Effect Of Exogenous FHIT Gene On Proliferation And Chemosensitivity Of Gastric Cancer Cells

[Background and Objective]Gastric carcinoma is one of the most common malignant tumors of mankind, and it has high incidence and death rate in China so it's a serious threaten to human health. Nowadays, chemotherapy is one of the most therapeutics to gastric carcinoma, but it hasn't gotten ideal effect, one of the main reasons that hinder therapeutic efficacy is the drug resistance of tumor cells. Accordingly, how to raise the curative effect of drugs is a warm spot to study. FHIT (fragile histidine triad) gene is one of the anti-oncogenes that have been discovered recently and also is the first anti-oncogene that connects fragile site with tumors. A great deal of researches has indicated that FHIT abnormality maybe relevant to the carcinogenesis and development of gastric carcinoma. Majority of chemotherapeutics obtain their anti-cancer effect by inducing the tumor cells apoptosis. Apoptosis regulation can influence expression of some anti-oncogenes and some tumor cells' chemosensitivity to some drugs, but the defect of the apoptosis mechanism play an important role in forming drug resistant. Gene therapy is a hot spot of oncotherapy at present, chemotherapy connecting with gene therapy has becoming one of new combined therapies of tumor. Some findings have indicated that FHIT gene could enhance apoptosis and also change the chemosensitivity of some tumor cells, but little analogous reports about gastric carcinoma appeared.In the present study, the effect of FHIT gene on proliferation and chemosensitivity of human gastric carcinoma cells were observed by transfecting FHIT gene into gastric carcinoma cells MGC-803 which was absent of FHIT expression through the mediator liposome.[ Methods]Plasmids that extracted by alkaline lysis were identified by sequencing.By the method of liposome transfection,plasmids pRC/CMV-FHIT and pRC/CMV were transfected into gastric cancer cell line MGC-803 which was absent of FHIT gene expression, after screening the transfected cells with G418 and identificating the FHIT protein with Western blot, the effect of FHIT on proliferation of gastric cancer cells was observed by colony formation test and growth curves, the survival rate and IC₅₀ of gastric cancer cells to drugs were obtained by MTT assays ,through which the effect of FHIT on chemosensitivity of gastric cancer cells was investigated.[Results](1) The sequencing of the extracted plasmid was at equal pace with the gene bank, and the concentration and the purity of plasmids were fitted for test requirement.(2) The gastric cancer cells transfected with FHIT gene expressed FHIT protein stably.(3) Compared with the parental cells and negative control cells, the reproductive activity decreased.The colony formation rate of MGC-803-FHIT and MGC-803 and MGC-803-vector were ( 19.67±3.16) % and (35.00±3.16)% and ( 29.50±4.76) % respectively, and the apoptosis rate of three groups were (19.59±2.90) % and (3.38±1.29) % and (4.41±0.94) % respectively . All these differences between MGC-803-FHIT cells and the two control groups of gastric cancer cells have statistical significance.(4) Compared with the parental cells and negative control cells, the survival rate of MGC-803-FHIT cells for DDP decreased but that of 5-FU increased.The IC₅₀ of MGC-803-FHIT cells for DDP decreased from (4.17±0.07) mg/L and (4.06±0.19) mg/L to (2.09±0.50) mg/L ,while that for 5-FU increased from ( 0.60±0.08) mg/L and (0.57±0.05) mg/L to (1.78±0.39) mg/L ,and all these differences between MGC-803-FHIT cells and the two control groups have statistical significance.[ Conclusion]Exogenous fragile histidine triad (FHIT) gene suppressed proliferation and promoted apoptosis of gastric cancer cell line MGC-803.The influence of two drugs on chemosensitivity of three groups of gastric cancer cells was different. Our studies indicated that FHIT gene was capable of enhancing the sensitivity of MGC-803 cells to DDP and lowering that to 5-FU. All these findings suggest that using FHIT gene combined with anticancer drugs maybe improve or reduce the effectiveness of chemotherapy and in turn offer guidance for clinical medication.