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Background: Glutathione S-transferase 1 (GSTP1) inactivation is associated with CpG island promoter hypermethylation in the majority of prostate cancers (PCs). This study assessed whether the level of circulating methylated GSTP1 (mGSTP1) in plasma DNA is associated with chemotherapy response and overall survival (OS). Methods: Plasma samples were collected prospectively from a Phase I exploratory cohort of 75 men with castrate-resistant PC (CRPC) and a Phase II independent validation cohort (n=51). mGSTP1 levels in free DNA were measured using a sensitive methylation-specific PCR assay. Results: The Phase I cohort identified that detectable baseline mGSTP1 DNA was associated with poorer OS (HR, 4.2 95% CI 2.1–8.2; P

Changes in the epigenetic landscape are widespread in neoplasia, with de novo methylation and histone repressive marks commonly enriched in CpG island associated promoter regions. DNA hypermethylation and histone repression correlate with gene silencing, however, the dynamics of this process are still largely unclear. The tumour suppressor gene p16(INK4A) is inactivated in association with CpG island methylation during neoplastic progression in a variety of cancers, including breast cancer. Here, we investigated the temporal progression of DNA methylation and histone remodelling in the p16(INK4A) CpG island in primary human mammary epithelial cell (HMEC) strains during selection, as a model for early breast cancer. Silencing of p16(INK4A) has been previously shown to be necessary before HMECs can escape from selection. Here, we demonstrate that gene silencing occurs prior to de novo methylation and histone remodelling. An increase in DNA methylation was associated with a rapid loss of both histone H3K27 trimethylation and H3K9 acetylation and a gradual gain of H3K9 dimethylation. Interestingly, we found that regional-specific 'seeding' methylation occurs early after post-selection and that the de novo methylation pattern observed in HMECs correlates with the apparent footprint of nucleosomes across the p16(INK4A) CpG island. Our results demonstrate for the first time that p16(INK4A) gene silencing is a precursor to epigenetic suppression and that subsequent de novo methylation initially occurs in nucleosome-free regions across the p16(INK4A) CpG island and this is associated with a dynamic change in histone modifications.

A pilot study was performed to investigate the use of digital PCR (dPCR) to detect minimal residual disease (MRD) in patients with multiple myeloma. dPCR allows greater quantitative specificity in PCR reactions by performing multiple, minute PCR reactions on individual DNA templates.

As new therapies increase the incidence of stringent complete remission (sCR) and overall survival (OS) of patients with multiple myeloma (MM), there is a growing demand for a sufficiently sensitiv...

Glutathione-S-Transferases (GSTs) comprise a family of isoenzymes that provide protection to mammalian cells against electrophilic metabolites of carcinogens and reactive oxygen species. Previous studies have shown that the CpG-rich promoter region of the pi-class gene GSTP1 is methylated at single restriction sites in the majority of prostate cancers. In order to understand the nature of abnormal methylation of the GSTP1 gene in prostate cancer we undertook a detailed analysis of methylation at 131 CpG sites spanning the promoter and body of the gene. Our results show that DNA methylation is not confined to specific CpG sites in the promoter region of the GSTP1 gene but is extensive throughout the CpG island in prostate cancer cells. Furthermore we found that both alleles are abnormally methylated in this region. In normal prostate tissue, the entire CpG island was unmethylated, but extensive methylation was found outside the island in the body of the gene. Loss of GSTP1 expression correlated with DNA methylation of the CpG island in both prostate cancer cell lines and cancer tissues whereas methylation outside the CpG island in normal prostate tissue appeared to have no effect on gene expression.

11 Background: GSTP1 is inactivated and displays aberrant CpG island promoter methylation in the majority of prostate cancers (PCs). The aim of this study was to assess whether changes in methylated glutathione s-transferase 1 (mGSTP1) levels are predictive of response to chemotherapy and overall survival (OS). Methods: Plasma samples were collected prospectively from a phase I exploratory cohort of 75 men with castration-resistant prostate cancer (CRPC) (40 treated with chemotherapy) and a phase II independent validation cohort (n=51). Plasma samples were collected at presentation with CRPC and pre- and post-cycle one of chemotherapy (90% Docetaxel). mGSTP1 levels were measured using a methylation-specific head-loop PCR assay from DNA isolated from either (1) immunomagnetic separation of circulating tumor cells (CTCs) or (2) free plasma DNA. The associations between plasma mGSTP1 levels, PSA response (defined by PCWG1 criteria), and OS were tested using non-parametric tests and survival analyses. Results: The ability to detect mGSTP1 was significantly higher for the plasma free DNA assay compared to DNA from CTCs (p

4603 Background: GSTP1 is inactivated in >98% of all prostate cancers through aberrant DNA methylation. A urinary mGSTP1 assay has been developed as a diagnostic test for localized PC. Serum mGSTP1...