Abstract Context: Cisplatin-based chemotherapy was widely used in treating human malignancies. However, side effects and chemoresistance remains the major obstacle. Objective: To verify whether natural borneol (NB) can enhance cisplatin-induced glioma cell apoptosis and explore the mechanism. Materials and methods: Cytotoxicity of cisplatin and/or NB towards U251 and U87 cells were determined with the MTT assay. Cells were treated with 0.25–80 μg/mL cisplatin and/or 5–80 μM NB for 48 h. The effects of NB and/or cisplatin on apoptosis and cell cycle distribution were quantified by flow cytometric analysis. Protein expression was detected by western blotting. ROS generation was conducted by measuring and visualising an oxidation-sensitive fluorescein DCFH-DA. Results: NB synergistically enhanced the anticancer efficacy of cisplatin in human glioma cells. Co-treatment of 40 μg/mL NB and 40 μg/mL cisplatin significantly inhibited U251 cell viability from 100% to 28.2% and increased the sub-G1 population from 1.4% to 59.3%. Further detection revealed that NB enhanced cisplatin-induced apoptosis by activating caspases and triggering reactive oxygen species (ROS) overproduction as evidenced by the enhancement of green fluorescence intensity from 265% to 645%. ROS-mediated DNA damage was observed as reflected by the activation of ATM/ATR, p53 and histone. Moreover, MAPKs and PI3K/AKT pathways also contributed to co-treatment-induced U251 cell growth inhibition. ROS inhibition by antioxidants effectively improved MAPKs and PI3K/AKT functions and cell viability, indicating that NB enhanced cisplatin-induced cell growth in a ROS-dependent manner. Discussion and conclusions: Natural borneol had the potential to sensitise human glioma cells to cisplatin-induced apoptosis with potential application in the clinic.

中文翻译：

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天然冰片通过触发 ROS 介导的氧化损伤和调节 MAPKs 和 PI3K/AKT 通路，使人神经胶质瘤细胞对顺铂诱导的细胞凋亡敏感

摘要 背景：以顺铂为基础的化疗广泛用于治疗人类恶性肿瘤。然而，副作用和化学抗性仍然是主要障碍。目的：验证天然冰片（NB）是否能促进顺铂诱导的胶质瘤细胞凋亡并探讨其机制。材料和方法： 顺铂和/或 NB 对 U251 和 U87 细胞的细胞毒性用 MTT 试验测定。细胞用 0.25-80 μg/mL 顺铂和/或 5-80 μMN NB 处理 48 小时。通过流式细胞术分析量化NB和/或顺铂对细胞凋亡和细胞周期分布的影响。通过蛋白质印迹检测蛋白质表达。通过测量和可视化氧化敏感荧光素 DCFH-DA 来产生 ROS。结果：NB协同增强顺铂在人神经胶质瘤细胞中的抗癌功效。40 μg/mL NB 和 40 μg/mL 顺铂的共同处理显着抑制了 U251 细胞活力，从 100% 到 28.2%，并将亚 G1 细胞群从 1.4% 增加到 59.3%。进一步检测表明，NB 通过激活半胱天冬酶和触发活性氧 (ROS) 过量产生来增强顺铂诱导的细胞凋亡，如绿色荧光强度从 265% 增强到 645% 所证明的那样。观察到 ROS 介导的 DNA 损伤，这反映在 ATM/ATR、p53 和组蛋白的激活上。此外，MAPKs 和 PI3K/AKT 通路也有助于共同治疗诱导的 U251 细胞生长抑制。抗氧化剂对 ROS 的抑制有效地改善了 MAPK 和 PI3K/AKT 功能和细胞活力，表明NB以ROS依赖性方式增强顺铂诱导的细胞生长。讨论和结论：天然冰片具有使人神经胶质瘤细胞对顺铂诱导的细胞凋亡敏感的潜力，具有临床应用潜力。