| As a common malignant carcinoma in Gastroenterology system, the treatment of gastric cancer mainly depends on gastrectomy and chemotheraphy. Early diagnosis is important in raising survival rate of patients. Because of complicated relations presented in gastric cancer, the study of tumor marker and gene therapy are difficult remain. Previous studies, have shown that calcium- binding protein S100A2 gene and Pancreatic derived factor gene FAM3B expressed differentially in gastric epithelia and gastric cancer epithelia. Up to date, the roles they play in gastric cancer are not completely known. In the present study, we investigated their effects on the cell line of gastric cancer BGC823.Objective: To study the effects of calcium-binding protein S100A2 gene and Pancreatic-derived factor gene FAM3B on gastric cancer cell line BGC823.Methods:1 .Using RT-PCR,Western blot and immunocytochemistry, to detect the expression of S100A2 and FAM3B in gastric cell lines: GES-1,SGC7901,MGC803 and BGC823.2.Using RT-PCR, to amplify the whole sl00a2 and FAM3B gene from a normal tissue, and construct eukaryotic expression plasmid by gene recombinant technique. After transfected recombinant plasmid into gastric cancer cell line BGC823, to determine their sublocation with laser confocal microscopy.3. To obtain cell subclones which stably expressed S100A2 and FAM3B genes respectively. Through analysis of their cellular morphology, proliferation index, cell cycle, invasion and apoptosis, to elucidate their biological functions on gastric cancer cell line BGC823.Results:1.The expression of mRNA and protein of S100A2 gene was depressed in gastric cancer cell lines; However, the expression of mRNA and protein of FAM3B have no obvious difference among cell lines, immunocytochemistry indicated that the expression of FAM3B gene was higher in GES-1 than BGC823 and SGC7901.2. The Eukaryotic expression vector of p EGFP-N2-FAM3B and p EGFP-N2-S100A2 was successfully constructed. After transfection, their sublocation can be observed marked by green fluorescence protein (GFP) under the fluorescence microscope. S100A2 located in cytoplasm near nuclear membrane and FAM3B located in cellular nucleus.3.Through screen with G418 screening, stable transfected cell lines were obtained. The morphology has no obvious difference between transfected cell and BGC823 with HE dyeing; the proportion of G0/G1 cells increased in S100A2 and FAM3B transfected cells than BGC823, the proliferation ratio is declined. The proliferation speed of transfected groups were depressed apparently; The invision ability of transfected S100A2 group cell were increased compared with empty vector group cell; With the same treatment of Tax , the fragment of 89KDa protein were increased in S100A2 and FAM3B group.Conclusion:1,The expression of S100A2 were depressed in gastric cancer cell lines SGC7901,MGC803,BGC823, indicated that S100A2 gene maybe a tumor suppress gene. After transfected into BGC823 cells,the gene expressed in cytoplasm ,and the grow relative slowly and inducce apoptosis but can enhance the invision ability,so we proposed that S100A2 involved in cell growth,motion and apoptosis with different mechanisms.2,The mRNA expression of FAM3B were low in all 4 cell lines, but from cytoinmunity chemistry, the FAM3B were found in GES-1 and BGC823 lines, has no expression in SGC7901 at all. Because of expression in cytoplasm in GES-lbut nucleus in BGC823, inducing BGC823 to grow slowly and involving apoptosis after be transfected, we concluded that gene FAM3B maybe a tumor inhibitor in gastric cancer.
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