Carcinoembryonic antigen gene and carcinoembryonic antigen expression in the liver metastasis of colorectal carcinoma

The presence of the carcinoembryonic antigen (CEA) gene and CEA expression in the liver was tested to identify their possible roles in the liver metas tasis of colorectal carcinoma. The CEA gene in the liver was identified by amplifying the CEA-specific N-terminal domain exon with digoxigenin-dUTP la beling in 16 colorectal carcinomas with liver metastases. Next, CEA express ion was tested by immunostaining using the anti-CEA monoclonal antibody (T8 4.66, ATCC). Liver tissues from 13 stomach cancer patients and 12 colorecta l cancer patients without liver metastasis were also tested as control grou ps. Three grades (<25%, 25-50%, and 50%less than or equal to) were given ac cording to the proportion of positive cells. The CEA gene was amplified in the metastatic tumor cells of the liver (2.6 +/- 0.2, mean grade +/- SEM) a nd their surrounding hepatocytes (1.5 +/- 0.2) in all cases. CEA expression was found in all metastatic tumor cells and 14 cases of the surrounding he patocytes, Among the control groups, the CEA gene of the hepatocytes was fo und in 9 cases each of the colorectal and the stomach cancers that did not exhibit CEA expression, The level of serum CEA was related with the numbers and volume of liver metastases, but not with CEA expression in tumor cells and surrounding hepatocytes. The CEA gene in the metastatic tumor cells, n ot in the hepatocytes, was closely associated with CEA expression in the su rrounding hepatocytes (p<0.01). Although the precise mechanism of CEA gene regulation in hepatocytes remains to be proven, the CEA gene in the metasta tic tumor of the liver seems to affect CEA expression in the surrounding he patocytes facilitating liver metastasis in colorectal carcinoma.