HSP70 natively and specifically associates with an N-terminal dermcidin-derived peptide that contains an HLA-A*03 antigenic epitope

Dermcidin Enhances the Migration, Invasion, and Metastasis of Hepatocellular Carcinoma Cells In Vitro and In Vivo

BACKGROUND AND AIMS

Hepatocellular carcinoma (HCC) is a common primary liver neoplasm with high mortality. Dermcidin (DCD), an antimicrobial peptide, has been reported to participate in oncogenesis. This study assessed the effects and underlying molecular events of DCD overexpression and knockdown on the regulation of HCC progression in vitro and in vivo.

METHODS

The serum DCD level was detected using enzyme-linked immunosorbent assay. DCD overexpression, knockdown, and Ras-related C3 botulinum toxin substrate 1 (Rac1) rescue were performed in SK-HEP-1 cells using plasmids. Immunofluorescence staining, quantitative PCR, and Western blotting were used to detect the expression of different genes and proteins. Differences in HCC cell migration and invasion were detected by Transwell migration and invasion assays. A nude mouse HCC cell orthotopic model was employed to verify the in vitro data.

RESULTS

The level of serum DCD was higher in patients with HCC and in SK-HEP-1 cells. DCD overexpression caused upregulation of DCD, fibronectin, Rac1, and cell division control protein 42 homologue (Cdc42) mRNA and proteins as well as actin-related protein 2/3 (Arp2/3) protein (but reduced Arp2/3 mRNA levels) and activated Rac1 and Cdc42. Phenotypically, DCD overexpression induced HCC cell migration and invasion in vitro, whereas knockout of DCD expression had the opposite effects. A Rac1 rescue experiment in DCD-knockdown HCC cells increased HCC cell migration and invasion and increased the levels of active Rac1/total Rac1, Wiskott-Aldrich syndrome family protein (WASP), Arp2/3, and fibronectin. DCD overexpression induced HCC cell metastasis to the abdomen and liver in vivo.

CONCLUSIONS

DCD promotes HCC cell migration, invasion, and metastasis through upregulation of noncatalytic region of tyrosine kinase adaptor protein 1 (Nck1), Rac1, Cdc42, WASP, and Arp2/3, which induce actin cytoskeletal remodeling and fibronectin-mediated cell adhesion in HCC cells.

Heat Shock Protein 70 as a Double Agent Acting Inside and Outside the Cell: Insights into Autoimmunity

Heat shock proteins (Hsp) are a diverse group of constitutive and/or stress-induced molecules that are categorized into several classes on the basis of their molecular weight. Mammalian Hsp have been mostly regarded as intracellular chaperones that mediate a range of essential cellular functions, including proper folding of newly synthesized polypeptides, refolding of denatured proteins, protein transport, and stabilization of native proteins' structures. The well-characterized and highly evolutionarily conserved, stress-inducible 70-kDa heat shock protein (Hsp70), is a key molecular chaperone that is overexpressed in the cell in response to stress of various origin. Hsp70 exhibits an immunosuppressive activity via, e.g., downregulation of the nuclear factor-kappa B (NF-κB) activation, and pharmacological induction of Hsp70 can ameliorate the autoimmune arthritis development in animal models. Moreover, Hsp70 might be passively or actively released from the necrotic or stressed cells, respectively. Highly immunogenic extracellular Hsp70 has been reported to impact both the innate and adaptive immune responses, and to be implicated in the autoimmune reaction. In addition, preclinical studies revealed that immunization with highly conserved Hsp70 peptides could be regarded as a potential treatment target for autoimmune arthritis, such as the rheumatoid arthritis, via induction of antigen-specific regulatory T helper cells (also called Treg). Here, a dual role of the intra- and extracellular Hsp70 is presented in the context of the autoimmune reaction.

Heptamer Peptide Disassembles Native Amyloid in Human Plasma Through Heat Shock Protein 70

Proteostasis, which includes the repair and disposal of misfolded proteins, depends, in part, on the activity of heat shock proteins (HSPs), a well-known class of chaperone molecules. When this process fails, abnormally folded proteins may accumulate in cells, tissues, and blood. These species are a hallmark of protein aggregation diseases, but also amass during aging, often in the absence of an identified clinical disorder. We report that a neuroprotective cyclic heptapeptide, CHEC-7, which has been applied systemically as a therapeutic in animal neurodegeneration models, disrupts such aggregates and inhibits amyloidogenesis when added in nanomolar concentrations to human plasma. This effect includes aggregates of amyloid beta (Aβ1-40, 1-42), prominent features of Alzheimer's disease pathology. The activity of endogenous HSP70, a recently discovered target of the peptide, is required as demonstrated by both antibody blocking and application of pifithrin-μ, an HSP70 inhibitor. CHEC-7 is the first high-affinity compound to stimulate HSP70's disaggregase activity and therefore enable this endogenous mechanism in a human systemic environment, increasing the likelihood of a convenient therapy for protein aggregate disease, including age-related failures of protein repair.

The role of Dermcidin isoform-2 in the occurrence and severity of Diabetes

Diabetes is now epidemic worldwide. Several hundred-million peoples are presently suffering from this disease with other secondary-disorders. Stress, hypertension, sedentary life-style, carbohydrate/lipid metabolic-disorders due to genetic or environmental factors attributes to type-1 and/or type-2 diabetes. Present investigation demonstrates that stress-induced protein dermcidin isoform-2 (DCN-2) which appears in the serum of diabetic-patients play a key-role in this disease pathogenesis/severity. DCN-2 suppresses insulin production-release from liver/pancreas. It also increases the insulin-resistance. Stress-induction at the onset/progression of this disease is noticed as the high-level of lipid peroxides/low-level of free-thiols in association with increase of inflammatory-markers c-reactive protein and TNF-α. DCN-2 induced decrease in the synthesis of glucose-activated nitric oxide synthase (GANOS) and lower production of NO in liver has been shown here where NO is demonstrated to lower the expression of glucose trabsporter-4 (GLUT-4) and its translocation on liver membrane surface. This finally impairs glucose transport to organs from the extracellular fluid. Low level of glucose uptake further decreases glucose-induced insulin synthesis. The central role of DCN-2 has been demonstrated in type-1/type-2 diabetic individuals, in rodent hepatocytes and pancreatic-cell, tissue-slices, in-vitro and in-vivo experimental model. It can be concluded that stress-induced decrease in insulin synthesis/function, glucose transport is an interactive consequence of oxidative threats and inflammatory events.

Anti-inflammatory peptide regulates the supply of heat shock protein 70 monomers: implications for aging and age-related disease

Reducing the levels of toxic protein aggregates has become a focus of therapy for disorders like Alzheimer's and Parkinson's diseases, as well as for the general deterioration of cells and tissues during aging. One approach has been an attempt to influence the production or activity of a class of reparative chaperones called heat shock proteins (HSPs), of which HSP70 is a promising candidate. Manipulation of HSP70 expression results in disposal of misfolded protein aggregates that accumulate in aging and disease models. Recently, HSP70 has been shown to bind specifically to an amino-terminal sequence of a human diffusible survival evasion peptide (DSEP), dermcidin. This sequence includes CHEC-9, an orally available anti-inflammatory and cell survival peptide. In the present study, we found that the CHEC-9 peptide also binds HSP70 in the cytosol of the cerebral cortex after oral delivery in normal rats. Western analysis of non-heat-denatured, unreduced samples suggested that peptide treatment increased the level of active HSP70 monomers from the pool of chaperone oligomers, a process that may be stimulated by potentiation of the chaperone's adenosine triphosphatase (ATPase). In these samples, a small but consistent gel shift was observed for glyceraldehyde 3-phosphate dehydrogenase (GAPDH), a multifunctional protein whose aggregation is influenced by HSP70. CHEC-9 treatment of an in vitro model of α-synuclein aggregation also results in HSP70-dependent dissolution of these aggregates. HSP70 oligomer-monomer equilibrium and its potential to control protein aggregate disease warrant increased experimental attention, especially if a peptide fragment of an endogenous human protein can influence the process.

Dermcidin: a skeletal muscle myokine modulating cardiomyocyte survival and infarct size after coronary artery ligation

AIMS

Coronary artery disease is the leading cause of death in western countries, and its association with lower extremity peripheral artery disease (LE-PAD) represents an independent predictor of worse outcome. However, the molecular mechanisms underlying these effects are currently unknown.

METHODS AND RESULTS

To investigate these processes, we used in vitro approaches and several mouse models: (i) unilateral limb ischaemia by left common femoral artery ligation [peripheral ischaemia (PI), n = 38]; (ii) myocardial infarction by permanent ligation of the left descending coronary artery (MI, n = 40); (iii) MI after 5 weeks of limb ischaemia (PI + MI, n = 44); (iv) sham operation (SHAM, n = 20). Compared with MI, PI + MI hearts were characterized by a significant increase in cardiomyocyte apoptosis, larger infarct areas, and decreased cardiac function. By using a proteomic approach, we identified a ≅ 8 kDa circulating peptide, Dermcidin (DCD), secreted by ischaemic skeletal muscles, enhancing cardiomyocytes apoptosis under hypoxic conditions and infarct size after permanent coronary artery ligation. siRNA interference experiments to reduce DCD circulating levels significantly reduced infarct size and ameliorated cardiac function after MI.

CONCLUSION

Our data demonstrate that chronic limb ischaemia activates detrimental pathways in the ischaemic heart through humoral mechanisms of remote organ crosstalk. Thus, DCD may represent a novel important myokine modulating cardiomyocyte survival and function.

Seriniquinone, a selective anticancer agent, induces cell death by autophagocytosis, targeting the cancer-protective protein dermcidin

Natural products continue to provide vital treatment options for cancer. Although their translation into chemotherapeutics is complex, collaborative programs continue to deliver productive pipelines for cancer chemotherapy. A new natural product, seriniquinone, isolated from a marine bacterium of the genus Serinicoccus, demonstrated potent activity over a select set of tumor cell lines with particular selectivity toward melanoma cell lines. Upon entering the cell, its journey began by localization into the endoplasmic reticulum. Within 3 h, cells treated with seriniquinone underwent cell death marked by activation of autophagocytosis and gradually terminated through a caspase-9 apoptotic pathway. Using an immunoaffinity approach followed by multipoint validation, we identified the target of seriniquinone as the small protein, dermcidin. Combined, these findings revealed a small molecule motif in parallel with its therapeutic target, whose potential in cancer therapy may be significant. This discovery defines a new pharmacophore that displayed selective activity toward a distinct set of cell lines, predominantly melanoma, within the NCI 60 panel. This selectivity, along with the ease in medicinal chemical modification, provides a key opportunity to design and evaluate new treatments for those cancers that rely on dermcidin activity. Further, the use of dermcidin as a patient preselection biomarker may accelerate the development of more effective personalized treatments.

Analysis of Y-P30/Dermcidin expression and properties of the Y-P30 peptide

BACKGROUND

The survival promoting peptide Y-P30 has a variety of neuritogenic and neuroprotective effects in vitro and in vivo. In previous work we reported the expression of Y-P30/dermcidin in maternal peripheral blood mononuclear cells (PBMCs) and the transport of the protein to the fetal brain. In this study we analyzed hormonal regulation of Y-P30 in human immune cells and expression of Y-P30 in the placenta. We further studied the stability and secretion of the Y-P30 peptide.

RESULTS

We found indications that Y-P30 might be produced in human placenta. The Y-P30 mRNA was rarely found in isolated human PBMCs and alpha-feto-protein, human chorionic gonadotropin as well as estradiol combined with progesterone could not induce Y-P30 expression. Y-P30 was found to be extraordinarily stable; therefore, contamination with the peptide and the Y-P30/Dermcidin precursor mRNA is a serious concern in experiments looking at the expression of Y-P30/Dermcidin. In cultured cell lines and primary neurons we found that Y-P30 could be released, but neuronal uptake of Y-P30 was not observed.

CONCLUSIONS

Our data suggest that a source of Y-P30 apart from eccrine glands might be the placenta. The peptide can be secreted together with the signaling peptide and it might reach the fetal brain where it can exert its neuritogenic functions by binding to neuronal membranes.

The 'peptidome' of tumour-derived chaperone-rich cell lysate anti-cancer vaccines reveals potential tumour antigens that stimulate tumour immunity

Tumour-derived chaperone-rich cell lysate (CRCL) when isolated from tumour tissue or when embedded with peptide antigens is a potent anti-cancer vaccine consisting of numerous chaperone/heat shock proteins, including the highly immunogenic Hsp70, Hsp90, glucose regulated protein 94, and calreticulin. We have previously documented that CRCL provides both a source of tumour antigens and danger signals triggering antigen presenting cell activation. In this report we describe the 'peptidome' of potential antigens extracted from CRCL prepared from a murine tumour. Using mass spectrometry techniques we identify almost 60 different proteins of origin for the CRCL peptides; we determine that the parental proteins come from essentially all parts of the cell, and are involved in a broad range of functions. Further in silico analysis demonstrates that the parental proteins are components of major signalling networks of vital importance for cancer cell survival, proliferation, and migration. In many instances the peptides identified possess amino acid sequences that would allow their putative binding and display by murine major histocompatibility complex class I and II molecules, and there are also predicted binding motifs for Hsp70-type chaperones. By mixing fractionated pools of peptides with antigen-free (normal liver) CRCL, we were able to reconstitute effective anti-tumour activity of the vaccine, showing that the peptides are indeed the major purveyors of CRCL vaccines' efficacy.

A novel method to assay molecular chaperone activity of HSP70: evaluation of drug resistance in cancer treatment

In this work, we have proposed a novel method to specifically assay the molecular chaperone activity of HSP70 based on the HSP70-substrate peptide interaction. By selectively labeling the substrate peptide of HSP70 via host-guest interaction with two different cucurbituril species, the HSP70-substrate peptide interaction can be transduced into detectable signal readout. By using the signal readout, assay of the molecular chaperone activity of HSP70 can be achieved. Moreover, by using our method, chaperone activity of HSP70 can serve as a reliable indicator of drug resistance in cancer treatment. The experimental results reveal that enhanced chaperone activity of HSP70 is observed in both drug-resistant cancer cell line and the serum of cancer victim subject to anti-cancer therapy. Therefore, the proposed method to assay the molecular chaperone activity of HSP70 can be a tool of efficiency in evaluating therapeutic response in HSP70-targeted cancer treatment.

The immunosuppressive activity of heat shock protein 70

Heat shock protein 70 (HSP70) has previously been described as a potent antitumour vaccine. The mechanism relied on the ability of tumour derived HSP70 to associate with antigenic peptides, which, when cross presented, elicited a T cell mediated antitumour response. Subsequently, HSP70 was incorrectly described as a potent adjuvant of innate immunity, and although mistakes in the experimental approaches were exposed and associated with endotoxin contamination in the recombinant HSP70 specimen, questions still remain regarding this matter. Here we review only publications that have cautiously addressed the endotoxin contamination problem in HSP70 in order to reveal the real immunological function of the protein. Accordingly, “endotoxin free” HSP70 stimulates macrophages and delivers antigenic peptides to APCs, which effectively prime T cells mediating an antitumour reaction. Conversely, HSP70 has potent anti-inflammatory functions as follows: regulating T cell responses, reducing stimulatory capacity of DCs, and inducing development of immunosuppressive regulatory T cells. These activities were further associated with the immune evasive mechanism of tumours and implicated in the modulation of immune reactivity in autoimmune diseases and transplant-related clinical conditions. Consequently, the role of HSP70 in immune regulation is newly emerging and contrary to what was previously anticipated.

The multiple facets of dermcidin in cell survival and host defense

Eccrine sweat glands, which are distributed over the whole bodies of primates and humans, have long been regarded mainly to have a function in thermoregulation. However, the discovery of dermcidin-derived antimicrobial peptides in eccrine sweat demonstrated that sweat actively participates in the constitutive innate immune defense of human skin against infection. In the meantime, a number of studies proved the importance of dermcidin in skin host defense. Several reports also state that peptides processed from the dermcidin precursor protein exhibit a range of other biological functions in neuronal and cancer cells. This review summarizes the evidence gathered until now concerning the expression of dermcidin and the functional relevance of dermcidin-derived peptides.

Phage display biopanning identifies the translation initiation and elongation factors (IF1α-3 and eIF-3) as components of Hsp70-peptide complexes in breast tumour cells

The heat shock protein, HSP70, is over-expressed in many tumours and acts at the crossroads of key intracellular processes in its role as a molecular chaperone. HSP70 associates with a vast array of peptides, some of which are antigenic and can mount adaptive immune responses against the tumour from which they are derived. The pool of peptides associated with HSP70 represents a unique barcode of protein metabolism in tumour cells. With a view to identifying unique protein targets that may be developed as tumour biomarkers, we used purified HSP70 and its associated peptide pool (HSP70-peptide complexes, HSP70-PCs) from different human breast tumour cell lines as targets for phage display biopanning. Our results show that HSP70-PCs from each cell line interact with unique sets of peptides within the phage display library. One of the peptides, termed IST, enriched in the biopanning process, was used in a 'pull-down' assay to identify the original protein from which the HSP70-associated peptides may have been derived. The eukaryotic translation initiation factor 3 (eIF-3), a member of the elongation factor EF1α family, and the HSP GRP78, were pulled down by the IST peptide. All of these proteins are known to be up-regulated in cancer cells. Immunohistochemical staining of tumour tissue microarrays showed that the peptide co-localised with HSP70 in breast tumour tissue. The data indicate that the reservoir of peptides associated with HSP70 can act as a unique indicator of cellular protein activity and a novel source of potential tumour biomarkers.

Inducible heat shock protein 70 reduces T cell responses and stimulatory capacity of monocyte-derived dendritic cells

Heat shock protein 70 (Hsp70) has gained a lot of attention in the past decade due to its potential immunoregulatory functions. Some of the described proinflammatory functions of Hsp70 became controversial as they were based on recombinant Hsp70 proteins specimens, which were later shown to be endotoxin-contaminated. In this study we used low endotoxin inducible Hsp70 (also known as Hsp72, HSPA1A), and we observed that after a 24-h incubation of monocyte-derived immature dendritic cells (mo-iDCs) with 20 μg/ml of low endotoxin Hsp70, their ability to stimulate allogenic T cells was reduced. Interestingly, low endotoxin Hsp70 also significantly reduced T cell responses when they were simulated with either IL-2 or phytohemagglutinin, therefore showing that Hsp70 could alter T cell responses independently from its effect on mo-iDCs. We also reported a greater response of Hsp70 treatment when activated versus nonactivated T cells were used. This effect of Hsp70 was similar for all tested populations of T cells that included CD3(+), CD4(+), or CD8(+). Taken together, our observations strongly suggest that Hsp70 might dampen, rather than provoke, T cell-mediated inflammatory reactions in many clinical conditions where up-regulation of Hsp70 is observed.