目的:探讨光敏化促进姜黄素诱导人胃癌MGC-803细胞凋亡及其机制.方法:用MTT法检测光敏化姜黄素对胃癌MGC-803细胞株的增殖抑制率,Hoechst 33258荧光染色观察细胞核形态的变化,流式细胞术检测细胞的凋亡率、线粒体膜电位、细胞内活性氧和Ca2+;比色法检测caspase-3、8和9酶活性;Western blotting分析细胞色素C、Bcl-2、Bax和热休克蛋白70(HSP70)水平.结果:单纯姜黄素(5.0μmol/L)对MGC-803细胞增殖抑制率为(29.74±2.30)%,在光学显微镜下可见部分凋亡细胞,凋亡率为(12.54±1.75)%.而光敏化姜黄素组细胞增殖抑制率则为(44.93±3.61)%,在光学显微镜下能见明显细胞核形态改变,染色质凝集,凋亡小体形成,凋亡率为(26.58±2.67)%,细胞周期主要阻滞于G0/G1期.光敏化姜黄素显著降低线粒体膜电位,显著增加细胞色素C、细胞内活性氧和Ca2+以及caspase-3、8和9酶活性,与单纯姜黄素组比较,差异显著(P＜0.01).Western blotting结果显示光敏化姜黄素同时显著抑制Bcl-2和HSP70蛋白表达水平.结论:光敏化姜黄素通过Bcl-2和线粒体途径增强其诱导胃癌MGC-803细胞凋亡的作用.%AIM: To investigate the effect of photoactivated curcumin on apoptosis of human gastric cancer MGC — 803 cells. METHODS: The effect of photoactivated curcumin on the growth inhibitory rate of gastric cancer MGC - 803 cells was detected by MTT assay. The changes of nuclear morphology were observed under optical microscope with Hoechst 33258 fluorescent staining. The apoptotic rate, mitochondrial membrane potential, intracellular reactive oxygen species and Ca2 + level was determined by flow cytometry. The activity of caspase - 3 , caspase - 8 and caspase - 9 was detected by colorimetry. The protein levels of cytochrome C, Bcl - 2, Bax and heat - shock protein 70 ( HSP70 ) were analyzed by Western blotting. RESULTS: The growth inhibitory rate of MGC - 803 cells treated with curcumin at concentration of 5. 0 μmol/L was ( 29.74 ± 2. 30 )% . Some apoptotic cells were observed under optical microscope, and the apoptotic rate was ( 12. 54 ± 1. 75 )%. The growth inhibitory rate of MGC — 803 cells treated with photoactivated curcumin was ( 44. 93 ±3. 61 )%. Significant morphological changes in the nucleus, such as chromatin condensation and apoptotic body formation, were observed under light microscope, and the apoptotic rate was ( 26. 58 ±2. 67 )% . The cell cycle was arrested at G0/G1 phase. Compared with curcumin group, significant reduction in mitochondrial membrane potential,significant increase in cytochrome C, intracellular reactive oxygen species, Ca2 + level and the activity of caspase — 3, caspase — 8 and caspase —9 were observed in photoactivated curcumin group ( P <0. 01 ). Photoactivated curcumin also significantly inhibited the protein expression of Bcl -2 and HSP70 in the cells. CONCLUSION: Photoactivated curcumin enhances the apoptosis of gastric cancer MGC - 803 cells by inhibiting Bcl - 2 expression and promoting the mitochondrial pathway.
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