Nitric oxide-mediated modulation of interleukin-8 production by a human glioblastoma cell line, T98G, cocultured with myeloid and monocytic cell lines.
Coculture of T98G glioblastoma cells with the myeloid and monocytic cell lines, HL-60, and THP-1 produced minimal amounts of interleukin-8 (IL-8). Pretreatment of HL-60 or THP-1 cells with phorbol myristate acetate (PMA) enhanced their capacity to induce IL-8 production by T98G cells. In contrast, the murine macrophage cell lines J774 A.1 and RAW 264.7 induced high levels of IL-8 production by T98G cells without PMA activation. To determine the molecules responsible for the induction of IL-8 by T98G cells, we carried out coculture experiments with a membrane fraction prepared from RAW cells and indicated that membrane-associated and free forms of murine IL-1alpha acted on human T98G cells to produce IL-8. RAW cells were unique in that increasing the number of RAW cells relative to the number of T98G cells (RAW/T98G ratio > 4:1) significantly suppressed IL-8 production by T98G cells. Because RAW cells produce large amounts of nitric oxide (NO), we assumed that the suppression of IL-8 production was ascribable to the NO produced by the RAW cells. This was supported by the inverse relationship between increasing concentrations of NO and IL-8 production seen in this coculture system. The involvement of NO in the suppression of IL-8 production was confirmed by the finding that N-monomethyl-L-arginine (NMMA), which inhibits NO production, reversed this suppression, whereas S-nitroso-N-acetyl-D,L-penicillamine (SNAP), a strong NO generator, suppressed IL-8 production. Our results indicate that high levels of NO suppress IL-8 production by T98G cells, and murine IL-1alpha plays a major role in the induction of IL-8 production by T98G cells. It is, therefore, possible that excessive production of NO during the interaction of glioma cells with macrophages may play a regulatory role in chemokine production, thus mitigating inflammatory responses.
Oda
T
T
Department of Biochemistry, Kyoritsu College of Pharmacy, Tokyo, Japan.
Kasahara
T
T
Matsuura
M
M
Mukaida
N
N
D000818:Animals; D002460:Cell Line; D018920:Coculture Techniques; D005909:Glioblastoma / Q000378:metabolism / Q000503:physiopathology*; D018922:HL-60 Cells; D006801:Humans; D016209:Interleukin-8 / Q000096:biosynthesis*; D008264:Macrophages / Q000187:drug effects; D051379:Mice; D009000:Monocytes / Q000378:metabolism*; D009569:Nitric Oxide / Q000502:physiology*; D010396:Penicillamine / Q000031:analogs & derivatives / Q000494:pharmacology; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D014407:Tumor Cells, Cultured; D019323:omega-N-Methylarginine / Q000494:pharmacology
D016209:Interleukin-8; C110881:S-nitro-N-acetylpenicillamine; D019323:omega-N-Methylarginine; D009569:Nitric Oxide; D010396:Penicillamine; D013755:Tetradecanoylphorbol Acetate