Transformation of the 10S androgen receptor in a hamster ductus deferens tumor cell line.

Androgen receptor transformation was studied in a hamster ductus deferens tumor cell line using whole cell and cell-free labeling conditions. After cell incubations with [3H] dihydrotestosterone at 0 or 23 C, receptor was recovered predominantly in cytosol as 406,000 mol wt (10.1 +/- 0.4S; 89 +/- 1 A) and 237,000 mol wt (7.1 +/- 0.4S; 74 +/- 1 A). At 37 C, increasing amounts of receptor were retained with time by nuclei as receptor size decreased to 127,000 mol wt (5.5 +/- 0.3S; 51 +/- 2 A). The half-time of nuclear association was approximately 3 min at 37 C. DNA-binding activity was acquired upon conversion of the 10S receptor to 7S and 5.5S forms. The use of serum-free culture conditions ruled out the possible involvement of serum proteins in the formation of multiple receptor forms. In cell-free preparations, dihydrotestosterone binding was required for receptor dissociation from 10S to 7S, which at short time intervals was enhanced by mercaptoethanol. It is concluded that the 7S receptor is a transformation intermediate that displays DNA-binding activity but is not well retained in nuclei. Complete androgen receptor transformation is a steroid- and temperature-dependent reaction involving a decrease in receptor size from 10S to 5.5S.