Transforming growth factor-beta(1) augments granulocyte-macrophage colony-stimulating factor-induced proliferation of umbilical cord blood CD34(+) cells with an associated tyrosine phosphorylation of STAT5

• Published in: Experimental hematology 2002-10, Vol.30 (10), p.1132-1138
• Main Authors: Suzuki, Motoyuki, Harashima, Akira, Okochi, Ayumi, Yamamoto, Mayuko, Matsuo, Yoshinobu, Motoda, Ryuichi, Yoshioka, Tamotsu, Orita, Kunzo
• Format: Article
• Language: English
• Subjects: Antigens, CD - blood; Antigens, CD34 - blood; Cell Division - drug effects; DNA-Binding Proteins - drug effects; DNA-Binding Proteins - metabolism; Fetal Blood - cytology; Granulocyte-Macrophage Colony-Stimulating Factor - pharmacology; Hematopoietic Stem Cells - cytology; Hematopoietic Stem Cells - drug effects; Humans; Infant, Newborn; Milk Proteins; Phosphorylation; Phosphotyrosine - metabolism; Recombinant Proteins - pharmacology; STAT5 Transcription Factor; Trans-Activators - drug effects; Trans-Activators - metabolism; Transforming Growth Factor beta - pharmacology
• ISSN: 0301-472X
• DOI: 10.1016/S0301-472X(02)00902-5

Several investigators have reported that transforming growth factor (TGF)-beta(1) and granulocyte-macrophage colony-stimulating factor (GM-CSF) synergistically support cell proliferation. However, the mechanisms involved have not been elucidated. To clarify the mechanisms of the synergistic action of TGF-beta(1) and GM-CSF, we compared the activation states of STAT5 and mitogen-activated protein kinase in CD34(+) cells and in GM-CSF-dependent hematopoietic cell lines. Human CD34(+) cells and GM-CSF-dependent cell lines (FKH-1, YNH-1, and M-07e) were stimulated with 1.25 ng/mL GM-CSF and/or 0.25 ng/mL TGF-beta(1), and 1.25 ng/mL GM-CSF and/or 0.25 ng/mL, 0.025 ng/mL TGF-beta(1), respectively, and cell proliferation was analyzed by [3H]thymidine uptake. Expression of signal transduction proteins and their phosphorylation states were determined by Western blotting. TGF-beta(1) synergistically enhanced the GM-CSF-augmented growth of CD34(+) cells and FKH-1 cells, but inhibited the growth of YNH-1 and M-07e cells. Tyrosine phosphorylation of STAT5 induced by GM-CSF was enhanced by stimulation with the combination of TGF-beta(1) and GM-CSF (TGF-beta(1)/GM-CSF) compared with that induced by GM-CSF alone in CD34(+) cells and FKH-1 cells. However, combinations of TGF-beta(1)/GM-CSF caused inhibition of GM-CSF-induced tyrosine phosphorylation in M-07e cells. No significant difference was observed in mitogen-activated protein kinase activation between CD34(+) cells and FKH-1 cells stimulated with GM-CSF/TGF-beta(1) or GM-CSF alone. Results suggest that TGF-beta(1) may augment GM-CSF-induced proliferation of CD34(+) cells in association with enhanced tyrosine phosphorylation of STAT5. Our data suggest a novel mechanism for the synergistic enhancement of cellular growth induced by the combination of TGF-beta(1) and GM-CSF.