己酮可可碱对嘧啶拮抗物细胞毒性的影响

Cytotoxic Influence of Pentoxifylline on Pyrimidine Antagonist

目的:观察己酮可可碱(pentoxifylline,PTX)在体外对嘧啶拮抗物(E)-(2')-脱氧-氟亚甲基胞苷犤(E)-2'-deoxy-2'-(fluoromethylene)cytidine,FMdC犦和5-氟尿嘧啶(5-fluorouracil,5-FU)细胞毒性的影响。方法:用MTT法检测PTX和FMdC或5-FU对人结肠癌细胞系WiDr的细胞毒性。用流式细胞仪检测FMdC和PTX的细胞周期效应。结果:0.25-2.0mmol/LPTX增加FMdC和5-FU的细胞毒性。2mmol/LPTX能使FMdC的半数抑制浓度(IC50)从80nmol/L降到24nmol/L;对5-FU的IC50从10μmol/L降到1.1μmol/L。Isoborogram分析表明,PTX和FMdC或5-FU的细胞毒性作用为相乘作用。在WiDr细胞,20-40nmol/LFMdC引起S期阻滞,并与浓度相关。20nmol/LFMdC时,S期阻滞仅在48h能观察到;30nmol/L和40nmol/LFMdC时,12h开始出现S期阻滞,24h达高峰,48h仍可见明显阻滞。0.5-2.0mmol/LPTX和30nmol/LFMdC共同处理细胞24h,PTX能去除FMdC引起的S期阻滞。0.5mmol/L和1.0mmol/LPTX将S期比例从64.6%分别减少到54.4%和39.3%。结论:PTX能增强体外FMdC和5-FU的细胞毒性,通过PTX去除S期阻滞,为提高嘧啶拮抗物的细胞毒性提供了一种有效途径。

Objective: The aim of this study was to investigate the effect of pentoxifylline on nucleoside analogues (E) 2′ deoxy 2′ (fluoromethylene) cytidine and 5 fluorouracil induced cytotoxicity. Methods: MTT assay was used to evaluate the cytotoxicity of pentoxifylline and (E) 2′ deoxy 2′ (fluoromethylene) cytidine or 5 fluorouracil in a human colorectal cancer cell line WiDr. Cell cycle distribution induced by (E) 2′ deoxy 2′ (fluoromethylene) cytidine and pentoxifylline was analyzed by flow cytometry. Results: Pentoxifylline at 0.25-2.0 mmol/L enhanced the cytotoxicity of (E) 2′ deoxy 2′ (fluoromethylene) cytidine and 5 fluorouracil. 2 mmol/L pentoxifylline lowered the 50% inhibition concentration (IC50) of (E) 2′ deoxy 2′ (fluoromethylene) cytidine from 80 nmol/L to 24 nmol/L, and IC50 of 5 fluorouracil from 10 μmol/L to 1.1 μmol/L, respectively. Isobologram analysis showed that the cytotoxic effect of pentoxifylline and (E) 2′ deoxy 2′ (fluoromethylene) cytidine or 5 fluorouracil was supra additive. Exposure of WiDr cells to 20-40 nmol/L (E) 2′ deoxy 2′ (fluoromethylene) cytidine alone resulted an S phase arrest in a dose dependent manner. At 20 nmol/L (E) 2′ deoxy 2′ (fluoromethylene) cytidine, significant S phase arrest was observed only at 48 h after treatment. S phase arrest induced by 30 nmol/L and 40 nmol/L of (E) 2′ deoxy 2′ (fluoromethylene) cytidine appeared at 12 h, peaks at 24 h, and reached a plateau at 48 h. Treatment with 30 nmol/L of (E) 2′ deoxy 2′ (fluoromethylene) cytidine in addition of 0.5-2.0 mmol/L pentoxifylline for 24 h abrogated (E) 2′ deoxy 2′ (fluoromethylene) cytidine induced S phase arrest. Pentoxifylline at concentrations of 0.5 mmol/L and 1.0 mmol/L reduced S phase arrest from 64.6% to 54.4% and to 39.3%. Conclusions: Pentoxifylline is able to potentiate the cytotoxicity of (E) 2′ deoxy 2′ (fluoromethylene) cytidine and 5 fluorouracil. The abrogation of S phase arrest by pentoxifylline may provide an effective strategy for enhancing the cytotoxicity of nucleoside analogues.