Granulocyte-macrophage progenitors as candidate leukemic stem cells in blast-crisis CML.
BACKGROUND
The progression of chronic myelogenous leukemia (CML) to blast crisis is supported by self-renewing leukemic stem cells. In normal mouse hematopoietic stem cells, the process of self-renewal involves the beta-catenin-signaling pathway. We investigated whether leukemic stem cells in CML also use the beta-catenin pathway for self-renewal.


METHODS
We used fluorescence-activated cell sorting to isolate hematopoietic stem cells, common myeloid progenitors, granulocyte-macrophage progenitors, and megakaryocyte-erythroid progenitors from marrow during several phases of CML and from normal marrow. BCR-ABL, beta-catenin, and LEF-1 transcripts were compared by means of a quantitative reverse-transcriptase-polymerase-chain-reaction assay in normal and CML hematopoietic stem cells and granulocyte-macrophage progenitors. Confocal fluorescence microscopy and a lymphoid enhancer factor/T-cell factor reporter assay were used to detect nuclear beta-catenin in these cells. In vitro replating assays were used to identify self-renewing cells as candidate leukemic stem cells, and the dependence of self-renewal on beta-catenin activation was tested by lentiviral transduction of hematopoietic progenitors with axin, an inhibitor of the beta-catenin pathway.


RESULTS
The granulocyte-macrophage progenitor pool from patients with CML in blast crisis and imatinib-resistant CML was expanded, expressed BCR-ABL, and had elevated levels of nuclear beta-catenin as compared with the levels in progenitors from normal marrow. Unlike normal granulocyte-macrophage progenitors, CML granulocyte-macrophage progenitors formed self-renewing, replatable myeloid colonies, and in vitro self-renewal capacity was reduced by enforced expression of axin.


CONCLUSIONS
Activation of beta-catenin in CML granulocyte-macrophage progenitors appears to enhance the self-renewal activity and leukemic potential of these cells.
Division of Hematology, Stanford University School of Medicine, Stanford, Calif 94305-5323, USA.
Catriona H M
CH
Jamieson
Laurie E
LE
Ailles
Scott J
SJ
Dylla
Manja
M
Muijtjens
Carol
C
Jones
James L
JL
Zehnder
Jason
J
Gotlib
Kevin
K
Li
Markus G
MG
Manz
Armand
A
Keating
Charles L
CL
Sawyers
Irving L
IL
Weissman
D000328:Adult; D000368:Aged; D000970:Antineoplastic Agents / Q000627:therapeutic use; D001549:Benzamides; D001752:Blast Crisis / Q000503:physiopathology*; D003114:Colony-Forming Units Assay; D003598:Cytoskeletal Proteins / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000378:metabolism; D019008:Drug Resistance, Neoplasm; D005260:Female; D016044:Fusion Proteins, bcr-abl / Q000378:metabolism; D006098:Granulocytes / Q000166:cytology; D006412:Hematopoietic Stem Cells / Q000378:metabolism / Q000502:physiology*; D006801:Humans; D000068877:Imatinib Mesylate; D015464:Leukemia, Myelogenous, Chronic, BCR-ABL Positive / Q000188:drug therapy / Q000378:metabolism / Q000503:physiopathology*; D051821:Lymphoid Enhancer-Binding Factor 1; D008264:Macrophages / Q000166:cytology; D008297:Male; D018613:Microscopy, Confocal; D008875:Middle Aged; D010879:Piperazines / Q000627:therapeutic use; D011743:Pyrimidines / Q000627:therapeutic use; D012334:RNA, Neoplasm; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015534:Trans-Activators / Q000378:metabolism*; D014157:Transcription Factors / Q000378:metabolism; D051176:beta Catenin
D000970:Antineoplastic Agents; D001549:Benzamides; C495270:CTNNB1 protein, human; D003598:Cytoskeletal Proteins; D004268:DNA-Binding Proteins; C497573:LEF1 protein, human; D051821:Lymphoid Enhancer-Binding Factor 1; D010879:Piperazines; D011743:Pyrimidines; D012334:RNA, Neoplasm; D015534:Trans-Activators; D014157:Transcription Factors; D051176:beta Catenin; D000068877:Imatinib Mesylate; D016044:Fusion Proteins, bcr-abl