RASSF1A Directly Antagonizes RhoA Activity through the Assembly of a Smurf1-Mediated Destruction Complex to Suppress Tumorigenesis
RASSF1A Directly Antagonizes RhoA Activity through the Assembly of a Smurf1-Mediated Destruction Complex to Suppress Tumorigenesis
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DOI：
10.1158/0008-5472.can-15-1752
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发表时间：
2016-04-01
期刊：
影响因子：
11.2
通讯作者：
Chi, Sung-Gil
中科院分区：
文献类型：
--
作者：
Lee, Min-Goo;Jeong, Seong-In;Chi, Sung-Gil
RASSF1A是一种与许多致瘤过程有关的肿瘤抑制因子；然而，其肿瘤抑制功能的基础尚不完全清楚。本研究表明，RASSF1A是一种新型的致瘤性RhoA活性拮抗剂。RASSF1A的c端氨基酸（256-277）与活性GTP-RhoA之间的直接相互作用对这种拮抗作用至关重要。此外，RASSF1A的n端氨基酸（69-82）与泛素E3连接酶Smad泛素化调节因子1 （Smurf1）之间的相互作用通过促进Smurf1介导的GTP-RhoA泛素化来破坏GTPase的活性。我们注意到RASSF1A的RhoA结合域与其他RhoA效应体（如Rhotekin）中的RhoA结合基序具有高度的序列同源性。正如在此基础上预测的那样，RASSF1A与Rhotekin竞争结合RhoA并阻断其激活。无法结合RhoA或Smurf1的RASSF1A突变体无法抑制RhoA诱导的肿瘤细胞增殖、耐药、上皮-间质转化、迁移、侵袭和转移。在临床上，RASSF1A和RhoA的表达水平在许多类型的原发性和转移性肿瘤和肿瘤细胞系中呈负相关。总的来说，我们的研究结果表明RASSF1A如何通过内在地抑制RhoA的促肿瘤活性来抑制肿瘤发生，从而阐明了RASSF1A失活在许多癌症中的潜在机制后果。
RASSF1A is a tumor suppressor implicated in many tumorigenic processes; however, the basis for its tumor suppressor functions are not fully understood. Here we show that RASSF1A is a novel antagonist of protumorigenic RhoA activity. Direct interaction between the C-terminal amino acids (256-277) of RASSF1A and active GTP-RhoA was critical for this antagonism. In addition, interaction between the N-terminal amino acids (69-82) of RASSF1A and the ubiquitin E3 ligase Smad ubiquitination regulatory factor 1 (Smurf1) disrupted GTPase activity by facilitating Smurf1-mediated ubiquitination of GTP-RhoA. We noted that the RhoA-binding domain of RASSF1A displayed high sequence homology with Rho-binding motifs in other RhoA effectors, such as Rhotekin. As predicted on this basis, RASSF1A competed with Rhotekin to bind RhoA and to block its activation. RASSF1A mutants unable to bind RhoA or Smurf1 failed to suppress RhoA-induced tumor cell proliferation, drug resistance, epithelial-mesenchymal transition, migration, invasion, and metastasis. Clinically, expression levels of RASSF1A and RhoA were inversely correlated in many types of primary and metastatic tumors and tumor cell lines. Collectively, our findings showed how RASSF1A may suppress tumorigenesis by intrinsically inhibiting the tumor-promoting activity of RhoA, thereby illuminating the potential mechanistic consequences of RASSF1A inactivation in many cancers.