PHF8 的上调导致肝细胞癌中 E-钙黏蛋白的自噬降解、上皮-间充质转化和转移。
PHF8 upregulation contributes to autophagic degradation of E-cadherin, epithelial-mesenchymal transition and metastasis in hepatocellular carcinoma.
机构信息
Division of Hepatobiliary and Pancreatic Surgery, Department of Surgery, The First Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, China.
NHFPC Key Laboratory of Combined Multi-Organ Transplantation, Hangzhou, China.
出版信息
J Exp Clin Cancer Res. 2018 Sep 4;37(1):215. doi: 10.1186/s13046-018-0890-4.
BACKGROUND
Plant homeodomain finger protein 8 (PHF8) serves an activator of epithelial-mesenchymal transition (EMT) and is implicated in various tumors. However, little is known about PHF8 roles in hepatocellular carcinoma (HCC) and regulating E-cadherin expression.
METHODS
PHF8 expression pattern was investigated by informatic analysis and verified by RT-qPCR and immunochemistry in HCC tissues and cell lines. CCK8, xenograft tumor model, transwell assay, and tandem mCherry-GFP-LC3 fusion protein assay were utilized to assess the effects of PHF8 on proliferation, metastasis and autophagy of HCC cells in vitro and in vivo. ChIP, immunoblot analysis, rescue experiments and inhibitor treatment were used to clarify the mechanism by which PHF8 facilitated EMT, metastasis and autophagy.
RESULTS
PHF8 upregulation was quite prevalent in HCC tissues and closely correlated with worse overall survival and disease-relapse free survival. Furthermore, PHF8-knockdown dramatically suppressed cell growth, migration, invasion and autophagy, and the expression of SNAI1, VIM, N-cadherin and FIP200, and increased E-cadherin level, while PHF8-overexpression led to the opposite results. Additionally, FIP200 augmentation reversed the inhibited effects of PHF8-siliencing on tumor migration, invasion and autophagy. Mechanistically, PHF8 was involved in transcriptionally regulating the expression of SNAI1, VIM and FIP200, rather than N-cadherin and E-cadherin. Noticeably, E-cadherin degradation could be accelerated by PHF8-mediated FIP200-dependent autophagy, a crucial pathway complementary to transcriptional repression of E-cadherin by SNAI1 activation.
CONCLUSION
These findings suggested that PHF8 played an oncogenic role in facilitating FIP200-dependent autophagic degradation of E-cadherin, EMT and metastasis in HCC. PHF8 might be a promising target for prevention, treatment and prognostic prediction of HCC.
背景
植物同源域指蛋白 8（PHF8）作为上皮间质转化（EMT）的激活物，参与多种肿瘤的发生。然而，PHF8 在肝细胞癌（HCC）中的作用及其对 E-钙黏蛋白表达的调控作用尚不清楚。
方法
通过生物信息学分析研究 PHF8 的表达模式，并通过 RT-qPCR 和免疫组化在 HCC 组织和细胞系中验证。CCK8、异种移植肿瘤模型、Transwell 测定、串联 mCherry-GFP-LC3 融合蛋白测定用于评估 PHF8 对 HCC 细胞体外和体内增殖、转移和自噬的影响。ChIP、免疫印迹分析、挽救实验和抑制剂处理用于阐明 PHF8 促进 EMT、转移和自噬的机制。
结果
PHF8 的上调在 HCC 组织中非常普遍，与总生存期和无病复发生存期的恶化密切相关。此外，PHF8 敲低显著抑制细胞生长、迁移、侵袭和自噬，增加 E-钙黏蛋白水平，而 PHF8 过表达则导致相反的结果。此外，FIP200 的增加逆转了 PHF8 沉默对肿瘤迁移、侵袭和自噬的抑制作用。机制上，PHF8 参与转录调控 SNAI1、VIM 和 FIP200 的表达，而不是 N-钙黏蛋白和 E-钙黏蛋白。值得注意的是，PHF8 介导的 FIP200 依赖性自噬可以加速 E-钙黏蛋白的降解，这是 SNAI1 激活对 E-钙黏蛋白转录抑制的重要补充途径。
结论
这些发现表明，PHF8 在促进 HCC 中 FIP200 依赖性自噬降解、EMT 和转移中发挥致癌作用。PHF8 可能是 HCC 预防、治疗和预后预测的有前途的靶点。
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