[Determination and significance of C/EBP in hepatoma and various liver tissues]

C/EBP is a sequence-specific DNA-binding protein. In order to identify its distribution, localization and function in liver specimens from 18 normal adult, 5 neonates and 79 hepatocellular carcinoma patients (40 cases associated with surrounding nontumorous tissues), immunocytochemical studies (ABC method) were performed by using anti-C/EBP polypeptide antibodies 1103#, 425#. Northern blot using synthesized C/EBP cDNA probe in liver tissues of 3 normal adult, one neonate and 10 hepatocellular carcinoma tissues (8 cases were associated with surrounding nontumorous tissues) were also studied. The results of immunocytochemical staining showed that C/EBP was diffusely distributed in nuclei and cytoplasm of differentiated liver cells and very low or undetectable in liver cancer cells. The expression of C/EBP was in proportion to the degree of tumor cell differentiation and was much less than in the nontumorous surrounding tissues. C/EBP positive staining has also been found in the regenerating epithelial cells of bile ductules. Northern blot examination matched closely with the immunocytochemical examination. The results suggest that C/EBP may play an important role in establishing and maintaining the differentiation of liver cells and may exert an inhibiting effect against transformation of liver cells and proliferation of neoplastic tissue.