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.

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.

Multiplex PCR with confronting two-pair primers for CYP1A1 Ile462Val, GSTM1, GSTT1, and NQO1 C609T.

Polymerase chain reaction with confronting two-pair primers (PCR-CTPP) is an effective genotyping method for single nucleotide polymorphisms (SNPs) in aspects of reducing time and costs for analysis. So far we have established PCR-CTPP conditions for tens of SNPs, including a triplex genotyping (Kawase et al., 2003). In the present study we report a quadruplex PCR-CTPP to genotype simultaneously four functional polymorphisms of carcinogen-metabolizing enzymes, CYP1A1 Ile462Val, GSTM1 null, GSTT1 null and NQO1 C609T, which were reported that they have significant associations with smoking-related cancers. We applied this method for 475 health check-up examinees to demonstrate the performance. Among the subjects, the genotype frequency of CYP1A1 Ile462Val was 56.8% for Ile/Ile, 38.1% for Ile/Val and 5.1% for Val/Val. The null type frequencies of GSTM1 and GSTT1 were 52.8% and 49.9%, respectively. And the genotype frequency of NQO1 C609T was 41.9% for C/C, 41.3% for C/T and 16.8% for T/T. Their distributions were similar to those reported for Japanese by other studies. To the best of our awareness, this is the first paper that reports the success in quadruplex PCR-CTPP. The applied polymorphisms are useful ones, which would be adopted not only for research purposes, but also for risk assessment of individuals exposed to carcinogenic substances. This convenient genotyping would be applied for cancer prevention especially in Asian Pacific regions, where expensive genotyping methods are hardly available.

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.