Resistance to the Translation Initiation Inhibitor Silvestrol is Mediated by ABCB1/P-Glycoprotein Overexpression in Acute Lymphoblastic Leukemia Cells
Resistance to the Translation Initiation Inhibitor Silvestrol is Mediated by ABCB1/P-Glycoprotein Overexpression in Acute Lymphoblastic Leukemia Cells
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DOI：
10.1208/s12248-011-9276-7
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发表时间：
2011-09-01
期刊：
影响因子：
4.5
通讯作者：
Lucas, David M.
中科院分区：
文献类型：
--
作者：
Gupta, Sneha V.;Sass, Ellen J.;Lucas, David M.
蛋白质合成在白血病和其他癌症中是一个重要的治疗靶点，但直接影响这一过程且在药理学上可行的药物很少。植物来源的药物silvestrol通过干扰eIF4A/mRNA与eIF4F的组装来特异性抑制翻译起始。Silvestrol在包括急性淋巴细胞白血病（ALL）在内的多种癌症模型中具有强大的体外和体内活性，并且正在由美国国家癌症研究所进行临床前开发，但关于耐药的潜在机制尚无相关信息。在另一项报告中，我们表明腹腔注射silvestrol在全身的生物利用度约为100%，尽管口服剂量的生物利用度仅为1%，尽管似乎没有代谢。为了探索silvestrol耐药机制以及外排转运蛋白在silvestrol处置中的可能作用，我们对通过在逐渐增加的silvestrol浓度下培养697 ALL细胞系而产生的一种对silvestrol耐药的ALL细胞系中的多药耐药转运蛋白的表达和功能进行了表征。这种耐药细胞系697 - R显示ABCB1 mRNA和P - 糖蛋白（Pgp）显著上调，并且对已知的Pgp底物长春新碱和罗米地辛具有交叉耐药性。此外，697 - R细胞容易外排荧光Pgp底物罗丹明123。这种作用可被Pgp抑制剂维拉帕米和环孢菌素A以及针对ABCB1的siRNA所阻止，同时对silvestrol重新敏感。总之，这些数据表明silvestrol是Pgp的底物，这是在开发用于口服给药或针对由Pgp过表达保护的肿瘤的silvestrol时必须考虑的一个潜在障碍。
Protein synthesis is a powerful therapeutic target in leukemias and other cancers, but few pharmacologically viable agents are available that affect this process directly. The plant-derived agent silvestrol specifically inhibits translation initiation by interfering with eIF4A/mRNA assembly with eIF4F. Silvestrol has potent in vitro and in vivo activity in multiple cancer models including acute lymphoblastic leukemia (ALL) and is under pre-clinical development by the US National Cancer Institute, but no information is available about potential mechanisms of resistance. In a separate report, we showed that intraperitoneal silvestrol is approximately 100% bioavailable systemically, although oral doses were only 1% bioavailable despite an apparent lack of metabolism. To explore mechanisms of silvestrol resistance and the possible role of efflux transporters in silvestrol disposition, we characterized multi-drug resistance transporter expression and function in a silvestrol-resistant ALL cell line generated via culture of the 697 ALL cell line in gradually increasing silvestrol concentrations. This resistant cell line, 697-R, shows significant upregulation of ABCB1 mRNA and P-glycoprotein (Pgp) as well as cross-resistance to known Pgp substrates vincristine and romidepsin. Furthermore, 697-R cells readily efflux the fluorescent Pgp substrate rhodamine 123. This effect is prevented by Pgp inhibitors verapamil and cyclosporin A, as well as siRNA to ABCB1, with concomitant re-sensitization to silvestrol. Together, these data indicate that silvestrol is a substrate of Pgp, a potential obstacle that must be considered in the development of silvestrol for oral delivery or targeting to tumors protected by Pgp overexpression.