EFFECTS OF GONADAL-STEROIDS ON THE GROWTH OF HUMAN PITUITARY-ADENOMASIN-VITRO

The effects of testosterone (T), dihydrotestosterone (DHT) and methylt rienolone (R 1881) on cell proliferation of eight human pituitary tumo rs in culture wre assessed by [H-3]thymidine incorporation and compare d to those of progesterone (Pg) and 17 beta-estradiol. Receptors for a ndrogens (AR), estrogens (ER) and progesterone (PgR) were characterize d. AR had a significant inhibitory effect on all AR-positive tumors, w hatever their hormonal content. Inhibitory effects of either T and DHT < R1881 < Pg were observed in tumors co-expressing AR and PgR. The in hibitory effect of R 1881 on a PgR-positive/AR-negative tumor suggeste d that R 1881 action was partially PgR-mediated. The effects of either T or the nonaromatizable DHT and R 1881 were unrelated to ER expressi on. We conclude that AR can modulate the growth of human pituitary tum ors through direct receptor-mediated intracellular pathways which may be common to various pituitary cell types.