Characterization of methylation status of the nuclear hormone receptor DAX-1 in human cancer
The orphan receptor DAX-1 plays an essential role in human development, steroid hormone synthesis and the maintenance of embryonic stem cell pluripotency. Recent studies have demonstrated DAX-1 is involved in cancer development, and, depending on the specific cancer type, has a negative or positive effect on cancer growth. In order to better understand the mechanism of DAX-1 gene regulation in various cancer cell lines, the epigenetic regulation of DAX-1 was investigated. Following confirming levels of DAX-1 expression at both the mRNA and protein levels, the overall methylation status of the DAX-1 gene was probed using methylation-sensitive restriction enzyme analysis. To determine the molecular mechanism of DNA methylation of the DAX-1 gene, chromatin immunoprecipitation assays identified key methylating proteins that localize to specific CpG islands in the DAX-1 promoter. In conclusion, this study demonstrates that methylation of key cytosine residues in CpG islands within the DAX-1 promoter play a central role in regulating DAX-1 expression and varying degrees of methylation result in differences in DAX-1 expression in human cancer cell lines.