Abstract

PIP: The authors prepared the prolactin marker with iodine-125 and made iodine-125-human prolactin and iodine-125-sheep prolactin. To make the complex, iodine-125-human prolactin was incubated with prolactin receptors isolated from female rat liver cell membranes. This complex is reversible and can be replaced by cold human prolactin. Studies with mammary glands of various animals have indicated that the prolactin receptor seemed to be a peptide or a protein of macromolecules in chemical nature. Estrogen enhanced the binding ability of iodine-125-sheep prolactin to prolactin receptor of rat liver cell membranes. The mammary cells from hyposectomized animals lost the binding ability, and this ability was not recovered even by estrogen administration. In experimental animals, the growth of mammary cancer, induced by dimethyl benzanthracene, was enhanced by the administration of prolactin and reduced by the introduction of an antiprolactin serum. Ergocornine which would suppress the secretion of prolactin also reduced the cancer growth. The factors which would increase the secretion of prolactin increased the tumor growth. Mammary cancer cells have generally less binding ability to prolactin than the normal mammary cells. These cancer cells in animals seem not to be prolactin dependent and have an autonomic nature. The relationship between prolactin and human mammary cancer is not yet entirely clear. However, there is a possibility that prolactin may play a role in certain mammary cancer. Reports on prolactin receptor in human mammary cancer cells are sparse. Although the authors found estrogen receptor in some mammary cancer cases, they were not able to find a significant amount of prolactin binding ability in these cells.