[Effect of cyclic AMP and adenosine on hCG transcription by trophoblast cells]

It is well established that cAMP stimulates secretion of both alpha and beta subunits of hCG by trophoblasts. However, the molecular mechanism behind this phenomenon, especially that of beta subunit stimulation is still obscure. Moreover, while adenosine is known to play a pivotal role in the message transduction system of various cells, its effect on trophoblasts is not known. We therefore tried to answer these questions and found that cAMP stimulates hCG beta secretion by increasing transcription of its mRNA. However, no discrete cAMP responsive element like that seen in the hCG alpha gene seemed to be present in hCG beta transcriptional regulatory elements. It was assumed that hCG beta transcription is augmented indirectly by numerous trans acting elements which respond to cAMP. We have also shown that adenosine is a potent stimulator of hCG production. Its effect was synergistic with cAMP. It was therefore assumed that adenosine and cAMP are likely to act through different pathways.