Sharom F J, Yu X, DiDiodato G, Chu J W
Guelph-Waterloo Centre for Graduate Work in Chemistry, Department of Chemistry and Biochemistry, University of Guelph, Ontario, Canada.
Biochem J. 1996 Dec 1;320 ( Pt 2)(Pt 2):421-8. doi: 10.1042/bj3200421.
P-Glycoprotein functions as an ATP-driven active efflux pump for many natural products and chemotherapeutic drugs. Hydrophobic peptides have been shown to block drug uptake by P-glycoprotein, indicating that they might be transport substrates. The present study examines the interaction of the synthetic peptide series NAc-LnY-amide with the multidrug transporter. Several peptides in this series caused up to 3.5-fold enhancement of colchicine accumulation in membrane vesicles from multidrug resistant (MDR) cells, which suggests the existence of novel interactions between the binding sites for peptides and drug. Peptides did not stimulate vinblastine transport, which was inhibited as expected for competing substrates. These peptides displayed modest stimulatory effects on the ATPase activity of P-glycoprotein. None blocked azidopine photoaffinity labelling, showing that they probably occupy a binding site separate from that for the drug. Studies with 125I-labelled NAc-LLY-amide showed that it was transported by P-glycoprotein in both membrane vesicles and reconstituted proteoliposomes. Uptake of the peptide was rapid, saturable, osmotically sensitive and occurred against a concentration gradient. The enhancing effect of NAc-LLY-amide on colchicine transport was reciprocated, i.e. colchicine greatly increased the transport of labelled peptide by P-glycoprotein. Peptide transport was also modulated, both positively and negatively, by other MDR spectrum drugs. It is concluded that linear hydrophobic peptides are indeed transported by P-glycoprotein, and some have interactions with drug substrates that result in mutual stimulation of transport.
P-糖蛋白作为一种由ATP驱动的主动外排泵，作用于许多天然产物和化疗药物。疏水性肽已被证明可阻断P-糖蛋白对药物的摄取，这表明它们可能是转运底物。本研究考察了合成肽系列NAc-LnY-酰胺与多药转运蛋白的相互作用。该系列中的几种肽使多药耐药（MDR）细胞膜囊泡中秋水仙碱的蓄积增强了3.5倍，这表明肽结合位点与药物之间存在新的相互作用。肽并未刺激长春碱的转运，而长春碱的转运如预期那样受到竞争性底物的抑制。这些肽对P-糖蛋白的ATP酶活性表现出适度的刺激作用。没有一种肽能阻断叠氮平光亲和标记，这表明它们可能占据了与药物不同的结合位点。对125I标记的NAc-LLY-酰胺的研究表明，它在膜囊泡和重组蛋白脂质体中均可被P-糖蛋白转运。肽的摄取迅速、可饱和、对渗透压敏感，且是逆浓度梯度进行的。NAc-LLY-酰胺对秋水仙碱转运的增强作用是相互的，即秋水仙碱极大地增加了P-糖蛋白对标记肽的转运。肽的转运也受到其他MDR谱药物的正向和负向调节。结论是线性疏水性肽确实可被P-糖蛋白转运，并且一些肽与药物底物存在相互作用，导致转运的相互刺激。
