Targeting Gq pathway in uveal melanoma

项目概要： 葡萄膜黑色素瘤（UM）是美国最常见的眼内癌症， 占所有黑色素瘤的5%。大约50%的UM患者发生转移，主要转移至肝脏 死亡率百分之百UM缺乏其他黑色素瘤类型常见的BRAF、NRAS、NF 1和KIT突变。 相反，超过90%的人在Gaq家族成员GNAQ或GNA 11中携带体细胞激活突变， 其余携带也在Gaq信号传导途径中起作用的基因突变，如CYSLTR 2，一种Gaq- 偶联GPCR，磷脂酶Cb 4（PLCb 4），Gaq的直接效应物。因此，UM在基因上被定义为 激活Gaq途径的突变。尽管在其他黑色素瘤亚型中取得了巨大的成功，但免疫 检查点抑制剂和靶向治疗未能证明UM的临床益处，导致 迫切需要开发新的和有效的治疗方案。CYSLTR 2->Gaq->PLCb->蛋白激酶 蛋白激酶C（PKC）模块是一个线性信号级联反应，驱动UM细胞必需的MAPK信号通路 增殖，使Gaq途径成为这种毁灭性疾病靶向治疗的主要靶点。虽然两 GNAQ/11和PKC抑制剂在体外非常有效地抑制UM细胞增殖/存活，靶向 GNAQ/11或PKC单独在UM肝转移中显示出有限的功效。了解对 抑制Gaq通路对于开发在特异性信号传导中起作用的新策略至关重要 在组成性激活的Gaq途径的背景下。我们的初步数据显示，GNAQ/11抑制或PKC 抑制产生Gaq偶联受体EDNRB的强烈上调，当遇到其配体时， 来自肝脏环境的EDN 1可以导致MAPK的重新激活，从而驱动对Gaq途径的抗性 在UM中抑制。在这个建议中，我们将评估阻断内皮素信号传导将增加治疗效果。 使用新开发的基因工程技术，直接或下游靶向致癌Gaq信号传导的功效 转移到肝脏的UM的工程化和异种移植模型。虽然内皮素信号在 黑素细胞发育和黑色素瘤进展是有据可查的， 上调EDNRB表达/信号传导尚不清楚。我们将利用候选人的组合 方法，RNAseq和磷酸化蛋白质组学来剖析UM细胞中的潜在机制， 黑素细胞我们的初步数据还表明，GNA 11中的继发性突变可以赋予对GNA 11的耐药性。 Gaq抑制。在本提案中，我们将扩大作为《公约》基础的机制的新格局， 对Gaq通路抑制的适应性和获得性耐药性，并确定合理的治疗组合，以改善 转移性UM的治疗效果。使用组合的全基因组CRISPR/Cas9合成致死性 筛选和磷酸化蛋白质组学筛选，我们确定了一个脂质合成途径，这是必不可少的生存， Gaq突变的细胞，我们将探索作为UM的全新治疗靶点。

Project summary: Uveal melanoma (UM) is the most common intraocular cancer in the United States and accounts for about 5% of all kinds of melanomas. Approximate 50% of UM patients develop metastases, predominantly to the liver with 100% mortality. UM lacks mutations in BRAF, NRAS, NF1 and KIT common to other melanoma types. Instead, over 90% harbor somatic activating mutations in the Gaq family members GNAQ or GNA11, with the remainder carrying mutations of genes also acting in the Gaq signaling pathway such as CYSLTR2, a Gaq- coupled GPCR, phospholipases C b4 (PLCb4), a direct effector of Gaq. Therefore, UM is genetically defined by activating mutations of the Gaq pathway. Despite dramatic successes in other melanoma subtypes, immune checkpoint inhibitors and targeted therapies have failed to demonstrate clinical benefits in UM, leading to an urgent need to develop novel and effective therapeutic regimens. The CYSLTR2->Gaq->PLCb-> protein kinase C (PKC) module is a linear signaling cascade that drives the essential MAP-kinase (MAPK) signaling for UM cell proliferation, making Gaq pathway the prime target for targeted therapy for this devasting disease. Although both GNAQ/11 and PKC inhibitors are very effective to suppress UM cell proliferation/survival in vitro, targeting either GNAQ/11 or PKC alone has shown limited efficacy in UM liver metastasis. Understanding the resistance to the Gaq pathway inhibition is of paramount importance to develop new strategies that work in the specific signaling context of a constitutively activated Gaq pathway. Our preliminary data show either GNAQ/11 inhibition or PKC inhibition yields strong upregulation of the Gaq-coupled receptor EDNRB, which when encountering its ligand EDN1 from the liver environment can lead to reactivation of MAPK, thus driving resistance to Gaq pathway inhibition in UM. In this proposal, we will evaluate that blocking endothelin signaling will increase the therapeutic efficacy of targeting oncogenic Gaq signaling, directly or downstream, using newly developed genetically engineered and xenograft models of UM metastatic to the liver. While the role of endothelin signaling in melanocyte development and melanoma progression is well documented, the nature of the feedback that upregulates EDNRB expression/signaling is not understood. We will utilize a combination of candidate approaches, RNAseq and phospho-proteomics to dissect the underlying mechanisms in UM cells and in melanocytes. Our preliminary data also show that secondary mutations in GNA11 can confer resistance to the Gaq inhibition. In this proposal, we will expand the emerging landscape of the mechanism underlying the adaptive and acquired resistance to Gaq pathway inhibition and identify rational therapy combinations to improve the therapeutic efficacy for metastatic UM. Using a combined genome-wide CRISPR/Cas9 synthetic lethality screen and phospho-proteomic screen we identified a lipid synthesis pathway that is essential for the survival of cells with Gaq mutation, which we will explore as entirely novel therapeutic target for UM.