Liu Jian, Li Kai, Wang Rui, Chen Sisi, Wu Jie, Li Xiang, Ning Qian, Yang Ganghua, Pang Yamei
Department of Respiratory and Critical Care Medicine, the First Affiliated Hospital of Xi'an Jiaotong University, 277 Yanta West Road, Xian, 710061, Shaanxi, China.
Department of Thoracic Surgery, the First Affiliated Hospital of Xi'an Jiaotong University, Xi'an, 710061, Shaanxi, China.
Cancer Cell Int. 2020 Dec 9;20(1):594. doi: 10.1186/s12935-020-01697-8.
Activating transcription factor 2 (ATF2), a member of the activator protein 1 (AP-1) transcription factor family, has been shown to be involved in the pathobiology of numerous cancers. However, the biological role and mechanism of ATF2 in lung adenocarcinoma (LUAD) remains to be elucidated.
The expression of ATF2, NEAT1 and miR-26a-5p in LUAD tissues and cell lines was detected by qRT-PCR and western blotting. The interaction between ATF2, NEAT1, and miR-26a-5p was validated by chromatin immunoprecipitation, luciferase reporter assay and RNA immunoprecipitation. Cell proliferation, invasion and tumorigenesis of LUAD cells were analyzed by using CCK8, transwell invasion assay and xenograft tumor model.
We confirmed that ATF2 expression was increased in LUAD tissues compared with normal adjacent lung tissues. Functional experiments showed that ATF2 positively regulated cell proliferation and invasion in LUAD cells. Moreover, we identified that NEAT1 expression was increased in LUAD tissues and positively correlated with ATF2 expression. Mechanistically, ATF2 could bind to the promoter of NEAT1 to promote its transcription. Rescue experiments showed that ATF2 exerted its oncogenic function in LUAD, at least, partly through NEAT1 upregulation. In turn, NEAT1 could positively regulate ATF2 expression and form a positive feedback loop in LUAD cells. Furthermore, we demonstrated that NEAT1 positively regulated ATF2 expression via sponging miR-26a-5p.
ATF2 and NEAT1 form a positive feedback loop mediated by miR-26a-5p and coordinately contribute to LUAD progression.
激活转录因子2（ATF2）是激活蛋白1（AP-1）转录因子家族的成员，已被证明参与多种癌症的病理生物学过程。然而，ATF2在肺腺癌（LUAD）中的生物学作用和机制仍有待阐明。
采用qRT-PCR和蛋白质免疫印迹法检测LUAD组织和细胞系中ATF2、NEAT1和miR-26a-5p的表达。通过染色质免疫沉淀、荧光素酶报告基因检测和RNA免疫沉淀验证ATF2、NEAT1和miR-26a-5p之间的相互作用。使用CCK8、Transwell侵袭实验和异种移植肿瘤模型分析LUAD细胞的增殖、侵袭和肿瘤发生情况。
我们证实，与相邻正常肺组织相比，LUAD组织中ATF2表达增加。功能实验表明，ATF2正向调节LUAD细胞的增殖和侵袭。此外，我们发现LUAD组织中NEAT1表达增加，且与ATF2表达呈正相关。机制上，ATF2可与NEAT1启动子结合以促进其转录。挽救实验表明，ATF2在LUAD中发挥致癌作用，至少部分是通过上调NEAT1实现的。反过来，NEAT1可正向调节ATF2表达，并在LUAD细胞中形成正反馈回路。此外，我们证明NEAT1通过海绵吸附miR-26a-5p正向调节ATF2表达。
ATF2和NEAT1形成由miR-26a-5p介导的正反馈回路，并协同促进LUAD进展。
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