University of California San Diego, Moores Cancer Center, La Jolla, California, USA; University of California San Diego, Biomedical Sciences Graduate Program, La Jolla, California, USA; Department of Pharmacology, University of California San Diego, School of Medicine, La Jolla, California, USA.
University of California San Diego, Moores Cancer Center, La Jolla, California, USA; Department of Pharmacy, University of Pisa, Pisa, Italy.
J Biol Chem. 2023 Feb;299(2):102866. doi: 10.1016/j.jbc.2022.102866. Epub 2022 Dec 31.
G proteins and G protein-coupled receptors activate a diverse array of signal transduction pathways that promote cell growth and survival. Indeed, hot spot-activating mutations in GNAQ/GNA11, encoding Gαq proteins, are known to be driver oncogenes in uveal melanoma (UM), for which there are limited effective therapies currently available. Focal adhesion kinase (FAK) has been recently shown to be a central mediator of Gαq-driven signaling in UM, and as a result, is being explored clinically as a therapeutic target for UM, both alone and in combination therapies. Despite this, the repertoire of Gαq/FAK-regulated signaling mechanisms have not been fully elucidated. Here, we used a whole-genome CRISPR screen in GNAQ-mutant UM cells to identify mechanisms that, when overactivated, lead to reduced sensitivity to FAK inhibition. In this way, we found that the PI3K/AKT signaling pathway represented a major resistance driver. Our dissection of the underlying mechanisms revealed that Gαq promotes PI3K/AKT activation via a conserved signaling circuitry mediated by FAK. Further analysis demonstrated that FAK activates PI3K through the association and tyrosine phosphorylation of the p85 regulatory subunit of PI3K and that UM cells require PI3K/AKT signaling for survival. These findings establish a novel link between Gαq-driven signaling and the stimulation of PI3K as well as demonstrate aberrant activation of signaling networks underlying the growth and survival of UM and other Gαq-driven malignancies.
G 蛋白和 G 蛋白偶联受体激活了多种信号转导途径，促进了细胞的生长和存活。事实上，编码 Gαq 蛋白的 GNAQ/GNA11 中的热点激活突变被认为是葡萄膜黑色素瘤 (UM) 的驱动致癌基因，目前针对这种疾病的有效治疗方法有限。最近的研究表明，粘着斑激酶 (FAK) 是 UM 中 Gαq 驱动信号的核心介质，因此，FAK 作为 UM 的治疗靶点，无论是单独使用还是联合治疗，都正在临床上进行探索。尽管如此，Gαq/FAK 调节的信号机制尚未完全阐明。在这里，我们使用 GNAQ 突变的 UM 细胞中的全基因组 CRISPR 筛选来鉴定当过度激活时会导致对 FAK 抑制敏感性降低的机制。通过这种方式，我们发现 PI3K/AKT 信号通路代表了主要的耐药驱动因素。我们对潜在机制的剖析表明，Gαq 通过由 FAK 介导的保守信号通路促进 PI3K/AKT 的激活。进一步的分析表明，FAK 通过 PI3K 的 p85 调节亚基的关联和酪氨酸磷酸化激活 PI3K，并且 UM 细胞的存活需要 PI3K/AKT 信号。这些发现确立了 Gαq 驱动的信号与 PI3K 刺激之间的新联系，并证明了 UM 和其他 Gαq 驱动的恶性肿瘤的生长和存活所依赖的信号网络的异常激活。
