Constitutive and specific activation of STAT3 by BCR-ABL in embryonic stem cells.
BCR-ABL oncogene, the molecular hallmark of chronic myelogenous leukemia (CML) arises in a primitive hematopoietic stem cell with both differentiation and self-renewal ability. To study the phenotypic effects of BCR-ABL in a clonal in vitro self-renewal and differentiation model, we have introduced BCR-ABL in the ES cell line CCE. The major effect of BCR-ABL expression was the persistence of primitive morphology of ES cells despite LIF deprivation, correlated with a constitutive activation of STAT3, the major self-renewal factor of ES cells, but no evidence of activation of STAT5. The enforced expression of BCR-ABL in an ES cell line, engineered to express a tetracycline-inducible dominant-negative form of a STAT3, triggered ES cell differentiation with an increased generation of hematopoietic cells expressing erythroid and megakaryocytic phenotypes. RT-PCR analysis for Oct4, Brachyury and beta-globin expression confirmed a delay of differentiation in BCR-ABL expressing clones, which could be entirely reversed upon activation of the dominant-negative form of STAT3. To study the possible relevance of STAT3 activation by BCR-ABL in human CML, Western blot analyses performed on the CD34+ cells, purified from CML patients at different stages of their disease, also demonstrated increased levels of STAT3 proteins phosphorylated both on tyrosine and serine residues. These results represent to our knowledge the first functional link between BCR-ABL oncogene and a self-renewal in the context of ES cells through constitutive activation of STAT3. Thus, the BCR-ABL embryonic stem cell model that we developed as well as the results obtained in human CML samples suggests a role for STAT3 in the pathogenesis of human CML.
Coppo
Paul
P
INSERM U362, Translational Research-Cell Therapy Laboratory, Villejuif, Cedex, France.
Dusanter-Fourt
Isabelle
I
Millot
Gael
G
Nogueira
Maria Manuela
MM
Dugray
Aymeric
A
Bonnet
Marie Laure
ML
Mitjavila-Garcia
Maria Theresa
MT
Le Pesteur
Dominique
D
Guilhot
Francosie
F
Vainchenker
William
W
Sainteny
Francoise
F
Turhan
Ali G
AG
D018952:Antigens, CD34 / Q000096:biosynthesis; D015153:Blotting, Western; D002454:Cell Differentiation; D002460:Cell Line; D019070:Cell Lineage; D004268:DNA-Binding Proteins / Q000378:metabolism*; D004622:Embryo, Mammalian / Q000166:cytology*; D005326:Fetal Proteins; D005434:Flow Cytometry; D016044:Fusion Proteins, bcr-abl / Q000378:metabolism*; D018014:Gene Transfer Techniques; D005799:Genes, Dominant; D005914:Globins / Q000378:metabolism; D006412:Hematopoietic Stem Cells / Q000378:metabolism; D006801:Humans; D015464:Leukemia, Myelogenous, Chronic, BCR-ABL Positive / Q000378:metabolism; D008894:Milk Proteins; D050814:Octamer Transcription Factor-3; D010641:Phenotype; D010766:Phosphorylation; D016133:Polymerase Chain Reaction; D020133:Reverse Transcriptase Polymerase Chain Reaction; D050796:STAT3 Transcription Factor; D050799:STAT5 Transcription Factor; D013234:Stem Cells / Q000378:metabolism*; D020825:T-Box Domain Proteins / Q000378:metabolism; D013997:Time Factors; D015534:Trans-Activators / Q000378:metabolism*; D014157:Transcription Factors; D000098908:Brachyury Protein
D018952:Antigens, CD34; D004268:DNA-Binding Proteins; D005326:Fetal Proteins; D016044:Fusion Proteins, bcr-abl; D005914:Globins; D008894:Milk Proteins; D050814:Octamer Transcription Factor-3; D050796:STAT3 Transcription Factor; D050799:STAT5 Transcription Factor; D020825:T-Box Domain Proteins; D015534:Trans-Activators; D014157:Transcription Factors; D000098908:Brachyury Protein; C494173:POU5F1 protein, human; C494086:STAT3 protein, human