Quentmeier H, Dirks WG, Fleckenstein D, Zaborski M, Drexler HG. Tumor necrosis factor-alpha-induced proliferation requires synthesis of granulocyte-macrophage colony-stimulating factor.
Exp Hematol 2000;
28:1008-15. [PMID:
11008013 DOI:
10.1016/s0301-472x(00)00516-6]
[Citation(s) in RCA: 15] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
OBJECTIVE
Tumor necrosis factor- alpha (TNF-alpha) induces a variety of cellular responses, some of them being at least seemingly contradictory. Thus, we set out to find differences in the modes of proliferative and apoptotic responses to TNF- alpha.
MATERIALS AND METHODS
We screened a panel of acute myeloid leukemia-derived cell lines for TNF- alpha-responsiveness. In two lines (OCI-AML-1, OCI-AML-11), TNF- alpha acted as an apoptotic agent; in others (HU-3, M-07e, TF-1), it had the opposite effect, preventing apoptosis and inducing proliferation. Direct and indirect signaling mechanisms, including NF-kappaB activation and cytokine synthesis, were analyzed.
RESULTS
All cell lines tested expressed TNF- alpha receptors I and II and responded to TNF- alpha by upregulation of intercellular adhesion molecule-1. In contrast to granulocyte-macrophage colony-stimulating factor (GM-CSF), TNF- alpha did not activate the MAP kinase and p70S6 kinase pathways. Nevertheless, inhibitors of these pathways clearly reduced the TNF-alpha-induced cell growth, indicating that TNF- alpha-proliferative cells produced a growth factor that induced proliferation upon stimulation of the above pathways. Anti-GM-CSF antibodies inhibited the TNF-alpha-induced growth, suggesting the presence of an autocrine loop for cell proliferation mediated by GM-CSF. Supporting this notion, TNF-alpha-induced upregulation of GM-CSF mRNA levels and protein secretion in the TNF-alpha-proliferative, but not in the TNF-alpha-apoptotic cell lines.
CONCLUSION
These data identify GM-CSF synthesis as an early and essential step in TNF- alpha-induced proliferation. We show for the first time that TNF-alpha-treated cell lines producing no or only minimal amounts of GM-CSF demonstrate an apoptotic phenotype, while cell lines with high GM-CSF expression rates can escape from growth arrest or even apoptosis. In this context, we discuss arguments pointing at NF-kappaB as regulator of GM-CSF synthesis and thus indirectly as regulator for the escape of TNF-alpha-induced apoptosis.
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