Nuclei of stroma: site of highest estrogen concentration in human benign prostatic hyperplasia

In an earlier publication we found significantly more estrogen receptor-positive cases in the stroma if compared with the epithelium of human benign prostatic hyperplasia (BPH). We were therefore interested to find out whether this preferential assay of estrogen receptor in stroma is reflected by a higher estrogen content in this tissue fraction. Estradiol (E2) and estrone (E1) were measured by RIA in whole BPH tissue, stroma, and epithelium as well as in the nuclear fraction of stroma and epithelium. For comparison, E2 and E1 were measured in blood also. The main results are as follows: 1) In all BPH samples the E2 (26.0 +/- 3.5 (SEM) pg/g (n = 20)) and E1 (53.5 +/- 7.4 (14)) content was significantly higher than in the corresponding plasma (E2: 17.5 +/- 2.3 pg/ml (11); E1: 26.5 +/- 4.4(7)), the mean ratio of E2/E1 was 0.52 and 0.69 for BPH and plasma, respectively; 2) in stroma significantly more E2 (53.6 +/- 7.8 fmol/mg DNA (18)) and E1 (55.9 +/- 8.4 (12)) were measured than in epithelium (E2: 15.7 +/- 1.9 (16); E1: 20.7 +/- 3.2 (13)); 3) in nuclei of stroma significantly higher E2 (38.0 +/- 5.3 fmol/mg DNA (20)) and E1 (19.2 +/- 4.8 (14)) concentrations were present than in epithelium (E2: 6.8 +/- 3.1 (19); E1: 2.5 +/- 0.5 (13)), the mean ratio of E2/E1 for the nuclear fractions of stroma (2.3) and epithelium (2.7) increased dramatically if compared with the respective ratio in whole BPH tissue. In conclusion, there is a distinct accumulation of estrogens in the nuclei of stroma, E2 concentration being significantly higher than E1. These data support the hypothesis that E2 could play a preferential role in stimulating the growth of the BPH stroma.