Correlation between the high expression levels of cancer-germline genes with clinical characteristics in esophageal squamous cell carcinoma.

Antigens encoded by cancer-germline genes are attractive targets for cancer immunotherapy. In this study, we aimed to evaluate the mRNA expression of cancer-germline genes, expression of the encoded proteins in patients with esophageal squamous cell carcinoma (ESCC) and their correlations with clinical characteristics. In addition, the effects of downregulation cancer-germline genes on ESCC cells were assessed in vitro. Our results showed that cancer-germline genes were frequently expressed in ESCC samples. The positive rates of in ESCC samples were: 87% of MAGE-A3, 60% of MAGE-A4, 65% of MAGE-C2, and 20% of NY-ESO-1 at mRNA level. MAGE-A3 expression was associated with age, lymph node metastasis and tumor stage (all P<0.05), while MAGE-C2 expression was only associated with tumor stage (P<0.05). Furthermore, the MAGE-A3 expressing patients had a poorer overall survival (P<0.05). Multivariate analysis identified MAGE-A3 as an independent poor prognostic marker in ESCC. In vitro assay, ESCC cell lines treated with specific siRNAs to down-regulate MAGE-A3 and MAGE-C2 resulted in decreased colony-formation and migration ability (P<0.05). Epithelial marker E-cadherin was up-regulated in siRNA-MAGE-A3/C2 cells compared to controls, whereas mesenchymal markers Vimentin, N-cadherin and Slug were downregulated (all P<0.05), suggesting a role for MAGE-A3/C2 in ESCC metastasis through inducing epithelial-mesenchymal transition. The present study revealed that cancer-germline genes and their encoded proteins were frequently expressed in ESCC tumor samples and were related to poor prognosis. Thus, cancer-germline genes may serve as useful biomarkers and potential targets for ESCC patients.