神经酰胺在儿茶素诱导LoVo细胞凋亡中的作用

 目的 探讨神经酰胺在表没食子儿茶素没食子酸酯(EGCG)、表没食子儿茶素(EGC)和表儿茶素(EC)诱导大肠癌LoVo细胞凋亡及其差异性中的作用。方法 EGCG，EGC和EC以及C_2-和C_6-神经酰胺处理LoVo细胞后，用琼脂糖凝胶电泳，Heochst染色、流式细胞术定性和定量检测LoVo细胞凋亡相关的形态学和生化方面的改变；用二酰基甘油激酶法测定3种儿茶素处理LoVo细胞后其神经酰胺含量的变化。结果 EGCG和EGC处理LoVo细胞后，可引起LoVo细胞的凋亡，C_2-和C_6-神经酰胺也可引起相似的改变，但EC则无此作用。EGCG或EGC处理LoVo细胞后细胞内神经酰胺含量先一短暂的升高后逐渐回到基线水平，而EC则先引起短暂的下降再逐渐回升至基线水平。结论 3种儿茶素在诱导LoVo细胞凋亡时呈现出差异性，这种差异性与它们引起LoVo细胞内神经酰胺含量变化的差异性有关。

Effectsof ceramide on individual catechins-induced apoptosis and their differences in colon LoVocells

OBJECTIVE To investigate the effects of ceramide on apoptosis and its difference in colon carcinoma LoVo cells which were induced by the major catechins in green tea,including (-)epigallocatechin3gallate (EGCG),(-)epigallocatechin (EGC),and (-)epicatechin (EC).METHODS After treatment of LoVo cells with EGCG,EGC and EC,as well as C 2 and C 6ceramide,the apoptosisassociated alterations in morphology and biochemistry were examined qualitatively and quantitatively usig agarose gel electrophoresis,staining with the DNAbinding fluorochrome bisbenzimide,Hoechst 33342,and flow cytometry (FCM).The changes of intracellular ceramide content after treatment of LoVo cells with EGCG,EGC,or EC were determined by diacylglycerol kinase assay.RESULTS Treatment of LoVo cells with EGCG or EGC resulted in the apoptosisassociated alterations such as the formation of internucleosomal DNA fragements on agarose gel electrophoresis and hypodiploid peaks on the histogram of FCM.EC,however,did not have the effects,indicating that there were different effects of the three individual catechins on the induction of apoptosis in LoVo cells.In addition,the addition of membranepermeable C 2and C 6ceramide to LoVo cells mimicked EGCG or EGC in leading to the apoptotic alterations.Treatment of LoVo cells with EGCG or EGC resulted in a transient increase in ceramide content at about 20 min,which was 2 to 3 times higher than that in the control cells,and then back gradually to base line level.In contrast,EC,resulted in a first decrease within 30 min and then a gradual increase to base line level.CONCLUSION Ceramide takes part in the regulation of the catechinsinduced apoptosis in LoVo cells.The differences in the effects of the individual catechins on the induction of apoptosis in LoVo cells may be associated with the differences in the generation of intracellular ceramide.