor models, and facilitate metastatic and resistant properties within cancer cells. Recent studies have suggested the significant potential of HSF1 as a therapeutic target and have motivated research efforts to understand the mechanisms of HSF1 regulation and develop methods for pharmacological intervention. We review what is currently known regarding the contribution of HSF1 activity to cancer pathology, its regulation and expression across human cancers, and strategies to target HSF1 for cancer therapy.

HSP70 Multi-Functionality in Cancer

The 70-kDa heat shock proteins (HSP70s) are abundantly present in cancer, providing malignant cells selective advantage by suppressing multiple apoptotic pathways, regulating necrosis, bypassing cellular senescence program, interfering with tumor immunity, promoting angiogenesis and supporting metastasis. This direct involvement of HSP70 in most of the cancer hallmarks explains the phenomenon of cancer "addiction" to HSP70, tightly linking tumor survival and growth to the HSP70 expression. HSP70 operates in different states through its catalytic cycle, suggesting that it can multi-function in malignant cells in any of these states. Clinically, tumor cells intensively release HSP70 in extracellular microenvironment, resulting in diverse outcomes for patient survival. Given its clinical significance, small molecule inhibitors were developed to target different sites of the HSP70 machinery. Furthermore, several HSP70-based immunotherapy approaches were assessed in clinical trials. This review will explore different roles of HSP70 on cancer progression and emphasize the importance of understanding the flexibility of HSP70 nature for future development of anti-cancer therapies.

Heat shock transcription factor 1 regulates exercise-induced myocardial angiogenesis after pressure overload via HIF-1α/VEGF pathway

Exercise training is believed to have a positive effect on cardiac hypertrophy after hypertension. However, its mechanism is still not fully understood. Herein, our findings suggest that heat shock transcription factor 1 (HSF1) improves exercise‐initiated myocardial angiogenesis after pressure overload. A sustained narrowing of the diagonal aorta (TAC) and moderately‐ intense exercise training protocol were imposed on HSF1 heterozygote (KO) and their littermate wild‐type (WT) male mice. After two months, the cardiac function was assessed using the adaptive responses to exercise training, or TAC, or both of them such as catheterization and echocardiography. The HE stains assessed the area of myocyte cross‐sectional. The Western blot and real‐time PCR measured the levels of expression for heat shock factor 1 (HSF1), vascular endothelial growth factor (VEGF) and hypoxia inducible factor‐1 alpha (HIF‐1α) in cardiac tissues. The anti‐CD31 antibody immunohistochemical staining was done to examine how exercise training influenced cardiac ontogeny. The outcome illustrated that exercise training significantly improved the cardiac ontogeny in TAC mice, which was convoyed by elevated levels of expression for VEGF and HIF‐1α and preserved the heart microvascular density. More importantly, HSF1 deficiency impaired these effects induced by exercise training in TAC mice. In conclusion, exercise training encourages cardiac ontogeny by means of HSF1 activation and successive HIF‐1α/VEGF up‐regulation in endothelial cells during continued pressure overload.

The Multifaceted Role of HSF1 in Tumorigenesis

Heat Shock Factor 1 (HSF1), the master transcriptional regulator of the heat shock response (HSR), was first cloned more than 30 years ago. Most early research interrogating the role that HSF1 plays in biology focused on its cytoprotective functions, as a factor that promotes the survival of organisms by protecting against the proteotoxicity associated with neurodegeneration and other pathological conditions. However, recent studies have revealed a deleterious role of HSF1, as a factor that is co-opted by cancer cells to promote their own survival to the detriment of the organism. In cancer, HSF1 operates in a multifaceted manner to promote oncogenic transformation, proliferation, metastatic dissemination, and anti-cancer drug resistance. Here we review our current understanding of HSF1 activation and function in malignant progression and discuss the potential for HSF1 inhibition as a novel anticancer strategy. Collectively, this ever-growing body of work points to a prominent role of HSF1 in nearly every aspect of carcinogenesis.

HSF2 regulates aerobic glycolysis by suppression of FBP1 in hepatocellular carcinoma

Heat shock factors (HSFs) are essential for all organisms to survive exposures to acute stress. Recent years have witnessed the progress in uncovering the importance of HSFs in cancer cell oncogenesis, progression and metastasis. However, their roles in hepatocellular carcinoma (HCC) proliferation and the underlying mechanism have seldom been discussed. The present study aims to uncover the two important HSFs members HSF1 and HSF2 in hepatocellular carcinoma (HCC). By using the Cancer Genome Atlas (TCGA) dataset analysis, we investigated the prognosis value of HSF1 and HSF2 in HCC and identified HSF2 as a prediction factor of overall survival of HCC. In vitro cell line studies demonstrated that silencing HSF2 expression could decrease the proliferation in HCC cells. In depth mechanism analysis demonstrated that HSF2 promoted cell proliferation via positive regulation of aerobic glycolysis, and HSF2 interacted with euchromatic histone lysine methyltransferase 2 (EHMT2) to epigenetically silence fructose-bisphosphatase 1 (FBP1), which is a tumor suppressor and negative regulator of aerobic glycolysis in HCC. HSF2 expression indicated unfavorable prognosis of HCC patients and it could regulate aerobic glycolysis by suppression of FBP1 to support uncontrolled proliferation of HCC cells.

Prenatal Environment That Affects Neuronal Migration

Migration of neurons starts in the prenatal period and continues into infancy. This developmental process is crucial for forming a proper neuronal network, and the disturbance of this process results in dysfunction of the brain such as epilepsy. Prenatal exposure to environmental stress, including alcohol, drugs, and inflammation, disrupts neuronal migration and causes neuronal migration disorders (NMDs). In this review, we summarize recent findings on this topic and specifically focusing on two different modes of migration, radial, and tangential migration during cortical development. The shared mechanisms underlying the NMDs are discussed by comparing the molecular changes in impaired neuronal migration under exposure to different types of prenatal environmental stress.

Heat shock factor 1 (HSF1)-targeted anticancer therapeutics: overview of current preclinical progress

INTRODUCTION

The heat shock factor 1 (HSF1) plays a pivotal role in guarding proteome stability or proteostasis by induction of heat shock proteins (HSPs). While HSF1 remains mostly latent in unstressed normal cells, it is constitutively active in malignant cells, rendering them addicted to HSF1 for their growth and survival. HSF1 affects tumorigenesis, cancer progression, and treatment resistance by preserving cancer proteostasis, thus suggesting disruption of HSF1 activity as a potential anticancer strategy. Areas covered: In this review, we focus on the HSF1 activation cycle and its interaction with HSPs, the role of HSF1 in oncogenesis, and development of HSF1-targeted drugs as a potential anticancer therapy for disrupting cancer proteostasis. Expert opinion: HSF1 systematically maintains proteostasis in malignant cancer cells. Although genomic instability is widely accepted as a hallmark of cancer, little is known about the role of proteostasis in cancer. Unveiling the complicated mechanism of HSF1 regulation, particularly in cancer cells, will enable further development of proteostasis-targeted anticancer therapy.

ABBREVIATIONS

AMPK: AMP-activated protein kinase; DBD: DNA-binding domain; HR-A/B; HR-C: heptad repeats; HSE: heat shock elements; HSF1: heat shock factor; HSPs: heat shock proteins; HSR: heat shock response; MEK: mitogen-activated protein kinase kinase; mTOR: mammalian target of rapamycin; NF1: neurofibromatosis type 1; P-TEFb: positive transcription elongation factor b; RD: regulatory domain; RNAi: RNA interference; TAD: transactivation domain; TRiC: TCP-1 ring complex.

Dorsomorphin induces cancer cell apoptosis and sensitizes cancer cells to HSP90 and proteasome inhibitors by reducing nuclear heat shock factor 1 levels

Objective

Heat shock factor 1 (HSF1), a transcriptional regulator of heat shock proteins (HSPs), is an attractive therapeutic target for cancer. However, only a few HSF1 inhibitors have been identified so far.

Methods

The mRNA and protein levels of HSF1, HSPs, cleaved PARP, and phosphorylated HSF1 were examined by real-time PCR and Western blot. Forced expression, RNA interference, and immunofluorescence assay were used for mechanistic studies. Cell viability and apoptosis were measured by WST-8 assay and flow cytometry, respectively. Xenograft studies were performed in nude mice to evaluate the effect of dorsomorphin and an HSP90 inhibitor on tumor growth.

Results

Dorsomorphin suppressed multiple stimuli-induced and constitutive HSPs expression in cancer cells. Mechanistic studies revealed that dorsomorphin reduced heat-induced HSP expression independent of adenosine monophosphate activated protein kinase. Dorsomorphin reduced heat-stimulated HSF1 Ser320 phosphorylation and nuclear translocation, as well as resting nuclear HSF1 levels in cancer cells. Dorsomorphin induced cancer cell apoptosis by inhibiting HSF1 expression. A structure-activity study revealed that the 4-pyridyl at the 3-site of the pyrazolo [1, 5-a]pyrimidine ring is critical for the anti-HSF1 activities of dorsomorphin. Dorsomorphin sensitized cancer cells to HSP90 and proteasome inhibitors and inhibited HSP70 expression induced by these inhibitors in vitro. In tumor-bearing nude mice, dorsomorphin enhanced HSP90 inhibitor-induced cancer cell apoptosis, tumor growth inhibition, and HSP70 expression.

Conclusions

Dorsomorphin is an HSF1 inhibitor. It induces cancer cell apoptosis, sensitizes cancer cells to both HSP90 and proteasome inhibitors, and suppresses HSP upregulation by these drugs, which may prevent the development of drug resistance. Hence, dorsomorphin and its derivates may serve as potential precursors for developing drugs against cancer.

Glutamine: Metabolism and Immune Function, Supplementation and Clinical Translation

Glutamine is the most abundant and versatile amino acid in the body. In health and disease, the rate of glutamine consumption by immune cells is similar or greater than glucose. For instance, in vitro and in vivo studies have determined that glutamine is an essential nutrient for lymphocyte proliferation and cytokine production, macrophage phagocytic plus secretory activities, and neutrophil bacterial killing. Glutamine release to the circulation and availability is mainly controlled by key metabolic organs, such as the gut, liver, and skeletal muscles. During catabolic/hypercatabolic situations glutamine can become essential for metabolic function, but its availability may be compromised due to the impairment of homeostasis in the inter-tissue metabolism of amino acids. For this reason, glutamine is currently part of clinical nutrition supplementation protocols and/or recommended for immune suppressed individuals. However, in a wide range of catabolic/hypercatabolic situations (e.g., ill/critically ill, post-trauma, sepsis, exhausted athletes), it is currently difficult to determine whether glutamine supplementation (oral/enteral or parenteral) should be recommended based on the amino acid plasma/bloodstream concentration (also known as glutaminemia). Although the beneficial immune-based effects of glutamine supplementation are already established, many questions and evidence for positive in vivo outcomes still remain to be presented. Therefore, this paper provides an integrated review of how glutamine metabolism in key organs is important to cells of the immune system. We also discuss glutamine metabolism and action, and important issues related to the effects of glutamine supplementation in catabolic situations.

Glutamine: Metabolism and Immune Function, Supplementation and Clinical Translation

Glutamine is the most abundant and versatile amino acid in the body. In health and disease, the rate of glutamine consumption by immune cells is similar or greater than glucose. For instance, in vitro and in vivo studies have determined that glutamine is an essential nutrient for lymphocyte proliferation and cytokine production, macrophage phagocytic plus secretory activities, and neutrophil bacterial killing. Glutamine release to the circulation and availability is mainly controlled by key metabolic organs, such as the gut, liver, and skeletal muscles. During catabolic/hypercatabolic situations glutamine can become essential for metabolic function, but its availability may be compromised due to the impairment of homeostasis in the inter-tissue metabolism of amino acids. For this reason, glutamine is currently part of clinical nutrition supplementation protocols and/or recommended for immune suppressed individuals. However, in a wide range of catabolic/hypercatabolic situations (e.g., ill/critically ill, post-trauma, sepsis, exhausted athletes), it is currently difficult to determine whether glutamine supplementation (oral/enteral or parenteral) should be recommended based on the amino acid plasma/bloodstream concentration (also known as glutaminemia). Although the beneficial immune-based effects of glutamine supplementation are already established, many questions and evidence for positive in vivo outcomes still remain to be presented. Therefore, this paper provides an integrated review of how glutamine metabolism in key organs is important to cells of the immune system. We also discuss glutamine metabolism and action, and important issues related to the effects of glutamine supplementation in catabolic situations.

Roles of heat shock factor 1 beyond the heat shock response

Various stress factors leading to protein damage induce the activation of an evolutionarily conserved cell protective mechanism, the heat shock response (HSR), to maintain protein homeostasis in virtually all eukaryotic cells. Heat shock factor 1 (HSF1) plays a central role in the HSR. HSF1 was initially known as a transcription factor that upregulates genes encoding heat shock proteins (HSPs), also called molecular chaperones, which assist in refolding or degrading injured intracellular proteins. However, recent accumulating evidence indicates multiple additional functions for HSF1 beyond the activation of HSPs. Here, we present a nearly comprehensive list of non-HSP-related target genes of HSF1 identified so far. Through controlling these targets, HSF1 acts in diverse stress-induced cellular processes and molecular mechanisms, including the endoplasmic reticulum unfolded protein response and ubiquitin-proteasome system, multidrug resistance, autophagy, apoptosis, immune response, cell growth arrest, differentiation underlying developmental diapause, chromatin remodelling, cancer development, and ageing. Hence, HSF1 emerges as a major orchestrator of cellular stress response pathways.

Integrated phosphorescence-based photonic biosensor (iPOB) for monitoring oxygen levels in 3D cell culture systems

Physiological processes, such as respiration, circulation, digestion, and many pathologies alter oxygen concentration in the blood and tissue. When designing culture systems to recapitulate the in vivo oxygen environment, it is important to integrate systems for monitoring and controlling oxygen concentration. Herein, we report the design and engineering of a system to remotely monitor and control oxygen concentration inside a device for 3D cell culture. We integrate a photonic oxygen biosensor into the 3D tissue scaffold and regulate oxygen concentration via the control of purging gas flow. The integrated phosphorescence-based oxygen biosensor employs the quenching of palladium-benzoporphyrin by molecular oxygen to transduce the local oxygen concentration in the 3D tissue scaffold. The system is validated by testing the effects of normoxic and hypoxic culture conditions on healthy and tumorigenic breast epithelial cells, MCF-10A cells and BT474 cells, respectively. Under hypoxic conditions, both cell types exhibited upregulation of downstream target genes for the hypoxia marker gene, hypoxia-inducible factor 1α (HIF1A). Lastly, by monitoring the real-time fluctuation of oxygen concentration, we illustrated the formation of hypoxic culture conditions due to limited diffusion of oxygen through 3D tissue scaffolds.

The heat-shock, or HSF1-mediated proteotoxic stress, response in cancer: from proteomic stability to oncogenesis

The heat-shock, or HSF1-mediated proteotoxic stress, response (HSR/HPSR) is characterized by induction of heat-shock proteins (HSPs). As molecular chaperones, HSPs facilitate the folding, assembly, transportation and degradation of other proteins. In mammals, heat shock factor 1 (HSF1) is the master regulator of this ancient transcriptional programme. Upon proteotoxic insults, the HSR/HPSR is essential to proteome homeostasis, or proteostasis, thereby resisting stress and antagonizing protein misfolding diseases and ageing. Contrasting with these benefits, an unexpected pro-oncogenic role of the HSR/HPSR is unfolding. Whereas HSF1 remains latent in primary cells without stress, it becomes constitutively activated within malignant cells, rendering them addicted to HSF1 for their growth and survival. Highlighting the HSR/HPSR as an integral component of the oncogenic network, several key pathways governing HSF1 activation by environmental stressors are causally implicated in malignancy. Importantly, HSF1 impacts the cancer proteome systemically. By suppressing tumour-suppressive amyloidogenesis, HSF1 preserves cancer proteostasis to support the malignant state, both providing insight into how HSF1 enables tumorigenesis and suggesting disruption of cancer proteostasis as a therapeutic strategy. This review provides an overview of the role of HSF1 in oncogenesis, mechanisms underlying its constitutive activation within cancer cells and its pro-oncogenic action, as well as potential HSF1-targeting strategies.This article is part of the theme issue 'Heat shock proteins as modulators and therapeutic targets of chronic disease: an integrated perspective'.

HSF1 Is Essential for Myeloma Cell Survival and A Promising Therapeutic Target

Purpose: Myeloma is a plasma cell malignancy characterized by the overproduction of immunoglobulin, and is therefore susceptible to therapies targeting protein homeostasis. We hypothesized that heat shock factor 1 (HSF1) was an attractive therapeutic target for myeloma due to its direct regulation of transcriptional programs implicated in both protein homeostasis and the oncogenic phenotype. Here, we interrogate HSF1 as a therapeutic target in myeloma using bioinformatic, genetic, and pharmacologic means.Experimental Design: To assess the clinical relevance of HSF1, we analyzed publicly available patient myeloma gene expression datasets. Validation of this novel target was conducted in in vitro experiments using shRNA or inhibitors of the HSF1 pathway in human myeloma cell lines and primary cells as well as in in vivo human myeloma xenograft models.Results: Expression of HSF1 and its target genes were associated with poorer myeloma patient survival. ShRNA-mediated knockdown or pharmacologic inhibition of the HSF1 pathway with a novel chemical probe, CCT251236, or with KRIBB11, led to caspase-mediated cell death that was associated with an increase in EIF2α phosphorylation, CHOP expression and a decrease in overall protein synthesis. Importantly, both CCT251236 and KRIBB11 induced cytotoxicity in human myeloma cell lines and patient-derived primary myeloma cells with a therapeutic window over normal cells. Pharmacologic inhibition induced tumor growth inhibition and was well-tolerated in a human myeloma xenograft murine model with evidence of pharmacodynamic biomarker modulation.Conclusions: Taken together, our studies demonstrate the dependence of myeloma cells on HSF1 for survival and support the clinical evaluation of pharmacologic inhibitors of the HSF1 pathway in myeloma. Clin Cancer Res; 24(10); 2395-407. ©2018 AACRSee related commentary by Parekh, p. 2237.

Oncogene-induced regulation of microRNA expression: Implications for cancer initiation, progression and therapy

A plethora of tumours have characteristic oncogenic mutations which are the main causes of malignant transformation, exerting their effects through multiple signalling pathways. Downstream of such pathways, microRNAs are small non-coding RNAs that negatively regulate gene expression, assisting or antagonizing oncogenic signalling. The differential expression of microRNAs in cancer is well-documented and is considered a fundamental aspect of tumourigenesis. While data mapping the interaction between oncogenic lesions and microRNAs are accruing, we provide particular cases of such interaction. Except for notable, well-studied examples of microRNAs regulated by oncogenes, we examine the effect of this relationship in regard to tumour initiation, progression, metastasis and ultimately, its implications for the development of new therapeutics.

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.

Prognostic role of HSF1 overexpression in solid tumors: a pooled analysis of 3,159 patients

Background and objective

HSF1 is reported to be overexpressed in various solid tumors and play a pivotal role in cancer progression. A meta-analysis was conducted to assess the potential prognostic role of HSF1 in patients with solid tumors.

Methods

An extensive electronic search of three databases was performed for relevant articles. The pooled hazard ratios (HRs) or odds ratios with their corresponding 95% CI were calculated with a random-effects model. Heterogeneity and publication bias analyses were also conducted.

Results

A total of 3,159 patients from 10 eligible studies were included into the analysis. The results showed that positive HSF1 expression was significantly correlated with poor overall survival in all tumors (HR=2.09; 95% CI: 1.62–2.70; P<0.001). Subgroup analysis revealed that there was a significant association between HSF1 overexpression and poor prognosis in esophageal squamous cell carcinoma (ESCC) (HR=1.83; 95% CI: 1.21–2.77; P=0.004), breast cancer (BC) (HR=1.52; 95% CI: 1.24–2.86; P<0.001), hepatocellular carcinoma (HR=3.02; 95% CI: 1.77–5.18; P<0.001), non-small-cell lung cancer (HR=2.19; 95% CI: 1.20–3.99; P=0.01), and pancreatic cancer (HR=2.58; 95% CI: 1.11–6.03; P=0.03) but not in osteosarcoma (HR=1.58; 95% CI: 0.47–5.35; P=0.46). In addition, HSF1 overexpression was significantly associated with some phenotypes of tumor aggressiveness including TNM stage, histological grade, lymph node metastasis, and vascular invasion.

Conclusion

HSF1 overexpression may prove to be an unfavorable prognostic biomarker for solid tumor patients.

Targeted Deletion of Hsf1, 2, and 4 Genes in Mice

Heat shock transcription factors (Hsfs) regulate transcription of heat shock proteins as well as other genes whose promoters contain heat shock elements (HSEs). There are at least five Hsfs in mammalian cells, Hsf1, Hsf2, Hsf3, Hsf4, and Hsfy (Wu, Annu Rev Cell Dev Biol 11:441-469, 1995; Morimoto, Genes Dev 12:3788-3796, 1998; Tessari et al., Mol Hum Repord 4:253-258, 2004; Fujimoto et al., Mol Biol Cell 21:106-116, 2010; Nakai et al., Mol Cell Biol 17:469-481, 1997; Sarge et al., Genes Dev 5:1902-1911, 1991). To understand the physiological roles of Hsf1, Hsf2, and Hsf4 in vivo, we generated knockout mouse lines for these factors (Zhang et al., J Cell Biochem 86:376-393, 2002; Wang et al., Genesis 36:48-61, 2003; Min et al., Genesis 40:205-217, 2004). Numbers of other laboratories have also generated Hsf1 (Xiao et al., EMBO J 18:5943-5952, 1999; Sugahara et al., Hear Res 182:88-96, 2003), Hsf2 (McMillan et al., Mol Cell Biol 22:8005-8014, 2002; Kallio et al., EMBO J 21:2591-2601, 2002), and Hsf4 (Fujimoto et al., EMBO J 23:4297-4306, 2004) knockout mouse models. In this chapter, we describe the design of the targeting vectors, the plasmids used, and the successful generation of mice lacking the individual genes. We also briefly describe what we have learned about the physiological functions of these genes in vivo.