BH3 mimetics potentiate pro-apoptotic activity of encorafenib in BRAFV600E melanoma cells
BH3 mimetics potentiate pro-apoptotic activity of encorafenib in BRAFV600E melanoma cells
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DOI：
10.1016/j.canlet.2020.11.036
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发表时间：
2021-02-28
期刊：
影响因子：
9.7
通讯作者：
Czyz, Malgorzata
中科院分区：
文献类型：
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作者：
Hartman, Mariusz L.;Gajos-Michniewicz, Anna;Czyz, Malgorzata
BRAF（V600）和MEK 1/2靶向治疗很少在黑色素瘤患者中产生持久的反应。我们研究了5个BRAF（V600 E）黑色素瘤细胞系，这些细胞系来源于未用药的肿瘤标本，以评估对最近FDA批准的BRAF（V600）抑制剂Encorafenib（Braftovi）的细胞死亡反应。未用药细胞系（i）在编码核心凋亡机制的基因中没有破坏性改变，但它们在（ii）线粒体引发（如全细胞BH 3谱所示）和（iii）所选抗凋亡蛋白的水平方面存在差异。Encorafenib调节凋亡调节蛋白之间的平衡，因为它上调BIM和BMF，并减弱NOXA，但不影响所选细胞系中除MCL-1和BCL-XL外的促存活蛋白的水平。细胞凋亡的诱导可以使用动态BH 3谱来预测。细胞凋亡的程度取决于（i）细胞内在接近凋亡阈值（初始线粒体启动）和（ii）Encorafenib诱导的BIM（iBIM;药物诱导的启动变化）的丰度。虽然MCL 1和BCL-X-L/BCL-2的共抑制对于药物初始细胞中的细胞凋亡是必不可少的，但Encorafenib改变了细胞对MCL-1的依赖性，并且在Encorafenib高度引发细胞凋亡的细胞系中还发现了对BCL-X-L/BCL-2的依赖性。当恩可非尼与选择性BH 3模拟物组合时，这转化为稳健的细胞凋亡。我们的研究提供了对BCL-2家族蛋白质在黑色素瘤细胞对靶向治疗的反应中的作用的机制性见解，并提供了临床前证据，即（i）MCL-1是增强恩可拉非尼活性的可药用靶标，而（ii）BCL-X-L/BCL-2的药理学抑制可能相关，但仅适用于一小部分恩可拉非尼治疗的患者。
BRAF(V600)- and MEK1/2-targeting therapies rarely produce durable response in melanoma patients. We investigated five BRAF(V600E) melanoma cell lines derived from drug-naive tumor specimens to assess cell death response to encorafenib (Braftovi), a recently FDA-approved BRAF(V600) inhibitor. Drug-naive cell lines (i) did not harbor damaging alterations in genes encoding core apoptotic machinery, but they differed in (ii) mitochondrial priming as demonstrated by whole-cell BH3 profiling, and (iii) levels of selected anti-apoptotic proteins. Encorafenib modulated the balance between apoptosis-regulating proteins as it upregulated BIM and BMF, and attenuated NOXA, but did not affect the levels of pro-survival proteins except for MCL-1 and BCL-XL in selected cell lines. Induction of apoptosis could be predicted using Dynamic BH3 profiling. The extent of apoptosis was dependent on both (i) cell-intrinsic proximity to the apoptotic threshold (initial mitochondrial priming) and (ii) the abundance of encorafenib-induced BIM (iBIM; drug-induced change in priming). While co-inhibition of MCL1 and BCL-X-L/BCL-2 was indispensable for apoptosis in drug-naive cells, encorafenib altered cell dependence to MCL-1, and reliance on BCL-X-L/BCL-2 was additionally found in cell lines that were highly primed to apoptosis by encorafenib. This translated into robust apoptosis when encorafenib was combined with selective BH3 mimetics. Our study provides a mechanistic insight into the role of proteins from the BCL-2 family in melanoma cell response to targeted therapy, and presents preclinical evidence that (i) MCL-1 is a druggable target to potentiate encorafenib activity, whereas (ii) pharmacological inhibition of BCL-X-L/BCL-2 might be relevant but only for a narrow group of encorafenib-treated patients.