Although minimal invasive treatment is widely accepted in the early stages of gastric cancer (GCa), we still do not have any appropriate risk markers to detect residual neoplasia and the potential for recurrence. We previously reported that aberrant DNA methylation is an early and frequent process in gastric carcinogenesis and could be useful for the detection of gastric neoplasia. Our goal is to find and identify some candidate genes, using genome-wide DNA methylation analysis, as a treatment marker for early gastric cancer (EGC). We performed methylated CpG island amplification microarray analysis using 12 gastric washes (six each of pre- and post-endoscopic treatment in each of the same patients). We finally focused on Sox17 gene. We examined the DNA methylation status of Sox17 in a validation set consisting of 128 wash samples (pre, 64; post, 64) at EGC. We next carried out functional studies to identify Sox17. Sox17 showed significant differential methylation between pre- and post-treatments in EGC patients (Sox17, p < 0.0001). Moreover, treating GCa cells that lacked Sox17 expression with a methyltransferase inhibitor, 5-aza-2'-deoxycytidine, restored the gene's expression. Additionally, the introduction of exogenous Sox17 into silenced cells suppressed colony formation. Gastric wash-based DNA methylation analysis could be useful for early detection of recurrence following endoscopic resection in EGC patients. Our data suggest that the silencing of Sox17 occurs frequently in EGC and may play a key role in the development and progression of the disease.

We suggest that this system could be a good diagnostic tool for SSA/Ps using magnifying colonoscopy.

Background: A number of noninvasive tests have been developed to establish the presence of Helicobacter pylori infection. However, thus far these tests have only been capable of detecting its presence. An increasing number of antibiotic-resistant H. pylori infections have been reported and they are known to be correlated with 23S rRNA single nucleotide polymorphisms (SNPs). We hypothesized that genomic analysis of H. pylori recovered from gastric washes could not only be less invasive, but also useful as a screening test and for assessing the outcome of eradication therapy. Methods: Biopsy specimens and gastric washes were collected from 100 patients during endoscopic examination. Then we analyzed 23S rRNA, ureA, and cagA genes using PCR and high-throughput pyrosequencing analysis. Results: Forty-five percent (44/97) of patients tested positive for ureA and 42.3% (41/97) tested positive by a rapid urease test. One hundred percent (35/35) of patients who tested positive by both methods were observed to have the cagA gene. Among these 35 patients, 23S rRNA SNPs were present in 34.3% (12/35). Conclusions: Gastric wash-based PCR and a pyrosequencing assay were used to rapidly detect and estimate the number of 23S rRNA SNPs in clinical isolates of H. pylori. Not only is this a less invasive technique, but it can also diagnose drug resistance.

No abstract

Although minimal invasive treatment is widely accepted for early stage of gastric cancer (GCa), we still do not have any appropriate risk markers to detect residual neoplasia and some potential of recurrence. We previously reported that aberrant DNA methylation is an early and frequent process in gastric carcinogenesis and could be useful for detection of gastric neoplasia. Our goal is to find and identify some candidate genes as a treatment marker using genome wide DNA methylation analysis for early stage of gastric cancer (EGC). We studied Methylated CpG Island Amplification Microarray (MCAM) analysis using 12 gastric washes (each 6 before (Pre) and after (Post) endoscopic treatment in same patients). One of them are Sox17. We examined the DNA methylation status of Sox17 in a validation set consisting of 128 washes samples (Pre, 64: Post, 64) at EGC. We next identified functional studies about Sox17 as a putative tumor suppressor gene. Sox17 showed significantly differential methylation between before and after treatment in EGC patient (Sox17, p&lt;0.0001). Moreover, treating GCa cells that lacked Sox17 expression with a methyltransferase inhibitor, 5-aza-2′-deoxycytidine, restored the gene's expression. Moreover, introduction of exogenous Sox17 into silenced cells suppressed colony formation. Gastric washes based DNA methylation analysis is easy and useful for early detection of recurrence after ER in EGC patients. Our data suggest that silencing of Sox17 occurs frequently in EGC and may play a key role in development and progression of the disease. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 4020. doi:1538-7445.AM2012-4020