Proteomic-based identification of HSP70 as a tumor-associated antigen in ovarian cancer

Ovarian cancer commonly presents without prominent symptoms and is consequently diagnosed at advanced stages with unfavorable prognosis. Novel serological biomarkers for the early detection and clinical management of ovarian cancer are imminently needed. Proteomic-based methods for biomarker discovery are promising strategies implemented in cancer research. The aim of the present study was to identify new tumor antigens from the ovarian cancer cell line SKOV3 and their associated autoantibodies in sera of patients with ovarian cancer employing proteomic-based approaches. Proteins from the ovarian cancer cell line SKOV3 were extracted by two‑dimensional polyacrylamide gel electrophoresis (2-DE) followed by western blotting and antibody reaction with sera from patients with ovarian cancer and normal controls. Positive spots were excised from Coomassie blue‑stained gels and identified by liquid chromatography‑tandem mass spectrometry (LC-MS/MS). The 2-DE analysis results revealed a total of 14 protein spots on the gel, and 7 proteins were finally identified by LC-MS/MS. In the subsequent experiment, using immunoassay on ovarian cancer sera and tissue-array slides, the well-known protein HSP70 was selected in order to validate this proteomic-based approach. In conclusion, the proteomic method used in the present study is a powerful instrument for identifying novel serum markers that may exhibit clinical usefulness in cancer.