Sodium dichloroacetate improves radiosensitivity of U251 cells / 中国病理生理杂志

AIM:TostudythechangeofradiosensitivityofU251cellsaftertreatedwithsodiumdichloroacetate ( DCA) and further to explore the possible mechanism .METHODS: The U251 cells were divided into 4 groups: control group, DCA group, X-ray irradiation without DCA pretreatment ( IR) group and X-ray irradiation with DCA pretreatment ( DIR) group.MTT assay was applied to determine the cell viability .The intracellular reactive oxygen species ( ROS) were detected by DHE fluorescence .The expression level of Bcl-2 was assessed by Western blot .The percentage of apoptosis of cells was determined by flow cytometry .RESULTS:No difference between control group and DCA group in cell viability (P>0.05) was observed.However, the cell viability of both IR group and DIR group was markedly reduced compared with control group ( P<0.05).Furthermore, the viability of DIR group was significantly decreased compared with IR group ( P<0.05 ) .The percentage of ROS positive cells was obviously increased in DIR group compared with IR group (P<0.05).The expression level of Bcl-2 was sharply decreased in DIR group (P<0.05) and the percentage of apoptosis of cells was significantly elevated ( P<0.05) in DIR group compared with IR group .CONCLUSION:The better antitu-mor effect was obtained by improving the radiosensitivity through pretreating the cells with DCA , and the possible mecha-nism was down-regulation of the Bcl-2 expression by developing the intracellular ROS .

Effect and Mechanism of Reactive Oxygen Species on Apoptosis of Human Hepatocellular Carcinoma Cells Induced by Fenretinide / 胃肠病学

Background:Fenretinide,which is capable of generating reactive oxygen species( ROS ),has emerged as a promising antineoplastic agent based on numerous in vitro and in vivo studies and clinical chemoprevention trials. Preliminary studies showed that fenretinide could induce apoptosis in human hepatocellular carcinoma( HCC)cells in vitro, however,the precise mechanism was not clarified. Aims:To elucidate the effect of ROS on apoptosis of human HCC cells induced by fenretinide and the underlying mechanism. Methods:Human HCC cell line Huh-7 was treated with antioxidant vitamin E,fenretinide or their combination,respectively. ROS in live cells was evaluated by confocal microscopy and flow cytometry;cell viability and apoptosis were assessed by CellTiter-Glo Luminescent Cell Viability Assay Kit and Caspase-Glo3/7 Assay Kit;expression and intracellular localization of nuclear receptor Nur77,as well as expression of stress-induced transcription factor GADD153 were measured by immunofluorescence staining and Western blotting,respectively. Results:Vitamin E pretreatment fully blocked the fenretinide-induced ROS production. In Huh-7 cells pretreated with vitamin E,cell apoptosis induced by fenretinide was significantly reduced(P<0. 05). Furthermore,effect of vitamin E pretreatment was noteworthy on reducing fenretinide-induced GADD153 expression, while no significant impact on fenretinide-induced Nur77 expression and translocation was observed. Conclusions:Elimination of ROS by vitamin E can abrogate the pro-apoptotic effect of fenretinide on Huh-7 cells,which indicates the participation of ROS in fenretinide-induced apoptosis of human HCC cells. Its mechanism might be associated with induction of GADD153 protein expression.