BACKGROUND Hepatic metastasis develops in ~ 50% of uveal melanoma (UM) patients with no effective treatments. Although GNAQ/GNA11 mutations are believed to confer pathogenesis of UM, the underlying mechanism of liver metastasis remains poorly understood. Given that profound epigenetic evolution may occur in the long journey of circulating tumor cells (CTCs) to distant organs, we hypothesized that EZH2 endowed tumor cells with enhanced malignant features (e.g., stemness and motility) during hepatic metastasis in UM. We aimed to test this hypothesis and explore whether EZH2 was a therapeutic target for hepatic metastatic UM patients. METHODS Expression of EZH2 in UM was detected by qRT-PCR, Western blotting and immunohistochemistry staining. Proliferation, apoptosis, cancer stem-like cells (CSCs) properties, migration and invasion were evaluated under circumstances of treatment with either EZH2 shRNA or EZH2 inhibitor GSK126. Antitumor activity and frequency of CSCs were determined by xenografted and PDX models with NOD/SCID mice. Hepatic metastasis was evaluated with NOG mice. RESULTS We found that EZH2 overexpressed in UM promoted the growth of UM; EZH2 increased the percentage and self-renewal of CSCs by miR-29c-DVL2-β-catenin signaling; EZH2 facilitates migration and invasion of UM cells via RhoGDIγ-Rac1 axis. Targeting EZH2 either by genetics or small molecule inhibitor GSK126 decreased CSCs and motility and abrogated the liver metastasis of UM. CONCLUSIONS These findings validate EZH2 as a druggable target in metastatic UM patients, and may shed light on the understanding and interfering the complicated metastatic process.

中文翻译：

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验证EZH2作为转移性葡萄膜黑色素瘤的可治疗靶标。

背景技术在没有有效治疗的葡萄膜黑色素瘤（UM）患者中，约50％发生肝转移。尽管GNAQ / GNA11突变被认为可引起UM的发病机制，但对肝转移的潜在机制仍知之甚少。鉴于在循环肿瘤细胞（CTC）向远处器官的漫长旅途中可能发生深远的表观遗传进化，我们假设EZH2赋予肿瘤细胞在UM肝转移期间具有增强的恶性特征（例如，干性和运动性）。我们旨在验证这一假设，并探讨EZH2是否是肝转移性UM患者的治疗靶标。方法采用qRT-PCR，Western blotting和免疫组化染色检测EZH2在UM中的表达。增殖，凋亡，癌干样细胞（CSC）特性，在使用EZH2 shRNA或EZH2抑制剂GSK126治疗的情况下评估了迁移和侵袭。通过异种移植和PDX模型对NOD / SCID小鼠确定CSCs的抗肿瘤活性和频率。用NOG小鼠评估肝转移。结果我们发现在UM中过表达的EZH2促进了UM的生长。EZH2通过miR-29c-DVL2-β-catenin信号传导增加CSC的百分比和自我更新；EZH2通过RhoGDIγ-Rac1轴促进UM细胞的迁移和侵袭。通过遗传学或小分子抑制剂GSK126靶向EZH2可降低CSC和运动能力，并消除UM的肝转移。结论这些发现证实EZH2是转移性UM患者的可治疗靶标，并可能有助于理解和干扰复杂的转移过程。