High expression levels of MAGE-A9 are correlated with unfavorable survival in lung adenocarcinoma

// Xiaolu Zhai 1 , Liqin Xu 2 , Siya Zhang 1 , Huijun Zhu 3 , Guoxin Mao 1 , Jianfei Huang 3 1 Department of Chemotherapy, Nantong University Affiliated Hospital, Nantong 226001, Jiangsu, China 2 Department of Respiratory, Nantong University Affiliated Hospital, Nantong 226001, Jiangsu, China 3 Department of Pathology, Nantong University Affiliated Hospital, Nantong 226001, Jiangsu, China Correspondence to: Guoxin Mao, e-mail: maogx3333@163.com Jianfei Huang, e-mail: ntyydoctor@126.com Keywords: MAGE-A9, lung adenocarcinoma, immunohistochemistry, prognosis, apoptosis Received: August 25, 2015 Accepted: November 25, 2015 Published: December 23, 2015 ABSTRACT A variety of melanoma-associated antigen-A (MAGE-A) protein are commonly detected in lung cancers. Their biological function is not well characterized but may involve cell cycle progression and the regulation of apoptosis. We hypothesized that MAGE-A9 is involved in the regulation of apoptosis. To test this hypothesis, we evaluated MAGE-A9 protein expression by immunohistochemical staining and we assessed the relationship between the expression of MAGE-A9 and clinical pathological parameters. In addition, we investigated the effect of MAGE-A9 down-regulation in lung adenocarcinoma. The results showed that a high expression level of MAGE-A9 protein in lung adenocarcinoma tumor cells was related to larger tumor diameter ( P = 0.013) and poor differentiation ( P = 0.029). Cox regression analysis revealed that the expression of MAGE-A9 in lung adenocarcinoma tumor cells ( P < 0.001) is an independent prognostic factor in five-year survival rates. NSCLC cells with silenced MAGE-A9 had decreased cell proliferation, migration and invasion in cell culture compared to corresponding control cells. The NSCLC cells showing down-regulated MAGE-A9 induced the expression of apoptosis-associated proteins. In addition, MAGE-A9 was associated with resistance to conventional chemotherapeutic agents. Our findings provide evidence that MAGE-A9 could be a potential therapeutic target in NSCLC.