Differential effects of steroid hormones on parameters of cell growth.

Steroid hormones affect the growth of many tumor cells both in vivo and in vitro. Growth of cells in vitro can be studied as either anchorage dependent (monolayer culture) or anchorage independent (suspension culture), and in each case, steroid hormones can alter log-phase proliferation rate, saturation density, or cell morphology. Results presented here demonstrate that different steroid hormones can have different effects on each of these parameters in breast cancer cells. In androgen-responsive cells, glucocorticoid and androgen both stimulated fibroblastic morphology and saturation density in monolayer and growth in suspension, but glucocorticoid inhibited log-phase proliferation rate while androgen stimulated it. By transfection experiments, it has been possible to separate the androgen-regulated stimulation of cell proliferation from the androgen-regulated cell morphology changes indicating that the two parameters are not totally interdependent. The same separation, however, was not achieved for glucocorticoid regulation. Further separation of hormone effects was achieved also during the natural course of progression to steroid autonomy. In particular, the androgen and glucocorticoid stimulations of growth in suspension were separated. The experiments described here carry important messages for the design and interpretation of any experiment aimed at elucidating molecular events involved in steroid-mediated cell growth in culture.