Short- and long-term estrogen deprivation of T47D human breast cancer cells in culture

The effects of short- and long-term estrogen deprivation on T47D human breast cancer cells was studied. Cells were routinely grown in an estrogenized environment in media containing fetal bovine serum with phenol red indicator. Cells were estrogen deprived (grown in media containing dextran-coated charcoal-stripped fetal bovine serum without phenol red) for either 10 days or at least 8 months, and effects on genotype, receptor content, and cell growth responsiveness were studied. Cells grown in an estrogenized environment are hypertetraploid, whereas long-term estrogen-deprived cells have become hyperdiploid. Short-term estrogen-deprived cells exhibit a decreased growth rate and progesterone receptor (PgR) content, while estrogen receptor (ER) content is not significantly altered. ER mRNA levels are significantly decreased in these cells. Incubation of these cells with estradiol (10^-10 M) for 6 days causes a 5-fold stimulation in cell growth and this stimulation can be inhibited by the antiestrogens 4-hydroxytamoxifen (4-OHT), ICI 164,384, and RU 39411. Cells cultured under long-term estrogen deprivation exhibited an increased growth rate and were refractory to the effects of estradiol and of 4-OHT on cell growth. These cells were ER negative with low levels of PgR; however, one clone of this line was found to be ER and PgR negative. No mRNA for the ER was detected in this line or its clone. With these cell lines it is possible to study the biological characteristics necessary for the outgrowth of a receptor negative, hormone nonresponsive cell population from a receptor positive, hormone-responsive population grown in a estrogen-free environment.