Age-Related Methylation Patterning of Housekeeping Genes and Tissue-Specific Genes is Distinct Between the Stomach Antrum and Body

Abstract

Aim: The methylation-variable sites around CpG islands are frequently overmethylated in Helicobacter pylori-infected stomachs. Age-related patterns of the overmethylation changes were compared between the fast-growing antrum cells and the slow-growing body cells. Materials & methods: A total of 316 H. pylori-positive tissues and 380 H. pylori-negative tissues were obtained by endoscopic biopsy. The methylation-variable sites of ten housekeeping genes and nine tissue-specific genes were semiquantitatively analyzed, based on the ten-level classification of methylation-specific PCR intensity. The overmethylated genes were scored when their methylation levels were higher than an intermediate level of each gene common in the H. pylori-negative mucosa. Results: The age-dependent methylation level of the inactive APC gene observed similarly in the antrum and the body was used as an age standard of methylation variation in a biopsy tissue. The overmethylation of housekeeping genes and stomach-specific genes rapidly increased to a high plateau frequency in the young-aged APC methylation cases (mean age: 43 years) in the H. pylori-positive antrum. In the H. pylori-positive body, most of the overmethylated housekeeping genes slowly increased to a peak frequency in the middle-aged APC methylation cases (mean age: 53 years). The housekeeping gene pairs showed high correlations (Spearman‘s correlation coefficient > 0.4) in both the antrum and the body. Conclusion: The overmethylation of housekeeping genes rapidly and slowly increased to a high frequency in concordance with a rapid and slow growth of epithelial cells in the H. pylori-infected stomach.

KEYWORDS::

• DNA methylation
• Helicobacter pylori
• housekeeping gene
• retroelement

Financial & competing interests disclosure

This work was supported by the Catholic Medical Center Research Foundation made in the program year of 2011 (5-2011-B0001-00029). The authors have no other relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript apart from those disclosed.

No writing assistance was utilized in the production of this manuscript.

Ethical conduct of research

The authors state that they have obtained appropriate institutional review board approval or have followed the principles outlined in the Declaration of Helsinki for all human or animal experimental investigations. In addition, for investigations involving human subjects, informed consent has been obtained from the participants involved.

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Funding

This work was supported by the Catholic Medical Center Research Foundation made in the program year of 2011 (5-2011-B0001-00029). The authors have no other relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript apart from those disclosed.