UKM Medical Molecular Biology Institute (UMBI), UKM Medical Center, Jalan Ya'acob, Bandar Tun Razak, Cheras, Kuala Lumpur 56000, Malaysia.
BMC Complement Altern Med. 2014 Jul 1;14:213. doi: 10.1186/1472-6882-14-213.
Gamma-tocotrienol (GTT), an isomer of vitamin E and hydroxy-chavicol (HC), a major bioactive compound in Piper betle, has been reported to possess anti-carcinogenic properties by modulating different cellular signaling events. One possible strategy to overcome multi-drug resistance and high toxic doses of treatment is by applying combinational therapy especially using natural bioactives in cancer treatment.
In this study, we investigated the interaction of GTT and HC and its mode of cell death on glioma cell lines. GTT or HC alone and in combination were tested for cytotoxicity on glioma cell lines 1321N1 (Grade II), SW1783 (Grade III) and LN18 (Grade IV) by [3-(4,5-dimethylthiazol-2- yl)-5-(3-carboxymethoxy-phenyl)-2-(4-sulfophenyl)- 2H- tetrazolium, inner salt] MTS assay. The interactions of each combination were evaluated by using the combination index (CI) obtained from an isobologram.
Individually, GTT or HC displayed mild growth inhibitory effects against glioma cancer cell lines at concentration values ranging from 42-100 μg/ml and 75-119 μg/ml respectively. However, the combination of sub-lethal doses of GTT + HC dramatically enhanced the inhibition of glioma cancer cell proliferation and exhibited a strong synergistic effect on 1321N1 with CI of 0.55, and CI = 0.54 for SW1783. While in LN18 cells, moderate synergistic interaction of GTT + HC was observed with CI value of 0.73. Exposure of grade II, III and IV cells to combined treatments for 24 hours led to increased apoptosis as determined by annexin-V FITC/PI staining and caspase-3 apoptosis assay, showing caspase-3 activation of 27%, 7.1% and 79% respectively.
In conclusion, combined treatments with sub-effective doses of GTT and HC resulted in synergistic inhibition of cell proliferation through the induction of apoptosis of human glioma cells in vitro.
γ-生育三烯酚（GTT）是维生素 E 的一种异构体，羟基查尔酮（HC）是菝葜中的一种主要生物活性化合物，据报道，通过调节不同的细胞信号事件，具有抗癌特性。克服多药耐药和高治疗毒性剂量的一种可能策略是应用联合治疗，特别是在癌症治疗中使用天然生物活性物质。
在这项研究中，我们研究了 GTT 和 HC 的相互作用及其对神经胶质瘤细胞系的细胞死亡方式。通过[3-（4,5-二甲基噻唑-2-基）-5-（3-羧甲氧基苯基）-2-（4-磺苯基）-2H-四唑，内盐] MTS 测定法，单独或联合使用 GTT 或 HC 测试其对神经胶质瘤细胞系 1321N1（II 级）、SW1783（III 级）和 LN18（IV 级）的细胞毒性。通过来自等对作图的组合指数（CI）评估每种组合的相互作用。
单独使用时，GTT 或 HC 分别在 42-100μg/ml 和 75-119μg/ml 的浓度范围内对神经胶质瘤癌细胞系显示出轻微的生长抑制作用。然而，亚致死剂量的 GTT+HC 的组合可显著增强神经胶质瘤癌细胞增殖的抑制作用，并对 1321N1 表现出强烈的协同作用，CI 为 0.55，SW1783 的 CI 为 0.54。在 LN18 细胞中，观察到 GTT+HC 的中度协同相互作用，CI 值为 0.73。用联合处理物处理 II 级、III 级和 IV 级细胞 24 小时后，通过 Annexin-V FITC/PI 染色和 caspase-3 凋亡测定法确定凋亡增加，显示 caspase-3 分别激活 27%、7.1%和 79%。
总之，用亚有效剂量的 GTT 和 HC 联合治疗可通过体外诱导人神经胶质瘤细胞凋亡，协同抑制细胞增殖。
