Improving application of human leukocyte antigen genotyping in precision medicine

© 2018 Dr Michael ErlichsterVariation in the human leukocyte antigen (HLA) genes has been extensively associated with predisposition to autoimmune disease and adverse drug reaction. Translation of these associations to clinical practice has proven to be difficult due to the high cost and time burden of genetic testing. Additionally, understanding the value of prospective HLA associations in a research context is challenging due to the unparalleled polymorphisms of the HLA genes, as well as interactions between HLA variants. In this thesis, tools and methods are described which assist in the interpretation of prospective HLA associations and definition of the clinical role of HLA genotyping. Importantly, techniques that improve the efficiency of genetic testing of HLA variants are also reported

The Transcription Factor PU.1 Controls a Reversible Differentiation Program in Acute Myeloid Leukemia

Abstract Background: Acute myeloid leukemia (AML) is an aggressive malignancy characterized by clonal expansion of transformed myeloid precursors that fail to differentiate into mature cells. Since myeloid lineage maturation curbs self-renewal and is considered irreversible, engaging this process in AML is an attractive therapeutic strategy. Results: Normal myeloid differentiation requires the transcription factor PU.1 (SPI1), which is functionally compromised in several AML subtypes and is directly inhibited by the recurrent fusion oncoproteins AML1-ETO and PML-RARA. To examine the importance of PU.1 suppression in AML maintenance in vivo, we have combined RNAi-mediated PU.1 inhibition with p53 deficiency to drive highly aggressive AML in mice. Using these models we find that restoring endogenous PU.1 activity in established AML in vivo is sufficient to trigger robust transcriptional, immunophenotypic, and morphological differentiation of leukemic blasts, yielding polymorphonuclear, neutrophil-like cells. Maturation of AML is associated with significant loss of cell viability and yields sustained disease clearance in vivo. Although PU.1 restoration is potently anti-leukemic, remarkably we find that subsequent suppression of PU.1 in mature neutrophil-like cells reverts them to a transformed state within several days. While mature AML-derived cells are slower to form blast colonies in methylcellulose cultures, their clonogenic frequency is only reduced four-fold relative to AML blasts suggesting highly efficient de-differentiation. Conclusions: These results demonstrate that triggering myeloid differentiation can effectively resolve a p53-deficient model of treatment resistant AML, but also identify a previously unrecognised ability of AML cells to bidirectionally transition between transformed and differentiated states based on the activity of a single transcription factor. Our findings challenge the concept of 'terminal differentiation' in AML and highlight the importance of therapeutically eradicating leukemia cells at all stages of myeloid lineage maturation. Disclosures No relevant conflicts of interest to declare

Interconversion between Tumorigenic and Differentiated States in Acute Myeloid Leukemia

ISSN:1934-5909ISSN:1875-977