Comparison of telomerase activity and GSTP1 promoter methylation in ejaculate as potential screening tests for prostate cancer

New diagnostic tools are needed for the early detection of prostatic cancer . The molecular detection of prostate cancer cells in ejaculates was evalua ted using complementary PCR-based methods. LNCaP cells, a cell line derived from prostatic carcinoma, were spiked into normal seminal ejaculates and t he prostatic epithelial component of the specimens was isolated by immunoma gnetic bead sorting, using a monoclonal antibody to prostate-specific membr ane antigen (PSMA). Ejaculates from nine patients with a recent diagnosis o f prostate cancer were processed in a similar Fashion, using LNCaP-spiked a liquots as an internal positive control. Telomerase expression was evaluate d by the telomeric repeat amplification protocol (TRAP) and glutathione S-t ransferase gene promoter (GSTP1) hypermethylation was evaluated by methylat ion-sensitive restriction endonuclease digestion and PCR amplification. Tel omerase activity was detected in LNCaP cells recovered from normal seminal ejaculates but was not found in all nine samples from patients with prostat e cancer. The sensitivity of GSTP1 analysis was similar to telomerase analy sis for the detection of LNCaP cells from normal ejaculate samples but was positive in ejaculates from four out of nine patients with prostate cancer. GSTP1 DNA methylation status is more sensitive than telomerase analysis fo r the detection of malignant cells in seminal ejaculates from patients with prostate cancer. (C) 2000 Academic Press.