Identification and Purification of Leukemic Stem-Like Cells in Acute Myeloid Leukemia Cell Line

Acute myeloid leukemia (AML) is initiated and maintained by a rare population of (leukemic stem cells) LSCs. LSCs play the central role in the relapse and refractory of AML and highlight the critical need for the new therapeutic strategies to directly target the LSC population for ultimately curing leukemia which is it is important to identify and study LSCs. However, relatively little is known about the unique molecular mechanisms of survival and self-renewal of LSCs because of very small number of LSCs in bone marrow. In this study, we investigated whether established leukemia cell lines contain LSCs. We showed that leukemia cell line contain leukemic stem-like cells which have been phenotypically restricted within the CD34⁺CD38⁻ fraction. We demonstrated that CD34⁺CD38⁻ cells could generate CD34⁺CD38⁺ cells in culture medium and had proliferation function. Moreover, CD34⁺CD38⁻ cells had self-renewal potential both in vitro soft agar colonies formation assay and in vivo NOD/SCID mouse xenotransplant model serial transplantation. Furthermore, CD34⁺CD38⁻ cells isolated from leukemia cell line were found resistant to conventional chemotherapy and NK cells-mediated cytotoxicity and these were related to up-regulation of ABCG2 and MRP-1 and antiapoptotic proteins of Bcl2. Down-regulation of NKG2D ligand also played a critical role in NK cytotoxicity resistance. Taken together, our studies provide a novel cell model for leukemic stem cells research. Our data also shed light on mechanism of double resistant to resistant to chemotherapy and NK cell immunotherapy, which was helpful for developing novel effective strategies for LSCs.