Expression and bioactivity identification of soluble MG7 scFv

Construction and characterization of a novel fusion protein MG7-scFv/SEB against gastric cancer

Antibody-targeted superantigen has been developed into a new strategy to treat many malignant tumors. In this study, for specific targeting to gastric cancer cell, superantigen SEB (Staphylococcal Enterotoxin B) was genetically fused to the single-chain variable fragment of gastric carcinoma-associated antibody MG7(MG7-scFv) that recognizes the MG7 antigen frequently expressed in gastric cancer cell. The recombinant MG7-scFv/SEB fusion proteins are expressed in E. coli as inclusion bodies, and the purified MG7-scFv/SEB retains high binding affinity with gastric cancer cell SGC-7901 (positive MG7 antigen expression). When incubated with effector cell-peripheral blood mononuclear cells (PBMCs), MG7-scFv/SEB could effectively inhibit the proliferation and induce apoptosis of SGC-7901. After being treated with MG7-scFv/SEB, PBMCs remarkably increased the production of Th1 cytokines (IFN-gamma, IL-2), and slightly increased the production of Th2 cytokines (IL-4, IL-10) in vitro. It was observed that gastric-tumor-bearing rats administrated with MG7-scFv/SEB showed more inflammatory cell infiltration, more significant tumor inhibition, and longer survival time than those of rats treated with SEB or NS (Normal Saline). The data indicated that MG7-scFv/SEB fusion protein could specifically target gastric cancer cell, enhance the activity of T cells and induce tumor cell apoptosis to exert the antitumor effect on gastric cancer.

Expression and prognostic value of MG7-Ag in patients with surgically resectable esophageal squamous cell carcinoma

PURPOSE

MG7-Ag is a human gastric-carcinoma-associated antigen. The expression of MG7-Ag was found to increase gradually with the development and progression of gastric cancer. Moreover, a poorer prognosis was found in MG7-Ag positive gastric-carcinoma patients than in MG7-Ag negative patients. However, neither MG7-Ag expression nor its clinical significance has been previously examined in squamous cell carcinoma (SCC) of the esophagus. In this study, we examined the expression of MG7-Ag in esophageal squamous cell carcinomas to assess its value as a prognostic indicator.

METHODS

The expression of MG7-Ag was detected in 112 cases of esophageal squamous cell carcinoma (SCC) by immunohistochemical analysis. The relation of MG7-Ag staining with various clinicopathological features was statistically analyzed.

RESULTS

The staining of MG7-Ag was detected in SCC, while not in normal epithelial cells. In esophageal SCC, MG7-Ag was found significantly correlated with depth of invasion (P = .012), in T4, T3 carcinomas but not in T2, T1 carcinomas, lymph node metastases (P = .029), pathological stage (P = .005). Consistently, the survival rate tended to be statistically lower in patients with MG7-Ag positive SCCs than in MG7-Ag negative SCCs (P = .005). However, no significant difference was observed between MG7-expression and patient age, sex, tumor location, differentiation, distant metastasis, and lymphatic invasion.

CONCLUSION

MG7-Ag might play a positive role in the process of carcinogenesis and progression of esophageal SCC, and it could be considered as one valuable prognostic indicator in esophageal SCC.

Gene therapy for gastric cancer: A review

Gastric cancer is common in China, and its early diagnosis and treatment are difficult. In recent years great progress has been achieved in gene therapy, and a wide array of gene therapy systems for gastric cancer has been investigated. The present article deals with the general principles of gene therapy and then focuses on how these principles may be applied to gastric cancer.

Effect of expression of interferon-g gene in inhibition of growth of colon cancer cell

AIM: To investigate the effect of expression of interferon-γ(IFN-γ) in tumor cell and its inhibitory effect on the growth of tumor cell.

METHODS: pcDNA3-IFN-γ vector containing IFN- γ gene was constructed and transfected into LOVO, SW620, HCT116BG and Hela cell lines by lipofectamine, respectively. The expression of IFN-γ, CEA and HLA-DR in transfected cells were tested. Both the number of apoptosis of and the proportion of cell cycles of tumor cells were measured to investigate the anti-tumor effect of IFN-γ gene therapy.

RESULTS: LOVO and HCT116BG transfected cell lines had high expression of CEA, the average level of CEA was significantly increased from 26.02±6.76 to 38.85±7.07 mg/L (P < 0.05). However, there was no detectable increase in the supernatants of Hela, SW620 cell lines that naturally expressed little of CEA. Flow cytometry analysis showed that HLA-DR expression rate (11.67±7.20) was significantly higher than that prior gene transfection (3.91±3.61) (P < 0.01), and the IFN-γ gene transfer effectively induced the apoptosis of tumor cells, the proportion of DNA synthesis phase was deceased gradually after IFN-γ gene transfer, which indicated that the synthesis of DNA and growth of tumor cells were repressed.

CONCLUSION: IFN-γ gene therapy enhanced the expression of antigens on cell surface and thus induced powerful antitumor immunity. Repressing of synthesis of DNA, inducing the apoptosis of tumor cells and inhibiting the proliferation of tumor cells might be anti-tumor mechanisms of IFN-γ.