High expression and frequently humoral immune response of melanoma-associated antigen D4 in glioma.

MAGE-D4 is a novel member of MAGE super-family. It has preliminarily been demonstrated that MAGE-D4 mRNA is not expressed in majority of normal tissues except for brain and ovary in which only trace amount of MAGE-D4 mRNA can be detected, but predominantly expressed in glioma. MAGE-D4 protein expression and its immunogenicity in glioma have not been elucidated well. This study was designed to analyze MAGE-D4 expression both at mRNA and protein level, characteristic of humoral immune response, and their relationships with glioma patients' clinicopathological parameters. Recombinant MAGE-D4 protein and antiserum were generated. Quantitative RT-PCR analysis revealed that MAGE-D4 mRNA expression was overall up-regulated in 41 glioma specimens compared with that in 14 normal brain tissues. Immunohistochemistry analysis showed that 78% (21/27) glioma tissues expressed MAGE-D4 protein, which was predominantly located in the cytoplasm of tumor cells, but absent in any neuroglia cell of normal brain tissues. ELISA analysis demonstrated that humoral response against MAGE-D4 was detected in 17% (7/41) of glioma patients' sera but not in 77 healthy donors. No apparent correlation was observed between the expression and immunogenicity of MAGE-D4 with clinicopathological parameters of glioma. In summary, these results indicate that MAGE-D4 is highly expressed in glioma and can develop specifically humoral response in glioma patients, which supports that it may be a promising biomarker for glioma diagnosis and immunotherapy.