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Updated: Sep 10, 2026
In vitro Methylation Assay to Study Protein Arginine Methylation
Published on: October 5, 2014
Quantitative GSTP1 methylation clearly distinguishes benign prostatic tissue and limited prostate adenocarcinoma
Susan V Harden1, Zhongmin Guo, Jonathan I Epstein
1Department of Otolaryngology-Head and Neck Surgery, Head and Neck Cancer Division, The Johns Hopkins University School of Medicine, Baltimore, Maryland, USA.
Purpose:
Hypermethylation of the glutathione S-transferase gene (GSTP1) is the most common (greater than 90%) reported epigenetic alteration in prostate cancer. It occurs early in cancer progression and it is a promising marker for detecting organ confined disease. To evaluate its use as a diagnostic tool for cancer we used quantitative GSTP1 methylation to test for the presence of cancer in 45 prostate needle biopsy samples.
Materials And Methods:
Paraffin tissue samples from 45 patients with minute foci of intermediate grade prostatic adenocarcinoma or benign disease on needle biopsy were tested for GSTP1 hypermethylation using quantitative fluorogenic real-time methylation specific polymerase chain reaction. This assay was performed in blinded fashion without previous knowledge of the histopathological diagnosis.
Results:
DNA from 29 of the 45 paraffin samples was amenable to polymerase chain reaction amplification. In these 29 samples GSTP1 methylation was detected in 11 of 15 cases of limited cancer and in 0 of 14 of benign disease (2-sided Fisher's exact test, p <0.0001). Thus, this assay had 73% sensitivity, 100% specificity, 100% positive and 78% negative predictive values.
Conclusions:
Quantitation of GSTP1 hypermethylation accurately detects the presence of cancer even in small, limited tissue samples. It represents a promising diagnostic marker that could be used as an adjunct to tissue biopsy as part of prostate cancer screening.
