DIFFERENTIAL MODULATION OF P-GLYCOPROTEIN TRANSPORT BY PROTEIN-KINASE INHIBITION
DIFFERENTIAL MODULATION OF P-GLYCOPROTEIN TRANSPORT BY PROTEIN-KINASE INHIBITION
复制标题
DOI：
10.1021/bi00086a022
复制
发表时间：
1993-09-07
期刊：
影响因子：
2.9
通讯作者：
FOJO, AT
中科院分区：
文献类型：
--
作者：
BATES, SE;LEE, JS;FOJO, AT
以往对P-糖蛋白的研究表明，它的功能可以通过磷酸化来调节。在本研究中，用Calphostin C或Stauroporine抑制蛋白激酶C或用佛波酯TPA延长治疗时间会减少P-糖蛋白的磷酸化，并损害长春花碱的转运。Calphostin C还抑制放线菌素D、长春新碱、罗丹明和齐多卡因在SW620 AD300多药耐药人结肠癌细胞中的转运。Calphostin C降低了P-糖蛋白与叠氮多宾的光亲和标记，表明去磷酸化改变了P-糖蛋白与其底物的亲和力。用星形孢子素处理的正常T淋巴细胞的罗丹明转运受损表明，P-糖蛋白功能的调节并不局限于体外选择耐药的细胞。Caphostin C也影响P-糖蛋白拮抗剂在SW620 AD300细胞中的转运，环孢素A转运减少，维拉帕米转运增加。在Calphostin C处理的细胞中，环孢素A可引起P-糖蛋白拮抗剂的相加作用，而维拉帕米则无相加作用，提示维拉帕米转运增加使其成为一种较差的P-糖蛋白拮抗剂。这些研究表明，P-糖蛋白的转运是一个受磷酸化调控的动态过程，在不同的磷酸化状态下，拮抗剂可能会不同地阻断P-糖蛋白。
Previous studies of P-glycoprotein have demonstrated that its function can be modulated by phosphorylation. In the present study, inhibition of protein kinase C with calphostin C or stauroporine or prolonged treatment with the phorbol ester TPA decreased phosphorylation of P-glycoprotein, and impaired transport of vinblastine. Calphostin C also inhibited transport of actinomycin D, vincristine, rhodamine, and azidopine in SW620 Ad300 multidrug-resistant human colon carcinoma cells. Photoaffinity labeling of P-glycoprotein with azidopine was decreased by calphostin C, suggesting that dephosphorylation alters the affinity of P-glycoprotein for its substrates. Impaired transport of rhodamine in normal T lymphocytes treated with staurosporine demonstrates that modulation of P-glycoprotein function is not limited to cells selected for drug resistance in vitro. Transport of P-glycoprotein antagonists in SW620 Ad300 cells was also affected by calphostin C. Cyclosporin A transport decreased, while verapamil transport increased. Cyclosporin A in calphostin C-treated cells resulted in additive P-glycoprotein antagonism, while no additive effect could be demonstrated with verapamil, suggesting that the increase in verapamil transport makes it a poorer P-glycoprotein antagonist. These studies suggest that transport by P-glycoprotein is a dynamic process which can be modulated by phosphorylation, and that antagonists may block P-glycoprotein differently in different phosphorylation states.