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Choi, Kim, Kim, Koh, Kim, and Lee: Helicobacter pylori Eradication Modulates Aberrant CpG Island Hypermethylation in Gastric Carcinogenesis
Original Article

Korean J Gastroenterol 2016;68(5):253-259.

Published online: 4 October 2016

DOI: https://doi.org/10.4166/kjg.2016.68.5.253

Helicobacter pylori Eradication Modulates Aberrant CpG Island Hypermethylation in Gastric Carcinogenesis

Jeongmin Choi, Sang Gyun Kim1, Byeong Gwan Kim2, Seong-Joon Koh2, Ji Won Kim2, Kook Lae Lee2

Department of Internal Medicine, Inje University Sanggye Paik Hospital, Inje University College of Medicine, Seoul, Korea

1Department of Internal Medicine and Liver Research Institute, Seoul National University College of Medicine, Seoul, Korea

2Department of Internal Medicine, SMG-SNU Boramae Medical Center, Seoul, Korea

Correspondence to: Sang Gyun Kim, Department of Internal Medicine and Liver Research Institute, Seoul National University College of Medicine, 101 Daehak-ro, Jongno-gu, Seoul 03080, Korea. Tel: +82-2-740-8112, Fax: +82-2-743-6701, E-mail: harley@snu.ac.kr

Received 8 September 2016       Revised 13 October 2016       Accepted 24 October 2016

Copyright © 2016 Korean Ophthalmological Society

This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/4.0/) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Background/Aims

Helicobacter pylori infection induces aberrant DNA methylation in gastric mucosa. We evaluated the long-term effect of H. pylori eradication on promotor CpG island hypermethylation in gastric carcinogenesis.

Methods

H. pylori-positive patients with gastric adenoma or early gastric cancer who underwent endoscopic resection were enrolled. According to H. pylori eradication after endoscopic resection, the participants were randomly assigned to H. pylori eradication or non-eradication group. H. pylori-negative gastric mucosa from normal participants provided the normal control. CpG island hypermethylation of tumor-related genes (p16, CDH1, and RUNX-3) was evaluated by quantitative MethyLight assay in non-tumorous gastric mucosa. The gene methylation rate and median values of hypermethylation were compared after one year by H. pylori status.

Results

In H. pylori-positive patients, hypermethylation of p16 was found in 80.6%, of CDH1 in 80.6%, and of RUNX-3 in 48.4%. This is significantly higher than normal control (p16, 10%; CDH1, 44%; RUNX-3, 16%) (p<0.05). In the H. pylori eradication group, methylation rates of p16 and CDH1 decreased in 58.1% and 61.3% of the patients, and the median values of hyper-methylation were significantly lower at one year compared with the non-eradication group. However, RUNX-3 hypermethylation did not differ significantly at one year after H. pylori eradication. The non-eradication group hypermethylation did not change after one year.

Conclusions

H. pylori infection was associated with promotor hypermethylation of genes in gastric carcinogenesis, and H. pylori eradication might reverse p16 and CDH1 hypermethylation.

Keywords: Helicobacter pylori, CpG hypermethylation, p16, CDH1, Carcinogenesis

References

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Fig. 1.
Changes in quantitative value of MethyLight assay (percentage of methylated reference, PMR) of p16, RUNX-3 and CDH1 at baseline and after one year in the Helicobacter pylori eradication group. PMR value in p16 and CDH1 were significantly reduced one year after eradication.
kjg-68-253f1.tif
Table 1.
Clinicopathological Characteristics among Groups
Characteristic Group
Helicobacer pylori eradication Non-eradication p-value a Normal control
Gender     1.00  
 Male 21 (67.7) 22 (64.7)   11 (61.1)
 Female 10 (32.3) 12 (35.3)   7 (38.9)
Age (yr) 60.0 (50.0–66.0) 59.5 (54.7–66.0) 0.68 58.5 (50.0–67.5)
Gastric atrophy     0.42  
 Absent 5 (16.1) 2 (5.9)   7 (38.9)
 Mild 6 (19.4) 6 (17.6)   9 (50.0)
 Moderate 11 (35.5) 10 (29.4)   2 (11.1)
 Marked 3 (9.7) 6 (17.6)   0 (0)
 NA 6 (19.4) 10 (29.4)   0 (0)
Intestinal metaplasia     1.00  
 Absent 1 (3.2) 2 (5.9)   11 (61.1)
 Mild 9 (29.0) 8 (23.5)   3 (16.7)
 Moderate 13 (41.9) 19 (55.9)   4 (22.2)
 Marked 8 (25.8) 5 (14.7)   0 (0)
Gastric atrophy or IM     0.97  
 Absent 1 (3.2) 1 (2.9)   7 (38.9)
 Mild 9 (29.0) 9 (26.5)   9 (50.0)
 Moderate 12 (38.7) 15 (44.1)   2 (11.1)
 Marked 9 (29.0) 9 (26.5)   0 (0)
H. pylori density     0.75 0 (0)
 Mild 10 (32.3) 14 (41.2)    
 Moderate 14 (45.2) 13 (38.2)    
 Marked 7 (22.6) 7 (20.6)    
Neutrophilic inflammation     0.25  
 Absent 1 (3.2) 0 (0)    
 Mild 0 (0) 3 (8.8)    
 Moderate 25 (80.6) 27 (79.4)    
 Marked 5 (16.1) 4 (11.8)    
Mononuclear inflammation     0.43  
 Absent 0 (0) 0 (0)    
 Mild 0 (0) 0 (0)    
 Moderate 20 (64.5) 25 (73.5)    
 Marked 11 (35.5) 9 (26.5)    
Histology     0.55  
 Low-grade dysplasia 12 (38.7) 10 (29.4)   0 (0)
 High-grade dysplasia 4 (12.9) 3 (8.8)   0 (0)
 Adenocarcinoma 15 (48.4) 21 (61.8)   0 (0)
  Well differentiated 5 (16.1) 11 (32.4)    
  Moderately differentiated 7 (22.6) 6 (17.6)    
  Poorly differentiated 2 (6.5) 1 (2.9)    
  Signet ring cell 1 (3.2) 3 (8.8)    
 Total 31 (100) 34 (100) 　 18 (100)

Values are presented as n (%) or median (interquartile range).

NA, not available; IM, intestinal metaplasia.

a Comparison between H. pylori eradication and non-eradication group.

Table 2.
Promotor Gene Methylation Rates and Median Methylation Values at Baseline and One Year among Groups
Variable Group
Helicobacter pylori eradication Non-eradication Normal control
Baseline 1 yr p-value a Baseline 1 yr p-value b Baseline p-value c
Methylated gene (%)
 P16 80.6 58.1 1.00 71.1 84.2 0.33 10.0 0.01
 RUNX-3 48.4 67.7 0.25 55.3 65.8 0.05 16.0 0.03
 CDH1 80.6 61.3 1.00 97.4 100 1.00 44.0 0.01
Median methylation value (PMR)
 P16 11.7 5.7 0.01 12.9 17.8 0.25 3.4 0.01
 RUNX-3 2.2 9.8 0.41 30.5 50.4 0.18 13.9 0.01
 CDH1 47.9 7.0 0.01 67.7 76.6 0.24 5.3 0.01
Patient (total, n) 31 　 　 34 　 　 18 　

PMR, percentage of methylated reference.

a Comparison of methylation between baseline and one year after in the H. pylori eradication group.

b Comparison of methylation between baseline and one year after in the non-eradication group.

c Comparison of baseline methylation in the eradication group with normal control.

Table 3.
Promotor Gene Methylation Rates and Median Methylation Values at Baseline and One Year according to Gastric Adenoma or Early Gastric Cancer
Variable Helicobacter pylori eradication Non-eradication
Adenoma Cancer Adenoma Cancer
Baseline 1 yr p-value Baseline e 1 yr p-value Baseline 1 yr p-value Baseline 1 yr p-value
Methylated gene (%)
 P16 75.0 68.8 1.00 86.7 46.7 0.07 61.5 69.2 1.00 76.2 95.2 0.13
 RUNX-3 62.5 75.0 0.73 33.3 60.0 0.13 61.5 69.2 1.00 52.4 71.4 0.29
 CDH1 81.3 56.3 0.29 80.0 66.7 0.69 100 100 1.00 95.2 100 1.00
Median methylation value (PMR)
 P16 9.7 5.7 0.20 15.3 3.2 0.02 5.24 10.4 0.55 6.92 14.4 0.06
 RUNX-3 19.1 15.9 0.61 0.01 9.6 0.96 11.3 22.2 0.02 9.1 25.4 0.59
 CDH1 49.7 2.4 0.01 28.9 9.7 0.04 44.0 99.7 0.04 78.1 78.3 0.59
Patient (n) 16 　 　 15 　 　 13 　 　 21 　 　

PMR, percentage of methylated reference.

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