[Human breast cancer cells under serum-free culture. Its hormone-dependency and application to the primary culture].

Assessment of hormone-dependency of breast cancer cells in human to estradiol (E2) and progesterone (Pg) has been made by making serum-free culture of the cells, and primary culture of breast cancer cells is made by this method. The results are as follows: 1. E2 promotes proliferation of estrogen receptor (ER)-positive cells in low concentrations but rather inhibits it in high concentrations. This inhibitory effect is also observed in ER-negative cells. If the mode of this inhibitory effect is compared with the cellular dynamics of Tamoxifen (TAM) which binds predominantly to ER, the cellular dynamics of E2 in high concentrations resembles that of TAM, from which some influence being exerted on the binding site of TAM by high concentrations of E2 is presumed. 2. At binding of E2 to ER, S phase fraction increases significantly for 24 hours of culture if analyzed from the cellular dynamics, proving that the binding occurs comparatively in a short period. 3. Inhibition of cellular proliferation by PgR depends on the concentration. PgR is not induced with only E2, and interference of other factors is suggested in the induction. 4. Proliferation of the initially cultured cells is promoted by E2 although ER is present or not.