Steroid Biosynthesis<i>in Vitro</i>by Transplantable Interstitial Cell Tumor of Mice. I. Identification and Quantitative Determination of the Metabolites and Intracellular Distribution of the Enzymes Related to Testosterone Formation¹

Abstract

Androgen producing activity of a transplanted tumor of mice, originating in the testicular interstitial cell, was biologically confirmed by the fact that the sex-accessory organs of the tumor-bearing mice did not show any decrease in weight even after removal of the testicular glands. After slices of the testicular interstitial cell tumor which had been transplanted to the mice were incubated in vitro with relabeled pregnenolone and progesterone, respectively, as substrate, not only 17α-hydroxyprogesterone, androstenedione and testosterone, but also the corticosteroids such as deoxycorticosterone, 18-hydroxy-ll-deoxycorticosterone, corticosterone and 11-deoxycortisol were isolated as the metabolites and identified, suggesting that this tumor retained enzyme functions of producing adrenocorticoids as well as androgen. Furthermore, progesterone which was administered as a substrate was catabolized into 20α-and 20β-hydroxypregn-4-en-3-one and 6β-hydroxyprogesterone. The enzyme activities related to androgen formation, such as the Δ5-3β-hydroxysteroid dehydrogenase together with the isomerase, the 17α-hydroxylase, the 17α-hydroxypregnene-C17-C20 lyase, and the 17β-hydroxysteroid dehydrogenase were mainly located in the 800–10,000×g precipitate fraction of the testicular tumor homogenate, while the 20ahydroxysteroid dehydrogenase activity was demonstrated exclusively in the 105,000 ×g supernatant fluid. (Endocrinology83: 659, 1968)