[Dna synthesis and expression of steroid receptors in cells of human breast carcinoma].

In order to observe receptor expression (ER and PgR) in human breast cancer cells during the S-phase of the cellular cycle, we evaluated 21 tumoral samples using a double labeling immunocytochemical-autoradiographic assay. In 16 of these we have verified that expression of ER and PgR is not influenced by incubation with 3H-Thymidine for 60 minutes. The results also demonstrated that receptor expression during the S-phase is more common in postmenopausal tumors and is principally dependent on percentages of ER+ (p < 0.01) and PgR+ (p < 0.01) cells; moreover, proliferative activity occurs almost exclusively in ER- (p = 0.003) and Pgr- (p = 0.001) cellular sub populations and the presence of PgR, but not of ER, is related to arrest of DNA synthesis (p = 0.02).