Abstract 798: Measuring TK1 autoantibodies in the serum of cancer and non-cancer patients

Abstract

Abstract One of the foremost problems in cancer is lack of a convenient, early detection method. Often malignancies are discovered too late, at stages that are so evolved that treatment becomes painful, expensive, or ineffective. Thymidine Kinase 1 (TK1) is an important nucleotide salvage pathway enzyme involved in DNA synthesis and repair. It has been shown that TK1 levels increase under normal cellular conditions typically during cell proliferation. However under malignant conditions, TK1 is over-expressed both in the cytosol of cancer cells and the serum of cancer patients. Consequently, serum TK1 levels (sTK1) are often used in cancer diagnosis and prognosis. We hypothesized that there may be autoantibodies against sTK1 in cancer patients because TK1 is generally intercellular and usually sequestered from the immune system. In order to investigate this hypothesis, we developed an ELISA in a 96 well plate format specifically to detect and measure the presence of autoantibodies against sTK1. Using purified TK1 as a capture antigen, we added serum from both pre-treatment cancer patients and age matched normal patients to detect any autoantibodies that interact with sTK1. Using two different types of primary, HRP conjugated antibodies, (Goat Anti-Human-HL & Goat Anti-Human-Fc) we were able to determine that there are antibodies to TK1 in the serum of both cancer and non-cancer patients. We eliminated the possibility that we were only detecting fragments of autoantibodies that were not true autoantibodies since our GAH-Fc antibody is specific to only intact antibodies. Furthermore, when we added TCEP (A common reducing agent which we used to remove the antibodies from the serum) to the serum, we saw a measurable signal reduction. Preliminary data suggest there are autoantibodies to TK1 in both cancer serum and normal serum. Further research is underway to elucidate the mechanisms responsible. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 798. doi:10.1158/1538-7445.AM2011-798