Background: Intratumoral heterogeneity is the primary challenge in the treatment of glioblastoma (GBM). The presence of glioma stem cells (GSCs) and their conversion between different molecular phenotypes contribute to the complexity of heterogeneity, culminating in preferential resistance to radiotherapy. ARP2/3 (actin-related protein-2/3) complexes (ARPs) are associated with cancer migration, invasion and differentiation, while the implications of ARPs in the phenotype and resistance to radiotherapy of GSCs remain unclear. Methods: We screened the expression of ARPs in TCGA-GBM and CGGA-GBM databases. Tumor sphere formation assays and limiting dilution assays were applied to assess the implications of ARPC1B in tumorigenesis. Apoptosis, comet, γ-H2AX immunofluorescence (IF), and cell cycle distribution assays were used to evaluate the effect of ARPC1B on radiotherapy resistance. Immunoprecipitation (IP) and mass spectrometry analysis were used to detect ARPC1B-interacting proteins. Immune blot assays were performed to evaluate protein ubiquitination, and deletion mutant constructs were designed to determine the binding sites of protein interactions. The Spearman correlation algorithm was performed to screen for drugs that indicated cell sensitivity by the expression of ARPC1B. An intracranial xenograft GSC mouse model was used to investigate the role of ARPC1B in vivo. Results: We concluded that ARPC1B was significantly upregulated in MES-GBM/GSCs and was correlated with a poor prognosis. Both in vitro and in vivo assays indicated that knockdown of ARPC1B in MES-GSCs reduced tumorigenicity and resistance to IR treatment, whereas overexpression of ARPC1B in PN-GSCs exhibited the opposite effects. Mechanistically, ARPC1B interacted with IFI16 and HuR to maintain protein stability. In detail, the Pyrin of IFI16 and RRM2 of HuR were implicated in binding to ARPC1B, which counteracted TRIM21-mediated degradation of ubiquitination to IFI16 and HuR. Additionally, the function of ARPC1B was dependent on IFI16-induced activation of NF-κB pathway and HuR-induced activation of STAT3 pathway. Finally, we screened AZD6738, an ataxia telangiectasia mutated and rad3-related (ATR) inhibitor, based on the expression of ARPC1B. In addition to ARPC1B expression reflecting cellular sensitivity to AZD6738, the combination of AZD6738 and radiotherapy exhibited potent antitumor effects both in vitro and in vivo. Conclusion: ARPC1B promoted MES phenotype maintenance and radiotherapy resistance by inhibiting TRIM21-mediated degradation of IFI16 and HuR, thereby activating the NF-κB and STAT3 signaling pathways, respectively. AZD6738, identified based on ARPC1B expression, exhibited excellent anti-GSC activity in combination with radiotherapy.Keywords: ARPC1B; AZD6738; Glioblastoma; Glioma stem cells; Radiotherapy resistance.

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乐备实（上海优宁维生物科技股份有限公司旗下全资子公司），是国内专注于提供高质量蛋白检测以及组学分析服务的实验服务专家，自2018年成立以来，乐备实不断寻求突破，公司的服务技术平台已扩展到单细胞测序、空间多组学、流式检测、超敏电化学发光、Luminex多因子检测、抗体芯片、PCR Array、ELISA、Elispot、PLA蛋白互作、多色免疫组化、DSP空间多组学等30多个，建立起了一套涵盖基因、蛋白、细胞以及组织水平实验的完整检测体系。

 
我们可提供从样本运输、储存管理、样本制备、样本检测到检测数据分析的全流程服务。凭借严格的实验室管理流程、标准化实验室操作、原始数据储存体系以及实验项目管理系统，已经为超过3000家客户单位提供服务，年检测样本超过100万，受到了广大客户的信任与支持。