Real-time quantitative RT-PCR analysis of laser microdissected tissue is considered the most accurate technique for determining tissue gene expression. The discovery of estrogen receptor beta (ERβ) has focussed renewed interest on the role of estrogen receptors in prostate cancer, yet few studies have utilized the technique to analyze estrogen receptor gene expression in prostate cancer.METHODS.
Fresh tissue was obtained from 11 radical prostatectomy specimens and from 6 patients with benign prostate hyperplasia. Pure populations of benign and malignant prostate epithelium were laser microdissected, followed by RNA isolation and electrophoresis. Quantitative RT-PCR was performed using primers for androgen receptor (AR), estrogen receptor beta (ERβ), estrogen receptor alpha (ERα), progesterone receptor (PGR) and prostate specific antigen (PSA), with normalization to two housekeeping genes. Differences in gene expression were analyzed using the Mann-Whitney U-test. Correlation coefficients were analyzed using Spearman's test.RESULTS.
Significant positive correlations were seen when AR and AR-dependent PSA, and ERα and ERα-dependent PGR were compared, indicating a representative population of RNA transcripts. ERβ gene expression was significantly over-expressed in the cancer group compared with benign controls (P<0.01). In contrast, PGR expression was significantly down-regulated in the cancer group (P<0.05). There were no significant differences in AR, ERα or PSA expression between the groups. This study represents the first to show an upregulation of ERβ gene expression in laser microdissected prostate cancer specimens.CONCLUSIONS.
In concert with recent studies the findings suggest differential production of ERβ splice variants, which may play important roles in the genesis of prostate cancer. Prostate 69: 810-819, 2009.