Expression and growth‐promoting effect of adult t‐cell leukemia‐derived factor a human thioredoxin homologue in hepatocellular carcinoma

Abstract

Adult T‐cell leukemia‐derived factor (ADF), originally defined as an interleukin‐2 receptor inducer, is a human thioredoxin homologue. ADF is detected in many malignant tissues and has a growth‐promoting effect on transformed cells. In this study, ADF expression was examined immunohistochemically in human liver cell lines and liver tissues, and its growth‐promoting effect was tested on human hepatoma cells. On three liver cell lines—PLC/PRF/5, HepG2, and Chang liver cells—ADF stained positively and also was detected by immunoblotting. ADF had strong staining in the fetal liver (n = 8), although it was faint in the normal adult liver (n = 6). In hepatocellular carcinoma (n = 25), ADF expression generally was enhanced and was very strong in 52% (13 of 25) of the cases, although it was moderate in cases of chronic hepatitis or cirrhosis. ADF augmented the growth of PLC/PRF/5 cells and showed an additive effect with epidermal growth factor. These results indicate possible involvement of ADF in cell activation and growth of hepatocytes, as is the case with lymphocytes. Copyright © 1992 American Cancer Society