Detection of autoantibodies to annexin A11 in different types of human cancer

Introduction: Annexin A11 was previously identified as an autoantigen in 4.1-10.1% of patients with various systemic autoimmune diseases. In this study, an enzyme-linked immunosorbent assay (ELISA) was developed to investigate the occurrence and features of anti-annexin A11 autoantibodies in sera from patients with different types of cancer. Methods: The recombinant protein of GST fused to the N-terminal domain (1-175 residues) of human annexin A11 was expressed and used as antigen in ELISA. A total of 246 serum specimens were analyzed, which includes sera from healthy women (77), patients with ovarian cancer (72), breast cancer (18), colon cancer (19), pancreatic cancer (20), prostate cancer (20), and diabetes (20). Results: The overall titer of anti-annexin A11 autoantibodies in ovarian cancer patients (or primary tumors only) was found much higher than that in healthy controls (P<0.05). At the cut-off value designating positive reaction, anti-annexin A11 autoantibodies were detected in 12.5% (5/40) of primary ovarian cancer patients with a significant difference from 2.6% (2/77) of the healthy controls (P<0.05), but only in 6.25% (2/32) of recurrent tumors. ROC curve demonstrated the potential diagnostic value of anti-annexin A11 autoantibodies in primary ovarian cancer patients with an AUC of 0.62 (0.52-0.73). Anti-annexin A11 autoantibodies were also detected in 5.26% (1/19) of colon cancer and 10% (2/20) of diabetes patients but without significant difference from the healthy controls. Conclusion: A convenient assay to detect anti-annexin A11 autoantibodies in patients was developed, and the experimental data are promising but need to be expanded to address their biological/clinical relevance.