己酮可可碱对人肝癌细胞株Hep3b的放射增敏作用

Cytotoxicity of pentoxifylline and its effect on human hepatoma cell line Hep3b radiosensitivity

目的观察己酮可可碱(PTX)对人肝癌细胞株Hep3b的放射增敏作用。方法以Hep3b人肝癌细胞株为研究对象,应用MTT法检测PTX的药物毒性;应用克隆形成实验(colony forming assay)观察PTX对Hep3b细胞株的放射敏感性的影响;流式细胞仪(FCM)技术测定照射后Hep3b细胞株细胞周期的再分布并观察PTX能否去除放射引起的细胞周期阻滞。结果不同浓度的PTX作用于人肝癌Hep3b细胞株48 h后,其细胞毒性呈剂量依赖性,最适浓度为2 mmol/L。PTX能明显降低放射后Hep3b细胞的克隆形成率,其放射增敏比为2.68±0.24(P>0.05)。FCM实验结果显示,照射明显导致Hep3b细胞株G2期阻滞,Hep3b细胞在照射后20 h G2/M期比例分别为86.8%和14.8%(P<0.05),PTX能够去除放射引起的Hep3b细胞G2期阻滞。结论PTX对Hep3b细胞株有放射增敏作用,其作用机制可能与PTX去除放射引起的G2期阻滞有关。

Objective To investigate the effects ofpentoxifylline （PTX） on radiation induced-cell cycle redistribution and radiasensitivity of human hepatocellular carcinoma cell line Hep3b. Methods MTT assay was performed to evaluate the cytotoxicity of PTX on p53-defective human hepatoceUular carcinoma cell line Hep3b and clonogenic assay employed to observe its effects on the radiosensitivity of the cells quantified by calculating the sensitive enhancement ratio （SER）. Flow cytometry was performed to observe the cell cycle changes of Hep3b cells in response to X-ray irradiation and the interventional effect of PTX. Results The cytotoxicity of PTX on the cells increased in a dose-dependent manner following a 48-hour treatment, with the optimal dose range of 1-5 mmol/L. A sub-toxic dose of PTX at 2 mmol/L was then used in subsequent experiments. Clonogenic survival assays up to 12 Gy demonstrated that p53-defective Hep3b cells （SER of 2.68±0.24） were sensitized by PTX （2 mmol/L）. PTX （2 mmol/L） treatment following exposure to irradiation （6 Gy） resulted in abrogation of radiation-induced G2/M arrest of Hep3b cells, and the proportions of Hep3b cells in G2/M phase were 86.8% and 14.8% after exposure to 6 Gy alone and 6 Gy plus 2 mmol/L PTX, respectively. Conclusion Radiosensitization by PTX is possibly associated with the abrogation of G2/M arrest in Hep3b cells following radiation exposure, suggesting that potential clinical application of PTX may enhance the efficacy of radiotherapy against hepatoceUular carcinoma.