抑制葡萄膜黑色素瘤中的突变 GNAQ 信号诱导 AMPK 依赖性自噬细胞死亡。

Inhibition of mutant GNAQ signaling in uveal melanoma induces AMPK-dependent autophagic cell death.

机构信息

Laboratory of New Drug Development, Department of Medicine, Memorial Sloan-Kettering Cancer Center, New York, NY 10065, USA.

出版信息

Mol Cancer Ther. 2013 May;12(5):768-76. doi: 10.1158/1535-7163.MCT-12-1020. Epub 2013 Feb 26.

Abstract

Oncogenic mutations in GNAQ and GNA11 genes are found in 80% of uveal melanoma. These mutations result in the activation of the RAF/MEK signaling pathway culminating in the stimulation of ERK1/2 mitogen-activated protein kinases. In this study, using a siRNA strategy, we show that mutant GNAQ signals to both MEK and AKT, and that combined inhibition of these pathways with the MEK inhibitor selumetinib (AZD6244) and the AKT inhibitor MK2206 induced a synergistic decrease in cell viability. This effect was genotype dependent as autophagic markers like beclin1 and LC3 were induced in GNAQ-mutant cells, whereas apoptosis was the mechanism of cell death of BRAF-mutant cells, and cells without either mutation underwent cell-cycle arrest. The inhibition of MEK/ATK pathways induced activation of AMP-activated protein kinase (AMPK) in the GNAQ-mutant cells. The downregulation of AMPK by siRNA or its inhibition with compound C did not rescue the cells from autophagy, rather they died by apoptosis, defining AMPK as a key regulator of mutant GNAQ signaling and a switch between autophagy and apoptosis. Furthermore, this combination treatment was effective in inhibiting tumor growth in xenograft mouse models. These findings suggest that inhibition of MEK and AKT may represent a promising approach for targeted therapy of patients with uveal melanoma.

摘要

GNAQ 和 GNA11 基因的致癌突变存在于 80%的葡萄膜黑色素瘤中。这些突变导致 RAF/MEK 信号通路的激活,最终导致 ERK1/2 丝裂原活化蛋白激酶的刺激。在这项研究中,我们使用 siRNA 策略表明,突变的 GNAQ 向 MEK 和 AKT 发出信号,并且用 MEK 抑制剂 selumetinib(AZD6244)和 AKT 抑制剂 MK2206 联合抑制这些通路会导致细胞活力协同下降。这种效应依赖于基因型,因为自噬标记物如 beclin1 和 LC3 在 GNAQ 突变细胞中被诱导,而细胞凋亡是 BRAF 突变细胞的细胞死亡机制,而没有任何突变的细胞则经历细胞周期停滞。MEK/ATK 通路的抑制在 GNAQ 突变细胞中诱导 AMP 激活蛋白激酶 (AMPK) 的激活。siRNA 下调 AMPK 或用化合物 C 抑制 AMPK 并不能使细胞免于自噬,而是通过细胞凋亡死亡,这表明 AMPK 是突变的 GNAQ 信号的关键调节剂和自噬和细胞凋亡之间的转换。此外,这种联合治疗在异种移植小鼠模型中抑制肿瘤生长是有效的。这些发现表明,抑制 MEK 和 AKT 可能代表一种有前途的针对葡萄膜黑色素瘤患者的靶向治疗方法。

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