蛋白激酶C与耐药性KB细胞的多药抗药性

目的 :研究蛋白激酶C(PKC)在肿瘤细胞多药抗药性的作用及机制。方法 :测定KB细胞及其耐药株的PKC活性及PKC调节剂对细胞药敏、药物代谢和耐药膜糖蛋白表达及其磷酸化的影响。结果 :耐药株胞质和胞膜的PKC活性分别是KB细胞的 6 6倍和 5 2倍 ,膜糖蛋白阳性率为 4 7 5 % ,明显高于KB细胞的 2 8% ;而且膜糖蛋白的磷酸化明显增强。耐药株对罗丹明 12 3的外排显著加快 ,蓄积明显减少。PKC激活剂佛波乙酯使耐药株的药物外排增加了 60 % ,蓄积减少了 70 % ;PKC抑制剂Stau rosprin使耐药株药物外排后潴留增加了 2 5倍 ,蓄积增加了 14倍 ,抗药性被逆转了 14倍 ,但未影响耐药膜糖蛋白的表达。结论 :PKC活性增高与耐药株抗药性密切相关 ;而且抗药性是通过膜糖蛋白磷酸化增强 ,增加药物外排 ,减少药物蓄积而实现的

Role and Mechanism of Protein Kinase C in Multidrug Resistance in KB Cells

Objective To identify role and mechanism of protein kinase C(PKC) in multidrug resistance.Methods Using the KB cell and resistant KB cell (KB/VCR) to vicristine,applying MTT assay,test drug sensitivity;PKC activity and effect of PKC modulators were studied in KB cell and KB/VCR.Flow cytometry was applied to assay PKC effect on intracellular accumulation and efflux of Rhodamine 123 and expression of P-glycoprotein.And P-gp phosphorylation was detected by autoradiography.Results PKC activity of KB/VCR are markly higher than KB cell.When treated with TPA,a PKC activator,PKC activity in KB/VCR was further increased,accompanied by 70% decrease in 2 accumulatioo of Rhodamine 123 and by 60% increase in efflux.While treated with Staurosprine,a PKC inhibitor,cytosol and membrane PKC activity in KB/VCR decreased 27% and 34% respectively,accompanied by 14 folds increase in Rhodamine 123 accumulation and 2.5 folds increase in post-efflux storage.Drug resistance was reversed by 14 folds.The P-glycoprotein expression rate for KB cell was 2.8%,while for KB/VCR 47.5%.Autoradiography was more intensive in KB/VCR then in KB cell.Conclusions KB/VCR exhibited higher Protein kinase C activity than KB cell did.Protein kinase C reduce cellular drug accumulation and increase drug efflux through modulating P-glycoprotein phosphorylation and finally result in multidrug resistance.