RUNX3 methylation and expression associated with advanced precancerous gastric lesions in a Chinese population.

Runt-related transcription factor 3 (RUNX3) is a tumor suppressor of gastric cancer. Our study aimed to investigate the correlation of RUNX3 methylation, expression and the risk of advanced gastric lesions, based on a high-risk population in Linqu County, Shandong Province, China. Methylation status of RUNX3 was determined by methylation-specific polymerase chain reaction, and expression was detected by immunohistochemical analysis in 1113 subjects with different gastric lesions. Results showed that the frequency of RUNX3 methylation was significantly increased in subjects with advanced gastric lesions. The odds ratios (ORs) were 2.09 [95% confidence interval (CI): 1.49-2.94] for intestinal metaplasia (IM), 3.22 (95% CI: 2.33-4.47) for indefinite dysplasia (Ind DYS) and 2.03 (95% CI: 1.23-3.37) for dysplasia (DYS) compared with superficial gastritis/chronic atrophic gastritis. Stratified analysis indicated that the frequency of RUNX3 methylation was higher in subjects with Helicobacter pylori infection (OR, 2.74; 95% CI: 2.00-3.76). Moreover, there was a reverse grade-response relationship between the level of RUNX3 expression and risk of gastric lesions. Among subjects with mild, moderate or heavy expression, the risk was decreased by 41, 59 or 80% for IM (P(trend) < 0.0001); 40, 64 or 74% for Ind DYS (P(trend) < 0.0001) and 28, 59 or 51% for DYS (P(trend) = 0.045), respectively. Furthermore, RUNX3 expression was negatively associated with increased frequency of RUNX3 methylation (OR, 0.76; 95% CI: 0.59-0.98). These findings suggest that RUNX3 may play important roles in the development of advanced gastric lesions.

Methylation of GATA-4 and GATA-5 and development of sporadic gastric carcinomas.

AIM: To understand the implication of GATA-4 and GATA-5 methylation in gastric carcinogenesis. METHODS: Methylation status of GATA-4 and GATA-5 CpG islands in human gastric mucosa samples, including normal gastric biopsies from 45 outpatients, gastric dysplasia [low-grade gastric intraepithelial neoplasia (GIN), n = 30; indefinite, n = 77], and 80 paired sporadic gastric carcinomas (SGC) as well as the adjacent non-neoplastic gastric tissues was analyzed by methylation specific polymerase chain reaction (MSP) and confirmed by denatured high performance liquid chromatography (DHPLC). Immunohistochemical staining was used to detect protein expression. The correlation between GATA-4 and GATA-5 methylation and clinicopathological characteristics of patients including Helicobacter pylori (H. pylori) infection was analyzed. RESULTS: GATA-4 and GATA-5 methylation was frequently observed in SGCs (53.8% and 61.3%, respectively) and their corresponding normal tissues (41.3% and 46.3%) by MSP. The result of MSP was consistent with that of DHPLC. Loss of both GATA-4 and GATA-5 proteins was associated with their methylation in SGCs (P = 0.01). Moreover, a high frequency of GATA-4 and GATA-5 methylation was found in both gastric low-grade GIN (57.1% and 69.0%) and indefinite for dysplasia (42.9% and 46.7%), respectively. However, GATA-4 and GATA-5 methylation was detected only in 4/32 (12.5%) and 3/39 (7.7%) of normal gastric biopsies. GATA-4 methylation in both normal gastric mucosa and low-grade GIN was also significantly associated with H. pylori infection (P = 0.023 and 0.027, two-sides). CONCLUSION: Epigenetic inactivation of GATA-4 (and GATA-5) by methylation of CpG islands is an early frequent event during gastric carcinogenesis and is significantly correlated with H. pylori infection.

Promoter methylation of p16 associated with Helicobacter pylori infection in precancerous gastric lesions: a population-based study.

To investigate the relationship between p16 methylation and Helicobacter pylori infection in precancerous gastric lesions, a population-based study was conducted in Linqu County, a high-risk area of gastric cancer in China. Methylation status of p16 was evaluated by methylation-specific polymerase chain reaction in 920 subjects with precancerous gastric lesions. H. pylori status was determined by 13C-urea breath test and the density of H. pylori in biopsy specimens used for detecting methylation status was assessed by the modified Giemsa stain. The frequency of p16 methylation was significantly higher in subjects with H. pylori positive than those with H. pylori negative in each category of gastric lesion (p<0.001, respectively). Compared with H. pylori negative, the odds ratios (ORs) of p16 methylation were markedly elevated in subjects with H. pylori positive for superficial gastritis (OR, 9.45; 95% confidence interval [CI]: 2.94-30.41), chronic atrophic gastritis (OR, 15.92; 95%CI: 7.60-33.36), intestinal metaplasia (OR, 4.46; 95%CI: 2.44-8.13), indefinite dysplasia (OR, 3.67; 95%CI: 1.90-7.10), and dysplasia (OR, 2.48; 95%CI: 1.02-5.99). Moreover, the frequencies of p16 methylation increased steadily with the severity of H. pylori density in gastric mucosa. Compared with H. pylori negative, the OR of p16 methylation was 1.02-16.13 times higher in subjects with mild H. pylori infection, and 2.69-38.73 times higher in those with moderate/severe infection, respectively. Our findings indicate that p16 methylation was significantly associated with H. pylori infection in precancerous gastric lesions, suggesting that H. pylori infection could potently induce methylation of p16 CpG island.

[The correlative analysis of indefinite dysplasia and dysplasia, and its p16 methylation in human gastric mucosa with Helicobacter pylori infection].

OBJECTIVE: To compare the CpG island methylation status of p16 in subjects with gastric indefinite dysplasia or dysplasia, and investigate its association with exposure factors. METHODS: Methylation status of p16 was determined by methylation specific PCR method and denaturing high-performance liquid chromatography analysis in 223 indefinite dysplasia and 130 dysplasia from Linqu County in Shandong Province, an area with high GC mortality rates. Multivariable analysis was used to analyze the relationship between p16 methylation and age, gender, cigarette smoking, alcohol drinking, and Helicobacter pylori infection. RESULTS: The methylation frequency of p16 in indefinite dysplasia was not significantly different from that of dysplasia (28.3% vs 24.6%, P=0.46). No significant association was found between p16 methylation and age, gender, cigarette smoking, and alcohol drinking. In dysplasia, the association between p16 methylation and Helicobacter pylori infection was close to the statistical significance by univariate analysis that the relative risk of p16 methylation of the infected subjects(n=93) is higher than that of the uninfected subjects (n=37)(OR=2.62, 95% CI: 0.92 to 7.43, P=0.07).But by multivariate analysis, there was no association between them(P=0.11). CONCLUSION: The frequency of p16 methylation in gastric mucosa of indefinite dysplasia was similar to that of dysplasia. p16 methylation status was not associated with age, but might be significantly associated with Helicobacter pylori infection.