11-BETA-HYDROXYSTEROID DEHYDROGENASE AND TISSUE-SPECIFICITY OF ANDROGEN ACTION IN HUMAN PROSTATE-CANCER CELL LNCAP

Incubation of whole LNCaP cells in suspension with tritium labeled cor tisol revealed two major and one minor radioactive product. Of the maj or products, one migrated with an R(f) value identical to cortisol (Ke ndall's compound ''F''), and the second migrated with an R(f) value si milar to nonradioactive cortisone (Kendall's compound ''E''); the thir d minor product comigrated with 21-acetylated cortisol. The conversion of cortisol to cortisone was linear with respect to cell number, and conversion reached a plateau after 120 min of incubation at 37 degrees C. One half of the cortisol was converted to cortisone within 2 h of incubation at 37 degrees C. This conversion was nicotine amide dinucle otide (NAD) dependent. Low levels of transcription activation by corti sol were documented in LNCaP cells transfected with glucocorticoid and androgen responsive mouse mammary tumor virus-bacterial chloramphenic ol acetyltransferase chimeric gene (MMTV-CAT). Hormone binding assay a nd transactivation analysis revealed the presence of a functional mine ralocorticoid receptor in LNCaP cells. Treatment of transfectants with F in the presence of carbenoxolone, a potent inhibitor of 11 beta-hyd roxysteroid dehydrogenase (11 beta-HSD), resulted in a two orders of m agnitude increase in measurable CAT activity. The addition of the redu ced form of nicotine amide dinucleotide (NADH) in the presence of 10(- 7) M E stimulated measurable CAT activity in LNCaP cells. In conferrin g aldosterone specificity in mineralocorticoid target tissues, 11 beta -HSD may have an important role as ''gate keeper'' in allowing a speci fic androgen response in hormone responsive LNCaP prostate cancer cell s.