Immunolocalization of estrogen-producing and metabolizing enzymes in benign breast disease: comparison with normal breast and breast carcinoma

Abstract

It is well known that estrogens play important roles in the cell proliferation of breast carcinoma. Benign breast disease (BBD) contains a wide spectrum of diseases, and some are considered an important risk factor for subsequent breast carcinoma development. However, the significance of estrogens in BBD has remained largely unknown. Therefore, in this study, we examined tissue concentrations of estrogens and immunolocalization of estrogen-producing/metabolizing enzymes in BBD, and compared these findings with those in the normal breast and ductal carcinoma in situ (DCIS). Tissue concentration of estradiol in BBD (n = 9) was significantly (3.4-fold) higher than normal breast (n = 9) and nearly the same (0.7-fold) as in DCIS (n = 9). Immunoreactivity of estrogen sulfotransferase in BBD was significantly lower (n = 82) than normal breast (n = 28) but was not significantly different from DCIS (n = 28). Aromatase and steroid sulfatase immunoreactivities tended to be higher (P = 0.07) in BBD than in normal breast, and 17β-hydroxysteroid dehydrogenase type 1 immunoreactivity was significantly higher in BBD than normal breast in the postmenopausal tissues. Immunoreactivity of estrogen and progesterone receptors was also significantly higher in BBD than normal breast. These results suggest that tissue concentration of estradiol is increased in BBD at a level similar to DCIS, which is considered mainly due to loss of estrogen sulfotransferase expression. Increased local estradiol concentration in BBD due to aberrant expression of estrogen-producing/metabolizing enzymes may play important roles in the accumulation of estradiol-mediated growth and/or subsequent development of breast carcinoma.

Figure 1

Tissue concentrations of estradiol (a) and estrone (b) in benign breast disease (BBD). Data are represented as box and whisker plots. The median value is represented by a horizontal line in each box. The 75th (upper margin) and 25th (lower margin) percentiles of the values are shown. The upper and lower bars indicate the 90th and 10th percentiles, respectively. Statistical analysis was carried out using the Mann–Whitney U‐test. P‐values <0.05 were considered significant, and are indicated in bold. DCIS, ductal carcinoma in situ; normal, breast tissue with no significant pathological abnormalities.

Figure 2

Representative illustrations of immunohistochemistry for estrogen‐producing/metabolizing enzymes in benign breast disease. Aromatase immunoreactivity was negative in normal breast (a), but was detected in the epithelium of the papilloma (b,c). Aromatase immunolocalization was observed in a part of the hyperplastic (b) or simple epithelium in the same case (c). Steroid sulfatase immunoreactivity was not detected in the normal breast (d), but it was positive in the epithelium of the papilloma (e,f). Steroid sulfatase immunoreactivity was observed in a part of the hyperplastic (e) or simple epithelium in the same case (f). Estrogen sulfotransferase immunoreactivity was detected in normal epithelial cells (g), but was negative in fibroadenoma (h). Estrogen sulfotransferase immunoreactivity was positive in various degree of hyperplastic epithelium in usual ductal hyperplasia (i). M, mild hyperplasia component (three to four cell layers thick); S, severe (or florid) hyperplasia component (solid duct hyperplasia). Bar = 100 μm.

Figure 3

Estrogen receptor (ER) and progesterone receptor (PR) immunoreactivity in benign breast disease (BBD). (a,c) Estrogen receptor (a) and progesterone receptor (c) immunoreactivity was detected in the nuclei of epithelial cells in this case of fibroadenoma. Images show the same area. Bar = 100 μm. (b,d) Association of ER (b) and PR (d) labeling indexes (LI) between BBD and normal breast or ductal carcinoma in situ (DCIS). Data are represented as box and whisker plots. The statistical analysis was carried out using the Mann–Whitney U‐test. P‐values <0.05 were considered significant, and are shown in bold.