Expression of intercellular adhesion molecule 1 in human hepatocellular carcinoma

We investigated the expression of intercellular adhesion molecule 1 (ICAM-1) in ex vivo human hepatocellular carcinoma (HCC) cells and in vitro in eight liver cancer cell lines, including six HCC cell lines and two combined hepatocholangiocarcinoma (CHC) cell lines. Immunohistochemistry showed the expression of ICAM-1 on the HCC cell surface with honeycomblike appearance in most cases (96.2%). On the other hand, hepatocytes in noncancerous areas did not express ICAM-1, except those hepatocytes in the periportal and intra-acinar areas with inflammation. Immunohistochemical study on cultured cells revealed that four cultured HCC cell lines and one CHC cell line constitutively expressed ICAM-1 on the cell surface and in the cytoplasm. Flow cytometric analysis revealed that immunostain-positive cells expressed surface ICAM-1 with more than a 90% positive cell rate, and their expressions were upregulated by incubation of cells with inflammatory cytokines, such as interferon alfa, interferon gamma, tumor necrosis factor-alpha, and interleukin 1 beta. Soluble ICAM-1 was detected in supernatants of cell lines expressing cell surface ICAM-1 expression, and was increased in amounts 2- to 20-fold by inflammatory cytokines. These findings suggest that liver cancer cells in ex vivo may express not only surface but also a soluble form of ICAM-1, differently from normal hepatocytes, and that both expressions are upregulated by inflammatory cytokines.