[Experimental and clinical study on endocrine therapy of breast carcinoma, with special reference to the nuclear...

The effects of hormones on growths and estrogen receptor (ER) processing were investigated on human breast carcinomas. Two human breast carcinomas, Br-10 (ERC +,ERn-,PgR-) and MCF-7 (ERc +,ERn +,PgR +), serially transplanted into nude mice were used for the experiments. The tumors were treated with estrogen (E) and/or progesterone (P) or tamoxifen (TAM). Although the growth of Br-10 was enhanced by EP and arrested by TAM, ER processing which was observed by E and EP was also observed temporarily by TAM in the early stage, however it was suppressed subsequently. The growth of MCF-7 was dependent on E and the suppression of ER processing was observed in MCF-7 which was transplanted into nude rats and maintained without hormonal treatment. Accordingly, it was suggested that ER processing could be altered by changes in hormonal environment of hosts. ER translocation by priming the exogenous estrogen in vitro was studied in clinical cases. Whereas ERn was detected in 3 out of 20 cases, ER processing was observed in 10 out of 17 ERc positive breast carcinomas (58.8%) and none observed in 3 ERc negativities.