Immunohistochemical and biochemical analysis of a human Sertoli-Leydig cell tumor: autonomous steroid production characteristic of ovarian theca cells.

OBJECTIVE: To ascertain the steroidogenic profile and location of steroidogenic enzymes in a steroid-secreting Sertoli-Leydig cell tumor of the ovary. METHODS: Steroid levels from peripheral, left ovarian (tumor), and right ovarian venous blood were measured. Tumor tissue was examined for the steroidogenic enzymes 17 alpha-hydroxylase (P450c17) and 3 beta-hydroxysteroid dehydrogenase (3 beta HSD) by immunohistochemistry. Tumor cells were isolated and incubated in serum-free media. Thereafter, media were analyzed for steroid production, steroidogenic response to effectors, and metabolism of radiolabeled pregnenolone and androstenedione. RESULTS: Levels of C19 steroids and 17-hydroxyprogesterone (17OHP) were elevated in peripheral blood. The majority (80%) of steroids in serum from the left ovarian vein (tumor) were C19 steroids (dehydroepiandrosterone [DHEA], 45%; androstenedione, 27%, testosterone, 7%, with 13% 17OHP, 7% progesterone, and less than 1% estradiol (E2). Immunoreactivity for both P450c17 and 3 beta HSD was identified in clusters of large cells surrounded by nonimmunoreactive cells composing cord-like structures. Of the steroids that accumulated in the incubation medium of unstimulated, freshly isolated tumor cells, 84% were C19 steroids (DHEA, 44%; androstenedione, 36%; testosterone 2%, with 16% 17OHP and less than 1% progesterone and E2. Basal steroid production was not stimulated by LH or FSH. However, treatment with forskolin (10 mumol/L), dibutyryl cAMP (1 mmol/L), or steroid precursors (22-hydroxycholesterol, 1 mumol/L; pregnenolone, 1 mumol/L) increased the production of all steroids measured. Forskolin treatment increased androstenedione (fivefold), DHEA (tenfold), and 17OHP (40-fold) compared with basal levels. Incubation of freshly isolated cells with [3H]pregnenolone demonstrated the ability of these cells to metabolize this C21 steroid precursor to androstenedione, DHEA, and 17OHP. However, [3H]androstenedione was not readily metabolized by these cells to either estrone or testosterone. CONCLUSIONS: The steroidogenic properties of a steroid hormone-producing tumor were described. Cells isolated from this tumor produced steroids similar to those secreted by ovarian theca cells. These properties suggest that certain ovarian steroidogenic tumor cells may be an appropriate model for ovarian theca cells and could be used to develop steroid-secreting cell lines.