The Retinal Determination Gene Network can confer chemoresistant properties to AML

Acute Myeloid Leukaemia (AML) is a highly heterogeneous disease characterised by an abnormal transcriptional landscape that results in a block in normal blood cell differentiation and aberrant self-renewal. Dysregulation of Homeobox A9 (HOXA9) expression is a hallmark of multiple AML subsets. Although HOXA9 is critical for maintaining leukaemic transformation, it has proven to be a challenging druggable target, and the underpinning molecular mechanisms through which it promotes leukaemogenesis remain elusive. Here, we report the existence of a dichotomous expression profile between sine oculis homeobox 1 SIX1 and the well known HOXA9 interactors MEIS1 in monocytic zinc finger (MOZ) and mixed-lineage leukaemia (MLL) rearranged AMLs. We employed ChIP-seq, together with RNA-seq, to identify regions bound and transcriptionally upregulated in a MOZ-TIF2 driven model of AML. Using RNA-seq, we demonstrated that SIX1 and EYA1 (the well known SIX1 partner) potentiates the transforming capacity of HOXA9 to confer a greater level of differentiation block via suppression of myelo-monocytic programmes. We next sought to define the impact of pharmacologically destabilising the EYA1/SIX1 complex using Benzarone. Through a single cell RNA-Seq timecourse following treatment of MOZ-TIF2 cells with Benzarone, we provide evidence that disruption of EYA1 and its interactions results in differentiation of these cells. To prove the specificity of Benzarone towards EYA1, we also conducted RNA-Seq on cells expressing EYA1 and HOXA9 or HOXA9 alone.