Application of a novel method to collect large amount of fecal mucosa in screening colorectal cancer / 中华胃肠外科杂志

<p><b>OBJECTIVE</b>To explore the application of a novel device of collecting large amount of fecal mucosa for detecting the DNA methylation and screening colorectal cancer.</p><p><b>METHODS</b>Preoperative complete fecal sample and surgical specimen of 10 patients with colorectal cancer, and complete fecal sample and normal bowel mucosal samples confirmed by colonoscopy of 6 hospitalization cases at The Third Affiliated Hospital, Nanjing University of TCM from March to April 2014 were collected. A self-made bowel mucosa collector (consisting of upper, middle, lower three containers of 1 000 ml volume, with filter screen in each bottom whose pore diameter is 100, 200 and 300 mesh.) was used to collect mucosal exfoliation cells. Fecal DNA kit was applied to extract DNA of exfoliation cells and the concentration and purity of DNA were measured by UV spectrophotometer (A260/A280), meanwhile DNA methylation of fecal fluid and mucosal tissues was detected by bisulfite sequencing pCR(BSP).</p><p><b>RESULTS</b>DNA methylation sequencing showed that FBN1, SPG20, and SNCA genes presented methylation in CpG island in fecal fluid and cancer tissues from 10 colorectal cancer patients, but did not presented methylation in fecal fluid and mucosa from 6 control cases. When fecal amount was below 100 g, collection rate of fecal fluid was 60% to 80%; when fecal amount was over 100 g, collection rate of fecal fluid was unstable. When fecal amount was 50 to 100 g, DNA A260/A280 value was 1.6 to 1.8, and DNA concentration was 5.0 to 56.1 ng/L.</p><p><b>CONCLUSION</b>Collection rate of fecal fluid with this self-made fecal mucosa collector is quite stable when managing fecal amount of 50 to 100 g once, and can obtain higher purity and concentration of DNA, meeting the demand of methylation detection for screening colorectal cancer.</p>

Screening and diagnostic value of the molecular markers of DNA methylation in colorectal neoplasma / 中华胃肠外科杂志

<p><b>OBJECTIVE</b>To screen the molecular markers of DNA methylation with potential diagnostic value, and to explore their methylation features in Chinese colorectal neoplasma in order to find out ones with higher diagnostic value.</p><p><b>METHODS</b>Tissue samples of colorectal cancer and normal adjacent mucosa(>10 cm distance to tumors) from 10 colorectal cancer patients undergoing operation, and tissue samples of colorectal adenoma from 10 patients undergoing endoscopic resection in our center from June to August 2013 were collected respectively. Methylation status of 8 genes, such as SNCA, MAL, INA, SPG20, FBN1, CNRIP1, TFPI2, OSMR, was detected by BSP and qMSP to screen genes with potential diagnostic valua. ROC curve was drawn to analyze its diagnostic value.</p><p><b>RESULTS</b>BSP measurement showed that the rate of DNA methylation of SNCA, SPG20 and FBN1 was 100% in colorectal cancer and adenoma, while no methylation was found in normal adjacent mucosa. The other 5 genes expressed in different extent in cancer, adenoma and normal adjacent mucosa. Among 10 cancer tissues and normal adjacent mucosa detected by qMSP method, positive SNCA methylation was found in 5 cases and 1 case respectively; positive SPG20 in 8 cases and 1 case respectively; positive FBN1 in 7 cases and 0 cases respectively, whose differences were significant (P=0.070, P=0.003 and P=0.007). The area under curve(AUC) of SNCA, SPG20, and FBN1 methylation for diagnosing colorectal cancer was 0.890, 0.730 and 0.880 respectively.</p><p><b>CONCLUSION</b>SNCA, SPG20 and FBN1 are potential genes with screening value for colorectal neoplasma.</p>