Associations between a PTPN11 polymorphism and gastric atrophy--opposite in Uzbekistan to that in Japan.

Src homology 2 domain-containing protein tyrosine phosphatase-2 (SHP-2) of gastric epithelial cells interacts with cagA from Helicobacter pylori (H. pylori). Our previous studies found the AA genotype of a G/A single nucleotide polymorphism at intron 3 (rs2301756) of PTPN11 gene, which encodes SHP-2, to be associated with a lower risk of gastric atrophy. The present study aimed to examine the association with gastric atrophy among the subjects of a case-control study of peptic ulcer disease (PUD) conducted in the Uzbek Republic. Cases were 95 patients (61 males and 34 females) with PUD aged 16 to 85 years. Controls were 102 hospital volunteers (42 males and 60 females) including 42 patients with miscellaneous diseases, aged 15 to 75 years. Gastric atrophy was evaluated with serum pepsinogens (PG1<70 ng/ml and PG1/PG2<3). Polymorphisms of PTPN11 at intron 3 (rs2301756) and intron10 (rs12229892) were genotyped with PCR with confronting two-pair primers (PCR-CTPP). Anti-cagA IgG antibody was detected in 93.7% of cases and 77.5% in controls. Gastric atrophy was observed in 24.2% of the PUD patients and 33.3% in the controls. The A allele at intron 3 was completely linked to the G allele at intron 10. The age, sex, and group (cases and controls) adjusted odds ratio of gastric atrophy was 0.18 (95% confidence interval, 0.04-0.86) for intron 3 GG genotype relative to AA genotype. Since the finding was opposite to that among Japanese, the H. pylori strains and/or lifestyle in Uzbekistan might modify the association.

No association of an SDHC gene polymorphism with gastric cancer.

It is widely reported that reactive oxygen species (ROS) cause apotosis and carcinogenesis. Marked infiltration of activated leukocyte and enhanced production of ROS appear to occur in the gastric mucosa infected with Helicobacter pylori (H. pylori). The previous studies reported that the mutation of the succinate dehydrogenase subunit C (SDHC) gene caused the increase in superoxide anion (O(2)(-)) and oxidative stress. To extend these findings, we epidemiologically investigated the association of a SDHC polymorphism at 3'-untranslated region of exon 6 (JST173800) with H. pylori infection, gastric atrophy and gastric cancer risk in Japan. The subjects consisted of 454 health checkup examinees without a history of cancer and 202 gastric cancer patients. The SDHC polymorphism was not associated with H. pylori infection seropositivity, gastric atrophy, and cancer risk in this study. Although the polymorphism at the 3'-untranslated region could be hypothesized to be functional, this study did not demonstrate any significant association of the SDHC gene polymorphism with gastric atrophy and cancer.

The ACE gene polymorphism is associated with the incidence of gastric cancer among H. pylori seropositive subjects with atrophic gastritis.

Studies of the angiotensin converting enzyme (ACE) I/D polymorphism have provided evidence that the D/D genotype is associated with gastric tumor progression and numbers of lymph node metastases, but not with the overall risk of gastric cancer. The highest levels of circulating and tissue ACE activity were found in carriers of the D/D genotype. Here, we further investigated the association using 454 Japanese subjects undergoing a health checkup and 202 gastric cancer patients. The ACE polymorphism was not found to be linked with H. pylori seropositivity or gastric atrophy. However, among H. pylori seropositive subjects with atrophy, those with the I/D genotype had an increased risk of gastric cancer (OR=1.59; 95% CI, 1.02-2.48). We also established that the polymorphism did not lower the age at diagnosis of gastric cancer. Confirmation of the association between ACE polymorphisms and development of gastric cancer requires much larger studies, and the biological role also needs to be fully elucidated.

A pilot study on genotype announcement to induce smoking cessation by Japanese smokers.

BACKGROUND: Genotype announcements related to susceptibility to hazardous effects of smoking may be effective to induce smoking cessation. METHODS: Subjects were municipal government employees, 63 young smokers employed in the previous year and 59 smokers with more than 45 pack-years, who were invited to educational sessions against smoking held in December 2003 and February 2004, respectively. In the session, those who wished genetic susceptibility tests (GSTM1, GSTT1, and NQO1 C609T) were enrolled in the study. The smoking habit was ascertained three times: at the session, one month later, just before the genotype announcement, and at the follow-up three months after the announcement. RESULTS: Fifty eight (92.1%) and 49 (83.1%) smokers participated in the study, respectively. One out of 58 smokers was not a habitual smoker, so was not included in the analysis. The smoking cessation rates were 15.8% (9 participants) and 6.1% (3 participants) just before the genotype announcement, and 7.0% (4 participants) and 10.2% (5 participants) at the follow-up, respectively. All subjects were satisfied with the genotype testing except for two who rather regretted participating, but one of whom actually quit smoking. CONCLUSION: The present pilot study without controls indicated that the effects of genotype announcements in this framework on smoking cessation were less than might have been expected. The temporary effect of the session on younger smokers may have been due to the participation per se. The potential effects of genotype announcements for heavy smokers should now be examined in studies with adequate controls.

Helicobacter pylori eradication as a preventive tool against gastric cancer.

Helicobacter pylori (H. pylori), which increases the risk of gastric diseases, including digestive ulcers and gastric cancer, is highly prevalent in Asian countries. There is no doubt that eradication of the bacterium is effective as a treatment of digestive ulcer, but eradication aiming to reduce the gastric cancer risk is still controversial. Observational studies in Japan demonstrated that the eradication decreased the gastric cancer risk among 132 stomach cancer patients undergoing endoscopical resection (65 treated with omeprazol and antibiotics and 67 untreated). In Columbia, 976 participants were randomized into eight groups in a three-treatment factorial design including H. pylori eradication, resulting in significant regression in the H. pylori eradication group. A recent randomized study in China also showed a significant reduction of gastric cancer risk among those without any gastric atrophy, intestinal metaplasia, and dysplasia. Efficacy of eradication may vary in extent among countries with different incidence rates of gastric cancer. Since the lifetime cumulative risk (0 to 84 years old) of gastric cancer in Japan is reported to be 12.7% for males and 4.8% for females (Inoue and Tominaga, 2003), the corresponding values for H. pylori infected Japanese can be estimated at 21.2% in males and 8.0% in females under the assumptions that the relative risk for infected relative to uninfected is 5 and the proportion of those infected is 0.5. Both the fact that not all individuals are infected among those exposed and the knowledge that only a small percentage of individuals infected with the bacterium develop gastric cancer, indicate the importance of gene-environment interactions. Studies on such interactions should provide useful information for anti-H. pylori preventive strategies.