Analysis of in vivo and in vitro DNA strand breaks from trihalomethane exposure.
Analysis of in vivo and in vitro DNA strand breaks from trihalomethane exposure.
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DOI：
10.1186/1477-3163-3-2
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发表时间：
2004-02-17
影响因子：
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通讯作者：
DeAngelo, Anthony B
中科院分区：
文献类型：
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作者：
Geter, David R;Chang, Lina W;DeAngelo, Anthony B
背景技术背景：流行病学研究表明，饮用氯化的地表沃茨会增加两大人类死亡原因-结肠直肠癌和膀胱癌-的风险。三卤甲烷（THMs）是使用氯消毒饮用水时形成的副产品。本研究的目的是检测三卤甲烷（TCM）、溴二氯甲烷（BDCM）、二溴氯甲烷（DBCM）和三溴甲烷（TBM）在（1）CCRF-CEM人淋巴细胞白血病细胞、（2）体外暴露的原代大鼠肝细胞（PRH）和（3）灌胃或饮水暴露的大鼠中诱导DNA链断裂（SB）的能力。方法：DNA碱性解旋法（DAUA）测定DNA SB。将CCRF-CEM细胞暴露于单独的THMs 2小时。立即分析一半细胞的DNA SB，并将一半细胞转移到新鲜培养基中并在测试DNA SB之前再孵育22小时。将PRH暴露于单独的THMs 4小时，然后分析DNA SB。将F344/N大鼠暴露于单独的THMs 4小时，2周，结果：CCRF-CEM细胞经5或10 mM溴化THMs作用2 h后，产生DNA SB，其活性顺序为TBM>DBCM>BDCM，TCM无活性。在22小时恢复期后，除10 mM DBCM和1 mM TBM外，所有组的SB均较少。发现CCRF-CEM细胞对GSTT 1 -1基因呈阳性，但未检测到活性。在暴露于单独THMs的PRH或F344/N大鼠中未观察到与细胞毒性无关的DNA SB。结论：与对照细胞相比，暴露于5或10 mM溴化THMs 2小时的CCRF-CEM细胞显示DNA SB显著增加。此外，暴露于DBCM和TBM的CCRF-CEM细胞似乎具有受损的DNA修复能力，如暴露后22小时DNA SB量增加所证明的。发现CCRF-CEM细胞对GSTT 1 -1基因呈阳性，但未检测到活性。在暴露于单独THMs的PRH或F344/N大鼠中未观察到DNA SB。
BACKGROUND: Epidemiological studies have linked the consumption of chlorinated surface waters to an increased risk of two major causes of human mortality, colorectal and bladder cancer. Trihalomethanes (THMs) are by-products formed when chlorine is used to disinfect drinking water. The purpose of this study was to examine the ability of the THMs, trichloromethane (TCM), bromodichloromethane (BDCM), dibromochloromethane (DBCM), and tribromomethane (TBM), to induce DNA strand breaks (SB) in (1) CCRF-CEM human lymphoblastic leukemia cells, (2) primary rat hepatocytes (PRH) exposed in vitro, and (3) rats exposed by gavage or drinking water. METHODS: DNA SB were measured by the DNA alkaline unwinding assay (DAUA). CCRF-CEM cells were exposed to individual THMs for 2 hr. Half of the cells were immediately analyzed for DNA SB and half were transferred into fresh culture medium and incubated for an additional 22 hr before testing for DNA SB. PRH were exposed to individual THMs for 4 hr then assayed for DNA SB. F344/N rats were exposed to individual THMs for 4 hr, 2 weeks, and to BDCM for 5 wk then tested for DNA SB. RESULTS: CCRF-CEM cells exposed to 5- or 10-mM brominated THMs for 2 hr produced DNA SB. The order of activity was TBM>DBCM>BDCM; TCM was inactive. Following a 22-hr recovery period, all groups had fewer SB except 10-mM DBCM and 1-mM TBM. CCRF-CEM cells were found to be positive for the GSTT1-1 gene, however no activity was detected. No DNA SB, unassociated with cytotoxicity, were observed in PRH or F344/N rats exposed to individual THMs. CONCLUSION: CCRF-CEM cells exposed to the brominated THMs at 5 or 10 mM for 2 hr showed a significant increase in DNA SB when compared to control cells. Additionally, CCRF-CEM cells exposed to DBCM and TBM appeared to have compromised DNA repair capacity as demonstrated by an increased amount of DNA SB at 22 hr following exposure. CCRF-CEM cells were found to be positive for the GSTT1-1 gene, however no activity was detected. No DNA SB were observed in PRH or F344/N rats exposed to individual THMs.