The EPH Receptor Bs (EPHBs) Promoters are Unmethylated in Colon and Ovarian Cancers

Abstract

Aberrant expression of EPH receptors and their ligands, ephrins, has been reported in a large variety of human cancers, including epithelial cancers from the colon and ovary. Due to the recently reported decrease or loss of EPHBs expression in colorectal carcinomas and the abundance of CpG sites in their promoters, we analyzed the promoter methylation status of three members of the EPHB family, EPHB2, EPHB3 and EPHB4, in a series of 22 colon cancer cell lines, as well as in four ovarian cancer cell lines and 56 ovarian tumor samples. The promoters of the three receptor genes were unmethylated in the vast majority of samples as assessed by methylation-specific polymerase chain reaction (MSP). These results were confirmed by direct bisulphite sequencing. Furthermore, from RT-PCR analyzes and Northern blotting, EPHB2 showed only small variation in RNA expression across ovarian cancer cell lines and clinical samples. We conclude that promoter hypermethylation of EPHB2, EPHB3 and EPHB4 is not a common event in colon and ovarian cancers, and therefore plays no major role in these tumors.