Effects of age on growth and ERbeta mRNA expression of canine prostatic cells

Benign prostatic hyperplasia (BPH) is an age-dependent prostatic disease in human males and dogs. The prostatic stromal estrogen level of health control and BPH patients increases significantly with age, while the dihydrotestosterone (DHT) level is not connected with age. Moreover, experimentally estrogens have induced BPH in the presence of androgens. Our aim was to investigate the effects of age on the proliferation and estrogen receptor beta (ER/3) mRNA of canine prostatic epithelial and stromal cells.

Epithelial and stromal cells were isolated from canine prostatic tissues. The proliferation of these cell types from dogs of different ages was assessed by thymidine incorporation assay, while the expression and identification of ERbeta mRNA were performed by RT-PCR and DNA sequence.

Prostatic epithelial cells isolated from 1-year-old dogs exhibited a greater proliferative activity than those of 4-year-old dogs. In contrast, the prostatic stromal cells from 4-year-old dogs proliferated more rapidly than the cells from 1-year-old dogs. ERbeta mRNA expression was detected in the canine prostatic epithelial and stromal cells, decreasing with age. The partial DNA sequence showed that the canine ERbeta sequence shares 90.0%, 87.0% and 83.0% of its nucleotide homology with human, rat and mouse ERbeta, respectively.

The decrease in the expression of ERbeta in prostatic cells with age reduces its negative control over the androgen receptor, associated with the overgrowth of canine prostatic stromal cells, which further induces the development of canine BPH.