Patterns of GRP78 and MTJ1 expression in primary cutaneous malignant melanoma

Comprehensive Analysis of the Role of Heat Shock Proteins in the Immune Microenvironment and Clinical Significance of Hepatocellular Carcinoma

Purpose

Hepatocellular carcinoma (HCC) is a prevalent malignancy that not only imposes a substantial financial burden but also significantly impacts the quality of life and overall survival of affected individuals. Heat shock proteins (HSPs) are a protein class with significant involvement in safeguarding and restoring cellular integrity. They help restore proper protein structure by binding to and refolding denatured proteins. However, the specific role of HSPs in HCC requires further investigation.

Methods

We analyzed the genomic characteristics of HSPs in liver cancer in the TCGA and ICGC databases, and functional enriched analysis of HSPs. Construction of an HSPs-Related Prognostic Model for patients with hepatocellular carcinoma. HSP-related risk score (HRRS) was identified as an independent prognostic factor in patients with hepatocellular carcinoma, and the clinical pathological characteristics and immune microenvironment of high-risk and low-risk groups were compared. Further, we studied HRRS-based liver cancer treatment strategies and confirmed the protein expression of HSPD1 and DNAJC5 in normal liver tissues and hepatocellular carcinoma tissues by collecting human hepatocellular carcinoma tissues.

Results

We observed elevated expression levels of most HSPs across HCC tissues. In addition, 14 hSPs were found to be related to prognostic significance among HCC patients and utilized to develop HRRS prognostic model for prognosis prediction and risk stratification. The prognostic and immunotherapeutic response predictive value of HRRS was validated utilizing data from TCGA and GEO cohorts. Moreover, we created a nomogram to assess HRRS clinical utility and verified its efficiency through various methods. Through IHC was found that HSPD1 and DNAJC5 were significantly overexpressed in hepatocellular carcinoma tissues.

Conclusion

Our results lead us to conclude that HCC's development and progression are intimately associated with HSPs, and the HRRS model represents a potentially robust prognostic model that could assist in clinical decision-making regarding chemotherapy and immunotherapy for HCC patients. Moreover, HSPD1 and DNAJC5 have the potential to serve as therapeutic targets for HCC.

DNAJC1 facilitates glioblastoma progression by promoting extracellular matrix reorganization and macrophage infiltration

BACKGROUND

Glioblastoma (GBM) is a high-grade and heterogeneous subtype of glioma that presents a substantial challenge to human health, characterized by a poor prognosis and low survival rates. Despite its known involvement in regulating leukemia and melanoma, the function and mechanism of DNAJC1 in GBM remain poorly understood.

METHODS

Utilizing data from the TCGA, CGGA, and GEO databases, we investigated the expression pattern of DNAJC1 and its correlation with clinical characteristics in GBM specimens. Loss-of-function experiments were conducted to explore the impact of DNAJC1 on GBM cell lines, with co-culture experiments assessing macrophage infiltration and functional marker expression.

RESULTS

Our analysis demonstrated frequent overexpression of DNAJC1 in GBM, significantly associated with various clinical characteristics including WHO grade, IDH status, chromosome 1p/19q codeletion, and histological type. Moreover, Kaplan‒Meier and ROC analyses revealed DNAJC1 as a negative prognostic predictor and a promising diagnostic biomarker for GBM patients. Functional studies indicated that silencing DNAJC1 impeded cell proliferation and migration, induced cell cycle arrest, and enhanced apoptosis. Mechanistically, DNAJC1 was implicated in stimulating extracellular matrix reorganization, triggering the epithelial-mesenchymal transition (EMT) process, and initiating immunosuppressive macrophage infiltration.

CONCLUSIONS

Our findings underscore the pivotal role of DNAJC1 in GBM pathogenesis, suggesting its potential as a diagnostic and therapeutic target for this challenging disease.

Unveiling the dark side of glucose-regulated protein 78 (GRP78) in cancers and other human pathology: a systematic review

Glucose-Regulated Protein 78 (GRP78) is a chaperone protein that is predominantly expressed in the lumen of the endoplasmic reticulum. GRP78 plays a crucial role in protein folding by assisting in the assembly of misfolded proteins. Under cellular stress conditions, GRP78 can translocate to the cell surface (csGRP78) were it interacts with different ligands to initiate various intracellular pathways. The expression of csGRP78 has been associated with tumor initiation and progression of multiple cancer types. This review provides a comprehensive analysis of the existing evidence on the roles of GRP78 in various types of cancer and other human pathology. Additionally, the review discusses the current understanding of the mechanisms underlying GRP78's involvement in tumorigenesis and cancer advancement. Furthermore, we highlight recent innovative approaches employed in downregulating GRP78 expression in cancers as a potential therapeutic target.

Is GRP78 (Glucose-regulated protein 78) a prognostic biomarker in differents types of cancer? A systematic review and meta-analysis

GRP78 is a chaperone with anti-apoptotic function associated with aggressive tumors. This systematic review aimed to evaluate GRP78 expression in cancer and its relation to prognosis outcomes. This review was conducted in different databases searching for human cancer studies assessing GRP78 immunohistochemical levels on tissue samples. A total of 98 manuscripts were included. In 62% of the studies, GRP78 was associated with a worse prognosis. A meta-analysis included 29 studies that detected a significantly higher expression of GRP78 in cancer tissues (RR= 2.35, 95% CI 1.75-3.15) compared to control. A meta-analysis of 3 and 5-years Overall Survival revealed an increased risk of death for tumors with high expression of GRP78 (RR=1.36, 95%CI 1.16-1,59, I² = 57%) and (RR=1.65, 95%CI 1.22-2.21, I² =64%), respectively. GRP78 is an important prognostic biomarker for different types of cancer and a promising therapeutic target.

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

Heat shock proteins (HSPs) constitute a large family of conserved proteins acting as molecular chaperones that play a key role in intracellular protein homeostasis, regulation of apoptosis, and protection from various stress factors (including hypoxia, thermal stress, oxidative stress). Apart from their intracellular localization, members of different HSP families such as small HSPs, HSP40, HSP60, HSP70 and HSP90 have been found to be localized on the plasma membrane of malignantly transformed cells. In the current article, the role of membrane-associated molecular chaperones in normal and tumor cells is comprehensively reviewed with implications of these proteins as plausible targets for cancer therapy and diagnostics.

Cytokine-induced translocation of GRP78 to the plasma membrane triggers a pro-apoptotic feedback loop in pancreatic beta cells

The 78-kDa glucose-regulated protein (GRP78) is an ubiquitously expressed endoplasmic reticulum chaperone, with a central role in maintaining protein homeostasis. Recently, an alternative role for GRP78 under stress conditions has been proposed, with stress-induced extracellular secretion and translocation of GRP78 to the cell surface where it acts as a multifunctional signaling receptor. Here we demonstrate translocation of GRP78 to the surface of human EndoC-βH1 cells and primary human islets upon cytokine exposure, in analogy to observations in rodent INS-1E and MIN6 beta cell lines. We show that GRP78 is shuttled via the anterograde secretory pathway, through the Golgi complex and secretory granules, and identify the DNAJ homolog subfamily C member 3 (DNAJC3) as a GRP78-interacting protein that facilitates its membrane translocation. Evaluation of downstream signaling pathways, using N- and C-terminal anti-GRP78 blocking antibodies, demonstrates that both GRP78 signaling domains initiate pro-apoptotic signaling cascades in beta cells. Extracellular GRP78 itself is identified as a ligand for cell surface GRP78 (sGRP78), increasing caspase 3/7 activity and cell death upon binding, which is accompanied by enhanced Chop and Bax mRNA expression. These results suggest that inflammatory cytokines induce a self-destructive pro-apoptotic feedback loop through the secretion and membrane translocation of GRP78. This proapoptotic function distinguishes the role of sGRP78 in beta cells from its reported anti-apoptotic and proliferative role in cancer cells, opening the road for the use of compounds that block sGRP78 as potential beta cell-preserving therapies in type 1 diabetes.

Tunicamycin-induced ER stress in breast cancer cells neither expresses GRP78 on the surface nor secretes it into the media

GRP78 (an Mr 78 kDa calcium dependent glucose binding protein) is located in ER lumen. It functions as ER chaperone and translocates proteins for glycosylation at the asparagine residue present in the sequon Asn-X-Ser/Thr. Paraffin sections from N-glycosylation inhibitor tunicamycin treated ER-/PR-/HER2+ (double negative) breast tumor in athymic nude mice exhibited reduced N-glycan but increased GRP78 expression. We have evaluated the effect of tunicamycin on cellular localization of GRP78 in metastatic human breast cancer cells MDA-MB-231 (ER-/PR-/HER2-). Tunicamycin inhibited cell proliferation in a time and dose-dependent manner. Nonmetastatic estrogen receptor positive (ER+) MCF-7 breast cancer cells were also equally effective. GRP78 expression (protein and mRNA) was higher in tunicamycin (1.0 μg/mL) treated MCF-7 and MDA-MB-231 cells. GRP78 is an ER stress marker, so we have followed its intracellular localization using immunofluorescence microscopy after subjecting the cancer cells to various stress conditions. Unfixed cells stained with either FITC-conjugated Concanavalin A (Con A) or Texas-red conjugated wheat germ agglutinin (WGA) exhibited surface expression of N-glycans but not GRP78. GRP78 became detectable only after a brief exposure of cells to ice-cold methanol. Western blotting did not detect GRP78 in conditioned media of cancer cells whereas it did for MMP-1. The conclusion, GRP78 is expressed neither on the outer-leaflet of the (ER-/PR-/HER2-) human breast cancer cells nor it is secreted into the culture media during tunicamycin-induced ER stress. Our study therefore suggests strongly that anti-tumorigenic action of tunicamycin can be modeled to develop next generation cancer therapy, i.e., glycotherapy for treating breast and other sold tumors.

Comparative gene expression analysis after exposure to 123I-iododeoxyuridine, γ- and α-radiation-potential biomarkers for the discrimination of radiation qualities

Gene expression analysis was carried out in Jurkat cells in order to identify candidate genes showing significant gene expression alterations allowing robust discrimination of the Auger emitter 123I, incorporated into the DNA as 123I-iododeoxyuridine (123IUdR), from α- and γ-radiation. The γ-H2AX foci assay was used to determine equi-effect doses or activity, and gene expression analysis was carried out at similar levels of foci induction. Comparative gene expression analysis was performed employing whole human genome DNA microarrays. Candidate genes had to show significant expression changes and no altered gene regulation or opposite regulation after exposure to the radiation quality to be compared. The gene expression of all candidate genes was validated by quantitative real-time PCR. The functional categorization of significantly deregulated genes revealed that chromatin organization and apoptosis were generally affected. After exposure to 123IUdR, α-particles and γ-rays, at equi-effect doses/activity, 155, 316 and 982 genes were exclusively regulated, respectively. Applying the stringent requirements for candidate genes, four (PPP1R14C, TNFAIP8L1, DNAJC1 and PRTFDC1), one (KLF10) and one (TNFAIP8L1) gene(s) were identified, respectively allowing reliable discrimination between γ- and 123IUdR exposure, γ- and α-radiation, and α- and 123IUdR exposure, respectively. The Auger emitter 123I induced specific gene expression patterns in Jurkat cells when compared with γ- and α-irradiation, suggesting a unique cellular response after 123IUdR exposure. Gene expression analysis might be an effective tool for identifying biomarkers for discriminating different radiation qualities and, furthermore, might help to explain the varying biological effectiveness at the mechanistic level.

Suppression of GRP78 sensitizes human colorectal cancer cells to oxaliplatin by downregulation of CD24

Glucose-regulated protein 78 (GRP78) is an endoplasmic reticulum stress signaling regulator with anti-apoptotic properties. It has been demonstrated to promote tumor proliferation, survival and metastasis, and to confer resistance against a large variety of therapies. CD24 is a glycosyl-phosphatidylinositol-anchored protein, which is known to have a role in tumor progression, particularly in colorectal cancer (CRC). In the present study, oxaliplatin (L-OHP) was demonstrated to decrease the expression of CD24 in HT29 cells. Knockdown of CD24 using small interfering RNA resulted in sensitization of HT29 cells to L-OHP. By contrast, overexpression of CD24 rendered SW480 cells resistant to L-OHP, which indicated that CD24 antagonized L-OHP-induced cytotoxicity. A co-immunoprecipitation assay revealed that GRP78 physically associates with CD24. L-OHP suppresses the expression of GRP78 and CD24, in part come from the inhibition of interaction between the two. Suppression of GRP78 caused downregulation of CD24 expression and enhanced L-OHP-induced CD24 inhibition. Furthermore, down-regulation of GPR78 with a pharmacological inhibitor sensitized the CRC cells to L-OHP. Collectively, the present results indicate that CD24 antagonizes L-OHP-induced cytotoxicity and that GRP78 is involved in this process. A novel mechanism via which CRC cells acquire resistance to L-OHP was thereby revealed. Use of a combination of compounds which suppress GRP78 may help to improve the effectiveness of L-OHP in the treatment of CRC.

Autoantibodies against the cell surface-associated chaperone GRP78 stimulate tumor growth via tissue factor

Tumor cells display on their surface several molecular chaperones that normally reside in the endoplasmic reticulum. Because this display is unique to cancer cells, these chaperones are attractive targets for drug development. Previous epitope-mapping of autoantibodies (AutoAbs) from prostate cancer patients identified the 78-kDa glucose-regulated protein (GRP78) as one such target. Although we previously showed that anti-GRP78 AutoAbs increase tissue factor (TF) procoagulant activity on the surface of tumor cells, the direct effect of TF activation on tumor growth was not examined. In this study, we explore the interplay between the AutoAbs against cell surface-associated GRP78, TF expression/activity, and prostate cancer progression. First, we show that tumor GRP78 expression correlates with disease stage and that anti-GRP78 AutoAb levels parallel prostate-specific antigen concentrations in patient-derived serum samples. Second, we demonstrate that these anti-GRP78 AutoAbs target cell-surface GRP78, activating the unfolded protein response and inducing tumor cell proliferation through a TF-dependent mechanism, a specific effect reversed by neutralization or immunodepletion of the AutoAb pool. Finally, these AutoAbs enhance tumor growth in mice bearing human prostate cancer xenografts, and heparin derivatives specifically abrogate this effect by blocking AutoAb binding to cell-surface GRP78 and decreasing TF expression/activity. Together, these results establish a molecular mechanism in which AutoAbs against cell-surface GRP78 drive TF-mediated tumor progression in an experimental model of prostate cancer. Heparin derivatives counteract this mechanism and, as such, represent potentially appealing compounds to be evaluated in well-designed translational clinical trials.

The unfolded protein response impacts melanoma progression by enhancing FGF expression and can be antagonized by a chemical chaperone

The mechanisms hallmarking melanoma progression are insufficiently understood. Here we studied the impact of the unfolded protein response (UPR) - a signalling cascade playing ambiguous roles in carcinogenesis - in melanoma malignancy. We identified isogenic patient-derived melanoma cell lines harboring BRAF^V600E-mutations as a model system to study the role of intrinsic UPR in melanoma progression. We show that the activity of the three effector pathways of the UPR (ATF6, PERK and IRE1) was increased in metastatic compared to non-metastatic cells. Increased UPR-activity was associated with increased flexibility to cope with ER stress. The activity of the ATF6- and the PERK-, but not the IRE-pathway, correlated with poor survival in melanoma patients. Using whole-genome expression analysis, we show that the UPR is an inducer of FGF1 and FGF2 expression and cell migration. Antagonization of the UPR using the chemical chaperone 4-phenylbutyric acid (4-PBA) reduced FGF expression and inhibited cell migration and viability. Consistently, FGF expression positively correlated with the activity of ATF6 and PERK in human melanomas. We conclude that chronic UPR stimulates the FGF/FGF-receptor signalling axis and promotes melanoma progression. Hence, the development of potent chemical chaperones to antagonize the UPR might be a therapeutic approach to target melanoma.

Antitumor agent 25-epi Ritterostatin GN1N induces endoplasmic reticulum stress and autophagy mediated cell death in melanoma cells

Metastatic melanoma is the most aggressive of all skin cancers and is associated with poor prognosis owing to lack of effective treatments. 25-epi Ritterostatin G_N1_N is a novel antitumor agent with yet undefined mechanisms of action. We sought to delineate the antitumor mechanisms of 25-epi Ritterostatin G_N1_N in melanoma cells to determine the potential of this compound as a treatment for melanoma. Activation of the endoplasmic reticulum (ER) stress protein glucose-regulated protein 78 (GRP78) has been associated with increased melanoma progression, oncogenic signaling, drug resistance, and suppression of cell death. We found that 25-epi Ritterostatin G_N1_N induced cell death in melanoma cells at nanomolar concentrations, and this cell death was characterized by inhibition of GRP78 expression, increased expression of the ER stress marker CHOP, loss of mitochondrial membrane potential, and lipidation of the autophagy marker protein LC3B. Importantly, normal melanocytes exhibited limited sensitivity to 25-epi Ritterostatin G_N1_N. Subsequent in vivo results demonstrated that 25-epi Ritterostatin G_N1_N reduced melanoma growth in mouse tumor xenografts and did not affect body weight, suggesting minimal toxicity. In summary, our findings indicate that 25-epi Ritterostatin G_N1_N causes ER stress and massive autophagy, leading to collapse of mitochondrial membrane potential and cell death in melanoma cells, with minimal effects in normal melanocytes. Thus, 25-epi Ritterostatin G_N1_N is a promising anticancer agent that warrants further investigation.

Integrins are not essential for entry of coxsackievirus A9 into SW480 human colon adenocarcinoma cells

Background

Coxsackievirus A9 (CV-A9) is a pathogenic enterovirus type within the family Picornaviridae. CV-A9 infects A549 human epithelial lung carcinoma cells by attaching to the αVβ6 integrin receptor through a highly conserved Arg-Gly-Asp (RGD) motif, which is located at the exposed carboxy-terminus of the capsid protein VP1 detected in all studied clinical isolates. However, genetically-modified CV-A9 that lacks the RGD motif (CV-A9-RGDdel) has been shown to be infectious in some cell lines but not in A549, suggesting that RGD-mediated integrin binding is not always essential for efficient entry of CV-A9.

Methods

Two cell lines, A549 and SW480, were used in the study. SW480 was the study object for the integrin-independent entry and A549 was used as the control for integrin-dependent entry. Receptor levels were quantitated by cell sorting and quantitative PCR. Antibody blocking assay and siRNA silencing of receptor-encoding genes were used to block virus infection. Peptide phage display library was used to identify peptide binders to CV-A9. Immunofluorescence and confocal microscopy were used to visualize the virus infection in the cells.

Results

We investigated the receptor use and early stages of CV-A9 internalization to SW480 human epithelial colon adenocarcinoma cells. Contrary to A549 infection, we showed that both CV-A9 and CV-A9-RGDdel internalized into SW480 cells and that function-blocking anti-αV integrin antibodies had no effect on the binding and entry of CV-A9. Whereas siRNA silencing of β6 integrin subunit had no influence on virus infection in SW480, silencing of β2-microglobulin (β2M) inhibited the virus infection in both cell lines. By using a peptide phage display screening, the virus-binding peptide identical to the N-terminal sequence of HSPA5 protein was identified and shown to block the virus infection in both A549 and SW480 cell lines. HSPA5 was also found to co-localize with CV-A9 at the SW480 cell periphery during the early stages of infection by confocal microscopy.

Conclusions

The data suggest that while αVβ6 integrin is essential for CV-A9 in A549 cell line, it is not required in SW480 cell line in which β2M and HSPA5 alone are sufficient for CV-A9 infection. This suggests that the choice of CV-A9 receptor(s) is dependent on the tissue/cellular environment.

Electronic supplementary material

The online version of this article (doi:10.1186/s12985-016-0619-y) contains supplementary material, which is available to authorized users.

Clinical and Pathological Significance of ER Stress Marker (BiP/GRP78 and PERK) Expression in Malignant Melanoma

Glucose-regulated protein of 78 kD (GRP78) also referred to as immunoglobulin heavy chain binding protein (BiP/GRP78) plays an important role in the endoplasmic reticulum (ER) stress. The level of BiP/GRP78 is highly elevated in various human cancers. The purpose of this study is to examine the prognostic significance of BiP/GRP78 expression in patients with malignant melanoma. A total of 133 malignant melanoma patients were analyzed, and tumor specimens were stained by immunohistochemistry for BiP/GRP78, PKR-like endoplasmic reticulum kinase (PERK), Ki-67, p53 and microvessel density (MVD) determined by CD34. BiP/GRP78 and PERK were highly expressed in 40 % (53/133) and 78 % (104/133), respectively. BiP/GRP78 disclosed a significant relationship with PERK expression, thickness, T factor, N factor, disease staging, cell proliferation (Ki-67) and MVD (CD34). By multivariate analysis, the high expression of BiP/GRP78 was identified as an independent prognostic factor for predicting poor survival against malignant melanoma. The increased BiP/GRP78 expression was clarified as an independent prognostic marker for predicting worse outcome. ER stress marker, BiP/GRP78 could be a powerful molecular target for the treatment of malignant melanoma.

Gr(i)p the ER to Stress Out Melanoma

Because of their elevated steady-state stress level, cancer cells are particularly sensitive to perturbation of mechanisms regulating protein homeostasis. In this issue, Cerezo and colleagues show that pharmacologic modulation of GRP78, master regulator of the unfolded protein response in the endoplasmic reticulum, can be exploited for cancer treatment.

Melanoma and the Unfolded Protein Response

The UPR (unfolded protein response) has been identified as a key factor in the progression and metastasis of cancers, notably melanoma. Several mediators of the UPR are upregulated in cancers, e.g., high levels of GRP78 (glucose-regulator protein 78 kDa) correlate with progression and poor outcome in melanoma patients. The proliferative burden of cancer induces stress and activates several cellular stress responses. The UPR is a tightly orchestrated stress response that is activated upon the accumulation of unfolded proteins within the ER (endoplasmic reticulum). The UPR is designed to mediate two conflicting outcomtes, recovery and apoptosis. As a result, the UPR initiates a widespread signaling cascade to return the cell to homeostasis and failing to achieve cellular recovery, initiates UPR-induced apoptosis. There is evidence that ER stress and subsequently the UPR promote tumourigenesis and metastasis. The complete role of the UPR has yet to be defined. Understanding how the UPR allows for adaption to stress and thereby assists in cancer progression is important in defining an archetype of melanoma pathology. In addition, elucidation of the mechanisms of the UPR may lead to development of effective treatments of metastatic melanoma.

Cell surface GRP78: A potential marker of good prognosis and response to chemotherapy in breast cancer

The 78-kDa glucose-regulated protein (GRP78) is a stress induced heat shock protein which, under limiting conditions, functions as a cell surface signaling receptor. Tumor cells are considered to be subjected to a physiologically stressful microenvironment due to their excessive growth. The role of GRP78 in tumor survival has been of notable interest. The present study aimed to assess the potential prognostic and predictive value of cell surface GRP78 expression in breast cancer tumor cells. Cell surface and cytoplasmic expression of GRP78 was examined by immunohistochemical staining of GRP78 in breast cancer archival paraffin-embedded tumor specimens. The cohort studied included breast cancer patients with operable T1,2, estrogen receptor-positive, node-negative cancer who were assessed using the Oncotype DX gene profile, as well as patients with locally advanced disease prior to and following neoadjuvant systemic treatment. GRP78 values were compared between the 2 groups, and prior to and following systemic treatment. Association analyses between GRP78 expression and prognostic markers were also performed. Cox regression analysis was used to examine the impact of these variables on disease-free survival (DFS). No differences in cytoplasmic GRP78 expression were observed. By contrast, the rates of cell surface GRP78 expression were 74.1% in the early stage operable patients, 36% in neoadjuvant systemic treatment patients prior to treatment and 62.5% in patients following systemic treatment (P<0.039). Positive cell surface GRP78 expression was associated with increased expression of the progesterone receptor (P=0.024), p53 expression (P=0.022) and improved DFS (P=0.047). In the case of GRP78 positivity, a trend for a superior response to chemotherapy was observed (P=0.19). The results of the present study indicated that cell surface GRP78 may be used as a marker for good prognosis in breast cancer and a potential marker for response to chemotherapy.

Serum GRP78 as a Tumor Marker and Its Prognostic Significance in Non-Small Cell Lung Cancers: A Retrospective Study

INTRODUCTION

Glucose-regulated protein 78 (78 kDa, GRP78), which is also known as immunoglobulin heavy chain binding protein (BIP), is a major chaperone in the endoplasmic reticulum (ER). The expression and clinical significance of GRP78 in the serum of non-small cell lung cancer patients have not yet been clearly described. The aims of the present study were to investigate the expression of GRP78 in the serum of non-small cell lung cancer patients, the relationships with clinicopathological parameters, and the potential implications for survival.

PATIENTS AND METHODS

A total of 163 peripheral blood samples from non-small cell lung cancer patients were prospectively collected at the Department of Thoracic Surgery, Fudan University Shanghai Cancer, China. Clinical characteristics data, including age, gender, stage, overall survival (OS) time, and relapse-free survival (RFS) time, were also collected. Serum GRP78 levels were measured using a commercially available ELISA kit. The associations between GRP78 levels and clinicopathological characteristics and survival were examined using Student's t-test, Kaplan-Meier, or Cox regression analyses.

RESULTS

The mean ± standard error (SE) value of GRP78 was 326.5 ± 49.77 pg/mL. This level was significantly lower compared with the level in late-stage non-small cell lung cancer patients (1227 ± 223.6, p = 0.0001). There were no significant correlations with the clinicopathological parameters. No significant difference was found between high GRP78 expression and low GRP78 expression with regard to RFS (p = 0.1585). However, the OS of patients with higher GRP78 expression was significantly poorer (p = 0.0334).

CONCLUSIONS

GRP78 was expressed in non-small cell lung cancer patients and was highly enriched in late-stage lung cancer. GRP78 may have an important role in the carcinogenesis of non-small cell lung cancer and may be a prognostic marker for non-small cell lung cancer.

Protein disulfide isomerases: Impact of thapsigargin treatment on their expression in melanoma cell lines

Anti-cancer treatments usually elevate the content of unfolded or misfolded proteins in the endoplasmic reticulum (ER). Here we aimed to get insights into the relation between sensitivity of melanoma cell lines to the ER stress inducer thapsigargin (THG) and the genetic expression of protein disulfide isomerase family members (PDIs). The expression of PDIs was analysed by flow cytometry and real-time PCR. The results showed that SK-MEL-30, the less THG sensitive cell line, displays higher basal PDIs' expression levels and the sensitivity is increased by the PDIs inhibitor bacitracin. While SK-MEL-30 PDIs' expression is not THG dose-dependent, an increase in glucose related protein 78 (GRP78), PDIA5, PDIA6, and thioredoxin-related-transmembrane proteins' (TMX3 and TMX4) expression, in response to higher drug concentrations, was observed in MNT-1. The differences in PDIs' gene expression in MNT-1 suggest a different response to ER stress compared to the other cell lines and highlight the importance of understanding the diversity among cancer cells.

MDA-9 and GRP78 as potential diagnostic biomarkers for early detection of melanoma metastasis

Metastatic melanoma, the primary cause of skin cancer-related death, warrants new diagnostic and therapeutic approaches that target the regulatory machinery at molecular level. The heterogeneity and complexity of melanoma result in the difficulty to find biomarkers and targets for early detection and treatment. Here, we investigated metastasis-associated proteins by comparing the proteomic profiles of primary cutaneous melanomas to their matched lymph node metastases, which minimizes heterogeneity among samples from different patients. Results of two-dimensional gel electrophoresis (2-DE) followed by proteomic analysis revealed eight differentially expressed proteins. Among them, seven proteins (α-enolase, cofilin-1, LDH, m-β-actin, Nm23, GRP78, and MDA-9) showed increased and one (annexin A2) showed decreased expression in metastatic lymph node tissues than in primary melanomas. MDA-9 and GRP78 were the most highly expressed proteins in lymph node metastases, which was validated by immunohistochemical staining. Moreover, exosomes from serum samples of metastatic melanoma patients contained higher levels of MDA-9 and GRP78 than those of patients without metastases, indicating the potential of MDA-9 and GRP78 to be biomarkers for early detection of metastasis. Further, small interfering RNA (siRNA)-mediated knockdown confirmed a functional role for MDA-9 and GRP78 to promote cell invasion in the A375 cells. Finally, we showed that GRP78 co-localized with MDA-9 in 293T cells. Taken together, our findings support MDA-9, co-expressed with GRP78, as a melanoma protein associated with lymph node metastasis. Investigating how MDA-9 and GRP78 interact to contribute to melanoma metastasis and disease progression could reveal new potential avenues of targeted therapy and/or useful biomarkers for diagnosis and prognosis.

Cytotoxic effect of fluvastatin on MCF-7 cells possibly through a reduction of the mRNA expression levels of SGK1 and CAV1

Fluvastatin (FLU) prevents the conversion of 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) to mevalonic acid by inhibiting HMG-CoA reductase and decreases cholesterol level. Although the effects of FLU treatment on several cancer types through many mechanisms have been identified, its relationship with unfolded protein response and apoptosis has not been clearly understood. In this recent study, we aimed to investigate the cytotoxic effect of Fluvastatin on MCF-7 cells and define the transcriptional regulation of specific genes during the occurrence of this cytotoxic effect. We administered 0.62, 2.5, 5, and 40 μM FLU on MCF-7 cells singly and in combination with 2-deoxyglucose (2-DG), and we monitored cell viability and proliferation for 48 hours using real-time cell analyzer system (xCELLigence). At the same time, we measured the mRNA expression levels of glucose-regulated protein 78 (GRP78), CCAAT/enhancer binding protein, homologous protein (CHOP), caveolin-1 (CAV1), NDRG1 Variant 1 and Variant 2, HMOX1, SGK1, and prostate apoptosis response-4 (PAR4) genes using quantitative real-time polymerase chain reaction (LightCycler 480 II). We accepted GAPDH gene and control groups as the reference gene and calibrator, respectively. We performed relative gene expression analyses of the study groups using the QIAGEN 2009 Relative Expression Software Tool (REST). FLU revealed an antiproliferative and cytotoxic effect on MCF-7 cells, while causing the transcriptional regulation of many genes. Of these genes, the mRNA expressions of CHOP, heme oxygenase 1 (HMOX1), N-myc downstream-regulated gene 1 (NDRG1) V1, and NDRG1 V2 increased. On the other hand, the mRNA expression levels of SGK1 and CAV1 decreased. The antiproliferative effects of FLU may be related to the decreased expression levels of SGK1 and CAV1.

Endoplasmic reticulum chaperones and oxidoreductases: critical regulators of tumor cell survival and immunorecognition

Endoplasmic reticulum (ER) chaperones and oxidoreductases are abundant enzymes that mediate the production of fully folded secretory and transmembrane proteins. Resisting the Golgi and plasma membrane-directed “bulk flow,” ER chaperones and oxidoreductases enter retrograde trafficking whenever they are pulled outside of the ER by their substrates. Solid tumors are characterized by the increased production of reactive oxygen species (ROS), combined with reduced blood flow that leads to low oxygen supply and ER stress. Under these conditions, hypoxia and the unfolded protein response upregulate their target genes. When this occurs, ER oxidoreductases and chaperones become important regulators of tumor growth. However, under these conditions, these proteins not only promote the folding of proteins, but also alter the properties of the plasma membrane and hence modulate tumor immune recognition. For instance, high levels of calreticulin serve as an “eat-me” signal on the surface of tumor cells. Conversely, both intracellular and surface BiP/GRP78 promotes tumor growth. Other ER folding assistants able to modulate the properties of tumor tissue include protein disulfide isomerase (PDI), Ero1α and GRP94. Understanding the roles and mechanisms of ER chaperones in regulating tumor cell functions and immunorecognition will lead to important insight for the development of novel cancer therapies.

Glucose-regulated protein 78 and heparanase expression in oral squamous cell carcinoma: correlations and prognostic significance

BACKGROUND

The aim of the present study was to investigate the expression of glucose-related protein 78 (GRP78) and heparanase (HPA) in oral squamous cell carcinoma (OSCC) and their relationship with clinicopathological parameters and potential implications for survival.

METHODS

A total of 46 patients with OSCC and 10 normal individuals were recruited for the study. GRP78 and HPA expression were determined in the lesion tissues using immunohistochemical analysis. The correlation between GRP78 and HPA was assessed using the Spearman correlation analysis. The associations of GRP78 and HPA with clinicopathological characteristics and survival were examined using the x2-test, Kaplan-Meier, or Cox regression.

RESULTS

Patients with OSCC showed a statistically significant higher prevalence of GRP78 and HPA expression than normal oral tissues. GRP78 and HPA expression was positively correlated with size, TNM stage, histological grade, lymphatic metastasis, and distant metastasis in OSCC patients. GRP78 expression was also positively correlated with HPA expression. Positive GRP78 and HPA expression was inversely correlated with survival in OSCC patients.

CONCLUSIONS

HPA expression was found to be positively correlated with GRP78 expression. GRP78 and HPA are biomarkers that may have the potential to guide the treatment of oral cancer patients.

Autoantibodies against cell surface GRP78 promote tumor growth in a murine model of melanoma

Autoantibodies that react with GRP78 expressed on the cell-surface of many tumor cell lines occur in the sera of patients with prostate cancer, melanoma, and ovarian cancer. These autoantibodies are a negative prognostic factor in prostate cancer and, when purified, stimulate tumor cell proliferation in vitro. It is unclear, however, whether these immunoglobulin Gs are merely a biomarker, or whether they actually promote the tumor growth in vivo. We immunized C57Bl/6 mice with recombinant GRP78 and then implanted the B16F1 murine melanoma cell line as flank tumors. We used the antisera from these mice for in-vitro cell signaling and proliferation assays. The immunodominant epitope in patients with cancer was well represented in the antibody repertoire of these immunized mice. We observed significantly accelerated tumor growth, and shortened survival in GRP78-immunized mice compared with controls. Furthermore, antisera from these mice, and purified anti-GRP78 immunoglobulin G from similarly immunized mice, stimulate Akt phosphorylation and proliferation in B16F1 and human DM6 melanoma cells in culture. These studies show a causal link between a humoral response to GRP78 and the progression of cancer in a murine melanoma model. They support the hypothesis that such autoantibodies are involved in the progression of human cancers and are not simply a biomarker. As GRP78 is present on the surface of many types of cancer cells, this hypothesis has broad clinical and therapeutic implications.

Association of elevated GRP78 expression with increased astrocytoma malignancy via Akt and ERK pathways

Unlike other members of HSP70 family, GRP78 manifests multifaceted subcellular distribution and forms complex with different signals, resulting in its close correlation with various tumors. However, its expression profile and function in glioma remain less well defined. In this study, normal brain tissue and astrocytic tumor specimens were evaluated for GRP78 expression, which was shown to be up-regulated in astrocytoma compared with normal tissue, increased markedly as astrocytoma pathologic grade escalates, and can still be enhanced for disease recurrence. By employing Cox regression analyses, high GRP78 expression was correlated with a poorer outcome for recurrent glioblastoma patients. In addition, immunofluorescence microscopy detected cell surface positioning of GRP78 on human glioma cells. After transfection with siRNA or antibody ligation of surface GRP78, phosphorylation of Akt and ERK was attenuated. These findings indicate that GRP78 plays an important role in astrocytoma malignancy, whereas its cell surface localization may be attractive for clinical utilization.

Roles of GRP78 in physiology and cancer

As one member of 70 kDa heat shock proteins, glucose-regulated protein 78 (GRP78) participates in protein folding, transportation and degradation. This sort of capacity can be enhanced by stresses under which GRP78 is induced rapidly. Unlike its homologues, GRP78 presents multifaceted subcellular position: When ER retention, it serves as the switch of unfolded protein response; When mitochondrial binding, it directly interacts with apoptotic executors; When cell surface residing, it recognizes extracellular ligands, transducing proliferative signals, especially in certain tumors. The close correlation between GRP78 and neoplasm provides us further insight into the event of carcinogenesis and cancer cell chemoresistance, indicating its prognostic predicting significance and validating potential therapeutics for clinical usage, especially because its small molecular inhibitors are emerging quickly these years. What's more, GRP78-related signaling may be helpful for clearer understanding of its biological mechanisms.