Estrogen regulation of growth and specific protein synthesis in human breast cancer cells in tissue culture.

Abstract

Taking advantage of the fact that estrogens can stimulate proliferation of antiestrogen-inhibited MCF-7 cells has enabled us to study molecular events involved in steroid-mediated growth of tumor cells, using a breast cancer cell line which otherwise is affected very little in its growth by estrogens. Under these growth conditions, estradiol stimulates DNA polymerase activity in a manner analogous with reported estrogen effects on enzyme activity in normal target tissues. We also observed dissociation of estrogen effects on cell growth and PgR stimulation, indicating that PgR induction and estrogen-mediated cell division may involve separate control mechanisms. The relative rate of synthesis of the 24,000 molecular weight protein is also increased under these conditions of estrogen-stimulated cell growth. Since increased synthesis of the 24,000 molecular weigh protein was determined not to be a reflection of different stages of cell growth, we suggest that this protein is regulated specifically by estrogens and that it may be a marker of estrogen stimulated growth of human breast tumor cells.