EXPRESSION OF CD44 IN HUMAN HEPATOCELLULAR-CARCINOMA CELL-LINES

CD44 is a glycosylated cell surface adhesion molecule expressed on a d iverse range of cells and has several variant forms, some of which are involved in metastasis of cancer cells. Because little is known about CD44 in human hepatocellular carcinoma (HCC), we investigated its exp ression in tissue specimens from primary lesions (12 cases), in smear specimens from peritoneal effusions (2 cases), and in cell lines (HCC cell Lines, KIM-1, KYN-1, KYN-2, KYN-3, HAK-1A, and HAK-1B; combined h epatocholangiocarcinoma cell lines, KMCH-1 KMCH-2; and bile duct carci noma cell lines, KMC-1 and KMBC). Immunohistochemical studies using mo noclonal antibody recognizing epitope Group 1 of human CD44 molecule s howed that HCC cells in all tissue specimens, including the original t umors of one smear specimen and HAK-1A, were negative for CD44; wherea s, HCC cells in two-smear Specimens, KIM-1, KYN-2, KYN-3, HAK-1A, HAK- 1B, KMCH-1, KMC-1, and KMBC showed positive reactions on the cell memb rane. Immunostain-positive cell lines showed a positive cell rate of 5 1.9% to 99.8% by flow cytometric analysis. Western blotting detected C D44 protein of hemopoietic type in KIM-1, KYN-3, HAK-1A, and HAK-B and epithelial type in KMC-1 and KMBC. Southern blotting of complementary DNA amplified after reverse transcriptase-polymerase chain reaction ( RT-PCR) detected hemopoietic type and some variant forms with longer i nsertion in all cell lines but KMCH-2, whereas hemopoietic type and va riants with minor insertion were only detectable in tissue specimens. These findings suggest that HCC cells in ascites and in culture often express CD44, but those in tissue do not at protein level.