Diethylstilbestrol inhibits tumor growth and prolactin production in rat pituitary tumors.
Treatment of rats bearing transplantable MtT/W15 tumors with 10 mg of diethylstilbestrol (DES) for 3 weeks led to inhibition of tumor growth. The inhibition of tumor growth was reversible after removal of the DES. Histologic examination revealed decreased mitotic activity; however, DES did not produce cell necrosis. Concomitantly, the anterior pituitary glands of animals treated with DES became hyperplastic, with an increased number of prolactin (PRL)-producing cells. DES resulted in a decreased number of PRL cells in the tumor and decreased serum PRL/tumor weight, compared with that of control rats. There was also an increase in the number of growth hormone (GH) tumor cells and an increased serum GH/tumor weight. 17 beta-Estradiol had an effect similar to that of DES, while progesterone did not inhibit tumor growth or cause pituitary cell hyperplasia. Ovariectomy resulted in a decrease in the tumor growth rate, compared with that of control animals, suggesting that the MtT/W 15 tumors are relatively dependent on estrogens for optimal growth. These results indicate that DES inhibition of MtT/W 15 tumor growth is an excellent model for study of the mechanism of the inhibition of tumor growth and the modification of GH and PRL expression by the tumor cells.
D000818:Animals; D002455:Cell Division; D004054:Diethylstilbestrol / Q000494:pharmacology*; D005260:Female; D013006:Growth Hormone / Q000032:analysis; D009368:Neoplasm Transplantation; D010902:Pituitary Gland / Q000187:drug effects; D010911:Pituitary Neoplasms / Q000378:metabolism / Q000473:pathology*; D011388:Prolactin / Q000096:biosynthesis*; D051381:Rats; D011920:Rats, Inbred WF
D004054:Diethylstilbestrol; D011388:Prolactin; D013006:Growth Hormone