Oncogenic KIT mutations induce STAT3-dependent autophagy to support cell proliferation in acute myeloid leukemia.

Autophagy is associated with both survival and cell death in myeloid malignancies. Therefore, deciphering its role in different genetically defined subtypes of acute myeloid leukemia (AML) is critical. Activating mutations of the KIT receptor tyrosine kinase are frequently detected in core-binding factor AML and are associated with a greater risk of relapse. Herein, we report that basal autophagy was significantly increased by the KIT mutation in AML cells and contributed to support their cell proliferation and survival. Invalidation of the key autophagy protein Atg12 strongly reduced tumor burden and improved survival of immunocompromised NSG mice engrafted with KIT TF-1 cells. Downstream of KIT, STAT3, but not AKT or ERK pathways, was identified as a major regulator of autophagy. Accordingly, STAT3 pharmacological inhibition or downregulation inhibited autophagy and reduced tumor growth both in vitro and in vivo. Taken together, our results support the notion that targeting autophagy or STAT3 opens up an exploratory pathway for finding new therapeutic opportunities for patients with CBF-AML or others malignancies with KIT mutations.