CASEIN AND ALPHA-LACTALBUMIN MESSENGER-RNA IN EXPERIMENTAL BREAST-CANCER

Abstract

A transplantable rat mammary carcinoma (R3230AC) was previously shown to contain prolactin receptors. The present objective was to determine whether these receptors were functional by measuring specific markers of prolactin action: casein and .alpha.-lactalbumin (.alpha.LA) mRNA. Total RNA extracts were translated in a wheat germ cell free system. Newly synthesized 3H-casein and 3H-.alpha.LA were separately precipitated with specific antibodies and identified by their mobilities on sodium dodecyl sulfate acrylamide gels and competition with nonradioactive casein and .alpha.LA. Casein and .alpha.LA mRNA were present in unstimulated tumors grown in virgin rats. Casein mRNA, but not .alpha.LA, mRNA was stimulated by injections of exogenous ovine prolactin or perphenazine, an agent that stimulates endogenous prolactin. This response was selective in that total mRNA was not significantly altered by prolactin.