Transforming growth factor-beta1 interferes with thrombopoietin-induced signal transduction in megakaryoblastic and erythroleukemic cells

Exp Hematol. 2001 May;29(5):602-8. doi: 10.1016/s0301-472x(01)00628-2.

Abstract

Objective: Thrombopoietin (TPO) and transforming growth factor-beta(1) (TGF-beta(1)) have been shown to exert opposite effects on proliferation and megakaryocytic differentiation of hematopoietic cells. To determine whether TGF-beta(1) interferes directly with TPO-induced signal transduction in hematopoietic cells, we compared the regulatory effects in the TPO-responsive cell lines Mo-7e and HEL.

Materials and methods: The cells were stimulated by 100 ng/mL TPO and/or 100 ng/mL TGF-beta1 and analyzed for proliferation (3H thymidine incorporation), viability (trypan blue exclusion), and protein expression and phosphorylation (Western blot).

Results: TPO enhanced the proliferation of Mo-7e cells as determined by 3H-thymidine incorporation, whereas TGF-beta1 suppressed baseline cell growth and antagonized the proliferative effect of TPO. TPO-induced proliferation also was reduced by a specific inhibitor of the mitogen-activated protein kinase (MAPK) pathway (PD098059), which inhibits activation of the MAPK extracellular signal-regulated kinases (ERK) ERK1 and ERK2, and AG490, an inhibitor of Janus kinase-2, which completely blocked TPO-induced proliferation. As demonstrated by Western blotting, TGF-beta1 reduced the TPO-stimulated ERK1/ERK2 and STAT5 phosphorylation in Mo-7e and HEL cells. This effect was completely reversed by preincubation with a tyrosine phosphatase inhibitor (Na3VO4), which suggests that TGF-beta1 activated a phosphatase. Although STAT3 also was activated by TPO, STAT3 activation remained unaltered by TGF-beta1.

Conclusion: Taken together, these data suggest that TGF-beta1 modulates TPO-mediated effects on megakaryocytic proliferation by interfering with TPO-induced signal transduction, particularly by reducing the activities of MAPK ERK1/ERK2 and STAT5.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Cell Differentiation / drug effects
  • Cell Division / drug effects
  • DNA-Binding Proteins / antagonists & inhibitors
  • DNA-Binding Proteins / metabolism
  • Enzyme Activation / drug effects
  • Enzyme Inhibitors / pharmacology
  • Erythroid Precursor Cells / drug effects*
  • Flavonoids / pharmacology
  • Humans
  • Janus Kinase 2
  • Leukemia, Erythroblastic, Acute / pathology*
  • Leukemia, Megakaryoblastic, Acute / pathology
  • MAP Kinase Signaling System / drug effects*
  • Megakaryocytes / drug effects*
  • Milk Proteins*
  • Mitogen-Activated Protein Kinase 1 / antagonists & inhibitors
  • Mitogen-Activated Protein Kinase 1 / metabolism
  • Mitogen-Activated Protein Kinase 3
  • Mitogen-Activated Protein Kinases / antagonists & inhibitors
  • Mitogen-Activated Protein Kinases / metabolism
  • Neoplasm Proteins / antagonists & inhibitors
  • Neoplasm Proteins / metabolism
  • Neoplastic Stem Cells / drug effects*
  • Protein Tyrosine Phosphatases / antagonists & inhibitors
  • Protein-Tyrosine Kinases / antagonists & inhibitors
  • Protein-Tyrosine Kinases / metabolism
  • Proto-Oncogene Proteins*
  • STAT3 Transcription Factor
  • STAT5 Transcription Factor
  • Thrombopoietin / antagonists & inhibitors*
  • Trans-Activators / antagonists & inhibitors
  • Trans-Activators / metabolism
  • Transforming Growth Factor beta / pharmacology*
  • Transforming Growth Factor beta1
  • Tyrphostins / pharmacology
  • Vanadates / pharmacology

Substances

  • DNA-Binding Proteins
  • Enzyme Inhibitors
  • Flavonoids
  • Milk Proteins
  • Neoplasm Proteins
  • Proto-Oncogene Proteins
  • STAT3 Transcription Factor
  • STAT3 protein, human
  • STAT5 Transcription Factor
  • TGFB1 protein, human
  • Trans-Activators
  • Transforming Growth Factor beta
  • Transforming Growth Factor beta1
  • Tyrphostins
  • alpha-cyano-(3,4-dihydroxy)-N-benzylcinnamide
  • Vanadates
  • Thrombopoietin
  • Protein-Tyrosine Kinases
  • JAK2 protein, human
  • Janus Kinase 2
  • Mitogen-Activated Protein Kinase 1
  • Mitogen-Activated Protein Kinase 3
  • Mitogen-Activated Protein Kinases
  • Protein Tyrosine Phosphatases
  • 2-(2-amino-3-methoxyphenyl)-4H-1-benzopyran-4-one