Wu Xiu-Xian, Kakehi Yoshiyuki, Jin Xing-Hua, Inui Masashi, Sugimoto Mikio
Department of Urology, Kagawa University Faculty of Medicine, Kagawa, Japan.
Urology. 2009 Jan;73(1):193-9. doi: 10.1016/j.urology.2008.04.055. Epub 2008 Aug 9.
Renal cell carcinoma (RCC) is one of the most drug-resistant malignancies, and an effective therapy is lacking for metastatic RCC. Vitamin E (VE) has been intensively studied as a chemopreventive agent for various cancer types. Preclinical investigations have suggested that VE succinate (VES) is the most effective analog of VE in cancer cells; however, no study of VES in RCC has been done. We investigated the anticancer activity of VES against RCC.
Cytotoxicity was assessed using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. Cell morphologic changes and cell viability were evaluated using phase-contrast microscopy and the trypan blue dye-exclusion test, respectively. Caspase activity was measured with a quantitative colorimetric assay.
VES exerted dose- and time-dependent cytotoxicities against ACHN, a human RCC cell line, but VE and VE acetate did not. The cytotoxic effect was also observed in 2 other RCC cell lines, Caki-1 and Caki-2, and in primary RCC cells derived from 8 patients. Hoechst 33258 staining and DNA ladder analysis demonstrated that VES induced apoptosis in RCC cells. However, VES did not affect activation of caspase-3, -6, -8, or -9. Furthermore, inhibitors specific to caspase-8, -9, -6, and -3 did not block VES cytotoxicity and neither did the general caspase inhibitor VAD.
VES might induce apoptosis and cytotoxicity against RCC cells in a caspase-independent manner and has potential in vivo applications in the treatment of drug-and/or immunotherapy-resistant RCC.
肾细胞癌（RCC）是最具耐药性的恶性肿瘤之一，目前缺乏针对转移性肾细胞癌的有效治疗方法。维生素E（VE）作为一种对多种癌症类型的化学预防剂已得到深入研究。临床前研究表明，维生素E琥珀酸酯（VES）是维生素E在癌细胞中最有效的类似物；然而，尚未有关于VES在肾细胞癌中的研究报道。我们研究了VES对肾细胞癌的抗癌活性。
采用3-（4,5-二甲基噻唑-2-基）-2,5-二苯基四氮唑溴盐法评估细胞毒性。分别使用相差显微镜和台盼蓝染料排除试验评估细胞形态变化和细胞活力。用定量比色法测定半胱天冬酶活性。
VES对人肾癌细胞系ACHN具有剂量和时间依赖性细胞毒性，但VE和维生素E醋酸酯则没有。在另外两种肾癌细胞系Caki-1和Caki-2以及来自8名患者的原发性肾癌细胞中也观察到了细胞毒性作用。Hoechst 33258染色和DNA梯状分析表明，VES诱导肾癌细胞凋亡。然而，VES并不影响半胱天冬酶-3、-6、-8或-9的激活。此外，半胱天冬酶-8、-9、-6和-3的特异性抑制剂均未阻断VES的细胞毒性，通用的半胱天冬酶抑制剂VAD也未阻断。
VES可能以不依赖半胱天冬酶的方式诱导肾癌细胞凋亡和细胞毒性，在体内治疗对药物和/或免疫治疗耐药的肾细胞癌方面具有潜在应用价值。
