| 摘要: | 三氯乙烯與四氯乙烯由於具有特殊的物化特性，因此廣泛應用工業界作為金屬脫脂溶劑，或乾洗店用作去漬劑。然而意外的滲漏或不當的棄置常使此類化合物污染土壤及地下水，並由於自然分解不易而致長期存在於環境中。本實驗利用氣相暴露法，以細胞群落形成分析(colony formation)、微核(micronuclei)分析以及MTT細胞活性測定等方法探討三氯乙烯及四氯乙烯對細胞之毒性。將直徑為60 mm 的培養皿中央，貼上直徑為25 mm之玻璃培養皿，然後將三氯乙烯(20-80μl)或四氯乙烯(5-20μl)加入中央玻璃培養皿，使三氯乙烯或四氯乙烯揮發並溶解於周圍含細胞的培養液。本實驗以5μl、10μl或20μl的四氯乙烯暴露24小時後，細胞生長抑制情況與暴露於20μl、40μl或80μl三氯乙烯相當，此結果顯示四氯乙烯對三株人類肺癌細胞之毒性為三氯乙烯的四倍。H1299細胞內glutathione (GSH)含量高於H322及H460，對三氯乙烯與四氯乙烯耐受性皆大於其他兩株細胞，然而，以200μM DL-buthionine-[S,R]-sulfoximine (BSO，GSH合成抑制劑)降低細胞內GSH含量後，H1299對四氯乙烯的耐受性明顯下降。另外，三氯乙烯或四氯乙烯可誘導H460細胞glutathione S-transferase (GST)酵素活性。因此推論GSH直接或間接參與細胞代謝四氯乙烯，而且扮演輔助排毒功能。在遺傳毒性方面，三氯乙烯及四氯乙烯並未誘發H1299細胞產生微核，因此三氯乙烯或四氯乙烯對人類肺癌細胞的遺傳毒性，仍然有待進一步研究證實。 Trichloroethylene (TCE) and tetrachloroethylene (perchloroethylene, PCE) are widespreadly used in industry as degreasing agent or used in dry-clean. However, accident spill and unsuitable disposal often result in the pollution of soil and groundwater by TCE and PCE. These two chlorinated compounds may exist in the environment for a long time due to the low degradation rate. This thesis was aimed to investigate the toxicity of TCE or PCE to three human lung cancer cell lines, H322, H460 and H1299, in colony formation, micronuclei (MN) assay and MTT assay by employing an in vitro vaporour exposure system. The cells were cultured in a 60-mm petri dish with a 25-mm glass dish glued in the central area. The TCE (20-80μl) or PCE (5-20μl) was added in the central glass dish so as to evaporate and dissolved in the surrounding medium in which cells were growing. The results show that PCE was 4-fold more toxic to all three lung cells than TCE, since treatment of cells with 5, 10 or 20 μl PCE for 24 hr resulted in the same degree of inhibition to cell growth when compared , respectively, to 20 μl, 40 μl, 80 μl of TCE treatment. The H1299 cells was shown higher levels of glutathione (GSH) than H322 and H460 cells, and H1299 was more resistant to TCE or PCE than H322 and H460 cells. However the tolerance of H1299 to PCE decreased greatly after pretreatment with 200 μM DL-buthionine-[S,R]-sulfoximine (BSO, a GSH depleting agent. Furthermore TCE or PCE-treatment resulted in the elevation of glutathione S-transferase (GST) activity. Therefore, it could be draw an inference that GSH and GST play a role in the metabolism of PCE. In addition, TCE or PCE-treatment in H1299 had no effect on the formation MN. The genotoxicity of TCE or PCE remains for further investigation. |
