Purpose

Non-small cell lung cancer (NSCLC) is a leading cause of cancer-related mortality world-wide. Recently, a number of circular RNAs (circRNAs) has been found to be differentially expressed in human NSCLCs, correlating with clinico-pathological features. As yet, the expression and potential role of circRNA BIRC6 (circBIRC6) in NSCLC have not been studied.

Methods

Expression of circBIRC6 and its target microRNA-145 (miR-145) in human NSCLC cells and tissues was assessed using qRT-PCR. In vitro genetic strategies were used to exogenously alter circBIRC6 and miR-145 expression. Their impact on in vitro and in vivo NSCLC cell behavior was studied.

Results

We found that circBIRC6 was upregulated in primary human NSCLC tissues and NSCLC cells, whereas its potential target, miR-145, was downregulated. In A549 NSCLC cells and primary human NSCLC cells, shRNA-induced silencing of circBIRC6 potently inhibited their growth, proliferation, migration and invasion. Conversely, we found that exogenous overexpression of circBIRC6 promoted these characteristics. Using RNA immunoprecipitation (RIP) in A549 cells, we found that Argonaute 2 (Ago2) immunoprecipitated together with both circBIRC6 and miR-145. Additional studies revealed that the miR-145 level increased after circBIRC6 silencing in A549 cells, but decreased after circBIRC6 overexpression. Of note, we found that the circBIRC6 silencing-induced anti-A549 activity could be attenuated by a miR-145 inhibitor. Lastly, we found that circBIRC6 silencing inhibited the growth of NSCLC xenografts in severe combined immunodeficient mice.

Conclusions

From our data we conclude that circBIRC6 overexpression promotes NSCLC cell progression, possibly by sponging miR-145.

中文翻译：

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CircRNA BIRC6通过海绵化microRNA-145促进非小细胞肺癌细胞的进程。

目的

非小细胞肺癌（NSCLC）是全球范围内与癌症相关的死亡率的主要原因。最近，已经发现许多环状RNA（circRNA）在人NSCLC中差异表达，与临床病理特征相关。到目前为止，尚未研究circRNA BIRC6（circBIRC6）在NSCLC中的表达及其潜在作用。

方法

使用qRT-PCR评估circBIRC6及其靶标microRNA-145（miR-145）在人NSCLC细胞和组织中的表达。体外遗传策略用于外源性改变circBIRC6和miR-145表达。研究了它们对体外和体内NSCLC细胞行为的影响。

结果

我们发现circBIRC6在原代人NSCLC组织和NSCLC细胞中被上调，而其潜在靶标miR-145被下调。在A549 NSCLC细胞和原代人NSCLC细胞中，shRNA诱导的circBIRC6沉默可有效抑制其生长，增殖，迁移和侵袭。相反，我们发现circBIRC6的外源性过表达促进了这些特征。使用A549细胞中的RNA免疫沉淀（RIP），我们发现Argonaute 2（Ago2）与circBIRC6和miR-145一起免疫沉淀。进一步的研究表明，miR-145水平在A549细胞中circBIRC6沉默后升高，但在circBIRC6过表达后降低。值得注意的是，我们发现，miR-145抑制剂可减弱circBIRC6沉默诱导的抗A549活性。最后，

结论

根据我们的数据，我们得出结论，circBIRC6过表达可能通过使miR-145海绵化来促进NSCLC细胞的进程。