Fibronectin induction abrogates the BRAF inhibitor response of BRAF V600E/PTEN-null melanoma cells.
Fibronectin induction abrogates the BRAF inhibitor response of BRAF V600E/PTEN-null melanoma cells.
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DOI：
10.1038/onc.2015.188
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发表时间：
2016-03-10
期刊：
影响因子：
8
通讯作者：
Smalley KS
中科院分区：
文献类型：
--
作者：
Fedorenko IV;Abel EV;Koomen JM;Fang B;Wood ER;Chen YA;Fisher KJ;Iyengar S;Dahlman KB;Wargo JA;Flaherty KT;Sosman JA;Sondak VK;Messina JL;Gibney GT;Smalley KS
一些黑色素瘤细胞适应BRAF抑制剂治疗的机制尚不完全清楚。在本研究中，我们使用基于质谱的磷酸化蛋白质组学来确定BRAF抑制如何重塑BRAF突变和pten缺失的黑色素瘤细胞系的信号网络。短期BRAF抑制与pten依赖性纤维连接蛋白粘附信号的显著变化相关。这些效应通过BRAF siRNA敲低和化疗药物治疗得以重现。在小鼠异种移植模型以及接受BRAF抑制剂治疗的黑色素瘤患者标本中也观察到纤维连接蛋白表达增加。对黑色素瘤TMA的分析显示PTEN表达的缺失预示着较低的总生存率，当分析中包括纤维连接蛋白的缺失时，可以看到更低的生存率趋势。从机制上讲，纤维连接蛋白的诱导限制了这些pten缺失的黑色素瘤细胞系对vemurafenib的反应，在纤维连接蛋白或其受体α5β1整合素的敲除后，观察到细胞毒性增强。这进而通过增加AKT信号通路消除了对BRAF抑制的细胞毒性反应，AKT信号通路通过维持促存活蛋白Mcl-1的表达来阻止细胞死亡的诱导。诱导纤维连接蛋白表达所传递的保护作用可以通过BRAF和PI3K抑制剂联合治疗来克服。
The mechanisms by which some melanoma cells adapt to BRAF inhibitor therapy are incompletely understood. In the present study, we used mass spectrometry-based phosphoproteomics to determine how BRAF inhibition remodeled the signaling network of melanoma cell lines that were BRAF-mutant and PTEN-null. Short-term BRAF inhibition was associated with marked changes in fibronectin-based adhesion signaling that were PTEN-dependent. These effects were recapitulated through BRAF siRNA knockdown and following treatment with chemotherapeutic drugs. Increased fibronectin expression was also observed in mouse xenograft models as well as specimens from melanoma patients undergoing BRAF inhibitor treatment. Analysis of a melanoma TMA showed loss of PTEN expression to predict for a lower overall survival, with a trend for even lower survival being seen when loss of fibronectin was included in the analysis. Mechanistically, the induction of fibronectin limited the responses of these PTEN-null melanoma cell lines to vemurafenib, with enhanced cytotoxicity observed following the knockdown of either fibronectin or its receptor α5β1 integrin. This in turn abrogated the cytotoxic response to BRAF inhibition via increased AKT signaling, which prevented the induction of cell death by maintaining the expression of the pro-survival protein Mcl-1. The protection conveyed by the induction of fibronectin expression could be overcome through combined treatment with a BRAF and PI3K inhibitor.