Homogenates of
estrogen-responsive mouse Leydig cell
tumors (T 124958-R and T 22137) or 28- and 120-day-old mouse testes were incubated with [3H]
progesterone or [14C]
4-androstene-3,17-dione in the presence of
NADPH, and
progesterone metabolism and
enzyme activities were estimated. The growth of T 124958-R
tumor transplanted in BALB/c mice was markedly stimulated by estrogenization of host mice, but the growth of T 22137
tumor was evidently suppressed by the estrogenization. The major C21-17-OH-steroids and C19-steroids formed from
progesterone by both
tumors and the testes of immature mice were 5 alpha-
steroids, such as 3 alpha,17-dihydroxy-5 alpha-pregnan-20-one,
5 alpha-androstane-3,17-dione,
androsterone, 3 beta-hydroxy-5 alpha-androstan-17-one and
5 alpha-androstane-3 alpha,17 beta-diol. In contrast, the major
steroids formed by the testes of adult mice were
testosterone and
4-androstene-3,17-dione, and no or little 5 alpha-
steroids were produced.
5 alpha-Reductase activities in both
tumor cells (40-50 nmol/l X 10(8) cells per h) were also found to be approx. 5-6 times higher than that in Leydig cells of adult mouse testes (8 nmol/l X 10(8) Leydig cells per h), though 17-hydroxylase activity was much higher in the Leydig cells of adult testes (730 nmol/l X 10(8) Leydig cells per h) than in both
tumor cells (1-7 nmol/l X 10(8) cells per h). Furthermore, the presence of significant amounts of endogenous
androsterone and/or
5 alpha-androstane-3 alpha,17 beta-diol was demonstrated in both
tumors by radioimmunoassay. The present results demonstrate for the first time that C19-5 alpha-
steroids are major C19-steroid products (immature type of testicular
androgen production) in
Leydig cell tumor lines.