Differential epigenetic regulation of Aiolos expression in human tumoral cell lines and primary cells

In order to investigate the epigenetic component of Aiolos regulation, we analyzed the methylation status of its 5′ CpG island in relation to histone modifications. Inhibition of CpG methylation restores Aiolos expression, as well as euchromatin-associated markers, in U937 and 1106 mel cell lines. DNA methylation and low levels of euchromatin-associated signatures are observed in U937 and 1106 mel cell lines, while the opposite characterizes Daudi, Jurkat, T and B cells. CpG methylation is not necessary to repress transcription in monocytes and melanocytes where silencing mechanism involves heterochromatin-associated signature. We show that DNA methylation directs Aiolos silencing and chromatin status in tumor cell lines, while in primary cells is mainly regulated by histone modifications.