The Histone Demethylase RBP2 Is Overexpressed in Gastric Cancer and Its Inhibition Triggers Senescence of Cancer Cells
The Histone Demethylase RBP2 Is Overexpressed in Gastric Cancer and Its Inhibition Triggers Senescence of Cancer Cells
复制标题
组蛋白去甲基化酶 RBP2 在胃癌中过度表达，其抑制会引发癌细胞衰老
DOI：
10.1053/j.gastro.2009.10.004
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发表时间：
2010-03-01
期刊：
影响因子：
29.4
通讯作者：
Xu, Dawei
中科院分区：
文献类型：
--
作者：
Zeng, Jiping;Ge, Zheng;Xu, Dawei
背景与目的：组蛋白修饰酶如组蛋白去乙酰化酶的异常表达与肿瘤发生有关。目前还不清楚RBP 2，一种新发现的组蛋白去甲基化酶，是否参与癌症的发展/进展。本研究检测了胃癌组织中RBP 2的表达及其在胃癌细胞中的生物学功能。方法：采用实时定量聚合酶链反应和免疫组织化学方法对42例胃癌患者的癌组织和配对的正常胃组织标本进行RBP 2表达分析。使用定量实时聚合酶链反应和免疫印迹法评估基因表达，并用小干扰RNA消除。通过病灶形成和β-半乳糖苷酶染色检查克隆形成和细胞衰老。启动子活性通过荧光素酶报告基因测定来确定。染色质免疫沉淀用于检测启动子上的RBP 2和甲基化组蛋白H3-K4。结果：胃癌组织中RBP 2 mRNA和蛋白表达分别为71.5%（30/42）和100%（20/20）。在RBP 2缺失的胃癌和宫颈癌细胞中，病灶数量显著减少，伴大量衰老/生长停滞和细胞周期蛋白依赖性激酶抑制剂（CDKIs）p21（CIP 1）、p27（kip 1）和/或p16（ink 4a）表达升高。通过抑制p21（CIP 1）或p27（kip 1）表达，可减弱RBP 2耗竭介导的衰老和克隆缺陷。RBP 2抑制增强了所有3个CDKI基因的启动子活性。在对照细胞中，RBP 2占据这些启动子，并且RBP 2占据的丧失伴随着RBP 2耗尽后增强的H3-K4三甲基化。结论：RBP 2在胃癌中过表达，并且其抑制至少部分地通过去抑制其靶基因CDKIs来触发恶性细胞的衰老。通过靶向RBP 2抑制组蛋白去甲基化酶可能是一种抗癌策略。
BACKGROUND & AIMS: The aberrant expression of histone-modifying enzymes such as histone deacetylases contributes to oncogenesis. It is unclear whether RBP2, a newly identified histone demethylase, is involved in cancer development/progression. We determined RBP2 expression in gastric cancer and its biologic function in cancer cells. METHODS: Cancerous and matched normal gastric specimens from 42 patients with gastric cancer were analyzed for RBP2 expression using quantitative real-time polymerase chain reaction and immunohistochemistry. Gene expression was assessed using quantitative real-time polymerase chain reaction and immunoblotting and depleted with small interference RNA. Clonogenesis and cellular senescence were examined by foci formation and beta-Galactosidase staining. Promoter activity was determined by luciferase reporter assay. Chromatin immunoprecipitation was used to detect RBP2 and methylated histone H3-K4 on promoters. RESULTS: RBP2 messenger RNA and protein expression were increased in 71.5% (30/42) and 100% (20/20) of gastric cancer specimens, respectively. Significantly diminished foci numbers coupled with massive senescence/growth arrest and elevated expression of cyclin-dependent kinase inhibitors (CDKIs) p21(CIP1), p27(kip1), and/or p16(ink4a) occurred in RBP2-depleted gastric and cervical cancer cells. RBP2 depletion-mediated senescence and clonogenic defect were attenuated by inhibiting p21(CIP1) or p27(kip1) expression. The promoter activity of all 3 CDKIs genes was enhanced by RBP2 inhibition. RBP2 occupied these promoters in control cells, and the loss of RBP2 occupancy was accompanied by enhanced H3-K4 trimethylation following RBP2 depletion. CONCLUSIONS: RBP2 is overexpressed in gastric cancer, and its inhibition triggers senescence of malignant cells at least partially by derepressing its target genes CDKIs. Histone demethylase inhibition by targeting RBP2 may be an anticancer strategy.