RPPA-based protein profiling reveals eIF4G overexpression and 4E-BP1 serine 65 phosphorylation as molecular events that correspond with a pro-survival phenotype in chronic lymphocytic leukemia.
RPPA-based protein profiling reveals eIF4G overexpression and 4E-BP1 serine 65 phosphorylation as molecular events that correspond with a pro-survival phenotype in chronic lymphocytic leukemia.
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DOI：
10.18632/oncotarget.4104
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发表时间：
2015-06-10
期刊：
影响因子：
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通讯作者：
Shi H
中科院分区：
文献类型：
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作者：
Shull AY;Noonepalle SK;Awan FT;Liu J;Pei L;Bollag RJ;Salman H;Ding Z;Shi H
慢性淋巴细胞白血病（CLL）是最常见的成人白血病，尽管在过去十年中治疗方案取得了进展，但仍然无法治愈。为了更好地了解CLL的发病机制，已经进行了一些表达谱研究。然而，这些大规模的研究只提供了转录水平的信息。为了更好地理解CLL中发生的差异蛋白变化，我们对来自18名CLL患者和6名正常供者的b细胞裂解物进行了167种不同抗体的反相蛋白阵列（RPPA）分析。从我们的分析中，我们发现与mRNA翻译相关的蛋白质改变富集，特别是翻译启动子eIF4G的上调和帽依赖性翻译抑制剂4E-BP1丝氨酸65的磷酸化。有趣的是，4E-BP1磷酸化独立于AKT磷酸化发生，这表明PI3K/AKT通路激活与4E-BP1磷酸化之间存在脱节。基于这些结果，我们用PI3K/mTOR双抑制剂NVP-BEZ235处理原发性CLL样本，并比较其对BTK抑制剂Ibrutinib和PI3Kδ抑制剂Idelalisib的诱导凋亡潜能。我们证明，NVP-BEZ235在原代CLL细胞中引起更大的凋亡，更大的eIF4G凋亡切割和更大的4E-BP1去磷酸化。综上所述，这些结果强调了eIF4G过表达和4E-BP1磷酸化在CLL生存中的潜在依赖性。
Chronic lymphocytic leukemia (CLL), the most common adult leukemia, remains incurable despite advancements in treatment regimens over the past decade. Several expression profile studies have been pursued to better understand CLL pathogenesis. However, these large-scale studies only provide information at the transcriptional level. To better comprehend the differential protein changes that take place in CLL, we performed a reverse-phase protein array (RPPA) analysis using 167 different antibodies on B-cell lysates from 18 CLL patients and 6 normal donors. From our analysis, we discovered an enrichment of protein alterations involved with mRNA translation, specifically upregulation of the translation initiator eIF4G and phosphorylation of the cap-dependent translation inhibitor 4E-BP1 at serine 65. Interestingly, 4E-BP1 phosphorylation occurred independently of AKT phosphorylation, suggesting a disconnect between PI3K/AKT pathway activation and 4E-BP1 phosphorylation. Based on these results, we treated primary CLL samples with NVP-BEZ235, a PI3K/mTOR dual inhibitor, and compared its apoptotic-inducing potential against the BTK inhibitor Ibrutinib and the PI3Kδ inhibitor Idelalisib. We demonstrated that treatment with NVP-BEZ235 caused greater apoptosis, greater apoptotic cleavage of eIF4G, and greater dephosphorylation of 4E-BP1 in primary CLL cells. Taken together, these results highlight the potential dependence of eIF4G overexpression and 4E-BP1 phosphorylation in CLL survival.