Glucose-regulated protein 94 is a novel glioma biomarker and promotes the aggressiveness of glioma via Wnt/β-catenin signaling pathway

Cellular stress responses as modulators of drug cytotoxicity in pharmacotherapy of glioblastoma

Despite the extensive efforts to find effective therapeutic strategies, glioblastoma (GBM) remains a therapeutic challenge with dismal prognosis of survival. Over the last decade the role of stress responses in GBM therapy has gained a great deal of attention, since depending on the duration and intensity of these cellular programs they can be cytoprotective or promote cancer cell death. As such, initiation of the UPR, autophagy or oxidative stress may either impede or facilitate drug-mediated cell killing. In this review, we summarize the mechanisms that regulate ER stress, autophagy, and oxidative stress during GBM development and progression to later discuss the involvement of these stress pathways in the response to different treatments. We also discuss how a precise understanding of the molecular mechanisms regulating stress responses evoked by different pharmacological agents could decisively contribute to the design of novel and more effective combinational treatments against brain malignancies.

HSP90B1-mediated plasma membrane localization of GLUT1 promotes radioresistance of glioblastomas

Ionizing radiation is a popular and effective treatment option for glioblastoma (GBM). However, resistance to radiation therapy inevitably occurs during treatment. It is urgent to investigate the mechanisms of radioresistance in GBM and to find ways to improve radiosensitivity. Here, we found that heat shock protein 90 beta family member 1 (HSP90B1) was significantly upregulated in radioresistant GBM cell lines. More importantly, HSP90B1 promoted the localization of glucose transporter type 1, a key rate-limiting factor of glycolysis, on the plasma membrane, which in turn enhanced glycolytic activity and subsequently tumor growth and radioresistance of GBM cells. These findings imply that targeting HSP90B1 may effectively improve the efficacy of radiotherapy for GBM patients, a potential new approach to the treatment of glioblastoma.

The biology and inhibition of glucose-regulated protein 94/gp96

The 94 kDa molecular chaperone, glucose-regulated protein 94 (Grp94), has garnered interest during the last decade due to its direct association with endoplasmic reticulum (ER) stress and disease. Grp94 belongs to the Hsp90 family of molecular chaperones and is a master regulator of ER homeostasis due to its ability to fold and stabilize proteins/receptors, and to chaperone misfolded proteins for degradation. Multiple studies have demonstrated that Grp94 knockdown or inhibition leads to the degradation of client protein substrates, which leads to disruption of disease-dependent signaling pathways. As a result, small molecule inhibitors of Grp94 have become a promising therapeutic approach to target a variety of disease states. Specifically, Grp94 has proven to be a promising target for cancer, glaucoma, immune-mediated inflammation, and viral infection. Moreover, Grp94-peptide complexes have been utilized effectively as adjuvants for vaccines against a variety of disease states. This work highlights the significance of Grp94 biology and the development of therapeutics that target this molecular chaperone in multiple disease states.

A Pan-Cancer Analysis of Heat-Shock Protein 90 Beta1(HSP90B1) in Human Tumours

Background: HSP90B1, a member of the heat-shock protein 90 family, plays a vital role as a molecular chaperone for oncogenes and stimulates tumour growth. However, its role in various cancers remains unexplored. Methods: Using the cancer genome atlas, gene expression omnibus the Human Protein Atlas databases and various other bioinformatic tools, this study investigated the involvement of HSP90B1 in 33 different tumour types. Results: The over-expression of HSP90B1 generally predicted poor overall survival and disease-free survival for patients with tumours, such as adrenocortical carcinoma, bladder urothelial carcinoma, kidney renal papillary cell carcinoma, and lung adenocarcinoma. In this study, HSP90B1 was highly expressed in the majority of tumours. A comparison was made between the phosphorylation of HSP90B1 in normal and primary tumour tissues, and putative functional mechanisms in HSP90B1-mediated oncogenesis were investigated. Additionally, the mutation burden of HSP90B1 in cancer was evaluated along with the survival rate of patients with cancer patients. Conclusion: This first pan-cancer investigation reveals the oncogenic functions of HSP90B1 in various cancers.

gp96 Expression in Gliomas and Its Association with Tumor Malignancy and T Cell Infiltrating Level

Heat shock protein glycoprotein 96 kDa (gp96) implicates in glioma invasiveness and engages antitumor immune response, representing a potential target for glioma treatment. However, its expression in different types of gliomas, its association with glioma-infiltrating T cells (GITs), and their clinical significance remain unknown. Herein, we utilized multiplex immunofluorescence staining (MIS) to detect gp96 expression and GIT levels on a tissue microarray (TMA), that comprises 234 glioma cases. We then validated the TMA results and explored possible mechanisms by investigating the RNA-seq data from The Cancer Genome Atlas (TCGA) and the Chinese Glioma Genome Atlas (CGGA). We observed that gp96 was ubiquitously expressed in all types of gliomas whereas overexpressed in grade IV gliomas. Also, high gp96 expression predicted unfavorable outcomes independent of the malignancy grade. Meanwhile, gp96 expression positively correlated CD8⁺, CD4⁺, and PD-1⁺ cell densities, and especially associated with increased infiltration of CD4⁺ PD-1⁺ GITs. Clinically, the gp96-immune cell score (GI score), by summing the values measuring gp96 expression and immune cell densities, is capable of stratifying patients into four outcome-distinct groups (hazard ratio, 1.945; 95% CI, 1.521–2.486; P < 0.0001). Mechanistically, the interferon-γ/α response pathways were revealed to engage in the association between gp96 and GITs. Taken together, gp96 was ubiquitously expressed in gliomas, overexpressed in grade IV gliomas, and increased with GIT infiltrative levels. The GI score, that integrates levels of gp96 expression and GIT infiltration, is a potential prognostic classification system for gliomas.

Molecular Chaperone GRP94/GP96 in Cancers: Oncogenesis and Therapeutic Target

During tumor development and progression, intrinsic and extrinsic factors trigger endoplasmic reticulum (ER) stress and the unfolded protein response, resulting in the increased expression of molecular chaperones to cope with the stress and maintain tumor cell survival. Heat shock protein (HSP) GRP94, also known as GP96, is an ER paralog of HSP90 and has been shown to promote survival signaling during tumor-induced stress and modulate the immune response through its multiple clients, including TLRs, integrins, LRP6, GARP, IGF, and HER2. Clinically, elevated expression of GRP94 correlates with an aggressive phenotype and poor clinical outcome in a variety of cancers. Thus, GRP94 is a potential molecular marker and therapeutic target in malignancies. In this review, we will undergo deep molecular profiling of GRP94 in tumor development and summarize the individual roles of GRP94 in common cancers, including breast cancer, colon cancer, lung cancer, liver cancer, multiple myeloma, and others. Finally, we will briefly review the therapeutic potential of selectively targeting GRP94 for the treatment of cancers.

Cell Surface GRP94 as a Novel Emerging Therapeutic Target for Monoclonal Antibody Cancer Therapy

Glucose-regulated protein 94 (GRP94) is an endoplasmic reticulum (ER)-resident member of the heat shock protein 90 (HSP90) family. In physiological conditions, it plays a vital role in regulating biological functions, including chaperoning cellular proteins in the ER lumen, maintaining calcium homeostasis, and modulating immune system function. Recently, several reports have shown the functional role and clinical relevance of GRP94 overexpression in the progression and metastasis of several cancers. Therefore, the current review highlights GRP94’s physiological and pathophysiological roles in normal and cancer cells. Additionally, the unmet medical needs of small chemical inhibitors and the current development status of monoclonal antibodies specifically targeting GRP94 will be discussed to emphasize the importance of cell surface GRP94 as an emerging therapeutic target in monoclonal antibody therapy for cancer.

Characterizing Cell Stress and GRP78 in Glioma to Enhance Tumor Treatment

Glioblastoma (GBM) is the most common primary brain tumor, carrying a very poor prognosis, with median overall survival at about 12 to 15 months despite surgical resection, chemotherapy with temozolomide (TMZ), and radiation therapy. GBM recurs in the vast majority of patients, with recurrent tumors commonly displaying increase in resistance to standard of care chemotherapy, TMZ, as well as radiotherapy. One of the most commonly cited mechanisms of chemotherapeutic and radio-resistance occurs via the glucose-regulated protein 78 (GRP78), a well-studied mediator of the unfolded protein response (UPR), that has also demonstrated potential as a biomarker in GBM. Overexpression of GRP78 has been directly correlated with malignant tumor characteristics, including higher tumor grade, cellular proliferation, migration, invasion, poorer responses to TMZ and radiation therapy, and poorer patient outcomes. GRP78 expression is also higher in GBM tumor cells upon recurrence. Meanwhile, knockdown or suppression of GRP78 has been shown to sensitize cells to TMZ and radiation therapy. In light of these findings, various novel developing therapies are targeting GRP78 as monotherapies, combination therapies that enhance the effects of TMZ and radiation therapy, and as treatment delivery modalities. In this review, we delineate the mechanisms by which GRP78 has been noted to specifically modulate glioblastoma behavior and discuss current developing therapies involving GRP78 in GBM. While further research is necessary to translate these developing therapies into clinical settings, GRP78-based therapies hold promise in improving current standard-of-care GBM therapy and may ultimately lead to improved patient outcomes.

Immunotherapy with heat shock protein 96 to treat gliomas

Heat shock protein 96 (gp96) is a highly conserved protein in the endoplasmic reticulum. The functions of gp96 include promoting the oncogenesis and progression of glioma. In addition, tumor-derived gp96 can activate anti-tumor immune. Therefore, this protein was used to generate an anti-tumor vaccine and widely applied to glioma therapy. This review summarizes the mechanisms of gp96 in glioma oncogenesis and clinical trials of the gp96 tumor vaccine in glioma treatment.

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

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

Proteomics Study of Mesenchymal Stem Cell-Like Cells Isolated from Cerebrospinal Fluid of Patients with Meningioma

Background:

Cerebrospinal fluid (CSF) contains pro-growth factors that can affect proliferation, migration and differentiation of Mesenchymal Stem Cells (MSCs).

Objective:

This study aimed to isolate MSC like cells from CSF of patients with meningioma and psudotumorcerebri (PTC) and identify differentially expressed proteins in these cells.

Methods:

Five patients with newly diagnosed intracranial meningioma and five patients with PTC were recruited in this comparative proteomics study. MSCs were isolated from CSF and validated by mesenchyml and non-mesenchyml fluorochrome antibodies, and flow cytometer analysis. Two- Dimensional Gel Electrophoresis (2-DE) coupled with Mass Spectrometry (MS) was performed to identify differentially expressed proteins.

Results:

Microscopic views of the isolated cells as well as flow cytometer analysis were found to be compatible with MSC-like cells. Eight distinct protein spots were differentially and reproducibly expressed among the stained gels of two studied groups. The identified proteins were Phosphoglycerate Mutase 1 (PGAM1), LIM and SH3 domain protein (LASP1), peroxiredoxin-6 (PRDX-6), type I cytoskeletal 9 (KRT9), Superoxide Dismutase (SOD), endoplasmin, Stathmin 1 (STMN1), and glutathione S-transferase (GST).

Conclusion:

This study provides new insights into the plausible role of CSF derived MSCs in cancer progression, and reveals a promising therapeutic opportunity for targeting of MSC proteins in patients with meningioma.

Myosin Heavy Chain 10 (MYH10) Gene Silencing Reduces Cell Migration and Invasion in the Glioma Cell Lines U251, T98G, and SHG44 by Inhibiting the Wnt/β-Catenin Pathway

Background

The myosin heavy chain 10 or MYH10 gene encodes non-muscle myosin II B (NM IIB), and is involved in tumor cell migration, invasion, extracellular matrix (ECM) production, and epithelial-mesenchymal transition (EMT). This study aimed to investigate the effects of the MYH10 gene on normal human glial cells and glioma cell lines in vitro, by gene silencing, and to determine the signaling pathways involved.

Material/Methods

The normal human glial cell line HEB, and the glioma cell lines, U251, T98G, and SHG44 were studied. Plasmid transfection silenced the MYH10 gene. The cell counting kit-8 (CCK-8) assay evaluated cell viability. Cell migration and invasion were evaluated using scratch and transwell assays. Western blot measured the protein expression levels, and quantitative real-time polymerase chain reaction (qRT-PCR) was used to detect the mRNA expression levels, for MYH10, metastasis-associated protein 1 (MTA-1), matrix metalloproteinase (MMP)-1, MMP-9, tissue inhibitor of metalloproteinases 2 (TIMP2), collagen 1, E-cadherin, vimentin, Wnt3a, β-catenin, and cyclin D1.

Results

The MYH10 gene was overexpressed in U251, T98G, and SHG44 cells. MYH10 expression was down-regulated following siMYH10 plasmid interference, which also inhibited glioma cell migration and invasion. MYH10 gene silencing resulted in reduced expression of MTA-1, MPP-2, MMP-9 and vimentin, and increased expression of TIMP-2, E-cadherin and collagen 1 at the protein and mRNA level, and inhibited the Wnt/β-catenin pathway.

Conclusions

In human glioma cell lines, silencing the MYH10 gene reduced cell migration and invasion, by inhibiting the Wnt/β-catenin pathway, which may regulate the ECM and inhibit EMT in human glioma.

Grp94 in complexes with IgG is a soluble diagnostic marker of gastrointestinal tumors and displays immune-stimulating activity on peripheral blood immune cells

Glucose-regulated protein94 (Grp94), the most represented endoplasmic reticulum (ER)-resident heat shock protein (HSP), is a tumor antigen shared by different types of solid and hematological tumors. The tumor-specific feature of Grp94 is its translocation from the ER to the cell surface where it displays pro-oncogenic functions. This un-physiological location has important implications for both the tumor pathology and anti-tumor therapy. We wanted to address the question of whether Grp94 could be measured as liquid marker in cancer patients in order to make predictions of diagnostic and therapeutic relevance for the tumor. To this aim, we performed an in-depth investigation on patients with primary tumors of the gastrointestinal (GI) tract, using different methodological approaches to detect Grp94 in tumor tissues, plasma and peripheral blood mononuclear cells (PBMCs). Results indicate that Grp94 is not only the antigen highly expressed in any tumor tissue and in cells of tumor infiltrates, mostly B lymphocytes, but it is also found in the circulation. However, the only form in which Grp94 was detected in the plasma of any patients and in B lymphocytes induced to proliferate, was that of stable complexes with Immunoglobulin (Ig)G. Using a specific immune-enzyme assay to measure plasma Grp94-IgG complexes, we showed that Grp94-IgG complexes were significantly increased in cancer patients compared to healthy control subjects, serving as diagnostic tumor biomarker. Results also demonstrate that the stimulation of patient PBMCs with Grp94-IgG complexes led to an increased secretion of inflammatory cytokines that might drive a potentially beneficial anti-tumor effect.

Second Generation Grp94-Selective Inhibitors Provide Opportunities for the Inhibition of Metastatic Cancer

Glucose regulated protein 94 (Grp94) is the endoplasmic reticulum (ER) resident isoform of the 90 kDa heat shock protein (Hsp90) family and its inhibition represents a promising therapeutic target for the treatment of many diseases. Modification of the first generation cis-amide bioisostere imidazole to alter the angle between the resorcinol ring and the benzyl side chain via cis-amide replacements produced compounds with improved Grp94 affinity and selectivity. Structure-activity relationship studies led to the discovery of compound 30, which exhibits 540 nm affinity and 73-fold selectivity towards Grp94. Grp94 is responsible for the maturation and trafficking of proteins associated with cell signaling and motility, including select integrins. The Grp94-selective inhibitor 30 was shown to exhibit potent anti-migratory effects against multiple aggressive and metastatic cancers.

Comparative Proteomic Analysis of Tumor Mesenchymal-Like Stem Cells Derived from High Grade versus Low Grade Gliomas

Objective

Gliomas are the most common primary brain tumors, and have been ranked as the fourth leading cause of cancer death. Tumor mesenchymal-like stem cells (tMSCs) contribute to the aggressive behavior of glial tumors by providing a favorable microenvironment for the malignant cells. The aim of our study was to identify differential proteome of tMSCs derived from low vs. high grade glioma tumors.

Materials and Methods

Patients with newly diagnosed low and high grade gliomas were included in this case control study. tMSCs were isolated from tumors using enzymatic digestion validated by flow cytometer analysis after sub-culturing. Differential proteomic analysis of tMSCs derived from low and high grade tumors was performed by two-dimensional gel electrophoresis and mass spectrometry. Protein spots with more than two fold differences and P values below 0.05 were considered as differentially expressed ones.

Results

In tMSCs isolated from low and high grade gliomas, different isoforms of mesenchymal-related proteins vimentin and transgelin were differentially expressed. Overexpressed proteins in tMSCs isolated from low grade gliomas were mitochondrial manganese-containing superoxide dismutase (Mn-SOD), 40S ribosomal protein SA, and GTP-binding nuclear protein, while in tMSCs isolated from high grade gliomas, cathepsin B, endoplasmin, ezrin, peroxiredoxin1, and pyruvate kinase (PK) were found to be significantly overexpressed.

Conclusion

For the first time, we analyzed the differential proteomic profiles of tMSCs isolated from glioma tumors with different grades. It was found that molecules related to mesenchymal cells (vimentin and transglin), in addition to those related to tumor aggressiveness with potential secretory behavior (e.g. cathepsin B) were among differentially expressed proteins.

Molecular and cellular effects of a novel hydroxamate-based HDAC inhibitor - belinostat - in glioblastoma cell lines: a preliminary report

Histone deacetylase (HDAC) inhibitors are now intensively investigated as potential cytostatic agents in many malignancies. Here, we provide novel information concerning the influence of belinostat (Bel), a hydroxamate-based pan-HDAC inhibitor, on glioblastoma LN-229 and LN-18 cells. We found that LN-229 cells stimulated with 2 μmol/L of Bel for 48 h resulted in 70 % apoptosis, while equivalent treatment of LN-18 cells resulted in only 28 % apoptosis. In LN-229 cells this effect was followed by up-regulation of pro-apoptotic genes including Puma, Bim, Chop and p21. In treated LN-18 cells only p21 was markedly overexpressed. Simultaneously, LN-229 cells treated with 2 μmol/L of Bel for 48 h exhibited down-regulation of molecular chaperones GRP78 and GRP94 at the protein level. In contrast, in LN-18 cells Western blot analysis did not show any marked changes in GRP78 nor GRP94 expression. Despite noticeable overexpression of p21, there were no signs of evident G1 nor G2/M cell cycle arrest, however, the reduction in number of the S phase cells was observed in both cell lines. These results collectively suggest that Bel can be considered as potential anti-glioblastoma agent. To our knowledge this is the first report presenting the effects of belinostat treatment in glioblastoma cell lines.

Glycoprotein non-metastaticmelanoma protein B promotes glioma motility and angiogenesis through the Wnt/β-catenin signaling pathway

Glioma is a common tumor with high mortality and poor overall survival. However, the regulatory mechanisms of glioma tumorigenesis and glioma cell motility are completely unknown. Here, we investigated the role of glycoprotein non-metastatic melanoma protein B in glioma. The expression of glycoprotein non-metastatic melanoma protein B is observed to be aberrantly regulated in glioma tissues and cells, and high levels of glycoprotein non-metastatic melanoma protein B present an inverse correlation with the survival of glioma patients. Compared with the control, glycoprotein non-metastatic melanoma protein B inhibition significantly retarded the proliferation and migration of human glioma cells. The tube formation ability of HBMECs induced by glioma cells was also remarkably reduced by glycoprotein non-metastatic melanoma protein B silencing. Increased levels of VEGF-C and TEM7 were down-regulated by the suppression of glycoprotein non-metastatic melanoma protein B in glioma cells. Additionally, the activity of MMP-2/3/9 was assessed in glioma cells using Western blotting and gelatin zymography assay; their activities were strongly decreased following the suppression of glycoprotein non-metastatic melanoma protein B. Further studies suggested that canonical Wnt/β-catenin pathway was activated, but was inactivated by glycoprotein non-metastatic melanoma protein B suppression in glioma cells. In conclusion, we demonstrate that glycoprotein non-metastatic melanoma protein B might be an inducer for glioma and could enhance matrix metalloproteinase activity through Wnt/β-catenin pathway to contribute to glioma tumorigenesis. This may represent a new understanding for malignant glioma.

Magnetic gold nanoparticle-mediated small interference RNA silencing Bag-1 gene for colon cancer therapy

Bcl-2-associated athanogene 1 (Bag-1) is a positive regulator of Bcl-2 which is an anti-apoptotic gene. Bag-1 was very slightly expressed in normal tissues, but often highly expressed in many tumor tissues, particularly in colon cancer, which can promote metastasis, poor prognosis and anti-apoptotic function of colon cancer. We prepared and evaluated magnetic gold nanoparticle/Bag-1 siRNA recombinant plasmid complex, a gene therapy system, which can transfect cells efficiently, for both therapeutic effect and safety in vitro mainly by electrophoretic mobility shift assays, flow cytometric analyses, cell viability assays, western blot analyses and RT-PCR (real-time) assays. Magnetic gold nanoparticle/Bag-1 siRNA recombinant plasmid complex was successfully transfected into LoVo colon cancer cells and the exogenous gene was expressed in the cells. Flow cytometric results showed apoptosis rate was significantly increased. In MTT assays, magnetic gold nanoparticles revealed lower cytotoxicity than Lipofectamine 2000 transfection reagents (P<0.05). Both in western blot analyses and RT-PCR assays, magnetic gold nanoparticle/Bag-1 siRNA recombinant plasmid complex transfected cells demonstrated expression of Bag-1 mRNA (P<0.05) and protein (P<0.05) was decreased. In further study, c-myc and β-catenin which are main molecules of Wnt/β‑catenin pathway were decreased when Bag-1 were silenced in nanoparticle plasmid complex transfected LoVo cells. These results suggest that magnetic gold nanoparticle mediated siRNA silencing Bag-1 is an effective gene therapy method for colon cancer.