Antinuclear autoantibodies in prostate cancer: Immunity to LEDGF/p75, a survival protein highly expressed in prostate tumors and cleaved during apoptosis

BACKGROUND Cancer patients produce autoantibodies to self‐proteins called tumor‐associated antigens (TAA). These autoantibodies represent potentially valuable tools for identifying novel biomarkers and therapeutic targets. This study was designed to identify TAA in prostate cancer (PCa). METHODS Serum autoantibodies to the survival protein lens epithelium‐derived growth factor p75 (LEDGF/p75) were detected by immunofluorescence microscopy, ELISA, and immunoblotting. Expression of LEDGF/p75 in prostate cells and tumors was evaluated by immunoblotting or immunohistochemistry. Apoptotic cleavage of LEDGF/p75 was detected by immunoblotting. RESULTS Anti‐LEDGF/p75 autoantibodies were detected by ELISA in 18.4% of PCa patients and 5.5% of matched controls (P