鞘氨醇激酶2与蛋白激酶D参与调控丁酸钠诱导的人肝癌细胞凋亡

Protein kinase D and sphingosine kinase 2 are involved in sodium butyrate-induced apoptosis in human liver cancer HepG2 cells

目的探讨蛋白激酶D(PKD)与鞘氨醇激酶2(SphK2)参与调控丁酸钠诱导的人肝癌HepG2细胞凋亡的分子机制。方法采用流式细胞仪检测不同浓度丁酸钠作用48 h后人肝癌HepG2细胞的凋亡率,以及干扰或过表达PKD或SphK2对丁酸钠诱导人肝癌HepG2细胞凋亡率的影响;并且在分别干扰PKD或SphK2后以免疫印迹法检测其对丁酸钠诱导另一蛋白激活(磷酸化)的影响。结果丁酸钠能明显诱导HepG2细胞凋亡(P<0.01),且具有浓度依赖性;而在PKD或SphK2被干扰后,丁酸钠诱导细胞凋亡率比未干扰细胞明显增高(P<0.01),而过表达PKD或SphK2的细胞在丁酸钠作用下其凋亡率比空质粒对照组细胞明显下降(P<0.01),并且干扰PKD可阻断丁酸钠诱导的SphK2激活(P<0.01),而干扰SphK2则对PKD的激活无影响(P<0.01)。结论 PKD和SphK2均可负性调控丁酸钠诱导的HepG2细胞凋亡。

Objective To explore the roles of protein kinase D （PKD） and sphingosine kinase 2 （SphK2） in sodium butyrate-induced apoptosis of human liver cancer HepG2 cells. Method Using flow cytometry, the percentage of apoptotic HepG2 cells was examined after treatment with sodium butyrate of different concentrations. The effects of down-regulation and over-expression of SphK2 or PKD on sodium butyrate-induced apoptosis were analyzed. With Western blotting, the changes in the activated （phosphorylated） forms of Results SphK2 or PKD induced by sodium butyrate with or without interference of the other enzyme were detected Sodium butyrate induced apoptosis of HepG2 ceils significantly （P 〈 0. 01 ） in a concentration- dependent manner. After the down-regulation of PKD or SphK2, the sodium butyrate-induced apoptosis was obviously potentiated, as compared to the non-interfered control cells （P 〈0. 01 ）. On the contrary, the apoptosis of the cells with PKD or SphK2 overexpressed was significantly prohibited, in comparison with the vehicle plasmid-transfected cells （P 〈0. 01 ）. Moreover, the interference of SphK2 did not affect activation of PKD by sodium butyrate （P 〈 0. 01 ）, while PKD down-regulation resulted in the absence of SphK2 activation （ P 〈 0. 01 ）. Conclusion Both SphK2 and PKD negatively regulate apoptosis of HepG2 cells induced by sodium butyrate.