The chaperone system in glioblastoma multiforme and derived cell lines: diagnostic and mechanistic implications.

BACKGROUND: Glioblastoma multiforme (GBM) is the most common and malignant primary brain tumor in adults. Novel treatments are needed to counteract the molecular mechanisms of GBM growth and drug resistance. The chaperone system (CS) members are typically cytoprotective but some, termed Hsp, can become pathogenic and participate in carcinogenesis, along with the vascular endothelial growth factor (VEGF), and we investigated them in GBM biopsies and derived cell lines. The objectives were to identify diagnostic-prognostic biomarkers and gather information for developing chaperonotherapy. METHODS: Cell lines from GBMs were established, characterized (morphology, growth characteristics, and specific markers), and stored. Chaperones and angiogenic factors [Hsp10, Hsp27, Hsp60, Hsp70, Hsp90, FLT-1 (VEGFR-1), FLK1 (KDR, VEGFR-2), and FLT-4 (VEGFR-3)] were observed in cells by immunofluorescence while the chaperones were measured in tumor tissue by immunohistochemistry. RESULTS: Four cell lines were derived from four different GBMs; the cells were spindle shaped or polygonal and grew at high rates as adherent monolayers or clusters without evidence of contact inhibition. The astrocyte-specific glial fibrillary acidic protein (GFAP); and the neuronal NSE, malignancy VIM, and proliferation PCNA, markers were determined. The cells expressed GFAP but no NSE, indicating that they were primary glioblastoma cell lines, with high levels of Hsp10, Hsp27, Hsp60, Hsp90, and Flk1; and low levels of Hsp70, Flt1, and Flt4. CONCLUSIONS: Four cell lines were established derived from four out of ten GBM tumors studied. The cell lines showed intense positivity for chaperones studied and factors connected to malignancy and the tumors showed increased levels of chaperones, making them potential diagnostic-prognostic biomarkers and targets for anti-cancer compounds.

Lipid chaperones and associated diseases: a group of chaperonopathies defining a new nosological entity with implications for medical research and practice.

Fatty acid-binding proteins (FABPs) are lipid chaperones assisting in the trafficking of long-chain fatty acids with functions in various cell compartments, including oxidation, signaling, gene-transcription regulation, and storage. The various known FABP isoforms display distinctive tissue distribution, but some are active in more than one tissue. Quantitative and/or qualitative changes of FABPs are associated with pathological conditions. Increased circulating levels of FABPs are biomarkers of disorders such as obesity, insulin resistance, cardiovascular disease, and cancer. Deregulated expression and malfunction of FABPs can result from genetic alterations or posttranslational modifications and can be pathogenic. We have assembled the disorders with abnormal FABPs as chaperonopathies in a distinct nosological entity. This entity is similar but separate from that encompassing the chaperonopathies pertaining to protein chaperones. In this review, we discuss the role of FABPs in the pathogenesis of metabolic syndrome, cancer, and neurological diseases. We highlight the opportunities for improving diagnosis and treatment that open by encompassing all these pathological conditions within of a coherent nosological group, focusing on abnormal lipid chaperones as biomarkers of disease and etiological-pathogenic factors.

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.

Chaperonology: The Third Eye on Brain Gliomas.

The European Organization for Research and Treatment of Cancer/National Cancer Institute of Canada Phase III trial has validated as a current regimen for high-grade gliomas (HGG) a maximal safe surgical resection followed by radiotherapy with concurrent temozolamide. However, it is essential to balance maximal tumor resection with preservation of the patient’s neurological functions. Important developments in the fields of pre-operative and intra-operative neuro-imaging and neuro-monitoring have ameliorated the survival rate and the quality of life for patients affected by HGG. Moreover, even though the natural history remains extremely poor, advancement in the molecular and genetic fields have opened up new potential frontiers in the management of this devastating brain disease. In this review, we aim to present a comprehensive account of the main current pre-operative, intra-operative and molecular approaches to HGG with particular attention to specific chaperones, also called heat shock proteins (Hsps), which represent potential novel biomarkers to detect and follow up HGG, and could also be therapeutic agents.

Alzheimer's Disease and Molecular Chaperones: Current Knowledge and the Future of Chaperonotherapy.

BACKGROUND: Alzheimer's disease (AD) is a dementia, a neurodegenerative condition, and a protein-misfolding disease or proteinopathy, characterized by protein deposits, extracellular plaques and intracellular neurofibrillary tangles, which contain the AD's typical pathological proteins, abnormal ß-amyloid and hyperphosphorylated tau, respectively, and are located predominantly in the cortex of the frontal, parietal, and temporal brain lobes. What is the role of molecular chaperones in AD? Data indicate that molecular chaperones, also known as Hsp, are involved in AD, probably displaying protective roles and/or acting as pathogenic factors as it occurs in chaperonopathies in which case AD would be suitable to chaperonotherapy. Hsp60, Hsp70, and Hsp90 can be augmented and overexpressed or diminished and downregulated in various situations in AD affected tissues and cells, indicating they are active during disease development and progression. QUESTION: What is the role of molecular chaperones in AD? Data indicate that molecular chaperones, also known as Hsp, are involved in AD, probably displaying protective roles and/or acting as pathogenic factors as it occurs in chaperonopathies in which case AD would be suitable to chaperonotherapy. OBJECTIVE: Investigate the role of Hsp in AD, focusing on Hsp60, Hsp70, and Hsp90. METHOD: Critical examination of published data. RESULTS: Hsp60, Hsp70, and Hsp90 can be augmented and overexpressed or diminished and downregulated in various situations in AD affected tissues and cells, indicating they are active during disease development and progression. CONCLUSION AND PERSPECTIVES: Notwithstanding that the roles and mechanisms of action of chaperones in AD are still incompletely understood, there is already enough evidence to encourage the development of therapeutic strategies targeting them, either to block their activity in case they promote disease progression or to boost their performance when they are protective. The latter is an example of positive chaperonotherapy, which also includes chaperone replacement via gene or protein administration. On the contrary, if a chaperone is found to help the disease, it has to be blocked or eliminated, which constitute modalities of negative chaperonotherapy.

Hsp60 response in experimental and human temporal lobe epilepsy.

The mitochondrial chaperonin Hsp60 is a ubiquitous molecule with multiple roles, constitutively expressed and inducible by oxidative stress. In the brain, Hsp60 is widely distributed and has been implicated in neurological disorders, including epilepsy. A role for mitochondria and oxidative stress has been proposed in epileptogenesis of temporal lobe epilepsy (TLE). Here, we investigated the involvement of Hsp60 in TLE using animal and human samples. Hsp60 immunoreactivity in the hippocampus, measured by Western blotting and immunohistochemistry, was increased in a rat model of TLE. Hsp60 was also increased in the hippocampal dentate gyrus neurons somata and neuropil and hippocampus proper (CA3, CA1) of the epileptic rats. We also determined the circulating levels of Hsp60 in epileptic animals and TLE patients using ELISA. The epileptic rats showed circulating levels of Hsp60 higher than controls. Likewise, plasma post-seizure Hsp60 levels in patients were higher than before the seizure and those of controls. These results demonstrate that Hsp60 is increased in both animals and patients with TLE in affected tissues, and in plasma in response to epileptic seizures, and point to it as biomarker of hippocampal stress potentially useful for diagnosis and patient management.

Hsp10 nuclear localization and changes in lung cells response to cigarette smoke suggest novel roles for this chaperonin.

Heat-shock protein (Hsp)10 is the co-chaperone for Hsp60 inside mitochondria, but it also resides outside the organelle. Variations in its levels and intracellular distribution have been documented in pathological conditions, e.g. cancer and chronic obstructive pulmonary disease (COPD). Here, we show that Hsp10 in COPD undergoes changes at the molecular and subcellular levels in bronchial cells from human specimens and derived cell lines, intact or subjected to stress induced by cigarette smoke extract (CSE). Noteworthy findings are: (i) Hsp10 occurred in nuclei of epithelial and lamina propria cells of bronchial mucosa from non-smokers and smokers; (ii) human bronchial epithelial (16HBE) and lung fibroblast (HFL-1) cells, in vitro, showed Hsp10 in the nucleus, before and after CSE exposure; (iii) CSE stimulation did not increase the levels of Hsp10 but did elicit qualitative changes as indicated by molecular weight and isoelectric point shifts; and (iv) Hsp10 nuclear levels increased after CSE stimulation in HFL-1, indicating cytosol to nucleus migration, and although Hsp10 did not bind DNA, it bound a DNA-associated protein.

A human CCT5 gene mutation causing distal neuropathy impairs hexadecamer assembly in an archaeal model.

Chaperonins mediate protein folding in a cavity formed by multisubunit rings. The human CCT has eight non-identical subunits and the His147Arg mutation in one subunit, CCT5, causes neuropathy. Knowledge is scarce on the impact of this and other mutations upon the chaperone's structure and functions. To make progress, experimental models must be developed. We used an archaeal mutant homolog and demonstrated that the His147Arg mutant has impaired oligomeric assembly, ATPase activity, and defective protein homeostasis functions. These results establish for the first time that a human chaperonin gene defect can be reproduced and studied at the molecular level with an archaeal homolog. The major advantage of the system, consisting of rings with eight identical subunits, is that it amplifies the effects of a mutation as compared with the human counterpart, in which just one subunit per ring is defective. Therefore, the slight deficit of a non-lethal mutation can be detected and characterized.

The future of molecular chaperones and beyond.

Protection of hair cells by HSP70 released by supporting cells is reported by May et al. in this issue of the JCI. Their findings suggest a new way to reduce ototoxicity from therapeutic medications and raise larger questions about the role and integration of heat shock proteins in non­cell-autonomous responses to stress. Increasing evidence suggests an important role for extracellular heat shock proteins in both the nervous system and the immune system. The work also suggests that defective chaperones could cause ear disease and supports the potential use of chaperone therapeutics.

Chaperonopathies and chaperonotherapy. Hsp60 as therapeutic target in cancer: potential benefits and risks.

In this minireview we focus on Hsp60 as a target for anticancer therapy. We discuss the new concepts of chaperonopathies and chaperonotherapy and present information on Hsp60 localization in the cell membrane of human tumor cells. We describe novel mechanisms for Hsp60 reaching the extracellular environment that involve membrane-associated stages, as well as data on anti-Hsp60 antibodies found in human sera, both in normal subjects and patients affected by autoimmune diseases. Finally, we discuss possible therapeutic applications of anti-Hsp60 antibodies in cancer treatment, evaluating also side effects on non-tumor cells. In conclusion, the way for investigating Hsp60-targeted anti-tumor therapy is open, at least for those tumors that express Hsp60 on its surface and/or secrete it outside the cell, as is the search for the molecular mechanisms involved in Hsp60 translocation from cytosol to cell membrane: elucidation of this mechanism will greatly facilitate the optimization of chaperonotherapy centered on Hsp60 with anti-tumor efficacy and minimal side effects.

Hsp60, a novel target for antitumor therapy: structure-function features and prospective drugs design.

Heat shock protein 60 kDa (Hsp60) is a chaperone classically believed to be involved in assisting the correct folding of other mitochondrial proteins. Hsp60 also plays a role in cytoprotection against cell stressors, displaying for example, antiapoptotic potential. Despite the plethora of studies devoted to the mechanism of Hsp60's function, especially in prokaryotes, fundamental issues still remain unexplored, including the definition of its role in cancer. Key questions still unanswered pertain to the differences in structure-function features that might exist between the well-studied prokaryotic GroEL and the largely unexplored eukaryotic Hsp60 proteins. In this article we discuss these differences in sequence, structure, and roles of Hsp60, focusing on the human ortholog with the view of devising compounds to block its ability to favour tumor-cell growth and survival. Compounds currently known to directly or indirectly affect Hsp60 functions, such as protein folding, HIF-1α accumulation, or Hsp60-induced cell proliferation, are discussed along with strategies that might prove effective for developing Hsp60-targeting drugs for anticancer therapy.

HSP-molecular chaperones in cancer biogenesis and tumor therapy: an overview.

Molecular chaperones, many of which are heat-shock proteins (HSPs), are an important class of molecules with various functions. Pathological conditions in which chaperones become etiological and/or pathogenic factors are called chaperonopathies, and are classified into by defect, by excess, and by 'mistake'. In the latter case, the chaperone is structurally and functionally normal but participates in pathways that favor disease, although in some cases the chaperone may have post-translational modifications that may lead it to change its location and function and, thus, to become pathogenic. For example, HSP-chaperones are involved in carcinogenesis in various ways, so that some forms of cancer may be considered 'chaperonopathies by mistake'. This concept suggests new strategies for anticancer therapy (chaperonotherapy), in which the primary targets or therapeutic agents are chaperones. Chaperonotherapy consists of the utilization of HSP-chaperones for treating chaperonopathies, including cancer. Negative chaperonotherapy is aimed at eliminating or blocking the action of chaperones that favor carcinogenesis or other diseases, whereas positive chaperonotherapy uses chaperones, genes or proteins, to fight against diseases, such as cancer, by stimulating the immune system or the cellular defenses against stress.

The odyssey of Hsp60 from tumor cells to other destinations includes plasma membrane-associated stages and Golgi and exosomal protein-trafficking modalities.

BACKGROUND: In a previous work we showed for the first time that human tumor cells secrete Hsp60 via exosomes, which are considered immunologically active microvesicles involved in tumor progression. This finding raised questions concerning the route followed by Hsp60 to reach the exosomes, its location in them, and whether Hsp60 can be secreted also via other mechanisms, e.g., by the Golgi. We addressed these issues in the work presented here. PRINCIPAL FINDINGS: We found that Hsp60 localizes in the tumor cell plasma membrane, is associated with lipid rafts, and ends up in the exosomal membrane. We also found evidence that Hsp60 localizes in the Golgi apparatus and its secretion is prevented by an inhibitor of this organelle. CONCLUSIONS/SIGNIFICANCE: We propose a multistage process for the translocation of Hsp60 from the inside to the outside of the cell that includes a combination of protein traffic pathways and, ultimately, presence of the chaperonin in the circulating blood. The new information presented should help in designing future strategies for research and for developing diagnostic-monitoring means useful in clinical oncology.

The molecular anatomy of human Hsp60 and its similarity with that of bacterial orthologs and acetylcholine receptor reveal a potential pathogenetic role of anti-chaperonin immunity in myasthenia gravis.

Heat-shock protein 60 (Hsp60) is ubiquitous and highly conserved being present in eukaryotes and prokaryotes, including pathogens. This chaperonin, although typically a mitochondrial protein, can also be found in other intracellular sites, extracellularly, and in circulation. Thus, it can signal the immune system and participate in the development of inflammation and immune reactions. Both phenomena can be elicited by human and foreign Hsp60 (e.g., bacterial GroEL), when released into the blood by infectious agents. Consequently, all these Hsp60 proteins become part of a complex autoimmune response characterized by multiple cross reactions because of their structural similarities. In this study, we demonstrate that Hsp60 proteins from humans and two common pathogens, Chlamydia trachomatis and Chlamydia pneumoniae, share various sequence segments of potentially highly immunogenic epitopes with acetylcholine receptor α1 subunit (AChRα1). The structural data indicate that AChRα1 antibodies, implicated in the pathogenesis of myasthenia gravis, could very well be elicited and/or maintained by self- and/or bacterial Hsp60.

Heat shock protein-60 and risk for cardiovascular disease.

Cardiovascular disease (CVD) is a leading cause of morbidity and mortality worldwide. There is growing evidence that molecular chaperones, many of which are heat shock proteins HSPs, are involved in CVD pathogenesis. In this review we focus on HSP60, the human mitochondrial chaperone that also displays extramitochondrial and extracellular functions. HSP60 is typically cytoprotective but a number of stress conditions determine its conversion to a potentially toxic molecule for cells and tissues. We present illustrative examples of specific subtypes of CVD where HSP60 is implicated in the initiation and/or progression of disease. The data not only indicate a pathogenic role for HSP60 but also its potential as a biomarker with applications for diagnosis, assessing prognosis and response to treatment, as well as for preventing and treating CVD.

Immunohistochemistry of human Hsp60 in health and disease: from autoimmunity to cancer.

Hsp60 (also called Cpn60) is a chaperonin with essential functions for cell physiology and survival. Additionally, its involvement in the pathogenesis of a number of diseases (e.g., some autoimmune disorders and cancer) is becoming evident with new research. For example, the distribution and levels of Hsp60 in cells and tissues have been found altered in many pathologic conditions, and the significance of these alterations is being investigated in a number of laboratories. The aim of this ongoing research is to determine the meaning of these Hsp60 alterations with regard to pathogenetic mechanisms, diagnosis, classification of lesions, and assessing of prognosis and response to treatment. Hsp60 occurs in the mitochondria, i.e., its typical residence according to classic knowledge, and also in other locales, such as the cytosol, the cell membrane, the intercellular space, and biological fluids (e.g., blood and cerebrospinal fluid). Detection and quantitative determinations in all these locations are becoming essential components of laboratory pathology in clinics and research. Consequently, immunohistochemistry targeting Hsp60 is also becoming essential for pathologists and researchers interested in disorders involving this chaperonin. In this chapter, we briefly summarize some recent discoveries on the participation of Hsp60 in the pathogenesis of human diseases and describe in detail how to perform immunohistochemical reactions for detecting the chaperonin, determining its location, and measuring its levels of expression.

Changes in immunohistochemical levels and subcellular localization after therapy and correlation and colocalization with CD68 suggest a pathogenetic role of Hsp60 in ulcerative colitis.

In an earlier work, the role of heat shock protein (Hsp60) in the pathogenesis of ulcerative colitis (UC) was suggested by its significant increase in the pathological mucosa parallel with an increase in inflammatory cells. More data in this direction are reported in this work. We analyzed by immunohistochemistry biopsies of colon tissue from 2 groups of patients with UC and treated with either 5-aminosalicylic acid (5-ASA) alone or in combination with a probiotic. We looked for inflammatory markers and Hsp60. Both the treatments were effective in reducing symptoms but the group treated with both 5-ASA and probiotics showed better clinical results. Amelioration of symptoms was associated with reduction of both inflammation and Hsp60, a reduction that was most marked in the group treated with 5-ASA and probiotics. The levels of Hsp60 positively correlated with those of CD68-positive cells, and double immunofluorescence showed a high index of colocalization of the chaperonin and CD68 in lamina propria. Immunoelectron microscopy showed that Hsp60-classically a mitochondrial protein-was abundantly also present in cytosol in biopsies taken at the time of diagnosis, but not after the treatment. Our data suggest that Hsp60 is an active player in pathogenesis of UC and it can be hypothesized that the chaperonin is responsible, at least in part, for initiation and maintenance of disease.