Expression and release of glucose-regulated protein-78 (GRP78) in multiple myeloma (original) (raw)
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Significance of GRP78 expression in acute myeloid leukemias
Open Medicine, 2014
The GRP78 (glucose-regulated protein 78) is a major endoplasmic reticulum (ER) chaperone facilitating proper folding of the newly synthesized proteins. By the interaction with caspases, GRP78 has antiapoptotic properties allowing cells to survive under stress condition. GRP78 expression and its association with tumor proliferation, metastasis and resistance to chemotherapy were observed in solid tumors. There are limited data on the expression and impact of this protein on the clinical course and treatment response in acute myeloid leukemia (AML). The aim of this study was to evaluate the expression of GRP78 mRNA in patients with de novo AML. These results were compared to healthy controls, blast phenotype, molecular and cytogenetic status and clinical features of AML. 101 non-M3 AML patients and 26 healthy individuals were included in this study. The expression of GRP78 mRNA in bone marrow was analyzed by real-time quantitative polymerase chain reaction (RQ-PCR). We demonstrated increased GRP78 mRNA expression in AML patients compared to healthy controls, although this difference was statistically significant only in CD34 + leukemias. There was also no significant correlation between GRP78 mRNA expression and complete remission rate, relapse-free survival and overall survival. These results indicate that GRP78 expression is increased in CD34 + leukemias and has no prognostic impact on clinical outcome in AML.
Clinical cancer research : an official journal of the American Association for Cancer Research, 2016
Glucose-regulated protein (GRP) 78 is overexpressed in multiple myeloma (MM) and both, its surface expression as well as its biological significance as key sensor of the unfolded protein response make GRP78 an ideal candidate for immunotherapeutic intervention. The monoclonal antibody PAT-SM6 targets surface (s) GRP78 and leads to disease stabilization when used as single-agent in a clinical trial. In this paper, we evaluated expression of GRP78 in relapsed-refractory disease and explored PAT-SM6 therapy in combination regimens. GRP78 expression was immunohistochemically analyzed during disease progression and development of drug resistance throughout different stages of MM. Activity of PAT-SM6 was evaluated in combination with anti-MM agents lenalidomide, bortezomib and dexamethasone in vitro. Finally, we report on a MM patient with relapsed and refractory disease treated with PAT-SM6 in combination with bortezomib and lenalidomide. Although sGRP78 expression was present at all sta...
Cancer research, 1993
Tumor cells undergo self-destruction when incubated with cytotoxic T-cells (CTL) consistent with the observation that suppression of target protein synthesis causes resistance to apoptosis. Resistance to CTL is also induced by stress, suggesting that pathways exist suppressing apoptosis. Here we examine whether stress induced lysis resistance to CTL and tumor necrosis factor alpha involves stress proteins GRP78 and GRP94. We show that inhibition of GRP78 synthesis by transfection of cells with grp78 antisense vector pRSV-78WO leads to inability to induce resistance to CTL or tumor necrosis factor alpha. Resistance induced in untransfected cells is reversible upon stress removal and correlates with GRP78 rephosphorylation, consistent with the notion that phosphorylated GRP78 is nonfunctional. The possibility that GRP78 plays a role in defense against CTL mediated apoptosis is supported by the finding that CTL but not CD4+ cells express a high level of unphosphorylated GRP78.
PloS one, 2014
This study was designed to investigate the activation of the unfolded protein response (UPR) in tumor associated endothelial cells (TECs) and its association with chemoresistance during acidic pH stress. Endothelial cells from human oral squamous cell carcinomas (OSCC) were excised by laser capture microdissection (LCM) followed by analysis of UPR markers (Grp78, ATF4 and CHOP) using quantitative PCR. Grp78 expression was also determined by immunostaining. Acidic stress was induced in primary human dermal microvascular endothelial cells (HDMECs) by treatment with conditioned medium (CM) from tumor cells grown under hypoxic conditions or by adjusting medium pH to 6.4 or 7.0 using lactic acid or hydrochloric acid (HCl). HDMEC resistance to the anti-angiogenic drug Sunitinib was assessed with SRB assay. UPR markers, Grp78, ATF4 and CHOP were significantly upregulated in TECs from OSCC compared to HDMECs. HDMECs cultured in acidic CM (pH 6.0-6.4) showed increased expression of the UPR m...
Biochemical Journal, 2011
GRP78 (glucose-regulated protein of 78 kDa) is traditionally regarded as a major ER (endoplasmic reticulum) chaperone facilitating protein folding and assembly, protein quality control, Ca2+ binding and regulating ER stress signalling. It is a potent anti-apoptotic protein and plays a critical role in tumour cell survival, tumour progression and angiogenesis, metastasis and resistance to therapy. Recent evidence shows that GRP78 can also exist outside the ER. The finding that GRP78 is present on the surface of cancer but not normal cells in vivo represents a paradigm shift on how GRP78 controls cell homoeostasis and provides an opportunity for cancer-specific targeting. Cell-surface GRP78 has emerged as an important regulator of tumour cell signalling and viability as it forms complexes with a rapidly expanding repertoire of cell-surface protein partners, regulating proliferation, PI3K (phosphoinositide 3-kinase)/Akt signalling and cell viability. Evidence is also emerging that GRP7...
A new tumor-specific variant of GRP78 as target for antibody-based therapy
Laboratory Investigation, 2008
The chaperone GRP78 is a member of the heat-shock protein 70 (HSP70) family and is responsible for cellular homeostasis by preventing stress-induced apoptosis. GRP78 is expressed in all cells of the body. In malignant cells, which are permanently exposed to environmental stress, GRP78 is overexpressed and increased levels can be found in the cytoplasm and on the cell membrane. Thus, GRP78 promotes tumor proliferation, survival, metastases and resistance to a wide variety of therapies. Like other tumor-specific membrane molecules, GRP78 can also be present on cancer cells in a variant form. This modification qualifies it as a target for immune surveillance and antibody responses. The fully human monoclonal IgM antibody, SAM-6, was isolated from a gastric cancer patient and it binds to a new variant of GRP78 with a molecular weight of 82 kDa. The epitope is an O-linked carbohydrate moiety and is specific for malignant cells. These data show that cancer-specific modifications of cell-surface protection molecules are (a) subject of an immune response and (b) ideal targets for new therapeutical approaches.
Expression of glucose‐regulated stress protein GRP78 is related to progression of melanoma
2009
Aims: Glucose-regulated protein 78 (GRP78) is a protein translated in response to endoplasmic reticulum (ER) stress that has been implicated in the pathogenesis and resistance to therapy of a variety of cancers. The aim of this study was to investigate its expression and role in the development and progression of human melanoma. Methods and results: The immunohistochemical expression of GRP78 in naevi, primary melanoma and melanoma metastases from 171 patients was correlated with clinicopathological factors and patient survival. The GRP78 immunoreactivity score (IRS) was 0.2 in compound naevi, 0.65 in dysplastic naevi, 4.65 in naevi adjacent to primary melanoma, 2.4 in melanoma in situ, 11.2 in thin (£1.0 mm) and 18.1 in thick (>1.0 mm) primary melanoma. It was 18 and 17.3 in subcutaneous and lymph node metastases, respectively (P < 0.0001). GRP78 expression was positively correlated with increasing tumour thickness (P = 0.001) and with increasing dermal tumour mitotic index (P = 0.0004). Disease-free survival (v 2 = 8.0703, P = 0.0045) and overall survival (v 2 = 6.2633, P = 0.0123) in melanoma patients with IRS >25 were significantly lower than in melanoma patients with IRS <25. Conclusions: GRP78 expression appears to correlate with known correlates of melanoma progression and survival and requires further evaluation as a prognostic biomarker in melanoma.
Cancer Research, 2006
Circulating autoantibodies against the glucose-regulated protein of 78 kDa (GRP78) are present at high levels in prostate cancer patients and are a biomarker of aggressive tumor behavior. We purified the anti-GRP78 IgGs and examined their effect on 1-LN, PC-3, DU145, and LnCap human prostate cancer cells. We also evaluated its effects on the breast cancer MDA-MB231 and melanoma DM413 cell lines. The anti-GRP78 antibody binds only to cells expressing GRP78 on the surface, to a site also recognized by its physiologic agonist, activated A 2 -macroglobulin (A 2 M*). This antibody is completely specific for a peptide, including the primary amino acid sequence CNVKSDKSC, which contains a tertiary structural motif mimicking an epitope in GRP78. Tertiary structual analysis suggested the linear GRP78 primary amino acid sequence LIGRTWNDPSVQQDIKFL (Leu 98 -Leu 115 ) as the putative binding site, containing the tertiary structual arrangement described above, which was confirmed experimentally. The anti-GRP78 antibodies from prostate cancer patients recognize almost exclusively this epitope. We produced animal antibodies against both these peptides, and they are able to mimic the effects of the human antibody. Our experiments also suggest this epitope as highly immunogenic, thereby explaining the specificity of the immune response against this epitope in GRP78, observed in humans. Using 1-LN cells as a model, we show that anti-GRP78 IgG purified from the sera of these patients mimics the proproliferative effects induced by A 2 M* via the common receptor, GRP78. Furthermore, increasing concentrations of human anti-GRP78 IgG show a dose-dependent protective effect on apoptosis induced by tumor necrosis factor A.