Demethylase-independent function of JMJD2D as a novel antagonist of p53 to promote Liver Cancer initiation and progression
Demethylase-independent function of JMJD2D as a novel antagonist of p53 to promote Liver Cancer initiation and progression
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JMJD2D 作为 p53 新型拮抗剂的去甲基化酶独立功能促进肝癌的发生和进展
DOI：
10.7150/thno.45581
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发表时间：
2020-01-01
期刊：
影响因子：
12.4
通讯作者：
Li, Wengang
中科院分区：
文献类型：
--
作者：
Li, Ming;Deng, Yuan;Li, Wengang
背景：JMJD2D作为一种组蛋白去甲基酶，可以通过特异性地去甲基化H3K9me2/3而增强基因表达，在促进结直肠癌进展中发挥重要作用。然而，它在肝癌中的作用尚不清楚。方法：采用免疫组织化学和免疫印迹法检测JMJD2D在人肝癌组织和非肿瘤肝组织中的表达。利用小发夹RNA下调JMJD2D在肝癌细胞中的表达，并通过Western印迹、实时荧光定量PCR、细胞存活率、克隆形成和流式细胞术分析细胞。裸鼠移植瘤生长，免疫组织化学方法检测肿瘤细胞增殖和凋亡情况。采用免疫共沉淀法、染色质免疫共沉淀法和电子迁移率改变法研究JMJD2D与P53的关系。给野生型和JMJD2D基因敲除小鼠腹腔注射二乙基亚硝胺(DEN)诱发肝癌，观察肝癌的发生发展。结果：与非肿瘤肝组织相比，JMJD2D在人肝癌组织中表达明显上调。JMJD2D高表达的肝癌患者总体生存率明显低于JMJD2D低表达的肝癌患者。JMJD2D基因敲除降低了肝癌细胞的增殖和移植瘤的生长，使细胞对化疗药物诱导的凋亡敏感，并增加了细胞周期抑制因子p21和促凋亡基因PUMA的表达。在遗传学上，JMJD2D缺陷保护小鼠免受DEN诱导的肝癌的发生和发展。抑癌基因P53的敲除显著降低了JMJD2D对细胞增殖、凋亡以及p21和PUMA表达的影响，提示JMJD2D部分通过抑制P53信号通路来调节肝癌细胞的功能。在机制上，JMJD2D直接与P53相互作用，以一种去甲基化活性非依赖的方式抑制P53向p21和PUMA启动子的募集，暗示JMJD2D作为一种新的P53拮抗剂具有去甲基酶非依赖性功能。此外，JMJD2D还可激活Wnt/β-catenin信号通路，促进肝癌细胞增殖。结论：JMJD2D可以拮抗抑癌基因P53，同时激活一条致癌信号通路(如Wnt/β-Catenin信号通路)，从而促进肝癌的发生和发展，提示JMJD2D可能成为肝癌治疗的新靶点。
Background: As a histone demethylase, JMJD2D can enhance gene expression by specifically demethylating H3K9me2/3 and plays an important role in promoting colorectal cancer progression. However, its role in liver cancer remains unclear. Methods: The expression of JMJD2D was examined in human liver cancer specimens and non-tumorous liver tissues by immunohistochemical or immunoblot analysis. JMJD2D expression was knocked down in liver cancer cells using small hairpin RNAs, and cells were analyzed with Western blot, real-time PCR, cell viability, colony formation, and flow cytometry assays. Cells were also grown as tumor xenografts in nude mice, and the tumor cell proliferation and apoptosis were measured by immunohistochemical analysis. The relationship between JMJD2D and p53 was studied by co-immunoprecipitation, chromatin immunoprecipitation, and electric mobility shift assay. Wild-type and JMJD2D-knockout mice were intraperitoneally injected with diethylnitrosamine (DEN) to induce liver tumors and the liver cancer initiation and progression were investigated. Results: JMJD2D was frequently upregulated in human liver cancer specimens compared with non-tumorous liver tissues. The overall survival of liver cancer patients with high JMJD2D expression was significantly decreased compared to that with low JMJD2D expression. JMJD2D knockdown reduced liver cancer cell proliferation and xenograft tumor growth, sensitized cells to chemotherapeutic drug-induced apoptosis, and increased the expression of cell cycle inhibitor p21 and pro-apoptosis gene PUMA. Genetically, JMJD2D deficiency protected mice against DEN-induced liver cancer initiation and progression. Knockout of tumor suppressor p53 significantly reduced the effects of JMJD2D knockdown on cell proliferation, apoptosis, and the expression of p21 and PUMA, suggesting that JMJD2D regulates liver cancer cell functions in part through inhibiting p53 signaling pathway. Mechanistically, JMJD2D directly interacted with p53 and inhibited p53 recruitment to the p21 and PUMA promoters in a demethylation activity-independent manner, implicating a demethylase-independent function of JMJD2D as a novel p53 antagonist. In addition, JMJD2D could activate Wnt/β-catenin signaling to promote liver cancer cell proliferation. Conclusion: Our study demonstrates that JMJD2D can antagonize the tumor suppressor p53 and activate an oncogenic signaling pathway (such as Wnt/β-catenin signaling pathway) simultaneously to promote liver cancer initiation and progression, suggesting that JMJD2D may serve as a novel target for liver cancer treatment.