Real-time RT-PCR for the measurement of prostate-specific antigen mRNA expression in benign hyperplasia and adenocarcinoma of prostate.

Abstract

Since PSA is supposed to play an active role in the progression of prostate cancer, we applied a quantitative RT-PCR to measure the absolute levels of prostate-specific antigen (PSA) mRNA expression in benign and malignant prostatic tissue. Consecutive fine needle prostate biopsy material from 59 patients (43 with prostate adenocarcinoma and 16 with benign prostatic hyperptrophy; BPH) was used for the measurement of PSA mRNA expression. In addition, we evaluated the correlation between PSA synthesis and PSA circulating levels in the same patients. The relationship between PSA mRNA expression and histological grade was also evaluated. PSA mRNA was measured with a quantitative RT-PCR, based on the use of fluorogenic probes, according to the TaqMan reaction system. The mRNA expression for PSA in prostate adenocarcinoma biopsies was highly variable, ranging from 2 x 10(4) to 2.1 x 10(8) molecules/microg total RNA with a mean value of 2.5 x 10(7) and significantly higher (p = 0.006) than that found in BPH patients (mean: 1.3 x 10(6) and range: 6.9 x 10(2) to 8 x 10(6)). The mRNA PSA expression in needle biopsy material did not seem to be related to PSA circulating levels in prostate cancer patients (r = 0.281), whereas in BPH patients the two parameters correlated significantly (r = 0.667, p < 0.01). A reduction of PSA mRNA expression in samples with a lower grade of differentiation (Gleason score 9-10) was also observed. Even though a mean increase of PSA expression was demonstrated in cancer samples, this small difference does not confirm a significant role of PSA proteolytic activity in prostate cancer progression. In conclusion, the assay procedure we proposed represents a reliable basis for more extensive study of PSA physiopathology in prostate cancer.