Giaccone G, van Ark-Otte J, Rubio G J, Gazdar A F, Broxterman H J, Dingemans A M, Flens M J, Scheper R J, Pinedo H M
Department of Oncology, University Hospital Vrije Universiteit, Amsterdam, The Netherlands.
Int J Cancer. 1996 Jun 11;66(6):760-7. doi: 10.1002/(SICI)1097-0215(19960611)66:6<760::AID-IJC9>3.0.CO;2-Y.
The multidrug resistance-associated protein (MRP), a new membrane transporter related to non-Pgp multidrug resistance, is overexpressed in some drug-selected cancer-cell lines. The role of MRP in unselected cell lines and in human cancer is unknown. MRP gene expression, determined by RNase protection assay and chemosensitivity to doxorubicin, etoposide and cisplatin, determined by MTT assay, were assessed in 18 non-drug-selected lung-cancer cell lines (10 small-cell lung cancer, 6 non-small-cell lung cancer, and 1 carcinoid). MRP gene expression was also investigated in normal lung tissue and primary non-small-cell lung cancer. All cell lines except one and all normal lung tissues and primary non-small-cell lung cancers expressed detectable levels of MRP. Expression was significantly lower in cell lines than in normal and neoplastic lung. MRP protein expression was also assessed by immunohistochemistry using the monoclonal antibody MRPr1; comparable levels of expression were observed between mRNA and protein in cell lines; however, in tumor samples intense staining was observed in tumor cells as well as in infiltrating normal cells in tumors, making the results less comparable to those obtained by RNase expression. MRP expression did not directly correlate with function in a calcein accumulation assay in 2 unselected cell lines. No gene amplification was observed by Southern-blot analysis, in the unselected cell lines or in tumor samples. In general, in cell lines, MRP gene expression was correlated with lower chemosensitivity to doxorubicin and etoposide, but not to cisplatin. However, MRP expression did not directly correlate with MRP function as assessed by a calcein accumulation assay in one of 2 unselected cell lines examined. Our results suggest that MRP may be implicated in drug resistance in unselected lung-cancer cell lines and its role in normal lung and primary lung cancer warrants further investigation in patients undergoing chemotherapy.
多药耐药相关蛋白（MRP）是一种与非P糖蛋白多药耐药相关的新型膜转运蛋白，在一些经药物筛选的癌细胞系中过度表达。MRP在未经筛选的细胞系和人类癌症中的作用尚不清楚。通过核糖核酸酶保护试验测定MRP基因表达，并通过MTT试验测定对阿霉素、依托泊苷和顺铂的化学敏感性，对18个未经药物筛选的肺癌细胞系（10个小细胞肺癌、6个非小细胞肺癌和1个类癌）进行了评估。还对正常肺组织和原发性非小细胞肺癌中的MRP基因表达进行了研究。除一个细胞系外，所有细胞系以及所有正常肺组织和原发性非小细胞肺癌均表达可检测水平的MRP。细胞系中的表达明显低于正常和肿瘤性肺组织。还使用单克隆抗体MRPr1通过免疫组织化学评估MRP蛋白表达；在细胞系中观察到mRNA和蛋白之间的表达水平相当；然而，在肿瘤样本中，在肿瘤细胞以及肿瘤中的浸润正常细胞中均观察到强烈染色，使得结果与通过核糖核酸酶表达获得的结果不太可比。在2个未经筛选的细胞系的钙黄绿素积累试验中，MRP表达与功能没有直接相关性。在未经筛选的细胞系或肿瘤样本中，通过Southern印迹分析未观察到基因扩增。一般来说，在细胞系中，MRP基因表达与对阿霉素和依托泊苷的较低化学敏感性相关，但与顺铂无关。然而，在所检测的2个未经筛选的细胞系之一中，通过钙黄绿素积累试验评估，MRP表达与MRP功能没有直接相关性。我们的结果表明，MRP可能与未经筛选的肺癌细胞系中的耐药有关，其在正常肺组织和原发性肺癌中的作用值得在接受化疗的患者中进一步研究。
