Autoradiographic localization of prolactin receptors in 7,12-dimethylbnez[a]anthracene-induced rat mammary carcinoma.

Prolactin receptors were localized by autoradiography in 7,12-dimethylbenz[a]anthracene (DMBA)-induced mammary tumors from rats by incubation of tumor slices with [125I]ovine prolactin. Specific prolactin binding was confined to tumor cells, and nonspecific binding was present in alveolar spaces and connective tissue. In some tumors, all cells contained receptors; in others, up to one-half the cells remained unlabeled. These results suggested that variation in receptor content in DMBA-induced mammary tumors may be caused by two distinct populations of cells--one which contains receptors and another which possesses very few receptor sites or none at all.