Tumor antigens eliciting autoantibody response in cancer of gingivo-buccal complex

Cancer of the gingivo-buccal complex (GBC) is a major cancer in Indian men. This study reports the identification of tumor antigens, which elicit an antibody response in cancer of GBC using immunoproteomics. Proteins from KB cells separated by 2-D PAGE, were immunoblotted with IgG from sera of 28 cancer patients, 12 patients with leukoplakia, and 28 healthy individuals. Antigens detected by the IgGs from the patient's sera were different among different individuals with presence of any single antigen ranging from 7 to 79%. Several of these antigens have been identified by MS and confirmed by immunostaining. They are three forms of α-enolase, peroxiredoxin-VI, annexin-II, HSP70, pyruvate kinase, α-tubulin, β-tubulin, ATP-synthase, phosphoglycerate mutase (PGM), aldose reductase, triosephosphate isomerase, and cyclophilin-A. Except, HSP70, these antigens are being reported in cancer of GBC for the first time. Pyruvate kinase and aldose reductase have not been reported to elicit autoantibody response in any other cancer earlier. Initial results show that autoantibody response against α-enolase, HSP70, annexin-II, peroxiredoxin-VI, and aldose reductase are also seen in patients with leukoplakia of GBC, which suggest early occurrence of these autoantibodies during the process of oral carcinogenesis. These antigens can be further validated for their use in cancer management by immune intervention.