The authors have examined five human breast cancer cell lines in continuous tissue culture for androgen responsiveness. One of these cell lines shows a 2 to 4 fold stimulation of thymidine incorporation into DNA, apparent as early as 10 hr following androgen addition to cells incubated in serum free medium. This stimulation is accompanied by an acceleration in cell replication. Antiandrogens [cyproterone acetate (6 chloro 17α acetate 1,2α methylene 4,6 pregnadiene 3,20 dione) and R2956 (17β hydroxy 2,2,17α trimethoxyestra 4,9,11 triene 1 one)] inhibit both protein and DNA synthesis below control levels and block androgen mediated stimulation. Prolonged incubation (greater than 72 hr) in antiandrogen is lethal. The MCF 7 cell line contains high affinity receptors for androgenic steroids demonstrable by sucrose density gradients and competitive protein binding analysis. By cross competition studies, androgen receptors are distinguishable from estrogen receptors also found in this cell line. Concentrations of steroid that saturate androgen receptor sites in vitro are about 1000 times lower than concentrations that maximally stimulate the cells. Changes in quantity and affinity of androgen binding to intact cells at 37°C as compared wih usual binding techniques using cytosol preparation at 0° do not explain this difference between dissociation of binding and effect. However, this difference can be explained by conversion of [3H]5α dihydrotestosterone to 5α androstanediol and more polar metabolites at 37°. An examination of incubation media, cytoplasmic extracts, and crude nuclear pellets reveals probable conversion of [3H]testosterone to [3H± 5α dihydrotestosterone. The data provide compelling evidence that some human breast cancer, at least in vitro, may be androgen dependent.
|Original language||English (US)|
|Number of pages||9|
|State||Published - Dec 1976|
ASJC Scopus subject areas
- Cancer Research