XAGE-1 mRNA expression in prostate cancer and antibody response in patients

To evaluate the feasibility of cancer vaccine targeting XAGE-1, we investigated the expression of 4 XAGE-1 transcript variants and the humoral immune response to XAGE-1 in prostate cancer patients. XAGE-1a, b, c, d mRNA expression was analyzed in 54 prostate cancer specimens and 8 specimens of benign prostate hypertrophy (BPH) by reverse transcription-polymerase chain reaction (RT-PCR). The humoral response to XAGE-1 was investigated in sera obtained from 278 patients with prostate cancer and 40 healthy volunteers by enzyme-linked immunosorbent assay (ELISA) using recombinant protein. XAGE-1b mRNA expression was observed in 14 of 54 (26%) prostate cancer specimens, while XAGE-1a, c, and d mRNA expressions were observed in 1, 1, and 3, respectively. None of the 4 XAGE-1 transcript variants was observed in the 8 BPH specimens. Antibody against XAGE-1 was detected in sera from 2 of 129 stage D2 patients, whereas none of sera from 149 patients with localized prostate cancer or lymph node metastasis had detectable XAGE-1 antibody. No reactivity to XAGE-1 was found in sera from the 40 healthy individuals.