EYA2 通过 SOCS3 介导的 JAK/STAT 信号阻断抑制肝细胞癌的进展。
EYA2 suppresses the progression of hepatocellular carcinoma via SOCS3-mediated blockade of JAK/STAT signaling.
机构信息
National Translational Science Center for Molecular Medicine, Department of Cell Biology, State Key Laboratory of Cancer Biology, Fourth Military Medical University, Xi'an, 710032, China.
School of Life Sciences, Central China Normal University, Wuhan, 430079, China.
出版信息
Mol Cancer. 2021 May 27;20(1):79. doi: 10.1186/s12943-021-01377-9.
BACKGROUND
Somatic mutations are involved in hepatocellular carcinoma (HCC) progression, but the genetic mechanism associated to hepatocarcinogenesis remains poorly understood. We report that Eyes absent homolog 2 (EYA2) suppresses the HCC progression, while EYA2(A510E) mutation identified by exome sequencing attenuates the tumor-inhibiting effect of EYA2.
METHODS
Whole-exome sequencing was performed on six pairs of human HCC primary tumors and matched adjacent tissues. Focusing on EYA2, expression level of EYA2 in human HCC samples was evaluated by quantitative real-time PCR, western blot and immunohistochemistry. Loss- and gain-of-function studies, hepatocyte-specific deletion of EYA2 (Eya2) in mice and RNA sequencing analysis were used to explore the functional effect and mechanism of EYA2 on HCC cell growth and metastasis. EYA2 methylation status was evaluated using Sequenom MassARRAY and publicly available data analysis.
RESULTS
A new somatic mutation p.Ala510Glu of EYA2 was identified in HCC tissues. The expression of EYA2 was down-regulated in HCC and associated with tumor size (P = 0.001), Barcelona Clinic Liver Cancer stage (P = 0.016) and tumor differentiation (P = 0.048). High level of EYA2 was correlated with a favorable prognosis in HCC patients (P = 0.003). Results from loss-of-function and gain-of-function experiments suggested that knockdown of EYA2 enhanced, while overexpression of EYA2 attenuated, the proliferation, clone formation, invasion, and migration of HCC cells in vitro. Delivery of EYA2 gene had a therapeutic effect on inhibition of orthotopic liver tumor in nude mice. However, EYA2(A510E) mutation led to protein degradation by unfolded protein response, thus weakening the inhibitory function of EYA2. Hepatocyte-specific deletion of EYA2 in mice dramatically promoted diethylnitrosamine-induced HCC development. EYA2 was also down-regulated in HCC by aberrant CpG methylation. Mechanically, EYA2 combined with DACH1 to transcriptionally regulate SOCS3 expression, thus suppressing the progression of HCC via SOCS3-mediated blockade of the JAK/STAT signaling pathway.
CONCLUSIONS
In our study, we identified and validated EYA2 as a tumor suppressor gene in HCC, providing a new insight into HCC pathogenesis.
背景
体细胞突变参与肝细胞癌（HCC）的进展，但与肝癌发生相关的遗传机制仍知之甚少。我们报告 Eyes absent 同源物 2（EYA2）抑制 HCC 的进展，而外显子组测序鉴定的 EYA2（A510E）突变削弱了 EYA2 的肿瘤抑制作用。
方法
对六对人 HCC 原发肿瘤及其配对的相邻组织进行全外显子组测序。针对 EYA2，通过定量实时 PCR、western blot 和免疫组织化学评估 EYA2 在人 HCC 样本中的表达水平。采用功能丧失和获得功能研究、小鼠肝细胞特异性 EYA2 缺失（Eya2）和 RNA 测序分析来探讨 EYA2 对 HCC 细胞生长和转移的功能影响和机制。使用 Sequenom MassARRAY 和公开可用数据分析评估 EYA2 甲基化状态。
结果
在 HCC 组织中发现了 EYA2 的新体细胞突变 p.Ala510Glu。EYA2 的表达在 HCC 中下调，与肿瘤大小（P=0.001）、巴塞罗那临床肝癌分期（P=0.016）和肿瘤分化（P=0.048）相关。高水平的 EYA2 与 HCC 患者的良好预后相关（P=0.003）。功能丧失和获得功能实验的结果表明，EYA2 敲低增强，而 EYA2 过表达减弱 HCC 细胞在体外的增殖、克隆形成、侵袭和迁移。EYA2 基因的递送对裸鼠原位肝肿瘤的抑制具有治疗作用。然而，EYA2（A510E）突变导致未折叠蛋白反应引起的蛋白降解，从而削弱了 EYA2 的抑制功能。在小鼠中肝细胞特异性缺失 EYA2 可显著促进二乙基亚硝胺诱导的 HCC 发展。异常的 CpG 甲基化也导致 HCC 中 EYA2 的下调。从机制上讲，EYA2 与 DACH1 结合以转录调控 SOCS3 的表达，从而通过 SOCS3 介导的阻断 JAK/STAT 信号通路抑制 HCC 的进展。
结论
在本研究中，我们鉴定并验证了 EYA2 是 HCC 的肿瘤抑制基因，为 HCC 的发病机制提供了新的见解。
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