Eckert R L, Katzenellenbogen B S
J Recept Res. 1983;3(5):599-621. doi: 10.3109/10799898309041950.
Progesterone receptor levels in MCF-7 human breast cancer cells increase as a specific response to estrogen and to some nonsteroidal antiestrogens. In the present study we demonstrate that the type and quantity of serum present during culture of these cells modifies the level of progestin binding activity, but not the level of estradiol binding activity. MCF-7 cells maintained in media supplemented with 5% charcoal-dextran treated calf serum (CDCS) contain 0.3 - 0.4 pmol of cytosol progesterone receptor (PRc) per mg DNA. When cells previously maintained in 5% CDCS-media are shifted to media containing 5% charcoal-dextran treated fetal calf serum (CDFCS), the level of progestin binding increases after day 16, and stabilizes at 2 - 3 pmol/mg DNA at days 30 to 40. Shifting these cells back to 5% CDCS-media, reduces PRc to 0.2 - 0.4 pmol/mg DNA within 3 days. This reduction is dose dependent with a half-optimal decrease at 1% CDCS, and a full decrease at 2% CDCS (4d incubation). Nuclear progestin binding was uniformly low (0.2 - 0.4 pmol/mg DNA) and unaffected by type or concentration of serum, and no consistent change in cytosol or nuclear estrogen receptor levels was observed. These cytoplasmic progestin binding sites are translocated to the nucleus by progesterone, and are similar to estradiol (E2) induced sites by Scatchard binding and sucrose gradient analysis. Similar serum-dependent changes are also observed in the T47D human breast cancer cell line where growth in CDFCS-media results in 4-fold higher progestin binding levels than observed in CDCS-media. Our findings suggest the presence of non-dialyzable stimulatory factor(s) in CDFCS that influence the progestin receptor level and highlight the fact that serum components can alter dramatically the cellular progestin binding activity.
MCF-7人乳腺癌细胞中的孕酮受体水平会随着对雌激素和某些非甾体类抗雌激素的特定反应而增加。在本研究中，我们证明了这些细胞培养过程中存在的血清类型和数量会改变孕激素结合活性水平，但不会改变雌二醇结合活性水平。维持在添加5%活性炭葡聚糖处理的小牛血清（CDCS）的培养基中的MCF-7细胞，每毫克DNA含有0.3 - 0.4皮摩尔的胞质孕酮受体（PRc）。当先前维持在5% CDCS培养基中的细胞转移到含有5%活性炭葡聚糖处理的胎牛血清（CDFCS）的培养基中时，孕激素结合水平在第16天后增加，并在第30至40天稳定在2 - 3皮摩尔/毫克DNA。将这些细胞再转移回5% CDCS培养基中，3天内PRc会降至0.2 - 0.4皮摩尔/毫克DNA。这种降低是剂量依赖性的，在1% CDCS时出现半最佳降低，在2% CDCS（4天孵育）时完全降低。核孕激素结合一直较低（0.2 - 0.4皮摩尔/毫克DNA），且不受血清类型或浓度的影响，并且未观察到胞质或核雌激素受体水平有一致变化。这些细胞质孕激素结合位点会被孕酮转运到细胞核，并且通过Scatchard结合和蔗糖梯度分析与雌二醇（E2）诱导的位点相似。在T47D人乳腺癌细胞系中也观察到了类似的血清依赖性变化，在CDFCS培养基中生长导致的孕激素结合水平比在CDCS培养基中观察到的高4倍。我们的研究结果表明CDFCS中存在不可透析的刺激因子，其会影响孕激素受体水平，并突出了血清成分可显著改变细胞孕激素结合活性这一事实。
