Alternative Splicing of EZH2 pre-mRNA by SF3B3 Contributes to the Tumorigenic Potential of Renal Cancer.
Alternative Splicing of EZH2 pre-mRNA by SF3B3 Contributes to the Tumorigenic Potential of Renal Cancer.
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SF3B3 对 EZH2 前体 mRNA 的选择性剪接有助于肾癌的致瘤潜力
DOI：
10.1158/1078-0432.ccr-16-2020
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发表时间：
2017-07-01
期刊：
影响因子：
--
通讯作者：
Ye Z
中科院分区：
文献类型：
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作者：
Chen K;Xiao H;Zeng J;Yu G;Zhou H;Huang C;Yao W;Xiao W;Hu J;Guan W;Wu L;Huang J;Huang Q;Xu H;Ye Z
目的：EZH 2基因的失调或突变导致各种肿瘤，包括透明细胞肾细胞癌（ccRCC）。虽然已经鉴定了EZH 2的几种剪接变体，但关于EZH 2剪接如何调节或选择性剪接对其促肿瘤功能的贡献知之甚少。实验设计：我们采用RT-PCR、Western blot和IHC技术检测了EZH 2及其可变剪接转录本在肾癌组织和肾癌细胞系中的表达。通过CCK 8、Transwell试验和小鼠异种移植实验评估表现出EZH 2或其剪接因子SF 3B 3敲低的肾癌细胞的增殖、迁移、克隆形成性和致瘤性。结果：我们发现，在ccRCC样品和肾癌细胞系中，EZH 2外显子14的包含显著增加。在ccRCC系中，在异种移植模型中，EZH 2 Δ14的增强表达抑制细胞生长、迁移、增殖和致瘤性，而EZH 2促进细胞生长、迁移、增殖和致瘤性。机制研究表明，EZH 2 Δ14同种型作为全长EZH 2的显性负性抑制剂发挥作用。EZH 2 Δ14变体与全长EZH 2的共表达不仅消除了DAB 2 IP和HOXA 9抑制，而且抑制了EZH 2驱动的肿瘤发生。引人注目的是，剪接因子SF 3B 3刺激外显子14的包含并具有促增殖活性。重要的是，在临床ccRCC样品中观察到的SF 3B 3表达的上调与EZH 2外显子14的包含增加平行，并且SF 3B 3水平与较高的肿瘤分期和较差的总生存期相关。结论：这些结果表明SF 3B 3是EZH 2前mRNA剪接的关键调节因子，SF 3B 3可能代表ccRCC中的新预后因子和潜在治疗靶点。临床癌症研究; 23（13）; 3428-41。©2016 AACR.
Purpose: Deregulation or mutation of the EZH2 gene causes various tumors, including clear cell renal cell carcinoma (ccRCC). Although several splice variants of EZH2 have been identified, little is known about how EZH2 splicing is regulated or the contribution of alternative splicing to its protumorigenic functions. Experimental Design: We conducted RT-PCR, Western blot analysis, and IHC techniques to examine EZH2 and its alternative splicing transcript expression in renal cancer tissue and renal cancer cell lines. Proliferation, migration, clonogenicity, and tumorigenicity of renal cancer cells either exhibiting knockdown of EZH2 or its splicing factor SF3B3 were assessed by CCK8, Transwell assay, and murine xenograft experiments. Results: We found that the inclusion of alternative EZH2 exon 14 was significantly increased in ccRCC samples and renal cancer cell lines. In ccRCC lines, enforced expression of EZH2Δ14 inhibited, and EZH2 promoted, cell growth, migration, proliferation, and tumorigenicity in a xenograft model. Mechanistic studies demonstrated that EZH2Δ14 isoform functions as a dominant-negative inhibitor of full-length EZH2. Coexpression of EZH2Δ14 variant with full-length EZH2 not only abrogated DAB2IP and HOXA9 suppression but also inhibited EZH2-driven tumorigenesis. Strikingly, the splicing factor SF3B3 stimulates inclusion of exon14 and has pro-proliferative activity. Importantly, the upregulation of SF3B3 expression observed in clinical ccRCC samples parallels the increased inclusion of EZH2 exon14, and the SF3B3 level is associated with higher tumor stage and poor overall survival. Conclusions: These results suggest SF3B3 as a key regulator of EZH2 pre-mRNA splicing and SF3B3 may represent a novel prognostic factor and potential therapeutic target in ccRCC. Clin Cancer Res; 23(13); 3428–41. ©2016 AACR.