The effects of
estrogens on the growth and
enzyme activities for
androgen synthesis in a mouse
Leydig cell tumor line (T 124958-R) were studied. The s.c. implantation of a
diethylstilbestrol pellet resulted in a marked enhancement of the
tumor growth.
5 alpha-Reductase activity (nmol/g/h) in
tumors rapidly grown in the presence of
diethylstilbestrol pellet was 4 times higher than that in
tumors slowly grown in the absence of
diethylstilbestrol, whereas an inverse relation was found for 17 beta-hydroxysteroid
oxidoreductase activity. 17-Hydroxylase activities were similar in both
tumors. The major C21- and C19-steroids formed from
progesterone by the
tumors grown in the presence of
estrogen were 5 alpha-
steroids such as 3 alpha- or 3 beta-hydroxy-5 alpha-pregnan-20-one, 3 alpha, 17-dihydroxy-5 alpha-pregnan-20-one,
androsterone, and
5 alpha-androstane-3 alpha, 17 beta-diol, whereas the major
steroids formed by the
tumors in the absence of
estrogen were 4-ene-3-ketosteroids such as
20 alpha-hydroxy-4-pregnen-3-one, 17-hydroxy-4-pregnene-3,20-dione, and
testosterone. Furthermore, 10(-8) M of
17 beta-estradiol added in serum-free medium for 10 days significantly enhanced
5 alpha-reductase activities per 10(6) cells but significantly inhibited 17 beta-hydroxysteroid
oxidoreductase activity in primary cell culture. These results indicate that
estrogens stimulate the growth of T 124958-R in vivo and that
estrogens may directly enhance
5 alpha-reductase activity but inhibit 17 beta-hydroxysteroid
oxidoreductase activity in T 124958-R cells.