Proteomic identification of dihydrolipoamide dehydrogenase as a target of autoantibodies in patients with endometrial cancer

Accumulating evidence shows that various types of cancers induce a specific immune response, resulting in the production of antibodies against self-components (autoantibodies). The aim of the present study was to identify antigens for autoantibodies in sera from endometrial cancer patients as novel diagnostic markers for the disease. The reactivity of individual sera from patients was examined by 2-dimensional (2-D) immunoblotting using HeLa cell lysates as antigens to identify autoantigens. ELISA was established to quantitatively measure autoantibody titer of patients' sera. A mitochondrial protein, dihydrolipoamide dehydrogenase (DLD), was identified as an autoantigen specific to endometrial cancer patients. The levels of immunoglobulin (Ig)A but not IgG autoantibody to DLD were significantly increased in the sera of endometrial cancer patients. IgA autoantibody against DLD could be a novel diagnostic marker for endometrial cancer.