Mechanistic insights into the effect of RUNX1/ETO knockdown in t(8;21) AML

The mutation of transcription factor genes is a main cause for acute myeloid leukaemia. RUNX1/ETO, the product of the t(8;21) chromosomal translocation, subverts normal blood cell development by impairing myeloid differentiation. RUNX1/ETO knockdown alleviates this block, with a global reprogramming of transcription factor binding and initiation of myeloid differentiation. Co-depletion of the myeloid transcription factor C/EBPα with RUNX1/ETO suppressed this differentiation response. Furthermore, C/EBPα overexpression largely phenocopied the effect of RUNX1/ETO knockdown. Our data show that low levels of C/EBPα are critical to the maintenance of t(8;21) AML and that C/EBPα drives the response to RUNX1/ETO depletion. To examine how changes in transcription factor binding impact on the activity of cisregulatory elements we mapped genome wide promoter-distal-element interactions in a t(8;21) AML cell line, via Capture HiC, and found that hundreds of interactions were altered by RUNX1/ETO knockdown. Differentially interacting elements exhibited changes in C/EBPα binding and were enriched for the CTCF motif. Our results demonstrate that the presence or absence of RUNX1/ETO has a profound impact on the intra-nuclear organisation of t(8;21) AML cells, and indicate which transcription factors are driving these changes. This work provides a novel mechanism for the RUNX1/ETO mediated differentiation block in t(8;21) AML

C/EBPα overrides epigenetic reprogramming by oncogenic transcription factors in acute myeloid leukemia

Key Points C/EBPα directly represses the leukemia maintenance program; however, the pattern of repressed genes is specific for each type of AML. Overexpression of C/EBPα does not globally displace these proteins from their binding sites, but overrides their repressive activity.</jats:p

The oncogenic transcription factor RUNX1/ETO corrupts cell cycle regulation to drive leukemic transformation

Oncogenic transcription factors such as the leukemic fusion protein RUNX1/ETO, which drives t(8;21) acute myeloid leukemia (AML), constitute cancer-specific but highly challenging therapeutic targets. We used epigenomic profiling data for an RNAi screen to interrogate the transcriptional network maintaining t(8;21) AML. This strategy identified Cyclin D2 (CCND2) as a crucial transmitter of RUNX1/ETO-driven leukemic propagation. RUNX1/ETO cooperates with AP-1 to drive CCND2 expression. Knockdown or pharmacological inhibition of CCND2 by an approved drug significantly impairs leukemic expansion of patient-derived AML cells and engraftment in immunodeficient murine hosts. Our data demonstrate that RUNX1/ETO maintains leukemia by promoting cell cycle progression and identifies G1 CCND-CDK complexes as promising therapeutic targets for treatment of RUNX1/ETO-driven AML

Congenitally Malformed Hearts: Aspects of Teaching and Research Involving Medical Students

To appreciate congenital heart disease fully, a detailed understanding of the anatomical presentation, as well as the physiology, is required. This is often introduced at an advanced stage of training. Professor Anderson has been influential in the Clinical Anatomy Intercalated BSc programme at the University of Birmingham, in particular in his teaching on Sequential Segmental Analysis. This article describes the experiences of the latest cohort of students on this programme, who undertook varying research projects using the Birmingham Cardiac Archive, with the guidance of Professor Anderson. The projects outlined include various aspects of isomerism, encompassing both the cardiac and abdominal manifestations, as well as details of congenitally corrected transposition of the great arteries and prenatally diagnosed right aortic arch and double arch. These studies all aimed to increase the knowledge base of their respective cardiac malformations and provide a basis for further research

RUNX1-ETO Depletion in t(8;21) AML Leads to C/EBPα- and AP-1-Mediated Alterations in Enhancer-Promoter Interaction

Acute myeloid leukemia (AML) is associated with mutations in transcriptional and epigenetic regulator genes impairing myeloid differentiation. The t(8;21) (q22;q22) translocation generates the RUNX1-ETO fusion protein, which interferes with the hematopoietic master regulator RUNX1. We previously showed that the maintenance of t(8;21) AML is dependent on RUNX1-ETO expression. Its depletion causes extensive changes in transcription factor binding, as well as gene expression, and initiates myeloid differentiation. However, how these processes are connected within a gene regulatory network is unclear. To address this question, we performed Promoter-Capture Hi-C assays, with or without RUNX1-ETO depletion and assigned interacting cis-regulatory elements to their respective genes. To construct a RUNX1- ETO-dependent gene regulatory network maintaining AML, we integrated cis-regulatory element interactions with gene expression and transcription factor binding data. This analysis shows that RUNX1-ETO participates in cis-regulatory element interactions. However, differential interactions following RUNX1- ETO depletion are driven by alterations in the binding of RUNX1-ETO-regulated transcription factors

Small Molecule Inhibitor of CBFβ-RUNX Binding for RUNX Transcription Factor Driven Cancers

Transcription factors have traditionally been viewed with skepticism as viable drug targets, but they offer the potential for completely novel mechanisms of action that could more effectively address the stem cell like properties, such as self-renewal and chemo-resistance, that lead to the failure of traditional chemotherapy approaches. Core binding factor is a heterodimeric transcription factor comprised of one of 3 RUNX proteins (RUNX1-3) and a CBFβ binding partner. CBFβ enhances DNA binding of RUNX subunits by relieving auto-inhibition. Both RUNX1 and CBFβ are frequently mutated in human leukemia. More recently, RUNX proteins have been shown to be key players in epithelial cancers, suggesting the targeting of this pathway could have broad utility. In order to test this, we developed small molecules which bind to CBFβ and inhibit its binding to RUNX. Treatment with these inhibitors reduces binding of RUNX1 to target genes, alters the expression of RUNX1 target genes, and impacts cell survival and differentiation. These inhibitors show efficacy against leukemia cells as well as basal-like (triple-negative) breast cancer cells. These inhibitors provide effective tools to probe the utility of targeting RUNX transcription factor function in other cancers

Small Molecule Inhibitor of CBFβ-RUNX Binding for RUNX Transcription Factor Driven Cancers

Transcription factors have traditionally been viewed with skepticism as viable drug targets, but they offer the potential for completely novel mechanisms of action that could more effectively address the stem cell like properties, such as self-renewal and chemo-resistance, that lead to the failure of traditional chemotherapy approaches. Core binding factor is a heterodimeric transcription factor comprised of one of 3 RUNX proteins (RUNX1-3) and a CBFβ binding partner. CBFβ enhances DNA binding of RUNX subunits by relieving auto-inhibition. Both RUNX1 and CBFβ are frequently mutated in human leukemia. More recently, RUNX proteins have been shown to be key players in epithelial cancers, suggesting the targeting of this pathway could have broad utility. In order to test this, we developed small molecules which bind to CBFβ and inhibit its binding to RUNX. Treatment with these inhibitors reduces binding of RUNX1 to target genes, alters the expression of RUNX1 target genes, and impacts cell survival and differentiation. These inhibitors show efficacy against leukemia cells as well as basal-like (triple-negative) breast cancer cells. These inhibitors provide effective tools to probe the utility of targeting RUNX transcription factor function in other cancers