Heat shock proteins in prostate cancer: from tumorigenesis to the clinic

Co-administration of "L-Lysine, Vitamin C, and Zinc" increased the antioxidant activity, decreased insulin resistance, and improved lipid profile in streptozotocin-induced diabetic rats

PURPOSE

We previously showed the beneficial effect of L-Lysine (Lys), a chemical chaperone, on reducing diabetic complications in diabetic rats and type 2 diabetic patients. Herein, we evaluated the effect of Lys co-administration with Vitamin C and Zinc (Lys+VC+Zn), in diabetic rats.

METHODS

The streptozotocin (50 mg/Kg) was injected into male adult Wistar rats to induce diabetes. Then, different groups of normal and diabetic rats were treated with Lys and Lys+VC+Zn for five months. So, there were 0.1 % Lys in the drinking water of both groups. The control groups received water alone. During the experiment, the body weight, and various parameters were determined in the blood, serum/plasma, and urine of the rats.

RESULTS

The determination of biochemical indexes confirmed diabetes induction and its complications in rats. Treatment with either Lys or Lys+VC+Zn resulted in reduced blood glucose and protein glycation (decreasing AGEs and HbA1c), increased insulin secretion, alleviated insulin resistance and HOMA-IR, improved lipid profile and HDL functionality (LCAT and PON1), enhanced antioxidant status (FRAP and AOPP), improved kidney function (decreased microalbuminuria, serum urea, and creatinine), and increased chaperone capacity (HSP70). Lys+VC+Zn showed better effects on these parameters than Lys alone.

CONCLUSIONS

The results of this study indicated that co-administration of Lys, a chemical chaperone, with two antioxidants (VC and Zn) potentiates its antidiabetic effects and prevent diabetic complications in rat model of diabetes.

Non-canonical androgen signaling pathways and implications in prostate cancer

Androgen signaling is a critical determinant of timely and proper development of all male organs including the prostate. Maturation of prostate and its neoplastic transformation is intricately associated with accurate androgen signaling. Ablation of androgen has therefore been the primary treatment mechanism of Prostate cancer (PCa) patients for several decades. Upon removal, the tumor recedes for a while, yet it reappears soon, in an androgen independent state, untreatable by current therapeutic regimens. Studies reveal that apart from the classical androgen signaling pathway known and targeted for almost a century, there exist several non-canonical pathways, with marked impact on classical androgen signaling and PCa growth. These include non-genomic signaling by androgens via alternate membrane GPCRs, signaling by non-androgens that ultimately impact the androgen signaling pathway, or an integration of non-genomic and genomic response as seen in case of protein kinase A activation. Accurate understanding of these various non-canonical androgen signaling pathways and their influence on the typical androgen signaling pathway can help design important interventions for PCa patients. This review analyses in detail the various non-classical androgen signaling pathways and their impact, if any, on classical mode of androgen action and PCa.

Heat Shock Proteins in Benign Prostatic Hyperplasia and Prostate Cancer

Two out of three diseases of the prostate gland affect aging men worldwide. Benign prostatic hyperplasia (BPH) is a noncancerous enlargement affecting millions of men. Prostate cancer (PCa) in turn is the second leading cause of cancer death. The factors influencing the occurrence of BPH and PCa are different; however, in the course of these two diseases, the overexpression of heat shock proteins is observed. Heat shock proteins (HSPs), chaperone proteins, are known to be one of the main proteins playing a role in maintaining cell homeostasis. HSPs take part in the process of the proper folding of newly formed proteins, and participate in the renaturation of damaged proteins. In addition, they are involved in the transport of specific proteins to the appropriate cell organelles and directing damaged proteins to proteasomes or lysosomes. Their function is to protect the proteins against degradation factors that are produced during cellular stress. HSPs are also involved in modulating the immune response and the process of apoptosis. One well-known factor affecting HSPs is the androgen receptor (AR)—a main player involved in the development of BPH and the progression of prostate cancer. HSPs play a cytoprotective role and determine the survival of cancer cells. These chaperones are often upregulated in malignancies and play an indispensable role in tumor progression. Therefore, HSPs are considered as one of the therapeutic targets in anti-cancer therapies. In this review article, we discuss the role of different HSPs in prostate diseases, and their potential as therapeutic targets.

A Review of Prostate Organogenesis and a Role for iPSC-Derived Prostate Organoids to Study Prostate Development and Disease

The prostate is vulnerable to two major age-associated diseases, cancer and benign enlargement, which account for significant morbidity and mortality for men across the globe. Prostate cancer is the most common cancer reported in men, with over 1.2 million new cases diagnosed and 350,000 deaths recorded annually worldwide. Benign prostatic hyperplasia (BPH), characterised by the continuous enlargement of the adult prostate, symptomatically afflicts around 50% of men worldwide. A better understanding of the biological processes underpinning these diseases is needed to generate new treatment approaches. Developmental studies of the prostate have shed some light on the processes essential for prostate organogenesis, with many of these up- or downregulated genes expressions also observed in prostate cancer and/or BPH progression. These insights into human disease have been inferred through comparative biological studies relying primarily on rodent models. However, directly observing mechanisms of human prostate development has been more challenging due to limitations in accessing human foetal material. Induced pluripotent stem cells (iPSCs) could provide a suitable alternative as they can mimic embryonic cells, and iPSC-derived prostate organoids present a significant opportunity to study early human prostate developmental processes. In this review, we discuss the current understanding of prostate development and its relevance to prostate-associated diseases. Additionally, we detail the potential of iPSC-derived prostate organoids for studying human prostate development and disease.

HSP90-specific nIR probe identifies aggressive prostate cancers: translation from preclinical models to a human phase I study

A noninvasive test to discriminate indolent prostate cancers from lethal ones would focus treatment where necessary while reducing over-treatment. We exploited the known activity of heat shock protein 90 (Hsp90) as a chaperone critical for the function of numerous oncogenic drivers, including the androgen receptor and its variants, to detect aggressive prostate cancer. We linked a near infrared fluorescing molecule to an HSP90 binding drug and demonstrated that this probe (designated HS196) was highly sensitive and specific for detecting implanted prostate cancer cell lines with greater uptake by more aggressive subtypes. In a phase I human study, systemically administered HS196 could be detected in malignant nodules within prostatectomy specimens. Single-cell RNA sequencing identified uptake of HS196 by malignant prostate epithelium from the peripheral zone (AMACR+ERG+EPCAM+ cells), including SYP+ neuroendocrine cells that are associated with therapeutic resistance and metastatic progression. A theranostic version of this molecule is under clinical testing.

Membrane Interactome of a Recombinant Fragment of Human Surfactant Protein D Reveals GRP78 as a Novel Binding Partner in PC3, a Metastatic Prostate Cancer Cell Line

Surfactant protein-D (SP-D), a member of the collectin family has been shown to induce apoptosis in cancer cells. SP-D is composed of an N-terminal collagen-like domain and a calcium-dependent carbohydrate recognition domain (CRD). Recently, we reported that a recombinant fragment of human SP-D (rfhSP-D), composed of homotrimeric CRD region, induced intrinsic apoptotic pathway in prostate cancer cells. Here, we analyzed the membrane interactome of rfhSP-D in an androgen-independent prostate cancer cell line, PC3, by high resolution mass spectrometry and identified 347 proteins. Computational analysis of PPI network of this interactome in the context of prostate cancer metastasis and apoptosis revealed Glucose Regulated Protein of 78 kDa (GRP78) as an important binding partner of rfhSP-D. Docking studies suggested that rfhSP-D (CRD) bound to the substrate-binding domain of glycosylated GRP78. This was further supported by the observations that human recombinant GRP78 interfered with the binding of rfhSP-D to anti-SP-D polyclonal antibodies; GRP78 also significantly inhibited the binding of recombinant full-length human SP-D with a monoclonal antibody specific to the CRD in a dose-dependent manner. We conclude that the interaction with rfhSP-D is likely to interfere with the pro-survival signaling of GRP78.

Hsp-27 and NF-κB pathway is associated with AR/AR-V7 expression in prostate cancer cells

In the present study, NF-κB inhibitor BAY 11-7082 and/or Hsp-27 inhibitor KRIBB-3 agents were used to investigate the molecular mechanisms mediating androgen receptor expression on prostate cancer cell lines. The decrease observed in androgen receptor and p65 expressions, particularly at 48 h, in parallel with the decrease in the phosphorylation of the p-IKK α/β and p-Hsp-27 proteins in the LNCaP cells, indicated that androgen receptor inactivation occurred after the inhibition of the NF-κB and Hsp-27. In 22Rv1 cells, androgen receptor variant-7 was also observed to be decreased in the combined dose of 48 h. The association of this decrease with the decrease in androgen receptor and p65 expressions is a supportive result for the role of NF-κB signaling in the formation of androgen receptor variant. In androgen receptor variant-7 siRNA treatment in 22Rv1 cell lines, decrease of expression of androgen receptor variant-7 as well as decrease of expression of androgen receptor and p65 were observed. The decrease statistically significant in androgen receptor and p65 expressions was even greater when siRNA treatment was followed with low dose and time (6 h) combined treatment after transfection. We also showed that increased Noxa and decreased Bcl-2 protein level, indicated that apoptotic induction after this combination. In conclusion, inhibition of NF-κB and Hsp-27 is also important, along with therapies for androgen receptor variant-7 inhibition.

Comprehensive transcriptomic analysis of heat shock proteins in the molecular subtypes of human breast cancer

BACKGROUND

Heat Shock Proteins (HSPs), a family of genes with key roles in proteostasis, have been extensively associated with cancer behaviour. However, the HSP family is quite large and many of its members have not been investigated in breast cancer (BRCA), particularly in relation with the current molecular BRCA classification. In this work, we performed a comprehensive transcriptomic study of the HSP gene family in BRCA patients from both The Cancer Genome Atlas (TCGA) and the Molecular Taxonomy of Breast Cancer International Consortium (METABRIC) cohorts discriminating the BRCA intrinsic molecular subtypes.

METHODS

We examined gene expression levels of 1097 BRCA tissue samples retrieved from TCGA and 1981 samples of METABRIC, focusing mainly on the HSP family (95 genes). Data were stratified according to the PAM50 gene expression (Luminal A, Luminal B, HER2, Basal, and Normal-like). Transcriptomic analyses include several statistical approaches: differential gene expression, hierarchical clustering and survival analysis.

RESULTS

Of the 20,531 analysed genes we found that in BRCA almost 30% presented deregulated expression (19% upregulated and 10% downregulated), while of the HSP family 25% appeared deregulated (14% upregulated and 11% downregulated) (|fold change| > 2 comparing BRCA with normal breast tissues). The study revealed the existence of shared HSP genes deregulated in all subtypes of BRCA while other HSPs were deregulated in specific subtypes. Many members of the Chaperonin subfamily were found upregulated while three members (BBS10, BBS12 and CCTB6) were found downregulated. HSPC subfamily had moderate increments of transcripts levels. Various genes of the HSP70 subfamily were upregulated; meanwhile, HSPA12A and HSPA12B appeared strongly downregulated. The strongest downregulation was observed in several HSPB members except for HSPB1. DNAJ members showed heterogeneous expression pattern. We found that 23 HSP genes correlated with overall survival and three HSP-based transcriptional profiles with impact on disease outcome were recognized.

CONCLUSIONS

We identified shared and specific HSP genes deregulated in BRCA subtypes. This study allowed the recognition of HSP genes not previously associated with BRCA and/or any cancer type, and the identification of three clinically relevant clusters based on HSPs expression patterns with influence on overall survival.

Recombinant heat shock protein 27 (HSP27/HSPB1) protects against cadmium-induced oxidative stress and toxicity in human cervical cancer cells

Cadmium (Cd) is a carcinogen with several well-described toxicological effects in humans, but its molecular mechanisms are still not fully understood. Overexpression of heat shock protein 27 (HSP27/HSPB1)-a multifunctional protein chaperone-has been shown to protect cells from oxidative damage and apoptosis triggered by Cd exposure. The aims of this work were to investigate the potential use of extracellular recombinant HSP27 to prevent/counteract Cd-induced cellular toxicity and to evaluate if peroxynitrite was involved in the development of Cd-induced toxicity. Here, we report that the harmful effects of Cd correlated with changes in oxidative stress markers: upregulation of reactive oxygen species, reduction in nitric oxide (NO) bioavailability, increment in lipid peroxidation, peroxynitrite (PN), and protein nitration; intracellular HSP27 was reduced. Treatments with Cd (100 μM) for 24 h or with the peroxynitrite donor, SIN-1, decreased HSP27 levels (~50%), suggesting that PN formation is responsible for the reduction of HSP27. Pre-treatments of the cells either with Nω-nitro-L-arginine methyl ester hydrochloride (L-NAME) (a pharmacological inhibitor of NO synthase) or with recombinant HSP27 (rHSP27) attenuated the disruption of the cellular metabolism induced by Cd, increasing in a 55 and 52%, respectively, the cell viability measured by CCK-8. Cd induced necrotic cell death pathways, although apoptosis was also activated; pre-treatment with L-NAME or rHSP27 mitigated cell death. Our findings show for the first time a direct relationship between Cd-induced toxicity and PN production and a role for rHSP27 as a potential therapeutic agent that may counteract Cd toxicity.

Green Tea Catechins for Prostate Cancer Prevention: Present Achievements and Future Challenges

Green tea catechins (GTCs) are a family of chemically related compounds usually classified as antioxidant molecules. Epidemiological evidences, supported by interventional studies, highlighted a more than promising role for GTCs in human prostate cancer (PCa) chemoprevention. In the last decades, many efforts have been made to gain new insights into the mechanism of action of GTCs. Now it is clear that GTCs' anticancer action can no longer be simplistically limited to their direct antioxidant/pro-oxidant properties. Recent contributions to the advancement of knowledge in this field have shown that GTCs specifically interact with cellular targets, including cell surface receptors, lipid rafts, and endoplasmic reticulum, modulate gene expression through direct effect on transcription factors or indirect epigenetic mechanisms, and interfere with intracellular proteostasis at various levels. Many of the effects observed in vitro are dose and cell context dependent and take place at concentrations that cannot be achieved in vivo. Poor intestinal absorption together with an extensive systemic and enteric metabolism influence GTCs' bioavailability through still poorly understood mechanisms. Recent efforts to develop delivery systems that increase GTCs' overall bioavailability, by means of biopolymeric nanoparticles, represent the main way to translate preclinical results in a real clinical scenario for PCa chemoprevention.

Heat shock protein 27 regulates human prostate cancer cell motility and metastatic progression

Prostate cancer (PCa) is the most common form of cancer in American men. Mortality from PCa is caused by the movement of cancer cells from the primary organ to form metastatic tumors at distant sites. Heat shock protein 27 (HSP27) is known to increase human PCa cell invasion and its overexpression is associated with metastatic disease. The role of HSP27 in driving PCa cell movement from the prostate to distant metastatic sites is unknown. Increased HSP27 expression increased metastasis as well as primary tumor mass. In vitro studies further examined the mechanism of HSP27-induced metastatic behavior. HSP27 did not affect cell detachment, adhesion, or migration, but did increase cell invasion. Cell invasion was dependent upon matrix metalloproteinase 2 (MMP-2), whose expression was increased by HSP27. In vivo, HSP27 induced commensurate changes in MMP-2 expression in tumors. These findings demonstrate that HSP27 drives metastatic spread of cancer cells from the prostate to distant sites, does so across a continuum of expression levels, and identifies HSP27-driven increases in MMP-2 expression as functionally relevant. These findings add to prior studies demonstrating that HSP27 increases PCa cell motility, growth and survival. Together, they demonstrate that HSP27 plays an important role in PCa progression.

NSK-01105, a novel sorafenib derivative, inhibits human prostate tumor growth via suppression of VEGFR2/EGFR-mediated angiogenesis

The purpose of this study is to investigate the anti-angiogenic activities of NSK-01105, a novel sorafenib derivative, in in vitro, ex vivo and in vivo models, and explore the potential mechanisms. NSK-01105 significantly inhibited vascular endothelial growth factor (VEGF)-induced migration and tube formation of human umbilical vein endothelial cells at non-cytotoxic concentrations as shown by wound-healing, transwell migration and endothelial cell tube formation assays, respectively. Cell viability and invasion of LNCaP and PC-3 cells were significantly inhibited by cytotoxicity assay and matrigel invasion assay. Furthermore, NSK-01105 also inhibited ex vivo angiogenesis in matrigel plug assay. Western blot analysis showed that NSK-01105 down-regulated VEGF-induced phosphorylation of VEGF receptor 2 (VEGFR2) and the activation of epidermal growth factor receptor (EGFR). Tumor volumes were significantly reduced by NSK-01105 at 60 mg/kg/day in both xenograft models. Immunohistochemical staining demonstrated a close association between inhibition of tumor growth and neovascularization. Collectively, our results suggest a role of NSK-01105 in treatment for human prostate tumors, and one of the potential mechanisms may be attributed to anti-angiogenic activities.

Proteomic signatures of extracellular vesicles secreted by nonmineralizing and mineralizing human osteoblasts and stimulation of tumor cell growth

Beyond forming bone, osteoblasts play pivotal roles in various biologic processes, including hematopoiesis and bone metastasis. Extracellular vesicles (EVs) have been implicated in intercellular communication via transfer of proteins and nucleic acids between cells. We focused on the proteomic characterization of nonmineralizing (NMOBs) and mineralizing (MOBs) human osteoblast (SV-HFOs) EVs and investigated their effect on human prostate cancer (PC3) cells by microscopic, proteomic, and gene expression analyses. Proteomic analysis showed that 97% of the proteins were shared among NMOB and MOB EVs, and 30% were novel osteoblast-specific EV proteins. Label-free quantification demonstrated mineralization stage-dependent 5-fold enrichment of 59 and 451 EV proteins in NMOBs and MOBs, respectively. Interestingly, bioinformatic analyses of the osteoblast EV proteomes and EV-regulated prostate cancer gene expression profiles showed that they converged on pathways involved in cell survival and growth. This was verified by in vitro proliferation assays where osteoblast EV uptake led to 2-fold increase in PC3 cell growth compared to cell-free culture medium-derived vesicle controls. Our findings elucidate the mineralization stage-specific protein content of osteoblast-secreted EVs, show a novel way by which osteoblasts communicate with prostate cancer, and open up innovative avenues for therapeutic intervention.

Immunohistochemical expression of heat shock proteins, p63 and androgen receptor in benign prostatic hyperplasia and prostatic carcinoma in the dog

This study compared heat shock proteins Hsp60, Hsp72 and Hsp73, along with p63 and androgen receptor (AR) immunoexpression between 16 cases of benign prostatic hyperplasia (BPH) and 11 prostatic carcinomas (PCa) in dogs. The proportion of Hsp60-positive cells was higher in PCa compared with BPH (P = 0.033), whereas the frequency and intensity of Hsp73 immunostaining did not differ significantly between the two groups. Hsp72-immunostained nuclei formed a discontinuous layer along the basement membrane in BPH, whereas cells in this layer in PCa were negative or weakly positive. Hsp72 nuclear score showed significant positive associations with both p63 (P = 0.016) and AR (P = 0.009) scores. Double immunofluorescence revealed Hsp72-p63 and Hsp72-AR co-expressions in basal cell nuclei. Aberrant cytoplasmic p63 immunolabelling was observed in 3 of 11 PCa cases. These results suggest a role of the combined expression of Hsp72, p63 and AR in basal epithelial cells in canine BPH and PCa.

HspB1, HspB5 and HspB4 in Human Cancers: Potent Oncogenic Role of Some of Their Client Proteins

Human small heat shock proteins are molecular chaperones that regulate fundamental cellular processes in normal unstressed cells as well as in many cancer cells where they are over-expressed. These proteins are characterized by cell physiology dependent changes in their oligomerization and phosphorylation status. These structural changes allow them to interact with many different client proteins that subsequently display modified activity and/or half-life. Nowdays, the protein interactomes of small Hsps are under intense investigations and will represent, when completed, key parameters to elaborate therapeutic strategies aimed at modulating the functions of these chaperones. Here, we have analyzed the potential pro-cancerous roles of several client proteins that have been described so far to interact with HspB1 (Hsp27) and its close members HspB5 (αB-crystallin) and HspB4 (αA-crystallin).

Targeting the heat shock response in cancer: tipping the balance in transformed cells

The elucidation of the heat shock response (HSR) as a mediator of cellular stress has created a framework for understanding how these processes may promote tumorigenesis. Furthermore, the identification of specific components of the HSR and how they are co-opted by cancer cells has led to the discovery of new therapeutic targets. A wide range of small molecule inhibitors of the HSR are in various stages of development for clinical application in patients with cancer. The introduction of these novel small molecule inhibitors offers the opportunity for synergy with existing therapies and the potential for highly targeted treatments.

Mild hyperthermia enhances the expression and induces oscillations in the Dicer protein

PURPOSE

To investigate whether mild heat stress at 39.5°C altered Dicer protein and miRNA expression patterns in several cell types.

METHODS

Multiple human and mouse cell types were cultured during the course of 9 h at temperatures from 37°C to 39.5°C. Dicer mRNA levels and microRNAs were quantified by TaqMan RT-qPCR assays and Dicer protein by western blotting.

RESULTS

Dicer protein was substantially elevated on western analysis in response to heat stress at 39.5°C in the absence of significant changes in Dicer mRNA by RT-qPCR.

CONCLUSIONS

Heat-induced regulation of Dicer expression occurs primarily post- transcriptionally, and the expression levels of Dicer protein are increased and often oscillate in response to fever-range hyperthermia in multiple mouse and human cells. Our studies suggest a potential role for Dicer and microRNAs in the response to mild thermal stress. Additional studies on the mechanisms involved in the stress-induced oscillations of Dicer protein and microRNAs will be of interest.

Stress-response protein RBM3 attenuates the stem-like properties of prostate cancer cells by interfering with CD44 variant splicing

Stress-response pathways play an important role in cancer. The cold-inducible RNA-binding protein RBM3 is upregulated in several types of cancer, including prostate cancer, but its pathogenic contributions are undetermined. RBM3 is expressed at low basal levels in human fetal prostate or in CD133(+) prostate epithelial cells (PrEC), compared with the adult prostate or CD133-PrEC, and RBM3 is downregulated in cells cultured in soft agar or exposed to stress. Notably, RBM3 overexpression in prostate cancer cells attenuated their stem cell-like properties in vitro as well as their tumorigenic potential in vivo. Interestingly, either overexpressing RBM3 or culturing cells at 32°C suppressed RNA splicing of the CD44 variant v8-v10 and increased expression of the standard CD44 (CD44s) isoform. Conversely, silencing RBM3 or culturing cells in soft agar (under conditions that enrich for stem cell-like cells) increased the ratio of CD44v8-v10 to CD44s mRNA. Mechanistic investigations showed that elevating CD44v8-v10 interfered with MMP9-mediated cleavage of CD44s and suppressed expression of cyclin D1, whereas siRNA-mediated silencing of CD44v8-v10 impaired the ability of prostate cancer cells to form colonies in soft agar. Together, these findings suggested that RBM3 contributed to stem cell-like character in prostate cancer by inhibiting CD44v8-v10 splicing. Our work uncovers a hitherto unappreciated role of RBM3 in linking stress-regulated RNA splicing to tumorigenesis, with potential prognostic and therapeutic implications in prostate cancer.

Proteogenomic analysis of human colon carcinoma cell lines LIM1215, LIM1899, and LIM2405

As part of the genome-wide and chromosome-centric human proteomic project (C-HPP), we have integrated shotgun proteomics approach and a genome-wide transcriptomic approach (RNA-Seq) of a set of human colon cancer cell lines (LIM1215, LIM1899 and LIM2405) that were selected to represent a wide range of pathological states of colorectal cancer. The combination of a standard proteomics approach (1D-gel electrophoresis coupled to LC/ion trap mass spectrometry) and RNA-Seq allowed us to exploit the greater depth of the transcriptomics measurement (∼ 9800 transcripts per cell line) versus the protein observations (∼ 1900 protein identifications per cell line). Conversely, the proteomics data were helpful in identifying both cancer associated proteins with differential expression patterns as well as protein networks and pathways which appear to be deregulated in these cell lines. Examples of potential markers include mortalin, nucleophosmin, ezrin, LASP1, alpha and beta forms of spectrin, exportin, the carcinoembryonic antigen family, EGFR and MET. Interaction analyses identified the large intermediate filament family, the protein folding network and adapter proteins in focal adhesion networks, which included the CDC42 and RHOA signaling pathways that may have potential for identifying phenotypic states representing poorly and moderately differentiated states of CRC, with or without metastases.

Heat shock proteins and heat shock factor 1 in carcinogenesis and tumor development: an update

Heat shock proteins (HSP) are a subset of the molecular chaperones, best known for their rapid and abundant induction by stress. HSP genes are activated at the transcriptional level by heat shock transcription factor 1 (HSF1). During the progression of many types of cancer, this heat shock transcriptional regulon becomes co-opted by mechanisms that are currently unclear, although evidently triggered in the emerging tumor cell. Concerted activation of HSF1 and the accumulation of HSPs then participate in many of the traits that permit the malignant phenotype. Thus, cancers of many histologies exhibit activated HSF1 and increased HSP levels that may help to deter tumor suppression and evade therapy in the clinic. We review here the extensive work that has been carried out and is still in progress aimed at (1) understanding the oncogenic mechanisms by which HSP genes are switched on, (2) determining the roles of HSF1/HSP in malignant transformation and (3) discovering approaches to therapy based on disrupting the influence of the HSF1-controlled transcriptome in cancer.

Hyperthermia stimulates HIV-1 replication

HIV-infected individuals may experience fever episodes. Fever is an elevation of the body temperature accompanied by inflammation. It is usually beneficial for the host through enhancement of immunological defenses. In cultures, transient non-physiological heat shock (42–45°C) and Heat Shock Proteins (HSPs) modulate HIV-1 replication, through poorly defined mechanisms. The effect of physiological hyperthermia (38–40°C) on HIV-1 infection has not been extensively investigated. Here, we show that culturing primary CD4+ T lymphocytes and cell lines at a fever-like temperature (39.5°C) increased the efficiency of HIV-1 replication by 2 to 7 fold. Hyperthermia did not facilitate viral entry nor reverse transcription, but increased Tat transactivation of the LTR viral promoter. Hyperthermia also boosted HIV-1 reactivation in a model of latently-infected cells. By imaging HIV-1 transcription, we further show that Hsp90 co-localized with actively transcribing provirus, and this phenomenon was enhanced at 39.5°C. The Hsp90 inhibitor 17-AAG abrogated the increase of HIV-1 replication in hyperthermic cells. Altogether, our results indicate that fever may directly stimulate HIV-1 replication, in a process involving Hsp90 and facilitation of Tat-mediated LTR activity.

Fever is a complex reaction triggered in response to pathogen infection. It induces diverse effects on the human body and especially on the immune system. The functions of immune cells are positively affected by fever, helping them to fight infection. Fever consists in a physiological elevation of temperature and in inflammation. While the role of inflammatory molecules on HIV-1 replication has been widely studied, little is known about the direct effect of temperature on viral replication. Here, we report that hyperthermia (39.5°C) boosts HIV-1 replication in CD4+ T cells. In single-cycle infection experiments, hyperthermia increased HIV-1 infection up to 7-fold. This effect was mediated in part by an increased activation of the HIV-1 promoter by the viral protein Tat. Our results also indicate that hyperthermia may help HIV-1 to reactivate from latency. We also show that the Heat Shock Protein Hsp90, which levels are increased at 39.5°C, mediates in a large part the positive effect of hyperthermia on HIV-1 infection. Our work suggests that in HIV-1-infected patients, fever episodes may facilitate viral replication.

Old and new facts about hyperthermia-induced modulations of the immune system

Hyperthermia (HT) is a potent sensitiser for radiotherapy (RT) and chemotherapy (CT) and has been proven to modulate directly or indirectly cells of the innate and adaptive immune system. We will focus in this article on how anti-tumour immunity can be induced by HT. In contrast to some in vitro assays, in vivo examinations showed that natural killer cells and phagocytes like granulocytes are directly activated against the tumour by HT. Since heat also activates dendritic cells (DCs), HT should be combined with further death stimuli (RT, CT or immune therapy) to allocate tumour antigen, derived from, for example, necrotic tumour cells, for uptake by DCs. We will outline that induction of immunogenic tumour cells and direct tumour cell killing by HT in combination with other therapies contributes to immune activation against the tumour. Studies will be presented showing that non-beneficial effects of HT on immune cells are mostly timely restricted. A special focus is set on immune activation mediated by extracellular present heat shock proteins (HSPs) carrying tumour antigens and further danger signals released by dying tumour cells. Local HT treatment in addition to further stress stimuli exerts abscopal effects and might be considered as in situ tumour vaccination. An increased natural killer (NK) cell activity, lymphocyte infiltration and HSP-mediated induction of immunogenic tumour cells have been observed in patients. Treatments with the addition of HT therefore can be considered as a personalised cancer treatment approach by specifically activating the immune system against the individual unique tumour.

Identification of differentially expressed proteins in curcumin-treated prostate cancer cell lines

Due to high prevalence and slow progression of prostate cancer, primary prevention appears to be attractive strategy for its eradication. During the last decade, curcumin (diferuloylmethane), a natural compound from the root of turmeric (Curcuma longa), was described as a potent chemopreventive agent. Curcumin exhibits anti-inflammatory, anticarcinogenic, antiproliferative, antiangiogenic, and antioxidant properties in various cancer cell models. This study was designed to identify proteins involved in the anticancer activity of curcumin in androgen-dependent (22Rv1) and -independent (PC-3) human prostate cancer cell lines using two-dimensional difference in gel electrophoresis (2D-DIGE). Out of 425 differentially expressed spots, we describe here the MALDI-TOF-MS analysis of 192 spots of interest, selected by their expression profile. This approach allowed the identification of 60 differentially expressed proteins (32 in 22Rv1 cells and 47 in PC-3 cells). Nineteen proteins are regulated in both cell lines. Further bioinformatic analysis shows that proteins modulated by curcumin are implicated in protein folding (such as heat-shock protein PPP2R1A; RNA splicing proteins RBM17, DDX39; cell death proteins HMGB1 and NPM1; proteins involved in androgen receptor signaling, NPM1 and FKBP4/FKBP52), and that this compound could have an impact on miR-141, miR-152, and miR-183 expression. Taken together, these data support the hypothesis that curcumin is an interesting chemopreventive agent as it modulates the expression of proteins that potentially contribute to prostate carcinogenesis.

Changing the energy habitat of the cancer cell in order to impact therapeutic resistance

Somatic cellular evolution is becoming a popular biological explanation for the common rapid development of resistance to almost every form of cancer therapy and against almost every form of advanced human solid tumors. As a result of the historical power of evolution within nature, this common biological interpretation of the failure of cancer therapy is leading to a growing despair for many investigators and a stronger turn toward prevention through lifestyle changes. The absolute explosion of molecular scientific discoveries since 1983, in the reductionist identification of specific cancer therapeutic targets, has failed to deliver the impact in the clinic that many of us would have hoped would have resulted by this time. Personalized molecular medicine may help us reclassify appropriate therapeutic subgroups, but will it significantly impact the overall specific survival times for all of the cancers combined within the organ type for the entire population? How might we approach this therapeutic dilemma by utilizing new therapeutic insights designed on proven principles of evolution? In other words, can we fight the development of therapeutic resistance in cancer cells by turning established aspects of evolution against the survival of cancer cells within the individual patient? Here we review the concepts of changing the heat habitat and microenvironment of the cancer cell to alter the higher order organization and function of DNA. We have proposed that heat may be a major factor in determining the lasting therapeutic effect on many types of far advanced metastatic tumors.

Implication of heat shock factors in tumorigenesis: therapeutical potential

Heat Shock Factors (HSF) form a family of transcription factors (four in mammals) which were named according to the discovery of their activation by a heat shock. HSFs trigger the expression of genes encoding Heat Shock Proteins (HSPs) that function as molecular chaperones, contributing to establish a cytoprotective state to various proteotoxic stresses and in pathological conditions. Increasing evidence indicates that this ancient transcriptional protective program acts genome-widely and performs unexpected functions in the absence of experimentally defined stress. Indeed, HSFs are able to re-shape cellular pathways controlling longevity, growth, metabolism and development. The most well studied HSF, HSF1, has been found at elevated levels in tumors with high metastatic potential and is associated with poor prognosis. This is partly explained by the above-mentioned cytoprotective (HSP-dependent) function that may enable cancer cells to adapt to the initial oncogenic stress and to support malignant transformation. Nevertheless, HSF1 operates as major multifaceted enhancers of tumorigenesis through, not only the induction of classical heat shock genes, but also of “non-classical” targets. Indeed, in cancer cells, HSF1 regulates genes involved in core cellular functions including proliferation, survival, migration, protein synthesis, signal transduction, and glucose metabolism, making HSF1 a very attractive target in cancer therapy. In this review, we describe the different physiological roles of HSFs as well as the recent discoveries in term of non-cogenic potential of these HSFs, more specifically associated to the activation of “non-classical” HSF target genes. We also present an update on the compounds with potent HSF1-modulating activity of potential interest as anti-cancer therapeutic agents.