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 < 0.001) but not in patients with benign prostatic hyperplasia (BPH). LEDGF/p75 expression was detected in 93% of prostate tumors but not in normal prostate. Strong expression of the protein was observed in 61% of prostate tumors. Moderate to high expression was also detected in BPH tissue. Cleavage of LEDGF/p75 was detected in apoptotic prostate cells.
Conclusions: The high expression of LEDGF/p75 in prostate tumors and BPH could be induced by inflammation and oxidative stress. LEDGF/p75 cleavage fragments generated during prostate tumor cell death might trigger autoantibodies under inflammatory conditions in certain patients.
Copyright 2004 Wiley-Liss, Inc.