Feedback effects of mammary gland tumors on the host pituitary prolactin cell.
Prolactin (PRL) cells in pituitary glands of F-344 female rats bearing transplantable mammary gland adenocarcinomas (13762, 3230) were smaller, contained less intracellular hormone, and released less hormone in culture relative to non tumor-bearing littermates. In some instances removal of the tumor by surgery or chemotherapy (PAM) resulted in restoration of function in vitro. On the other hand, PRL cells from pituitaries of breast cancer patients were often hypertrophied. Since these patients had mastectomies prior to hypophysectomy, the data are consistent with the hypothesis that the tumor exerts negative feedback at the pituitary or hypothalamic level. In support of this hypothesis we have discovered a potent PIF in rat serum. In addition, an experimental protocol involving a) encapsulation of pituitary cells in Amicon hollow fibers, b) their implantation in ectopic sites and c) their subsequent in vitro culture yields data which suggest that the brain of the tumor bearing rat suppresses PRL release. It is suggested that decreased PRL cell function in animals bearing certain mammary tumors ultimately favors metastatic activity of the tumor cell.
D000818:Animals; D001943:Breast Neoplasms / Q000473:pathology; D002469:Cell Separation; D002478:Cells, Cultured; D004967:Estrogens / Q000494:pharmacology; D005246:Feedback; D005260:Female; D006801:Humans; D008325:Mammary Neoplasms, Experimental / Q000378:metabolism / Q000473:pathology* / Q000628:therapy; D010902:Pituitary Gland / Q000166:cytology / Q000473:pathology*; D011388:Prolactin / Q000378:metabolism*; D051381:Rats; D011916:Rats, Inbred F344
D004967:Estrogens; D011388:Prolactin