Circular RNA hsa_circ_0004872 inhibits gastric cancer progression via the miR-224/Smad4/ADAR1 successive regulatory circuit.
Circular RNA hsa_circ_0004872 inhibits gastric cancer progression via the miR-224/Smad4/ADAR1 successive regulatory circuit.
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环状RNA hsa_circ_0004872通过miR-224/Smad4/ADAR1连续调节电路抑制胃癌进展
DOI：
10.1186/s12943-020-01268-5
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发表时间：
2020-11-10
期刊：
影响因子：
37.3
通讯作者：
Liu Z
中科院分区：
文献类型：
--
作者：
Ma C;Wang X;Yang F;Zang Y;Liu J;Wang X;Xu X;Li W;Jia J;Liu Z
越来越多的证据表明，环状RNA（circRNA）在癌症的发生和发展中发挥着关键的调控作用。探究circRNA在肿瘤发生和进展中的作用及机制，可能有助于识别新的诊断标志物和治疗靶点。在本研究中，我们对hsa_circ_0004872在胃癌（GC）中的作用及调控机制进行了研究。
采用qRT - PCR检测hsa_circ_0004872在胃癌组织和细胞中的表达。分别运用EdU实验、CCK - 8实验、Transwell实验和划痕愈合实验评估hsa_circ_0004872对胃癌细胞增殖、侵袭和迁移的作用。通过裸鼠皮下和尾静脉注射肿瘤细胞的方式，评估hsa_circ_0004872在体内的作用。进行RNA免疫沉淀（RIP）实验、生物素偶联探针下拉实验、荧光原位杂交（FISH）及荧光素酶报告基因实验，以证实hsa_circ_0004872与已鉴定的微小RNA（miRNA）之间的关系。采用染色质免疫沉淀（ChIP）实验、荧光素酶报告基因实验和蛋白质免疫印迹（Western blot）实验，确定Smad4与ADAR1基因启动子的直接结合情况。
在本研究中，我们发现与癌旁非癌组织相比，hsa_circ_0004872在胃癌组织中显著下调。hsa_circ_0004872的表达水平与肿瘤大小和局部淋巴结转移相关。过表达hsa_circ_0004872可抑制胃癌细胞的增殖、侵袭和迁移，而敲低hsa_circ_0004872则产生相反的效果。裸鼠实验表明，异位表达hsa_circ_0004872在体内显著抑制肿瘤生长和转移。此外，我们证明hsa_circ_0004872作为miR - 224的“分子海绵”，上调miR - 224下游靶点p21和Smad4的表达。重要的是，我们发现RNA编辑酶ADAR1抑制hsa_circ_0004872的表达，并进一步导致miR - 224上调。miR - 224的下游靶点Smad4可通过直接结合ADAR1的启动子区域抑制ADAR1表达，进而影响hsa_circ_0004872的水平。
我们的研究结果表明，hsa_circ_0004872通过形成由hsa_circ_0004872/miR - 224/Smad4/ADAR1组成的负调控环，在胃癌中发挥抑癌作用。因此，hsa_circ_0004872可能成为胃癌潜在的生物标志物和治疗靶点。
补充信息见本文链接10.1186/s12943 - 020 - 01268 - 5 。
BackgroundEmerging evidence has shown that circular RNAs (circRNAs) play a crucial regulatory role in the occurrence and development of cancer. Exploring the roles and mechanisms of circRNAs in tumorigenesis and progression may help to identify new diagnostic markers and therapeutic targets. In the present study, we investigated the role and regulatory mechanism of hsa_circ_0004872 in gastric cancer (GC).MethodsqRT-PCR was used to determine the expression of hsa_circ_0004872 in GC tissues and cells. EdU, CCK-8, transwell and scratch wound healing assays were used to assess the role of hsa_circ_0004872 in GC cell proliferation, invasion and migration, respectively. Subcutaneous and tail vein tumor injections in nude mice were used to assess the role of hsa_circ_0004872 in vivo. RIP assay, biotin-coupled probe pull-down assay, FISH and luciferase reporter assay were performed to confirm the relationship between hsa_circ_0004872 and the identified miRNA. ChIP assay, luciferase reporter assay and western blot were used to determine the direct binding of Smad4 to the promoter of the ADAR1 gene.ResultsIn this study, we found that hsa_circ_0004872 was dramatically downregulated in GC tissues compared with adjacent noncancerous tissues. The expression level of hsa_circ_0004872 was associated with tumor size and local lymph node metastasis. Enforced expression of hsa_circ_0004872 inhibited the proliferation, invasion and migration of GC cells, whereas knockdown of hsa_circ_0004872 had the opposite effects. Nude mice experiments showed that ectopic expression of hsa_circ_0004872 dramatically inhibited tumor growth and metastasis in vivo. Moreover, we demonstrated that hsa_circ_0004872 acted as a “molecular sponge” for miR-224 to upregulate the expression of the miR-224 downstream targets p21 and Smad4. Importantly, we found that the RNA-editing enzyme ADAR1 inhibited hsa_circ_0004872 expression and further led to the upregulation of miR-224. Smad4, the downstream target of miR-224, could further affect hsa_circ_0004872 levels by directly binding to the promoter region of ADAR1 to inhibit ADAR1 expression.ConclusionsOur findings showed that hsa_circ_0004872 acted as a tumor suppressor in GC by forming a negative regulatory loop consisting of hsa_circ_0004872/miR-224/Smad4/ADAR1. Thus, hsa_circ_0004872 may serve as a potential biomarker and therapeutic target for GC.
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影响因子：
14.9
作者：
Hong H;An O;Chan THM;Ng VHE;Kwok HS;Lin JS;Qi L;Han J;Tay DJT;Tang SJ;Yang H;Song Y;Bellido Molias F;Tenen DG;Chen L
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