BMI-1 autoantibody in serum as a new potential biomarker of nasopharyngeal carcinoma.

BMI-1 is overexpressed in a variety of cancers, which can activate the immune system to produce antibodies in tumor tissues. In this study, we isolated phage expressing BMI-1 protein by screening of a mixture of nasopharyngeal carcinoma (NPC) cDNA T7 phage library and found that the antibody against BMI-1 was elevated in the sera from NPC patients. BMI-1 mRNA was overexpressed at different levels in seven NPC cell lines compared with normal nasopharyngeal epithelial cell line NP69. Histochemistry showed that patient sera were more reactive with BMI-1 than normal sera. Antibody affinity assay using sera from 40 NPC patients and 54 controls showed that BMI-1 antibody was significantly greater in patient sera than in normal controls (patient 0.791 +/- 0.025 and normal 0.488 +/- 0.042; P < 0.001) and the BMI-1 autoantibody be significantly related with the progress of NPC (Benign versus LNPC P=0.001; LNPC versus MNPC P=0.047). Analysis of the results with logistic regression and receiver operating characteristics (ROC) curves showed that BMI-1 antibody was a modest marker for NPC (sensitivity 0.74 and specificity 0.73; AUC = 0.8044). The showed that BMI-1 antibody as a potential marker of NPC may be rational, and could have diagnostic and prognostic value.