Identification of SEC61 beta and its autoantibody as biomarkers for colorectal cancer

Abstract

Background: To identify novel serological biomarkers for human colorectal cancer (CRC). we analyzed CRC tissues using gel-assisted digestion and isobaric tags with related and absolute quantitation (iTRAQ) labeling mass spectrometry (MS). By comparing pairs of tumor tissues and matched normal tissues. we discovered the SEC61 beta with expression changes 3.3-fold and a marginal statistical significance (p=0.052) previously. Methods: SEC61 beta expression in CRC tissues was further analyzed by western blotting and immunohistochemistry. We next assessed the putative diagnostic value of the SEC61 beta autoantibody as a serum marker. Results: Using western blotting analysis. SEC61 beta expression was increased 1.9-fold in tumor tissues. Immunohistochemical analysis of 64 CRC specimens showed that SEC61 beta was positively detected in 64% of the tumors, but weakly or not detected in > 80% of the adjacent nontumor epithelial cells. Western blot analysis with plasma samples showed that the sensitivity and specificity of the SEC61 beta autoantibody from patients with CRC were 79% and 75%. respectively. Importantly, the results of the SEC61 beta autoantibody for early detection of colorectal cancer revealed a higher sensitivity of 77% than the carcinoembryonic antigen (CEA) assay. Conclusions: Measurement of SEC61 beta autoantibody levels may provide an alternative detection indicator for CRC, particularly among early-stage patients. (C) 2011 Elsevier B.V. All rights reserved.