EXPRESSION OF 4 CEA FAMILY ANTIGENS (CEA, NCA, BGP AND CGM2) IN NORMAL AND CANCEROUS GASTRIC EPITHELIAL-CELLS - UP-REGULATION OF BGP AND CGM2 IN CARCINOMAS

Four human carcinoembryonic antigen (CEA) family members, CEA (CD66e), non-specific cross-reacting antigen (NCA, CD66c), biliary glycoprotei n (BGP, CD66a) and CEA gene-family member 2 (CGM2), are expressed in n ormal mucosal epithelia of the colon, Expression of BGP and CGM2 has r ecently been demonstrated to be down-regulated in colorectal adenocarc inomas, We have now investigated the expression of the 4 CEA family an tigens in gastric adenocarcinoma and carcinoma cell lines in compariso n with adjacent normal gastric mucosa, The transcripts of the CEA, NCA and BGP genes evaluated by reverse transcription-polymerase chain rea ction were detectable at various levels in all the gastric adenocarcin oma cell lines tested, while CGM2 mRNA was detectable in the cell line s of poorly differentiated but not of well-differentiated carcinomas, The levels of CEA mRNA in normal gastric mucosa were variable but most ly increased in adenocarcinomas, The sparse expression of NCA observed in the normal tissues was markedly up-regulated in the carcinomas, In contrast to previous findings on normal and cancerous colonic tissues , the transcripts of CGM2 were totally undetectable and those of BGP w ere recognized only marginally, if at all, in normal gastric mucosa, w hile both messages were detected at significant levels in most of the gastric adenocarcinomas, This was confirmed by in situ hybridization, Our findings indicate that expression of the CEA family antigens, part icularly that of BGP and CGM2, is differently regulated in epithelial cells of the colon and the stomach. (C) 1998 Wiley-Liss, Inc.