Ten eleven translocation enzymes and 5-hydroxymethylation in mammalian development and cancer.

5-Hydroxymethylcytosine (5hmC) is an oxidative product of 5-methylcytosine (5mC), catalyzed by the ten eleven translocation (TET) family of enzymes. Although 5hmC was discovered several decades ago, it was only after its recent identification in murine brain and stem cell DNA that it has become a major focus of epigenomic research. Part of the reason for this delay is due to the difficulty in detecting both global and locus-specific 5hmC levels.

The MspJI family of modification-dependent restriction endonucleases for epigenetic studies.

MspJI is a novel modification-dependent restriction endonuclease that cleaves at a fixed distance away from the modification site. Here, we present the biochemical characterization of several MspJI homologs, including FspEI, LpnPI, AspBHI, RlaI, and SgrTI. All of the enzymes specifically recognize cytosine C5 modification (methylation or hydroxymethylation) in DNA and cleave at a constant distance (N(12)/N(16)) away from the modified cytosine.

Regulation of expression and activity of DNA (cytosine-5) methyltransferases in mammalian cells.

Three active DNA (cytosine-5) methyltransferases (DNMTs) have been identified in mammalian cells, Dnmt1, Dnmt3a, and Dnmt3b. DNMT1 is primarily a maintenance methyltransferase, as it prefers to methylate hemimethylated DNA during DNA replication and in vitro. DNMT3A and DNMT3B are de novo methyltransferases and show similar activity on unmethylated and hemimethylated DNA.

Opposing roles of Dnmt1 in early- and late-stage murine prostate cancer.

Previous studies have shown that tumor progression in the transgenic adenocarcinoma of mouse prostate (TRAMP) model is characterized by global DNA hypomethylation initiated during early-stage disease and locus-specific DNA hypermethylation occurring predominantly in late-stage disease. Here, we utilized Dnmt1 hypomorphic alleles to examine the role of Dnmt1 in normal prostate development and in prostate cancer in TRAMP. Prostate tissue morphology and differentiation status was normal in Dnmt1 hypomorphic mice, despite global DNA hypomethylation.

Lack of evidence for green tea polyphenols as DNA methylation inhibitors in murine prostate.

Green tea polyphenols (GTP) have been reported to inhibit DNA methylation in cultured cells. Here, we tested whether oral consumption of GTPs affects normal or cancer-specific DNA methylation in vivo, using mice. Wild-type (WT) and transgenic adenocarcinoma of mouse prostate (TRAMP) mice were given 0.

Expression level and DNA methylation status of glutathione-S-transferase genes in normal murine prostate and TRAMP tumors.

Background: Glutathione-S-transferase (Gst) genes are downregulated in human prostate cancer, and GSTP1 silencing is mediated by promoter DNA hypermethylation in this malignancy. We examined Gst gene expression and Gst promoter DNA methylation in normal murine prostates and Transgenic Adenocarcinoma of Mouse Prostate (TRAMP) tumors.

Methods: Primary and metastatic tumors were obtained from TRAMP mice, and normal prostates were obtained from strain-matched WT mice (n = 15/group).

Stage-specific alterations of DNA methyltransferase expression, DNA hypermethylation, and DNA hypomethylation during prostate cancer progression in the transgenic adenocarcinoma of mouse prostate model.

We analyzed DNA methyltransferase (Dnmt) protein expression and DNA methylation patterns during four progressive stages of prostate cancer in the transgenic adenocarcinoma of mouse prostate (TRAMP) model, including prostatic intraepithelial neoplasia, well-differentiated tumors, early poorly differentiated tumors, and late poorly differentiated tumors. Dnmt1, Dnmt3a, and Dnmt3b protein expression were increased in all stages; however, after normalization to cyclin A to account for cell cycle regulation, Dnmt proteins remained overexpressed in prostatic intraepithelial neoplasia and well-differentiated tumors, but not in poorly differentiated tumors. Restriction landmark genomic scanning analysis of locus-specific methylation revealed a high incidence of hypermethylation only in poorly differentiated (early and late) tumors.