Hydrocortisone stimulation of human mammary epithelial cells.

Rapid proliferation of mammary epithelial cells derived from biopsy specimens of human fibroadenomas was observed when medium was supplemented with ten percent fetal bovine serum and hydrocortisone (5 microgram per ml-1). Hydrocortisone in combination with FBS also led to a 2.5-fold increase in cell cluster attachment and subsequent colony formation. A similar effect was not observed with human serum. In contrast to fibroblast cell systems, insulin did not significantly alter cell growth. The results show that a mitogenic response to glucocorticoids by mammary epithelium may depend on the presence of factors in sera.