Selective Requirement of MYB for Oncogenic Hyperactivation of a Translocated Enhancer in Leukemia.

In acute myeloid leukemia (AML) with inv(3)(q21;q26) or t(3;3)(q21;q26), a translocated GATA2 enhancer drives oncogenic expression of EVI1. We generated an EVI1-GFP AML model and applied an unbiased CRISPR/Cas9 enhancer scan to uncover sequence motifs essential for EVI1 transcription. Using this approach, we pinpointed a single regulatory element in the translocated GATA2 enhancer that is critically required for aberrant EVI1 expression. This element contained a DNA binding motif for the transcription factor MYB which specifically occupied this site at the translocated allele and was dispensable for GATA2 expression. MYB knockout as well as peptidomimetic blockade of CBP/p300-dependent MYB functions resulted in downregulation of EVI1 but not of GATA2. Targeting MYB or mutating its DNA-binding motif within the GATA2 enhancer resulted in myeloid differentiation and cell death, suggesting that interference with MYB-driven EVI1 transcription provides a potential entry point for therapy of inv(3)/t(3;3) AMLs.