THE DNA-BINDING ACTIVITY OF THE LIVER TRANSCRIPTION FACTORS LFB1 (HNF1) AND HNF4 VARIES COORDINATELY IN RAT HEPATOCELLULAR-CARCINOMA

As renal cell carcinomas are characterized by the disappearance of the transcription factor LFB1, which is known to be primarily involved in gene regulation in the liver, we have measured the presence of LFB1 i n rat hepatocellular carcinomas induced by diethylnitrosamine. The lev el of LFB1 binding activity in adenoid-cystic as well as trabecular tu mours shows some variation and may either be lower or higher than in t he non-tumorous tissue. The amount of LFB1 binding activity correlates with the binding activity of HNF4, a transcription factor reported to stimulate LFB1 expression. As the levels of LFB1 and HNF4 binding act ivity differ extensively in various hepatocellular carcinomas, it is u nlikely that these transcription factors play a general role in hepato carcinogenesis. This is in contrast to renal carcinogenesis where a dr amatic loss of LFB1 is a consistent feature.