Expression of aromatase and 17β-hydroxysteroid dehydrogenase types 1, 7 and 12 in breast cancer

It is known that there is a local biosynthesis of estradiol (E2) in breast carcinoma. The steroidogenic enzymes involved in E2 formation are aromatase which transforms testosterone into E2 and androstenedione into estrone (E1) and reductive 17β-hydroxysteroid dehydrogenases (17β-HSDs) which convert E1 into E2. Using immunocytochemistry, we have studied the expression of aromatase and the three reductive 17β-HSDs 17β-HSD types 1, 7 and 12 in 41 specimens of female human breast carcinoma and adjacent non-malignant tissues. These results were correlated with the estrogen receptor α (ERα) and β (ERβ), progesterone receptor, androgen receptor, CDC47 and c-erb B-2 expressions and with the tumor stages. Aromatase was found in 58%, 17β-HSD type 7 in 47% and 17β-HSD type 12 in 83% of the breast cancer specimens. The 17β-HSD type 1 could be detected in only one tumor. A significant correlation was observed between the aromatase, 17β-HSD type 7 and 17β-HSD type 12 expression, as well as between each of the two enzymes 17β-types 7 and 12 and the ERβ expression. The expression of 17β-HSD type 12 was significantly higher in breast carcinoma specimens than in normal tissue. There was also a significant association of CDC 47 expression with ERβ, AR and 17β-HSD type 12. The results indicate that aromatase, 17β-HSD type 7 and 17β-HSD type 12, but not 17β-HSD type 1, are commonly expressed in human breast cancer. Moreover, the high expression of both 17β-HSD type 12 and ERβ in breast carcinoma cells may play a role in the development and/or progression of breast cancer.