DIFFERENTIAL EXPRESSION OF CARCINOEMBRYONIC ANTIGEN AND NONSPECIFIC CROSSREACTING ANTIGEN GENES IN HUMAN COLON ADENOCARCINOMAS AND NORMAL COLON MUCOSA

Abstract

The level of mRNA for carcinoembryonic antigen (CEA) and nonspecific crossreacting antigen (NCA) in human colon adenocarcinomas and normal colon mucosa was analyzed by Northern blot hybridization using as probes 32P-labeled CEA cDNA and synthetic oligodeoxyribonucleotides specific to CEA and NCA mRNA sequences. The major 3.5-kb mRNA and a minor 4.2-kb mRNA are shown to be CEA-specific and expressed in both tissues, albeit at slightly different degrees, suggesting that the expression of CEA is regulated posttranscriptionally. Another minor mRNA of 2.9 kb is NCA-specific and expressed predominantly in cancerous tissues, suggesting its usefulness as a marker for colon cancer.