Sphingosine-1 phosphate receptor 1 (S1PR1) expression maintains stemness of acute myeloid leukemia stem cells.

Acute myeloid leukemia (AML) arises from leukemia stem cells (LSCs) and is maintained by cells which have acquired features of stemness. We compared transcription profiles of AML cells with/without stem cell features defined as in vitro clonogenicity and serial engraftment in immune-deficient mice xenograft model. We used multi-parameter flow cytometry (MPFC) to separate CD34 bone marrow-derived leukemia cells into sphingosine-1 phosphate receptor 1 (S1PR1) and S1PR1 fractions. Cells in the S1PR1 fraction demonstrated significantly higher clonogenicity and higher engraftment potential compared with those in the S1PR1 fraction. In contrast, CD34 bone marrow cells from normal samples showed reduced clonogenicity in the S1PR1 fraction compared with the S1PR1 fraction. Inhibition of S1PR1 expression in an AML cell line reduced the colony-forming potential of KG1 cells. Transcriptomic analyses and rescue experiments indicated PI3K/AKT pathway and MYBL2 are downstream mediators of S1PR1-associated stemness. These findings implicate S1PR1 as a functional biomarker of LSCs and suggest its potential as a therapeutic target in AML treatment.