title: Impaired immunomodulatory function of chronic myeloid leukemia cancer stem cells and the possible mechanism involved in it.
abstract: BACKGROUND
  Cancer stem cells (CSCs) are proposed to persist in tumors as a distinct population and cause relapse and metastasis by giving rise to new tumors. Development of specific therapies targeted at CSCs holds hope for the improvement of survival and quality of life of cancer patients, especially for sufferers of metastatic disease. This is particularly true in chronic myeloid leukemia (CML).
  
  
  METHODS
  In this study, we isolated fetal liver kinase-1-positive (Flk1(+)) cells carrying the BCR/ABL fusion gene from the bone marrow of Philadelphia chromosome-positive (Ph(+)) patients with stem cells property. We examined their biological characteristics as well as immunological function and further detected the possible molecular mechanism involved in the leukemia genesis.
  
  
  RESULTS
  We showed that CML patient-derived Flk1(+)CD31(-)CD34(-) MSCs had normal morphology, phenotype and karyotype but appeared impaired immunomodulatory function. The capacity of Flk1(+)CD31(-)CD34(-) MSCs from CML patients to inhibit T lymphocyte activation and proliferation was impaired in vitro. CML patient-derived MSCs have dampening immunomodulatory functions, suggesting that the dysregulation of hematopoiesis and immune response might originate from MSCs rather than HSCs. These Ph(+) putative CML hemangioblast upregulated TGF-β1 and resultantly activated matrix metalloproteinase-9 (MMP-9) to enhance s-KitL and s-ICAM-1 secretion, which activated c-kit(+) HSCs from the quiescent state to proliferative state. Further studies showed that phosphatidylinositol-3 kinase (PI3K)/Akt/nuclear factor (NF)-κB signaling pathway was involved in CML pathogenesis.
  
  
  CONCLUSIONS
  Flk1(+)CD31(-)CD34(-) MSCs that express BCR/ABL leukemia oncogene are CSCs of CML and they play a critical role in the progression of CML through PI3K/Akt/NF-κB/MMP-9/s-ICAM-1/s-KitL signaling pathway beyond HSCs.
authors.affiliation: Department of Internal Oncology, Institute of Medical Oncology, Beijing Shijitan Hospital, Capital Medical University, Beijing, 100038, People's Republic of China.
authors.forename: Zhu
authors.initials: Z
authors.lastname: Xishan
authors.forename: Zhou
authors.initials: Z
authors.lastname: Xinna
authors.forename: He
authors.initials: H
authors.lastname: Baoxin
authors.forename: Ren
authors.initials: R
authors.lastname: Jun
mesh_terms: D000293:Adolescent; D000328:Adult; D017209:Apoptosis / Q000276:immunology; D016022:Case-Control Studies; D002453:Cell Cycle / Q000276:immunology; D005260:Female; D016313:Genes, abl / Q000276:immunology; D006801:Humans; D020672:I-kappa B Proteins / Q000378:metabolism; D018799:Intercellular Adhesion Molecule-1 / Q000096:biosynthesis / Q000235:genetics; D015464:Leukemia, Myelogenous, Chronic, BCR-ABL Positive / Q000235:genetics / Q000276:immunology* / Q000378:metabolism / Q000473:pathology; D008213:Lymphocyte Activation; D008297:Male; D020780:Matrix Metalloproteinase 9 / Q000096:biosynthesis / Q000235:genetics; D008875:Middle Aged; D016328:NF-kappa B / Q000378:metabolism; D014411:Neoplastic Stem Cells / Q000276:immunology* / Q000473:pathology; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D016315:Proto-Oncogene Proteins c-abl / Q000378:metabolism; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D034622:RNA Interference; D015398:Signal Transduction; D051785:Smad Proteins / Q000378:metabolism; D013601:T-Lymphocytes / Q000276:immunology; D053773:Transforming Growth Factor beta1 / Q000096:biosynthesis / Q000235:genetics; D015854:Up-Regulation; D040301:Vascular Endothelial Growth Factor Receptor-2 / Q000378:metabolism; D055815:Young Adult
chemical_list: D020672:I-kappa B Proteins; C573420:ICAM1 protein, human; D016328:NF-kappa B; D051785:Smad Proteins; D053773:Transforming Growth Factor beta1; D018799:Intercellular Adhesion Molecule-1; D019869:Phosphatidylinositol 3-Kinases; D040301:Vascular Endothelial Growth Factor Receptor-2; D016315:Proto-Oncogene Proteins c-abl; D051057:Proto-Oncogene Proteins c-akt; D020780:Matrix Metalloproteinase 9