褪黑素对H22肝癌细胞凋亡作用的影响

目的　探讨褪黑素 (MLT)在体外对H2 2肝癌细胞凋亡作用的影响及其机制。方法　应用免疫细胞化学染色方法及原位末端脱氧核苷酸转移酶标记法 (TUNEL)对bcl 2、bax及凋亡细胞进行检测。结果　经MLT孵育相同的时间后 ,凋亡指数 (AI)随MLT浓度的增加而增加 ,中等剂量组与低剂量组及对照组间差异均有显著性 (P <0 .0 5) ,大剂量组、5 Fu组与低剂量组、对照组间差异均有显著性 (P <0 .0 1)。同一药物浓度下 ,中等剂量组、大剂量组及 5 Fu组在孵育 2 4,3 6h后 ,其AI差异有显著性 (P <0 .0 5)。随MLT浓度增加 ,bcl 2的表达呈降低趋势 ,低剂量组与对照组差异有显著性 (P <0 .0 1)。在孵育 2 4,3 6h后 ,bcl 2的下降差异有显著性 (P <0 .0 5)。随MLT浓度增加 ,bax表达在 2 4h内呈上升趋势 ,随时间延长变化不大。结论　MLT在体外有促进肿瘤细胞凋亡的作用 ,且随时间和浓度的增加 ,其促凋亡作用增强 ,bcl 2和bax参与了其中的调节作用

Melatonin in in vitro apoptosis of H22 hepatocarcinoma cells

Objective To study the effect of melatonin (MLT) in in vitro apopt osis of hepatocarcinoma cells and its mechanism. Methods The apoptotic cells, bcl-2 and bax were detected through immunocytochemical method (ICC) and Tolt-m ed iated x-duTP nick end labeling (TUNEL). Computer image analysis system was used t o quantify the expression of bcl-2 and bax by detecting the absorbance value of positive products. Apoptosis index (AI) was used to quantify the number of apop totic cells. Results In vitro, AI increase was both concentration- and time-de pendent through TUNEL. During the same duration, AI of medium dose group was hig her than that of low dose and control group(P<0.05); AI of high dose, medium dose and 5-Fu group were higher than those of low dose and control group( P<0.01),however, there was no significant difference between the low dose an d control group(P>0.05). At the same dose, in high dose, medium dose and 5-F u gro up, the change of AI showed significant difference from 24 to 36 hours(P<0.0 5) . The expression of bcl-2 was down-regulated as the MLT increased, and there w as significant difference between the low dose and control group(P<0.01). But, t he expression of bax was up-regulated as the dose of MLT increased, showing sig n ificant difference between the high dose and control groups(P<0.01). As time w ent on, the expression of bcl-2 was decreased and in every group ,with the chan ge in absorbance value of bcl-2 significantly different from 24 to 36 hours(P <0.0 5), whereas that of bax remained almost unchanged. The ratio of bax/bcl-2 was increased with the increase in the concentration of MLT. Conclusion Melatonin may induce apoptosis in the hepatocarcinoma cells which is concentra tion- and time-dependent,in which bcl-2 and bax are involved.