1. Synergistic differentiation-promoting activity of interferon gamma and tumor necrosis factor-alpha: role of receptor regulation on human neuroblasts.
- Author
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Montaldo PG, Carbone R, Corrias MV, Ferraris PC, and Ponzoni M
- Subjects
- Base Sequence, Drug Synergism, Humans, Molecular Sequence Data, Polymerase Chain Reaction, Recombinant Proteins pharmacology, Tumor Cells, Cultured, Interferon-gamma pharmacology, Neuroblastoma metabolism, Receptors, Interferon drug effects, Receptors, Tumor Necrosis Factor drug effects, Tumor Necrosis Factor-alpha pharmacology
- Abstract
Background: Interferon gamma (IFN-gamma) and tumor necrosis factor-alpha (TNF) synergize in inducing human neuroblastoma cells to differentiate terminally in vitro into mature nonproliferating neurons. The mechanisms by which this synergistic activity takes place are still obscure., Purpose: To understand the basis of IFN-gamma-TNF synergism, we investigated the constitutive equipment of receptors to IFN-gamma and TNF in two human neuroblastoma cell lines (i.e., LAN-5 and GI-LI-N) and their quantitative and functional variations following treatment with IFN-gamma or TNF., Methods: IFN-gamma receptors and TNF receptors were assessed and functionally characterized by radioreceptor-binding assay before and after treatment of the cells with IFN-gamma or TNF. The TNF receptor subtypes were identified by the reverse transcriptase-polymerase chain reaction, chemical cross-linking of receptors to iodinated TNF, and inhibition of TNF binding by type-specific anti-TNF receptor monoclonal antibodies. The effects of cytokines on cell differentiation were assessed by thymidine incorporation inhibition and morphologic maturation., Results: No quantitative or functional modification of IFN-gamma receptors was observed in TNF-treated cells. However, after treatment with IFN-gamma, TNF receptor numbers were enhanced to a different extent in both cell lines. The two neuroblastoma cell lines expressed, both constitutively and after IFN-gamma induction, only one species of TNF receptor, i.e., the p80 form in LAN-5 and the p60 form in GI-LI-N. Sequential treatment with IFN-gamma followed by TNF, but not in the opposite order, could reproduce the early effects of differentiation in neuroblastoma cells, supporting a role for TNF receptor up-regulation as a basis for the cooperation between the two cytokines., Conclusion: The results strongly suggest that receptor regulation can be at least one mechanism by which IFN-gamma and TNF exert their synergistic effects. Moreover, it appears that the two TNF receptor types are redundant in signaling neuroblastoma cell differentiation., Implications: Our findings can provide a guideline for a rational design of experimental differentiation-based therapeutic protocols in patients with neuroblastoma. more...
- Published
- 1994
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