Localization of cytochrome P4502E1 enzyme in normal and cancerous gastric mucosa and association with its genetic polymorphism in unoperated and remnant stomach.

BACKGROUND: Exposure to nitroso compounds and the activity of cytochrome P450 2E1 (CYP2E1), an activation enzyme for these carcinogens, are important factors in gastric carcinogenesis. Here, we investigated the potential correlation between genetic variation in CYP2E1 and its enzyme expression as detected with immunohistochemical (IHC) staining and cancer susceptibility in unoperated and remnant stomach. METHODS: Expression of CYP2E1 in the stomach (n=117) was detected with IHC staining using a polyclonal anti-CYP2E1 antibody. Interindividual variation in CYP2E1 enzyme activity was then compared with genetic polymorphisms in the transcriptional flanking region of the CYP2E1 gene by restriction fragment length polymorphism (RFLP) detection using the Rsa I restriction enzyme. Genetic polymorphisms of Rsa I RFLP in CYP2E1 were investigated in 499 patients with gastric cancer (466 unoperated stomachs and 33 remnant stomachs) and 553 control patients with benign gastroduodenal diseases. RESULTS: Mucosal IHC staining for CYP2E1 was stronger in areas of intestinal metaplasia, particularly in endocrine cells, which stained consistently and strongly. Expression of CYP2E1 enzyme in areas of IHC staining were confirmed with Western blot analysis and showed a significant association between the degree of staining and the CYP2E1 genotype (p<0.01) in cancer tissues and in the foveolar epithelium of normal gastric mucosa. No association between specific CYP2E1 genotype and gastric cancer risk in the unoperated stomach was found in either the large study or the age- and gender-matched case-control study. However, the frequency of rare alleles (C1/C2 or C2/C2) was significantly higher in patients with cancer in the remnant stomach following gastrectomy than in controls subjects without cancer (odds ratio=2.8, 95% confidence interval=1.3-5.8) or those with primary gastric cancer (odds ratio=2.6, 95% confidence interval=1.3-5.5). CONCLUSIONS: CYP2E1 genetic polymorphisms might correlate with CYP2E1 enzyme expression levels in normal and cancerous gastric tissues. These polymorphisms do not influence the development of primary stomach cancer but may do so in specific conditions, such as the remnant stomach after gastrectomy.

Genetic variation in PSCA is associated with susceptibility to diffuse-type gastric cancer.

Gastric cancer is classified into intestinal and diffuse types, the latter including a highly malignant form, linitis plastica. A two-stage genome-wide association study (stage 1: 85,576 SNPs on 188 cases and 752 references; stage 2: 2,753 SNPs on 749 cases and 750 controls) in Japan identified a significant association between an intronic SNP (rs2976392) in PSCA (prostate stem cell antigen) and diffuse-type gastric cancer (allele-specific odds ratio (OR) = 1.62, 95% CI = 1.38-1.89, P = 1.11 x 10(-9)). The association was far less significant in intestinal-type gastric cancer. We found that PSCA is expressed in differentiating gastric epithelial cells, has a cell-proliferation inhibition activity in vitro and is frequently silenced in gastric cancer. Substitution of the C allele with the risk allele T at a SNP in the first exon (rs2294008, which has r(2) = 0.995, D' = 0.999 with rs2976392) reduces transcriptional activity of an upstream fragment of the gene. The same risk allele was also significantly associated with diffuse-type gastric cancer in 457 cases and 390 controls in Korea (allele-specific OR = 1.90, 95% CI = 1.56-2.33, P = 8.01 x 10(-11)). The polymorphism of the PSCA gene, which is possibly involved in regulating gastric epithelial-cell proliferation, influences susceptibility to diffuse-type gastric cancer.

Potential anthelmintics: polyphenols from the tea plant Camellia sinensis L. are lethally toxic to Caenorhabditis elegans.

A novel gallate of tannin, (-)-epigallocatechin-(2 beta-->O-->7',4 beta-->8')-epicatechin-3'-O-gallate (8), together with (-)-epicatechin-3-O-gallate (4), (-)-epigallocatechin (5), (-)-epigallocatechin-3-O-gallate (6), and (+)-gallocatechin-(4 alpha-->8')-epigallocatechin (7), were isolated from the tea plant Camellia sinensis (L.) O. Kuntze var. sinensis (cv., Yabukita). The structure of 8, including stereochemistry, was elucidated by spectroscopic methods and hydrolysis. The compounds, along with commercially available pyrogallol (1), (+)-catechin (2), and (-)-epicatechin (3), were examined for toxicity towards egg-bearing adults of Caenorhabditis elegans. The anthelmintic mebendazole (9) was used as a positive control. Neither 2 nor 3 were toxic but the other compounds were toxic in the descending order 8, 7 approximately 6, 9, 4, 5, 1. The LC(50) (96 h) values of 8 and 9 were evaluated as 49 and 334 micromol L(-1), respectively. These data show that many green tea polyphenols may be potential anthelmintics.

Normalization of pH level and gastric mucosa after eradication of H. pylori in the remnant stomach.

BACKGROUND: The Updated Sydney System (USS) is used to evaluate chronic gastritis and chronic atrophic gastritis (CAG) due to H. pylori infection. Here, we investigated USS scores and gastric juice pH levels in H. pylori infection-positive or -eradicated patients with remnant stomach after surgery. METHODS: Gastric juice pH levels were measured using pH test-tape in 197 patients (112 H. pylori-positive and 85 H. pylori-negative after eradication) who had undergone distal gastrectomy and conventional H. pylori eradication therapy. RESULTS: In H. pylori infection-positive remnant stomach cases, gastric juice pH showed a reverse correlation with pepsinogen I/II ratio, and H. pylori infection-negative patients following eradication showed associations with the degree of atrophy and intestinal metaplasia at both the anastomosis and in the corpus. Further, pH levels in these patients were normalized time depending after the eradication in the remnant stomach. CONCLUSIONS: Eradication therapy for the remnant stomach contributes to the possible improvement of stomach conditions by controlling the pH level of gastric juice. This effect will be protective against the risk of secondary stomach carcinogenesis in the remnant stomach.

Helicobacter pylori infection-negative gastric cancer in Japanese hospital patients: incidence and pathological characteristics.

We used Helicobacter pylori sero-positivity and mucosal atrophy as detected by the serum pepsinogen method to identify H. pylori infection-negative gastric cancer patients with or without atrophy. One hundred and six of 748 (14.2%) primary gastric cancer patients were infection-negative by a serum antibody detection system. Further, 121 (16.2%) of the 748 were negative for gastric mucosal atrophy by the pepsinogen method, of whom 15/748 (2.0%) were H. pylori-negative by pepsinogen I level (>70 ng/mL) and pepsinogen I/II ratio (>3.0). Twenty-seven of 782 (3.6%) gastric cancer patients were H. pylori-negative by antibodies and severe atrophy as determined by pepsinogen I level (<30 ng/mL) and pepsinogen I/II ratio (<2.0). H. pylori-negative gastric cancer patients with severe atrophy likely had a previous infection. These results indicate that the actual number of H. pylori-negative patients is 2.0% at minimum and 10.6% (14.2% minus 3.6%) at maximum in the general Japanese population. Five of 15 (33%) cases displaying neither anti-H. pylori antibodies nor atrophy were intestinal-type and 10 (67%) were diffuse-type adenocarcinomas. Thirteen surgical patients with primary gastric cancer displaying neither antibodies nor mucosal atrophy were further analyzed for pathological and phenotypic characteristics. The mucin phenotype was divided into four gastric, five gastric and intestinal, two intestinal and two null types, independent of histological classification. Intestinal phenotype elements were detected by Cdx2 immunohistochemical methods in nine of 13 (70%) cases examined. We conclude that a small fraction of gastric cancer patients displayed multifactorial carcinogenesis without H. pylori infection, indicating that gastric cancer risk still exists in the absence of H. pylori infection, at an incidence of 2.0% at minimum and 10.6% at maximum in the general Japanese population.

Interleukin-8, cyclo-oxygenase-2, and trefoil factor family 1 gene expression and their association with Helicobacter pylori infection in the remnant stomach.

PURPOSE: The risk factors for secondary stomach carcinogenesis after distal gastrectomy have not been evaluated in detail. METHODS: Using gastrointestinal endoscopy, we examined 112 patients who had undergone gastrectomy. Biopsy specimens were taken from the stoma and the upper corpus mucosa in the remnant stomach to examine the associations among Helicobacter pylori (H.pylori) infection, bile reflux, and the expressions of interleukin-8 (IL-8), cyclo-oxygenase-2 (COX-2), and trefoil factor family 1 (TFF1) genes in the stomach mucosa. RESULTS: The IL-8 levels in the corpus mucosa were significantly higher in the H.pylori-positive patients than in the H.pylori-negative patients (P = 0.015). The IL-8 levels were significantly higher in the stomal mucosa than in the corpus mucosa in the H.pylori-positive patients (P = 0.047). The COX-2 levels in the corpus mucosa tended to be higher in the H.pylori-positive patients, but these levels were not significantly different in the stoma mucosa. The COX-2 levels in the corpus were significantly higher after Billroth II (BII) anastomosis than after Billroth I (BI) anastomosis (P = 0.041). TFF1 expression in the stoma was higher in the H.pylori-positive patients than in the H.pylori-negative patients, but the difference was not significant. CONCLUSIONS: Both H.pylori infection and bile reflux increased IL-8 levels after BI anastomosis. Furthermore, COX-2 levels were higher after BII than after BI anastomosis. These indicators will become useful not only as biomarkers to predict the degree of inflammation in the stomach mucosa, but also as surrogate biomarkers to predict the risk of secondary stomach carcinogenesis in the remnant stomach mucosa.

On the structures of hydroxylated metabolites of estradiol 17-sulfate by rat liver microsomes.

The metabolism of estradiol 17-sulfate (ES) by hepatic microsomes of female rats produced four new metabolites in addition to 2- and 4-hydroxyestradiol 17-sulfates (2- and 4-OH-ES), which were detected on an HPLC chromatogram. By comparison with synthetic specimens, three of these compounds were identified as 6alpha-, 6beta-, and 7beta-hydroxyestradiol 17-sulfates. To elucidate the structure of the remaining metabolite, a large-scale incubation of ES was carried out, followed by isolation using preparative HPLC to give the single material, which was assigned as 15beta-hydroxyestradiol 17-sulfate by instrumental analyses. On the other hand, when ES was incubated with the microsomes of male rats, 2-OH-ES was produced accompanied by two minor products: 4-OH-ES and a metabolite of unknown structure. The results show clearly that the metabolism of ES by rat hepatic microsomes is remarkably different between the sexes.