Mechetner E, Kyshtoobayeva A, Zonis S, Kim H, Stroup R, Garcia R, Parker R J, Fruehauf J P
Oncotech, Inc., Irvine, California 92614, USA.
Clin Cancer Res. 1998 Feb;4(2):389-98.
To determine whether multidrug resistance (MDR1) P-glycoprotein (Pgp) expression correlated with clinical MDR1-related drug resistance, we established a protocol for quantitative measurement of Pgp expression and in vitro drug resistance in doxorubicin resistant MCF7 breast cancer cell lines and 359 freshly resected specimens of breast carcinoma. Pgp expression was detected with 4E3, UIC2, and JSB-1 monoclonal antibodies using flow cytometry and immunohistochemistry (IHC). Pgp function was determined using PSC833 in a drug resistance-reversal assay and with a three-dimensional agarose-based extreme drug resistance assay. MCF7 calibrator cell lines expressed Pgp, which was functional and in proportion to the degree of drug resistance. Flow cytometry, UIC2 shift assays, IHC scores, and determination of absorbance products by image analysis were all highly correlated (r > 0.9). Overall Pgp expression increased from 11% in untreated patients to 30% in patients who had previously received chemotherapy. Compared with Pgp-negative tumors, a significant increase in doxorubicin and Taxol resistance was seen for breast cancers that expressed Pgp, regardless of prior treatment. A strong correlation between the degree of Pgp expression and in vitro resistance to Taxol and doxorubicin (but not to 5-fluorouracil) was found when either IHC scores or image analysis-based methods were used to quantify Pgp expression (n = 185, P < 0.0001). The degree of Pgp expression strongly correlated with the degree of drug resistance in the clinical specimens studied. These data suggest that (a) Pgp contributes to clinical MDR1-related drug resistance, and (b) both intrinsic and acquired expression of Pgp in breast cancer may contribute in part to therapeutic failure and relapse.
为了确定多药耐药性（MDR1）P-糖蛋白（Pgp）的表达是否与临床MDR1相关的耐药性相关，我们建立了一种方案，用于定量测量耐阿霉素的MCF7乳腺癌细胞系和359例新鲜切除的乳腺癌标本中Pgp的表达及体外耐药性。使用流式细胞术和免疫组织化学（IHC），用4E3、UIC2和JSB-1单克隆抗体检测Pgp表达。在耐药逆转试验中使用PSC833并通过基于三维琼脂糖的极端耐药试验来确定Pgp功能。MCF7校准细胞系表达Pgp，其具有功能且与耐药程度成比例。流式细胞术、UIC2迁移试验、IHC评分以及通过图像分析测定吸光度产物均高度相关（r>0.9）。总体而言，Pgp表达从未经治疗患者中的11%增加到先前接受过化疗患者中的30%。与Pgp阴性肿瘤相比，无论先前治疗如何，表达Pgp的乳腺癌对阿霉素和紫杉醇的耐药性均显著增加。当使用IHC评分或基于图像分析的方法来量化Pgp表达时（n = 185，P < 0.0001），发现Pgp表达程度与对紫杉醇和阿霉素（但不包括5-氟尿嘧啶）的体外耐药性之间存在强相关性。在研究的临床标本中，Pgp表达程度与耐药程度密切相关。这些数据表明：（a）Pgp促成临床MDR1相关的耐药性；（b）乳腺癌中Pgp的固有表达和获得性表达可能部分导致治疗失败和复发。
