Candidate Biomarker Discovery For Distinguishing Gastric Cancer From Ulcer Using Lectin Microarray

Gastric cancer is the most common epithelial cancer worldwide and the second leadingcause of cancer death, with an incidence of18.9/100,000/year. In china, these are400,000new cases of gastric cancer and300,000deaths annually, making gastric cancer China’s thirdmost common type of cancer. Surgery is the only known cure, so new prognostic indicators ortumor markers are necessary to increase patient survival, treatment outcome, and facilitateearly diagnosis.The relation between gastric ulcer and cancer has long been disput ed ever sinceCruveilhier in1839first distinguished clearly between chronic ulcer and cancer bothclinically and pathologically, but there is accumulating evidence that gastric ulcer disease ispositively associated with the risk of developing stomach cancer. Discovery of a tool fordistinguishing early gastric cancer from ulcer is necessary.Protein glycosylation, the attachment of a saccharide moiety to a protein, is amodification that occurs posttranslationally. The difference in tissue distribution and substratespecificity toward peptides are related to the diverse functions of these different subtypes ofGalNAc-Tases. GalNAc-Tase expression pattern have been reported in several types ofcancers, including gastric cancer, which suggested that GalNAc played a key role in gastriccancer genesis.Lectin microarray is a sensitive tool with the potential to allow high-throught analysis ofcancer-associated changes in glycosylation, and it has been used for biomarker discovery forcancer.Methods：Human gastric ulcer and gastric cancer tissueswere obtained from AffiliateHospital of Beihua University (Jilin, China) as frozen tissues, and they were proved bypathologists.A lectin microarray was produced by using37lectins with different binding preferences covering N-and O-linked glycans. Each sample was observed consistently by three repeatedslides and the normalized medians of each lectin from9repeated blocks were averaged and itsSD was counted.Data are presented as means±SD for the indicated number of independent experiments.Statistical differences between groups were calculated by using Student’s two-tailed t-test.Differences were considered statistically significant for values.Result：Lectin histochemistry indicated that more positive cells and intensive stainingcould be visible in gastric cancer when compared with gastic ulcer using the selected twolectins (MPL and VVA), which was consistent with the results of lectin microarray, suggestingthat lectins-MPL and VVA could be used for distinguishing gastric cancer from ulcer.1. The types of glycoprotein expression and the numbers of sugar chain branch in gastriccancer tissue were increased compared with in gastric ulcer tissue through the lectinmicroarray analysis.2. The GalNAc′s content of glycoprotein in gastric cancer tissue was increasedcompared with in gastric ulcer tissue through the lectin microarray analysis.3. The GalNAc′s content combined with MPL specific and GalNAcα-Ser/Thr (Tn)′scontent combined with VAA specific in gastric ulcer tissue were high expression byimmunohistochemical study.4. The glycoprotein contains GalNAc combined with MPL or VAA specific was mainlyexpressed in the cytoplasm, and most color was tan and brown of moderate or strong stainingin gastric cancer tissue.5. All types of gastric cancer group showed strong staining, were significantly differencecompared with gastric ulcer. The results of lectins immunohistochemical were consistent withthe results of lectin chip.6. In different types of gastric cancer tissues, MPL specific glycoprotein containingGalNAc expression quantity order from high to low was: intra-mucosal carcinoma, signet ringcell carcinoma, adenocarcinoma, lymphatic metastatic carcinoid, undifferentiated carcinoma,adenocarcinoma;7. In different types of gastric cancer tissues, VAA specific glycoprotein containing GalNAc and GalNAcα-Ser/Thr（Tn）expression quantity order from high to low was:intra-mucosal carcinoma, signet ring cell carcinoma, carcinoma and undifferentiatedcarcinoma, adenocarcinoma, lymphatic metastasis adenocarcinoma.8. Lectins chip detection glycoprotein technology could provide the basis for earlydiagnosis and treatment of gastric cancer.