We examined the effects of steroid hormones on the proliferation of transformed mouse Leydig cells (B-1) in serum-free culture condition. Among hormones examined, androgen as well as estrogen enhanced the cell proliferation rate. Hormone binding studies revealed that B-1 cells contained both androgen and estrogen receptors. In addition, androgen-enhanced cell growth was inhibited by antiandrogen, but not by antiestrogen, while estrogen-stimulated cell growth was suppressed by antiestrogen. However, the simultaneous addition of androgen and estrogen did not show an additive effect. Dose-response study on androgen-dependent cell growth revealed that relatively high concentrations (10-7–10-6 m) of dihydrotestosterone were required to obtain the maximum response. This was at least partly explained by the finding that B-1 cells could metabolize dihydrotestosterone into the less active steroids. Finally, B-1 cells were found to grow more rapidly in normal than in castrated male mice.

These results clearly indicate that the proliferation of B-1 cells is stimulated by both androgen and estrogen, which utilize the different receptor systems.

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Supported in part by grants from the Ministry of Education, Tokyo, a Research Grant for Adult Disease, the Osaka Cancer Research Fund, and the Hirai Cancer Research Fund.

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©1989 American Association for Cancer Research.
1989
American Association for Cancer Reseach, Inc.