CircRNA inhibits DNA damage repair by interacting with host gene
CircRNA inhibits DNA damage repair by interacting with host gene
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CircRNA通过与宿主基因相互作用抑制DNA损伤修复
DOI：
10.1186/s12943-020-01246-x
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发表时间：
2020-08-24
期刊：
影响因子：
37.3
通讯作者：
Wei, Lei
中科院分区：
文献类型：
--
作者：
Xu, Xiaolong;Zhang, Jingwei;Wei, Lei
背景 失调的环状 RNA (circRNA) 与癌症的发展和治疗耐药性相关。然而，circRNA的功能研究主要集中在潜在的miRNA或蛋白质结合上，并且circRNA对癌症宿主基因DNA的更多潜在调控还有待检验。方法 我们对临床乳腺癌样本进行总RNA测序，鉴定患者血液、肿瘤和邻近正常组织中circRNA和相应宿主基因的表达模式。 qPCR、Northern blot 和原位杂交用于验证 circRNA circSMARCA5 的失调。通过R环斑点印迹、DNA-RNA免疫沉淀和质谱等一系列方法探讨circSMARCA5对外显子15转录的调控作用。此外，还进行了免疫荧光和体内实验来研究circSMARCA5的过度表达与药物敏感性。结果我们发现，在外周血中，circRNA 的表达量平均高于其宿主线性基因。与邻近正常组织相比，乳腺癌组织中的circSMARCA5降低，这与宿主基因SMARCA5相反。 circSMARCA5 的强制表达在体外和体内诱导乳腺癌细胞系的药物敏感性。此外，我们证明 circSMARCA5 可以与其亲本基因位点结合，形成 R 环，从而导致 SMARCA5 外显子 15 处的转录暂停。 CircSMARCA5 表达导致 SMARCA5 下调并产生截短的无功能蛋白，而 circSMARCA5 过表达足以提高对细胞毒性药物的敏感性。结论我们的研究结果揭示了circRNA对其宿主基因的新调控机制，并为circSMARCA5可能作为耐药乳腺癌患者的治疗靶点提供了证据。
Background Deregulated circular RNAs (circRNAs) are associated with the development of cancer and therapy resistance. However, functional research of circRNAs mostly focus on potential miRNA or protein binding and more potential regulation of circRNA on host gene DNA in cancers are yet to be inspected. Method We performed total RNA sequencing on clinical breast cancer samples and identified the expression patterns of circRNAs and corresponding host genes in patient blood, tumor and adjacent normal tissues. qPCR, northern blot and in situ hybridization were used to validate the dysregulation of circRNA circSMARCA5. A series of procedures including R-loop dot-blotting, DNA-RNA immunoprecipitation and mass spectrum, etc. were conducted to explore the regulation of circSMARCA5 on the transcription of exon 15 of SMARCA5. Moreover, immunofluorescence and in vivo experiments were executed to investigate the overexpression of circSMARCA5 with drug sensitivities. Results We found that circRNAs has average higher expression over its host linear genes in peripheral blood. Compared to adjacent normal tissues, circSMARCA5 is decreased in breast cancer tissues, contrary to host gene SMARCA5. The enforced expression of circSMARCA5 induced drug sensitivity of breast cancer cell lines in vitro and in vivo. Furthermore, we demonstrated that circSMARCA5 can bind to its parent gene locus, forming an R-loop, which results in transcriptional pausing at exon 15 of SMARCA5. CircSMARCA5 expression resulted in the downregulation of SMARCA5 and the production of a truncated nonfunctional protein, and the overexpression of circSMARCA5 was sufficient to improve sensitivity to cytotoxic drugs. Conclusion Our results revealed a new regulatory mechanism for circRNA on its host gene and provided evidence that circSMARCA5 may serve as a therapeutic target for drug-resistant breast cancer patients.