Role Of Heat Shock Proteins Research Articles

Radiofrequency ablation: mechanisms and clinical applications.

Radiofrequency ablation (RFA), a form of thermal ablation, employs localized heat to induce protein denaturation in tissue cells, resulting in cell death. It has emerged as a viable treatment option for patients who are ineligible for surgery in various diseases, particularly liver cancer and other tumor-related conditions. In addition to directly eliminating tumor cells, RFA also induces alterations in the infiltrating cells within the tumor microenvironment (TME), which can significantly impact treatment outcomes. Moreover, incomplete RFA (iRFA) may lead to tumor recurrence and metastasis. The current challenge is to enhance the efficacy of RFA by elucidating its underlying mechanisms. This review discusses the clinical applications of RFA in treating various diseases and the mechanisms that contribute to the survival and invasion of tumor cells following iRFA, including the roles of heat shock proteins, hypoxia, and autophagy. Additionally, we analyze‌ the changes occurring in infiltrating cells within the TME after iRFA. Finally, we provide a comprehensive summary of clinical trials involving RFA in conjunction with other treatment modalities in the field of cancer therapy, aiming to offer novel insights and references for improving the effectiveness of RFA.

Targeting HSP90 for Cancer Therapy: Current Progress and Emerging Prospects.

Heat shock protein 90 (HSP90), a highly conserved member of the heat shock protein family, regulates various proteins and signaling pathways involved in cancer, making it a promising target for cancer therapy. Traditional HSP90 inhibitors have demonstrated significant antitumor potential in preclinical trials, with over 20 compounds advancing to clinical trials and showing promising results. However, the limited clinical efficacy and shared toxicity of these inhibitors restrict their further clinical use. Encouragingly, developing novel inhibitors using conventional medicinal chemistry approaches─such as selective inhibitors, dual inhibitors, protein-protein interaction inhibitors, and proteolysis-targeting chimeras─is expected to address these challenges. Notably, the selective inhibitor TAS-116 has already been successfully marketed. In this Perspective, we summarize the structure, biological functions, and roles of HSP90 in cancer, analyze the clinical status of HSP90 inhibitors, and highlight the latest advancements in novel strategies, offering insights into their future development.

Role of Heat-Shock Proteins in the Determination of Postmortem Metabolism and Meat Quality Development of DFD Meat.

This research explored the potential role of various heat-shock proteins (HSPs) in the determination of postmortem metabolism and the development of meat quality of normal, atypical DFD, and typical DFD beef. Beef longissimus thoracis muscle samples were classified into normal, atypical DFD, and typical DFD beef. The HSP27, HSP70, and HSP90 levels, meat quality parameters, and glycolytic metabolites were tested. The results showed that color coordinates (L*, a*, and b*), glycogen, and lactate contents were lower, whereas water-holding capacity was higher in the typical DFD beef than in the normal and atypical DFD beef (p < 0.05). The expression of HSP27 on day 1 was higher in atypical DFD beef. However, expressions of HSP70 on days 1 and 3 were higher in typical DFD, while the expression of HSP90 on day 1 was higher in atypical and typical DFD compared to the normal beef (p < 0.05). Interestingly, the expression of HSP27 was positively correlated with shear force readings. HSP70 and HSP90 presented a direct correlation with pH and water-holding capacity and an indirect correlation with a* and b*, glycogen and lactate contents (p < 0.05). The study concluded that the heat-shock proteins could influence the formation of DFD beef possibly by regulating the development of postmortem metabolism and meat quality traits.

The role of heat shock proteins in HIV-1 pathogenesis: a systematic review investigating HSPs-HIV-1 correlations and interactions.

The human immunodeficiency virus (HIV) pandemic is a global health emergency. Studies suggest a connection between heat shock proteins (HSPs) and HIV-1 infection pathogenesis. This systematic review aims to summarize HSPs' role in HIV-1 infection pathogenesis. A systematic literature search was undertaken across the National Library of Medicine (MEDLINE-PubMed), Science Direct, Web of Science, Scopus, SpringerLink, Sage, ProQuest, and Google Scholar databases, using related keywords to synthesize the HSPs' role in HIV-1 infection pathogenesis. This literature review was conducted according to Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, and the protocol was registered in the Open Science Framework (OSF) database under DOI 10.17605/OSF.IO/VK3DJ. A database search revealed 3,332 articles, with 14 in vitro studies analysing the interaction between HSPs and HIV-1 across different cell types. HSPs are involved in HIV-1 infection through direct interactions and indirect responses to cellular stress, including HSP40, HSP70, HSPBP1, and HSP90. The study explores HSP interactions at various stages of the viral life cycle, including entry, uncoating, replication, transmission, and latency reactivation. HSPs are crucial for the HIV lifecycle and immune response, offering the potential for new therapeutic strategies. Further research is needed to understand the clinical significance and target potential.

Inter-subspecies diversity of maize to drought stress with physio-biochemical, enzymatic and molecular responses.

Drought is the most significant factor limiting maize production, given that maize is a crop with a high water demand. Therefore, studies investigating the mechanisms underlying the drought tolerance of maize are of great importance. There are no studies comparing drought tolerance among economically important subspecies of maize. This study aimed to reveal the differences between the physio-biochemical, enzymatic, and molecular mechanisms of drought tolerance in dent (Zea mays indentata), popcorn (Zea mays everta), and sugar (Zea mays saccharata) maize under control (no-stress), moderate, and severe drought stress. Three distinct irrigation regimes were employed to assess the impact of varying levels of drought stress on maize plants at the V14 growth stage. These included normal irrigation (80% field capacity), moderate drought (50% field capacity), and severe drought (30% field capacity). All plants were grown under controlled conditions. The following parameters were analyzed: leaf relative water content (RWC), loss of turgidity (LOT), proline (PRO) and soluble protein (SPR) contents, membrane durability index (MDI), malondialdehyde (MDA), and hydrogen peroxide (H2O2) content, the antioxidant enzyme activities of superoxide dismutase (SOD), ascorbate peroxidase (APX), and catalase (CAT). Additionally, the expression of heat shock proteins (HSPs) was examined at the transcriptional and translational levels. The effects of severe drought were more pronounced in sugar maize, which had a relatively high loss of RWC and turgor, membrane damage, enzyme activities, and HSP90 gene expression. Dent maize, which is capable of maintaining its RWC and turgor in both moderate and severe droughts, and employs its defense mechanism effectively by maintaining antioxidant enzyme activities at a certain level despite less MDA and H2O2 accumulation, exhibited relatively high drought tolerance. Despite the high levels of MDA and H2O2 in popcorn maize, the up-regulation of antioxidant enzyme activities and HSP70 gene and protein expression indicated that the drought coping mechanism is activated. In particular, the positive correlation of HSP70 with PRO and HSP90 with enzyme activities is a significant result for studies examining the relationships between HSPs and other stress response systems. The discrepancies between the transcriptional and translational findings provide an opportunity for more comprehensive investigations into the role of HSPs in stress conditions.

Association analysis of HSP90AA1 polymorphism with thermotolerance in tropically adapted Indian crossbred cattle.

Raising cattle is a lucrative business that operates globally but is confronted by many obstacles, such as thermal stress, which results in substantial monetary losses. A vital role of heat shock proteins (HSPs) is to protect cells from cellular damage. HSP90 is a highly prevalent, extremely adaptable gene linked to physiological resilience in thermal stress. This study aimed to find genetic polymorphisms of the HSP90AA1 gene in Karan Fries cattle and explore their relationship to thermal tolerance and production traits. One SNP (g.3292A > C) was found in the Intron 8 and three SNPs loci (g.4776A > G, g.5218T > C and g.5224A > C) were found in the exon 11 of 100 multiparous Karan Fries cattle. The association study demonstrated that the SNP1-g.3292A > C was significantly (P < 0.01) linked to the variables respiratory rate (RR), heat tolerance coefficient (HTC) and total milk yield (TMY (kg)) attributes. There was no significant correlation identified between any of the other SNP sites (SNP2-g.4776A > G; SNP3-g.5218T > C; SNP4-g.5224A > C) with the heat tolerance and production attributes in Karan Fries cattle. Haploview 4.2 and SHEsis software programs were used to analyse pair linkage disequilibrium and construct haplotypes for HSP90AA1. Association studies indicated that the Hap3 (CATA) was beneficial for heat tolerance breeding in Karan Fries cattle. In conclusion, genetic polymorphisms and haplotypes in the HSP90AA1 were associated with thermal endurance attributes. This relationship can be utilized as a beneficial SNP or Hap marker for genetic heat resistance selection in cow breeding platforms.

The Protective Role of Heat Shock Proteins against Stresses in Animal Breeding.

Heat shock proteins (HSPs) play an important role in all living organisms under stress conditions by acting as molecular chaperones. The expression of different HSPs during stress varies depending on their protective functions and anti-apoptotic activities. The application of HSPs improves the efficiency and decreases the economic cost of animal breeding. By upregulating the expression of HSPs, feed supplements can improve stress tolerance in farm animals. In addition, high expression of HSPs is often a feature of tumor cells, and inhibiting the expression of HSPs is a promising novel method for killing these cells and treating cancers. In the present review, the findings of previous research on the application of HSPs in animal breeding and veterinary medicine are summarized, and the knowledge of the actions of HSPs in animals is briefly discussed.

Structural biology of HER2/ERBB2 dimerization: mechanistic insights and differential roles in healthy versus cancerous cells

Aim: Present study was done to understand the dimerization of HER2/ERBB2 in normal and cancer cells using in-silico study. Methods: Pathway analysis was done using Reactome. Structure of HER2/ERBB2 protein was obtained from PDB database, and using Schrödinger software protein structure was analysed and dimerization was done. Results: In normal cells, HER2/ERBB2 is present at low levels and forms a stable complex with HSP90 (heat shock protein 90), CDC37 (cell division cycle 37), and ERBIN (an adaptor protein of the HER2/ERBB2 receptor). HER2/ERBB2 lacks a ligand-binding site, so it cannot bind ligands to activate HER2/ERBB2 signaling directly. Instead, it heterodimerizes with other EGFR family members, using their ligand-binding sites to activate cell proliferation signaling cascades. In cancer, overexpression of HER2/ERBB2 leads to ligand-independent activation of signaling through dimerization. During this process, HER2/ERBB2 dissociates from the HSP90 complex. Normally, HSP90 helps to correct misfolded and aggregated proteins, but it fails to correct mutated HER2/ERBB2 in cancer cells. Conclusions: This discussion focuses on the structural changes that HER2/ERBB2 undergoes, particularly in the form of homodimers, under normal and cancerous conditions. This analysis highlights the mutated state of HER2/ERBB2 and the role of HSP90 in this context. Notably, a single-point mutation outside a protein’s active site can significantly alter its structure. This is a critical consideration in drug discovery, underscoring the need to evaluate the entire protein conformation during simulations.

The Role of Heat Shock Protein 70 (HSP70) in the Pathogenesis of Ocular Diseases-Current Literature Review.

Heat shock proteins (HSPs) have been attracting the attention of researchers for many years. HSPs are a family of ubiquitous, well-characterised proteins that are generally regarded as protective multifunctional molecules that are expressed in response to different types of cell stress. Their activity in many organs has been reported, including the heart, brain, and retina. By acting as chaperone proteins, HSPs help to refold denatured proteins. Moreover, HSPs elicit inhibitory activity in apoptotic pathways and inflammation. Heat shock proteins were originally classified into several subfamilies, including the HSP70 family. The aim of this paper is to systematise information from the available literature about the presence of HSP70 in the human eye and its role in the pathogenesis of ocular diseases. HSP70 has been identified in the cornea, lens, and retina of a normal eye. The increased expression and synthesis of HSP70 induced by cell stress has also been demonstrated in eyes with pathologies such as glaucoma, eye cancers, cataracts, scarring of the cornea, ocular toxpoplasmosis, PEX, AMD, RPE, and diabetic retinopathy. Most of the studies cited in this paper confirm the protective role of HSP70. However, little is known about these molecules in the human eye and their role in the pathogenesis of eye diseases. Therefore, understanding the role of HSP70 in the pathophysiology of injuries to the cornea, lens, and retina is essential for the development of new therapies aimed at limiting and/or reversing the processes that cause damage to the eye.

Tumor Dormancy and Reactivation: The Role of Heat Shock Proteins.

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

Are Heat Shock Proteins Important in Low-Temperature-Stressed Plants? A Minireview

Heat shock proteins (HSPs) are mainly known to play important roles in plants against high-temperature (HT) stress. Their main function is to act as molecular chaperones for other proteins. It has also been proven that HSPs have a protective effect during other environmental stresses including low temperature (LT). To the best of our knowledge, the expression and role of HSPs in plants that have been exposed to LT have not yet been sufficiently reviewed. The aims of this minireview were (1) to briefly describe the origin, classification, structure, localisation and functions of HSPs, (2) to present the current knowledge about the changes in the accumulation of HSPs in plants that have been exposed to LT, (3) to discuss some of the molecular changes that occur during LT action and that lead to the accumulation of HSPs in plants and (4) to discuss the potential role of HSPs in acquiring tolerance to cold and frost in plants including economically important crop species. Some directions of research on the role of HSPs in plants growing in LT conditions are proposed.

Inhibiting AGS Cancer Cell Proliferation through the Combined Application of Aucklandiae Radix and Hyperthermia: Investigating the Roles of Heat Shock Proteins and Reactive Oxygen Species.

Cancer is a major global health concern. To address this, the combination of traditional medicine and newly appreciated therapeutic modalities has been gaining considerable attention. This study explores the combined effects of Aucklandiae Radix (AR) and 43 °C hyperthermia (HT) on human gastric adenocarcinoma (AGS) cell proliferation and apoptosis. We investigated the synergistic effects of AR and HT on cell viability, apoptosis, cell cycle progression, and reactive oxygen species (ROS)-dependent mechanisms. Our findings suggest that the combined treatment led to a notable decrease in AGS cell viability and increased apoptosis. Furthermore, cell cycle arrest at the G2/M phase contributed to the inhibition of cancer cell proliferation. Notably, the roles of heat shock proteins (HSPs) were highlighted, particularly in the context of ROS regulation and the induction of apoptosis. Overexpression of HSPs was observed in cells subjected to HT, whereas their levels were markedly reduced following AR treatment. The suppression of HSPs and the subsequent increase in ROS levels appeared to contribute to the activation of apoptosis, suggesting a potential role for HSPs in the combined therapy's anti-cancer mechanisms. These findings provide valuable insights into the potential of integrating AR and HT in cancer and HSPs.

Interactive abiotic and biotic stressor impacts on a stream-dwelling amphibian.

Organisms within freshwater and marine environments are subject to a diverse range of often co-occurring abiotic and biotic stressors. Despite growing awareness of the complex multistress systems at play in aquatic ecosystems, many questions remain regarding how simultaneous stressors interact with one another and jointly impact aquatic species. We looked at multistress interactions in a protected stream ecosystem in Mendocino County, California. Specifically, we examined how diurnal temperature variation, turbidity, and predator cues altered the movement speed of larval Pacific giant salamanders (Dicamptodon tenebrosus). In a second experiment, we looked at how simulated low-flow summer conditions impact the expression of heat-shock proteins (HSPs) in the same species. Larvae moved almost one and a half times faster in the presence of chemical cues from trout and suspended sediment, and almost two times faster when both sediment and trout cues were present but were only marginally affected by temperature and visual cues from conspecifics. Interestingly, the order of stressor exposure also appeared to influence larval speed, where exposure to sediment and trout in earlier trials tended to lead to faster speeds in later trials. Additionally, larvae exposed to low-flow conditions had more variable, but not statistically significantly higher, expression of HSPs. Our findings highlight the potential interactive effects of an abiotic stressor, sedimentation, and a biotic stressor, and predator chemical cues on an ecologically important trait: movement speed. Our findings also demonstrate the likely role of HSPs in larval salamander survival in challenging summer conditions. Taken together, these findings show that larval D. tenebrosus responds behaviorally to biotic and abiotic stressors and suggests a possible pathway for physiological tolerance of environmental stress. Consideration of multistress systems and their effects is important for understanding the full effects of co-occurring stressors on aquatic organisms to guide appropriate conservation and management efforts based on ecologically relevant responses of organisms within an environment.

The Role of HSP90 and TRAP1 Targets on Treatment in Hepatocellular Carcinoma.

Hepatocellular Carcinoma (HCC) is the predominant form of liver cancer and arises due to dysregulation of the cell cycle control machinery. Heat Shock Protein 90 (HSP90) and mitochondrial HSP90, also referred to as TRAP1 are important critical chaperone target receptors for early diagnosis and targeting HCC. Both HSP90 and TRAP1 expression was found to be higher in HCC patients. Hence, the importance of HSP90 and TRAP1 inhibitors mechanism and mitochondrial targeted delivery of those inhibitors function is widely studied. This review also focuses on importance of protein-protein interactions of HSP90 and TRAP1 targets and association of its interacting proteins in various pathways of HCC. To further elucidate the mechanism, systems biology approaches and computational biology approach studies are well explored in the association of inhibition of herbal plant molecules with HSP90 and its mitochondrial type in HCC.

Overexpression of HSP27 accelerates stress-induced gastric ulcer healing via the CXCL12/CXCR4 axis.

Chronic stress often triggers gastrointestinal complications, including gastric injury and ulcers. Understanding the role of heat shock protein 27 (HSP27) in stress-induced gastric ulcers could unveil novel therapeutic targets. Here, we established a stress-induced gastric ulcer rat model using water immersion restraint stress and administered adenovirus-packaged HSP27 overexpression vector. Gastric ulcer severity was scored, and mucosal changes were assessed. Gastric epithelial and endothelial cells were treated with lipopolysaccharide and transfected with HSP27 overexpression vectors to evaluate cell viability, migration and angiogenesis. Expression levels of HSP27, C-X-C motif chemokine ligand 12 (CXCL12) and C-X-C motif chemokine receptor 4 (CXCR4) were measured in tissues and cells. HSP27 expression was initially low during stress-induced gastric ulceration but increased during ulcer healing. HSP27 overexpression accelerated ulcer healing in rats, promoting gastric epithelial cell proliferation and migration and gastric endothelial cell angiogenesis through the CXCL12/CXCR4 axis. Inhibitor IT1t reversed the effects of HSP27 overexpression on cell proliferation, migration and angiogenesis. In summary, HSP27 overexpression facilitated ulcer healing, which was partially mediated by the CXCL12/CXCR4 axis.

The Multiple Roles of Heat Shock Proteins in the Development of Inflammatory Bowel Disease.

Inflammatory bowel disease (IBD), a chronic inflammatory condition of the human intestine, comprises Crohn's Disease (CD) and Ulcerative Colitis (UC). IBD causes severe gastrointestinal symptoms and increases the risk of developing colorectal carcinoma. Although the etiology of IBD remains ambiguous, complex interactions between genetic predisposition, microbiota, epithelial barrier, and immune factors have been implicated. The disruption of intestinal homeostasis is a cardinal characteristic of IBD. Patients with IBD exhibit intestinal microbiota dysbiosis, impaired epithelial tight junctions, and immune dysregulation; however, the relationship between them is not completely understood. As the largest body surface is exposed to the external environment, the gastrointestinal tract epithelium is continuously subjected to environmental and endogenous stressors that can disrupt cellular homeostasis and survival. Heat shock proteins (HSPs) are endogenous factors that play crucial roles in various physiological processes, such as maintaining intestinal homeostasis and influencing IBD progression. Specifically, HSPs share an intricate association with microbes, intestinal epithelium, and the immune system. In this review, we aim to elucidate the impact of HSPs on IBD development by examining their involvement in the interactions between the intestinal microbiota, epithelial barrier, and immune system. The recent clinical and animal models and cellular research delineating the relationship between HSPs and IBD are summarized. Additionally, new perspectives on IBD treatment approaches have been proposed.

HSP70 Is a Critical Regulator of HSP90 Inhibitor's Effectiveness in Preventing HCl-Induced Chronic Lung Injury and Pulmonary Fibrosis.

Exposure to hydrochloric acid (HCl) can provoke acute and chronic lung injury. Because of its extensive production for industrial use, frequent accidental exposures occur, making HCl one of the top five chemicals causing inhalation injuries. There are no Food and Drug Administration (FDA)-approved treatments for HCl exposure. Heat shock protein 90 (HSP90) inhibitors modulate transforming growth factor-β (TGF-β) signaling and the development of chemical-induced pulmonary fibrosis. However, little is known on the role of Heat Shock Protein 70 (HSP70) during injury and treatment with HSP90 inhibitors. We hypothesized that administration of geranylgeranyl-acetone (GGA), an HSP70 inducer, or gefitinib (GFT), an HSP70 suppressant, alone or in combination with the HSP90 inhibitor, TAS-116, would improve or worsen, respectively, HCl-induced chronic lung injury in vivo and endothelial barrier dysfunction in vitro. GGA, alone, improved HCl-induced human lung microvascular endothelial cells (HLMVEC) barrier dysfunction and, in combination with TAS-116, improved the protective effect of TAS-116. In mice, GGA reduced HCl toxicity and while TAS-116 alone blocked HCl-induced chronic lung injury, co-administration with GGA, resulted in further improvement. Conversely, GFT potentiated HCl-induced barrier dysfunction and impaired the antidotal effects of TAS-116. We conclude that combined treatments with HSP90 inhibitors and HSP70 inducers may represent a novel therapeutic approach to manage HCl-induced chronic lung injury and pulmonary fibrosis.

Heat shock proteins, thermotolerance, and insecticide resistance in mosquitoes.

Mosquitoes transmit pathogens that pose a threat to millions of people globally. Unfortunately, widespread insecticide resistance makes it difficult to control these public health pests. General mechanisms of resistance, such as target site mutations or increased metabolic activity, are well established. However, many questions regarding the dynamics of these adaptations in the context of developmental and environmental conditions require additional exploration. One aspect of resistance that deserves further study is the role of heat shock proteins (HSPs) in insecticide tolerance. Studies show that mosquitoes experiencing heat stress before insecticide exposure demonstrate decreased mortality. This is similar to the observed reciprocal reduction in mortality in mosquitoes exposed to insecticide prior to heat stress. The environmental shifts associated with climate change will result in mosquitoes occupying environments with higher ambient temperatures, which could enhance existing insecticide resistance phenotypes. This physiological relationship adds a new dimension to the problem of insecticide resistance and further complicates the challenges that vector control and public health personnel face. This article reviews studies illustrating the relationship between insecticide resistance and HSPs or hsp genes as well as the intersection of thermotolerance and insecticide resistance. Further study of HSPs and insecticide resistance could lead to a deeper understanding of how environmental factors modulate the physiology of these important disease vectors to prepare for changing climatic conditions and the development of novel strategies to prevent vector-borne disease transmission.

Role of heat shock protein 90 in hypoxia-induced angiogenesis and epithelial-mesenchymal transition for esophageal squamous cancer cells.

395 Background: Hypoxia is known as an important trigger for the development and progression of human cancers. Heat shock proteins (Hsps) may be up-regulated in response to cellular stressors including hypoxia. To date, the functional role of Hsps within hypoxic tumor microenvironment for esophageal squamous cell cancer (ESCC) remains poorly defined. Methods: CoCl2 was used to induce hypoxia that mimics a hypoxic tumor microenvironment in cultured ESCC cells. Successful induction of hypoxia was confirmed by 2’,7’ –dichlorofluorescein diacetate (DCFDA) assay by detection of cellular reactive oxygen species (ROS). 7-Dimethylaminoethylamino-17-demethoxygeldanamycin (17-DMAG), a selective Hsp90 inhibitor, was used to treat 2 ESCC cell lines, KYSE-170 and -510 cells pretreated with or without CoCl2, an agent to induce a hypoxic tumor microenvironment. Cytotoxicity (MTT) and migration assays were conducted in KYSE-17 and -510 ESCC cells in response to different concentrations of CoCl2, followed by protein expression of Hsp 90, vascular endothelial growth factor (VEGF), hypoxia-inducible factor-1a (HIF-1a), mTOR as well as markers related epithelial-mesenchymal transition (EMT) such as snail or E-cadherin, by immunoblot or ELISA. In parallel, cell proliferation and migration assays of ESCC cells were analyzed. Results: CoCl2 induced hypoxia was supported by an induction of reactive oxygen species (ROS). CoCl2 (200 mM) significantly suppressed cell viability and proliferation with a concomitant up-regulation of VEGF and HIF-1a in a dose-dependent fashion. In contrast, cell migration was significantly increased in response to CoCl2, while down-regulating E-cadherin with concomitant increase in Snail expression. 17-DMAG decreased expression of VEGF and HIF-1a. In addition, it inhibited cell migration and invasion of ESCC cells were analyzed. Conclusions: Our data have shown that CoCl2 induced hypoxia promotes EMT and angiogenesis, which are inhibited by 17-DMAG, suggesting that hypoxia induced EMT and angiogenesis is Hsp 90 dependent in ESCC.

Pre-heating stress associated with acute oral leucine supplementation effects in rat gastrocnemius muscle: Implications for protein synthesis signaling pathways

Skeletal muscle is a highly plastic tissue. The role of heat shock protein 72 (Hsp72) in heat stress-induced skeletal muscle hypertrophy has been well demonstrated; however, the precise mechanisms remain unclear. Essential amino acids, such as leucine, mainly mediate muscle protein synthesis. We investigated the effects of pre-heating and increased Hsp72 expression on the mechanistic target of rapamycin (mTOR) signaling and protein synthesis following leucine administration in rat gastrocnemius muscle. To ensure increased Hsp72 expression in both the red and white portions of the muscle, one leg of male Wistar rats (10-week-old, n = 23) was heat-stressed in 43 °C water for 30 min twice at a 48-h-interval (heat-stressed leg, HS leg). The contralateral leg served as a non-heated internal control (CT leg). After the recovery period (48 h), rats were divided into the pre-administration or oral leucine administration groups. We harvested the gastrocnemius muscle (red and white parts) prior to administration and 30 and 90 min after leucine treatment (n = 7–8 per group) and intramuscular signaling responses to leucine ingestion were determined using western blotting. Heat stress significantly upregulated the expression of Hsp72 and was not altered by leucine administration. Although the phosphorylation levels of mTOR/S6K1 and ERK were similar regardless of heating, 4E-BP1 was less phosphorylated in the HS legs than the CT legs after leucine administration in the red portion of the muscles (P < 0.05). Moreover, c-Myc expression differed significantly after leucine administration in both the red and white portions of the muscles. Our findings indicate that following oral leucine administration, pre-heating partially blunted the muscle protein synthesis signaling response in the rat gastrocnemius muscle.