Protein kinase C-E: regulates the apoptosis and survival of glioma cells
Protein kinase C-E: regulates the apoptosis and survival of glioma cells
复制标题
DOI：
10.1158/0008-5472.can-05-1064
复制
发表时间：
2005-08-15
期刊：
影响因子：
11.2
通讯作者：
Brodie, C
中科院分区：
文献类型：
--
作者：
Okhrimenko, H;Lu, W;Brodie, C
在这项研究中，我们利用肿瘤坏死因子相关凋亡诱导配体 (TRAIL) 刺激细胞并沉默 PKC epsilon 表达，研究了蛋白激酶 C (PKC)-epsilon 在神经胶质瘤细胞凋亡和存活中的作用。用 TRAIL 治疗神经胶质瘤细胞可在治疗后 3 至 5 小时内诱导激活、半胱天冬酶依赖性裂解和 PKC epsilon 下调。 PKC epsilon 的过度表达抑制 TRAIL 诱导的细胞凋亡，作用于 caspase 8 下游以及 Bid 裂解和线粒体细胞色素 c 释放的上游。半胱天冬酶抗性 PKC epsilon 突变体 (D383A) 比 PKC epsilon 更具保护性，表明 PKC epsilon 的裂解及其下调均有助于 TRAIL 的凋亡作用。为了进一步研究 PKC epsilon 在神经胶质瘤细胞凋亡中的作用，我们使用针对 PKC epsilon mRNA 的短干扰 RNA，发现 PKC epsilon 表达沉默可诱导各种神经胶质瘤细胞系和原代神经胶质瘤培养物的凋亡。为了描述沉默 PKC epsilon 诱导的细胞凋亡的分子机制，我们检测了各种细胞凋亡相关蛋白的表达和磷酸化。我们发现敲低 PKC epsilon 不会影响 Bcl2 和 Bax 的表达，也不影响 Erk1/2、c-Jun-NH2-kinase、p38 或 STAT 的磷酸化和表达，而选择性降低 AKT 的表达。同样，TRAIL 降低了神经胶质瘤细胞中 AKT 的表达，并且这种降低在过表达 PKC epsilon 的细胞中被消除。我们的结果表明，PKC epsilon 的裂解及其下调在 TRAIL 的细胞凋亡效应中发挥重要作用。此外，PKC epsilon 调节 AKT 表达，对于神经胶质瘤细胞的存活至关重要。
In this study, we examined the role of protein kinase C (PKC)-epsilon in the apoptosis and survival of glioma cells using tumor necrosis factor-related apoptosis inducing ligand (TRAIL)-stimulated cells and silencing of PKC epsilon expression. Treatment of glioma cells with TRAIL induced activation, caspase-dependent cleavage, and down-regulation of PKC epsilon within 3 to 5 hours of treatment. Overexpression of PKC epsilon inhibited the apoptosis induced by TRAIL, acting downstream of caspase 8 and upstream of Bid cleavage and cytochrome c release from the mitochondria. A caspase-resistant PKC epsilon mutant (D383A) was more protective than PKC epsilon, suggesting that both the cleavage of PKC epsilon and its down-regulation contributed to the apoptotic effect of TRAIL. To further study the role of PKC epsilon in glioma cell apoptosis, we employed short interfering RNAs directed against the mRNA of PKC epsilon and found that silencing of PKC epsilon expression induced apoptosis of various glioma cell lines and primary glioma cultures. To delineate the molecular mechanisms involved in the apoptosis induced by silencing of PKC epsilon, we examined the expression and phosphorylation of various apoptosis-related proteins. We found that knockdown of PKC epsilon did not affect the expression of BcI2 and Bax or the phosphorylation and expression of Erk1/2, c-Jun-NH2-kinase, p38, or STAT, whereas it selectively reduced the expression of AKT. Similarly, TRAIL reduced the expression of AKT in glioma cells and this decrease was abolished in cells over-expressing PKC epsilon. Our results suggest that the cleavage of PKC epsilon and its down-regulation play important roles in the apoptotic effect of TRAIL. Moreover, PKC epsilon regulates AKT expression and is essential for the survival of glioma cells.