Proteomics-based identification of autoantibody against heat shock protein 70 as a diagnostic marker in esophageal squamous cell carcinoma

Abstract Detection of novel tumor-related antigens and autoantibodies in cancer patients is expected to facilitate the diagnosis of early-stage malignant tumor and establish effective new immunotherapies. The purpose of this study was to identify novel tumor antigens in an esophageal squamous cell carcinoma (ESCC) cell line (TE-2) and related autoantibodies in sera from patients with ESCC using a proteomics-based approach. TE-2 proteins were separated by two-dimensional polyacrylamide gel electrophoresis, followed by Western blot analysis in which sera from patients with ESCC, healthy controls and patients with other cancers were tested for primary antibodies. Positive spots were excised from silver-stained gels and analyzed by matrix-assisted laser disorption/ionization time-of-flight mass spectrometry (MALDI-TOF/TOF-MS). Sera from patients with ESCC yielded multiple spots, one of which was identified as heat shock protein 70 (Hsp70) by MALDI-TOF/TOF-MS. Concentrations of serum Hsp70 autoantibody were significantly higher for patients with ESCC (mean, 0.412 ± 0.096 mg/ml) than for patients with gastric (0.236 ± 0.112 mg/ml, P P P