Identification of SEC61β and its autoantibody as biomarkers for colorectal cancer.
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 SEC61β with expression changes 3.3-fold and a marginal statistical significance (p=0.052) previously.


METHODS
SEC61β expression in CRC tissues was further analyzed by western blotting and immunohistochemistry. We next assessed the putative diagnostic value of the SEC61β autoantibody as a serum marker.


RESULTS
Using western blotting analysis, SEC61β expression was increased 1.9-fold in tumor tissues. Immunohistochemical analysis of 64 CRC specimens showed that SEC61β 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 SEC61β autoantibody from patients with CRC were 79% and 75%, respectively. Importantly, the results of the SEC61β autoantibody for early detection of colorectal cancer revealed a higher sensitivity of 77% than the carcinoembryonic antigen (CEA) assay.


CONCLUSIONS
Measurement of SEC61β autoantibody levels may provide an alternative detection indicator for CRC, particularly among early-stage patients.
Department of Colorectal Surgery, Chang Gung Memorial Hospital, Keelung, Taiwan.
Chung-Wei
CW
Fan
Chung-Chuan
CC
Chan
Kuei-Tien
KT
Chen
Jen
J
Twu
Ya-Shu
YS
Huang
Chia-Li
CL
Han
Yu-Ju
YJ
Chen
Jau-Song
JS
Yu
Yu-Sun
YS
Chang
Yung-Bin
YB
Kuo
Err-Cheng
EC
Chan
D001323:Autoantibodies / Q000276:immunology* / Q000378:metabolism*; D014408:Biomarkers, Tumor / Q000276:immunology* / Q000378:metabolism*; D016022:Case-Control Studies; D045744:Cell Line, Tumor; D015179:Colorectal Neoplasms / Q000378:metabolism*; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D008565:Membrane Proteins / Q000276:immunology* / Q000378:metabolism*; D000069816:SEC Translocation Channels
D001323:Autoantibodies; D014408:Biomarkers, Tumor; D008565:Membrane Proteins; D000069816:SEC Translocation Channels; C499388:SEC61B protein, human