Objectives: Epigenetic events such as promoter hypermethylation have been implicated in prostate carcinogenesis. We present a real-time, methylation specific protocol to detect hypermethylation in the promoter region of the GSTP1 gene in benign hyperplasia and adenocarcinoma of the prostate.
Methods: In our preliminary study, 31 prostate cancer and 5 benign prostatic hyperplasia (BPH) tissue samples were analyzed. Genomic DNA was isolated from formalin-fixed and paraffin-embedded specimens and subjected to sodium bisulfite modification, followed by real-time, methylation specific PCR. Patients with prostatic cancer were also subdivided according to their Gleason score, PSA, age and TNM Staging. Prostate cancer cell lines (LNCaP, DU145, PC3) and a BPH cell line (BPH-1) were also tested as controls.
Results: GSTP1 promotor hypermethylation was detected in 28 of the 31 prostate cancer cases (90.3%) and none of the five (0%) BPH cases. Statistical analysis did not reveal a significant correlation between GSTP1 hypermethylation and Gleason score, PSA, age or TNM staging. All prostate cancer cell lines were testes positive for GSTP1 promotor hypermethylation, whereas the BPH cell line (BPH-1) was tested negative.
Conclusion: GSTP1 promotor hypermethylation occurs during carcinogenesis and is considered to be a major event of prostate carcinogenesis. Our data support this thesis and shows that GSTP1 hypermethylation reliably distinguishes between prostate cancer and BPH . Although it is not yet clear at what time during carcinogenesis hypermethylation of the GSTP1 promotor occurs it seems to provide valuable information for prostate cancer screening and diagnosis. Larger studies are underway to determine the potential role for GSTP1 hypermethylation in clinical settings.