The conversion in vitro of 17-hydroxypregnenolone to cortisol by a human adrenal tumor.

In the generally accepted schemes for the biosynthesis of adrenal cortical steroids (l-3), progesterone* is represented as the branch point in the formation of 17-hydroxycorticosteroids (Reactions D and F, Fig. l), on the one hand, and the 17-deoxycorticosteroids (Reaction E, Fig. l), on the other. Savard et al. (4) found that incubation of slices of an interstitial cell tumor of the testis with acetate-l-Cl4 yielded labeled testosterone, androstenedione, ll@-hydroxyandrostenedione, dehydroepiandrosterone, and 17.hydroxyprogesterone, but no labeled progesterone. The same tissue was found to utilize progesterone effectively as a precursor for 17.hydroxyprogesterone and those steroids derived from it. These results led us to investigate two pathways for the formation of 17-hydroxyprogesterone (Fig. 1) by a single incubation of slices of a human adrenal cortical tumor with both progesterone-4-C14 and 17-hydroxypregnenolone-7o(-H3.