Abstract 4021: Breaking the dogma: AWT1 hypermethylation in myeloid leukemia despite high expression

Abstract Hematological malignancies are the sixth leading cause of cancer related death worldwide. The Wilms tumor 1 (WT1) gene is over-expressed in numerous cancers with respect to normal cells, and has either a tumor suppressor or oncogenic role depending on cellular context. WT1 has been shown to be detectable at low levels only in CD34+/CD38- hematological stem cells but is undetectable after differentiation. WT1 is reported to be an excellent marker for diagnosis and minimal residual disease in acute myeloid leukemia, but the underlying epigenetic alterations are unknown. Using 23 hematological cancer cell lines we confirm the high expression of WT1 and the transcripts derived the from alternative promoter regions (AWT1) in myeloid associated cancer cell lines. To determine if this expression profile is associated with lineage specific DNA methylation changes we performed bisulphite analysis across the loci. Surprisingly we observe hypermethylation of the AWT1 promoter region in despitehigh levels of expression. This hypermethylation is associated with the expected canonical histone modification signature, with high levels of H3K9me3 and low H3K4me3 or H3K9ac. Subsequent bisulphite pyrosequencing of the WT1 and AWT1 promoters in a 356 cytogenetically characterized hematological malignancies revealed that AWT1 was hypermethylated in 63% and WT1 in 8% of primary myeloid cancers at diagnosis, whereas only 26% and 27% where hypermethylated in primary lymphoid cancers. A subset of these patients were treated with decitabine (5-aza-2′-deoxycytidine), a DNA demethylation agent commonly used to treat myeloid leukemia and myeloproliferative disease. The AWT1 methylation state did not change during treatment suggesting that AWT1 methylation state does not correlate with drug response. Our data suggests that combining (A)WT1 expression and AWT1 methylation analyses will be a useful tool for diagnose and confirmation of myeloid-lineage malignancies. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 4021. doi:1538-7445.AM2012-4021