Development of anti-lung cancer drugs overcoming drug resistance mediated by new molecules a drug efflux pump, breast cancer resistance protein (BCRP), and topoisomerase-I inhibitor

我们已经发现乳腺癌耐药蛋白(BCRP)/ABCG2的一半ABC转运体是抗肺癌药物拓扑异构酶I抑制剂的相对特异性转运体（Biochem Biophys Research comm280:1216- 1223,2001）。此外，我们还报道了BCRP/ABCG2直接与药物相互作用，然后通过使用过表达BCRP的质膜囊泡将其输出细胞（BiochemBiophys Res common 288:827-832, 2001）。这些发现是BCRP生化分析的首次报道。随后，为了探讨BCRP/ABCG2在肺癌中的临床作用，我们对非小细胞肺癌（NSCLC）临床标本和培养细胞中BCRP的表达和功能进行了分析。结果表明，细胞系中BCRP mRNA的表达水平与BCRP功能以及对拓扑异构酶I抑制剂SN-38和拓扑替康的敏感性显著相关，并且一些非小细胞肺癌组织表达足够水平的BCRP mRNA，从而在体外产生耐药性（clinin Cancer Res, 2003）。基于以上发现，为了开发克服bcrp介导的耐药的新抗癌药物，我们合成了大约30种新的SN-38衍生物。利用质膜囊泡对这些衍生物进行了生物化学测试，以确定它们是否克服了耐药性。因此，我们证明了低极性喜树碱衍生物是克服耐药的有效先导化合物，并提供了发现新药的实用方法（Int J Cancer 110:921-927, 2004）。另一方面，为了逆转bcrp介导的耐药，我们研究了新生物素（一种古霉素抗生素）在bcrp过表达癌细胞中的逆转作用。新生物素通过竞争性抑制BCRP功能增加细胞内拓扑替康的积累[J] .国际肿瘤学杂志108:146-151,2004。研究结果表明，在临床可接受的浓度下，新生物素可以有效克服bcrp介导的耐药。非常有趣的是，我们证明了一种用于肺癌的新型分子靶向药物吉非替尼逆转了BCRP介导的癌细胞耐药，吉非替尼是BCRP的底物（cancer Res 65:1541-1546, 2005）。然而，我们发现吉非替尼本身不通过BCRP转运，而是通过表达BCRP的质膜囊转运。FR901228是一种新型的HDAC抑制剂，在多种肿瘤细胞中显示出抗肿瘤作用。我们证明FR901228在非常低的浓度下非常有效地抑制小细胞肺癌细胞和耐药亚群的增殖（国际癌症杂志104:238- 242,2003）。此后，我们提出FR901228通过线粒体途径而不是死亡受体途径诱导caspase依赖性细胞凋亡（Mol Cancer Ther 3:1397-1402, 2004）。考虑到BCL-2和BCL-XL可能对多重耐药的贡献，FR901228在治疗难治性和原发性小细胞肺癌方面是一种很有前景的药物。少

We have explored that breast cancer resistance protein (BCRP)/ABCG2 of a half ABC transporter is a relatively specific transporter for topoisomerase I inhibitors of anti-lung cancer drugs (Biochem Biophys Research Commun 280:1216-1223, 2001). In addition, we have reported that BCRP/ABCG2 interacted directly with drugs and then immediately exported them out of cells, by using plasma membrane vesicles ovemxpressing BCRP (BiochemBiophys Res Commun 288:827-832, 2001). These findings were the first reports in biochemical analyses of BCRP.Thereafter, to explore the clinical role of BCRP/ABCG2 in lung cancer, we did expression and functional analyses of BCRP in clinical specimens and culture cells of non-small cell lung cancer (NSCLC). The results were that the levels of BCRP mRNA expression in the cell lines were significantly correlated with the BCRP function and the sensitivity to SN-38 and topotecan of topoisomerase I inhibitors, and that some NSCLC tissues expressed sufficient levels of … More the BCRP mRNA to confer drug resistance in vitro (Clin Cancer Res 9:3052-3057, 2003).Based on the above findings, to develop new anticancer drugs overcoming BCRP-mediated drug resistance, we synthesized about thirty of new derivatives of SN-38. These derivatives were biochemically tested whether they overcame the resistance by using plasma membrane vesicles. Consequently, we demonstrated that low-polarity camptothecin derivatives were potent lead compounds to overcome the resistance, and provided a practical approach to discover new drugs (Int J Cancer 110:921-927, 2004). On the other hand, to reverse BCRP-mediated drug resistance, we examined the reversal effects of novobiocin, a coumermycin antibiotic, in BCRP-over expressing cancer cells. Novobiocin significantly increased intracellular topotecan accumulation by competitive inhibition of BCRP function (Int J Cancer 108:146-151,2004). The findings suggested that novobiocin effectively overcame BCRP-mediated drug resistance at clinically acceptable concentrations. Very interestingly, we demonstrated that gefitinib of a novel molecular target drug for lung cancer reversed BCRP-mediated drug resistance in cancer cells and that gefitinib was a substrate for BCRP (Cancer Res 65:1541-1546, 2005). However, we found that gefitinib itself was not tranported by BCRP, using plasma membrane vesicles expressing BCRP.FR901228 is a novel his tone deacetylase (HDAC) inhibitor and shows antitumor effects in various cancer cells. We demonstrated that FR901228 inhibited proliferation of small-cell lung cancer cells and drug-resistant sublines very effectively at very low concentrations (Int J Cancer 104:238-242, 2003). Thereafter, we suggested that FR901228 induced caspase-dependent apoptosis via the mitochondrial pathway rather than the death receptor pathway (Mol Cancer Ther 3:1397-1402, 2004). Considering the possible contributions of BCL-2 and BCL-XL to multidug resistance, FR901228 is a promising agent in the treatment of refractory as well as primary small-cell lung cancer. Less