AML1-ETO-induced FOXO1 activates a self-renewal program in pre-leukemia stem cells

Blocking the self-renewal of pre-leukemia stem cells could prevent AML relapse. In this study we show that FOXO1 is an essential self-renewal factor in leukemic and pre-leukemic cells expressing the t(8;21)-associated oncogene AML1-ETO (AE). FOXO1 is consistently upregulated in t(8;21) AML and functions as a critical oncogenic mediator rather than a tumor suppressor. Expression of FOXO1 in human CD34+ cells promotes a pre-leukemic state, partially phenocopying the cellular and transcriptional effects of AE expression. The DNA binding ability of FOXO1 is essential for these features. AE and FOXO1 co-occupy the majority of their binding sites, whereby FOXO1 binds to multiple crucial self-renewal genes and is required for their activation. In concordance with this observation, loss of FOXO1 inhibits the long-term proliferation and clonogenicity of AE cells. Thus, increased FOXO1 represents a new mechanism for acquiring aberrant self-renewal by pre-leukemia stem cells and provides a novel target for therapeutic intervention. Overall design: AE and FOXO1 ChIP-seq expreiment have been used to study their activates in pre-leukemia stem cells