Abstract 878: Identification and characterization of tumor-associated antigens as biomarkers in human prostate cancer

Abstract

Abstract Autoantibodies against intracellular antigens are commonly found in a number of systemic autoimmune diseases. Their utility in providing insights into molecular and cellular biology and in the differential diagnosis of autoimmune diseases is well documented. Autoimmune phenomena manifested as antibodies to cellular components have been described in many types of cancer. Prostate cancer (PCa) is the most frequently diagnosed cancer in men and the second leading cause of male cancer deaths in the United States. PCa also presents the greatest racial disparity in this country, with an incidence and mortality in African-American men that is 3 times higher than in White and Latino men. Reducing these disparities would require a multi-faceted approach that includes developing more effective screening method for the early detection of PCa. The objective of this study is to analyze the frequency and specificity of autoantibodies in PCa patients, and further to identify and characterize the targeted tumor-associated antigens. In this study, 34 sera from PCa patients, and 30 sera from normal human individuals were examined for autoantibodies using indirect immunofluorescence (IIF) assay and western blotting. Autoantibodies were detected in 18 of 34 (52.9%) PCa sera by IIF, which was significantly higher than that in normal human sera. Of the interest is that of 34 PCa sera, 9 (26.5%) sera were identified by western blotting analysis containing antibodies against an unknown 70kDa cellular protein and 23.5% PCa patients showed antibody to 45 kDa protein. No reactivity with 70KDa and 45kDa proteins was detected in 30 normal human sera. In the further study, these cellular proteins targeted by serum antibodies in PCa were identified by using two-dimensional gel electrophoresis (2DE) and liquid chromatography-tandem-mass spectrometry (LC-MS/MS). This preliminary data supports that autoimmune responses to certain cellular proteins maybe a by-product in the transformation to PCa, and further studies of novel targeted proteins in PCa may provide insights into how these proteins might be involved in malignancy. Citation Format: Jitian Li, Liping Dai, Carlos A. Casiano, Jianying Zhang. Identification and characterization of tumor-associated antigens as biomarkers in human prostate cancer. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 878. doi:10.1158/1538-7445.AM2014-878