Introduction: Risk prediction of gastric cancers is important to implement appropriate screening procedures. Although aberrant DNA methylation is deeply involved in gastric carcinogenesis, its induction by Helicobacter pylori, a strong gastric carcinogen, is unclear. Here, we analyzed the effect of H. pylori infection on the quantity of methylated DNA molecules in noncancerous gastric mucosae and examined its association with gastric cancer risk. Experimental Design: Gastric mucosae were collected from 154 healthy volunteers (56 H. pylori negative and 98 H. pylori positive) and 72 cases with differentiated-type gastric cancers (29 H. pylori negative and 43 H. pylori positive) by endoscopy. The numbers of DNA molecules methylated and unmethylated for eight regions of seven CpG islands (CGI) were quantified by quantitative PCR after bisulfite modification, and fractions of methylated molecules (methylation levels) were calculated. Results: Among healthy volunteers, methylation levels of all the eight regions were 5.4-to 303-fold higher in H. pylori positives than in H. pylori negatives (P < 0.0001). Methylation levels of the LOX, HAND1, andTHBD promoter CGIs and p41ARC exonic CGI were as high as 7.4% or more in H. pylori^positive individuals. Among H. pylori^negative individuals, methylation levels of all the eight regions were 2.2-to 32-fold higher in gastric cancer cases than in age-matched healthy volunteers (P V 0.01). Among H. pylori^positive individuals, methylation levels were highly variable, and that of only HAND1 was significantly increased in gastric cancer cases (1.4-fold, P = 0.02). Conclusions: It was indicated that H. pylori infection potently induces methylation of CGIs to various degrees. Methylation levels of specific CGIs seemed to reflect gastric cancer risk in H. pylori^negative individuals.Gastric cancer is one of the most common malignancies worldwide and remains a leading cause of cancer death in Asia and some European countries (1). To reduce its mortality, early detection by endoscopy and curative resection are important (2). However, considering the potential risk and costs of early detection by endoscopic examination, implementation reflecting an individual's risk for developing a gastric cancer would be ideal. Also, endoscopic mucosal resection, which conserves the noncancerous gastric mucosae, is becoming popular, and the problem of metachronous gastric cancer recurrence is being recognized (3). Again, if the future risk of developing metachronous cancers in a specific case can be estimated, the information will be useful in the decision on either surgical resection or endoscopic mucosal resection for the case.The major etiologic risk factor for gastric cancers is Helicobacter pylori infection, which increases gastric cancer risk 2.2-to 21-fold (4 -6). In an animal model with Mongolian gerbil chronic infection with H. pylori rarely induces gastric cancers by itself, but markedly enhances their incidences after initiation with a mutagen, such as N-methyl-N-nitrosourea (7). Thi...

A signi®cant portion of gastric cancers exhibit defective DNA mismatch repair, manifested as microsatellite instability (MSI). High-frequency MSI (MSI-H) is associated with hypermethylation of the human mut-L homologue 1 (hMLH1) mismatch repair gene promoter and diminished hMLH1 expression in advanced gastric cancers. However, the relationship between MSI and hMLH1 hypermethylation has not been studied in early gastric neoplasms. We therefore investigated hMLH1 hypermethylation, hMLH1 expression and MSI in a group of early gastric cancers and gastric adenomas. Sixty-four early gastric neoplasms were evaluated, comprising 28 adenomas, 18 mucosal carcinomas, and 18 carcinomas with super®cial submucosal invasion but clear margins. MSI was evaluated using multiplex uorescent PCR to amplify loci D2S123, D5S346, D17S250, BAT 25 and BAT 26. Methylation-speci®c PCR was performed to determine the methylation status of hMLH1. In two hypermethylated MSI-H cancers, hMLH1 protein expression was also evaluated by immunohistochemistry. Six of sixty-four early gastric lesions were MSI-H, comprising 1 adenoma, 4 mucosal carcinomas, and 1 carcinoma with super®cial submucosal invasion. Two lesions (one adenoma and one mucosal carcinoma) demonstrated low-frequency MSI (MSI-L). The remaining 56 neoplasms were MSI-stable (MSI-S). Six of six MSI-H, one of two MSI-L, and none of thirty MSI-S lesions showed hMLH1 hypermethylation (P50.001). Diminished hMLH1 protein expression was demonstrated by immunohistochemistry in two of two MSI-H hypermethylated lesions. hMLH1 promoter hypermethylation is signi®cantly associated with MSI and diminished hMLH1 expression in early gastric neoplasms. MSI and hypermethylation-associated inactivation of hMLH1 are more prevalent in early gastric cancers than in gastric adenomas. Thus, hypermethylation-associated inactivation of the hMLH1 gene can occur early in gastric carcinogenesis. Oncogene (2001) 20, 329 ± 335.

Reduced chemosensitivity to hypoxia and blunted perception of dyspnea may predispose patients to fatal asthma attacks.

The E-cadherin promoter frequently undergoes hypermethylation in human gastric cancers, particularly those of the undifferentiated-scattered histologic subtype. E-cadherin promoter hypermethylation is associated with decreased expression and may occur early in gastric carcinogenesis.

The increase in thickness of bronchial walls by such structural changes as subepithelial fibrosis contributes to the severity and chronicity of asthma by amplifying airway narrowing. However, the pathogenesis of this structural alteration is not known. Transforming growth factor beta 1 (TGF beta 1) is known to have biologic activities relevant to the cellular and molecular events in subepithelial fibrosis, such as the deposition of collagen I and III and the increase of myofibroblasts beneath the epithelial basement membrane. Therefore, we examined TGF beta 1 gene expression in bronchial biopsy tissues from five severe asthmatics, five mild asthmatics, and five normal subjects using in situ hybridization combined with histochemical staining. Cells expressing TGF beta 1 mRNA were detected in tissues from four normal subjects, one mild asthmatic, and five severe asthmatics. The density of positive cells in severe asthmatic tissues (52.1 +/- 22.7, mean +/- SD/mm2) was significantly greater than that in mild asthmatic tissues (1.0 +/- 1.9/mm2, P < 0.01) or normal tissues (10.5 +/- 10.6/mm2, P < 0.02). The density in mild asthmatic tissues was not significantly different from that in normal tissues. The vast majority of positive cells in severe (99.1 +/- 1.7%) and mild (100%) asthmatic tissues were identified as eosinophils. In contrast, eosinophils constituted a small portion of positive cells (20.8 +/- 21.6%) in normal tissues. These results indicated that TGF beta 1 mRNA was overexpressed in severe asthmatics and that the main source of the mRNA was eosinophils, suggesting that eosinophils play an important role in the pathogenesis not only of inflammation but also of structural changes, such as subepithelial fibrosis, in asthmatic airways.