STIMULATION OF DNA-SYNTHESIS BY PROLACTIN IN HUMAN-BREAST TUMOR EXPLANTS - RELATION TO PROLACTIN RECEPTORS

Abstract

Breast-cancer tissue from 38 patients was tested for prolactin sensitivity by measuring both 16 h (3H)dT incorporation in tissue fragments during 24 h organ cultures, and prolactin receptors in tumor specimens. A stimulation of DNA synthesis by prolactin was observed in 6/38 (16%) cases; the stimulation was maximum with physiological concentrations of prolactin (0.05-0.2 .mu.g/ml medium). The stimulation of DNA synthesis never occurred in the absence of prolactin receptors. There is no relation between the response to prolactin and estradiol or progesterone receptor levels, but in 4 cases the stimulation was observed when the 3 receptors were present. Finally, the response to the stimulation was independent of the clinical stage of the patient.