Ray-Whay Chiu Yen

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Inactivation of tumour suppressor genes is central to the development of all common forms of human cancer. This inactivation often results from epigenetic silencing associated with hypermethylation rather than intragenic mutations. In human cells, the mechanisms underlying locus-specific or global methylation patterns remain unclear. The prototypic DNA(More)
Reversal of promoter DNA hypermethylation and associated gene silencing is an attractive cancer therapy approach. The DNA methylation inhibitors decitabine and azacitidine are efficacious for hematological neoplasms at lower, less toxic, doses. Experimentally, high doses induce rapid DNA damage and cytotoxicity, which do not explain the prolonged time to(More)
Epigenetic therapy is emerging as a potential therapy for solid tumors. To investigate its mechanism of action, we performed integrative expression and methylation analysis of 63 cancer cell lines (breast, colorectal, and ovarian) after treatment with the DNA methyltransferase inhibitor 5-azacitidine (AZA). Gene Set Enrichment Analysis demonstrated(More)
The role of the primary mammalian DNA methyltransferase, DNMT1, in maintaining CpG island methylation in human colon cancer cells has recently been questioned. This controversy has arisen from discrepancies between genetic knockout and RNA interference-mediated knockdown studies. Here, we re-examined the RNA interference-based approach and found that(More)
Innovative therapies are needed for advanced Non-Small Cell Lung Cancer (NSCLC). We have undertaken a genomics based, hypothesis driving, approach to query an emerging potential that epigenetic therapy may sensitize to immune checkpoint therapy targeting PD-L1/PD-1 interaction. NSCLC cell lines were treated with the DNA hypomethylating agent azacytidine(More)
A major obstacle toward understanding how patterns of abnormal mammalian cytosine DNA methylation are established is the difficulty in quantitating the de novo methylation activities of DNA methyltransferases (DNMT) thought to catalyze these reactions. Here, we describe a novel method, using native human CpG island substrates from genes that frequently(More)
The role of DNA methyltransferase 1, DNMT1, in human cancer cells has recently been contested. In this setting, DNMT1's function as the sole maintenance methyltransferase was based on the assumption that its biological activity is identical to the mouse homologue. However, the application of recent technological advances, including gene targeting and siRNA(More)
TET proteins, by converting 5-methylcytosine (5mC) to 5-hydroxymethylcytosine (5hmC), are hypothesized, but not directly shown, to protect promoter CpG islands (CGIs) against abnormal DNA methylation (DNAm) in cancer. We define such a protective role linked to DNA damage from oxidative stress (OS) known to induce this abnormality. TET2 removes aberrant DNAm(More)
Reversing DNA methylation abnormalities and associated gene silencing, through inhibiting DNA methyltransferases (DNMTs) is an important potential cancer therapy paradigm. Maximizing this potential requires defining precisely how these enzymes maintain genome-wide, cancer-specific DNA methylation. To date, there is incomplete understanding of precisely how(More)
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