title: Bcr-Abl-mediated suppression of normal hematopoiesis in leukemia.
abstract: A variety of experimental evidence including findings in various mouse models indicates that the BCR-ABL oncogene is the cause of chronic myeloid leukemia (CML). Since normal hematopoietic cells in marrow and spleen are replaced with proliferating leukemic blasts, we determined whether this is an active process mediated by the leukemia cells. The lipocalin 24p3 was reported to be secreted by mouse hematopoietic cells deprived of IL-3, resulting in apoptosis induction in a variety of hematopoietic cells including bone marrow cells. Here, we show that BCR-ABL+ mouse hematopoietic cells induced persistent expression and secretion of 24p3. Importantly, BCR-ABL+ hematopoietic cells were resistant to the apoptotic effects of 24p3. The expression of the Bcr-Abl oncoprotein and its tyrosine kinase were required for induction of 24p3 expression. Co-culture studies showed that BCR-ABL+ cells induced apoptosis in BCR-ABL negative cells. Antisense 24p3/siRNA expression reduced the level of 24p3 protein in both BCR-ABL+ cells and in conditioned medium (CM) obtained from these cells. CM from BCR-ABL+ cells expressing antisense 24p3/siRNA had reduced apoptotic activity for target cells; 24p3 antibody also reduced the apoptotic activity of the CM. Leukemic mice induced by BCR-ABL+ cells expressing either antisense 24p3 or 24p3 siRNA had increased levels of normal hematopoiesis and reduced invasion of leukemia cells in marrow and spleen tissues. These findings indicate that suppression of normal hematopoiesis in BCR-ABL-induced leukemia is an active process involving secretion of the cell death-inducing factor 24p3 by mouse leukemia cells, raising the possibility that similar factors are involved in BCR-ABL+ CML.
authors.affiliation: Department of Molecular Pathology, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA.
authors.forename: Hui
authors.initials: H
authors.lastname: Lin
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Monaco
authors.forename: Tong
authors.initials: T
authors.lastname: Sun
authors.forename: Xiaoyang
authors.initials: X
authors.lastname: Ling
authors.forename: Clifton
authors.initials: C
authors.lastname: Stephens
authors.forename: Shanhai
authors.initials: S
authors.lastname: Xie
authors.forename: John
authors.initials: J
authors.lastname: Belmont
authors.forename: Ralph
authors.initials: R
authors.lastname: Arlinghaus
mesh_terms: D000209:Acute-Phase Proteins / Q000502:physiology*; D000818:Animals; D017209:Apoptosis; D015153:Blotting, Western; D001854:Bone Marrow Cells / Q000378:metabolism; D016923:Cell Death; D018920:Coculture Techniques; D004305:Dose-Response Relationship, Drug; D016044:Fusion Proteins, bcr-abl / Q000378:metabolism / Q000502:physiology*; D006410:Hematopoiesis / Q000502:physiology*; D006412:Hematopoietic Stem Cells / Q000378:metabolism; D006801:Humans; D007377:Interleukin-3 / Q000378:metabolism; D016086:Lentivirus / Q000235:genetics; D007938:Leukemia / Q000378:metabolism; D015464:Leukemia, Myelogenous, Chronic, BCR-ABL Positive / Q000378:metabolism* / Q000473:pathology*; D000071068:Lipocalin-2; D054834:Lipocalins; D051379:Mice; D008809:Mice, Inbred C3H; D016688:Mice, Inbred NOD; D016513:Mice, SCID; D016376:Oligonucleotides, Antisense / Q000494:pharmacology; D015513:Oncogene Proteins / Q000502:physiology*; D010957:Plasmids / Q000378:metabolism; D016133:Polymerase Chain Reaction; D034741:RNA, Small Interfering / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013154:Spleen / Q000378:metabolism; D013752:Tetracycline / Q000494:pharmacology; D013997:Time Factors
chemical_list: D000209:Acute-Phase Proteins; D007377:Interleukin-3; D000071068:Lipocalin-2; D054834:Lipocalins; D016376:Oligonucleotides, Antisense; D015513:Oncogene Proteins; D034741:RNA, Small Interfering; C071332:Lcn2 protein, mouse; D016044:Fusion Proteins, bcr-abl; D013752:Tetracycline