Background: Methylation of regulatory sequences near GSTP1, which encodes the π class glutathione S-transferase, is the most common epigenetic alteration associated with prostate cancer. We determined whether the quantitation of GSTP1 methylation in histopathologically distinct prostate tissue samples could improve prostate cancer detection. Methods: We used a fluorogenic real-time methylation-specific polymerase chain reaction (MSP) assay to analyze cytidine methylation in the GSTP1 promoter in prostate tissue samples from 69 patients with early-stage prostatic adenocarcinoma (28 of whom also had prostatic intraepithelial neoplasia lesions) and 31 patients with benign prostatic hyperplasia. The relative level of methylated GSTP1 DNA in each sample was determined as the ratio of MSP-amplified GSTP1 to MYOD1, a reference gene. We also performed a prospective, blinded investigation to quantitate GSTP1 promoter methylation in sextant prostate biopsy specimens from 21 additional patients with elevated serum prostate-specific antigen levels, 11 of whom had histologically identified adenocarcinoma and 10 of whom had no morphologic evidence of adenocarcinoma. All data were analyzed by using nonparametric two-sided statistical tests. Results: The median ratios (and interquartile ranges) of MSP-amplified GSTP1 to MYOD1 in resected benign hyperplastic prostatic tissue, intraepithelial neoplasia, and adenocarcinoma were 0 (range, 0–0.1), 1.4 (range, 0– 45.9), and 250.8 (range, 53.5–697.5), respectively; all of these values were statistically significantly different (P<.001). The median ratios of MSP-amplified GSTP1 to MYOD1 in the prospectively collected sextant biopsy samples were 410.6 for the patients with adenocarcinoma and 0.0 for the patients with no evidence of adenocarcinoma (P<.001). Conclusion: Quantitation of GSTP1 methylation accurately discriminates between normal hyperplastic tissue and prostatic carcinoma in small samples of prostate tissue and may augment the standard pathologic/histologic assessment of the prostate.

TMPRSS2-ETS gene fusions have been found recurrently in prostate carcinomas, but not in the presumed precursor lesion, high-grade prostatic intraepithelial neoplasia (HGPIN). However, HGPIN lesions may share chromosomal changes with prostate cancer. To determine the relative order of genetic events in prostate carcinogenesis, we have analyzed 34 prostate carcinomas, 19 paired HGPIN lesions, 14 benign prostate hyperplasias, and 11 morphologically normal prostatic tissues for TMPRSS2-ERG and TMPRSS2-ETV1 rearrangements and genomic imbalances. TMPRSS2 exon 1 was fused in-frame with ERG exon 4 in 17 of 34 (50%) prostate carcinomas and in 4 of 19 (21%) HGPIN lesions, but in none of controls. The findings were further validated by sequencing analysis and by the real-time polymerase chain reaction quantification of TMPRSS2-ERG fusion transcript and the ERG exons 5/6:exons 1/2 expression ratio. Chromosome copy number changes were detected by comparative genomic hybridization in 42% of clinically confined carcinomas and in none of the 16 HGPIN lesions analyzed. We demonstrate for the first time that the TMPRSS2-ERG fusion gene can be detected in a proportion of HGPIN lesions and that this molecular rearrangement is an early event that may precede chromosome-level alterations in prostate carcinogenesis.

Growing cancer incidence and mortality worldwide demands development of accurate biomarkers to perfect detection, diagnosis, prognostication and monitoring. Urologic (prostate, bladder, kidney), lung, breast and colorectal cancers are the most common and despite major advances in their characterization, this has seldom translated into biomarkers amenable for clinical practice. Epigenetic alterations are innovative cancer biomarkers owing to stability, frequency, reversibility and accessibility in body fluids, entailing great potential of assay development to assist in patient management. Several studies identified putative epigenetic cancer biomarkers, some of which have been commercialized. However, large multicenter validation studies are required to foster translation to the clinics. Herein we review the most promising epigenetic detection, diagnostic, prognostic and predictive biomarkers for the most common cancers.

Purpose: Promoter hypermethylation is an alternative pathway for gene silencing in neoplastic cells and a promising cancer detection marker. Although quantitative methylation-specific PCR (QMSP) of the GSTP1 promoter has demonstrated near perfect specificity for cancer detection in prostate biopsies, we postulated that identification and characterization of additional methylation markers might further improve its high (80–90%) sensitivity.

Purpose: Aberrant promoter hypermethylation of several known or putative tumor suppressor genes occurs frequently during the pathogenesis of prostate cancers and is a promising marker for cancer detection. We sought to develop a test for prostate cancer based on a quantitative methylation-specific polymerase chain reaction (QMSP) of multiple genes in urine sediment DNA. Patients and Methods: We tested urine sediment DNA for aberrant methylation of nine gene promoters (p16INK4a, p14^ARF, MGMT, GSTP1, RARβ2, CDH1 [E-cadherin], TIMP3, Rassf1A, and APC) from 52 patients with prostate cancer and 21 matched primary tumors by quantitative fluorogenic real-time polymerase chain reaction. We also analyzed urine sediments from 91 age-matched individuals without any history of genitourinary malignancy as controls. Results: Promoter hypermethylation of at least one of the genes studied was detected in urine samples from all 52 prostate cancer patients. Urine samples from the 91 controls without evidence of genitourinary cancer revealed no methylation of the p16, ARF, MGMT, and GSTP1 gene promoters, whereas methylation of RARβ2, TIMP3, CDH1, Rassf1A, and APC was detected at low levels. Conclusion: Overall, methylation found in urine samples matched the methylation status in the primary tumor. A combination of only four genes (p16, ARF, MGMT, and GSTP1) would theoretically allow us to detect 87% of prostate cancers with 100% specificity. Our data support further development of the noninvasive QMSP assay in urine DNA for early detection and surveillance of prostate cancer.