Final Examination for the Degree of PhD Food Science - MATTHEW TCHENG

Examining Committee
Dr. Loong-Tak Lim, Chair
Dr. Paul Spagnuolo, Advisor
Dr. David Ma, Advisory Committee Member
Dr. Yoshi Mine, Department Member
Dr. Roy Golsteyn, External Examiner

TITLE: VERY LONG CHAIN FATTY ACID METABOLISM IS REQUIRED IN ACUTE MYELOID  LEUKEMIA

ABSTRACT: Acute myeloid leukemia (AML) is a devastating blood cancer characterized by the uncontrolled proliferation of abnormal myeloid blasts that fail to differentiate into functional blood cells. AML therapy has  remained virtually unchanged for the past four decades and triggers significant co-morbidities, preventing dose escalation in mature AML patients. Compared to normal hematopoietic cells, the AML population exhibited an abnormal mitochondrial phenotype sustained by an increased reliance on fatty acid oxidation (FAO) coupled to oxidative phosphorylation (OXPHOS), conferring a pro-survival advantage against  induction chemotherapeutics. Anti-AML FAO inhibitors have not been approved for clinical use or induced unacceptable liver toxicities. The lack of potential compounds for further clinical development
underscore the need to identify novel compounds that inhibit FAO in AML and are well-tolerated by the normal hematopoietic population. In chapters 4, 5, and 6, this thesis elucidated the mechanism of action of avocadyne (AYNE), a novel FAO inhibitor that selectively eliminates AML while sparing normal blood cells. In chapter 4, AYNE was identified as the active component of avocatin-B (avo-B), a 1:1 mixture of fatty alcohols AYNE and avocadene (AENE). In chapter 5, the very long chain acyl-CoA dehydrogenase (VLCAD), an intramitochondrial FAO enzyme that is overexpressed and previously unexplored in AML, was identified as the target of AYNE. Genetic ablation and pharmacological blockade of VLCAD suppressed FAO metabolism in the AML cell lines TEX and OCI-AML2 (AML2). Metabolic assessment of primary patient-derived and normal donorderived mononuclear cells (MNCs) using stable isotope tracers revealed two divergent metabolic fates, resulting in selective AML death and MNC survival. Genetic knockdown or pharmacological inhibition of VLCAD suppressed the engraftment capacity of AML, but not the normal hematopoietic populations, further highlighting the pre-clinical anti-AML efficacy of FAO inhibition at VLCAD. Chapter 6 demonstrated that the odd number of carbon atoms in the aliphatic linear chain, the terminal triple bond, and the (2R,4R)-stereochemistry of the hydroxyl groups were critical to AYNE’s ability to bind to VLCAD, inhibit FAO, and eliminate AML cells. In summary, this thesis identified VLCAD as a novel anti-AML target and highlighted the pre-clinical efficacy of targeting AML mitochondrial metabolism with AYNE, a selective FAO inhibitor.