Shepard Robert L, Cao Jin, Starling James J, Dantzig Anne H
Lilly Research Laboratories, Lilly Corporate Center, Indianapolis, IN 46285, USA.
Int J Cancer. 2003 Jan 1;103(1):121-5. doi: 10.1002/ijc.10792.
Our study examines the ability of LY335979 (Zosuquidar trihydrochloride) to modulate 3 distinct ABC transporters that are mechanisms of drug resistance: P-glycoprotein (Pgp, ABCB1), multidrug resistance associated protein (MRP1, ABCC2) and breast cancer resistance protein (BCRP, ABCG2). Pgp-mediated resistance can be modulated by coadministration with the highly potent, selective inhibitor, LY335979. Modulation of resistance by mitoxantrone and vinorelbine, 2 drugs used to treat certain solid tumors, was examined in a 3-day cytotoxicity assay using a panel of HL60 leukemia cell lines or MCF-7 breast cancer transfectants. LY335979, at 0.5 microM, substantially reversed mitoxantrone resistance and fully reversed vinorelbine resistance of Pgp-expressing HL60/Vinc cells. However, LY335979 did not modulate drug resistance in the MRP1-expressing HL60/ADR or drug-sensitive parental HL60 cells. To ascertain if LY335979 modulates BCRP-mediated drug resistance, the sensitivity of 26-fold mitoxantrone resistant, BCRP-transfected MCF-7 cells was evaluated. Addition of 5 microM LY335979, a concentration approximately 100-fold higher than the affinity of Pgp, had little to no effect on the BCRP transfectant. [(125)I]Iodomycin photolabeled Pgp in CEM/VLB(100) membranes and was inhibited by 5 microM LY335979 and GF120918. No photolabeling of MRP or BCRP occurred in H69AR or MCF-7/BCRP membranes, respectively. These results further demonstrate that LY335979 is highly specific for Pgp and does not modulate MRP1- or BCRP-mediated resistance and can be used in combination with mitoxantrone and vinorelbine in tumor cells.
我们的研究考察了LY335979（三盐酸唑苏喹达）调节3种不同的ABC转运蛋白的能力，这些转运蛋白是耐药机制：P-糖蛋白（Pgp，ABCB1）、多药耐药相关蛋白（MRP1，ABCC2）和乳腺癌耐药蛋白（BCRP，ABCG2）。Pgp介导的耐药性可通过与高效、选择性抑制剂LY335979联合给药来调节。在一项为期3天的细胞毒性试验中，使用一组HL60白血病细胞系或MCF-7乳腺癌转染细胞，检测了用于治疗某些实体瘤的两种药物米托蒽醌和长春瑞滨对耐药性的调节作用。在0.5微摩尔浓度下，LY335979可显著逆转表达Pgp的HL60/Vinc细胞对米托蒽醌的耐药性，并完全逆转其对长春瑞滨的耐药性。然而，LY335979并未调节表达MRP1的HL60/ADR细胞或药物敏感的亲本HL60细胞的耐药性。为了确定LY335979是否调节BCRP介导的耐药性，评估了对米托蒽醌耐药26倍的BCRP转染MCF-7细胞的敏感性。添加5微摩尔的LY335979（该浓度比Pgp的亲和力高约100倍）对BCRP转染细胞几乎没有影响。[125I]碘霉素可对CEM/VLB(100)细胞膜中的Pgp进行光标记，并被5微摩尔的LY335979和GF120918抑制。在H69AR或MCF-7/BCRP细胞膜中，分别未出现MRP或BCRP的光标记。这些结果进一步证明，LY335979对Pgp具有高度特异性，不会调节MRP1或BCRP介导的耐药性，可与米托蒽醌和长春瑞滨联合用于肿瘤细胞。
