Androgen regulates MMTV RNA in the short-term in S115 mouse mammary tumour cells.

This report demonstrates that androgens as well as glucocorticoids can regulate MMTV RNA production in the short term. In S115 mouse mammary tumour cells, MMTV RNA accumulation is regulated within hours by androgen, at a time before any increase in DNA synthesis can be detected, thus providing a marker of an early postreceptor molecular event in steroid action on these cells. Androgen acts via its own receptor and not by cross-binding to the glucocorticoid receptor. The effects are at transcription and not just on stabilisation of RNA because they are blocked by actinomycin D. However, the androgen action shows some partial dependence on simultaneous protein synthesis since cycloheximide is inhibitory. The androgen regulation of MMTV RNA is compared and contrasted with that by glucocorticoids in these cells.