Apoptosis induction in human melanoma cells by inhibition of MEK is caspase-independent and mediated by the Bcl-2 family members PUMA, Bim, and Mcl-1
Apoptosis induction in human melanoma cells by inhibition of MEK is caspase-independent and mediated by the Bcl-2 family members PUMA, Bim, and Mcl-1
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DOI：
10.1158/1078-0432.ccr-07-0665
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发表时间：
2007-08-15
影响因子：
11.5
通讯作者：
Hersey, Peter
中科院分区：
文献类型：
--
作者：
Wang, Yu Fang;Jiang, Chen Chen;Hersey, Peter
目的：鉴于丝裂原活化蛋白（MAP）/细胞外信号调节激酶（ERK）激酶（MEK）的抑制剂正被引入黑色素瘤的治疗中，进行本研究以更好地理解它们可以诱导黑色素瘤细胞凋亡的机制。评估一组人黑素瘤细胞系和新鲜黑素瘤分离物对MEK抑制剂U 0126诱导的细胞凋亡的敏感性。使用的抑制剂和小干扰RNA（siRNA）techniques.Results：MEK的抑制诱导的凋亡，在大多数的黑色素瘤细胞系通过线粒体途径，与Bax和巴克的激活，释放线粒体促凋亡蛋白，并激活caspase-3的凋亡途径和调控机制进行了研究。然而，细胞凋亡是独立的半胱天冬酶，而是与线粒体释放的AIF，如通过抑制细胞凋亡时，AIF被敲低的siRNA。MEK的抑制导致BH 3-only蛋白MkA和Bim的上调以及抗凋亡蛋白Mcl-1的下调。这些变化对于U 0126诱导细胞凋亡是至关重要的，因为siRNA敲低MkA或Bim抑制细胞凋亡，而siRNA敲低Mcl-1增加细胞凋亡，特别是在抗凋亡细胞系中。通过抑制MEK/ERK途径诱导的黑素瘤细胞凋亡是通过上调/激活MclA和Bim以及下调Mcl-1介导的。AIF的释放而不是半胱天冬酶的激活似乎是细胞凋亡的介导者。我们的研究结果表明，共同靶向Mcl-1和MEK/ERK通路可能会进一步改善黑色素瘤的治疗效果。
Purpose: Given that inhibitors of mitogen- activated protein (MAP)/extracellular signal-regulated kinase (ERK) kinase (MEK) are being introduced into treatment for melanoma, the present study was carried out to better understand the mechanism by which they may induce apoptosis of melanoma cells.Experimental Design: A panel of human melanoma cell lines and fresh melanoma isolates was assessed for their sensitivity to apoptosis induced by the MEK inhibitor U0126. The apoptotic pathways and regulatory mechanisms involved were examined by use of the inhibitor and small interfering RNA (siRNA) techniques.Results: Inhibition of MEK induced apoptosis in the majority of melanoma cell lines through a mitochondrial pathway that was associated with the activation of Bax and Bak, release of mitochondrial apoptogenic proteins, and activation of caspase-3. However, apoptosis was independent of caspases and instead was associated with mitochondrial release of AIF as shown by the inhibition of apoptosis when AIF was knocked down by si RNA. Inhibition of MEK resulted in the up-regulation of the BH3-only proteins PUMA and Bim and down-regulation of the antiapoptotic protein Mcl-1.These changes were critical for the induction of apoptosis by U0126 as siRNA knockdown of PUMA or Bim inhibited apoptosis, whereas siRNA knockdown of Mcl-1 increased apoptosis particularly in the apoptosis-resistant cell lines.Conclusions: Apoptosis of melanoma cells induced by the inhibition of the MEK/ERK pathway is mediated by the up-regulation /activation of PUMA and Bim and down-regulation of Mcl-1. Release of AIF rather than the activation of caspases seems to be the mediator of apoptosis. Our results suggest that cotargeting Mcl-1 and the MEK/ERK pathway may further improve treatment results in melanoma.