Stable transfection of retinoblastoma gene promotes contact inhibition of cell growth and hepatocyte nuclear factor-1-mediated transcription in human hepatoma cells.

The retinoblastoma (Rb) gene is a key factor involved in cell cycle regulation. In the present study, alterations in cell growth and expression of the alpha-fetoprotein and albumin genes by the stable transfection of the Rb gene were analyzed in HuH-7 human hepatoma cells. Cell growth was almost similar in the Rb gene-transfected and nontransfected cells at the sparse cell density. However, under a confluent condition, contact inhibition of cell growth was stimulated by the Rb gene transfection. By Northern blotting, the levels of the alpha-fetoprotein and albumin mRNA as well as the transcript of hepatocyte nuclear factor-1 (HNF-1), a liver-specific transcriptional factor regulating both genes, were apparently elevated in the Rb gene-transfected cells, compared with the nontransfected cells. These results suggest that the Rb gene transduction promotes contact growth inhibition in conjunction with the enhanced HNF-1-mediated liver-specific gene transcription in human hepatoma cells.