Hormonal regulation in two rat mammary cancer cell lines: glucocorticoid and androgen receptors.

We have studied the hormonal control of two continuous cell lines derived from rat-mammary tumors induced by two different carcinogens (dimethylbenzanthracene and N-nitrosomethylurea). The steroid receptors were assayed using charcoal or hydroxyapatite and the effect of different hormones on cell growth was evaluated by measuring total DNA and following the growth of transplanted cells in nude mice. Similar results were found for the two cell lines; they were unresponsive to estrogen since they did not contain appreciable amounts of estradiol receptor. Conversely, these two cell lines contained high concentrations of androgen and glucocorticoid receptors, which were both transferable to the nucleus. While dexamethasone stimulated, directly or indirectly, the growth of RBA and NMU cells, the effect of androgens on cell growth is still questioned. These two cell lines offer a potential model to study the mechanism of action of androgens and glucocorticoids in mammary cancer.