Potential application of alternatively glycosylated serum MUC1 and MUC5AC in gastric cancer diagnosis.

Post-transcription modification of proteins can be altered during carcinogenesis. In this study, quantitative sandwich enzyme immunoassays were utilized to explore the clinical diagnostic value of the alternatively glycosylated MUC1 and MUC5AC. Four pairs of antibodies were selected to construct quantitative sandwich enzyme immunoassay. Serum mucin levels of 104 primary gastric cancer patients and 120 healthy individuals were measured using the four antibody pairs. The detection sensitivities of each antibody pair against gastric cancers were 42.31%, 25.00%, 38.46% and 30.77% respectively, with a specificity of 90.00%, significantly higher than widely used tumor markers CEA (21.15%) and CA19-9 (18.27%). When monitoring in parallel with all of the four antibody pairs, the detection sensitivity increased to 75.00%, with the same 90.00% specificity. Immunoblotting of the serum samples using the anti-mucin antibodies revealed highly variable glycosylation patterns among gastric cancer patients. In addition, real-time PCR indicated the elevated mRNA levels of MUC1 and/or MUC5AC in gastric cancers. The cancer-specific epitopes were also detected in other alimentary canal epithelium cancers such as colonic, nasopharyngeal and esophageal cancers, but with much lower sensitivities. Our results suggested that alternatively glycosylated MUC1 and MUC5AC could be of significant potential as effective tumor markers in gastric cancer diagnosis.