KB细胞耐药株的建立及其耐药机制的探讨

用对长春新碱(VCR)敏感的KB细胞为亲本,通过诱变剂甲基磺酸乙酯刺激,然后在培养液中加入浓度递增的CVR,得到耐药细胞株KB_V200。此细胞株对VCR的耐受程度约为KB细胞的175倍。对其它抗肿瘤药物如紫杉醇、秋水仙碱和阿霉素等也有不同程度的交叉耐药性。进一步研究表明,KB_V200对³H-VCR的蓄积明显减少,且耐药基因(mdr1)表达增加。钙通道阻滞剂维拉帕米(Ver)可增加KB_V200对³H-VCR的蓄积和对VCR的敏感性。这些结果提示,KB_V200耐药的机制可能是由于mdr1基因表达增加,产生过量的p-糖蛋白,使药物外排增多所致。

VINCRISTINE-RESISTANT HUMAN KB CELL LINE AND MECHANISM OF MULTIDRUG RESISTANCE

A multidrug-resistant(mdr)clone of human cancer KB cells was isolated by step-wise selection on exposure to increasing doses of vincristine. The final clone ,KBV200 ,obtained afterethylmethane sulfonate(EMS)mutagenesis showed 175-fold higher resistance to vincristine than didKB crlls. The cells were also cross-resistant to taxol, colchicine and adriamycin. Cellular accumlation of vincristine in KBV200 was decreased to less than one-fifth of that in KB.To determine the presence of mdr 1 mRNA in KBV200 and KB ,total cellular RNAs from each cell linewere analyzed by means of slot blot hybridization The result showed that the mdr 1 gene had beenhighly expressed in KBV200. In addition , verapamil,a calcium channel blockers ,was shown to increase VCR accumulation inKBV200 and reverse the vincristine resistance. All these results demonstrate that the mechanism ofKBV200 cell resistance to multiple drugs resulted from increased expression of mdr 1 gene and brought about over production of P-glycoprotein and increased the efflux of drugs.