1002 - LOOPING AND LEUKAEMIA: ALTERATIONS IN DNA TOPOLOGY SHAPE MALIGNANT TRANSCRIPTIONAL PROGRAMMES

Abstract

Cancer is initiated and maintained by malignant transcriptional programmes, with acute myeloid leukaemia (AML) an exemplar of this process. AML is associated with mutations in multiple transcriptional and epigenetic regulators and aberrant expression patterns in AML can be used to classify and provide prognostic and predictive data to personalise therapy and improve patient outcomes. However, while transcriptional outputs resulting from these lesions have been described in both model systems and patient samples, the mechanistic detail of how chromatin accessibility, chromatin activity and three dimensional DNA topology change in a coordinated manner to generate the aberrant transcriptional programmes that drive the leukaemia phenotype and how this is altered in a longitudinal fashion, is lacking. I will discuss an unpublished project that uses integrative analyses to address this question and its role in AML evolution. This involves integrative genomic analysis of haematopoioetic stem and progenitor cells (HSPC) from an allelic series of mouse models, that are either normal (WT), contain a single mutation (Nucleophosmin – NPM or Fms like tyrosine kinase 3 – FLT3) that confers a subtle pre-malignant phenotype, or carry both mutations (double mutant- DM) and develop short latency aggressive AML. These alleles have been chosen due to their recurrent and common nature, the availability of representative mouse models and their lack of direct association with transcription, epigenetic regulation or enhancer function. Integrating RNA-Seq, ChIP-Seq, ATAC-Seq and promoter based capture Hi-C, I will describe how the patterns of chromatin accessibility and modification change from normal through the intermediate pre-malignant stages (single mutants) to the DM leukaemia stage and link these with dynamic promoter-enhancer interaction data and gene expression. These analyses identified putative network nodes and players critical for leukaemia maintenance and subsequent validation of these candidates will be demonstrated in functional and transcriptional assays