The metabolism of 7- 3H-pregnenolone was studied in vitro using 16 human breast carcinomas. All mammary tumors transformed pregnenolone to progesterone. All estrogen receptor poor tumors and 4 out of 8 estrogen receptor rich tumors converted pregnenolone to 17-hydroxypregnenolone. Five estrogen receptor poor tumors showed the presence of 17,20-lyase as evidenced by formation of dehydroepiandro-sterone and androstenedione. In two estrogen receptor poor tumors, conversions of pregnenolone to progesterone, 17-hydroxy pregnenolone, dehydroepiandrosterone androstenedione and finally to estradiol was documented, providing a hypothetical pathway for steroid metabolism in human breast cancer. The conversion of pregnenolone to 17-hydroxy-pregnenolone was significantly less in receptor rich tumors and was totally absent in 4 receptor rich tumors with estrogen receptors of over 45 fmol/mg protein.
Bibliographical noteFunding Information:
This investigation was supported in part Grants CA 20530 and CA22467 from the National the Graduate School, University of Minnesota
Copyright 2014 Elsevier B.V., All rights reserved.