Forgue M F, Pipy B, Beraud M, Pinelli E, Cambon C, Didier A, Souqual M C, Vandaele J
INSERM, Unité-87, Institut de Physiologie, Université Paul Sabatier, Toulouse, France.
Carcinogenesis. 1991 Mar;12(3):449-57. doi: 10.1093/carcin/12.3.449.
The effect of the carcinogen diethylnitrosamine (DEN) on prostaglandins (PGs), leukotrienes (LTs) and reactive oxygen intermediates production by murine peritoneal macrophages was assessed. In vitro exposure to DEN (0.8, 1.6 and 8 mM) resulted in a dose-dependent stimulation of the PGs and LTs generation by macrophages. DEN-exposed peritoneal macrophages demonstrated enhanced production of arachidonic acid (AA) metabolites following stimulation with 12-O-tetradecanoylphorbol 13-acetate (TPA) as compared to macrophages stimulated with TPA alone. Studies of [3H]AA release from glycerolipids of prelabelled macrophages and of the distribution of AA metabolites between intra and extracellular compartments indicated that DEN induced de novo synthesis of AA metabolites. The stimulation of AA metabolism by DEN was decreased by H-7 and staurosporine, protein kinase C (PKC) inhibitors, and so could be dependent on PKC activation. The generation of PGs by macrophages after DEN exposure was also inhibited by indomethacin (cyclo-oxygenase inhibitor). DEN at high concentrations (1.6-16 mM) inhibited chemiluminescence production by peritoneal macrophages in a dose-dependent manner, triggered by tumour promoter TPA; lower concentrations (0.8 and 1.2 mM) increased this reactive oxygen intermediates dependent chemiluminescence production induced by TPA. The role of AA metabolism in the alteration of chemiluminescence production by murine peritoneal macrophages treated in vitro with DEN and triggered by TPA has been evaluated by using AA metabolism inhibitors. The stimulation of chemiluminescence by TPA was inhibited by the addition of phospholipase A2 (PLA2) inhibitor, 4-p-BPB; this metabolic inhibitor did not affect the decrease of chemiluminescence production induced by DEN. The cyclo-oxygenase (CO) inhibitor, indomethacin, reversed the inhibition of TPA-induced chemiluminescence caused by DEN. These results suggest that AA and/or a lipoxygenase product can potentiate the reactive oxygen intermediates production by macrophages stimulated by TPA. The CO pathway could be involved in the inhibition by DEN of the reactive oxygen intermediates generating enzyme system. It is suggested that this inhibition could be related to AA metabolites issued from the CO pathway or to DEN oxygenated metabolites issued from the co-oxidation of the DEN by the PGs endoperoxide synthase. These results also raise the problem of macrophage dysfunction by chemical carcinogens and the implication of the CO pathway in this process.
评估了致癌物二乙基亚硝胺（DEN）对小鼠腹腔巨噬细胞前列腺素（PGs）、白三烯（LTs）生成及活性氧中间体产生的影响。体外暴露于DEN（0.8、1.6和8 mM）导致巨噬细胞生成PGs和LTs呈剂量依赖性增加。与仅用12-O-十四酰佛波醇-13-乙酸酯（TPA）刺激的巨噬细胞相比，用DEN处理的腹腔巨噬细胞在用TPA刺激后花生四烯酸（AA）代谢产物的生成增强。对预先标记的巨噬细胞甘油脂质中[3H]AA释放以及AA代谢产物在细胞内和细胞外区室之间分布的研究表明，DEN诱导了AA代谢产物的从头合成。H-7和星形孢菌素（蛋白激酶C（PKC）抑制剂）可降低DEN对AA代谢的刺激作用，因此可能依赖于PKC激活。吲哚美辛（环氧化酶抑制剂）也可抑制DEN暴露后巨噬细胞生成PGs。高浓度（1.6 - 16 mM）的DEN以剂量依赖性方式抑制肿瘤启动子TPA触发的腹腔巨噬细胞化学发光产生；较低浓度（0.8和1.2 mM）则增加TPA诱导的这种依赖活性氧中间体的化学发光产生。通过使用AA代谢抑制剂评估了AA代谢在体外经DEN处理并用TPA触发的小鼠腹腔巨噬细胞化学发光产生改变中的作用。添加磷脂酶A2（PLA2）抑制剂4-p-BPB可抑制TPA对化学发光的刺激；这种代谢抑制剂不影响DEN诱导的化学发光产生的降低。环氧化酶（CO）抑制剂吲哚美辛可逆转DEN对TPA诱导化学发光的抑制作用。这些结果表明AA和/或脂氧合酶产物可增强TPA刺激的巨噬细胞活性氧中间体的产生。CO途径可能参与DEN对活性氧中间体生成酶系统的抑制作用。提示这种抑制可能与CO途径产生的AA代谢产物或PGs内过氧化物合酶对DEN共氧化产生的DEN氧化代谢产物有关。这些结果还提出了化学致癌物导致巨噬细胞功能障碍的问题以及CO途径在此过程中的作用。
