Targeting Heat Shock Protein 27 in Cancer: A Druggable Target for Cancer Treatment?

Ivermectin, a potential anticancer drug derived from an antiparasitic drug

Ivermectin is a macrolide antiparasitic drug with a 16-membered ring that is widely used for the treatment of many parasitic diseases such as river blindness, elephantiasis and scabies. Satoshi ōmura and William C. Campbell won the 2015 Nobel Prize in Physiology or Medicine for the discovery of the excellent efficacy of ivermectin against parasitic diseases. Recently, ivermectin has been reported to inhibit the proliferation of several tumor cells by regulating multiple signaling pathways. This suggests that ivermectin may be an anticancer drug with great potential. Here, we reviewed the related mechanisms by which ivermectin inhibited the development of different cancers and promoted programmed cell death and discussed the prospects for the clinical application of ivermectin as an anticancer drug for neoplasm therapy.

Paclitaxel increases sensitivity of SKOV3 cells to hyperthermia by inhibiting heat shock protein 27

Hyperthermic intraperitoneal chemotherapy (HIPEC) is a promising treatment strategy for patients with peritoneal metastasis of ovarian cancer. Heat shock proteins (HSPs) play an important role in cellular stress during HIPEC treatment. The aim of the present study was to investigate whether paclitaxel can exert antitumor effects by inhibiting heat shock protein 27 (HSP27) expression during HIPEC treatment. Cell viability was detected by CCK8 assay. We used Western blot analysis to detect HSP27 expression under hyperthermia conditions with or without paclitaxel in SKOV3 cells. To further examine the role of HSP27 in the apoptosis, Bcl-2, Bax and Caspase-3 protein expression were additionally determined after reducing HSP27 levels using an siRNA strategy, and apoptosis was detected using the Annexin V/PI assay. The upregulation of HSP27 expression was accompanied with a rise in temperature. In addition, HSP27 could promote Bcl-2 expression, inhibit Bax and Caspase-3 expression, reduce the Bax / Bcl-2 ratio markedly in SKOV3 cells. Furthermore, paclitaxel could upregulate the Bax / Bcl-2 ratio by inhibiting HSP27 expression, and in turn, promoting apoptosis due to hyperthermia. Paclitaxel could also promote apoptosis by inhibiting HSP27 in SKOV3 cells. Our results demonstrate a synergistic effect between paclitaxel and hyperthermia at the cellular level.

Apoptosis, autophagy and atherosclerosis: Relationships and the role of Hsp27

Atherosclerosis is a multifactorial chronic inflammatory disease of the arterial wall, and an important pathological basis of coronary heart disease. Endothelial cells, vascular smooth muscle cells, and macrophages play important roles in the development of atherosclerosis. Of note, apoptosis and autophagy, two types of programmed cell death, influence the development and progression of atherosclerosis via the modulation of such cells. The small heat shock protein Hsp27 is a multifunctional protein induced by various stress factors and has a protective effect on cells. A large number of studies have demonstrated that Hsp27 plays an important role in regulating apoptosis. Recently, some studies have suggested that Hsp27 also participates in the autophagic process. Moreover, Hsp27 is closely related to the occurrence and development of atherosclerosis. Here, we summarize the molecular mechanisms of apoptosis and autophagy and discuss their effects on endothelial cells, vascular smooth muscle cells, and macrophages in the context of atherosclerotic procession. We further explore the involvement of Hsp27 in apoptosis, autophagy, and atherosclerosis. We speculate that Hsp27 may exert its anti-atherosclerotic role via the regulation of apoptosis and autophagy; this may provide the basis for the development of new approaches for the prevention and treatment of atherosclerosis.

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.

Extracellular Chaperones as Novel Biomarkers of Overall Cancer Progression and Efficacy of Anticancer Therapy

Exosomal heat shock proteins (Hsps) are involved in intercellular communication both in physiological and pathological conditions. They play a role in key processes of carcinogenesis including immune system regulation, cell differentiation, vascular homeostasis and metastasis formation. Thus, exosomal Hsps are emerging biomarkers of malignancies and possible therapeutic targets. Adolescents and young adults (AYAs) are patients aged 15–39 years. This age group, placed between pediatric and adult oncology, pose a particular challenge for cancer management. New biomarkers of cancer growth and progression as well as prognostic factors are desperately needed in AYAs. In this review, we attempted to summarize the current knowledge on the role of exosomal Hsps in selected solid tumors characteristic for the AYA population and/or associated with poor prognosis in this age group. These included malignant melanoma, brain tumors, and breast, colorectal, thyroid, hepatocellular, lung and gynecological tract carcinomas. The studies on exosomal Hsps in these tumors are limited; however; some have provided promising results. Although further research is needed, there is potential for future clinical applications of exosomal Hsps in AYA cancers, both as novel biomarkers of disease presence, progression or relapse, or as therapeutic targets or tools for drug delivery.

Clinicopathological Significance of Heat Shock Protein (HSP) 27 Expression in Gastric Cancer: A Updated Meta-Analysis

Aim

HSP27 is a protein chaperone protecting cell from heat shock, and upregulated HSP27 expression has been found in many different cancers. We conduct this update meta-analysis to evaluate the relationship between HSP27 expression and clinicopathological features.

Methods

We searched PubMed, Chinese CNKI, and WanFang databases to identify studies that assessed the association between clinicopathological feature and HSP27 expression in gastric cancer patients.

Results

We found overexpression of HSP27 was associated with incidence of gastric cancer (OR = 6.31, 95% CI = 1.10–36.15, P < 0.0001). However, there was no significant difference between HSP27 expression and gastric cancer differentiation, gender difference, lymph node metastasis, and distant metastasis.

Conclusion

Our meta-analysis study indicates that overexpression of HSP27 is associated with incidence of gastric cancer statistically.

Targets for protection and mitigation of radiation injury

Protection of normal tissues against toxic effects of ionizing radiation is a critical issue in clinical and environmental radiobiology. Investigations in recent decades have suggested potential targets that are involved in the protection against radiation-induced damages to normal tissues and can be proposed for mitigation of radiation injury. Emerging evidences have been shown to be in contrast to an old dogma in radiation biology; a major amount of reactive oxygen species (ROS) production and cell toxicity occur during some hours to years after exposure to ionizing radiation. This can be attributed to upregulation of inflammatory and fibrosis mediators, epigenetic changes and disruption of the normal metabolism of oxygen. In the current review, we explain the cellular and molecular changes following exposure of normal tissues to ionizing radiation. Furthermore, we review potential targets that can be proposed for protection and mitigation of radiation toxicity.

The soluble glycoprotein NMB (GPNMB) produced by macrophages induces cancer stemness and metastasis via CD44 and IL-33

In cancer, myeloid cells have tumor-supporting roles. We reported that the protein GPNMB (glycoprotein nonmetastatic B) was profoundly upregulated in macrophages interacting with tumor cells. Here, using mouse tumor models, we show that macrophage-derived soluble GPNMB increases tumor growth and metastasis in Gpnmb-mutant mice (DBA/2J). GPNMB triggers in the cancer cells the formation of self-renewing spheroids, which are characterized by the expression of cancer stem cell markers, prolonged cell survival and increased tumor-forming ability. Through the CD44 receptor, GPNMB mechanistically activates tumor cells to express the cytokine IL-33 and its receptor IL-1R1L. We also determined that recombinant IL-33 binding to IL-1R1L is sufficient to induce tumor spheroid formation with features of cancer stem cells. Overall, our results reveal a new paracrine axis, GPNMB and IL-33, which is activated during the cross talk of macrophages with tumor cells and eventually promotes cancer cell survival, the expansion of cancer stem cells and the acquisition of a metastatic phenotype.

ZNF322A-mediated protein phosphorylation induces autophagosome formation through modulation of IRS1-AKT glucose uptake and HSP-elicited UPR in lung cancer

Background

ZNF322A is an oncogenic transcription factor that belongs to the Cys2His2-type zinc-finger protein family. Accumulating evidence suggests that ZNF322A may contribute to the tumorigenesis of lung cancer, however, the ZNF322A-mediated downstream signaling pathways remain unknown.

Methods

To uncover ZNF322A-mediated functional network, we applied phosphopeptide enrichment and isobaric labeling strategies with mass spectrometry-based proteomics using A549 lung cancer cells, and analyzed the differentially expressed proteins of phosphoproteomic and proteomic profiles to determine ZNF322A-modulated pathways.

Results

ZNF322A highlighted a previously unidentified insulin signaling, heat stress, and signal attenuation at the post-translational level. Consistently, protein-phosphoprotein-kinase interaction network analysis revealed phosphorylation of IRS1 and HSP27 were altered upon ZNF322A-silenced lung cancer cells. Thus, we further investigated the molecular regulation of ZNF322A, and found the inhibitory transcriptional regulation of ZNF322A on PIM3, which was able to phosphorylate IRS1 at serine¹¹⁰¹ in order to manipulate glucose uptake via the PI3K/AKT/mTOR signaling pathway. Moreover, ZNF322A also affects the unfolded protein response by phosphorylation of HSP27^S82 and eIF2a^S51, and triggers autophagosome formation in lung cancer cells.

Conclusions

These findings not only give new information about the molecular regulation of the cellular proteins through ZNF322A at the post-translational level, but also provides a resource for the study of lung cancer therapy.

Specific Roles of HSP27 S15 Phosphorylation Augmenting the Nuclear Function of HER2 to Promote Trastuzumab Resistance

Trastuzumab (TZMB) is widely used as first line therapy for breast cancer (BC) patients overexpressing human epidermal growth factor receptor 2 (HER2). Despite its clinical benefits, many patients suffer from primary or secondary resistance to this drug within one year. As diverse molecular mechanisms occur contemporaneously during the resistance development, we focused on elucidating the role of heat shock protein 27 (HSP27) in TZMB-resistance, as this protein simultaneously regulates the function of diverse client molecules that are involved in the resistance mechanism. By extensively utilizing TZMB-refractory breast cancer cell lines transduced with diverse phosphovariants of HSP27, our study newly revealed that specific phosphorylation of HSP27 at S15 promoted its S78 phosphorylation and served as key mediator to promote direct interactions that increase the stability of HER2 and protein kinase B (AKT). This phosphorylation promoted nuclear translocation of HER2, enhancing the distinct nuclear function of HER2 that promoted AKT activation and cyclin D1 expression. Co-administration of TZMB and a functional inhibitor of HSP27, J2, significantly reduced the S15/78 phosphorylation of HSP27, which downregulated HER2 and its downstream signals, sensitizing TZMB-refractory cell, and JIMT1-xenograft mouse models to TZMB. Collectively, p-HSP27^S15 could serve as a valuable predictive marker and also a therapeutic target for TZMB-resistance.

Epigallocatechin Gallate Enhances MAL-PDT Cytotoxic Effect on PDT-Resistant Skin Cancer Squamous Cells

Photodynamic therapy (PDT) has been used to treat certain types of non-melanoma skin cancer with promising results. However, some skin lesions have not fully responded to this treatment, suggesting a potential PDT-resistant phenotype. Therefore, novel therapeutic alternatives must be identified that improve PDT in resistant skin cancer. In this study, we analyzed the cell viability, intracellular protoporphyrin IX (PpIX) content and subcellular localization, proliferation profile, cell death, reactive oxygen species (ROS) detection and relative gene expression in PDT-resistant HSC-1 cells. PDT-resistant HSC-1 cells show a low quantity of protoporphyrin IX and low levels of ROS, and thus a low rate of death cell. Furthermore, the resistant phenotype showed a downregulation of HSPB1, SLC15A2, FECH, SOD2 and an upregulation of HMBS and BIRC5 genes. On the other hand, epigallocatechin gallate catechin enhanced the MAL-PDT effect, increasing levels of protoporphyrin IX and ROS, and killing 100% of resistant cells. The resistant MAL-PDT model of skin cancer squamous cells (HSC-1) is a reliable and useful tool to understand PDT cytotoxicity and cellular response. These resistant cells were successfully sensitized with epigallocatechin gallate catechin. The in vitro epigallocatechin gallate catechin effect as an enhancer of MAL-PDT in resistant cells is promising in the treatment of difficult skin cancer lesions.

Molecular Chaperones in Cancer Stem Cells: Determinants of Stemness and Potential Targets for Antitumor Therapy

Cancer stem cells (CSCs) are a great challenge in the fight against cancer because these self-renewing tumorigenic cell fractions are thought to be responsible for metastasis dissemination and cases of tumor recurrence. In comparison with non-stem cancer cells, CSCs are known to be more resistant to chemotherapy, radiotherapy, and immunotherapy. Elucidation of mechanisms and factors that promote the emergence and existence of CSCs and their high resistance to cytotoxic treatments would help to develop effective CSC-targeting therapeutics. The present review is dedicated to the implication of molecular chaperones (protein regulators of polypeptide chain folding) in both the formation/maintenance of the CSC phenotype and cytoprotective machinery allowing CSCs to survive after drug or radiation exposure and evade immune attack. The major cellular chaperones, namely heat shock proteins (HSP90, HSP70, HSP40, HSP27), glucose-regulated proteins (GRP94, GRP78, GRP75), tumor necrosis factor receptor-associated protein 1 (TRAP1), peptidyl-prolyl isomerases, protein disulfide isomerases, calreticulin, and also a transcription heat shock factor 1 (HSF1) initiating HSP gene expression are here considered as determinants of the cancer cell stemness and potential targets for a therapeutic attack on CSCs. Various approaches and agents are discussed that may be used for inhibiting the chaperone-dependent development/manifestations of cancer cell stemness.

A Novel Model of Cancer Drug Resistance: Oncosomal Release of Cytotoxic and Antibody-Based Drugs

Extracellular vesicles (EVs), such as exosomes or oncosomes, often carry oncogenic molecules derived from tumor cells. In addition, accumulating evidence indicates that tumor cells can eject anti-cancer drugs such as chemotherapeutics and targeted drugs within EVs, a novel mechanism of drug resistance. The EV-releasing drug resistance phenotype is often coupled with cellular dedifferentiation and transformation in cells undergoing epithelial-mesenchymal transition (EMT), and the adoption of a cancer stem cell phenotype. The release of EVs is also involved in immunosuppression. Herein, we address different aspects by which EVs modulate the tumor microenvironment to become resistant to anticancer and antibody-based drugs, as well as the concept of the resistance-associated secretory phenotype (RASP).

Heat Shock Proteins: Agents of Cancer Development and Therapeutic Targets in Anti-Cancer Therapy

Heat shock proteins (HSPs) constitute a large family of molecular chaperones classified by their molecular weights, and they include HSP27, HSP40, HSP60, HSP70, and HSP90. HSPs function in diverse physiological and protective processes to assist in maintaining cellular homeostasis. In particular, HSPs participate in protein folding and maturation processes under diverse stressors such as heat shock, hypoxia, and degradation. Notably, HSPs also play essential roles across cancers as they are implicated in a variety of cancer-related activities such as cell proliferation, metastasis, and anti-cancer drug resistance. In this review, we comprehensively discuss the functions of HSPs in association with cancer initiation, progression, and metastasis and anti-cancer therapy resistance. Moreover, the potential utilization of HSPs to enhance the effects of chemo-, radio-, and immunotherapy is explored. Taken together, HSPs have multiple clinical usages as biomarkers for cancer diagnosis and prognosis as well as the potential therapeutic targets for anti-cancer treatment.

Chaperoning STAT3/5 by Heat Shock Proteins: Interest of Their Targeting in Cancer Therapy

While cells from multicellular organisms are dependent upon exogenous signals for their survival, growth, and proliferation, commitment to a specific cell fate requires the correct folding and maturation of proteins, as well as the degradation of misfolded or aggregated proteins within the cell. This general control of protein quality involves the expression and the activity of molecular chaperones such as heat shock proteins (HSPs). HSPs, through their interaction with the STAT3/STAT5 transcription factor pathway, can be crucial both for the tumorigenic properties of cancer cells (cell proliferation, survival) and for the microenvironmental immune cell compartment (differentiation, activation, cytokine secretion) that contributes to immunosuppression, which, in turn, potentially promotes tumor progression. Understanding the contribution of chaperones such as HSP27, HSP70, HSP90, and HSP110 to the STAT3/5 signaling pathway has raised the possibility of targeting such HSPs to specifically restrain STAT3/5 oncogenic functions. In this review, we present how HSPs control STAT3 and STAT5 activation, and vice versa, how the STAT signaling pathways modulate HSP expression. We also discuss whether targeting HSPs is a valid therapeutic option and which HSP would be the best candidate for such a strategy.

Molecular mechanisms in chaperonopathies: clues to understanding the histopathological abnormalities and developing novel therapies

Molecular chaperones, many of which are heat shock proteins (Hsps), are components of the chaperoning system and when defective can cause disease, the chaperonopathies. Chaperone-gene variants cause genetic chaperonopathies, whereas in the acquired chaperonopathies the genes are normal, but their protein products are not, due to aberrant post-transcriptional mechanisms, e.g. post-translational modifications (PTMs). Since the chaperoning system is widespread in the body, chaperonopathies affect various tissues and organs, making these diseases of interest to a wide range of medical specialties. Genetic chaperonopathies are uncommon but the acquired ones are frequent, encompassing various types of cancer, and inflammatory and autoimmune disorders. The clinical picture of chaperonopathies is known. Much less is known on the impact that pathogenic mutations and PTMs have on the properties and functions of chaperone molecules. Elucidation of these molecular alterations is necessary for understanding the mechanisms underpinning the tissue and organ abnormalities occurring in patients. To illustrate this issue, we discuss structural-functional alterations caused by mutation in the chaperones CCT5 and HSPA9, and PTM effects on Hsp60. The data provide insights into what may happen when CCT5 and HSPA9 malfunction in patients, e.g. accumulation of cytotoxic protein aggregates with tissue destruction; or for Hsp60 with aberrant PTM, degradation and/or secretion of the chaperonin with mitochondrial damage. These and other possibilities are now open for investigation. © 2019 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

Heat Shock Proteins in Glioblastoma Biology: Where Do We Stand?

Heat shock proteins (HSPs) are evolutionary conserved proteins that work as molecular chaperones and perform broad and crucial roles in proteostasis, an important process to preserve the integrity of proteins in different cell types, in health and disease. Their function in cancer is an important aspect to be considered for a better understanding of disease development and progression. Glioblastoma (GBM) is the most frequent and lethal brain cancer, with no effective therapies. In recent years, HSPs have been considered as possible targets for GBM therapy due their importance in different mechanisms that govern GBM malignance. In this review, we address current evidence on the role of several HSPs in the biology of GBMs, and how these molecules have been considered in different treatments in the context of this disease, including their activities in glioblastoma stem-like cells (GSCs), a small subpopulation able to drive GBM growth. Additionally, we highlight recent works that approach other classes of chaperones, such as histone and mitochondrial chaperones, as important molecules for GBM aggressiveness. Herein, we provide new insights into how HSPs and their partners play pivotal roles in GBM biology and may open new therapeutic avenues for GBM based on proteostasis machinery.