Role of glutathione-S-transferase P1 hypermethylation in molecular detection of prostate cancer

DNA Framework-Supported Electrochemical Analysis of DNA Methylation for Prostate Cancers

Epigenetic alterations hold great promise as biomarkers for early stage cancer diagnosis. Nevertheless, direct identification of rare methylated DNA in the genome remains challenging. Here, we report an ultrasensitive framework nucleic acid-based electrochemical sensor for quantitative and highly selective analysis of DNA methylation. Notably, we can detect 160 fg of methylated DNA in million-fold unmethylated DNA samples using this electrochemical methylation-specific polymerase chain reaction (E-MSP) method. The high sensitivity of E-MSP enables one-step detection of low-abundance methylation at two different genes in patient serum samples. By using a combination test with two methylation alterations, we achieve high accuracy and sensitivity for reliable differentiation of prostate cancer and benign prostate hypertrophy (BPH). This new method sheds new light on translational use in early cancer diagnosis and in monitoring patients' responses to therapeutic agents.

Dual glutathione-S-transferase-θ1 and -μ1 gene deletions determine imatinib failure in chronic myeloid leukemia

Approximately 40% of patients with chronic myeloid leukemia (CML) receiving imatinib fail treatment. There is an increased risk of CML in subjects with (i) deletions of genes encoding glutathione-S-transferase (GST)-θ1 (GSTT1) and -μ1, (GSTM1) and (ii) the GST-π1 (GSTP1) single-nucleotide polymorphism (SNP) Ile105Val (GSTP1*B; rs1695); however, their effects on imatinib treatment outcome are not known. Here, we assess the role of these GSTs in relation to imatinib treatment outcome in 193 CML patients. Deletion of GSTT1 alone, or in combination with deletion of the GSTM1 gene, significantly increased the likelihood of imatinib failure (P = 0.021 and P < 0.001, respectively). The GSTP1*B SNP was not associated with time to imatinib failure. Losses of the GSTT1 and GSTM1 genes are therefore important determinants of imatinib failure in CML. Screening for GSTT1 and GSTM1 gene deletions during diagnosis may identify patients who may be better treated using an alternative therapy.

DNA methylation and cancer diagnosis

DNA methylation is a major epigenetic modification that is strongly involved in the physiological control of genome expression. DNA methylation patterns are largely modified in cancer cells and can therefore be used to distinguish cancer cells from normal tissues. This review describes the main technologies available for the detection and the discovery of aberrantly methylated DNA patterns. It also presents the different sources of biological samples suitable for DNA methylation studies. We discuss the interest and perspectives on the use of DNA methylation measurements for cancer diagnosis through examples of methylated genes commonly documented in the literature. The discussion leads to our consideration for why DNA methylation is not commonly used in clinical practice through an examination of the main requirements that constitute a reliable biomarker. Finally, we describe the main DNA methylation inhibitors currently used in clinical trials and those that exhibit promising results.

Sensitive and selective amplification of methylated DNA sequences using helper-dependent chain reaction in combination with a methylation-dependent restriction enzymes

We have developed a novel technique for specific amplification of rare methylated DNA fragments in a high background of unmethylated sequences that avoids the need of bisulphite conversion. The methylation-dependent restriction enzyme GlaI is used to selectively cut methylated DNA. Then targeted fragments are tagged using specially designed 'helper' oligonucleotides that are also used to maintain selection in subsequent amplification cycles in a process called 'helper-dependent chain reaction'. The process uses disabled primers called 'drivers' that can only prime on each cycle if the helpers recognize specific sequences within the target amplicon. In this way, selection for the sequence of interest is maintained throughout the amplification, preventing amplification of unwanted sequences. Here we show how the method can be applied to methylated Septin 9, a promising biomarker for early diagnosis of colorectal cancer. The GlaI digestion and subsequent amplification can all be done in a single tube. A detection sensitivity of 0.1% methylated DNA in a background of unmethylated DNA was achieved, which was similar to the well-established Heavy Methyl method that requires bisulphite-treated DNA.

Epigenetic-dependent regulation of drug transport and metabolism: an update

The pharmacokinetics of a drug are subject to large interindividual variability, which can result in lack of response or adverse drug reactions. In addition to genetic polymorphisms and drug interactions, key genes involved in the metabolism and transport of drugs are demonstrated to have epigenetic influences that can potentially affect interindividual variability in drug response. Emerging studies have focused on the importance of DNA methylation for ADME gene expression and for drug action and resistance, particularly in cancer. However, the epigenetic and ncRNA-dependent regulation of these genes, as well as the pharmacological consequences, is in need of greater attention. In the current review we provide an update of epigenetic and ncRNA-dependent regulation of ADME genes.

DNA methylation and soy phytoestrogens: quantitative study in DU-145 and PC-3 human prostate cancer cell lines

AIM

DNA hypermethylation is an epigenetic mechanism which induces silencing of tumor-suppressor genes in prostate cancer. Many studies have reported that specific components of food plants like soy phytoestrogens may have protective effects against prostate carcinogenesis or progression. Genistein and daidzein, the major phytoestrogens, have been reported to have the ability to reverse DNA hypermethylation in cancer cell lines. The aim of this study was to investigate the potential demethylating effects of these two soy compounds on BRCA1, GSTP1, EPHB2 and BRCA2 promoter genes.

METHODS & MATERIALS

Prostate cell lines DU-145 and PC-3 were treated with genistein 40 µM, daidzein 110 µM, budesonide (methylating agent) 2 µM and 5-azacytidine (demethylating agent) 2 µM. In these two human prostate cancer cell lines we performed methylation quantification by using Methyl Profiler DNA methylation analysis. This technique is based on a methylation-specific digestion followed by quantitative PCR. We analyzed the corresponding protein expression by western blotting.

RESULTS

Soy phytoestrogens induced a demethylation of all promoter regions studied except for BRCA2, which is not methylated in control cell lines. An increase in their protein expression was also demonstrated by western blot analysis and corroborated the potential demethylating effect of soy phytoestrogens.

CONCLUSION

This study showed that the soy phytoestrogens, genistein and daidzein, induce a decrease of methylation of BRCA1, GSTP1 and EPHB2 promoters. Therefore, soy phytoestrogens may have a protective effect on prostate cancer. However, more studies are needed in order to understand the mechanism by which genistein and daidzein have an inhibiting action on DNA methylation.