alpha-Lactalbumin content of rat mammary carcinomas and the effect of pituitary stimulation.

Primary mammary carcinomas induced in nonlactating rats by 7,12-dimethylbenz(alpha)anthracene or methylnitrosourea contained alpha-lactalbumin (alphaLA) in quantities equal to or less than 10% of the amounts found in the parenchyma of the 5-day lactating gland. Only two of five transplantable mammary carcinomas contained alphaLA when growing in rats without hormonal stimulation. Hormonal stimulation maintained by transplantation into lactating females for 146 generations (65 months) failed to induce alphaLA production in dimethylbenz(alpha)anthracene no.1 transplantable mammary carcinoma. Transplantation of a pituitary gland under the kidney capsule of the host (a) increased alphaLA content of primary dimethylbenz(alpha)anthracene-induced mammary carcinomas, (b) reduced alphaLA content of primary methylnitrosourea-induced mammary carcinomas, and (c) was unable to modify the alphaLA levels in five transplantable mammary carcinomas.