Synthetic small interfering RNA targeting heat shock protein 105 induces apoptosis of various cancer cells both in vitro and in vivo

YTHDF1 mediates N-methyl-N-nitrosourea-induced gastric carcinogenesis by controlling HSPH1 translation

YT521-B homology (YTH) domain family (YTHDF) proteins serve as readers that directly recognise m6A modifications. In this study, we aim to probe the role of YTHDF1 in environmental carcinogen-induced malignant transformation of gastric cells and gastric cancer (GC) carcinogenesis. We established a long-term low-dose MNU-induced malignant transformation model in gastric epithelial cells. In vivo and in vitro experiments were conducted to validate the malignant phenotype and characterise the roles of YTHDF1 and its downstream genes in malignant transformation cells. Additionally, we explored downstream m6A modification targets of YTHDF1 using RNA-sequencing, RNA immunoprecipitation, and proteomics analyses, and conducted validation experiments in cell experiments and clinical samples. Long-term low-dose exposure of MNU converted normal Gges-1 cells into malignant cells. YTHDF1 mRNA and protein expression are increased in MNU-induced malignant cells (p<0.001). Meanwhile, YTHDF1 knockdown inhibits the malignant potential of MNU-treated cells (p<0.01). YTHDF1 knockdown specifically suppresses HSPH1 protein, but not RNA levels. RIP-qPCR validates HSPH1 is the target of YTHDF1 (p<0.01). HSPH1 knockdown impairs the malignant potential of MNU-induced transformed cells. The increased expression of the key regulatory factor YTHDF1 in MNU-induced gastric carcinogenesis affects malignant transformation and tumorigenesis by regulating the translation of downstream HSPH1. These findings provide new potential targets for preventing and treating environmental chemical-induced gastric carcinogenesis.

Heat shock protein paradigms in cancer progression: future therapeutic perspectives

Heat-shock proteins (HSPs), also known as stress proteins, are ubiquitously present in all forms of life. They play pivotal roles in protein folding and unfolding, the formation of multiprotein complexes, the transportation and sorting of proteins into their designated subcellular compartments, the regulation of the cell cycle, and signalling processes. These HSPs encompass HSP27, HSP40, HSP70, HSP60, and HSP90, each contributing to various cellular functions. In the context of cancer, HSPs exert influence by either inhibiting or activating diverse signalling pathways, thereby impacting growth, differentiation, and cell division. This article offers an extensive exploration of the functions of HSPs within the realms of pharmacology and cancer biology. HSPs are believed to play substantial roles in the mechanisms underlying the initiation and progression of cancer. They hold promise as valuable clinical markers for cancer diagnosis, potential targets for therapeutic interventions, and indicators of disease progression. In times of cellular stress, HSPs function as molecular chaperones, safeguarding the structural and functional integrity of proteins and aiding in their proper folding. Moreover, HSPs play a crucial role in cancer growth, by regulating processes such as angiogenesis, cell proliferation, migration, invasion, and metastasis.

The Interplay between Heat Shock Proteins and Cancer Pathogenesis: A Novel Strategy for Cancer Therapeutics

Heat shock proteins (HSPs) are developmentally conserved families of protein found in both prokaryotic and eukaryotic organisms. HSPs are engaged in a diverse range of physiological processes, including molecular chaperone activity to assist the initial protein folding or promote the unfolding and refolding of misfolded intermediates to acquire the normal or native conformation and its translocation and prevent protein aggregation as well as in immunity, apoptosis, and autophagy. These molecular chaperonins are classified into various families according to their molecular size or weight, encompassing small HSPs (e.g., HSP10 and HSP27), HSP40, HSP60, HSP70, HSP90, and the category of large HSPs that include HSP100 and ClpB proteins. The overexpression of HSPs is induced to counteract cell stress at elevated levels in a variety of solid tumors, including anticancer chemotherapy, and is closely related to a worse prognosis and therapeutic resistance to cancer cells. HSPs are also involved in anti-apoptotic properties and are associated with processes of cancer progression and development, such as metastasis, invasion, and cell proliferation. This review outlines the previously mentioned HSPs and their significant involvement in diverse mechanisms of tumor advancement and metastasis, as well as their contribution to identifying potential targets for therapeutic interventions.

Functional differences between Hsp105/110 family proteins in cell proliferation, cell division, and drug sensitivity

The mammalian HSP105/110 family consists of four members, including Hsp105 and Apg-1, which function as molecular chaperones. Recently, we reported that Hsp105 knockdown increases sensitivity to the DNA-damaging agent Adriamycin but decreases sensitivity to the microtubule-targeting agent paclitaxel. However, whether the other Hsp105/110 family proteins have the same functional property is unknown. Here, we show that Apg-1 has different roles from Hsp105 in cell proliferation, cell division, and drug sensitivity. We generated the Apg-1-knockdown HeLa S3 cells by lentiviral expression of Apg-1-targeting short hairpin RNA. Knockdown of Apg-1 but not Hsp105 decreased cell proliferation. Apg-1 knockdown increased cell death upon Adriamycin treatment without affecting paclitaxel sensitivity. The cell synchronization experiment suggests that Apg-1 functions in mitotic progression at a different mitotic subphase from Hsp105, which cause difference in paclitaxel sensitivity. Since Apg-1 is overexpressed in certain types of tumors, Apg-1 may become a potential therapeutic target for cancer treatment without causing resistance to the microtubule-targeting agents.

HSP105 expression in cutaneous malignant melanoma: Correlation with clinicopathological characteristics

BACKGROUND

Heat shock proteins can protect against stress-associated cellular challenges, but they can also protect some tumors from human immune system monitoring. Heat shock protein 105 (HSP105/110) is a high molecular weight protein whose expression has been reported in many cancers, but few studies on its role in cutaneous malignant melanoma have been published. In this study, we analyzed the relationship between HSP105 expression and the clinicopathological characteristics of CMM.

METHODS

This retrospective study included 91 patients with CMM. The clinicopathological characteristics of CMM patients, including age, lesion duration, location, pathological classification, Clark's level, Breslow thickness, metastasis and recurrence, were collected. Immunohistochemical staining and Western blot analysis for HSP105 were performed. Pigmented nevi (n = 20) served as a control. The staining intensity and percentage of stained cells were expressed as a histochemical score (HSCORE).

RESULTS

HSP105 was overexpressed in melanoma compared with nevi. Differences in the HSCORE between nevi (HSCORE = 1.05(0.15,1.50)) and CMM (HSCORE = 2.68(1.80,3.60)) were remarkable (P<0.001). Exposed site lesions, recurrent and metastatic lesions, nodular melanoma and lentigo maligna melanoma were closely associated with higher HSP105 expression (P = 0.011, P = 0.001 and P = 0.001, respectively). Moreover, no significant difference was observed in Clark's level, Breslow thickness, or lesion duration (P>0.05).

CONCLUSION

HSP105 is overexpressed in CMM. Higher HSP105 expression in lesions is associated with different clinicopathological variables. HSP105 may be a potential target for the diagnosis, treatment and prognostic prediction of CMM.

Single-Cell Sequencing to Identify Six Heat Shock Protein (HSP) Genes-Mediated Progression Subtypes of Clear Cell Renal Cell Carcinoma

Background

Heat shock proteins (HSPs) are widely involved in tumor occurrence and development and are prognostic markers for multiple tumors. However, the role of HSPs in clear cell renal cell carcinoma (ccRCC) remains unclear.

Methods

We used Cytoscape to identify hub genes in the ccRCC single-cell sequencing data set from the Gene Expression Omnibus (GEO) data repository. We identified subtypes, C1 and C2, of The Cancer Genome Atlas (TCGA) patients based on the expression of hub genes using unsupervised consensus clustering. Principal component analysis (PCA) was used to verify the clustering differences, and Kaplan-Meier (K-M) estimate was used to verify the survival differences between C1 and C2 patients. We used TIMER 2.0 and CIBERSORT to evaluate the immune cell infiltration of HSP genes and C1 and C2 patients. The R package "pRRophetic" was used to evaluate the sensitivity in C1 and C2 patients to the four first-line treatment drugs.

Results

We identified six hub genes (HSP90AA1, HSPH1, HSPA1B, HSPA8, and HSPA1A) encoding HSP, five of which were significantly downregulated in TCGA group, and four had a protective effect on prognosis (p <0.05). Survival analysis showed that C1 patients had a better overall survival (p <0.001). TIMER 2.0 analysis showed that three HSP genes were significantly correlated with the infiltration of CD4+ T cells and CD4+ Th1 cells (|cor|>0.5, p<0.001). CIBERSORT showed significant differences in multiple infiltrating immune cells between C1 and C2 patients. Meanwhile, the expression of PD1 was significantly lower in C1 patients than in C2 patients, and the expression of PDL1 is the another way around. Drug sensitivity analysis showed that C1 patients were more sensitive to sorafenib, pazopanib, and axitinib (p <0.001).

Conclusion

Our research revealed two molecular subtypes of ccRCC based on 6 HSP genes, and revealed significant differences between the two subtypes in terms of clinical prognosis, immune infiltration, and drug sensitivity.

Inhibition of the Human Hsc70 System by Small Ligands as a Potential Anticancer Approach

Simple Summary

High levels of Heat shock proteins (Hsps) in specific cancers are usually linked to a poor prognosis, tumor progression, invasiveness, and resistance to treatment. Chaperone inhibition could therefore be toxic for cancer cells due to their high dependence on chaperone activity to survive. This study shows the potential to repurpose the small chemical compound pinaverium bromide, currently used to treat functional gastrointestinal disorders, as a possible antitumor drug since it displays a marked toxicity against two melanoma cell lines without affecting the viability of fibroblast and primary melanocytes. This compound interacts with structural regions shared by representatives of the Hsp70 and Hsp110 families, inhibiting the substrate remodeling ability of the Hsp70 system in vitro and in a cellular context.

Abstract

Heat shock protein (Hsp) synthesis is upregulated in a wide range of cancers to provide the appropriate environment for tumor progression. The Hsp110 and Hsp70 families have been associated to cancer cell survival and resistance to chemotherapy. In this study, we explore the strategy of drug repurposing to find new Hsp70 and Hsp110 inhibitors that display toxicity against melanoma cancer cells. We found that the hits discovered using Apg2, a human representative of the Hsp110 family, as the initial target bind also to structural regions present in members of the Hsp70 family, and therefore inhibit the remodeling activity of the Hsp70 system. One of these compounds, the spasmolytic agent pinaverium bromide used for functional gastrointestinal disorders, inhibits the intracellular chaperone activity of the Hsp70 system and elicits its cytotoxic activity specifically in two melanoma cell lines by activating apoptosis. Docking and molecular dynamics simulations indicate that this compound interacts with regions located in the nucleotide-binding domain and the linker of the chaperones, modulating their ATPase activity. Thus, repurposing of pinaverium bromide for cancer treatment appears as a promising novel therapeutic approach.

Dual roles of HSP70 chaperone HSPA1 in quality control of nascent and newly synthesized proteins

Exposure to heat stress triggers a well‐defined acute response marked by HSF1‐dependent transcriptional upregulation of heat shock proteins. Cells allowed to recover acquire thermotolerance, but this adaptation is poorly understood. By quantitative proteomics, we discovered selective upregulation of HSP70‐family chaperone HSPA1 and its co‐factors, HSPH1 and DNAJB1, in MCF7 breast cancer cells acquiring thermotolerance. HSPA1 was found to have dual function during heat stress response: (i) During acute stress, it promotes the recruitment of the 26S proteasome to translating ribosomes, thus poising cells for rapid protein degradation and resumption of protein synthesis upon recovery; (ii) during thermotolerance, HSPA1 together with HSPH1 maintains ubiquitylated nascent/newly synthesized proteins in a soluble state required for their efficient proteasomal clearance. Consistently, deletion of HSPH1 impedes thermotolerance and esophageal tumor growth in mice, thus providing a potential explanation for the poor prognosis of digestive tract cancers with high HSPH1 and nominating HSPH1 as a cancer drug target. We propose dual roles of HSPA1 either alone or in complex with HSPH1 and DNAJB1 in promoting quality control of nascent/newly synthesized proteins and cellular thermotolerance.

The Role of Non-Canonical Hsp70s (Hsp110/Grp170) in Cancer

Although cancers account for over 16% of all global deaths annually, at present, no reliable therapies exist for most types of the disease. As protein folding facilitators, heat shock proteins (Hsps) play an important role in cancer development. Not surprisingly, Hsps are among leading anticancer drug targets. Generally, Hsp70s are divided into two main subtypes: canonical Hsp70 (Escherichia coli Hsp70/DnaK homologues) and the non-canonical (Hsp110 and Grp170) members. These two main Hsp70 groups are delineated from each other by distinct structural and functional specifications. Non-canonical Hsp70s are considered as holdase chaperones, while canonical Hsp70s are refoldases. This unique characteristic feature is mirrored by the distinct structural features of these two groups of chaperones. Hsp110/Grp170 members are larger as they possess an extended acidic insertion in their substrate binding domains. While the role of canonical Hsp70s in cancer has received a fair share of attention, the roles of non-canonical Hsp70s in cancer development has received less attention in comparison. In the current review, we discuss the structure-function features of non-canonical Hsp70s members and how these features impact their role in cancer development. We further mapped out their interactome and discussed the prospects of targeting these proteins in cancer therapy.

HSP110 expression in canine mammary gland tumor and its correlation with histopathological classification and grade

Heat shock proteins (HSPs) play critical roles as molecular chaperones, thereby promoting cellular homeostasis. HSPs are overexpressed in many types of human tumors and their serum concentration is elevated in cancer patients. Recent studies have suggested that HSPs may promote tumorigenesis via interactions with tumor-related proteins. There are only a few studies that address the expression of HSPs in canine tumors. In our previous study, we identified elevated levels of HSP110 expression in canine mammary gland tumors (cMGTs). In this study, we examined both serum concentrations and tissue expression of HSP110 in dogs with cMGT. We found that serum HSP110 concentrations were not significantly different in a comparison between dogs with cMGT (3.44 ± 1.27 μg/mL) and healthy controls (3.23 ± 1.18 μg/mL). By contrast, significant differences in levels of HSP110 expression were identified in comparisons between simple carcinoma and benign mixed tumor (p = 0.001), simple carcinoma and non-neoplastic lesions (p < 0.001), complex carcinoma and benign mixed tumor (p = 0.015), complex carcinoma and non-neoplastic lesions (p < 0.001), simple adenoma and benign mixed tumor (p = 0.041), and simple adenoma and non-neoplastic lesions (p = 0.007). Similarly, significantly different levels of HSP110 expression were identified when comparing grade Ⅲ with non-neoplastic lesion (p = 0.026), grade Ⅱ with benign tumor (p = 0.015), grade Ⅱ with non-neoplastic lesion (p < 0.001), and grade Ⅰ with non-neoplastic lesion (p < 0.001). Taken together, our results indicate that expression of HSP110 correlates with the malignancy in this cohort of dogs diagnosed with cMGT. These findings also suggest that HSP110 is associated with tumorigenesis and the relative malignancy of cMGT.

HSP105 expression in oral squamous cell carcinoma: Correlation with clinicopathological features and outcomes

BACKGROUND

Heat shock proteins (HSPs) are released in response to stress situations, such as heat, inflammation, and infection. They are also involved in the tumor cell proliferation and prevention of apoptosis. Heat shock protein 105 (Hsp105/110) is a high-molecular-weight protein, which has been reported in many cancer types but few studies have been carried out on oral squamous cell carcinoma (OSCC). In the current study, we have focused on HSP105 expression on OSCC and evaluated their correlation with tumor clinicopathological parameters and patients' survival.

METHODS

A retrospective study included 70 patients with OSCC of which 50 patients (71.4%) were male and 20 (28.6%) were female. The patient's information, including age, location, TNM stage, histological grade, regional metastasis, recurrence, and survival, were collected. Immunohistochemical staining for HSP105 was performed. The healthy oral mucosa (n = 10) was used as a control. The staining intensity and percentage of stained cells were semi-quantitatively evaluated, and HSP105 expression was correlated with tumor clinicopathological features and patient survival.

RESULTS

Statistical analysis for HSP105 showed that there was no significant correlation with tumor clinicopathological features. However, HSP105 overexpression was associated with a decrease in the duration of patients' survival (P = .042).

CONCLUSION

This result suggests that the increased expression of the HSP105 in the OSCC could be a prognostic factor for malignancy.

Hsp105α suppresses Adriamycin-induced cell death via nuclear localization signal-dependent nuclear accumulation

Heat shock protein 105 (Hsp105) is a molecular chaperone, and the isoforms Hsp105α and Hsp105β exhibit distinct functions with different subcellular localizations. Hsp105β localizes in the nucleus and induces the expression of the major heat shock protein Hsp70, whereas cytoplasmic Hsp105α is less effective in inducing Hsp70 expression. Hsp105 shuttles between the cytoplasm and the nucleus; the subcellular localization is governed by the relative activities of the nuclear localization signal (NLS) and nuclear export signal (NES). Here, we show that nuclear accumulation of Hsp105α but not Hsp105β is involved in Adriamycin (ADR) sensitivity. Knockdown of Hsp105α induces cell death at low ADR concentration, at which ADR is less effective in inducing cell death in the presence of Hsp105α. Of note, Hsp105 is localized in the nucleus under these conditions, even though Hsp105β is not expressed, indicating that Hsp105α accumulates in the nucleus in response to ADR treatment. The exogenously expressed Hsp105α but not its NLS mutant localizes in the nucleus of ADR-treated cells. In addition, the expression level of the nuclear export protein chromosomal maintenance 1 (CRM1) was decreased by ADR treatment of cells, and CRM1 knockdown caused nuclear accumulation of Hsp105α both in the presence and absence of ADR. These results indicating that Hsp105α accumulates in the nucleus in a manner dependent on the NLS activity via the suppression of nuclear export. Our findings suggest a role of nuclear Hsp105α in the sensitivity against DNA-damaging agents in tumor cells.

Heat shock protein 105 peptide vaccine could induce antitumor immune reactions in a phase I clinical trial

Heat shock protein 105 (HSP105) is overexpressed in many cancers, including colorectal cancer (CRC) and esophageal cancer (EC). We carried out a phase I clinical trial of HLA-A24- and HLA-A2-restricted HSP105 peptide vaccines in patients with CRC or EC. In this additional study of the trial, we examined the immunological efficacy of the novel vaccine. Thirty patients with advanced CRC or EC underwent HSP105 peptide vaccination. Immunological responses were evaluated by ex vivo and in vitro γ-interferon enzyme-linked immunospot assays and their correlation with patients' prognosis was analyzed. The HSP105 peptide vaccines induced peptide-specific CTLs in 15 of 30 patients. Among HLA-A24 patients (n = 15), 7 showed induction of CTLs only ex vivo, whereas among HLA-A2 patients (n = 15), 4 showed the induction ex vivo and 6 in vitro. Heat shock protein 105-specific CTL induction correlated with suppression of cancer progression and was revealed as a potential predictive biomarker for progression-free survival (P = .008; hazard ratio = 3.03; 95% confidence interval, 1.34-6.85) and overall survival (P = .025; hazard ratio = 2.72; 95% confidence interval, 1.13-6.52). Production of cytokines by HSP105 peptide-specific CTLs was observed at the injection sites (skin) and tumor tissues, suggesting that HSP105-specific CTLs not only accumulated at vaccination sites but also infiltrated tumors. Furthermore, we established 2 HSP105 peptide-specific CTL clones, which showed HSP105-specific cytokine secretion and cytotoxicity. Our results suggest that the HSP105 peptide vaccine could induce immunological effects in cancer patients and improve their prognosis.

iTRAQ-based proteomics analysis reveals the deregulated proteins related to liver toxicity induced by melamine with or without cyanuric acid in mice

The administration of melamine alone or its combination with cyanuric acid was shown to have certain liver toxicity. However, the injury mechanism of melamine-related toxicity to liver remains poorly understood. In the present study, we investigated the deregulated proteins related to liver toxicity induced by melamine with or without cyanuric acid in mice using iTRAQ quantitative proteomics technique. A total of 166 proteins were significantly changed by the melamine treatment, of which, 36 proteins were up-regulated and 130 proteins were down-regulated. Whereas, 242 proteins were significantly changed by the combined treatment of melamine and cyanuric acid, of which 81 proteins were up-regulated and 161 proteins were down-regulated. The enriched analysis of GO terms and KEGG pathway on the altered proteins showed that both enriched main GO terms and KEGG pathways appear to be different between the two kinds of treatments: melamine and mixture of melamine and cyanuric acid. Based on western blotting technique, it was confirmed that the expression of three proteins: heat shock protein 70 (HSP70), protein disulphide isomerase 6 (PDIA6) and heat shock 70 kDa protein 4-like (HSPA4L) were agreement with the findings in iTRAQ-Based quantitative analysis. These identified proteins might participate in the regulation of a wide range of biological processes, such as immune and inflammatory function, unfolded proteins response in endoplasmic reticulum, DNA damage, and the apoptosis of liver cells. These results from this study provide a new way to gain insight into the mechanisms of melamine-related toxicity to liver in animals.

Rosmarinic acid and siRNA combined therapy represses Hsp27 (HSPB1) expression and induces apoptosis in human glioma cells

High expression of Hsp27 in glioma cells has been closely associated with tumor cell proliferation and apoptosis inhibition. The aim of the present study was to asses the effects of rosmarinic acid (RA) on Hsp27 expression and apoptosis in non-transfected and transfected human U-87 MG cells. The effect of rosmarinic acid was compared to quercetin, which is known to be a good Hsp27 inhibitor. In order to block the expression of Hsp27 gene (HSPB1), transfection with specific siRNAs was performed. Western blotting technique was used to assess the Hsp27 expression, and caspase-3 colorimetric activity assay was performed to determine apoptosis induction. According to the results, it was found that RA and quercetin effectively silenced Hsp27 and both agents induced apoptosis by activating the caspase-3 pathway. Eighty and 215 μM RA decreased the level of Hsp27 by 28.8 and 46.7% and induced apoptosis by 30 and 54%, respectively. For the first time, we reported that rosmarinic acid has the ability to trigger caspase-3 induced apoptosis in human glioma cells. As a result of siRNA transfection, the Hsp27 gene was silenced by ~ 50% but did not cause a statistically significant change in caspase-3 activation. It was also observed that apoptosis was induced at a higher level as a result of Hsp27 siRNA and subsequent quercetin or RA treatment. siRNA transfection and 215 μM RA treatment suppressed Hsp27 expression level by 90.5% and increased caspase-3 activity by 58%. Herein, we demonstrated that RA administered with siRNA seems to be a potent combination for glioblastoma therapy.

Cerebrospinal Fluid Proteins Identification Facilitates the Differential Diagnosis of Central Nervous System Diffuse Large B Cell Lymphoma

Background: Diagnosis of central nervous system (CNS) lymphoma remains a challenge. This study aimed to identify cerebrospinal fluid (CSF) proteins that distinguish patients with and without CNS lymphoma. Methods: We used one-dimensional SDS-polyacrylamide gel electrophoresis coupled with liquid chromatography- electrospray ionization-quadrupole-time of flight-mass spectrometry (LC-ESI-Q-TOF MS) to identify CSF proteins in CNS diffuse large B cell lymphoma (DLBCL) patients and controls. Results: Approximately 166 CSF proteins were identified, 12 for the first time in the CSF of lymphoma patients. Three proteins with significantly increased expression in CNS lymphoma patients compared with controls - haemopexin, apolipoprotein A1, and transferrin were verified by immunohistochemistry, and found to be strongly expressed in CNS DLBCL and nodal DLBCL. These proteins were found to be localized in the cytoplasm of a human DLBCL cell line by indirect immunofluorescence. ELISA confirmed expression at higher concentrations in the CSF of CNS lymphoma patients. CSF haemopexin, apolipoprotein A1, and transferrin concentrations were detected in CNS lymphoma patients and had diagnostic sensitivities of 80%, 83%, and 70%, and specificities of 75%, 89%, and 90%, respectively. Conclusion: Our study suggests that CSF proteins may be potential diagnostic biomarker for CNS lymphoma, especially for patients in which imaging and cytology do not provide a clear diagnosis.

Targeting Heat Shock Proteins in Cancer: A Promising Therapeutic Approach

Heat shock proteins (HSPs) are a large family of chaperones that are involved in protein folding and maturation of a variety of "client" proteins protecting them from degradation, oxidative stress, hypoxia, and thermal stress. Hence, they are significant regulators of cellular proliferation, differentiation and strongly implicated in the molecular orchestration of cancer development and progression as many of their clients are well established oncoproteins in multiple tumor types. Interestingly, tumor cells are more HSP chaperonage-dependent than normal cells for proliferation and survival because the oncoproteins in cancer cells are often misfolded and require augmented chaperonage activity for correction. This led to the development of several inhibitors of HSP90 and other HSPs that have shown promise both preclinically and clinically in the treatment of cancer. In this article, we comprehensively review the roles of some of the important HSPs in cancer, and how targeting them could be efficacious, especially when traditional cancer therapies fail.

Nuclear heat shock protein 110 expression is associated with poor prognosis and chemotherapy resistance in gastric cancer

Heat shock protein (HSP) expression is induced by the exposure to stress, such as fever, oxidative stress, chemical exposure, and irradiation. In cancer, HSP promotes the survival of malignant cells by inhibiting the induction of apoptosis. In colorectal cancer, a loss-of-function mutation of HSP110 (HSP110ΔE9) has been identified. HSP110ΔE9 inhibits the nuclear translocation of wild-type HSP110, which is important for its chaperone activity and anti-apoptotic effects. The patients carrying HSP110ΔE9 mutation exhibit high sensitivity to anticancer agents, such as oxaliplatin and 5-fluorouracil. There is still insufficient information about HSP110 localization, the clinicopathological significance of HSP110 expression, and its association with chemotherapy resistance in gastric cancer. Here, we found that high nuclear expression of HSP110 in gastric cancer tissues is associated with cancer progression, poor prognosis, and recurrence after adjuvant chemotherapy. In vitro results showed that HSP110 suppression increases the sensitivity to 5-fluorouracil and cisplatin of human gastric cancer cell lines. Our results suggest that nuclear HSP110 may be a new drug sensitivity marker for gastric cancer and a potential molecular therapeutic target for the treatment of gastric cancer patients with acquired anticancer drug resistance.

Heat Shock Proteins and Cancer

Heat shock proteins (HSPs) constitute a large family of proteins involved in protein folding and maturation whose expression is induced by heat shock or other stressors. The major groups are classified based on their molecular weights and include HSP27, HSP40, HSP60, HSP70, HSP90, and large HSPs. HSPs play a significant role in cellular proliferation, differentiation, and carcinogenesis. In this article we comprehensively review the roles of major HSPs in cancer biology and pharmacology. HSPs are thought to play significant roles in the molecular mechanisms leading to cancer development and metastasis. HSPs may also have potential clinical uses as biomarkers for cancer diagnosis, for assessing disease progression, or as therapeutic targets for cancer therapy.

Unfolding the Role of Large Heat Shock Proteins: New Insights and Therapeutic Implications

Heat shock proteins (HSPs) of eukaryotes are evolutionarily conserved molecules present in all the major intracellular organelles. They mainly function as molecular chaperones and participate in maintenance of protein homeostasis in physiological state and under stressful conditions. Despite their relative abundance, the large HSPs, i.e., Hsp110 and glucose-regulated protein 170 (Grp170), have received less attention compared to other conventional HSPs. These proteins are distantly related to the Hsp70 and belong to Hsp70 superfamily. Increased sizes of Hsp110 and Grp170, due to the presence of a loop structure, result in their exceptional capability in binding to polypeptide substrates or non-protein ligands, such as pathogen-associated molecules. These interactions that occur in the extracellular environment during tissue injury or microbial infection may lead to amplification of an immune response engaging both innate and adaptive immune components. Here, we review the current advances in understanding these large HSPs as molecular chaperones in proteostasis control and immune modulation as well as their therapeutic implications in treatment of cancer and neurodegeneration. Given their unique immunoregulatory activities, we also discuss the emerging evidence of their potential involvement in inflammatory and immune-related diseases.

Effects of High Hydrostatic Pressure on Expression Profiles of In Vitro Produced Vitrified Bovine Blastocysts

High hydrostatic pressure (HHP) has been used to pre-condition embryos before essential, yet potentially detrimental procedures such as cryopreservation. However, the mechanisms for HHP are poorly understood. We treated bovine blastocysts with three different HHP (40, 60 and 80 MPa) in combination with three recovery periods (0, 1 h, 2 h post HHP). Re-expansion rates were significantly higher at 40 and 60 but lower at 80 MPa after vitrification-warming in the treated groups than controls. Microarray analysis revealed 399 differentially expressed transcripts, representing 254 unique genes, among different groups. Gene ontology analysis indicated that HHP at 40 and 60 MPa promoted embryo competence through down-regulation of genes in cell death and apoptosis, and up-regulation of genes in RNA processing, cellular growth and proliferation. In contrast, 80 MPa up-regulated genes in apoptosis, and down-regulated protein folding and cell cycle-related genes. Moreover, gene expression was also influenced by the length of the recovery time after HHP. The significantly over-represented categories were apoptosis and cell death in the 1 h group, and protein folding, response to unfolded protein and cell cycle in the 2 h group compared to 0 h. Taken together, HHP promotes competence of vitrified bovine blastocysts through modest transcriptional changes.

HSP105 recruits protein phosphatase 2A to dephosphorylate β-catenin

The Wnt/β-catenin pathway causes accumulation of β-catenin in the cytoplasm and its subsequent translocation into the nucleus to initiate the transcription of the target genes. Without Wnt stimulation, β-catenin forms a complex with axin (axis inhibitor), adenomatous polyposis coli (APC), casein kinase 1α (CK1α), and glycogen synthase kinase 3β (GSK3β) and undergoes phosphorylation-dependent ubiquitination. Phosphatases, such as protein phosphatase 2A (PP2A), interestingly, also are components of this degradation complex; therefore, a balance must be reached between phosphorylation and dephosphorylation. How this balance is regulated is largely unknown. Here we show that a heat shock protein, HSP105, is a previously unidentified component of the β-catenin degradation complex. HSP105 is required for Wnt signaling, since depletion of HSP105 compromises β-catenin accumulation and target gene transcription upon Wnt stimulation. Mechanistically, HSP105 depletion disrupts the integration of PP2A into the β-catenin degradation complex, favoring the hyperphosphorylation and degradation of β-catenin. HSP105 is overexpressed in many types of tumors, correlating with increased nuclear β-catenin protein levels and Wnt target gene upregulation. Furthermore, overexpression of HSP105 is a prognostic biomarker that correlates with poor overall survival in breast cancer patients as well as melanoma patients participating in the BRIM2 clinical study.

HSPH1 inhibition downregulates Bcl-6 and c-Myc and hampers the growth of human aggressive B-cell non-Hodgkin lymphoma

We have shown that human B-cell non-Hodgkin lymphomas (B-NHLs) express heat shock protein (HSP)H1/105 in function of their aggressiveness. Here, we now clarify its role as a functional B-NHL target by testing the hypothesis that it promotes the stabilization of key lymphoma oncoproteins. HSPH1 silencing in 4 models of aggressive B-NHLs was paralleled by Bcl-6 and c-Myc downregulation. In vitro and in vivo analysis of HSPH1-silenced Namalwa cells showed that this effect was associated with a significant growth delay and the loss of tumorigenicity when 10(4) cells were injected into mice. Interestingly, we found that HSPH1 physically interacts with c-Myc and Bcl-6 in both Namalwa cells and primary aggressive B-NHLs. Accordingly, expression of HSPH1 and either c-Myc or Bcl-6 positively correlated in these diseases. Our study indicates that HSPH1 concurrently favors the expression of 2 key lymphoma oncoproteins, thus confirming its candidacy as a valuable therapeutic target of aggressive B-NHLs.

A microRNA-27a mimic sensitizes human oral squamous cell carcinoma HSC-4 cells to hyperthermia through downregulation of Hsp110 and Hsp90

Hyperthermia (HT) is an important modality in cancer treatment; however, the acquisition of thermal resistance in cancer cells due to the elevation of heat shock proteins (HSPs) makes HT less effective. Accumulating evidence suggests that microRNAs (miRNAs) play an important role in regulating cellular stress sensitivities, such as drug sensitivity and radio-sensitivity, in cancer cells. However, few studies have investigated the involvement of miRNAs in thermal sensitivity. The aim of this study was thus to investigate the contribution of miRNAs to the thermal sensitivity of human oral squamous cell carcinoma (OSCC) cells. When the HSC-2, HSC-3 and HSC-4 OSCC cell lines were treated with HT at 44˚C for 60 min, a significant increase in cell death was observed in HSC-2 and HSC-3 cells but not HSC-4 cells, suggesting that HSC-4 cells were thermally resistant under the present experimental conditions. Moreover, the expression levels of HSPs were most elevated in HSC-4 cells. When the basal expression levels of miRNAs were monitored using two different microarray systems in thermal-sensitive HSC-2 and HSC-3 cells and thermal-resistant HSC-4 cells, five miRNAs that were differentially expressed were identified. Among these miRNAs, the expression level of miR-27a in HSC-4 cells was markedly reducec compared to the expression levels in HSC-2 and HSC-3 cells. Interestingly, treatment of HSC-4 cells with a miR-27a mimic oligonucleotide significantly enhanced HT-induced cell death. Furthermore, the miR-27a mimic oligonucleotide suppressed the elevation of the expression of Hsp90 and Hsp110 in HSC-4 cells, suggesting that these HSPs may be involved in a mechanism of thermal resistance. From these findings, we concluded that in OSCC cells, miR-27a may contribute to thermal sensitivity by modulating the HSP expression.

Identification of HLA-A2 or HLA-A24-restricted CTL epitopes for potential HSP105-targeted immunotherapy in colorectal cancer

We previously reported that heat shock protein 105 (HSP105) is overexpressed in a variety of human cancers, including colorectal, pancreatic and esophageal cancer and has proven to be a novel biomarker for the immunohistochemical detection of these cancers. In the present study, we used HLA-transgenic mice (Tgm) and the peripheral blood mononuclear cells (PBMCs) of colorectal cancer patients to identify HLA-A2 and HLA-A24-restricted HSP105 epitopes, as a means of expanding the application of HSP105-based immunotherapy to HLA-A2- or HLA-A24-positive cancer patients. In addition, we investigated by ex vivo IFN-γ ELISPOT assay whether the HSP105-derived peptide of cytotoxic T cells (CTLs) exists in PBMCs of pre-surgical colorectal cancer patients. We found that four peptides, HSP105 A2-7 (RLMNDMTAV), HSP105 A2-12 (KLMSSNSTDL), HSP105 A24-1 (NYGIYKQDL) and HSP105 A24-7 (EYVYEFRDKL), are potential HLA-A2 or HLA-A24-restricted CTL HSP105-derived epitopes. HSP105-specific IFN-γ-secreting T cells were detected in 14 of 21 pre-surgical patients with colorectal cancer in response to stimulation with these four peptides. Our study raises the possibility that these HSP105 peptides are applicable to cancer immunotherapy in patients with HSP105-expressing cancer, particularly colorectal cancer.

Enhanced expression of transferrin receptor 1 contributes to oncogenic signalling by sphingosine kinase 1

Sphingosine kinase 1 (SK1) is a lipid kinase that catalyses the formation of sphingosine-1-phosphate (S1P). Considerable evidence has implicated elevated cellular SK1 in tumour development, progression and disease severity. In particular, SK1 has been shown to enhance cell survival and proliferation and induce neoplastic transformation. Although S1P has been found to have both cell-surface G-protein-coupled receptors and intracellular targets, the specific downstream pathways mediating oncogenic signalling by SK1 remain poorly defined. Here, using a gene expression array approach, we have demonstrated a novel mechanism whereby SK1 regulates cell survival, proliferation and neoplastic transformation through enhancing expression of transferrin receptor 1 (TFR1). We showed that elevated levels of SK1 enhanced total as well as cell-surface TFR1 expression, resulting in increased transferrin uptake into cells. Notably, we also found that SK1 activation and localization to the plasma membrane, which are critical for its oncogenic effects, are necessary for regulation of TFR1 expression specifically through engagement of the S1P G-protein coupled receptor, S1P2. Furthermore, we showed that blocking TFR1 function with a neutralizing antibody inhibits SK1-induced cell proliferation, survival and neoplastic transformation of NIH3T3 fibroblasts. Similar effects were observed following antagonism of S1P2. Together these findings suggest that TFR1 has an important role in SK1-mediated oncogenesis.

Identification of tumor antigens that elicit a humoral immune response in the sera of Chinese esophageal squamous cell carcinoma patients by modified serological proteome analysis

Our aim was to identify novel tumor-associated antigens from the esophageal squamous cell carcinoma (ESCC) cell line EC0156, and related autoantibodies in sera from patients with ESCC. We used modified serological proteome analysis, involving one- and two-dimensional electrophoresis, Western blot, and MALDI-TOF/TOF-MS to identify 6 ESCC-associated antigens. From these, 105 kDa heat shock protein (HSP105) and triosephosphate isomerase (TIM) were further evaluated and we determined they could induce autoantibody responses in ESCC sera and are highly expressed in ESCC tissues. Anti-HSP105 and anti-TIM autoantibodies were found in 39.1% (18/46) and 34.8% (16/46) of patients with ESCC, respectively, but only in two controls. A receiver operating characteristic curve constructed with HSP105 and TIM gave a sensitivity of 54.3% and 95% (38/40) specificity in discriminating ESCC from matched controls. Interestingly, we found that autoantibodies against TIM in ESCC serum mainly reacted with glycosylated but not deglycosylated TIM. The preliminary results suggest the potential utility of screening autoantibodies in sera for use as biomarkers for cancer diagnosis.

High expression of heat shock protein 105 predicts a favorable prognosis for patients with urinary bladder cancer treated with radical cystectomy

Heat shock protein 105 (Hsp105) is one of the cancer/testis antigens, which is overexpressed in a variety of cancer cells, including urinary bladder cancer, and has been investigated as a target molecule for immunotherapy due to its immunogenicity. In this study, we assessed the expression of Hsp105 in primary bladder cancer samples from 84 patients treated with radical cystectomy, using immunohistochemical analysis, and investigated its correlation with clinicopathological characteristics and cancer-specific survival. The immunoreactivity of Hsp105 expression was evaluated as a score of 0-3, according to the intensity of the signal. The Hsp105 expression was high (score 2 or 3) in 31 cases and low (score 0 or 1) in 53 cases; however, it was not significantly correlated with age, nuclear grade, pathological tumor stage and previous intravesical Bacillus Calmette-Guérin immunotherapy. Female gender, lymphovascular invasion and lymph node metastasis were associated with low Hsp105 scores, although the differences were not statistically significant (P=0.071, 0.061 and 0.175, respectively). However, a high Hsp105 score was significantly associated with a favorable prognosis (P=0.017) and was identified as an independent prognostic factor by multivariate analysis (P=0.032; hazard ratio, 2.34). These findings suggested that the expression of Hsp105 may be a novel indicator of a favorable prognosis in bladder cancer.

Hsp70 protein complexes as drug targets

Heat shock protein 70 (Hsp70) plays critical roles in proteostasis and is an emerging target for multiple diseases. However, competitive inhibition of the enzymatic activity of Hsp70 has proven challenging and, in some cases, may not be the most productive way to redirect Hsp70 function. Another approach is to inhibit Hsp70's interactions with important co-chaperones, such as J proteins, nucleotide exchange factors (NEFs) and tetratricopeptide repeat (TPR) domain-containing proteins. These co-chaperones normally bind Hsp70 and guide its many diverse cellular activities. Complexes between Hsp70 and co-chaperones have been shown to have specific functions, including roles in pro-folding, pro-degradation and pro-trafficking pathways. Thus, a promising strategy may be to block protein- protein interactions between Hsp70 and its co-chaperones or to target allosteric sites that disrupt these contacts. Such an approach might shift the balance of Hsp70 complexes and re-shape the proteome and it has the potential to restore healthy proteostasis. In this review, we discuss specific challenges and opportunities related to these goals. By pursuing Hsp70 complexes as drug targets, we might not only develop new leads for therapeutic development, but also discover new chemical probes for use in understanding Hsp70 biology.

Serological identification of HSP105 as a novel non-Hodgkin lymphoma therapeutic target

We reported that the clinical efficacy of dendritic cell–based vaccination is strongly associated with immunologic responses in relapsed B-cell non-Hodgkin lymphoma (B-NHL) patients. We have now investigated whether postvaccination antibodies from responders recognize novel shared NHL-restricted antigens. Immunohistochemistry and flow cytometry showed that they cross-react with allogeneic B-NHLs at significantly higher levels than their matched prevaccination samples or nonresponders' antibodies. Western blot analysis of DOHH-2 lymphoma proteome revealed a sharp band migrating at approximately 100 to 110 kDa only with postvaccine repertoires from responders. Mass spectrometry identified heat shock protein-105 (HSP105) in that molecular weight interval. Flow cytometry and immunohistochemistry disclosed HSP105 on the cell membrane and in the cytoplasm of B-NHL cell lines and 97 diagnostic specimens. A direct correlation between HSP105 expression and lymphoma aggressiveness was also apparent. Treatment of aggressive human B-NHL cell lines with an anti-HSP105 antibody had no direct effects on cell cycle or apoptosis but significantly reduced the tumor burden in xenotransplanted immunodeficient mice. In vivo antilymphoma activity of HSP105 engagement was associated with a significant local increase of Granzyme B+ killer cells that very likely contributed to the tumor-restricted necrosis. Our study adds HSP105 to the list of nononcogenes that can be exploited as antilymphoma targets.

Expression of a mutant HSP110 sensitizes colorectal cancer cells to chemotherapy and improves disease prognosis

Heat shock proteins (HSPs) are necessary for cancer cell survival. We identified a mutant of HSP110 (HSP110ΔE9) in colorectal cancer showing microsatellite instability (MSI CRC), generated from an aberrantly spliced mRNA and lacking the HSP110 substrate-binding domain. This mutant was expressed at variable levels in almost all MSI CRC cell lines and primary tumors tested. HSP110ΔE9 impaired both the normal cellular localization of HSP110 and its interaction with other HSPs, thus abrogating the chaperone activity and antiapoptotic function of HSP110 in a dominant-negative manner. HSP110ΔE9 overexpression caused the sensitization of cells to anticancer agents such as oxaliplatin and 5-fluorouracil, which are routinely prescribed in the adjuvant treatment of people with CRC. The survival and response to chemotherapy of subjects with MSI CRCs was associated with the tumor expression level of HSP110ΔE9. HSP110 may thus constitute a major determinant for both prognosis and treatment response in CRC.

Inhibition of ICAM2 induces radiosensitization in oral squamous cell carcinoma cells

We recently identified genes and molecular pathways related to radioresistance of oral squamous cell carcinoma (OSCC) using Affymetrix GeneChip. The current study focused on the association between one of the target genes, intercellular adhesion molecule 2 (ICAM2), and resistance to X-ray irradiation in OSCC cells, and evaluated the antitumor efficacy of combining ICAM2 small interfering RNA (siRNA) and X-ray irradiation. Downregulation of ICAM2 expression by siRNA enhanced radiosensitivity of OSCC cells with the increased apoptotic phenotype via phosphorylation (ser473) of AKT and activation of caspase-3. Moreover, overexpression of ICAM2 induced greater OSCC cell resistance to the X-ray irradiation with the radioresistance phenotype. These results suggested that ICAM2 silencing is closely related to sensitivity of OSCC cells to radiotherapy, and that ICAM2 may be an effective radiotherapeutic target for this disease.

Changes in the proteome of Huh7 cells induced by transient expression of hepatitis D virus RNA and antigens

Hepatitis delta virus (HDV) infection of human hepatocytes infected with the hepatitis B virus (HBV) is associated with increased liver damage and risk of fulminant disease. Although considerable progress has been made towards the elucidation of the mechanisms of HDV replication and pathogenesis, little is still known about the host factors involved in the different steps of the replication cycle. Here, we made use of a proteomic approach to analyse the global alterations in protein expression that arise in human hepatocytes separately transfected with each of the HDV components. Huh7 cells were transiently transfected with plasmids that code for the small delta antigen (S-HDAg), large delta antigen (L-HDAg), genomic RNA (gRNA), and antigenomic RNA (agRNA), respectively. Total protein extracts were separated by 2-DE and differentially expressed spots were identified by MALDI-TOF followed by database searching. We identified 32 proteins known to be involved in different pathways namely nucleic acid metabolism, protein metabolism, transport, signal transduction, apoptosis, and cell growth. Moreover, the down regulation of hnRNP D, HSP105, and triosephosphate isomerase was further confirmed by Real time PCR.

Regression of intestinal adenomas by vaccination with heat shock protein 105-pulsed bone marrow-derived dendritic cells in Apc(Min/+) mice

Heat shock protein (HSP) 105 is overexpressed in various cancers, but is expressed at low levels in many normal tissues, except for the testis. A vaccination with HSP105-pulsed bone marrow-derived dendritic cells (BM-DC) induced antitumor immunity without causing an autoimmune reaction in a mouse model. Because Apc(Min/+) mice develop multiple adenomas throughout the intestinal tract by 4 months of age, the mice provide a clinically relevant model of human intestinal tumor. In the present study, we investigated the efficacy of the HSP105-pulsed BM-DC vaccine on tumor regression in the Apc(Min/+) mouse. Western blot and immunohistochemical analyses revealed that the tumors of the Apc(Min/+) mice endogenously overexpressed HSP105. Immunization of the Apc(Min/+) mice with a HSP105-pulsed BM-DC vaccine at 6, 8, and 10 weeks of age significantly reduced the number of small-intestinal polyps accompanied by infiltration of both CD4(+) and CD8(+) T cells in the tumors. Cell depletion experiments proved that both CD4(+) and CD8(+) T cells play a critical role in the activation of antitumor immunity induced by these vaccinations. These findings indicate that the HSP105-pulsed BM-DC vaccine can provide potent immunotherapy for tumors that appear spontaneously as a result of the inactivation of a tumor suppressor gene, such as in the Apc(Min/+) mouse model.

Comparative analysis of microarray data identifies common responses to caloric restriction among mouse tissues

Caloric restriction has been extensively investigated as an intervention that both extends lifespan and delays age-related disease in mammals. In mice, much interest has centered on evaluating gene expression changes induced by caloric restriction (CR) in particular tissue types, but the overall systemic effect of CR among multiple tissues has been examined less extensively. This study presents a comparative analysis of microarray datasets that have collectively examined the effects of CR in 10 different tissue types (liver, heart, muscle, hypothalamus, hippocampus, white adipose tissue, colon, kidney, lung and cochlea). Using novel methods for comparative analysis of microarray data, detailed comparisons of the effects of CR among tissues are provided, and 28 genes for which expression response to CR is most shared among tissues are identified. These genes characterize common responses to CR, which consist of both activation and inhibition of stress-response pathways. With respect to liver tissue, transcriptional effects of CR exhibited surprisingly little overlap with those of aging, and a variable degree of overlap with the potential CR-mimetic drug resveratrol. These analyses shed light on the systemic transcriptional activity associated with CR diets, and also illustrate new approaches for comparative analysis of microarray datasets in the context of aging biology.

Identification of an overexpressed gene, HSPA4L, the product of which can provoke prevalent humoral immune responses in leukemia patients

OBJECTIVE

To identify leukemia-associated antigens, we applied the serological identification of antigens by the recombinant expression cloning (SEREX) method to a chronic myelogenous leukemia (CML) patient who achieved a cytogenetic response to interferon-alpha.

MATERIALS AND METHODS

Immunoscreening of the cDNA library was performed with sera from a CML patient. Two isolated antigens were used to evaluate the expression pattern using Northern blot analysis and quantitative reverse transcriptase polymerase chain reaction. Western blotting and enzyme-linked immunosorbent assay were also performed for serological analysis.

RESULTS

We identified 14 positive clones, representing five different antigens. Of these, two genes were further validated. One (clone 70) was the human polyribonucleotide nucleotidyltransferase 1 (PNPT1), which is the type I interferon (alpha/beta-responsive gene). The mRNA of clone 70 was ubiquitously expressed in normal human tissues. The other gene (clone 57) was the heat shock 70-kDa protein 4-like (HSPA4L), which is a member of the heat shock protein 110 family, whose mRNA is strongly expressed in normal human testis and overexpressed in leukemia cells. Seroactivity against HSPA4L was detected in 6 of 9 acute myeloid leukemia patients, 4 of 10 acute lymphoblastic leukemia patients, 9 of 11 CML patients, and none of 10 healthy volunteers. Leukemia patients had higher titer of the antibodies against the protein than healthy volunteers.

CONCLUSIONS

These results suggest that HSPA4L, a member of heat shock protein, is highly expressed by leukemia cells, and elicit humoral immune responses in leukemia patients, and it might be a potential target for antileukemia therapy and an antigen-specific immunotherapy for leukemia.