Background Casticin, an isoflavone compound extracted from the herb Fructus Viticis, has demonstrated anti-inflammatory and anticancer activities and properties. The aim of this study was to investigate the effects and mechanisms of casticin in nasopharyngeal carcinoma (NPC) cells and to determine its potential for targeted use as a medicine. Methods NPC cells were used to perform the experiments. The CCK‑8 assay and colony formation assays were used to assess cell viability. Flow cytometry was used to measure the cell cycle and apoptosis analysis (annexin V/PI assay). A three-dimensional (3D) tumour sphere culture system was used to characterize the effect of casticin on NPC stem cells. In silico molecular docking prediction and high-throughput KINOME scan assays were used to evaluate the binding of casticin to phosphoinositide 3-kinase (PI3K), including wild-type and most of mutants variants. We also used the SelectScreen assay to detect the IC50 of ATP activity in the active site of the target kinase. Western blotting was used to evaluate the changes in key proteins involved cell cycle, apoptosis, stemness, and PI3K/protein kinase B (AKT) signalling. The effect of casticin treatment in vivo was determined by using a xenograft mouse model. Results Our results indicate that casticin is a new and novel selective PI3K inhibitor that can significantly inhibit NPC proliferation and that it induces G2/GM arrest and apoptosis by upregulating Bax/BCL2 expression. Moreover, casticin was observed to affect the self-renewal ability of the nasopharyngeal carcinoma cell lines, and a combination of casticin with BYL719 was observed to induce a decrease in the level of the phosphorylation of mTORC1 downstream targets in BYL719-insensitive NPC cell lines. Conclusion Casticin is a newly emerging selective PI3K inhibitor with potential for use as a targeted therapeutic treatment for nasopharyngeal carcinoma. Accordingly, casticin might represent a novel and effective agent against NPC and likely has high potential for combined use with pharmacological agents targeting PI3K/AKT.

中文翻译：

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Casticin 通过靶向磷酸肌醇 3-激酶来抑制鼻咽癌的生长。

背景 Casticin 是一种从草本植物葡萄中提取的异黄酮化合物，具有抗炎和抗癌活性和特性。本研究的目的是研究蓖麻毒素在鼻咽癌 (NPC) 细胞中的作用和机制，并确定其作为药物靶向使用的潜力。方法使用NPC细胞进行实验。CCK-8 测定和集落形成测定用于评估细胞活力。流式细胞仪用于测量细胞周期和细胞凋亡分析（膜联蛋白 V/PI 测定）。使用三维 (3D) 肿瘤球培养系统来表征蓖麻毒素对 NPC 干细胞的影响。计算机分子对接预测和高通量 KINOME 扫描测定用于评估蓖麻毒素与磷酸肌醇 3-激酶 (PI3K) 的结合，包括野生型和大多数突变体变体。我们还使用 SelectScreen 检测来检测靶激酶活性位点中 ATP 活性的 IC50。Western印迹用于评估涉及细胞周期、细胞凋亡、干性和PI3K/蛋白激酶B (AKT)信号传导的关键蛋白的变化。通过使用异种移植小鼠模型确定体内蓖麻毒素治疗的效果。结果 我们的结果表明，casticin 是一种新型的选择性 PI3K 抑制剂，可显着抑制 NPC 增殖，并通过上调 Bax/BCL2 表达诱导 G2/GM 停滞和细胞凋亡。此外，观察到蓖麻毒素影响鼻咽癌细胞系的自我更新能力，并且观察到蓖麻毒素与 BYL719 的组合可诱导 BYL719 不敏感的 NPC 细胞系中 mTORC1 下游靶标的磷酸化水平降低。结论 Casticin是一种新兴的选择性PI3K抑制剂，具有靶向治疗鼻咽癌的潜力。因此，casticin 可能代表一种新型有效的抗 NPC 药物，并可能与靶向 PI3K/AKT 的药物联合使用具有很高的潜力。