Thyroid hormone effect on α-fetoprotein and albumin coordinate expression by a human hepatoma cell line

Abstract The action of triiodothyronine on the production of α-fetoprotein and albumin in serum-free cultures of Hep G2 human hepatoma cells was examined. Our data showed that a marked inhibition (up to 8-fold) of α-fetoprotein secretion and an increase in albumin (up to 4-fold) are produced by 10 −8 M triiodothyronine. These effects were slow in their onset and for completion required 20–25 days of treatment with the hormone. However, an exposure of the cells to triiodothyronine for only the first 4 h was sufficient to affect, in a similar way, the secretion of α-fetoprotein and albumin when measured 15 days after treatment. The secretion of the two proteins parallels their intracellular levels. The decrease in α-fetoprotein production can be explained by a reduction of the RNA coding for the protein. The same is essentially true also for albumin increased secretion and related mRNA expression.