Downregulation of Src Family Kinase Activity Using PP2 Inhibitor Has No Effect on the Elongation of PragminTransfected Adenocarcinoma AGS cells

Introduction: Pragmin is the first mammalian protein that contains a functional the GluProIleTyrAla (EPIYA) motif. Pragmin is tyrosinephosphorylated at EPIYA motif by Src family kinases (SFKs), Cterminal Src kinase (CSK), and in response to epidermal growth factor (EGF) stimulation. Pragmin can induce some morphological changes in transfected cells characterized by cell elongation, which can be construed as an invasive phenotype contributing to tumor invasion and metastasis. This study was established to investigate Src role as a key regulator of cell motility to induce elongated morphology of cells in Pragmin transfected AGS cells, a human gastric adenocarcinoma cell line, by using PP2, a specific inhibitor of Src family protein kinase. Methods: Firstly, AGS cells were transfected with Pragmin and Pragmin mutant (Y391F) using lipofectamine 2000 reagent and then we treated the cells by PP2. Finally, we evaluated cellmorphological changes in the presence or the absence of PP2 by using light microscopy and the results were analyzed. Results: Our results showed in AGS cells that were transiently transfected by Pragmin in the presence of PP2 (where Src tyrosine kinase activity was inhibited), the number of elongated cells did not change compared to elongated cell numbers of Pragmin transfected cells in the absence of PP2. Conclusion: Our findings suggest that in spite of the importance of Src tyrosine kinase activity to regulate the cell motility, the cellmorphological changes of Pragmintransfected AGS cells is independent of Src activity. It seems that other mechanism(s) to be involved in this process.