[Suppression of alpha-fetoprotein gene expression in somatic hybrids of AFP-positive and AFP-negative clones of rat hepatoma].

The presented study is devoted to investigation of molecular mechanisms regulating alpha-fetoprotein (AFP) gene expression at transcriptional level. The study was carried out on AFP-positive and AFP-negative clones of rat hepatoma McA-RH 7777 that also differ in hepatocyte nuclear factors (HNF) 1 and 4 transcription levels. To examine a hypothesis of existence in AFP-non-producing clones a transcriptional factor that downregulates this gene expression, we have obtained somatic hybrids of AFP-positive and AFP-negative clones. In the obtained hybrids AFP gene expression is decreased while expression of HNF1, one of the main AFP promoter activators, is maintained. These data indicate an existence of a repressor in AFP-negative clones that determines AFP gene downregulation regardless of the HNF1 expression level.