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Androgens are of biological and clinical importance for the growth and development of breast cancer in women, and the androgen receptor (AR) has been shown to be a predictor of tumor differentiation. In the present study, we investigated the relationship between AR status and testosterone and 5 alpha-dihydrotestosterone (DHT)-dependent proliferation of the human breast carcinoma cell lines MCF-7, T47-D, MDA-MB 435S and BT-20. AR status was studied by means of immunocytochemistry and Western blot analysis. All four cell lines stained positively for AR. Western blot analysis revealed a strong expression of AR in MCF-7, in contrast to BT-20 cells. According to proliferation kinetics, we observed a significant (p < or = 0.05) dose-dependent inhibition of cell growth by testosterone and DHT treatment in all four cell lines. In the estrogen receptor (ER)-negative cell lines BT-20 and MDA-MB 435S, testosterone was a more potent inhibitor of cell proliferation than DHT (p < or = 0.05), in contrast to the ER-positive cells lines MCF-7 and T47-D, in which a stronger inhibition of proliferation was achieved by DHT. A partial transformation of testosterone to estrogen in ER-positive cells might be an explanation for this effect. Our data favor a possible role of androgens in growth regulation of breast cancer. Clinical studies are needed to analyze the importance of AR as a possible predictor in response to endocrine therapy of breast cancer.
Ortmann et al. (Tue,) studied this question.