CXCR2-mediated modifications to bone marrow vasculature in chronic myeloid leukemia - PROJECT SUMMARY This F30 application describes a four-year plan for mentored research and career development for the PI, Alecia Alto. The scientific premise of this proposal is focused on the role of bone marrow endothelial cells (BMECs) and their contributions to pro-inflammatory signaling in chronic myeloid leukemia (CML). CML is responsible for 15% of adult leukemia cases and tyrosine kinase inhibitors (TKI) are the mainstay of treatment. However, TKI treatment does not eliminate quiescent leukemic stem cells (LSCs), and 80-85% of CML patients who respond to therapy are at risk of relapse upon TKI discontinuation. Studies linking prolonged inflammatory signaling and bone marrow remodeling in CML suggest that disrupting the interactions between stromal cells and LSCs may restore healthy hematopoietic function. mRNA sequencing of CML patient bone marrow from the lab of Dr. Ravi Bhatia, sponsor of the PI, has discovered elevated levels of CXCL8 and CXCL1, ligands for the chemokine receptor CXCR2, in patients with recurrence after TKI cessation. In CML mice, the lab has also shown that TNFα induces CXCL1, the murine homolog of CXCL8, to support CML LSCs. Although bone marrow vasculature is significantly altered in CML and BMECs both respond to and are a source of inflammatory chemokines, their role in maintaining CML LSCs has not been studied. Preliminary data from this proposal suggests that CML BMECs overexpress CXCR2 and gene signatures related to endothelial dysfunction, and continue to produce CXCL1 after TKI treatment. Therefore, this project will test the hypothesis that BMEC CXCR2-CXCL1 signaling alters angiogenesis and improves CML LSC maintenance after TKI. It will employ innovative experimental approaches including CITE-seq surface protein and transcript analysis of patient CML samples at the time of stopping TKI, BMEC-stem cell co-cultures, CRISPR-CAS9 deletion of CXCR2, and stem cell transplant assays using novel CXCR2 deletion mouse models to further this goal. These findings will have a significant impact in understanding the direct and indirect effects of BMEC CXCR2 signaling in the pathogenesis and treatment of CML. The proposed training plan is sponsored by Dr. Ravi Bhatia, MD, an established hematologist-oncologist and pioneer of quiescent CML LSC studies. Included in the training plan are experiences that will help Alecia develop in three major areas: 1) rigorous immunology and oncology research, which includes developing familiarity with the existing literature, critical evaluation of data, and training in the responsible conduct of research, 2) opportunities for training in advanced bioinformatics and computational analysis, and 3) career and professional development, including grant and manuscript writing, scientific communications, and the translation of research findings to clinical applications. This proposal drives the development of skills required for rigorous hematological malignancy research, critical immunology and molecular biology techniques, and advanced bioinformatics skills needed for the PI’s future career as a physician-scientist.
