This K22 Transition Career Development Award is designed to provide support to help facilitate career and research development. My (Brian Barth, Ph.D.) training thus far in the fields of lipid biochemistry, normal and malignant cell biology, and nanomedicine, has prepared me for a career as an independent academic researcher. My career goals are to obtain additional training to prepare me for a career as an independent tenure-track scientist, and to establish a dynamic research program at an academic institution that focuses on leukemia biology and experimental therapeutics. My research goals are to identify sphingolipid- and redox- mediated mechanisms that can be exploited for the development of translational anti-leukemia therapeutic strategies. This K22 proposal will provide me the necessary resources to accomplish these goals, which will make me more competitive for future R01 funding. This proposal provides a career training plan that includes informal mentoring from an advisory committee, didactic training, teaching and mentoring of others, as well as defined milestones. My advisory committee is a strength of the application, consisting of noted experts that will ensure the fulfillment of my career development plan. Of particular note, this plan will include research laboratory training in each of their respective laboratories. This K22 proposal also includes a novel research project focused on evaluating a role for autophagy regulation of ceramide metabolism and activation of the NADPH oxidase in the pathobiology of acute myeloid leukemia (AML). The most common type of leukemia in adults is AML. An understanding of the underlying molecular mechanisms that mediate the underlying biology of AML is essential to the development of preventative and therapeutic strategies. Ceramide is a bioactive sphingolipid long implicated as a regulator of cellular stress and apoptosis. However, recent evidence has emerged challenging this dogma and suggesting that ceramide species are elevated in primary malignant specimens and as a function of disease stage/prognosis. NOX enzymes have gained notoriety as key players in normal cellular homeostasis as well as a variety of pathological processes. NOX enzymes play key roles in the regulation of cellular processes by modulation of redox-sensitive phosphatases and transcription factors, and have been shown to be stimulated by ceramide. NOX has also been shown to affect proliferation in AML, influence monocytic AML subtypes ability to interfere with normal immunity, and to affect oxidative signaling in AML. The generation of ceramide by complex sphingolipid turnover, or through exogenous supply, is mediated through lysosomal catabolic pathways yet the process of ceramide-regeneration is not understood. In this research study, autophagy will be investigated as a mechanism of ceramide-regeneration given preliminary data suggesting its elevation in AML as well as the elevation of ceramide in poor prognosis AML.
The specific aims of this research study are to: 1) evaluate a role for autophagy in the regulation of ceramide metabolism in AML, and 2) evaluate NADPH oxidase activation as a pro-leukemogenic pathway mediated by ceramide in AML. It is hypothesized that autophagy will regulate the generation and accumulation of endogenous ceramides in poor prognosis AML, and that this elevation in ceramides will trigger NOX activity that will augment pro-growth and pro-survival signaling pathways otherwise upregulated by leukemogenic transformations. To test this hypothesis, ceramide accumulation and therapeutic sensitivity will be evaluated following pharmacological or molecular inhibition of autophagy as well as NOX. Additionally, murine models engrafted with human patient AML will be treated with autophagy and NOX inhibitors in combination with ceramide-based therapeutics. Overall this K22 proposal will provide for: 1) career development plan that with allow me to establish myself as an independent translational leukemia researcher, and 2) research support that will demonstrate a role for autophagy in the regulation of ceramide metabolism in AML, as well as a role for ceramide-activated NOX in the pathobiology of AML. Finally, this proposal will lead to the development of autophagy and NOX inhibitors as agents to combine with ceramide-based anti-AML therapeutics.
Acute myeloid leukemia (AML) is a hematological disorder with profoundly poor clinical outlook. This study will evaluate autophagy regulation of ceramide metabolism and activation of the NADPH oxidase in the pathobiology of AML.