Effects of T-Synthase activity on the expressing of Tn/STn and T/ST antigens in gastric carcinoma tissues

Abstract

Objective To explore the effects of T-Synthase activity on the expression of tumor-associated carbohydrate antigens(TACAs),Tn,STn,T and ST in gastric carcinoma tissues.Methods The tumor cells were separated from gastric carcinoma tissues of different TNM stages by density gradient centrifugation,and the counts of Tn+ and Tn-cells were further tested by flow cytometry (FCM).The Tn+ and Tn+ cells were selected from cultured gastric tumor cells by immune magnetic bead.In these cells the expression of Tn,STn,T and ST antigen in membrane extracts,and the T-Synthase mRNA were detected by Western blot and RT-PCR respectively,then using GalNAcα1-O-phenyl as acceptor for UDP-[H3]-Gal,T-Synthase activity in cell extracts were determined by radioactivity.The relationship between Tn antigen and T-Synthase activity were analyzed.Results 39.66%patients' gastric tumor cells are only Tn+ cells,29.31%patients' cells are mixture of Tn+ and Tn-Ⅰ cells,31.03%patients' cells are only Tn-cells.Tn and STn antigen co-expressed in Tn+ cells,have no T and ST antigen.ST antigen expressed in both of Tn-Ⅰ and Tn-cells,and T antigen expressed in proportion of Tn-Ⅰ cells.No difference of T-Synthase mRNA was detected between Tn+,Tn-Ⅰ and Tn-cells,but T-Synthase activity in Tn+ cell extracts was much lower than that in Tn-cell.Conclusion The expression of Tn,STn,T and ST antigen in gastric carcinoma tissues of different TNM stages is different.Tn antigen expression in tumor cells may be caused by the decrease of T-Synthase activity. Key words: Gastric carcinoma; T-Synthase; Tn antigen; T antigen