Co-expression of heat shock protein 70 and glucose-regulated protein 94 in human gastric carcinoma cell line BGC-823

The protein-protein interaction network of intestinal gastric cancer patients reveals hub proteins with potential prognostic value

BACKGROUND

Gastric cancer (GC) is the third leading cause of cancer worldwide. According to the Lauren classification, gastric adenocarcinoma is divided into two subtypes: diffuse and intestinal. The development of intestinal gastric cancer (IGC) can take years and involves multiple factors.

OBJECTIVE

To investigate the protein profile of tumor samples from patients with IGC in comparison with adjacent nontumor tissue samples.

METHODS

We used label-free nano-LC-MS/MS to identify proteins from the tissues samples. The results were analyzed using MetaCore™ software to access functional enrichment information. Protein-protein interactions (PPI) were predicted using STRING analysis. Hub proteins were determined using the Cytoscape plugin, CytoHubba. Survival analysis was performed using KM plotter. We identified 429 differentially expressed proteins whose pathways and processes were related to protein folding, apoptosis, and immune response.

RESULTS

The PPI network of these proteins showed enrichment modules related to the regulation of cell death, immune system, neutrophil degranulation, metabolism of RNA and chromatin DNA binding. From the PPI network, we identified 20 differentially expressed hub proteins, and assessed the prognostic value of the expression of genes that encode them. Among them, the expression of four hub genes was significantly associated with the overall survival of IGC patients.

CONCLUSIONS

This study reveals important findings that affect IGC development based on specific biological alterations in IGC patients. Bioinformatics analysis showed that the pathogenesis of IGC patients is complex and involves different interconnected biological processes. These findings may be useful in research on new targets to develop novel therapies to improve the overall survival of patients with IGC.

Canine gastric carcinoma: immunohistochemical expression of cell cycle proteins (p53, p21, and p16) and heat shock proteins (Hsp27 and Hsp70)

Immunohistochemical staining for cell cycle proteins and heat shock proteins was performed on 17 canine gastric carcinomas. The immunoexpression of p53, p21, p16, Hsp27, and Hsp70 was investigated. A study was conducted to determine the histological type and parameters related to tumor malignancy. Possible associations and trends were assessed between the immunoexpression of each protein and tumor type as well as specific parameters of malignancy. High intratumor frequency of cellular p53 immunostaining was observed (61.96% average), but lower frequencies of p21 and p16 expression were present (34.65% and 10.41%, respectively). The p53 overexpression was associated with tumor infiltration (P = .0258). Expression of p21 was lower in undifferentiated carcinomas, and the loss of expression was associated with histopathological parameters characteristic of a poor prognosis such as lymphatic vessel invasion (P = .0258). The lack of p16 immunoreactivity was related to histopathological characteristics of malignancy such as the presence of evident and multiple nucleoli (P = .0475). In contrast, deep tumor infiltration was observed in those carcinomas with a high p16 index (P = .0475). Hsp70 appeared to be overexpressed in all gastric neoplasms included in this study. This is in contrast to Hsp27, because a group of tumors showed complete lack of Hsp27 immunoexpression, whereas the others displayed extensive Hsp27 immunostaining. The differences in Hsp27 did not correlate with any of the histopathological parameters, but Hsp27 immunoexpression was higher in the undifferentiated carcinoma. No significant differences in the expression of the proteins were found in canine gastric carcinomas according to their histological type. These findings may be useful for establishing a prognosis for canine gastric carcinoma.

Correlation between clinicopathology and expression of heat shock protein 72 and glycoprotein 96 in human esophageal squamous cell carcinoma

Heat shock protein 72 (HSP72) and glycoprotein 96 (gp96) are highly expressed in cancer tissues. Recent studies indicate the possible roles of HSP72 and gp96 in the development and progression of gastrointestinal carcinomas but detailed information is still ambiguous. We investigated the correlation between clinicopathology and expression of HSP72 and gp96 in human esophageal squamous cell carcinoma. The expression of HSP72 and gp96 was studied in 120 human esophageal squamous cell carcinomas with or without metastasis as well as in mucous membrane adjacent to cancers by way of immunohistochemistry. HSP72 immunoreactivities were detected in 112 of 120 primary tumors (93.3%) and in 30 of 120 mucous membranes adjacent to cancers (25.0%). Gp96 detected in esophageal squamous cell carcinoma and inmucous membrane adjacent to cancer was 85.0% and 20.0%, respectively. Both HSP72 and gp96 stained in cytoplasm. HSP72 and gp96 expression in esophageal squamous cell carcinomas withmetastasis was significantly higher than those with nonmetastasis (P < .05). The results indicate that there exists a significant correlation between the expression of HSP72 and gp96 and the progression of esophageal squamous cell carcinomas. HSP72 and gp96 expression were significantly associated with the presence of tumor infiltration, lymph node, and remote metastasis.

RNA interference-mediated silencing of the Hsp70 gene inhibits human gastric cancer cell growth and induces apoptosis in vitro and in vivo

AIMS AND BACKGROUND

The role of heat shock protein (HSP) 70 in gastric cancer has been extensively examined in many studies for the past decade. It has been demonstrated that over-expression of Hsp70 might play important role in malignant transformation and maintenance of malignant phenotypes. Therefore, silencing the Hsp70 gene could be applicable in molecular therapies of human gastric cancer. Herein, we designed a small interfering RNA targeting Hsp70 to knock down its expression and investigated its effect on cell proliferation and apoptosis in a gastric cancer cell line.

METHODS

Two plasmids (phsp1-siRNA, phsp2-siRNA), along with a negative control (phsp3-siRNA), were created using a genic recombination technique. BGC823 cell lines were used to perform experiments. Western blotting and RT-PCR were used to detect Hsp70 expression in vitro and in vivo. Cell morphology was observed under light microscope. Cell cycle and apoptosis were analyzed by flow cytometry and acridine orange/ethidium bromide double stain, and cell proliferative activity was measured by alamarblue assay. In all experiments, a negative control served as a baseline measure.

RESULTS

We successfully constructed phsps-siRNA plasmids and transfected them into BGC823 cells. RT-PCR and western blotting revealed that the expression of Hsp70 was down-regulated in transfection groups compared with the control group. Flow cytometric analysis indicated that less S-phase fraction accumulated in small interfering RNA transfected cells than in parental cells and the cells transfected with empty vector.

CONCLUSIONS

Our results demonstrated that RNAi against Hsp70 could effectively knock down gene expression, inhibit growth of cancer cells, induce cell cycle arrest and increase cell apoptosis in vitro and in vivo. Hsp70 might serve as a therapeutic target for human gastric cancer.

HSP70s: From Tumor Transformation to Cancer Therapy

Heat shock proteins (HSPs) are a defined set of chaperones for maintaining proper functions of proteins. The HSP70 family, one of the most inducible families in response to stress, protects cells from stress-induced cell death. It has been documented that HSP70s are highly expressed in various types of cancer cells and make the cells resistant to adverse microenvironments, such as hypoxia and glucose starvation, which are common features in malignant progression. Over-expression of HSP70s is thus associated with tumor transformation and eventually results in a decrease of chemotherapy efficacy. Notably, the distribution of HSP70s is deregulated in cancer cells. It has been reported that HSP70s localize distinct organelles or are exported to humoral circulation during cancer development. Either surface or exported HSP70s play danger signals and trigger immune response to destroy the tumor cells. In this review, we lay out recent advances in the HSP70s-mediated cancer diagnosis and therapy. This review would be enlightening for clinical cancer medicine.

Decreased adhesiveness, resistance to anoikis and suppression of GRP94 are integral to the survival of circulating tumor cells in prostate cancer

The presence of circulating tumor cells (CTC) is common in prostate cancer patients, however until recently their clinical significance was unknown. The CTC stage is essential for the formation of distant metastases, and their continuing presence after radical prostatectomy has been shown to predict recurrent or latent disease. Despite their mechanistic and prognostic importance, due both to their scarcity and difficulties in their isolation, little is known about the characteristics that enable their production and survival. The aim of this study was to investigate the molecular mechanisms underlying the survival of CTC cells. A novel CTC cell line from the bloodstream of an orthotopic mouse model of castration-resistant prostate cancer was established and compared with the primary tumor using attachment assays, detachment culture, Western blot, flow cytometry and 2D gel electrophoresis. Decreased adhesiveness and expression of adhesion molecules E-cadherin, beta4-integrin and gamma-catenin, together with resistance to detachment and drug-induced apoptosis and upregulation of Bcl-2 were integral to the development of CTC and their survival. Using proteomic studies, we observed that the GRP94 glycoprotein was suppressed in CTC. GRP94 was also shown to be suppressed in a tissue microarray study of 79 prostate cancer patients, indicating its possible role in prostate cancer progression. Overall, this study suggests molecular alterations accounting for the release and survival of CTC, which may be used as drug targets for either anti-metastatic therapy or the suppression of latent disease. We also indicate the novel involvement of GRP94 suppression in prostate cancer metastasis.

Effects of moxibustion on expression of HSP70 protein and mRNA in stress-induced gastric ulcer of rats

AIM: To explore the mechanism of moxibustion on the acupoints of Foot-Yangming Meridian in protecting gastric mucosa by observing the effects of moxibustion pretreatment at Zusanli (ST36) and Liangmen (ST21) on HSP70 protein and mRNA expression in the stress-induced gastric ulcer of rats.

METHODS: Sixty Sprague Dawley rats were averagely randomized into blank group (A), model group (B), Zusanli and Liangmen-moxibustion group (C) and control group (D). The expression of HSP70 protein and mRNA of gastric mucosa were determined by immunohistochemistry and reverse transcriptase polymerase chain reaction (RT-PCR). The content of endothelin (ET) and prostaglandin E₂ (PGE₂) in gastric mucosa were detected by radioimmunoassay.

RESULTS: The ulcerative index (UI) was significantly different between group B and group A, C (P = 0.000, P = 0.001), as well as between group D and grop A, C (P = 0.001). Moxibustion on Zusanli and Liangmen relieved gastric mucosal injury obviously. The content of PGE₂ was markedly lower in group A than that in group B and D (P = 0.011, P = 0.028), but it was notably higher in group C (P = 0.020, P = 0.048). PGE₂ content was up-regulated after Moxibustion pretreatment. Meanwhile, Moxibustion lowered the content of ET (C vs B, P = 0.020), significantly. The expression of HSP70 protein and mRNA were increased in stress-induced gastric ulcer of rats (P = 0.039, P = 0.008), but Moxibustion pretreatment enhanced the up-regulated expression of HSP70 distinctly (C vs B, D: P = 0.003, P = 0.035; P = 0.000, P = 0.001 for protein and mRNA, respectively).

CONCLUSION: Moxibustion on Zusanli and Liangmen can protect gastric mucosa through inducing high expression of HSP70 protein and mRNA, with the relative specificity of the acupoints.