活性氧在4-HPR诱导膀胱癌细胞T24凋亡中的作用

目的研究4-HPR诱导的膀胱癌细胞凋亡，探讨DNA氧化损伤与修复在其中的作用。方法以4-HPR处理T24细胞后，检测其生长抑制情况，用荧光分光光度计检测细胞内活性氧(ROS)含量，用流式细胞仪和琼脂糖凝胶电泳检测细胞凋亡情况，用Western blot法检测DNA修复蛋白XRCC1的表达。结果4-HPR能诱导细胞发生凋亡，2．5、5．0、10．0μmol／L4-HPR引起的凋亡率分别达到1．8％、4．0％和10．5％，在此过程中伴随着细胞内ROS水平升高(最高达到3倍)，并使DNA修复蛋白XRCC1的表达下降，使caspase-3激活。抗氧化物质维生素C能有效地抑制4-HPR引起的ROS升高，并能部分抑制其引起的细胞生长抑制、凋亡及XRCC1蛋白表达的下降。结论ROS的生成并造成DNA损伤可能是4-HPR诱导膀胱癌细胞凋亡的主要机制。

The role of reactive oxygen species in N-[4-hydroxyphenyl] retinamide induced apoptosis in bladder cancer cell lineT24

OBJECTIVE: To study the mechanism of the apoptosis induced by N-4-hydroxyphenyl] retinamide (4-HPR) in bladder cancer cell line T24, and the involvement of DNA damage and repair. METHODS: T24 cells were treated with 4-HPR at the concentration of 2.5, 5.0 and 10.0 micromol/L, and the cell grow inhibition was measured by cell counting assay. The fluorescent intensity of reactive oxygen species (ROS) was determined by spectrofluorometer. The apoptosis was measured by flow cytometry and DNA fragment assay. The expression of XRCC1 protein and activation of caspase-3 were detected by Western blot. RESULTS: 4-HPR induced apoptosis in T24 cell. A dose-dependent increase in the percentage of apoptosis cells was observed (1.8%, 4.0% and 10.5% respectively at 2.5, 5.0, 10.0 micromol/L 4HPR). In the meantime, ROS level in the cell was increased (peaked at 3 fold). It also caused down-regulation of the expression of XRCC1, and activation of caspase-3. Vitamin C effectively inhibited ROS rise induced by 4-HPR, and also partially inhibited cell growth, apoptosis, and down-regulation of the expression of XRCC1. CONCLUSION: The generation of ROS and DNA damage may be the major mechanism of the apoptosis of bladder cancer cell line T24 induced by 4-HPR.