The conversion of an ovariectomy-nonresponsive to an ovariectomy-responsive mammary tumor strain.
MTW9, a transplantable mammary tumor in Wistar Furth rats, shows little growth unless host serum prolactin is increased. This study compares the response to ovariectomy of MTW9-MtT, a tumor developed in rats bearing the mammosomatotropic tumor MtTW10 (serum prolactin 500 to 7000 ng/ml) with MTW9-P developed in rats given chronic perphenazine treatment (4 mg/kg/day). Serum prolactin concentrations were 150 to 600 ng/ml in MTW9-P bearing rats. MTW9-MtT does not regress after ovariectomy but does regress after surgical removal (resection) of MtT. Ovariectomy plus MtT resection leads to greater tumor regression than MtT resection alone. MTW9-P does not regress when perphenazine administration is stopped but does regress after ovariectomy, whether or not rats are given perphenazine. Administration of estradiol (10 mug/day) to rats with complete ovariectomy-induced regression of MTW9-P results in regrowth of tumor. These data suggest that MTW9-P may represent a clone of MTW9 with a lower requirement for prolactin.
D000818:Animals; D002369:Castration; D004958:Estradiol / Q000494:pharmacology; D005260:Female; D013006:Growth Hormone / Q000378:metabolism; D006729:Hormones, Ectopic / Q000378:metabolism; D008325:Mammary Neoplasms, Experimental / Q000097:blood / Q000378:metabolism / Q000628:therapy*; D010546:Perphenazine / Q000494:pharmacology; D011388:Prolactin / Q000378:metabolism / Q000502:physiology*; D051381:Rats; D011920:Rats, Inbred WF
D006729:Hormones, Ectopic; D004958:Estradiol; D011388:Prolactin; D013006:Growth Hormone; D010546:Perphenazine