EFFECT OF PROLACTIN ON GROWTH AND ESTROGEN-RECEPTOR LEVEL OF HUMAN BREAST-CANCER CELLS (MCF-7)

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  • 1 January 1977
    • journal article
    • research article
    • Vol. 37  (3) , 792-799
Abstract
Intracellular specific 17.beta.-estradiol binding in the human breast cancer cell line, MCF-7, was modified by prolactin. Ovine and human prolactin doubled the estradiol receptor (E2R) level, but the latter was at least 10 times more stimulatory on a concentration basis. Most of the E2R complex (.apprx. 80%) was transported to the nucleus, and prolactin stimulation was reflected in elevated nuclear uptake of 3H-17.beta.-estradiol. Neither ovine or human prolactin altered the growth rate of the cells when E2R stimulation was maximal. Insulin (10 .mu.g/ml) stimulated 3H-thymidine incorporation and total DNA content but had no apparent effect on E2R concentration. At 10-4 M, N6,O2''-dibutyryl cyclic[c]AMP increased insulin stimulation of 3H-thymidine incorporation and induced prolactin stimulation of apparent DNA synthesis. Theophylline (10-3 M) blocked both of these effects of N6,O2''-dibutyryl cAMP. The possible mechanism implicating prolactin as an effector of differentiation and growth of MCF-7 cells is discussed.