TNF诱导肿瘤细胞产生氧自由基

Superoxide radicals directly produced from TNFtreated cancer cells

目的：了解氧自由基的产生与ＴＮＦ抗肿瘤活性之间的关系。方法：采用３Ｈ－ＴｄＲ摄入法测定ＴＮＦ对胃癌细胞株Ｘ－１０８、卵巢癌细胞株３ＡＯ和ＡＯ肿瘤细胞的杀伤活性；用细胞色素Ｃ氧化法测定靶细胞经ＴＮＦ刺激后产生的超氧离子水平。结果：ＴＮＦ对Ｘ－１０８、ＡＯ有较明显的杀伤活性，３Ｈ－ＴｄＲ摄入量的降低与ＴＮＦ浓度的增加一致，而３ＡＯ则对ＴＮＦ呈明显的抵抗。Ｘ－１０８细胞株在经ＴＮＦ处理８ｈ后即可检测出超氧离子，并且在２４ｈ后达到高峰。Ｘ－１０８和ＡＯ细胞内超氧离子的水平与ＴＮＦ的剂量有关。对于抵抗ＴＮＦ的３ＡＯ卵巢癌细胞株，其超氧离子的水平与对照组无明显差别。阿霉素能够增强ＴＮＦ诱导氧自由基的能力。结论：ＴＮＦ的受体后效应——自由基的产生可能是ＴＮＦ杀伤靶细胞的重要机制之一。

Objective: To find out the relationship between the TNF induced superoxide anion generation and its cytotoxicity. Methods: Tritiated thymidine uptake assay was used to determine the cytotoxicity of TNF to X108, 3AO and AO cancer cells. Released superoxide anion from rhTNFtreated tumor cells was determined in triplicate reaction mixtures. Results: It showed that rhTNF had significant cytotoxic effect on X108 and AO cancer cells, as shown by the reduction of 3HTdR incorporation in a dosedependent manner. Ovarian cancer cell line 3AO seemed to be resistant to rhTNF treatment. The superoxide anion could be produced from X108 and AO cell lines after exposure to rhTNF for 8 h but not from 3AO cell line. The amount of superoxide anion produced was also dosedependent, and increased as the exposure time extended up to 24 h in TNFsensitive cancer cells. In TNFresistant ovarian cancer cells 3AO, the amount of superoxide anion was the same as the control group when treated with 1×107 U/L of rhTNF. The superoxide anion in X108 cancer cells was found to be significantly elevated when TNF cooperated with adriamycin. Conclusion: These findings suggest that free radical genesis, as postreceptor reaction of TNF, may be one of the main mechanisms of TNF induced cytotoxic effects on target cells.