Overexpression of N-terminal amino acids of p55γregulatory subunit of PI3K inhibits cell adhesion of human gastric carcinoma MGC803 cells / 中国病理生理杂志

ABSTRACT

AIM:To investigate the effect of the N-terminal 24-amino acid (N24) overexpression in p55γre-gulatory subunit of phosphatidylinositiol 3-kinase ( PI3K) on the cell adhesion of human gastric carcinoma cell MGC 803. METHODS:MGC803 cells, which stably expressed GFP-N24 fusion protein and GFP alone , were generated by transfec-tion with pEGFPN-24 plasmid and control plasmid pEGFP-C1, respectively.The morphological change of the cells was ob-served under inverted microscope .The expression of GFP-N24 fusion protein was detected by Western blot .The adhesion of the cells was determined by cell adhesion assay .The effects of GFP-N24 fusion protein on the expression of E-cadherin andβ-catenin were analyzed by Western blot .The expression and secretion of matrix metalloproteinase 9 (MMP9) and u-rokinase-type plasminogen activator ( uPA ) in the MGC803 cells were detected by gelatin zymography .RESULTS:MGC803/GFP-N24 cell line steadily expressed GFP-N24 fusion protein and MGC803/GFP cell line steadily expressing GFP were successfully established , but the expression of fusion protein GFP-N24 was lower than that of the control protein GFP.The morphological changes of the transfected cells from paving stone to fibroblast cell form after gene transfection , and the cytoplasm secretory granules were increased significantly .The cell adhesion to fibronectin and collagen decreased after GFP-N24 transfection .GFP-N24 fusion protein increased the expression of cell adhesion molecule E-cadherin and de-creased the wnt signal pathway molecule β-catenin in the MGC803 cells.However, it did not affect the expression and se-cretion of tumor metastasis-related proteins MMP9 and uPA.CONCLUSION:Overexpression of N24p55γinhibits cell ad-hesion by influencing the expression of E-cadherin and β-catenin in the MGC803 cells.