Alcohol, carcinoembryonic antigen processing and colorectal liver metastases

It is well established that alcohol consumption is related to the development of alcoholic liver disease. Additionally, it is appreciated that other major health issues are associated with alcohol abuse, including colorectal cancer (CRC) and its metastatic growth to the liver. Although a correlation exists between alcohol use and the development of diseases, the search continues for a better understanding of specific mechanisms. Concerning the role of alcohol in CRC liver metastases, recent research is aimed at characterizing the processing of carcinoembryonic antigen (CEA), a glycoprotein that is associated with and secreted by CRC cells. A positive correlation exists between serum CEA levels, liver metastasis, and alcohol consumption in CRC patients, although the mechanism is not understood. It is known that circulating CEA is processed primarily by the liver, first by nonparenchymal Kupffer cells (KCs) and secondarily, by hepatocytes via the asialoglycoprotein receptor (ASGPR). Since both KCs and hepatocytes are known to be significantly impacted by alcohol, it is hypothesized that alcohol-related effects to these liver cells will lead to altered CEA processing, including impaired asialo-CEA degradation, resulting in changes to the liver microenvironment and the metastatic potential of CRC cells. Also, it is predicted that CEA processing will affect cytokine production in the alcohol-injured liver, resulting in pro-metastatic changes such as enhanced adhesion molecule expression on the hepatic sinusoidal endothelium. This chapter examines the potential role that alcohol-induced liver cell impairments can have in the processing of CEA and associated mechanisms involved in CEA-related colorectal cancer liver metastasis.