Microarray data of human MLLr AML cells with or without CD93 expression

Leukemia stem cells (LSCs) share several crucial properties with hematopoietic stem cells (HSCs) including self-renewal, cell cycle quiescence, and expression of a CD34+CD38- immunophenotype, which complicates efforts to eradicate AML by therapeutically targeting LSCs without adversely affecting HSCs. Here we report that CD93, a C-type lectin transmembrane receptor, is preferentially expressed on the cell surface of LSCs compared with HSCs in the genetic subtype of AML with genomic rearrangements of the MLL gene. LSCs that selectively express CD93 are actively cycling, and highly enriched for xeno-engraftment potential, yet comprise a minor component of an otherwise quiescent CD34+CD38- compartment of human AML. Notably, CD93 is required for LSC function in MLL leukemogenesis, and is not simply a passive surface marker co-expressed on LSCs. Thus, CD93 selectively marks and essentially maintains LSCs, and identifies them as predominantly cycling, non-quiescent leukemia-initiating cells in MLL-rearranged AML. Comparison of gene expression profiles of the LSC-enriched (CD34+CD38-CD93+) versus LSC-depleted (CD34+CD38-CD93-) populations from within individual MLLr leukemias