title: Role of the p38 mitogen-activated protein kinase pathway in cytokine-mediated hematopoietic suppression in myelodysplastic syndromes.
abstract: The p38 mitogen-activated protein kinase (MAPK) pathway is activated by IFNs and other cytokines to mediate signals for important cellular functions, including transcriptional regulation and apoptosis. We examined the role of the p38 pathway in the generation of the effects of myelosuppressive cytokines on human hematopoiesis. Pharmacologic inhibition of p38 using BIX-01208 resulted in reversal of IFN-, tumor necrosis factor-alpha (TNF-alpha)-, and transforming growth factor-beta (TGF-beta)-mediated suppression of human erythroid (blast-forming unit-erythroid) and myeloid (granulocyte-macrophage colony-forming unit) colony formation, consistent with a key role for p38 in the generation of myelosuppressive signals by different cytokines. Similarly, the myelosuppressive effects of TNF-alpha and TGF-beta were reversed by small interfering RNAs targeting p38alpha expression, further establishing the requirement of this kinase in the induction of myelosuppressive responses. As TNF overproduction has been implicated in the pathophysiology of bone marrow failure states, we determined whether pharmacologic inhibition of p38 reverses the hematopoietic defects seen in bone marrows from patients with myelodysplastic syndromes (MDS) and the anemia of chronic disease. Addition of pharmacologic inhibitors of p38 on such bone marrows resulted in increased numbers of erythroid and myeloid progenitors. Similarly, inhibition of the activity of the downstream effectors of p38, MAPK activated protein kinase-2, and mitogen and stress activated kinase 1 partially restored the hematopoietic defect seen in these bone marrows. Taken altogether, our data implicate the p38 MAPK in the pathophysiology of myelodysplasias and suggest that p38 pharmacologic inhibitors may have therapeutic applications in the treatment of MDS.
authors.affiliation: Robert H. Lurie Comprehensive Cancer Center and Division of Hematology-Oncology, Northwestern University Medical School, Chicago, IL 60611, USA.
authors.forename: Efstratios
authors.initials: E
authors.lastname: Katsoulidis
authors.forename: Yongzhong
authors.initials: Y
authors.lastname: Li
authors.forename: Patrick
authors.initials: P
authors.lastname: Yoon
authors.forename: Antonella
authors.initials: A
authors.lastname: Sassano
authors.forename: Jessica
authors.initials: J
authors.lastname: Altman
authors.forename: Padma
authors.initials: P
authors.lastname: Kannan-Thulasiraman
authors.forename: Lakshmi
authors.initials: L
authors.lastname: Balasubramanian
authors.forename: Simrit
authors.initials: S
authors.lastname: Parmar
authors.forename: John
authors.initials: J
authors.lastname: Varga
authors.forename: Martin S
authors.initials: MS
authors.lastname: Tallman
authors.forename: Amit
authors.initials: A
authors.lastname: Verma
authors.forename: Leonidas C
authors.initials: LC
authors.lastname: Platanias
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000911:Antibodies, Monoclonal / Q000276:immunology / Q000494:pharmacology; D005260:Female; D006412:Hematopoietic Stem Cells / Q000201:enzymology* / Q000276:immunology / Q000473:pathology; D006801:Humans; D007371:Interferon-gamma / Q000276:immunology / Q000494:pharmacology; D020935:MAP Kinase Signaling System / Q000187:drug effects / Q000502:physiology*; D008297:Male; D008875:Middle Aged; D009190:Myelodysplastic Syndromes / Q000201:enzymology* / Q000235:genetics / Q000276:immunology / Q000473:pathology; D034741:RNA, Small Interfering / Q000235:genetics; D011994:Recombinant Proteins / Q000276:immunology / Q000494:pharmacology; D014162:Transfection; D016212:Transforming Growth Factor beta / Q000276:immunology / Q000494:pharmacology; D014409:Tumor Necrosis Factor-alpha / Q000276:immunology / Q000494:pharmacology; D048051:p38 Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*
chemical_list: D000911:Antibodies, Monoclonal; D034741:RNA, Small Interfering; D011994:Recombinant Proteins; D016212:Transforming Growth Factor beta; D014409:Tumor Necrosis Factor-alpha; D007371:Interferon-gamma; D048051:p38 Mitogen-Activated Protein Kinases