Elevated Akt activity protects the prostate cancer cell line LNCaP from TRAIL-induced apoptosis
Elevated Akt activity protects the prostate cancer cell line LNCaP from TRAIL-induced apoptosis
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DOI：
10.1074/jbc.m005196200
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发表时间：
2001-04-06
影响因子：
4.8
通讯作者：
Kraft, AS
中科院分区：
文献类型：
--
作者：
Nesterov, A;Lu, XJ;Kraft, AS
我们发现前列腺癌细胞系阿尔瓦-31、PC-3和DU 145对TRAIL诱导的凋亡高度敏感（（t）在bar下肿瘤坏死因子-（r）在bar下相关（a）在bar三元共聚物下相关（i）在bar下诱导（l）在bar配体下相关），而细胞系TSU-Prl和JCA-1是中等敏感的，而LNCaP细胞系是抗性的。LNCaP细胞缺乏活性脂质磷酸酶PTEN（磷脂酰肌醇（PI）3-激酶/Akt途径的负调节剂），并表现出高组成性Akt活性。使用渥曼青霉素和LY-294002抑制PI 3-激酶抑制了组成型Akt活性并使LNCaP细胞对TRAIL敏感。单独用TRAIL处理LNCaP细胞诱导半胱天冬酶8和XIAP蛋白的切割。然而，BID的加工、细胞色素c的线粒体释放、半胱天冬酶7和9的活化以及细胞凋亡不发生，除非TRAIL与渥曼青霉素、LY-294002或放线菌酮组合。通过Bcl-2过表达阻断细胞色素c释放使得LNCaP细胞对TRAIL加渥曼青霉素处理具有抗性，但不影响半胱天冬酶8或BID加工。这表明在这些细胞中，线粒体是增殖所需的，而不是凋亡级联的起始。用表达组成型活性Akt的腺病毒感染LNCaP细胞逆转了渥曼青霉素增强TRAIL诱导的BID切割的能力。因此，在LNCaP细胞中TRAIL诱导的细胞凋亡的PI 5激酶依赖性阻断似乎是由Akt通过抑制BID切割介导的。
We find that the prostate cancer cell lines ALVA-31, PC-3, and DU 145 are highly sensitive to apoptosis induced by TRAIL ((t) under bar umor-necrosis factor-(r) under bar elated (a) under bar poptosis-(i) under bar nducing (l) under bar igand), while the cell lines TSU-Prl and JCA-1 are moderately sensitive, and the LNCaP cell line is resistant. LNCaP cells lack active lipid phosphatase PTEN, a negative regulator of the phosphatidylinositol (PI) 3-kinase/Akt pathway, and demonstrate a high constitutive Akt activity. Inhibition of PI 3-kinase using wortmannin and LY-294002 suppressed constitutive Akt activity and sensitized LNCaP cells to TRAIL, Treatment of LNCaP cells with TRAIL alone induced cleavage of the caspase 8 and XIAP proteins. However, processing of BID, mitochondrial release of cytochrome c, activation of caspases 7 and 9, and apoptosis did not occur unless TRAIL was combined with either wortmannin, LY-294002, or cycloheximide, Blocking cytochrome c release by Bcl-2 overexpression rendered LNCaP cells resistant to TRAIL plus wortmannin treatment but did not affect caspase 8 or BID processing. This indicates that in these cells mitochondria are required for the propagation rather than the initiation of the apoptotic cascade, Infection of LNCaP cells with an adenovirus expressing a constitutively active Akt reversed the ability of wortmannin to potentiate TRAIL-induced BID cleavage. Thus, the PI 5-kinase-dependent blockage of TRAIL-induced apoptosis in LNCaP cells appears to be mediated by Akt through the inhibition of BID cleavage.