Effects of interleukin-1α on arachidonic acid metabolism in human osteosarcoma osteoblastic cells

The effects of interleukin-1α (IL-1α) on arachidonic acid (AA) metabolism were studied in the human osteosarcoma cell lines, G292 and SaOS-2. The cells were prelabeled with ³H-arachidonic acid. Radiolabeled metabolites were measured by reversed-phase high-pressure liquid chromatography with a radioactive detector. Indomethacin inhibited prostaglandin E₂ (PGE₂) production without affecting lipoxygenase (LO) products in G292 cells. In the G292 cells, IL-1α (50 U/ml) induced a 10-fold increase in PGE₂ production at all the incubation times tested, and a significant two-fold increase in 5 hydroxyeicosatetraenoic acid (HETE) formation after 48 h. These effects were not seen in SaOS-2 cells under identical conditions. These results suggest that, although some osteosarcomal cell lines may not respond directly to IL-1 with effects on AA metabolism, the mechanism of its action in others may involve modulation of both cyclooxygenase (CO) and LO pathways.