Shi T, Wrin J, Reeder J, Liu D, Ring D B
Department of Immunotherapeutics, Chiron Corporation, Emeryville, California 94608, USA.
Clin Immunol Immunopathol. 1995 Jul;76(1 Pt 1):44-51. doi: 10.1006/clin.1995.1086.
Cancer patients treated with one anticancer agent often develop resistance to a broad spectrum of chemotherapeutic agents. This type of multiple drug resistance (MDR) is often accompanied by a decrease in drug accumulation and an increase in expression of a 170,000-Da plasma membrane glycoprotein (P-170) that can effectively pump various anticancer agents out of cytoplasm. A panel of 12 IgG1, IgG2a, or IgG2b monoclonal antibodies was generated against the extracellular portion of P-glycoprotein by immunizing mice with a human MDR1 gene-transfected BA3T3 fibroblast line. We have characterized two of the anti-P-glycoprotein monoclonal antibodies, 15D3 and 17F9, in some detail. Both antibodies immunoprecipitate a 170- to 180-kDa protein from MDR cells, but do not block binding of the known anti-P-glycoprotein antibody MRK16, suggesting that 15D3 and 17F9 bind to a different epitope on the extracellular domain of P-glycoprotein than MRK16. Scatchard analysis revealed that 15D3 and 17F9 had association constants of 1.3 and 1.1 x 10(8) M-1, respectively. 15D3 and 17F9 had little effect on MDR cell growth except for a minor inhibition of KB-V1 cells when the cells were incubated in the presence of vinblastine. Neither antibody inhibited the efflux of P-glycoprotein substrates from MDR cells. Because of their strong binding activity, these antibodies may be useful for diagnostic detection of MDR in patients undergoing chemotherapy or as targeting components of immunotherapeutic agents.
接受单一抗癌药物治疗的癌症患者常常会对多种化疗药物产生耐药性。这种多药耐药性（MDR）通常伴随着药物蓄积减少以及一种170,000道尔顿的质膜糖蛋白（P - 170）表达增加，该糖蛋白能够有效地将各种抗癌药物泵出细胞质。通过用人MDR1基因转染的BA3T3成纤维细胞系免疫小鼠，制备了一组12种IgG1、IgG2a或IgG2b单克隆抗体，这些抗体针对P - 糖蛋白的细胞外部分。我们已经较为详细地对两种抗P - 糖蛋白单克隆抗体15D3和17F9进行了特性分析。两种抗体都能从MDR细胞中免疫沉淀出一种170至180 kDa的蛋白质，但不阻断已知抗P - 糖蛋白抗体MRK16的结合，这表明15D3和17F9与P - 糖蛋白细胞外结构域上的表位结合位点与MRK16不同。Scatchard分析显示，15D3和17F9的结合常数分别为1.3和1.1×10(8) M-1。15D3和17F9对MDR细胞生长影响很小，只有在长春碱存在下孵育细胞时，对KB - V1细胞有轻微抑制作用。两种抗体均未抑制MDR细胞中P - 糖蛋白底物的外排。由于它们具有很强的结合活性，这些抗体可能有助于对接受化疗患者的MDR进行诊断检测，或作为免疫治疗药物的靶向成分。
