Kurzfassung

Acute myeloid leukemia (AML) is a heterogeneous disease of the hematopoietic progenitor cell and evolves as a consequence of the stepwise accumulation of genetic lesions. Next generation sequencing (NGS) studies have started to reveal the genetic complexity of AML and identified recurrent mutations in specific functional categories. Within these categories, up to 70% of alterations are found in genes involved in epigenetic gene regulation including DNMT3A, TET1/2, IDH1/2 and EZH2. These...Acute myeloid leukemia (AML) is a heterogeneous disease of the hematopoietic progenitor cell and evolves as a consequence of the stepwise accumulation of genetic lesions. Next generation sequencing (NGS) studies have started to reveal the genetic complexity of AML and identified recurrent mutations in specific functional categories. Within these categories, up to 70% of alterations are found in genes involved in epigenetic gene regulation including DNMT3A, TET1/2, IDH1/2 and EZH2. These findings have prompted clinicians and pharmaceutic companies to develop novel “epigenetic” drugs (e.g. the DNA methyltransferase inhibitor 5-azacytidine) and specific inhibitors, however, responses are minor, in general of short duration, and no predictive biomarkers have been identified to date. From a biological point of view, the cellular consequences that originate from the acquisition of these specific alterations are poorly understood. In transformed leukemic blast cells the situation is further complicated by the existence of concomitant mutations, which itself can induce epigenetic dysregulation. For example, mutations of the receptor tyrosine kinase (RTK) FLT3, one of the most common mutated genes in AML (~30%, often in association with mutant DNMT3A), activate the histone deacetylase SIRT1, and mutant Janus kinase 2 (JAK2) has been shown to phosphorylate the arginine methyltransferase PRMT5 causing impaired histone methylation. Of note, several RTK-inhibitors have been developed and are currently investigated in clinical trials, however, their effects on epigenetic regulators and chromatin modifications have not been explored until now. A comprehensive insight of epigenetic gene regulation in the context of aberrant signal transduction may therefore guide future therapeutic strategies.

PhD project proposal
In this project we aim to understand the specific role of mutant FLT3 (FLT3-ITD) on epigenetic gene regulation. We will make use of several well characterized human AML cell lines and generate syngeneic cells expressing either wild-type FLT3 or FLT3-ITD. The PhD student will perform global gene expression profiling by RNA-sequencing, histone modifications will be investigated by ChIP-Seq analyses. Further, FLT3-ITD expressing cells will be treated with specific FLT3-inhibitors and their effects on global chromatin modification will be analysed. FLT3-ITD-dependent histone modifications and involved epigenetic regulators will be further characterized by immunoblot analysis, ChIP and shRNA-mediated gene knockdown allowing us to identify FLT3-ITD-specific epigenetic targets. Finally, promising therapeutic strategies will be evaluated at the leukemic stem cell level using a well-established murine Flt3+/ITD:Dnmt3afl/fl:Mx1-Cre+ leukemia model.

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