hTERT promotes the invasion of gastric cancer cells by enhancing FOXO3a ubiquitination and subsequent ITGB1 upregulation
hTERT promotes the invasion of gastric cancer cells by enhancing FOXO3a ubiquitination and subsequent ITGB1 upregulation
复制标题
hTERT通过增强FOXO3a泛素化和随后的ITGB1上调促进胃癌细胞的侵袭
DOI：
10.1136/gutjnl-2015-309322
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发表时间：
2017-01-01
期刊：
影响因子：
24.5
通讯作者：
Yang, Shi-ming
中科院分区：
文献类型：
--
作者：
Hu, Changjiang;Ni, Zhenghong;Yang, Shi-ming
背景与目的人端粒酶逆转录酶（human telomerase reverse transcriptase，hTERT）在肿瘤侵袭中起重要作用，但其作用机制尚不清楚。本研究旨在探讨hTERT在胃癌转移中的作用及其机制。设计采用蛋白质组学分析、qPCR和western blotting技术筛选hTERT调控胃癌侵袭的候选分子。进行染色质免疫沉淀（ChIP）qPCR以鉴定整合素β1（ITGB 1）基因调控区的hTERT结合位点。进一步应用ChIP分析来阐明与调控区结合的转录因子。通过免疫共沉淀（Co-IP）和谷胱甘肽S-转移酶（GST）pull-down实验检测hTERT与转录因子之间的相互作用。此外，所揭示的途径在荷瘤裸鼠和人胃癌组织中得到验证。结果ITGB 1为hTERT的下游基因，该基因存在两个hTERT结合区。hTERT抑制了叉头盒O3（FOXO 3a）与FOXO 3a结合元件（+9972 <$+9978）的结合，但增强了叉头盒M1（FOXM 1）与ITGB 1基因中FOXM 1结合元件（-1104 <$-1109）的结合。重要的是，FOXO 3a在hTERT诱导的ITGB 1表达中起主要作用，hTERT/鼠双微体2（MDM 2）复合物促进了FOXO 3a的泛素介导的降解。人胃癌组织中hTERT表达水平与ITGB 1表达水平呈正相关。结论hTERT/MDM 2-FOXO 3a-ITGB 1通路在hTERT促进胃癌侵袭中起重要作用，提示该通路可能成为防治胃癌转移的新靶点。
Background and aims Human telomerase reverse transcriptase (hTERT) plays an important role in cancer invasion, but the relevant mechanism is not well known. This study aims to investigate the role and mechanism of hTERT in gastric cancer metastasis. Design Proteomics analysis, qPCR and western blotting were used to screen for hTERT-regulated candidate molecules in gastric cancer invasion. Chromatin immunoprecipitation (ChIP) qPCR was performed to identify the binding sites of hTERT at the regulatory region of the integrin β1 (ITGB1) gene. ChIP assays were further applied to elucidate the transcription factors that bound to the regulatory region. The interactions between hTERT and the transcription factors were tested by co-immunoprecipitation (Co-IP) and glutathione S-transferase (GST) pull-down experiments. Moreover, the revealed pathway was verified in tumour-bearing nude mice and human gastric cancer tissues. Results ITGB1 was identified as a downstream gene of hTERT, and there were two hTERT-binding regions within this gene. hTERT alleviated the binding of forkhead box O3 (FOXO3a) to FOXO3a binding element (+9972∼+9978), but it enhanced the binding of forkhead box M1 (FOXM1) to FOXM1 binding element (−1104∼−1109) in ITGB1 gene. Importantly, FOXO3a played a major role in hTERT-induced ITGB1 expression, and the hTERT/murine double minute 2 (MDM2) complex promoted the ubiquitin-mediated degradation of FOXO3a. Moreover, hTERT increased ITGB1 expression in xenograft gastric cancer, and the level of hTERT was positively correlated with that of ITGB1 in human gastric cancer tissues. Conclusions The hTERT/MDM2–FOXO3a–ITGB1 pathway markedly contributes to hTERT-promoted gastric cancer invasion, suggesting that this pathway might be a novel target for the prevention and treatment of gastric cancer metastasis.