Abstract

Background

Acquired chemoresistance is a major challenge in the clinical treatment of glioblastoma (GBM). Circular RNAs have been verified to play a role in tumor chemoresistance. However, the underlying mechanisms remain unclear. The aim of this study was to elucidate the potential role and molecular mechanism of circular (circ)RNA ADP-ribosylation factor GTPase activating proteins with Src homology 3 domain, ankyrin repeat and Pleckstrin homology domain 1 (circASAP1) in temozolomide (TMZ) resistance of GBM.

Methods

We analyzed circRNA alterations in recurrent GBM tissues relative to primary GBM through RNA sequencing. Real-time quantitative reverse transcription PCR verified the expression of circASAP1 in tissues and cells. Knockdown and overexpressed plasmids were used to evaluate the effect of circASAP1 on GBM cell proliferation and TMZ-induced apoptosis. Mechanistically, fluorescent in situ hybridization, dual-luciferase reporter, and RNA immunoprecipitation assays were performed to confirm the regulatory network of circASAP1/miR-502-5p/neuroblastoma Ras (NRAS). An intracranial tumor model was used to verify our findings in vivo.

Results

CircASAP1 expression was significantly upregulated in recurrent GBM tissues and TMZ-resistant cell lines. CircASAP1 overexpression enhanced GBM cell proliferation and TMZ resistance, which could be reduced by circASAP1 knockdown. Further experiments revealed that circASAP1 increased the expression of NRAS via sponging miR-502-5p. Moreover, circASAP1 depletion effectively restored the sensitivity of TMZ-resistant xenografts to TMZ treatment in vivo.

Conclusions

Our data demonstrate that circASAP1 exerts regulatory functions in GBM and that competing endogenous (ce)RNA-mediated microRNA sequestration might be a potential therapeutic strategy for GBM treatment.

中文翻译：

---

EIF4A3诱导的环状RNA ASAP1通过NRAS/MEK1/ERK1-2信号传导促进胶质母细胞瘤的肿瘤发生和替莫唑胺耐药

摘要

背景

获得性化疗耐药是胶质母细胞瘤（GBM）临床治疗的主要挑战。环状RNA已被证实在肿瘤化疗耐药中发挥作用。然而，其根本机制仍不清楚。本研究的目的是阐明具有 Src 同源 3 结构域、锚蛋白重复序列​​和 Pleckstrin 同源结构域 1 (circASAP1) 的环状 (circ)RNA ADP-核糖基化因子 GTPase 激活蛋白在替莫唑胺 (TMZ) 耐药中的潜在作用和分子机制。 GBM。

方法

我们通过 RNA 测序分析了复发性 GBM 组织相对于原发性 GBM 的 circRNA 变化。实时定量逆转录PCR验证了circASAP1在组织和细胞中的表达。使用敲低和过表达质粒来评估 circASAP1 对 GBM 细胞增殖和 TMZ 诱导的细胞凋亡的影响。从机制上讲，进行荧光原位杂交、双荧光素酶报告基因和RNA免疫沉淀测定来确认circASAP1/miR-502-5p/神经母细胞瘤Ras (NRAS)的调控网络。使用颅内肿瘤模型来验证我们的体内发现。

结果

CircASAP1 表达在复发 GBM 组织和 TMZ 耐药细胞系中显着上调。CircASAP1 过度表达增强 GBM 细胞增殖和 TMZ 耐药性，而 circASAP1 敲低可降低这种增殖和 TMZ 耐药性。进一步的实验表明，circASAP1 通过海绵 miR-502-5p 增加 NRAS 的表达。此外，circASAP1耗竭有效恢复了TMZ耐药异种移植物对体内TMZ治疗的敏感性。

结论

我们的数据表明，circASAP1 在 GBM 中发挥调节功能，并且竞争性内源性 (ce)RNA 介导的 microRNA 隔离可能是 GBM 治疗的潜在治疗策略。