Effects of sodium butyrate and 5-bromo-2'-deoxyuridine on the synthesis of human chorionic gonadotropin in human placental cells transformed by tsA mutants of simian virus 40.

The synthesis of hCG and its subunits was studied in simian virus 40 (SV40) tsA mutant-transformed human first trimester and term placental cells at 33 C (the temperature at which the cells have the transformed phenotype) and 40 C (the temperature at which the temperature-sensitive tsA transformants regain their nontransformed phenotype). In the presence of sodium butyrate at 33 C, synthesis of both hCG and hCG alpha was greatly induced in the tsA transformants. at 40 C, hCG synthesis was induced by sodium butyrate, although to a lesser extent than at 33 C. Yet, hCG alpha synthesis was inhibited by sodium butyrate at 40 C. In the presence of 5-bromo-2'-deoxyuridine (BrdUrd) at 33 C, hCG synthesis was not affected in the transformed first trimester placental cells and was induced in the transformed term placental cells. In the presence of BrdUrd at 40 C, hCG synthesis was induced in both forms of placental cells. The synthesis of the free hCG alpha-subunit appeared to be controlled differently. At 33 C, hCG alpha synthesis was also induced by BrdUrd. At 40 C, however, hCG alpha synthesis was inhibited by BrdUrd. hCG synthesis was induced and hCG alpha synthesis was inhibited by sodium butyrate and BrdUrd in the tsA-transformed placental cells grown at 40 C. Whereas the synthesis of both hCG and hCG alpha in choriocarcinoma cells has been reported to be inhibited by both sodium butyrate and BrdUrd. Our data indicate that the effects of sodium butyrate and BrdUrd on the production of hCG, but not hCG alpha, were different in the SV40 tsA-transformed placental cells and choriocarcinoma cells.