Chaperone -mediated autophagy maintains leukemic stem cells

Acute myeloid leukemia (AML) is a clinically and molecularly heterogeneous group of mostly incurable hematologic malignancies driven by transformed stem cells (leukemic stem cells, LSC) endowed with enhanced self-renewal capacity and blocked myeloid differentiation. Insights into pathways of LSC maintenance will provide key targets for curative therapies. We have previously shown that chaperone-mediated autophagy (CMA) is essential for metabolic adaptation in HSC to regenerative stress (Dong et al., Nature 2021). To test the relevance of CMA in LSC, we developed new mouse models of AML with concomitant CMA deficiency through conditionally deleting (Vav-iCre driven) Lysosome-associated membrane protein 2 (Lamp2a, L2A) which is specific and rate-limiting for this autophagy pathway. We characterized self-renewal and myeloid differentiation potential of leukemia cells upon L2A deletion by gold-standard serial ex vivo colony assays and in vivo bone marrow transplantation assays. Our data thus far have revealed that CMA blockade causes compromised ex vivo self-renewal of LSC and significantly prolongs survival of recipients upon adoptive cell transfer compared to L2AWT controls, consistent with compromised LSC maintenance. Moreover, CMA deficient LSC presented with significantly increased myeloid differentiation compared to CMA competent LSC, suggesting that CMA impacts molecular pathways that favor self-renewal over differentiation commitment. We are currently building precise humanized models and employ degron-mediated ablation of L2A to test the consequences of CMA ablation in human AML. If successful, our study will provide exciting preclinical rationales for the testing of CMA inhibitors for eradication of LSC, particularly alongside current mainstay therapies, as a novel and potential curative option for patients with myeloid malignancies. Acute myeloid leukemia (AML) is a clinically and molecularly heterogeneous group of mostly incurable hematologic malignancies driven by transformed stem cells (leukemic stem cells, LSC) endowed with enhanced self-renewal capacity and blocked myeloid differentiation. Insights into pathways of LSC maintenance will provide key targets for curative therapies. We have previously shown that chaperone-mediated autophagy (CMA) is essential for metabolic adaptation in HSC to regenerative stress (Dong et al., Nature 2021). To test the relevance of CMA in LSC, we developed new mouse models of AML with concomitant CMA deficiency through conditionally deleting (Vav-iCre driven) Lysosome-associated membrane protein 2 (Lamp2a, L2A) which is specific and rate-limiting for this autophagy pathway. We characterized self-renewal and myeloid differentiation potential of leukemia cells upon L2A deletion by gold-standard serial ex vivo colony assays and in vivo bone marrow transplantation assays. Our data thus far have revealed that CMA blockade causes compromised ex vivo self-renewal of LSC and significantly prolongs survival of recipients upon adoptive cell transfer compared to L2AWT controls, consistent with compromised LSC maintenance. Moreover, CMA deficient LSC presented with significantly increased myeloid differentiation compared to CMA competent LSC, suggesting that CMA impacts molecular pathways that favor self-renewal over differentiation commitment. We are currently building precise humanized models and employ degron-mediated ablation of L2A to test the consequences of CMA ablation in human AML. If successful, our study will provide exciting preclinical rationales for the testing of CMA inhibitors for eradication of LSC, particularly alongside current mainstay therapies, as a novel and potential curative option for patients with myeloid malignancies.