Membrane-Associated Heat Shock Proteins in Oncology: From Basic Research to New Theranostic Targets

Protocol of the HISTOTHERM study: assessing the response to hyperthermia and hypofractionated radiotherapy in recurrent breast cancer

Introduction

Breast cancer is globally the leading cancer in women, and despite the high 5-year survival rate the most frequent cause of cancer related deaths. Surgery, systemic therapy and radiotherapy are the three pillars of curative breast cancer treatment. However, locoregional recurrences frequently occur after initial treatment and are often challenging to treat, amongst others due to high doses of previous radiotherapy treatments. Radiotherapy can be combined with local hyperthermia to sensitize tumor cells to radiation and thereby significantly reduce the required radiation dose. Therefore, the combination treatment of mild local hyperthermia, i.e. locally heating of the tissue to 39-43°C, and re-irradiation with a reduced total dose is a relevant treatment option for previously irradiated patients. The mechanisms of this effect in the course of the therapy are to date not well understood and will be investigated in the HISTOTHERM study.

Methods and analyses

Patients with local or (loco)regional recurrent breast cancer with macroscopic tumors are included in the study. Local tumor control is evaluated clinically and histologically during the course of a combination treatment of 60 minutes mild superficial hyperthermia (39 - 43°C) using water-filtered infrared A (wIRA) irradiation, immediately followed by hypofractionated re-irradiation with a total dose of 20-24 Gy, administered in weekly doses of 4 Gy. Tumor and tumor stroma biopsies as well as blood samples will be collected prior to treatment, during therapy (at a dose of 12 Gy) and in the follow-up to monitor therapy response. The treatment represents the standard operating procedure for hyperthermia plus re-irradiation. Various tissue and blood-based markers are analyzed. We aim at pinpointing key mechanisms and markers for therapy response which may help guiding treatment decisions in future. In addition, quality of life in the course of treatment will be assessed and survival data will be evaluated.

Registration

The study is registered at the German Clinical Trials Register, Deutsches Register Klinischer Studien (DRKS00029221).

Pyridinium-Based Strategy for a Bioorthogonal Conjugation-Assisted Purification Method for Profiling Cell Surface Proteome

Cell surface proteins (CSPs) are valuable targets for therapeutic agents, but achieving highly selective CSP enrichment in cellular physiology remains a technical challenge. To address this challenge, we propose a newly developed sulfo-pyridinium ester (SPE) cross-linking probe, followed by two-step imaging and enrichment. The SPE probe showed higher efficiency in labeling proteins than similar NHS esters at the level of cell lysates and demonstrated specificity for Lys in competitive experiments. More importantly, this probe could selectively label the cell membranes in cell imaging with only negligible labeling of the intracellular compartment. Moreover, we successfully performed this strategy on MCF-7 live cells to label 425 unique CSPs from 1162 labeled proteins. Finally, we employed our probe to label the CSPs of insulin-cultured MCF-7, revealing several cell surface targets of key functional biomarkers and insulin-associated pathogenesis. The above results demonstrate that the SPE method provides a promising tool for the selective labeling of cell surface proteins and monitoring transient cell surface events.

X-ray reflectivity study of the heat shock protein Hsp70 interaction with an artificial cell membrane model

Membrane-bound heat shock protein 70 (Hsp70) apart from its intracellular localization was shown to be specifically expressed on the plasma membrane surface of tumor but not normal cells. Although the association of Hsp70 with lipid membranes is well documented the exact mechanisms for chaperone membrane anchoring have not been fully elucidated. Herein, we addressed the question of how Hsp70 interacts with negatively charged phospholipids in artificial lipid compositions employing the X-ray reflectivity (XRR) studies. In a first step, the interactions between dioleoylphosphatidylcholine (DOPC) in the presence or absence of dioleoylphosphatidylserine (DOPS) and Hsp70 had been assessed using Quartz crystal microbalance measurements, suggesting that Hsp70 adsorbs to the surface of DOPC/DOPS bilayer. Atomic force microscopy (AFM) imaging demonstrated that the presence of DOPS is required for stabilization of the lipid bilayer. The interaction of Hsp70 with DOPC/DOPS lipid compositions was further quantitatively determined by high energy X-ray reflectivity. A systematic characterization of the chaperone-lipid membrane interactions by various techniques revealed that artificial membranes can be stabilized by the electrostatic interaction of anionic DOPS lipids with Hsp70.

A new look at Hsp70 activity in phosphatidylserine-enriched membranes: chaperone-induced quasi-interdigitated lipid phase

70 kDa heat shock protein Hsp70 (also termed HSP70A1A) is the major stress-inducible member of the HSP70 chaperone family, which is present on the plasma membranes of various tumor cells, but not on the membranes of the corresponding normal cells. The exact mechanisms of Hsp70 anchoring in the membrane and its membrane-related functions are still under debate, since the protein does not contain consensus signal sequence responsible for translocation from the cytosol to the lipid bilayer. The present study was focused on the analysis of the interaction of recombinant human Hsp70 with the model phospholipid membranes. We have confirmed that Hsp70 has strong specificity toward membranes composed of negatively charged phosphatidylserine (PS), compared to neutral phosphatidylcholine membranes. Using differential scanning calorimetry, we have shown for the first time that Hsp70 affects the thermotropic behavior of saturated PS and leads to the interdigitation that controls membrane thickness and rigidity. Hsp70-PS interaction depended on the lipid phase state; the protein stabilized ordered domains enriched with high-melting PS, increasing their area, probably due to formation of quasi-interdigitated phase. Moreover, the ability of Hsp70 to form ion-permeable pores in PS membranes may also be determined by the bilayer thickness. These observations contribute to a better understanding of Hsp70-PS interaction and biological functions of membrane-bound Hsp70 in cancer cells.

Structural and functional complexity of HSP90 in cellular homeostasis and disease

Heat shock protein 90 (HSP90) is a chaperone with vital roles in regulating proteostasis, long recognized for its function in protein folding and maturation. A view is emerging that identifies HSP90 not as one protein that is structurally and functionally homogeneous but, rather, as a protein that is shaped by its environment. In this Review, we discuss evidence of multiple structural forms of HSP90 in health and disease, including homo-oligomers and hetero-oligomers, also termed epichaperomes, and examine the impact of stress, post-translational modifications and co-chaperones on their formation. We describe how these variations influence context-dependent functions of HSP90 as well as its interaction with other chaperones, co-chaperones and proteins, and how this structural complexity of HSP90 impacts and is impacted by its interaction with small molecule modulators. We close by discussing recent developments regarding the use of HSP90 inhibitors in cancer and how our new appreciation of the structural and functional heterogeneity of HSP90 invites a re-evaluation of how we discover and implement HSP90 therapeutics for disease treatment.

Hsp70-Targeting and Size-Tunable Nanoparticles Combine with PD-1 Checkpoint Blockade to Treat Glioma

Invasive glioma usually disrupts the integrity of the blood-brain barrier (BBB), making the delivery of nanodrugs across the BBB possible, but sufficient targeting ability is still avidly needed to improve drug accumulation in glioma. Membrane-bound heat shock protein 70 (Hsp70) is expressed on the membrane of glioma cells rather than adjacent normal cells, therefore it can serve as a specific glioma target. Meanwhile, prolonging the retention in tumors is important for active-targeting nanoparticles to overcome receptor-binding barriers. Herein, the Hsp70-targeting and acid-triggered self-assembled gold nanoparticles (D-A-DA/TPP) are proposed to realize selective delivery of doxorubicin (DOX) to glioma. In the weakly acidic glioma matrix, D-A-DA/TPP formed aggregates to prolong retention, improve receptor-binding efficiency and facilitate acid-responsive DOX release. DOX accumulation in glioma induced immunogenic cell death (ICD) to promote antigen presentation. Meanwhile, combination with the PD-1 checkpoint blockade further activate T cells and provokes robust anti-tumor immunity. The results showed that D-A-DA/TPP can induce more glioma apoptosis. Furthermore, in vivo studies indicated D-A-DA/TPP plus PD-1 checkpoint blockade significantly improved median survival time. This study offeres a potential nanocarrier combining size-tunable strategy with active targeting ability to increase drug enrichment in glioma and synergizes with PD-1 checkpoint blockade to achieve chemo-immunotherapy.

Clinicopathological and prognostic significance of heat shock proteins in hepatocellular carcinoma: a systematic review and meta-analysis

Background

Overexpression of heat shock proteins (HSPs) has been observed in a wide range of human tumors, and there is an increasing evidence demonstrated that HSPs play a key role in tumor progression. Several studies were conducted to explore the clinicopathological characteristics and prognostic value of HSPs in hepatocellular carcinoma (HCC), but the results remain controversial. To address this gap, we conducted a systematic review and meta-analysis.

Methods

The eligible literature was obtained from PubMed, Cochrane library, Web of science, Embase, Chinese National Knowledge Infrastructure and Wan Fang databases. We used the odds ratio (OR) and hazard ratio (HR) as the suitable parameters to assess the clinicopathological features and prognostic value of HSPs in HCC patients.

Results

The meta-analysis results showed that HSPs expression was associated with overall survival (OS) of HCC patients (HR = 1.61, 95%CI = 1.22-2.13, P=0.001, I 2 = 62.7%). In addition, the pooled results suggested that HSPs expression was significantly correlated with tumor differentiation (OR = 1.33, 95%CI = 1.08-1.65, P = 0.907), vascular invasion (OR = 1.31, 95%CI = 1.02-1.69, P = 0.921) and lymphatic metastasis (OR=1.98, 95%CI= 1.70-2.31, P = 0.740). Meanwhile, the subgroup analysis showed a significant correlation between the expression of HSP27 (HR=1.69, 95%CI = 1.24-2.31, P = 0.674) and HSP90α (HR=2.03, 95%CI = 1.73-2.40, P = 0.743) with OS of HCC patients.

Conclusions

Our meta-analysis confirms that HSPs expression is closely associated with a worse prognosis in HCC patients, and may be directly involved in tumor differentiation and distant metastasis. In addition, the subgroup analysis results demonstrate that the expression of HSP27 and HSP90α can be served as potential prognostic predictors of HCC.

Heat shock protein 90 (HSP90) inhibitors in gastrointestinal cancer: where do we currently stand?-A systematic review

PURPOSE

Dysregulated expression of heat shock proteins (HSP) plays a fundamental role in tumor development and progression. Consequently, HSP90 may be an effective tumor target in oncology, including the treatment of gastrointestinal cancers.

METHODS

We carried out a systematic review of data extracted from clinicaltrials.gov and pubmed.gov, which included all studies available until January 1st, 2022. The published data was evaluated using primary and secondary endpoints, particularly with focus on overall survival, progression-free survival, and rate of stable disease.

RESULTS

Twenty trials used HSP90 inhibitors in GI cancers, ranging from phase I to III clinical trials. Most studies assessed HSP90 inhibitors as a second line treatment. Seventeen of the 20 studies were performed prior to 2015 and only few studies have results pending. Several studies were terminated prematurely, due to insufficient efficacy or toxicity. Thus far, the data suggests that HSP90 inhibitor NVP-AUY922 might improve outcome for colorectal cancer and gastrointestinal stromal tumors.

CONCLUSION

It currently remains unclear which subgroup of patients might benefit from HSP90 inhibitors and at what time point these inhibitors may be beneficial. There are only few new or ongoing studies initiated during the last decade.

Heat shock proteins and cancer: The FoxM1 connection

Heat shock proteins (Hsp) and FoxM1 have significant roles in carcinogenesis. According to their relative molecular weight, Hsps are divided into Hsp110, Hsp90, Hsp70, Hsp60, Hsp40, and small Hsps. Hsp70 can play essential functions in cancer initiation and is overexpressed in several human cancers. Hsp70, in combination with cochaperones HIP and HOP, refolds partially denatured proteins and acts as a cochaperone for Hsp90. Also, Hsp70, in combination with BAG3, regulates the FoxM1 signaling pathway. FoxM1 protein is a transcription factor of the Forkhead family that is overexpressed in most human cancers and is involved in many cancers' development features, including proliferation, migration, invasion, angiogenesis, metastasis, and resistance to apoptosis. This review discusses the Hsp70, Hsp90, and FoxM1 structure and function, the known Hsp70 cochaperones, and Hsp70, Hsp90, and FoxM1 inhibitors.

Targeting Heat Shock Proteins in Malignant Brain Tumors: From Basic Research to Clinical Trials

Heat shock proteins (HSPs) are conservative and ubiquitous proteins that are expressed both in prokaryotic and eukaryotic organisms and play an important role in cellular homeostasis, including the regulation of proteostasis, apoptosis, autophagy, maintenance of signal pathways, protection from various stresses (e.g., hypoxia, ionizing radiation, etc.). Therefore, HSPs are highly expressed in tumor cells, including malignant brain tumors, where they also associate with cancer cell invasion, metastasis, and resistance to radiochemotherapy. In the current review, we aimed to assess the diagnostic and prognostic values of HSPs expression in CNS malignancies as well as the novel treatment approaches to modulate the chaperone levels through the application of inhibitors (as monotherapy or in combination with other treatment modalities). Indeed, for several proteins (i.e., HSP10, HSPB1, DNAJC10, HSPA7, HSP90), a direct correlation between the protein level expression and poor overall survival prognosis for patients was demonstrated that provides a possibility to employ them as prognostic markers in neuro-oncology. Although small molecular inhibitors for HSPs, particularly for HSP27, HSP70, and HSP90 families, were studied in various solid and hematological malignancies demonstrating therapeutic potential, still their potential was not yet fully explored in CNS tumors. Some newly synthesized agents (e.g., HSP40/DNAJ inhibitors) have not yet been evaluated in GBM. Nevertheless, reported preclinical studies provide evidence and rationale for the application of HSPs inhibitors for targeting brain tumors.

Overexpression of transmembrane protein 102 implicates poor prognosis and chemoresistance in epithelial ovarian carcinoma patients

Most ovarian cancer patients experience disease recurrence and chemotherapeutic resistance, and the underlying mechanisms are unclear. Identifying relevant pathways could reveal new therapeutic targets. Here we examined expression of transmembrane protein 102 (TMEM102), a biomarker of prognosis and chemoresistance, in epithelial ovarian cancer (EOC), and assessed its role in inhibiting tumor cell apoptosis. We performed qRT-PCR to investigate the association of TMEM102 expression with clinical outcomes in 226 EOC patients. We also conducted in vitro studies to explore possible mechanisms through which TMEM102 may influence chemoresistance, including the effects of downregulating TMEM102 expression with small interfering RNA. Serous and high-grade carcinomas expressed significantly higher TMEM102 than normal ovarian tissues. TMEM102 was also overexpressed in patients with advanced-stage disease and chemoresistance. Reduction of TMEM102 expression by small interfering RNA induced ovarian cancer cell apoptosis after cytotoxic treatment. TMEM102 overexpression enhanced chemoresistance via upregulation of heat shock proteins 27, 60, and 70; and survivin, resulting in decreased cytochrome c in the mitochondria and decreased caspase 9 expression. Our results indicate that TMEM102 overexpression may promote chemoresistance via inhibition of a mitochondria-associated apoptotic pathway.

High mRNA Expression Levels of Heat Shock Protein Family B Member 2 (HSPB2) Are Associated with Breast Cancer Patients’ Relapse and Poor Survival

Small heat shock proteins (sHSPs) are ubiquitous ATP-independent chaperones that contribute to the maintenance of proteome integrity and functionality. Recent evidence suggests that sHSPs are ubiquitously expressed in numerous types of tumors and have been proposed to be implicated in oncogenesis and malignant progression. Heat shock protein family B member 2 (HSPB2) is a member of the sHSPs, which is found to be expressed, among others, in human breast cancer cell lines and constitutes an inhibitor of apical caspase activation in the extrinsic apoptotic pathway. In this study, we investigated the potential prognostic significance of HSPB2 mRNA expression levels in breast cancer, which represents the most frequent malignancy in females and one of the three most common cancer types worldwide. To this end, malignant breast tumors along with paired non-cancerous breast tissue specimens were used. HSPB2 expression levels were quantified in these two cohorts using a sensitive and accurate SYBR green-based quantitative real-time polymerase chain reaction (q-RT-PCR). Extensive biostatistical analyses were performed including Kaplan–Meier and Cox regression survival analyses for the assessment of the results. The significant downregulation of HSPB2 gene expression was revealed in breast tumors compared to their adjacent non-cancerous breast tissues. Notably, high HSPB2 mRNA expression predicts poor disease-free survival and overall survival of breast cancer patients. Multivariate Cox regression analysis revealed that HSPB2 mRNA overexpression is a significant predictor of poor prognosis in breast cancer, independent of other clinicopathological factors. In conclusion, high HSPB2 mRNA expression levels are associated with breast cancer patients’ relapse and poor survival.

Forcing the Antitumor Effects of HSPs Using a Modulated Electric Field

The role of Heat Shock Proteins (HSPs) is a “double-edged sword” with regards to tumors. The location and interactions of HSPs determine their pro- or antitumor activity. The present review includes an overview of the relevant functions of HSPs, which could improve their antitumor activity. Promoting the antitumor processes could assist in the local and systemic management of cancer. We explore the possibility of achieving this by manipulating the electromagnetic interactions within the tumor microenvironment. An appropriate electric field may select and affect the cancer cells using the electric heterogeneity of the tumor tissue. This review describes the method proposed to effect such changes: amplitude-modulated radiofrequency (amRF) applied with a 13.56 MHz carrier frequency. We summarize the preclinical investigations of the amRF on the HSPs in malignant cells. The preclinical studies show the promotion of the expression of HSP70 on the plasma membrane, participating in the immunogenic cell death (ICD) pathway. The sequence of guided molecular changes triggers innate and adaptive immune reactions. The amRF promotes the secretion of HSP70 also in the extracellular matrix. The extracellular HSP70 accompanied by free HMGB1 and membrane-expressed calreticulin (CRT) form damage-associated molecular patterns encouraging the dendritic cells’ maturing for antigen presentation. The process promotes killer T-cells. Clinical results demonstrate the potential of this immune process to trigger a systemic effect. We conclude that the properly applied amRF promotes antitumor HSP activity, and in situ, it could support the tumor-specific immune effects produced locally but acting systemically for disseminated cells and metastatic lesions.

Distinct Cellular Tools of Mild Hyperthermia-Induced Acquired Stress Tolerance in Chinese Hamster Ovary Cells

Mild stress could help cells to survive more severe environmental or pathophysiological conditions. In the current study, we investigated the cellular mechanisms which contribute to the development of stress tolerance upon a prolonged (0–12 h) fever-like (40 °C) or a moderate (42.5 °C) hyperthermia in mammalian Chinese Hamster Ovary (CHO) cells. Our results indicate that mild heat triggers a distinct, dose-dependent remodeling of the cellular lipidome followed by the expression of heat shock proteins only at higher heat dosages. A significant elevation in the relative concentration of saturated membrane lipid species and specific lysophosphatidylinositol and sphingolipid species suggests prompt membrane microdomain reorganization and an overall membrane rigidification in response to the fluidizing heat in a time-dependent manner. RNAseq experiments reveal that mild heat initiates endoplasmic reticulum stress-related signaling cascades resulting in lipid rearrangement and ultimately in an elevated resistance against membrane fluidization by benzyl alcohol. To protect cells against lethal, protein-denaturing high temperatures, the classical heat shock protein response was required. The different layers of stress response elicited by different heat dosages highlight the capability of cells to utilize multiple tools to gain resistance against or to survive lethal stress conditions.

Extracellular HSPs: The Potential Target for Human Disease Therapy

Heat shock proteins (HSPs) are highly conserved stress proteins known as molecular chaperones, which are considered to be cytoplasmic proteins with functions restricted to the intracellular compartment, such as the cytoplasm or cellular organelles. However, an increasing number of observations have shown that HSPs can also be released into the extracellular matrix and can play important roles in the modulation of inflammation and immune responses. Recent studies have demonstrated that extracellular HSPs (eHSPs) were involved in many human diseases, such as cancers, neurodegenerative diseases, and kidney diseases, which are all diseases that are closely linked to inflammation and immunity. In this review, we describe the types of eHSPs, discuss the mechanisms of eHSPs secretion, and then highlight their functions in the modulation of inflammation and immune responses. Finally, we take cancer as an example and discuss the possibility of targeting eHSPs for human disease therapy. A broader understanding of the function of eHSPs in development and progression of human disease is essential for developing new strategies to treat many human diseases that are critically related to inflammation and immunity.

Identifying and Validating of an Autophagy-Related Gene Signature for the Prediction of Early Relapse in Breast Cancer

BACKGROUND

Compelling evidence has demonstrated the pivotal role of autophagy in the prognosis of breast cancer. Breast cancer (BC) patients with early relapse consistently exhibited worse survival.

METHODS

The autophagy-related genes were derived from the Human Autophagy Database (HADb) and high-sequencing data were obtained from The Cancer Genome Atlas (TCGA). Discrepantly expressed autophagy genes (DEAGs) between early relapse and long-term survival groups were performed using the Linear Models for Microarray data (LIMMA) method. Lasso Cox regression analysis was conducted for the selection of the 4-gene autophagy-related gene signature. GSE42568 and GSE21653 databases were enrolled in this study for the external validation of the signature. Then patients were divided into high and low-risk groups based on the specific score formula. GSEA was used to discover the related signaling pathway. The Kaplan-Meier curves and the receiver operating characteristic (ROC) curves were used to evaluate the discrimination and accuracy of the 4-gene signature.

RESULTS

A signature composed of four autophagy-related mRNA including APOL1, HSPA8, SIRT1, and TP73, was identified as significantly associated with the early relapse in BC patients. Time-dependent receiver-operating characteristic at 1 year suggested remarkable accuracy of the signature [area under the curve (AUC = 0.748)]. The risk score model based on the autophagy-related signature showed favorable predicting value in 1-, 2-, and 3-year relapse-free survival (RFS) in training and two validating cohorts. The GSEA displayed gene sets were remarkably enriched in carcinogenic activation pathways and autophagy-related pathways. The nomogram involving three variables (progesterone receptor status, T stage, and 4-gene signature) exhibited relatively good discrimination with a C-index of 0.766.

CONCLUSIONS

Our study establishes an autophagy-related 4-gene signature that can effectively stratify the high-risk and low-risk BC patients for early relapse. Combined with the clinicopathological variables, the signature could significantly help oncologists tailor more efficient treatment strategies for BC patients.

Targeted Hsp70 fluorescence molecular endoscopy detects dysplasia in Barrett's esophagus

PURPOSE

The incidence of esophageal adenocarcinoma (EAC) has been increasing for decades without significant improvements in treatment. Barrett's esophagus (BE) is best established risk factor for EAC, but current surveillance with random biopsies cannot predict progression to cancer in most BE patients due to the low sensitivity and specificity of high-definition white light endoscopy.

METHODS

Here, we evaluated the membrane-bound highly specific Hsp70-specific contrast agent Tumor-Penetrating Peptide (Hsp70-TPP) in guided fluorescence molecular endoscopy biopsy.

RESULTS

Hsp70 was significantly overexpressed as determined by IHC in dysplasia and EAC compared with non-dysplastic BE in patient samples (n = 12) and in high-grade dysplastic lesions in a transgenic (L2-IL1b) mouse model of BE. In time-lapse microscopy, Hsp70-TPP was rapidly taken up and internalized  by human BE dysplastic patient-derived organoids. Flexible fluorescence endoscopy of the BE mouse model allowed a specific detection of Hsp70-TPP-Cy5.5 that corresponded closely with the degree of dysplasia but not BE. Ex vivo application of Hsp70-TPP-Cy5.5 to freshly resected whole human EAC specimens revealed a high (> 4) tumor-to-background ratio and a specific detection of previously undetected tumor infiltrations.

CONCLUSION

In summary, these findings suggest that Hsp70-targeted imaging using fluorescently labeled TPP peptide may improve tumor surveillance in BE patients.

Similarities and Differences of Hsp70, hsc70, Grp78 and Mortalin as Cancer Biomarkers and Drug Targets

Background: Upregulation of Heath Shock Protein 70 (HSP70) chaperones supports cancer cell survival. Their high homology causes a challenge to differentiate them in experimental or prevention and treatment strategies. The objective of this investigation was to determine similarities and differences of Hsp70, hsc70, Grp78 and Mortalin members of the HSP70 family encoded by HSPA1, HSPA8, HSPA5 and HSPA9 genes, respectively. Methods: Literature reviews were conducted using HSPA1, HSPA5, HSPA8 and HSPA9 gene or protein names or synonyms combined with biological or cancer-relevant terms. Ingenuity Pathway Analysis was used to identify and compare profiles of proteins that directly bind individual chaperones and their associated pathways. TCGA data was probed to identify associations of hsc70 with cancer patient survival. ClinicalTrials.gov was used to identify HSP70 family studies. Results: The chaperones have similar protein folding functions. Their different cellular effects are determined by co-chaperones and client proteins combined with their intra- and extra-cellular localizations. Their upregulation is associated with worse patient prognosis in multiple cancers and can stimulate tumor immune responses or drug resistance. Their inhibition selectively kills cancer over healthy cells. Conclusions: Differences in Hsp70, hsc70, Grp78 and mortalin provide opportunities to calibrate HSP70 inhibitors for individual cancers and combination therapies.

Extracellular HSP90 Machineries Build Tumor Microenvironment and Boost Cancer Progression

HSP90 is released by cancer cells in the tumor microenvironment where it associates with different co-chaperones generating complexes with specific functions, ranging from folding and activation of extracellular clients to the stimulation of cell surface receptors. Emerging data indicate that these functions are essential for tumor growth and progression. The understanding of the exact composition of extracellular HSP90 complexes and the molecular mechanisms at the basis of their functions in the tumor microenvironment may represent the first step to design innovative diagnostic tools and new effective therapies. Here we review the impact of extracellular HSP90 complexes on cancer cell signaling and behavior.

The interaction of heat shock proteins with cellular membranes: a historical perspective

The interaction of heat shock proteins (HSP) with cellular membranes has been an enigmatic process, initially observed by morphological studies, inferred during the purification of HSP70s, and confirmed after the detection of these proteins on the surface of cancer cells and their insertion into artificial lipid bilayers. Today, the association of several HSP with lipid membranes is well established. However, the mechanisms for membrane insertion have been elusive. There is conclusive evidence indicating that HSP70s have a great selectivity for negatively charged phospholipids, whereas other HSP have a broader spectrum of lipid specificity. HSP70 also oligomerizes upon membrane insertion, forming ion conductance channels. The functional role of HSP70 lipid interactions appears related to membrane stabilization that may play a role during cell membrane biogenesis. They could also play a role as membrane chaperones as well as during endocytosis, microautophagy, and signal transduction. Moreover, HSP membrane association is a key component in the extracellular export of these proteins. The presence of HSP70 on the surface of cancer cells and its interaction with lysosome membranes have been envisioned as potential therapeutic targets. Thus, the biology and function of HSP membrane association are reaching a new level of excitement. This review is an attempt to preserve the recollection of the pioneering contributions of many investigators that have participated in this endeavor.

Hsp70 in Liquid Biopsies-A Tumor-Specific Biomarker for Detection and Response Monitoring in Cancer

In contrast to normal cells, tumor cells of multiple entities overexpress the Heat shock protein 70 (Hsp70) not only in the cytosol, but also present it on their plasma membrane in a tumor-specific manner. Furthermore, membrane Hsp70-positive tumor cells actively release Hsp70 in small extracellular vesicles with biophysical characteristics of exosomes. Due to conformational changes of Hsp70 in a lipid environment, most commercially available antibodies fail to detect membrane-bound and vesicular Hsp70. To fill this gap and to assess the role of vesicular Hsp70 in circulation as a potential tumor biomarker, we established the novel complete (comp)Hsp70 sandwich ELISA, using two monoclonal antibodies (mAbs), that is able to recognize both free and lipid-associated Hsp70 on the cell surface of viable tumor cells and on small extracellular vesicles. The epitopes of the mAbs cmHsp70.1 (aa 451-461) and cmHsp70.2 (aa 614-623) that are conserved among different species reside in the substrate-binding domain of Hsp70 with measured affinities of 0.42 nM and 0.44 nM, respectively. Validation of the compHsp70 ELISA revealed a high intra- and inter-assay precision, linearity in a concentration range of 1.56 to 25 ng/mL, high recovery rates of spiked liposomal Hsp70 (>84%), comparable values between human serum and plasma samples and no interference by food intake or age of the donors. Hsp70 concentrations in the circulation of patients with glioblastoma, squamous cell or adeno non-small cell lung carcinoma (NSCLC) at diagnosis were significantly higher than those of healthy donors. Hsp70 concentrations dropped concomitantly with a decrease in viable tumor mass upon irradiation of patients with approximately 20 Gy (range 18-22.5 Gy) and after completion of radiotherapy (60-70 Gy). In summary, the compHsp70 ELISA presented herein provides a sensitive and reliable tool for measuring free and vesicular Hsp70 in liquid biopsies of tumor patients, levels of which can be used as a tumor-specific biomarker, for risk assessment (i.e., differentiation of grade III vs. IV adeno NSCLC) and monitoring of therapeutic outcomes.

Beneficial effects of Lactobacillus-fermented black barley on high fat diet-induced fatty liver in rats

A long-term high-fat (HF) diet can cause metabolic disorders, which might induce visceral obesity and ectopic triglyceride storage (e.g., hepatic steatosis), and increase hepatic oxidative stress. Oxidative stress plays a significant role in the development of complications associated with obesity. Fermented whole cereal foods exhibit healthy potential due to their unique phytochemical composition and the presence of probiotics. In the present study, the regular nutrients and phytochemicals of Lactobacillus-fermented black barley (Hordeum distichum L.) were analyzed. Further, the black barley fermentation broth (1 mL per 100 g BW per d, equivalent to 1 mL per kg BW of daily human intake) was administered orally to the rats fed on a high fat diet (HF). The anti-oxidative activity and hepatic metabolic profile of Lactobacillus-fermented black barley were investigated. The results showed that the fermentation processing significantly increased the contents of polyphenols (e.g., ferulic acid, etc.), flavonoids (e.g., flavone, etc.), vitamin B1 and B2, partial mineral elements (e.g., Ca, etc.), and thymine. Furthermore, compared to the HF-fed only rats, fermented black barley treatment significantly increased the activities of SOD (superoxide dismutase) and GSH-PX (glutathione peroxidase), and decreased the level of TBARS (thiobarbituric acid reactive substances) in serum, the levels of TG (triglyceride), TC (total cholesterol), NEFA (non-esterified fatty acid) in the liver, and the levels of TC, NEFA in the adipose tissue. This suggested the beneficial effects of fermented black barley on ameliorating oxidative stress and hepatic steatosis, which could be attributed to its regulatory role in the hepatic metabolism of glycerophospholipids, nicotinate and nicotinamide, glutathione, and nucleotide, and on the expression of genes related to oxidative stress (Heat shock protein 90 and reactive oxygen species modulator 1).

Human heat shock cognate protein (HSC70/HSPA8) interacts with negatively charged phospholipids by a different mechanism than other HSP70s and brings HSP90 into membranes

Heat shock proteins (HSP) are critical elements for the preservation of cellular homeostasis by participating in an array of biological processes. In addition, HSP play an important role in cellular protection from various environmental stresses. HSP are part of a large family of different molecular mass polypeptides, displaying various expression patterns, subcellular localizations, and diversity functions. An unexpected observation was the detection of HSP on the cell surface. Subsequent studies have demonstrated that HSP have the ability to interact and penetrate lipid bilayers by a process initiated by the recognition of phospholipid heads, followed by conformational changes, membrane insertion, and oligomerization. In the present study, we described the interaction of HSPA8 (HSC70), the constitutive cytosolic member of the HSP70 family, with lipid membranes. HSPA8 showed high selectivity for negatively charged phospholipids, such as phosphatidylserine and cardiolipin, and low affinity for phosphatidylcholine. Membrane insertion was mediated by a spontaneous process driven by increases in entropy and diminished by the presence of ADP or ATP. Finally, HSPA8 was capable of driving into the lipid bilayer HSP90 that does not display any lipid biding capacity by itself. This observation suggests that HSPA8 may act as a membrane chaperone.

Inhibition of the Heat Shock Protein A (HSPA) Family Potentiates the Anticancer Effects of Manumycin A

Manumycin A (MA) is a well-tolerated natural antibiotic showing pleiotropic anticancer effects in various preclinical in vitro and in vivo models. Anticancer drugs may themselves act as stressors to induce the cellular adaptive mechanism that can minimize their cytotoxicity. Heat shock proteins (HSPs) as cytoprotective factors can counteract the deleterious effects of various stressful stimuli. In this study, we examined whether the anticancer effects of MA can be counteracted by the mechanism related to HSPs belonging to the HSPA (HSP70) family. We found that MA caused cell type-specific alterations in the levels of HSPAs. These changes included concomitant upregulation of the stress-inducible (HSPA1 and HSPA6) and downregulation of the non-stress-inducible (HSPA2) paralogs. However, neither HSPA1 nor HSPA2 were necessary to provide protection against MA in lung cancer cells. Conversely, the simultaneous repression of several HSPA paralogs using pan-HSPA inhibitors (VER-155008 or JG-98) sensitized cancer cells to MA. We also observed that genetic ablation of the heat shock factor 1 (HSF1) transcription factor, a main transactivator of HSPAs expression, sensitized MCF7 cells to MA treatment. Our study reveals that inhibition of HSF1-mediated heat shock response (HSR) can improve the anticancer effect of MA. These observations suggest that targeting the HSR- or HSPA-mediated adaptive mechanisms may be a promising strategy for further preclinical developments.

Molecular Chaperones and Thyroid Cancer

Thyroid cancers are the most common of the endocrine system malignancies and progress must be made in the areas of differential diagnosis and treatment to improve patient management. Advances in the understanding of carcinogenic mechanisms have occurred in various fronts, including studies of the chaperone system (CS). Components of the CS are found to be quantitatively increased or decreased, and some correlations have been established between the quantitative changes and tumor type, prognosis, and response to treatment. These correlations provide the basis for identifying distinctive patterns useful in differential diagnosis and for planning experiments aiming at elucidating the role of the CS in tumorigenesis. Here, we discuss studies of the CS components in various thyroid cancers (TC). The chaperones belonging to the families of the small heat-shock proteins Hsp70 and Hsp90 and the chaperonin of Group I, Hsp60, have been quantified mostly by immunohistochemistry and Western blot in tumor and normal control tissues and in extracellular vesicles. Distinctive differences were revealed between the various thyroid tumor types. The most frequent finding was an increase in the chaperones, which can be attributed to the augmented need for chaperones the tumor cells have because of their accelerated metabolism, growth, and division rate. Thus, chaperones help the tumor cell rather than protect the patient, exemplifying chaperonopathies by mistake or collaborationism. This highlights the need for research on chaperonotherapy, namely the development of means to eliminate/inhibit pathogenic chaperones.

High Expression of Tomm34 and Its Correlations With Clinicopathology in Oral Squamous Cell Carcinoma

Tomm34, as a member of the outer mitochondrial membrane proteins, is evenly distributed between the cytoplasm and the outer mitochondrial membrane. It is up-regulated in a variety of tumors and correlates with poor prognosis. This study aimed to investigate expression of Tomm34 and its correlations with clinicopathology in oral squamous cell carcinoma (OSCC). Oncomine database and UALCAN database were utilized to predict the expression and prognosis values of Tomm34 in head and neck squamous cell carcinoma (HNSCC). By immunohistochemistry, a retrospective study was performed to verify the bioinformatics results to evaluate the Tomm34 expression and clinicopathological variables in both HPV-positive OSCC and HPV-negative OSCC. Immunohistochemistry of our cohort revealed that 48 cases fulfilled the Tomm34 high expression judgment criteria, and the overall positive rate was 60% (48/80), and 27 cases fulfilled the p16 expression judgment criteria (33.75%, 27/80). The high expression of Tomm34 was closely related with the TNM classification of OSCC (p < 0.01) and tumor size (p < 0.01) both in HPV-negative OSCC and HPV-positive OSCC, while related with lymph node metastasis (p = 0.001) in HPV-negative OSCC and drinking history (p = 0.044) in HPV-positive OSCC. In addition, the Kaplan-Meier curves indicated that higher level of Tomm34 was correlated with poorer overall survival (OS) and disease-free survival (DFS) in HPV-negative OSCC (OS, p = 0.046; DFS, p = 0.020) but not in HPV-positive OSCC (OS, p = 0.824; DFS, p = 0.782). In conclusion, Tomm34 is highly expressed in OSCC and may be a useful factor to provide prognostic information, especially in HPV-negative OSCC group.

Prognostic and Functional Significant of Heat Shock Proteins (HSPs) in Breast Cancer Unveiled by Multi-Omics Approaches

Simple Summary

In this study, we investigated the expression pattern and prognostic significance of the heat shock proteins (HSPs) family members in breast cancer (BC) by using several bioinformatics tools and proteomics investigations. Our results demonstrated that, collectively, HSPs were deregulated in BC, acting as both oncogene and onco-suppressor genes. In particular, two different HSP-clusters were significantly associated with a poor or good prognosis. Interestingly, the HSPs deregulation impacted gene expression and miRNAs regulation that, in turn, affected important biological pathways involved in cell cycle, DNA replication, and receptors-mediated signaling. Finally, the proteomic identification of several HSPs members and isoforms revealed much more complexity of HSPs roles in BC and showed that their expression is quite variable among patients. In conclusion, we elaborated two panels of HSPs that could be further explored as potential biomarkers for BC progression and prognosis.

Abstract

Heat shock proteins (HSPs) are a well-characterized molecular chaperones protein family, classified into six major families, according to their molecular size. A wide range of tumors have been shown to express atypical levels of one or more HSPs, suggesting that they could be used as biomarkers. However, the collective role and the possible coordination of HSP members, as well as the prognostic significance and the functional implications of their deregulated expression in breast cancer (BC) are poorly investigated. Here, we used a systematic multi-omics approach to assess the HSPs expression, the prognostic value, and the underlying mechanisms of tumorigenesis in BC. By using data mining, we showed that several HSPs were deregulated in BC and significantly correlated with a poor or good prognosis. Functional network analysis of HSPs co-expressed genes and miRNAs highlighted their regulatory effects on several biological pathways involved in cancer progression. In particular, these pathways concerned cell cycle and DNA replication for the HSPs co-expressed genes, and miRNAs up-regulated in poor prognosis and Epithelial to Mesenchymal Transition (ETM), as well as receptors-mediated signaling for the HSPs co-expressed genes up-regulated in good prognosis. Furthermore, the proteomic expression of HSPs in a large sample-set of breast cancer tissues revealed much more complexity in their roles in BC and showed that their expression is quite variable among patients and confined into different cellular compartments. In conclusion, integrative analysis of multi-omics data revealed the distinct impact of several HSPs members in BC progression and indicate that collectively they could be useful as biomarkers and therapeutic targets for BC management.

Could Small Heat Shock Protein HSP27 Be a First-Line Target for Preventing Protein Aggregation in Parkinson's Disease?

Small heat shock proteins (HSPs), such as HSP27, are ubiquitously expressed molecular chaperones and are essential for cellular homeostasis. The major functions of HSP27 include chaperoning misfolded or unfolded polypeptides and protecting cells from toxic stress. Dysregulation of stress proteins is associated with many human diseases including neurodegenerative diseases, such as Parkinson's disease (PD). PD is characterized by the presence of aggregates of α-synuclein in the central and peripheral nervous system, which induces the degeneration of dopaminergic neurons in the substantia nigra pars compacta (SNpc) and in the autonomic nervous system. Autonomic dysfunction is an important non-motor phenotype of PD, which includes cardiovascular dysregulation, among others. Nowadays, the therapies for PD focus on dopamine (DA) replacement. However, certain non-motor symptoms with a great impact on quality of life do not respond to dopaminergic drugs; therefore, the development and testing of new treatments for non-motor symptoms of PD remain a priority. Since small HSP27 was shown to prevent α-synuclein aggregation and cytotoxicity, this protein might constitute a suitable target to prevent or delay the motor and non-motor symptoms of PD. In the first part of our review, we focus on the cardiovascular dysregulation observed in PD patients. In the second part, we present data on the possible role of HSP27 in preventing the accumulation of amyloid fibrils and aggregated forms of α-synuclein. We also include our own studies, highlighting the possible protective cardiac effects induced by L-DOPA treatment through the enhancement of HSP27 levels and activity.

Less Can Be More: The Hormesis Theory of Stress Adaptation in the Global Biosphere and Its Implications

A dose-response relationship to stressors, according to the hormesis theory, is characterized by low-dose stimulation and high-dose inhibition. It is non-linear with a low-dose optimum. Stress responses by cells lead to adapted vitality and fitness. Physical stress can be exerted through heat, radiation, or physical exercise. Chemical stressors include reactive species from oxygen (ROS), nitrogen (RNS), and carbon (RCS), carcinogens, elements, such as lithium (Li) and silicon (Si), and metals, such as silver (Ag), cadmium (Cd), and lead (Pb). Anthropogenic chemicals are agrochemicals (phytotoxins, herbicides), industrial chemicals, and pharmaceuticals. Biochemical stress can be exerted through toxins, medical drugs (e.g., cytostatics, psychopharmaceuticals, non-steroidal inhibitors of inflammation), and through fasting (dietary restriction). Key-lock interactions between enzymes and substrates, antigens and antibodies, antigen-presenting cells, and cognate T cells are the basics of biology, biochemistry, and immunology. Their rules do not obey linear dose-response relationships. The review provides examples of biologic stressors: oncolytic viruses (e.g., immuno-virotherapy of cancer) and hormones (e.g., melatonin, stress hormones). Molecular mechanisms of cellular stress adaptation involve the protein quality control system (PQS) and homeostasis of proteasome, endoplasmic reticulum, and mitochondria. Important components are transcription factors (e.g., Nrf2), micro-RNAs, heat shock proteins, ionic calcium, and enzymes (e.g., glutathion redox enzymes, DNA methyltransferases, and DNA repair enzymes). Cellular growth control, intercellular communication, and resistance to stress from microbial infections involve growth factors, cytokines, chemokines, interferons, and their respective receptors. The effects of hormesis during evolution are multifarious: cell protection and survival, evolutionary flexibility, and epigenetic memory. According to the hormesis theory, this is true for the entire biosphere, e.g., archaia, bacteria, fungi, plants, and the animal kingdoms.

Effects of Cell Proteostasis Network on the Survival of SARS-CoV-2

The proteostasis network includes all the factors that control the function of proteins in their native state and minimize their non-functional or harmful reactions. The molecular chaperones, the important mediator in the proteostasis network can be considered as any protein that contributes to proper folding and assembly of other macromolecules, through maturating of unfolded or partially folded macromolecules, refolding of stress-denatured proteins, and modifying oligomeric assembly, otherwise it leads to their proteolytic degradation. Viruses that use the hosts' gene expression tools and protein synthesis apparatus to survive and replicate, are obviously protected by such a host chaperone system. This means that many viruses use members of the hosts' chaperoning system to infect the target cells, replicate, and spread. During viral infection, increase in endoplasmic reticulum (ER) stress due to high expression of viral proteins enhances the level of heat shock proteins (HSPs) and induces cell apoptosis or necrosis. Indeed, evidence suggests that ER stress and the induction of unfolded protein response (UPR) may be a major aspect of the corona-host virus interaction. In addition, several clinical reports have confirmed the autoimmune phenomena in COVID-19-patients, and a strong association between this autoimmunity and severe SARS-CoV-2 infection. Part of such autoimmunity is due to shared epitopes among the virus and host. This article reviews the proteostasis network and its relationship to the immune system in SARS-CoV-2 infection.

The dark-side of the outside: how extracellular heat shock proteins promote cancer

In addition to exerting several essential house-keeping activities in the cell, heat shock proteins (HSPs) are crucial players in a well-structured molecular program activated in response to stressful challenges. Among the different activities carried out by HSPs during emergency, they reach the extracellular milieu, from where they scout the surroundings, regulate extracellular protein activity and send autocrine and paracrine signals. Cancer cells permanently experience stress conditions due to their altered equilibrium and behaviour, and constantly secrete heat shock proteins as a result. Other than supporting anti-tumour immunity, extracellular heat shock proteins (eHSPs), can also exacerbate cancer cell growth and malignancy by sustaining different cancer hallmarks. eHSPs are implicated in extracellular matrix remodelling, resistance to apoptosis, promotion of cell migration and invasion, induction of epithelial to mesenchymal transition, angiogenesis and activation of stromal cells, supporting ultimately, metastasis dissemination. A broader understanding of eHSP activity and contribution to tumour development and progression is leading to new opportunities in the diagnosis and treatment of cancer.

The Mitochondrial Chaperone TRAP1 as a Candidate Target of Oncotherapy

Tumor necrosis factor receptor-associated protein 1 (TRAP1), a member of the heat shock protein 90 (Hsp90) chaperone family, protects cells against oxidative stress and maintains mitochondrial integrity. To date, numerous studies have focused on understanding the relationship between aberrant TRAP1 expression and tumorigenesis. Mitochondrial TRAP1 is a key regulatory factor involved in metabolic reprogramming in tumor cells that favors the metabolic switch of tumor cells toward the Warburg phenotype. In addition, TRAP1 is involved in dual regulation of the mitochondrial apoptotic pathway and exerts an antiapoptotic effect on tumor cells. Furthermore, TRAP1 is involved in many cellular pathways by disrupting the cell cycle, increasing cell motility, and promoting tumor cell invasion and metastasis. Thus, TRAP1 is a very important therapeutic target, and treatment with TRAP1 inhibitors combined with chemotherapeutic agents may become a new therapeutic strategy for cancer. This review discusses the molecular mechanisms by which TRAP1 regulates tumor progression, considers its role in apoptosis, and summarizes recent advances in the development of selective, targeted TRAP1 and Hsp90 inhibitors.

HSP90 inhibition acts synergistically with heat to induce a pro-immunogenic form of cell death in colon cancer cells

BACKGROUND

Sub-ablative heat induces pleiotropic biological effects in cancer cells, activating programmed cell death or survival processes. These processes decide the fate of the heated cell. This study investigates these and assesses whether heat, in combination with HSP90 inhibition, augments cell death and induces a pro-immune phenotype in these cells.

METHODS

HCT116 and HT29 cells were subjected to thermal doses (TID) of 60 and 120CEM43 using a PCR thermal cycler. HSP90 was inhibited with NVP-AUY922. Viability was assessed using the MTT assay. Cellular ATP and HSP70 release were assessed using ATP and Enzyme-linked Immunosorbent assays, respectively. Flow cytometry and immunoblotting were used to study the regulation of biomarkers associated with the heat shock response, the cell cycle, and immunogenic and programmed cell death.

RESULTS

Exposure of HCT116 and HT29 cells to TIDs of 60 and 120CEM43 decreased their viability. In addition, treatment with 120CEM43 increased intracellular HSP70 and the percentage of HCT116/HT29 cells in the G2/M cell cycle phase, ATP release and Calreticulin/HSP70/HSP90 exposure in the plasma membrane, while downregulating CD47 compared to sham-exposed cells. When combined with NVP-AUY922, treatment of HCT116/HT29 cells with 120CEM43 resulted in a synergistic decrease of cell viability associated with the induction of apoptosis. Also, the combined treatments increased Calreticulin exposure, CD47 downregulation, and HSP70 release compared to the sham-exposed cells.

CONCLUSION

Sub-ablative heating can act synergistically with the clinically relevant HSP90 inhibitor NVP-AUY922 to induce a pro-immunogenic form of cell death in colon cancer cells.

Comparative structural insight into prefoldin subunints of archaea and eukaryotes with special emphasis on unexplored prefoldin of Plasmodium falciparum

Prefoldin (PFD) is a heterohexameric molecular chaperone which bind unfolded proteins and subsequently deliver them to a group II chaperonin for correct folding. Although there is structural and functional information available for humans and archaea PFDs, their existence and functions in malaria parasite remains uncharacterized. In the present review, we have collected the available information on prefoldin family members of archaea and humans and attempted to analyze unexplored PFD subunits of Plasmodium falciparum (Pf). Our review enhances the understanding of probable functions, structure and mechanism of substrate binding of Pf prefoldin by comparing with the available information of its homologs in archaea and H. sapiens. Three PfPFD out of six and a Pf prefoldin-like protein are reported to be essential for parasite survival that signifies their importance in malaria parasite biology. Transcriptome analyses suggest that PfPFD subunits are up-regulated at the mRNA level during asexual and sexual stages of parasite life cycle. Our in silico analysis suggested several pivotal proteins like myosin E, cytoskeletal protein (tubulin), merozoite surface protein and ring exported protein 3 as their interacting partners. Based on structural information of archaeal and H. sapiens PFDs, P. falciparum counterparts have been modelled and key interface residues were identified that are critical for oligomerization of PfPFD subunits. We collated information on PFD-substrate binding and PFD-chaperonin interaction in detail to understand the mechanism of substrate delivery in archaea and humans. Overall, our review enables readers to view the PFD family comprehensively. Communicated by Ramaswamy H. SarmaAbbreviations: HSP: Heat shock proteins; CCT: Chaperonin containing TCP-1; PFD: Prefoldin; PFLP: Prefoldin like protein; PfPFD: Plasmodium falciparum prefoldin; Pf: Plasmodium falciparum; H. sapiens: Homo sapiens; M. thermoautotrophicus: Methanobacterium thermoautotrophicus; P. horikoshii: Pyrococcus horikoshii.

Impact of Polyallylamine Hydrochloride on Gene Expression and Karyotypic Stability of Multidrug Resistant Transformed Cells

The synthetic polymer, polyallylamine hydrochloride (PAA), is found in a variety of applications in biotechnology and medicine. It is used in gene and siRNA transfer, to form microcapsules for targeted drug delivery to damaged and tumor cells. Conventional chemotherapy often does not kill all cancer cells and leads to multidrug resistance (MDR). Until recently, studies of the effects of PAA on cells have mainly focused on their morphological and genetic characteristics immediately or several hours after exposure to the polymer. The properties of the cell progeny which survived the sublethal effects of PAA and resumed their proliferation, were not monitored. The present study demonstrated that treatment of immortalized Chinese hamster cells CHLV-79 RJK sensitive (RJK) and resistant (RJKEB) to ethidium bromide (EB) with cytotoxic doses of PAA, selected cells with increased karyotypic instability, were accompanied by changes in the expression of p53 genes c-fos, topo2-α, hsp90, hsc70. These changes did not contribute to the progression of MDR, accompanied by the increased sensitivity of these cells to the toxic effects of doxorubicin (DOX). Our results showed that PAA does not increase the oncogenic potential of immortalized cells and confirmed that it can be used for intracellular drug delivery for anticancer therapy.

Small Heat Shock Proteins in Cancers: Functions and Therapeutic Potential for Cancer Therapy

Small heat shock proteins (sHSPs) are ubiquitous ATP-independent chaperones that play essential roles in response to cellular stresses and protein homeostasis. Investigations of sHSPs reveal that sHSPs are ubiquitously expressed in numerous types of tumors, and their expression is closely associated with cancer progression. sHSPs have been suggested to control a diverse range of cancer functions, including tumorigenesis, cell growth, apoptosis, metastasis, and chemoresistance, as well as regulation of cancer stem cell properties. Recent advances in the field indicate that some sHSPs have been validated as a powerful target in cancer therapy. In this review, we present and highlight current understanding, recent progress, and future challenges of sHSPs in cancer development and therapy.

Heat shock protein 27 immune complex altered signaling and transport (ICAST): Novel mechanisms of attenuating inflammation

Blood levels of heat shock protein (HSP27) and natural IgG auto-antibodies to HSP27 (AAbs) are higher in healthy controls compared to cardiovascular disease patients. Vaccination of mice with recombinant HSP25 (rHSP25, murine ortholog of human rHSP27) increased AAb levels, attenuated atherogenesis and reduced plaque inflammation and cholesterol content. We sought to determine if the HSP27 immune complex (IC) altered MΦ inflammation signaling (Toll Like Receptor 4; TLR4), and scavenger receptors involved in cholesterol uptake (SR-AI, CD-36). Combining a validated polyclonal IgG anti-HSP27 antibody (PAb) with rHSP27 enhanced binding to THP-1 MΦ cell membranes and activation of NF-κB signaling via TLR4, competing away LPS and effecting an anti-inflammatory cytokine profile. Similarly, adding the PAb with rHSP27 enhanced binding to SR-AI and CD-36, as well as lowered oxLDL binding in HEK293 cells separately transfected with SR-AI and CD-36, or THP-1 MΦ. Finally, the PAb enhanced the uptake and internalization of rHSP27 in THP-1 MΦ. Thus, the HSP27 IC potentiates HSP27 cell membrane signaling with receptors involved in modulating inflammation and cholesterol uptake, as well as HSP27 internalization. Going forward, we are focusing on the development of HSP27 Immune Complex Altered Signaling and Transport (ICAST) as a means of modulating inflammation.

The dynamics and role of sphingolipids in eukaryotic organisms upon thermal adaptation

All living beings have an optimal temperature for growth and survival. With the advancement of global warming, the search for understanding adaptive processes to climate changes has gained prominence. In this context, all living beings monitor the external temperature and develop adaptive responses to thermal variations. These responses ultimately change the functioning of the cell and affect the most diverse structures and processes. One of the first structures to detect thermal variations is the plasma membrane, whose constitution allows triggering of intracellular signals that assist in the response to temperature stress. Although studies on this topic have been conducted, the underlying mechanisms of recognizing thermal changes and modifying cellular functioning to adapt to this condition are not fully understood. Recently, many reports have indicated the participation of sphingolipids (SLs), major components of the plasma membrane, in the regulation of the thermal stress response. SLs can structurally reinforce the membrane or/and send signals intracellularly to control numerous cellular processes, such as apoptosis, cytoskeleton polarization, cell cycle arresting and fungal virulence. In this review, we discuss how SLs synthesis changes during both heat and cold stresses, focusing on fungi, plants, animals and human cells. The role of lysophospholipids is also discussed.