EYA4 Acts as a New Tumor Suppressor Gene in Colorectal Cancer.

ABSTRACT

A previous genome-wide methylation array for colorectal cancer (CRC) identified aberrant promoter methylation of eyes absent 4 (EYA4). However, the correlations between EYA4 methylation and gene expression, the role played by EYA4 protein in colorectal carcinogenesis, and results of the gene-enrichment and functional annotation analysis have not yet been established. We analyzed the EYA4 methylation status and found EYA4 promoter methylation in CRC cell lines (100%), CRC tissues (93.5%) and advanced adenoma tissues (50.7%), compared with normal mucosa (32.6%). There was a significant inverse correlation between EYA4 methylation and expression. EYA4 transfection led to inhibition of cell proliferation in colony assays and xenograft studies. On performing the gene-enrichment and functional annotation analysis, we observed that the differentially expressed genes have been associated with the Wnt and MAPK signaling pathways. Our results demonstrate that EYA4 is under epigenetic regulation in CRC. It is a candidate tumor suppressor gene that acts by inducing up-regulation of DKK1 and inhibiting the Wnt signaling pathway. In addition, EYA4 methylation may be identified in stool samples and it serves as a potential stool biomarker for detection of advanced adenoma and CRC.