Alvarez M, Robey R, Sandor V, Nishiyama K, Matsumoto Y, Paull K, Bates S, Fojo T
Departamento Hematologia-Oncologia, Universidad Catolica de Chile, Santiago, Chile.
Mol Pharmacol. 1998 Nov;54(5):802-14. doi: 10.1124/mol.54.5.802.
The MRP gene contributes to one form of multidrug resistance. To identify drugs interacting with MRP, we measured MRP mRNA expression by quantitative PCR in 60 cell lines of the National Cancer Institute Anticancer Drug Screen. Expression was detected in all cell lines (highest in lung carcinomas and central nervous system tumors) with a range of 14-fold. A mean graph of MRP mRNA levels was constructed to determine Pearson correlation coefficients (PCCs) with mean graphs of >40,000 compounds using the COMPARE analysis. Only 20 compounds had PCCs of >/=0.500. The PCCs for VP-16, doxorubicin, and vincristine were 0.008, 0.13, and 0.257, respectively. Initially, 36 compounds with PCCs of >/=0.428 were analyzed using two MRP-overexpressing cell lines; low levels of cross-resistance was demonstrated for 23 compounds (1.3-9.4-fold). Twenty-four compounds also were available for further studies. Using a fluorescence activated cell sorter assay to measure competition of calcein efflux from MRP-overexpressing cells, 10 compounds were found to increase calcein retention by >/=2-fold. Ten compounds also were able to reduce ATP-dependent [3H]LTC4 transport into vesicles from MRP-overexpressing cells. These results contrast with previous studies with MDR-1 in which high correlations were found and confirmed for a large number of compounds. Although other assays may be more revealing, in these unselected cell lines, MRP mRNA expression was a poor predictor of drug sensitivity. This raises the possibility that other factors, including conjugating enzymes, glutathione levels, or other transporters, confound the MRP effect.
多药耐药相关蛋白（MRP）基因导致了一种形式的多药耐药。为了鉴定与MRP相互作用的药物，我们通过定量PCR在国立癌症研究所抗癌药物筛选的60种细胞系中测量了MRP mRNA的表达。在所有细胞系中均检测到表达（在肺癌和中枢神经系统肿瘤中最高），表达范围为14倍。构建了MRP mRNA水平的均值图，以使用COMPARE分析确定与40,000多种化合物的均值图的皮尔逊相关系数（PCC）。只有20种化合物的PCC≥0.500。依托泊苷、阿霉素和长春新碱的PCC分别为0.008、0.13和0.257。最初，使用两种MRP过表达细胞系分析了36种PCC≥0.428的化合物；23种化合物（1.3 - 9.4倍）表现出低水平的交叉耐药。另外24种化合物也可用于进一步研究。使用荧光激活细胞分选仪检测来测量从MRP过表达细胞中排出钙黄绿素的竞争情况，发现有10种化合物使钙黄绿素保留增加≥2倍。还有10种化合物能够减少ATP依赖的[3H]白三烯C4转运进入MRP过表达细胞的囊泡。这些结果与先前对多药耐药基因1（MDR - 1）的研究形成对比，在先前的研究中发现并证实了大量化合物与MDR - 1有高度相关性。尽管其他检测方法可能更具揭示性，但在这些未经过筛选的细胞系中，MRP mRNA表达对药物敏感性的预测能力较差。这增加了包括结合酶、谷胱甘肽水平或其他转运蛋白在内的其他因素混淆MRP效应的可能性。
