Chemoresistance Mechanisms In Acute Myeloid Leukemia Stem Cells

Abstract

Acute myeloid leukemia (AML) is characterized by poor clinical outcome due to high rates of relapse driven by therapy-resistant leukemic stem cells (LSC). Despite major advances in our understanding of the mechanisms that drive AML pathogenesis, our comprehension of responses to therapy remains poor, and treatment strategies have not dramatically changed over the past thirty years. In this dissertation, we directly evaluated LSC responses to induction therapy by performing gene expression profiling of LSC and non-LSC blast populations from paired diagnostic:post-induction therapy patient samples. Our work identified 5-lipoxygenase (5-LO), amongst several other genes, as potential chemoresistance mediators in AML LSCs. Confirmation of the broad role of 5-LO in leukemia was observed through loss-of-function studies in 5- LO deficient models of myeloid leukemogenesis, which exhibit improved survival and responses to chemotherapy both in vitro and in vivo. In contrast, 5-LO deficient hematopoietic stem/progenitor cells exhibit enhanced recovery in response to myeloablative therapy. Genetic and pharmacologic perturbation of 5-LO activity confirms that the leukotriene-synthetic capacity of 5-LO is a requirement for its chemoprotective effects. Together, our data identify multiple novel regulators of LSC chemoresistance and highlight 5-LO as a target for therapies that seek to enhance the effect of induction therapy.