Cancer-associated mutations in the guanosine triphosphatase (GTPase) RHOA are found at different locations from the mutational hotspots in the structurally and biochemically related RAS. Tyr 42 -to-Cys (Y42C) and Leu 57 -to-Val (L57V) substitutions are the two most prevalent RHOA mutations in diffuse gastric cancer (DGC). RHOA Y42C exhibits a gain-of-function phenotype and is an oncogenic driver in DGC. Here, we determined how RHOA L57V promotes DGC growth. In mouse gastric organoids with deletion of Cdh1 , which encodes the cell adhesion protein E-cadherin, the expression of RHOA L57V , but not of wild-type RHOA, induced an abnormal morphology similar to that of patient-derived DGC organoids. RHOA L57V also exhibited a gain-of-function phenotype and promoted F-actin stress fiber formation and cell migration. RHOA L57V retained interaction with effectors but exhibited impaired RHOA-intrinsic and GAP-catalyzed GTP hydrolysis, which favored formation of the active GTP-bound state. Introduction of missense mutations at KRAS residues analogous to Tyr 42 and Leu 57 in RHOA did not activate KRAS oncogenic potential, indicating distinct functional effects in otherwise highly related GTPases. Both RHOA mutants stimulated the transcriptional co-activator YAP1 through actin dynamics to promote DGC progression; however, RHOA L57V additionally did so by activating the kinases IGF1R and PAK1, distinct from the FAK-mediated mechanism induced by RHOA Y42C . Our results reveal that RHOA L57V and RHOA Y42C drive the development of DGC through distinct biochemical and signaling mechanisms.

中文翻译：

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RHOA L57V 通过 IGF1R-PAK1-YAP1 信号传导驱动弥漫性胃癌的发展

鸟苷三磷酸酶 (GTPase) RHOA 中与癌症相关的突变与结构和生化相关 RAS 中的突变热点位于不同的位置。提尔42-to-Cys (Y42C) 和 Leu57-to-Val (L57V) 替换是弥漫性胃癌 (DGC) 中两种最常见的 RHOA 突变。罗奥Y42C表现出功能获得表型，并且是 DGC 的致癌驱动因素。在这里，我们确定了 RHOA 如何L57V促进 DGC 生长。在小鼠胃类器官中，缺失CDH1，编码细胞粘附蛋白E-钙粘蛋白，RHOA的表达L57V，但不是野生型 RHOA，诱导了与患者来源的 DGC 类器官相似的异常形态。罗奥L57V还表现出功能获得表型并促进 F-肌动蛋白应力纤维形成和细胞迁移。罗奥L57V保留了与效应子的相互作用，但表现出 RHOA 固有的和 GAP 催化的 GTP 水解受损，这有利于活性 GTP 结合状态的形成。在类似于 Tyr 的 KRAS 残基处引入错义突变42和亮氨酸57RHOA 中的 GTP 酶不会激活 KRAS 致癌潜力，这表明在其他高度相关的 GTP 酶中存在明显的功能效应。两种 RHOA 突变体均通过肌动蛋白动力学刺激转录共激活因子 YAP1，从而促进 DGC 进展；然而，罗奥L57V另外，通过激活激酶 IGF1R 和 PAK1 来实现这一点，这与 RHOA 诱导的 FAK 介导机制不同Y42C。我们的结果表明 RHOAL57V和罗奥Y42C通过独特的生化和信号机制驱动 DGC 的发展。