Enterococcus faecalis produces extracellular superoxide and hydrogen peroxide that damages colonic epithelial cell DNA
Enterococcus faecalis produces extracellular superoxide and hydrogen peroxide that damages colonic epithelial cell DNA
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DOI：
10.1093/carcin/23.3.529
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发表时间：
2002-03-01
期刊：
影响因子：
4.7
通讯作者：
Moore, DR
中科院分区：
文献类型：
--
作者：
Huycke, MM;Abrams, V;Moore, DR
粪肠球菌（Enterococcus faecalis）是人体肠道中的一种微生物，通过膜结合的去甲基甲萘醌（demethylmenaquinone）的自氧化作用，产生大量的胞外超氧化物（O-2（-））和衍生的活性氧物质，如H2 O2和羟基自由基。由于这些氧化剂可能是与散发性腺瘤性息肉和结直肠癌相关的染色体不稳定性（CIN）的重要原因，因此E。采用碱裂解单细胞凝胶电泳（comet）法检测粪肠球菌对真核细胞DNA的损伤作用。中国仓鼠卵巢细胞和HT-29肠上皮细胞在与野生型E. faecalis菌株OG 1 RF，但不是具有减弱的胞外O-2（-）产生的转座子失活突变体。E.过氧化氢酶可阻止粪便介导的DNA损伤，但锰超氧化物歧化酶不能阻止，表明来自O-2（-）的H2 O2是遗传毒素。在大鼠肠道定植模型中，OG 1 RF导致粪便中H2 O2和5，5-二甲基-1-吡咯啉N-氧化物的羟基和巯基加合物的浓度显着较高，通过电子自旋共振-自旋捕集，与具有衰减O-2（-）生产的突变株定植的大鼠相比。用彗星试验，从大鼠结肠腔细胞与O-2（-）-产生的E。与用突变体定殖的对照大鼠相比，粪肠球菌显示出显著增加的DNA损伤。这些发现表明，一个潜在的深远的作用，胞外自由基的生产由E。粪球菌促进与散发性腺瘤性息肉和结直肠癌相关的CIN。
Enterococcus faecalis is a commensal microorganism of the human intestinal tract that produces substantial extracellular superoxide (O-2(-)), and derivative reactive oxygen species such as H2O2 and hydroxyl radical, through autoxidation of membrane-associated demethylmenaquinone. Because these oxidants may be important as a cause of chromosomal instability (CIN) associated with sporadic adenomatous polyps and colorectal cancer, the ability of E. faecalis to damage eukaryotic cell DNA was examined using the alkaline lysis single cell gel electrophoresis (comet) assay. Both Chinese hamster ovary and HT-29 intestinal epithelial cells showed increased DNA damage after co-incubation with wild-type E. faecalis strain OG1RF, but not a transposon-inactivated mutant with attenuated extracellular O-2(-) production. E. faecalis-mediated DNA damage was prevented by catalase, but not manganese superoxide dismutase, indicating H2O2 arising from O-2(-) was the genotoxin. In a rat model of intestinal colonization, OG1RF resulted in significantly higher stool concentrations of H2O2 and 5,5-dimethyl-1-pyrroline N-oxide adducts of hydroxyl and thiyl radicals, as identified by electron spin resonance-spin trapping, compared with rats colonized with a mutant strain having attenuated O-2(-) production. Using the comet assay, luminal cells from the colon of rats colonized with O-2(-)-producing E. faecalis showed significantly increased DNA damage compared with control rats colonized with the mutant. These findings suggest a potentially profound role for extracellular free radical production by E. faecalis in promoting CIN associated with sporadic adenomatous polyps and colorectal cancer.