Inhibition of the synthesis of eicosanoid-like substances in a human oral cancer cell line by interferon-γ and eicosapentaenoic Acid

The objectives were to examine the production of eicosanoids in a Chinese human oral cancer cell line (OEC-M1) and to test the effects of interferon-γ (IFN-γ), eicosapentaenoic acid (EPA) and enzyme inhibitors on this biosynthesis. The eicosanoids were identified by reverse phase-high performance liquid chromatography. Two predominant peaks appeared in the chromatograms. One compound (P-1) was identified by ultraviolet absorption at a λmax of 278 nm with shoulders at 272 and 284 nm. The other compound (P-2) was identified by ultraviolet absorption at a λmax of 284 nm with shoulders at 278 and 290 nm. The production of P-1 was significantly inhibited by the addition of IFN-γ (200 and 400 U/ml), and EPA (10 to 40 μM). It was only partially inhibited (p<0.05) by indomethacin (INDO) (0.5 and 1μM), nordihydroguaiaretic acid (NDGA) (30 and 60μM/ml), and eicosa-5,8,11,14-tetraynoic acid (ETYA) (20–60μM). It was almost completely inhibited by indomethacin (2 and 3μM), and dexamethasone (0.6 and 6μM). The production of P-2 was almost completely inhibited by IFN-γ (200 and 400 U/ml), and partially inhibited (p<0.05) by EPA (10 and 20μM), NDGA (30 and 60μM), ETYA (20 and 40μM), dexamethasone (0.6 and 6μM). The production of both peaks was significantly reduced by excluding arachidonic acid (AA), and almost completely inhibited by heating at 100°C for 10 min during incubation. These results demonstrate that two eicosanoid-like compounds are synthesized by the OEC-M1 cell line and that their production can be modulated by IFN-γ, EPA, indomethacin, NDGA, ETYA, and dexamethasone.