Role Of Hsp90 Research Articles

Hsp90 Promotes Gastric Cancer Cell Metastasis and Stemness by Regulating the Regional Distribution of Glycolysis-Related Metabolic Enzymes in the Cytoplasm.

Heat-shock protein 90 (Hsp90) plays a crucial role in tumorigenesis and tumor progression; however, its mechanism of action in gastric cancer (GC) remains unclear. Here, the role of Hsp90 in GC metabolism is the focus of this research. High expression of Hsp90 in GC tissues can interact with glycolysis, collectively affecting prognosis in clinical samples. Both in vitro and in vivo experiments demonstrate that Hsp90 is able to regulate the migration and stemness properties of GC cells. Metabolic phenotype analyses indicate that Hsp90 influences glycolytic metabolism. Mechanistically, Hsp90 interacts with glycolysis-related enzymes, forming multienzyme complexes to enhance glycolysis efficiency and yield. Additionally, Hsp90 binds to cytoskeleton-related proteins, regulating the regional distribution of glycolytic enzymes at the cell margin and lamellar pseudopods. This effect could lead to a local increase in efficient energy supply from glycolysis, further promoting epithelial-mesenchymal transition (EMT) and metastasis. In summary, Hsp90, through its interaction with metabolic enzymes related to glycolysis, forms multi-enzyme complexes and regulates regional distribution of glycolysis by dynamic cytoskeletal adjustments, thereby promoting the migration and stemness of GC cells. These conclusions also support the potential for a combined targeted approach involving Hsp90, glycolysis, and the cytoskeleton in clinical therapy.

Role of HSP90 in Type 2 Diabetes Mellitus and Its Association with Liver Diseases.

Non-alcoholic fatty acid liver disease (NAFLD), non-alcoholic steatohepatitis (NASH) and hepatocellular carcinoma (HCC) are the fatal liver diseases which encompass a spectrum of disease severity associated with increased risk of type 2 diabetes mellitus (T2DM), a metabolic disorder. Heat shock proteins serve as markers in early prognosis and diagnosis of early stages of liver diseases associated with metabolic disorder. This review aims to comprehensively investigate the significance of HSP90 isoforms in T2DM and liver diseases. Additionally, we explore the collective knowledge on plant-based drug compounds that regulate HSP90 isoform targets, highlighting their potential in treating T2DM-associated liver diseases. Furthermore, this review focuses on the computational systems' biology and next-generation sequencing technology approaches that are used to unravel the potential medicine for the treatment of pleiotropy of these 2 diseases and to further elucidate the mechanism.

Ketoconazole induces reversible antifungal drug tolerance mediated by trisomy of chromosome R in Candida albicans.

The emergence of tolerance to antifungal agents in Candida albicans complicates the treatment of fungal infections. Understanding the mechanisms underlying this tolerance is crucial for developing effective therapeutic strategies. This study aims to elucidate the genetic and molecular basis of ketoconazole tolerance in C. albicans, focusing on the roles of chromosomal aneuploidy, Hsp90, and calcineurin. The wild-type C. albicans strain SC5314 was exposed to increasing concentrations of ketoconazole (0.015-32 μg/mL) to select for tolerant adaptors. Disk diffusion and spot assays were used to assess tolerance. Whole-genome sequencing identified chromosomal changes in the adaptors. The roles of Hsp90 and calcineurin in maintaining and developing ketoconazole tolerance were investigated using specific inhibitors and knockout strains. Adaptors exhibited tolerance to ketoconazole concentrations up to 16 μg/mL, a significant increase from the parent strain's inhibition at 0.015 μg/mL. All tolerant adaptors showed amplification of chromosome R, with 29 adaptors having trisomy and one having tetrasomy. This aneuploidy was unstable, reverting to euploidy and losing tolerance in drug-free conditions. Both Hsp90 and calcineurin were essential for maintaining and developing ketoconazole tolerance. Inhibition of these proteins resulted in loss of tolerance. The efflux gene CDR1 was not required for the development of tolerance. Chromosome R trisomy and tetrasomy induce cross-tolerance to other azole antifungal agents, including clotrimazole and miconazole, but not to other antifungal classes, such as echinocandins and pyrimidines, exemplified by caspofungin and 5-flucytosine. Ketoconazole tolerance in C. albicans is mediated by chromosomal aneuploidy, specifically chromosome R amplification, and requires Hsp90 and calcineurin. These findings highlight potential targets for therapeutic intervention to combat antifungal tolerance and improve treatment outcomes.

Hsp70 Knockdown in the Brine Shrimp Artemia franciscana: Implication on Reproduction, Immune Response and Embryonic Cuticular Structure.

The potential functional role(s) of heat shock protein 70 (Hsp70) in the brine shrimp, Artemia franciscana, a crucial crustacean species for aquaculture and stress response studies, was investigated in this study. Though we have previously reported that Hsp70 knockdown may have little or no impact on Artemia development, the gestational survival and number of offspring released by adult females were impaired by obscuring Hsp70 synthesis. Transcriptomic analysis revealed that several cuticle and chitin synthetic genes were downregulated, and carbohydrate metabolic genes were differentially expressed in Hsp70-knockdown individuals. A more comprehensive microscopic examination performed in this study revealed exoskeleton structural destruction and abnormal eye lenses featured in Hsp70-deficient adult females 48h after Hsp70 dsRNA injection. Cysts produced by these Hsp70-deficient broods, instead, had a defective shell and were smaller in size, whereas nauplii had shorter first antennae and a rougher body epicuticle surface. Changes in carbohydrate metabolism caused by Hsp70 knockdown affected glycogen levels in adult Artemia females, as well as trehalose in cysts released from these broods, indicating that Hsp70 may play a role in energy storage preservation. Outcomes from this work provided novel insights into the roles of Hsp70 in Artemia reproduction performance, cyst formation, and exoskeleton structure preservation. The findings also support our previous observation that Hsp70 knockdown reduced Artemia nauplius tolerance to bacterial pathogens, which could be explained by the fact that loss of Hsp70 downregulated several Toll receptor genes (NT1 and Spaetzle) and reduced the integrity of the exoskeleton, allowing pathogens to enter and cause infection, ultimately resulting in mortality.

The role of HSP70 in the regulation of the tolerogenic potential of dendritic cells derived from cryopreserved progenitors of bone marrow origin

The role of HSP70 in the regulation of the tolerogenic potential of dendritic cells derived from cryopreserved progenitors of bone marrow origin

Small but powerful: The role of HSP in bacterial infectious disease pathogenesis- A mini-review of recent findings

Heat Shock Proteins (Hsp) are evolutionarily conserved ubiquitous molecular chaperones usually produced when cells are exposed to temperatures beyond their normal growth temperature. They are a group of ATP-independent chaperons pivotal for cell survival and proliferation. This group of proteins has been well studied over the years. However, recent investigations leveraging the available Whole Genome Sequencing (WGS) approach are beginning to shed more light on how this protein interacts with other intracellular proteins to modulate bacterial virulence and pathogenesis. Bacteria cells that manufacture HSPs can survive at higher temperatures. Certain heat-shock proteins have a refolding or degradation action that can save the bacterial cell even in extreme stress demands and even help some bacteria transition from being commensal to a pathogen. Certain HSPs are virulence factors, while others modulate bacterial pathogenesis increasing bacterial resistance to host immunological attack. Interestingly, others also influence certain virulence gene expressions. Several mechanisms govern heat shock response. Moreover, the employment of specific regulatory proteins that exert a positive or negative effect on the initiation of transcription by the RNA polymerase enzyme is successful and efficient in controlling heat-shock gene transcription. Interestingly, most pathogens use several approaches to reprogram gene transcription in response to diverse stress rapidly. In this mini-review, we tactfully discussed the recent update on HSP in bacteria virulence and how these proteins could serve as potential drug targets. Moreover, we provided an overview of how HSPs are regulated in bacterial pathogens favouring bacterial survival in diverse cellular niches.

Proteostasis of heat shock protein 90 in skeletal muscles of the long-tailed ground squirrel during hibernation

We investigated changes in the content of heat shock protein 90 in m. soleus (comprised of mainly fibers expressing the MyHC slow isoform I) and m. gastrocnemius (composed of mainly fibers expressing the MyHC fast isoforms II) of the long-tailed ground squirrel Urocitellus undulatus in different periods of the annual cycle: summer activity (seasonal control), hypothermia/torpor, winter (interbout) activity. The content of the protein in both muscles was found not to change throughout the entire hibernation period despite the development of atrophic changes, more pronounced in fast m. gastrocnemius. The role of HSP90 in maintaining the stability of giant sarcomeric titin protein molecules is discussed with reference to animal's entry into and exit from hypothermia, when the activity of calpain proteases increases due to the increased content of Ca2+ in the cytosol of muscle cells; and with respect to the torpor, when the activity of calpains is, most likely, not inhibited completely. During the interbout activity with an observed increased titin turnover in squirrel's striated muscles, a constant content of HSP90 appears to be required for the correct folding of newly synthesized titin molecules and their integration into sarcomeres, as well as for the removal of misfolded titin molecules and other proteins. Thus, HSP90 proteostasis in skeletal muscles of the long-tailed ground squirrel can contribute to maintaining a steady-state level of titin and, possibly, other sarcomeric proteins during hibernation, which, in turn, will contribute to maintaining a highly ordered sarcomeric structure and the necessary level of muscle contractile activity in different phases of the torpor-arousal cycle.

Closest horizons of Hsp70 engagement to manage neurodegeneration.

Our review seeks to elucidate the current state-of-the-art in studies of 70-kilodalton-weighed heat shock proteins (Hsp70) in neurodegenerative diseases (NDs). The family has already been shown to play a crucial role in pathological aggregation for a wide spectrum of brain pathologies. However, a slender boundary between a big body of fundamental data and its implementation has only recently been crossed. Currently, we are witnessing an anticipated advancement in the domain with dozens of studies published every month. In this review, we briefly summarize scattered results regarding the role of Hsp70 in the most common NDs including Alzheimer's disease (AD), Parkinson's disease (PD), and amyotrophic lateral sclerosis (ALS). We also bridge translational studies and clinical trials to portray the output for medical practice. Available options to regulate Hsp70 activity in NDs are outlined, too.

Tanespimycin and rapamycin exhibit antifungal activity against Colletotrichum gloeosporioides and enhance mango resistance to anthracnose via differentially modulating heat shock response

Postharvest mango (Mangifera indica L.) fruit suffer tremendous loss due to anthracnose inflicted by Colletotrichum spp. Fungicides and heat treatment are often used to control the disease, while biocontrol agents are eco-friendly alternatives. Streptomyces are antagonistic organisms against plant pathogens; however, the mechanisms and active components are unclear. Here, we evaluated the antifungal actions of S. hygroscopicus metabolites tanespimycin and rapamycin against anthracnose. Within the range of 0.01–0.1 μM, tanespimycin and rapamycin reduced fungal growth by at least 60.4% and 40.4%, respectively in vitro. In mango fruit, tanespimycin upregulated MiHSP101, MiHSP90, MiHSP70, and MiHSP18.2 by 5.8-, 1.9-, 4.8-, and 3.3-fold, respectively, and increased HSP101 and HSP70 protein by 2.2-fold. On the other hand, rapamycin did not affect HSP expression. Pathogen-challenge assays revealed tanespimycin and rapamycin exerted antifungal and defense-eliciting dual actions, where pre-challenge treatment of tanespimycin and rapamycin inhibited pathogen growth by 73.7% and 78.4%, respectively in mango 5 d post infection. Finally, in a 20 °C storage experiment, tanespimycin and rapamycin extended the fruit shelf life by 6 d and exerted comparable antifungal effects as hot water treatment without deteriorating fruit quality. In conclusion, we elucidated the antifungal and defense-eliciting actions of S. hygroscopicus metabolites and revealed mechanistic discrepancies regarding HSP regulation. These findings support the development of new disease management strategies and advance the knowledge regarding the roles of HSP in crop defense.

Role of heat shock proteins in oncogenesis and strategy for treating cancers using Drosophila model

A cluster of closely stored molecules that are engaged in different cellular processes is the mammalian HSP90 protein family. HSP90 works with HSP70 but is not dependent on the cochaperone of HSP90. HSPs are molecular chaperones required to fold, stabilize, and degrade proteins that are responsible for multiple tumor types. Hence targeting HSP90 and HSP70 presents a striking strategy for treating cancers. The present review article provides an overview of the structure, mode of action as well as role of HSP90 and HSP70. They are part of key regulatory processes that directly influence oncogenic pathways. As Drosophila melanogaster acts as an appropriate model system for research studies involving the above-stated disorders, emphasis has been put on summarizing some of the research studies in oncogenesis.

Cellular network of damage caused by exposure to high ambient temperature in Wistar rats: The role of Hsp70

ObjectivesAs a universal cytoprotective protein, Hsp70 is used to monitor the effects of environmental temperature changes, increasing the survival rate of cells exposed to stress, as well as the role of protein in cardiovascular disease, body decay and cell aging. Our research aims to to examine whether changes in serum protein 70 (Hsp70) values due to exposure to water temperature (41 °C and 44 °C) may indicate a mechanism of cardiomyocyte damage due to hyperthermia. MethodsA total of 40 adult albino Wistar rats, of known gender and body weight from 250 g to 300 g were used as material in this research. Rats were housed in polypropylene cages with optimum environmental conditions. Depending on the temperature of the water (WT) to which they were exposed, rats were randomized into the following groups.WT 37 °C (n = 8); WT 41 °C, antemortem (n = 8), WT 41 °C, postmortem (n = 8); WT 44 °C, antemortem (n = 8), WT 44 °C, postmortem (n = 8). Blood samples for determination of Hsp70 were taken before and after the expiration of the given duration of the experiment of 20 min or death. The Hsp70 level was determined by Enzyme-Linked Immunosorbent Assay (ELISA) ResultsHsp70 basal values in serum were significantly different, p = 0.004 pg/ml, and in the groups depending on the duration of exposure to Hsp70, p = 0.002. Serum Hsp70 values after being exposed to water temperature were significantly different according to the group, p = 0.009. Significant lower Hsp70 levels were found in the control group according to G41 p = 0.006 and G44, p = 0.002. Insignificant differences in Hsp70 level were found among theseG41 and G44, p > 0.005. The concentration of Hsp70 in rat serum and ≥ 31.36 ng/ml indicates exposure to temperatures higher than 37 °C (sensitivity 85.71%, specificity 83.33%, PPV 96%, and NPV 55%, p = 0.002). ConclusionsAltered concentration of serum Hsp70 may show exposition to the elevated water temperature.

Role of Hsp70 in Post-Translational Protein Targeting: Tail-Anchored Membrane Proteins and Beyond.

The Hsp70 family of molecular chaperones acts as a central 'hub' in the cell that interacts with numerous newly synthesized proteins to assist in their biogenesis. Apart from its central and well-established role in facilitating protein folding, Hsp70s also act as key decision points in the cellular chaperone network that direct client proteins to distinct biogenesis and quality control pathways. In this paper, we review accumulating data that illustrate a new branch in the Hsp70 network: the post-translational targeting of nascent membrane and organellar proteins to diverse cellular organelles. Work in multiple pathways suggests that Hsp70, via its ability to interact with components of protein targeting and translocation machineries, can initiate elaborate substrate relays in a sophisticated cascade of chaperones, cochaperones, and receptor proteins, and thus provide a mechanism to safeguard and deliver nascent membrane proteins to the correct cellular membrane. We discuss the mechanistic principles gleaned from better-studied Hsp70-dependent targeting pathways and outline the observations and outstanding questions in less well-studied systems.

Abstract 1281: Role of Hsp90 in regulating sensitivity of Cryptococcus neoformans to fluconazole

Abstract 1281: Role of Hsp90 in regulating sensitivity of Cryptococcus neoformans to fluconazole

Abstract 2311: Shaking up Spheroids: The role of Hsp27 and aB-crystallin in anoikis inhibition during ovarian cancer spheroid formation

Abstract 2311: Shaking up Spheroids: The role of Hsp27 and aB-crystallin in anoikis inhibition during ovarian cancer spheroid formation

HSP90 drives the Rab11a-mediated vesicular transport of the cell surface receptors in osteoclasts.

Rab11a, which ubiquitously localizes to early and recycling endosomes, is required for regulating the vesicular transport of cellular cargos. Interestingly, our previous study revealed that Rab11a served as a negative regulator of osteoclastogenesis by facilitating the lysosomal proteolysis of (1) colony-stimulating factor-1 (c-fms) receptor and (2) receptor activator of nuclear factor-κB (RANK) receptor, thereby resulting in inhibition of osteoclast (OC) differentiation, maturation, and bone-resorbing activity. However, the molecular mechanisms of how Rab11a negatively affected osteoclastogenesis were largely unknown. Heat shock protein (HSP90), including two isoforms HSP90αand HSP90β, necessitates the stability, maturation, and activity of a broad range of its clients, and is essentially required for a vast array of signal transduction pathways in nonstressful conditions. Furthermore, cumulative evidence suggests that HSP90 is a vital element of the vesicular transport network. Indeed, our recent study revealed thatHSP90, a novel effector protein of Rab11b, modulatedRab11b-mediated osteoclastogenesis. In this study, we also found that Rab11a interacted with both HSP90α and HSP90β in OCs. Upon blockade of HSP90 ATPase activity by a specific inhibitor(17-allylamino-demethoxygeldanamycin), we showed that (1) the ATPase domain of HSP90 was a prerequisite for the interaction between HSP90 and Rab11a, and (2) the interaction of HSP90 to Rab11a sufficiently maintained the inhibitory effects of Rab11a on osteoclastogenesis. Altogether, our findings undoubtedly indicate a novel role of HSP90 in regulating Rab11a-mediated osteoclastogenesis.

Hsp90 Regulates GCRV-II Proliferation by Interacting with VP35 as Its Receptor and Chaperone.

The frequent outbreak of grass carp hemorrhagic disease caused by grass carp reovirus (GCRV), especially the mainly prevalent type II GCRV (GCRV-II), has seriously affected the grass carp culture in China. However, its pathogenic mechanism is still far from clear. In this study, the GCRV-II outer capsid protein VP35 was used as bait to capture interacting partners from Ctenopharyngon idellus kidney (CIK) cells, and heat shock protein 90 (Hsp90) was selected and confirmed interacting with VP35 through the C-terminal domain of Hsp90. Knockdown of Hsp90 or inhibition of Hsp90 activity suppressed GCRV-II proliferation, demonstrating that Hsp90 is an essential factor for GCRV-II proliferation. The confocal microscopy and flow cytometry showed that Hsp90 localized at both membrane and cytoplasm of CIK cells. The entry of GCRV-II into CIK cells was efficiently blocked by incubating the cells with Hsp90 antibody or by pretreating the virus with recombinant Hsp90 protein. Whereas overexpression of Hsp90 in CIK cells, grass carp ovary (GCO) cells, or 293T cells promoted GCRV-II entry, indicating that the membrane Hsp90 functions as a receptor of GCRV-II. Furthermore, Hsp90 interacted with clathrin and mediated GCRV-II entry into CIK cells through clathrin endocytosis pathway. In addition, we found that the cytoplasmic Hsp90 acted as a chaperone of VP35 because inhibition of Hsp90 activity enhanced VP35 polyubiquitination and degraded VP35 through the proteasome pathway. Collectively, our data suggest that Hsp90 functions both as a receptor for GCRV-II entry and a chaperone for the maturation of GCRV-II VP35, thus ensuring efficient proliferation of GCRV-II. IMPORTANCE Identification of viral receptors has always been the research hot spot in virus research field as receptor functions at the first stage of viral infection, which can be designed as efficient antiviral drug targets. GCRV-II, the causative agent of the grass carp epidemic hemorrhagic disease, has caused tremendous losses in grass carp culture in China. To date, the receptor of GCRV-II remains unknown. This study focused on identifying cellular receptor interacting with the GCRV-II outer capsid protein VP35, studying the effects of their interaction on GCRV-II proliferation, and revealing the underlying mechanisms. We demonstrated that Hsp90 acts both as a receptor of GCRV-II by interacting with VP35 and as a chaperone for the maturation of VP35, thus ensuring efficient proliferation of GCRV-II. Our data provide important insights into the role of Hsp90 in GCRV-II life cycle, which will help understand the mechanism of reovirus infection.

Inhibition of HSP90 Preserves Blood-Brain Barrier Integrity after Cortical Spreading Depression.

Cortical spreading depression (CSD) is a pathophysiological mechanism underlying headache disorders, including migraine. Blood–brain barrier (BBB) permeability is increased during CSD. Recent papers have suggested that heat shock proteins (HSP) contribute to the integrity of the blood–brain barrier. In this study, the possible role of HSP90 in CSD-associated blood–brain barrier leak at the endothelial cell was investigated using an in vitro model, for the blood–endothelial barrier (BEB), and an in vivo model with an intact BBB. We measured barrier integrity using trans endothelial electric resistance (TEER) across a monolayer of rodent brain endothelial cells (bEnd.3), a sucrose uptake assay, and in situ brain perfusion using female Sprague Dawley rats. CSD was induced by application of 60 mM KCl for 5 min in in vitro experiments or cortical injection of KCl (1 M, 0.5 µL) through a dural cannula in vivo. HSP90 was selectively blocked by 17-AAG. Our data showed that preincubation with 17-AAG (1 µM) prevented the reduction of TEER values caused by the KCl pulse on the monolayer of bEnd.3 cells. The elevated uptake of 14C-sucrose across the same endothelial monolayer induced by the KCl pulse was significantly reduced after preincubation with HSP90 inhibitor. Pre-exposure to 17-AAG significantly mitigated the transient BBB leak after CSD induced by cortical KCl injection as determined by in situ brain perfusion in female rats. Our results demonstrated that inhibition of HSP90 with the selective agent 17-AAG reduced CSD-associated BEB/BBB paracellular leak. Overall, this novel observation supports HSP90 inhibition mitigates KCl-induced BBB permeability and suggests the development of new therapeutic approaches targeting HSP90 in headache disorders.

Abstract 3232: Combined inhibition of mTOR and HSP90 potentiates cisplatin antitumor effect and reverts cisplatin resistance in vitro and in vivo models of epithelial ovarian cancer by modulating HSF1-dependent transactivation

Abstract INTRODUCTION: Epithelial ovarian cancer (EOC) represents the most lethal gynecological disease, with a 5-year relative survival rate of 46% after the diagnosis. The standard treatment of advanced EOC is based on surgery, followed by platinum (Pt)-based chemotherapy. However, the development of platinum resistant disease could occur and strongly impact on the survival of EOC patients for whom we still do not have valid therapeutic options. By using a proteomic approach followed by a bioinformatic analysis, we previously validated the role of HSP90 in the mechanism of platinum-resistance. Here, we propose a novel therapeutic strategy based on the combined pharmacologic inhibition of HSP90 and mTOR to further potentiate Pt-based chemotherapy and to revert Pt-resistance in EOC and non-small-cell lung cancer (NSCLC) models. METHODS: TOV-112D parental and Pt-resistant cells were characterized by phosphoproteomics followed by functional analysis and proteins validation by western blot. Synergistic anti-tumor effect was evaluated in Pt-sensitive and Pt-resistant EOC and NSCLC cell lines by calculating combination indexes (CI), colony formation assay, apoptosis and DNA damage, as well as on 3D in vitro microtissues obtained by co-culturing cancer cells with normal fibroblasts and in vivo EOC and NSCLC xenograft models. RESULTS: 542 differentially phosphorylated expressed proteins were identified in Pt-resistant TOV-112D compared with parental cells, and mTOR and the transcription factor HSF1 emerged as the most enriched pathways. The up-regulation of the phosphorylated form of PDK1, AKT, mTOR and rpS6 was observed in Pt-resistant compared to parental cells. Moreover, we also demonstrated the up-regulation of the activity of HSF1 along with the elevation of its targets such as heat shock proteins HSP90, HSP70 and HSP40, crucial components of chaperone complex machinery. Interestingly, among the differentially expressed proteins, we identified the kinase DYRK2 able to phosphorylate HSF1, supporting its transactivation. Accordingly, the combination of HSP90 inhibitor ganetespib and the mTOR inhibitor temsirolimus plus cisplatin, synergistically reduced colony formation, cancer cells and microtissues cell growth in vitro by increasing DNA-damage and apoptosis and in vivo by enhancing mouse survival. Mechanistically, the triple combination treatment, impaired the proteins involved in mTOR signalling and HSF1 transactivation. Notably, all these data were confirmed in Pt-resistant NSCLC models, supporting the possibility that the same mechanism is present in different tumor types. CONCLUSIONS: Our findings identify a promising new antitumor strategy based on the combination of HSP90 and mTOR inhibitors to revert Pt-resistance that that warrant further clinical evaluation. Citation Format: Rita Lombardi, Laura Addi, Biagio Pucci, Maura Sonego, Maria Serena Roca, Francesca Capone, Federica Iannelli, Francesca Bruzzese, Gustavo Baldassarre, Alfredo Budillon. Combined inhibition of mTOR and HSP90 potentiates cisplatin antitumor effect and reverts cisplatin resistance in vitro and in vivo models of epithelial ovarian cancer by modulating HSF1-dependent transactivation [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 3232.

Djhsp60 Is Required for Planarian Regeneration and Homeostasis.

HSP60, a well-known mitochondrial chaperone, is essential for mitochondrial homeostasis. HSP60 deficiency causes dysfunction of the mitochondria and is lethal to animal survival. Here, we used freshwater planarian as a model system to investigate and uncover the roles of HSP60 in tissue regeneration and homeostasis. HSP60 protein is present in all types of cells in planarians, but it is relatively rich in stem cells and head neural cells. Knockdown of HSP60 by RNAi causes head regression and the loss of regenerating abilities, which is related to decrease in mitotic cells and inhibition of stem cell-related genes. RNAi-HSP60 disrupts the structure of the mitochondria and inhibits the mitochondrial-related genes, which mainly occur in intestinal tissues. RNAi-HSP60 also damages the integrity of intestinal tissues and downregulates intestine-expressed genes. More interestingly, RNAi-HSP60 upregulates the expression of the cathepsin L-like gene, which may be the reason for head regression and necrotic-like cell death. Taking these points together, we propose a model illustrating the relationship between neoblasts and intestinal cells, and also highlight the essential role of the intestinal system in planarian regeneration and tissue homeostasis.

The Role of TNF-α and Its Target HSP-70 in Triggering Apoptosis in Normozoospermic and Non-Normozoospermic Samples.

Objective: Semen analysis is performed as one of the screening tests for infertility, including motility, morphology, and concentration observation. We aimed to investigate the expression rates of tumor necrosis factor-α (TNF-α) and heat shock protein (HSP)-70 as two opposite affectors of apoptosis in men with normal semen parameters and abnormal parameters to find the possible effect of this pathway on sperm parameters. We also aimed to investigate the apoptotic markers (DNA fragmentation and Caspase-3 expression) to observe the correlation of this pathway with apoptosis. Materials and Methods: A total of 32 men who applied for infertility evaluation were included in the study. Semen analysis was performed according to WHO criteria. Liquefaction time, appearance, volume, pH, viscosity, sperm concentration, total motility rate, sperm motility, and percentage of spermatozoa with normal morphology were determined. TNF-α, HSP-70, and Caspase-3 immunolocalization were scored histologically. A sperm chromatin dispersion test was used to observe DNA fragmentation. Results: There was no significant difference in TNF-α protein expression rate (mild level). The HSP-70 expression rate was lower, especially in the head region of normo. Caspase-3 was higher totally in non-normo. DNA fragmentation levels were similar in both the groups. Conclusion: From TNF-α protein expression at the mild level in both the groups, it may be hypothesized that the apoptotic pathway might not be triggered by the extrinsic pathway. We found a negative correlation between HSP-70 and Caspase-3 expressions, providing further evidence that HSP-70 works as an inhibitor to apoptosis. This, particularly on specific points, made us think the communication might begin in the anterior chamber, then flow through the cell body to the tail. HSP-70 expression was lower in normo than in non-normo, indicating the possible role of HSP-70 as an answer to any type of stressor in non-normozoospermic patients. Correspondingly, it may be concluded that HSP has an antiapoptotic effect, causing inhibition in the elimination of abnormal sperm cells impairing sperm parameters.