Ric-8A gene deletion or phorbol ester suppresses tumorigenesis in a mouse model of GNAQ(Q209L)-driven melanoma.
Ric-8A gene deletion or phorbol ester suppresses tumorigenesis in a mouse model of GNAQ(Q209L)-driven melanoma.
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DOI：
10.1038/oncsis.2016.45
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发表时间：
2016-06-27
期刊：
影响因子：
6.2
通讯作者：
Tall GG
中科院分区：
文献类型：
--
作者：
Patel BR;Tall GG
异三聚体G蛋白α亚基癌基因GNAQ或GNA11携带Q209X或R183X激活突变，在人葡萄膜黑色素瘤中存在约90%的频率。GNAQ/11Q209L在黑素细胞中的强制表达足以驱动免疫受损小鼠的转移性黑色素瘤。没有已知的药物直接针对这些致癌的G蛋白。Ric-8A是选择性折叠g - αq/i/13亚基的分子伴侣。靶向Ric-8A是一种合理但尚未被探索的方法，可以降低致癌基因g - αq/11的功能丰度，从而减弱癌症信号传导。通过小鼠黑素细胞移植瘤发生模型，我们确定了rick - 8a基因消融可减弱g - αq- q209l的丰度和黑素瘤驱动潜能。一种新的有条件的ric8aflox /Flox；获得Rosa-CreER+/−小鼠菌株，并将其作为组织源培养永生化，他莫昔芬诱导的ric8a敲除黑素细胞系，该细胞系需要12-O-tetradecanoylphorbol-13-acetate （TPA， phorbol酯）生长。当将该细胞系移植到免疫功能低下的小鼠体内时，无论是否表达ric8a，该细胞系都不能生长肿瘤。在细胞系中稳定表达人GNAQQ209L，而不表达GNAQWT，可促进tpa不依赖的细胞增殖，在小鼠细胞移植后，深色黑色素瘤肿瘤的发生和强劲生长。在GNAQQ209L细胞中缺失ric8a可以恢复tpa依赖性生长，将Gαq-Q209L降低到可检测水平，并完全减轻原代或继代细胞系移植物的肿瘤发生。有趣的是，TPA处理培养的GNAQQ209L细胞或移植GNAQQ209L细胞的宿主动物也显著降低了g - αq- q209l的丰度和致瘤能力。最后，从GNAQQ209L细胞移植物开始肿瘤发生，随后给宿主小鼠全身他莫昔芬治疗以删除移植物细胞中的Ric-8A，完全消除了GNAQQ209L驱动的肿瘤进展，除非使用稳定的人Ric-8A转基因来挽救固定的Ric-8A等位基因。我们的工作定义了两个新的合理靶点，它们可能通过降低Gαq/11-Q209L癌蛋白丰度而发展成为潜在的葡萄膜黑色素瘤治疗方法：(1)抑制Ric-8A和(2)磷酸酯治疗。
The heterotrimeric G protein α subunit oncogenes GNAQ or GNA11 carry Q209X or R183X activating mutations and are present with ~90% frequency in human uveal melanomas. Forced expression of GNAQ/11Q209L in melanocytes is sufficient to drive metastatic melanoma in immune-compromised mice. No known drugs directly target these oncogenic G proteins. Ric-8A is the molecular chaperone that selectively folds Gαq/i/13 subunits. Targeting Ric-8A serves as a rational, yet unexplored approach to reduce the functional abundance of oncogenic Gαq/11 in order to blunt cancer signaling. Here, using mouse melanocyte cell graft tumorigenesis models, we determined that Ric-8A genetic ablation attenuated the abundance and melanoma-driving potential of Gαq-Q209L. A new conditional Ric-8AFlox/Flox; Rosa-CreER+/− mouse strain was derived and used as a tissue source to culture an immortalized, tamoxifen-inducible Ric-8A knockout melanocyte cell line that required 12-O-tetradecanoylphorbol-13-acetate (TPA, phorbol ester) for growth. The cell line failed to grow tumors when grafted into immune-compromised mice regardless of Ric-8A expression. Stable expression of human GNAQQ209L, but not GNAQWT in the cell line promoted TPA-independent cell proliferation, and upon cell grafting in mice, the initiation and robust growth of darkly-pigmented melanoma tumors. Deletion of Ric-8A in GNAQQ209L cells restored TPA-dependent growth, reduced Gαq-Q209L below detectable levels and completely mitigated tumorigenesis from primary or secondary cell line grafts. Interestingly, TPA treatment of cultured GNAQQ209L cells or host animals grafted with GNAQQ209L cells also sharply reduced Gαq-Q209L abundance and tumorigenic capacity. Finally, tumorigenesis initiated from GNAQQ209L cell grafts, followed by host mouse systemic tamoxifen treatment to delete Ric-8A in the grafted cells completely abrogated GNAQQ209L-driven tumor progression unless a stable human RIC-8A transgene was used to rescue the floxed Ric-8A alleles. Our work defines two new rational targets that may be developed as potential uveal melanoma therapies through reduction of Gαq/11-Q209L oncoprotein abundance: (1) Ric-8A inhibition and (2) phorbol ester treatment.