Frequent gene amplification and overexpression of decoy receptor 3 in glioblastoma

The decoy receptor 3 (DcR3) gene is amplified at high frequency in human lung, colon, and liver cancers. DcR3 has been demonstrated to produce a secreted member of the tumor necrosis factor receptor superfamily that negatively regulates Fas-mediated apoptosis. In this study we examined DcR3 gene amplification, DcR3 mRNA expression, and DcR3 protein expression in 46 human astrocytic brain tumors by quantitative genomic PCR, quantitative reverse transcription-PCR, and immunohistochemistry, respectively. The DcR3 gene amplification was detected in none of 6 (0%) low-grade astrocytomas, 1 of 16 (6%) anaplastic astrocytomas, and 6 of 24 (25%) glioblastomas. Six of 7 (86%) cases with gene amplification exhibited both mRNA overexpression and/or protein overexpression, suggesting that DcR3 mRNA and protein were expressed more abundantly in the cases with gene amplification. We thus concluded that high DcR3 mRNA expression and protein expression may be positively related to the gene amplification in astrocytic brain tumors, especially glioblastomas. Further, we speculated that the DcR3 gene amplification with overexpression may be responsible for malignant features in glioblastomas.