BACKGROUND: Epigenetic alteration of gene expression is a common event in human cancer. DNA methylation is a well-known epigenetic process, but verifying the exact nature of epigenetic changes associated with cancer remains difficult. METHODS: We profiled the methylome of human gastric cancer tissue at 50-bp resolution using a methylated DNA enrichment technique (methylated CpG island recovery assay) in combination with a genome analyzer and a new normalization algorithm. RESULTS: We were able to gain a comprehensive view of promoters with various CpG densities, including CpG Islands (CGIs), transcript bodies, and various repeat classes. We found that gastric cancer was associated with hypermethylation of 5' CGIs and the 5'-end of coding exons as well as hypomethylation of repeat elements, such as short interspersed nuclear elements and the composite element SVA. Hypermethylation of 5' CGIs was significantly correlated with downregulation of associated genes, such as those in the HOX and histone gene families. We also discovered long-range epigenetic silencing (LRES) regions in gastric cancer tissue and identified several hypermethylated genes (MDM2, DYRK2, and LYZ) within these regions. The methylation status of CGIs and gene annotation elements in metastatic lymph nodes was intermediate between normal and cancerous tissue, indicating that methylation of specific genes is gradually increased in cancerous tissue. CONCLUSIONS: Our findings will provide valuable data for future analysis of CpG methylation patterns, useful markers for the diagnosis of stomach cancer, as well as a new analysis method for clinical epigenomics investigations.
BACKGROUND: Epigenetic alteration of gene expression is a common event in humancancer. DNA methylation is a well-known epigenetic process, but verifying the exact nature of epigenetic changes associated with cancer remains difficult. METHODS: We profiled the methylome of humangastric cancer tissue at 50-bp resolution using a methylated DNA enrichment technique (methylated CpG island recovery assay) in combination with a genome analyzer and a new normalization algorithm. RESULTS: We were able to gain a comprehensive view of promoters with various CpG densities, including CpG Islands (CGIs), transcript bodies, and various repeat classes. We found that gastric cancer was associated with hypermethylation of 5' CGIs and the 5'-end of coding exons as well as hypomethylation of repeat elements, such as short interspersed nuclear elements and the composite element SVA. Hypermethylation of 5' CGIs was significantly correlated with downregulation of associated genes, such as those in the HOX and histone gene families. We also discovered long-range epigenetic silencing (LRES) regions in gastric cancer tissue and identified several hypermethylated genes (MDM2, DYRK2, and LYZ) within these regions. The methylation status of CGIs and gene annotation elements in metastatic lymph nodes was intermediate between normal and cancerous tissue, indicating that methylation of specific genes is gradually increased in cancerous tissue. CONCLUSIONS: Our findings will provide valuable data for future analysis of CpG methylation patterns, useful markers for the diagnosis of stomach cancer, as well as a new analysis method for clinical epigenomics investigations.
Authors: M Aoki; K Yamamoto; H Noshiro; K Sakai; J Yokota; T Kohno; T Tokino; S Ishida; S Ohyama; I Ninomiya; K Uesaka; M Kitajima; S Shimada; S Matsuno; M Yano; M Hiratsuka; H Sugimura; F Itoh; T Minamoto; Y Maehara; S Takenoshita; T Aikou; H Katai; K Yoshimura; T Takahashi; K Akagi; M Sairenji; Y Yamamura; T Sasazuki Journal: J Med Genet Date: 2005-01 Impact factor: 6.318
Authors: Michael Weber; Jonathan J Davies; David Wittig; Edward J Oakeley; Michael Haase; Wan L Lam; Dirk Schübeler Journal: Nat Genet Date: 2005-07-10 Impact factor: 38.330
Authors: P Guilford; J Hopkins; J Harraway; M McLeod; N McLeod; P Harawira; H Taite; R Scoular; A Miller; A E Reeve Journal: Nature Date: 1998-03-26 Impact factor: 49.962
Authors: Wen Quan Jonathan Goh; Ghim Siong Ow; Vladimir A Kuznetsov; Shirly Chong; Yoon Pin Lim Journal: Am J Transl Res Date: 2015-06-15 Impact factor: 4.060