Expression of MAGE-D4, a novel MAGE family antigen, is correlated with tumor-cell proliferation of non-small cell lung cancer.

MAGE-D4, originally termed MAGE-E1, is a novel MAGE family gene that is expressed at high levels in malignant tumors as compared to normal tissue. The present study was conducted to assess the clinical significance of MAGE-D4 expression in non-small cell lung cancer (NSCLC). Expression of MAGE-D4 protein was estimated by immunohistochemistry and MAGE-D4 mRNA expression was investigated using quantitative reverse transcription-PCR (RT-PCR). We assessed MAGE-D4 expression in NSCLC tissues and was found to be up-regulated in tumor tissues compared with normal lung tissues (mean MAGE-D4/GAPDH values, 0.035 for tumor tissues and 0.009 for normal lung tissues; p=0.002). However, there was no significant difference in MAGE-D4 expression among different pathological stages. The proliferative activity of tumor cells was significantly higher in high MAGE-D4 tumors (mean proliferative indices, 58.3 for high MAGE-D4 tumor levels and 34.0 for low MAGE-D4 tumor levels; p<0.001). In addition, a high MAGE-D4 expression was more frequently seen in squamous cell carcinoma than in adenocarcinoma (p=0.008), and less frequently in well-differentiated tumors than in moderately to poorly differentiated tumors (p=0.036). There was no difference in the postoperative survival between low and high MAGE-D4 patients (5-year survival rates, 65% and 69%, respectively; p=0.742). MAGE-D4 plays some roles in tumor cells proliferation in NSCLC, but MAGE-D4 expression status did not provided a prognostic significance.