Background: Esophageal squamous cell carcinoma (ESCC) is one of the most lethal malignancies with poor prognosis. Recently, the discovery of the immunogenic proteins, cancer-testis antigens, have been vigorously pursued as targets for therapeutic cancer vaccines. Methods: A systematic screening strategy was adopted to screen cancer-testis genes (CTGs) in ESCC by integrating multiple public databases and RNA expression microarray data from 119 ESCC subjects. For our identified novel CTG, independent cohort with 118 ESCC patients were recruited to validate the protein level by immunohistochemistry. Furthermore, functional assays were used to determine the underlying mechanisms in vitro and in vivo. Findings: 21 genes were recognized as CTGs, in particular, CDCA5 was aberrantly upregulated in 99.16% (118/119) of ESCC specimens and higher CDCA5 mRNA expression showed significant association with poor ESCC prognosis (HR = 1.85, 95%CI: 1.14-3.01, P = 0.013). Subsequently, immunohistochemical staining further confirmed that positive CDCA5 protein expression was associated with advanced TNM stage and shorter overall survival rate (45.59% vs 28.00% for CDCA5-/+ subjects, P = 1.86×10-3). Mechanistic exploration revealed that the activation of CDCA5 is associated with gain of H3K27ac. Silencing of CDCA5 significantly suppressed proliferation, invasion, migration and apoptosis resistance in ESCC cells. What's more, mouse xenograft assay showed that repressed CDCA5 inhibited tumor formation in vivo (P
