title: TGF beta-induced SMAD2 phosphorylation predicts inhibition of thymidine incorporation in CD34+ cells from healthy donors, but not from patients with AML after MDS.
abstract: Cells from patients with MDS-derived AML display heterogeneous proliferative responses to transforming growth factor beta (TGF beta). We analyzed growth inhibition and SMAD2 phosphorylation by TGF beta in CD34+ cells from nine patients, as compared to normal controls. While TGF beta consistently inhibited thymidine incorporation of normal cells (41% of control, P < 0.05), cells from patients with AML were growth-inhibited in only four of seven cases (40%), whereas TGF beta stimulated thymidine incorporation in the three other samples (166%). Remarkably, TPO reverted the stimulatory effect of TGF beta to profound growth inhibition. Upon exposure to TGF beta, SMAD2 protein was phosphorylated in normal CD34+ cells (n = 3), CD34+ leukemic blasts from all examined patients with AML (n = 4), and in the myeloid leukemic cell lines M-07e and HEL. TGF beta inhibited TPO-mediated thymidine incorporation, cell proliferation and survival in all samples analyzed. In M-07e cells and CD34+ cells from healthy donors, this inhibition was enhanced by an antagonist of JAK2 (AG490), but not a MEK-1 antagonist (PD098059). Conversely, in CD34+ cells from a patient with AML, both AG490 and PD098059 significantly enhanced TGF beta-mediated suppression of TPO-induced thymidine incorporation. Thus, in MDS-derived AML, altered responses to TGF beta may be due to defects downstream of SMAD2 and may involve MAPK activation.
authors: Division of Hematology, Department of Internal Medicine III, Johann Wolfgang Goethe University, Frankfurt, Germany.
authors: S
authors: S
authors: Koschmieder
authors: W K
authors: WK
authors: Hofmann
authors: J
authors: J
authors: Kunert
authors: S
authors: S
authors: Wagner
authors: K
authors: K
authors: Ballas
authors: G
authors: G
authors: Seipelt
authors: D
authors: D
authors: Hoelzer
authors: O G
authors: OG
authors: Ottmann
authors: U
authors: U
authors: Kalina
mesh_terms: D000208:Acute Disease; D000328:Adult; D018952:Antigens, CD34 / Q000032:analysis; D002455:Cell Division / Q000187:drug effects; D004261:DNA Replication / Q000187:drug effects*; D004273:DNA, Neoplasm / Q000096:biosynthesis; D004268:DNA-Binding Proteins / Q000378:metabolism*; D018450:Disease Progression; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005419:Flavonoids / Q000494:pharmacology; D006412:Hematopoietic Stem Cells / Q000187:drug effects* / Q000378:metabolism; D006801:Humans; D007377:Interleukin-3 / Q000494:pharmacology; D053614:Janus Kinase 2; D007951:Leukemia, Myeloid / Q000473:pathology*; D048369:MAP Kinase Kinase 1; D020935:MAP Kinase Signaling System / Q000187:drug effects; D020929:Mitogen-Activated Protein Kinase Kinases / Q000037:antagonists & inhibitors; D009190:Myelodysplastic Syndromes / Q000473:pathology*; D009363:Neoplasm Proteins / Q000378:metabolism*; D014411:Neoplastic Stem Cells / Q000187:drug effects* / Q000378:metabolism; D010766:Phosphorylation / Q000187:drug effects; D011499:Protein Processing, Post-Translational / Q000187:drug effects*; D017346:Protein Serine-Threonine Kinases / Q000037:antagonists & inhibitors; D011505:Protein-Tyrosine Kinases / Q000037:antagonists & inhibitors; D011518:Proto-Oncogene Proteins; D020133:Reverse Transcriptase Polymerase Chain Reaction; D051899:Smad2 Protein; D013926:Thrombopoietin / Q000494:pharmacology; D013936:Thymidine / Q000378:metabolism*; D015534:Trans-Activators / Q000378:metabolism*; D016212:Transforming Growth Factor beta / Q000494:pharmacology*; D020032:Tyrphostins / Q000494:pharmacology
chemical_list: D018952:Antigens, CD34; D004273:DNA, Neoplasm; D004268:DNA-Binding Proteins; D004791:Enzyme Inhibitors; D005419:Flavonoids; D007377:Interleukin-3; D009363:Neoplasm Proteins; D011518:Proto-Oncogene Proteins; C497782:SMAD2 protein, human; D051899:Smad2 Protein; D015534:Trans-Activators; D016212:Transforming Growth Factor beta; D020032:Tyrphostins; C095512:alpha-cyano-(3,4-dihydroxy)-N-benzylcinnamide; D013926:Thrombopoietin; D011505:Protein-Tyrosine Kinases; C507924:JAK2 protein, human; D053614:Janus Kinase 2; D017346:Protein Serine-Threonine Kinases; D048369:MAP Kinase Kinase 1; C482125:MAP2K1 protein, human; D020929:Mitogen-Activated Protein Kinase Kinases; C093973:2-(2-amino-3-methoxyphenyl)-4H-1-benzopyran-4-one; D013936:Thymidine