The conversion of androstenedione to estrone, estradiol, and testosterone in breast tissue

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Abstract

In vitro studies have been carried out to compare the conversion of androstenedione to testosterone, estrone and 17β-estradiol in breast adipose and parenchymal tissue from patients undergoing reduction mammoplasty and in breast adipose and carcinoma tissue from patients undergoing mastectomy.

Under the established conditions of the incubations, all tissues are active in the conversion of androstenedione to testosterone and estrone. Testosterone formation is 10-fold greater in carcinoma and adipose tissue than in parenchymal breast tissue. Estrone formation is greater in carcinoma tissue than in parenchymal or adipose tissue. The ratio of testosterone to estrone formation is 5 to 10-fold greater in adipose tissue than in parenchymal or carcinoma tissue. This difference increases with increasing substrate concentration. Although the testosterone to estrone ratio in parenchymal and carcinoma breast tissues is similar, the absolute conversion of androstenedione to both testosterone and estrone is greater in carcinoma tissue. Breast adipose and carcinoma tissues convert androstenedione to 17β-estradiol, however, no 17β-estradiol was detected in incubations of parenchymal breast tissue.

These local differences in the formation of androgens and estrogens may be an important factor in determinine the bioloeical resoonse of peripheral tissues.

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    Part of this paper was presented at the 60th Annual Meeting of the Endocrine Society, Miami, 1978. This work was supported by a grant from The Medical Research Council of Canada MA 6251 and by a grant from the National Cancer Institute of Canada.

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