Marbeuf-Gueye C, Salerno M, Quidu P, Garnier-Suillerot A
Laboratoire de Physicochimie Biomoléculaire et Cellulaire (ESA CNRS 7033), Université Paris Nord, 74 rue Marcel Cachin, Bobigny, France.
Eur J Pharmacol. 2000 Mar 17;391(3):207-16. doi: 10.1016/s0014-2999(00)00047-9.
Multidrug resistance phenotype in mammalian cells is often correlated with overexpression of P-glycoprotein or Multidrug Resistance-Associated protein (MRP(1)). Both proteins are energy-dependent drug efflux pumps that efficiently reduce the intracellular accumulation and hence the cytotoxicity of many natural cytotoxins. Overexpression of these transporters by tumor cells is thought to be a significant factor in both intrinsic and acquired resistance to anticancer drugs. Consequently a great deal of interest is focused on identifying chemical agents that can either antagonise drug transport by these proteins or that can inhibit the proliferation of tumors cells despite the expression of these transporters. P-glycoprotein-mediated multidrug resistance is reversed by a variety of compounds, but surprisingly, few agents reverse the MRP(1)-mediated multidrug resistance. However, it has recently been shown that 2-[4-(diphenylmethyl)-1-piperazinyl]ethyl-5-(trans-4,6-dimethyl-1, 3, 2-dioxaphosphorinan-2-yl)-2, 6-dimethyl-4-(3-nitrophenyl)-3-pyridinecarboxylate P oxide (PAK-104P) was able to inhibit the P-glycoprotein and MRP(1)-mediated efflux of several compounds. Understanding of the interactions between transporters and multidrug resistance reversing agents is important in the design of more effective multidrug resistance modulators. We now examined the effect of PAK-104P on Pgp-and MRP1-mediated efflux of three anthracyclines, daunorubicin, pirarubicin, hydroxydoxorubicin and of calcein acetoxymethyl ester and calcein. Our data show that PAK-104P non-competitively inhibits the P-glycoprotein-mediated efflux of anthracycline derivatives and calcein acetoxymethyl ester with an inhibitory constant K(I)=0. 25+/-0.05 microM. PAK-104P also non-competitively inhibits the MRP(1)-mediated efflux of daunorubicin, pirarubicin, hydroxyrubicin, calcein acetoxymethyl ester and calcein. However, surprisingly, in this case the K(I) values obtained were very different ranging from 0.06 for hydroxyrubicin to 10 microM for calcein. These data strongly suggested the existence of two different mechanisms for the inhibition by PAK-104P of the MRP(1)-mediated efflux of molecules: a first mechanism, involving a low-affinity site for PAK-104P, and which would concern molecules such as calcein, cysteinyl leukotriene LCT(4) etc. whose efflux do not depend on glutathione. A second mechanism involving a high-affinity site for PAK-104P and which would concern molecules such as anthracyclines, calcein acetoxymethyl ester whose efflux depends on the presence of glutathione.
哺乳动物细胞中的多药耐药表型通常与P-糖蛋白或多药耐药相关蛋白（MRP(1)）的过表达有关。这两种蛋白都是能量依赖性药物外排泵，能有效减少细胞内药物蓄积，从而降低许多天然细胞毒素的细胞毒性。肿瘤细胞中这些转运蛋白的过表达被认为是导致对抗癌药物产生固有耐药性和获得性耐药性的一个重要因素。因此，大量研究致力于寻找能够拮抗这些蛋白介导的药物转运，或者能够在这些转运蛋白表达的情况下抑制肿瘤细胞增殖的化学试剂。多种化合物可逆转P-糖蛋白介导的多药耐药，但令人惊讶的是，很少有试剂能逆转MRP(1)介导的多药耐药。然而，最近有研究表明，2-[4-(二苯甲基)-1-哌嗪基]乙基-5-(反式-4,6-二甲基-1,3,2-二氧磷杂环己烷-2-基)-2,6-二甲基-4-(3-硝基苯基)-3-吡啶羧酸P氧化物（PAK-104P）能够抑制P-糖蛋白和MRP(1)介导的多种化合物的外排。了解转运蛋白与多药耐药逆转剂之间的相互作用对于设计更有效的多药耐药调节剂至关重要。我们现在研究了PAK-104P对Pgp和MRP1介导的三种蒽环类药物（柔红霉素、吡柔比星、羟基柔红霉素）以及钙黄绿素乙酰甲酯和钙黄绿素外排的影响。我们的数据表明，PAK-104P非竞争性抑制蒽环类衍生物和钙黄绿素乙酰甲酯的P-糖蛋白介导的外排，抑制常数K(I)=0.25±0.05微摩尔。PAK-104P也非竞争性抑制柔红霉素、吡柔比星、羟基柔红霉素、钙黄绿素乙酰甲酯和钙黄绿素的MRP(1)介导的外排。然而，令人惊讶的是，在这种情况下获得的K(I)值差异很大，从羟基柔红霉素的0.06到钙黄绿素的10微摩尔不等。这些数据强烈表明，PAK-104P抑制MRP(1)介导的分子外排存在两种不同机制：第一种机制涉及PAK-104P的低亲和力位点，与钙黄绿素、半胱氨酰白三烯LCT(4)等分子有关，其外排不依赖于谷胱甘肽。第二种机制涉及PAK-104P的高亲和力位点，与蒽环类药物、钙黄绿素乙酰甲酯等分子有关，其外排依赖于谷胱甘肽的存在。
