Expression of the multidrug resistance-associated protein (MRP) gene in urothelial carcinomas

The intrinsic or acquired resistance of urothelial cancer to chemotherapy is one major obstacle to successful treatment. Generally, the expression level of P-glycoprotein in urothelial cancer is low, so we accordingly investigated the expression of multidrug resistance-associated protein (MRP). We examined the expression of MRP mRNA by means of slot-blotting samples of 11 renal pelvic and/or ureteral tumors, 33 bladder tumors, one lung metastasis from a ureter tumor, 7 non-cancerous urothelia from patients with transitional-cell carcinoma (TCC) and one urothelium from a patient with renal-cell carcinoma (RCC). We also estimated, by Southern blotting, whether or not the MRP gene was amplified in clinical specimens that overexpressed MRP mRNA. MRP was detected immunohistochemically using a polyclonal antibody against MRP. In all, 5 of 11 renal pelvic and/or ureter tumors (45.5%), 17 of 33 bladder tumors (51.5%) and 4 of 7 non-cancerous urothelia of TCC patients (57.1%) expressed more than 2-fold the MRP mRNA levels of drug-sensitive human KB cells. There was no significant difference in the MRP mRNA level between primary and recurrent tumors. Low-grade urothelial carcinomas (G1 and G2 TCCs) expressed significantly higher levels of MRP mRNA than the high-grade G3 TCC. The MRP gene was not amplified in urothelial carcinomas, irrespective of their expression levels of MRP mRNA. Immunohistochemically, MRP was located mainly on the plasma membrane, but also detected on the cytoplasm of cancer cells. MRP may be one mechanism responsible for intrinsic drug resistance in low-grade urothelial cancer. © 1996 Wiley-Liss, Inc.     

食管鳞癌多药耐药相关蛋白表达的研究

目的:观察24例食管癌组织及食道正常组织MRP的表达.方法:采用RT-PCR方法.结果:75. 0%的食管癌组织表达MRP,29.2%的食管正常组织表达MRP,两者有明显差异(P=0.0039),分析24例食管癌MRP的表达情况,可以看到:MRP的表达与临床分期、癌细胞的分化程度无明显关系.结论:大多数食管癌组织表达MRP,MRP的表达可能与食管癌的先天耐药有关.     

Expression of the multidrug resistance-associated protein (MRP) gene in primary non-small-cell lung cancer

BACKGROUND: One of the major problems in the cure of advanced non-small-celllung cancer (NSCLC) is its lack of re sponse to cytotoxic drugtreatment, and the mechanisms underlying this intrinsic drugresistance are unclear. PATIENTS AND METHODS: We determined the expression of a newly recognised drug resistancegene, the Multidrug Resistance-associated Protein (MRP) gene,in normal lung tissue and in tumour biopsies from 35 surgicallyresected NSCLCs (11 adenocarcinomas, 24 squamous cell carcinomas).MRP mRNA levels were quantitated by RNase protection assay andexpression of the MRP Mr 190,000 glycoprotein was estimatedby immunohistochemistry. RESULTS: Using the MRP-speciflc monoclonal antibody MRPr1, MRP expressionwas detected by immunohistochemistry in epithelial cells liningthe bronchi in normal lung. In NSCLC approximately 35% of thesamples showed elevat ed MRP mRNA levels. Based on MRP-specificimmunohis tochemical staining the tumours were divided into4 groups: 12% were scored as negative (–), 14% showedweak cytoplasmic staining of the tumour cells (±), 40%had a clear cytoplasmic staining (±), and in 34% a strongcytoplasmic as well as membranous staining was observed (++).MRP expression, as estimated by immunohistochemistry, correlatedwith the MRP mRNA levels quantitated by RNase protection assay(correlation coefficient -0.745, p=0.0009), with MRP mRNA levels(mean ± SD) of 3.0 ± 1.0 U, 3.5 ± 0.7 U,7.5 ± 5.9 U, and 19.3 ± 10.7 U, in the (–),(±), (+), and (++) immunohistochemistry expression groups,respectively. Among the squamous cell carcinomas a correlationwas observed between MRP staining and tumour cell differentiation:the strongest MRP staining was predominantly found in the welldifferentiated tumours. CONCLUSIONS: Hyperexpression of MRP is frequently observed in primary NSCLC,especially in the well differentiated squamous cell carcinomas.Further studies are needed to assess the role of MRP in themechanism of clinical drug resistance in NSCLC. MRP, NSCLC, RNase protection assay, immunohistochemistry     

多药耐药相关蛋白及肺耐药蛋白在人直肠癌组织中的表达及临床 …

目的 检测多药耐药相关蛋白（ＭＲＰ）及肺耐药蛋白（ＬＲＰ）在人直肠癌组织中的表达,探讨其与临床分期、分化程度及预后的关系。方法 采用免疫组织化学技术法检测５７例人直肠癌组织中ＭＲＰ及ＬＲＰ的表达。结果 ５７例人直肠癌组织中可检测到ＭＲＰ表达者２８例,占４９．１％;ＬＲＰ表达者２４例,占４２．１％;二者同时表达者１０例,占１７．５％;有ＭＲＰ或ＬＲＰ表达者４２例,占７３．７％;两蛋白表达阳性率与肿瘤     

Expression of the multidrug-resistance-associated protein (MRP) gene in human colorectal,gastric and non-small-cell lung carcinomas

MRP has been identified as another multidrug-resistance (MDR) gene and may be involved in an alternative MDR mechanism in some solid tumors. We investigated the expression of MRP mRNA in multidrug-resistant KB sublines (KB-8-5, KB-C2, C-A40 and C-A120), human non-small-cell lung carcinomas (NSCLC), gastric and colorectal carcinomas, and compared it with that in drug-sensitive human KB cells, MRP gene expression was elevated in 8 of 9 (89%) squamous-cell carcinomas of the lung. Furthermore, MRP expression in 4 squamous-cell carcinomas (L13, 18, 19 and 20) was more than 3.6 times higher than in KB-3-I cells, and the average MRP mRNA expression level of all squamous-cell carcinomas was significantly higher than that of adenocarcinoma of the lung and of colorectal and gastric carcinomas. These results suggested that the MRP is responsible, at least in part, for drug resistance in some squamous-cell carcinomas of the lung. © 1996 Wiley-Liss, Inc.     

Alterations in expression of the multidrug resistance-associated protein (MRP) gene in high-grade transitional cell carcinoma of the bladder.

Expression of the MRP gene has been demonstrated in vitro to be a casual factor in non-P-glycoprotein-mediated multidrug resistance, and is implicated in resistance to a number of the chemotherapeutic agents currently used in the treatment of high-grade transitional cell carcinoma (TCC) of the bladder (doxorubicin, epirubicin and vinblastine). Using a sensitive RT-PCR-based technique, we have quantified MRP mRNA levels in a series of untreated TCC (n=24), normal bladder (n=5) and control tissue and cell line samples. MRP mRNA was widely expressed and detectable in all samples analysed, with considerable (up to 190-fold) variation observed between individual tumour samples. MRP mRNA levels found in TCC samples were lower than those determined for normal peripheral mononucleocyte (2.3-fold) and testis (4.1-fold) samples, previously reported to be high-expressing tissues, and varied over a similar range to that observed in normal bladder samples. Results indicate that MRP mRNA levels in a greater proportion of high-grade (G3) bladder tumours (55%, 6/11) are significantly reduced (P=0.018) compared with low- and moderate-grade (G1/2) bladder tumours (8%, 1/13), and suggest that MRP mRNA levels frequently become reduced as a consequence of tumour progression to advanced, poorly differentiated disease. No correlation was apparent between MRP and MDR1 mRNA levels, thus providing no evidence to suggest common regulation of the two genes. In a limited number of patients, no evidence was found to support a role for MRP mRNA levels as a determinant of response to chemotherapy in patients being uniformly treated with either cisplatin-methotrexate-vinblastine (n=6) or epirubicin-cisplatin-methotrexate (n=4) regimens. Similarly, no overall pattern of altered MRP mRNA expression was observed following chemotherapy in four patients from whom post chemotherapy biopsies were taken. This study provides a useful pilot investigation regarding the level, variation and pattern of MRP mRNA expression in TCC of the bladder, and suggests that further studies to establish the clinical significance of these variations are required.     

The prognostic significance of expression of the multidrug resistance-associated protein (MRP) in primary breast cancer.

In the present study, we determined the frequency and intensity of MRP protein expression by monoclonal antibody immunohistochemistry in a series of 259 resected invasive primary breast carcinomas, and we evaluated MRP immunoreactivity in relation to patient and tumour characteristics, relapse-free (RFS) and overall survival (OS). The immunostaining was graded on a semiquantitative scale that ranged from (-) to ( ). Overall, 34% of the tumours were positive for anti-MRP antibody: 19% showed weak cytoplasmic staining (+), 14% had clear cytoplasmic staining (++) and only 1% of the tumours had a strong cytoplasmic as well as membranous staining ( ). MRP expression was not related to patient''s age, menopausal status, tumour size, differentiation grade, oestrogen and progesterone receptor level or lymph node involvement. In an exploratory univariate analysis of all patients, only primary tumour size and number of lymph nodes involved were significantly associated with shortened RFS (P < 0.001 and P < 0.001 respectively) and OS (P = 0.02 and P < 0.001 respectively). In Cox univariate analysis for RFS in subgroups of patients stratified by menopausal status, tumour size, nodal status, adjuvant systemic therapy and oestrogen and progesterone receptor status, MRP expression was associated with increased risk for failure in patients with small tumours (T1), in node-negative patients and in node-positive patients who received adjuvant systemic chemotherapy with cyclophosphamide, methotrexate and 5-fluorouracil (CMF); the relative hazard rate (RHR) for relapse was increased in the presence of MRP, with RHR values with 95% confidence limits (CL) of 2.8 (1.2-6.9), 2.1 (1.0-4.2) and 2.8 (0.8-9.9) respectively. In analysis for OS, expression of MRP was also associated with increased risk for failure in patients with small tumours (T1) [RHR (95% CL) 2.3 (0.9-6.0)] and in node-positive patients who received adjuvant systemic chemotherapy with CMF [RHR (95% CL) 3.7 (0.8-17.1)] but not in node-negative patients [RHR (95% CL) 1.1 (0.4-2.6)]. In conclusion, our results show that MRP is frequently overexpressed in primary breast cancer and suggest that MRP expression might be of prognostic significance in the subgroups of patients with the more favourable prognosis, i.e. patients with small tumours and node-negative patients, as well as in the setting of adjuvant systemic chemotherapy. In primary breast cancer, MRP might be related to altered cell biological behaviour, including a more aggressive phenotype, and resistance to adjuvant systemic chemotherapy.     

EXPRESSION OF MULTIDRUG RESISTANCE-ASSOCIATED PROTEIN （MRP） AND ITS RELATIONSHIP WITH CLINICOPATHOLOGICAL FACTORS IN NON-SMALL CELL LUNG CANCER

Atpresentchemotherapyisstilloneofthemainmethodsforcontrollingtherecurrentandmetastasisofmalignanttumors.Butmultidrugresistance(MDR)isamajorobstacleinthesuccessfultreatmentofcancerbychemotherapy.Therelationshipbetweenmultidrugresistance-associatedprotein(MRP)andchemotherapyresistancehasattractedmuchattention[1].ColeseparatedakindofoverexpressingmRNAfromthemultidrugresistancehum ansmallcelllungcancer(SCLC)celllineH69ARwhichhadnooverexpressionofp-gp,andcloneditscDNA.Theproteincodedbelonge…     

Expression and clinical significance of multidrug resistance gene and multidrug resistance-associated protein gene in acute leukemia

Multidrugresistance(MDR)remainsamaj0rcauseoffailureinthechemotherapeutictreatment0facuteleukemia(AL).ClassicalMDRphenotypeisduet0overexpressionofmembrane-b0undglycoprotein(Pl7O)encodedbymultidrugresistancegene(mdrl).However,lowP-glycoproteinlevelswerefrequentlyfoundinc1inicallydrug-resistantleukemia,andl0r2indicatedthatoverexpression0fthemdrlgenecann0tbeacc0untedforallcasesofdrugresistanceinleukenda.Recently,multidrugresistance-ass0ciatedprotein(MRP)genewasfoundt0beassociatedwithdrug-res…     

多药耐药性相关蛋白在乳腺癌组织中的表达及其与预后关系

目的:研究多药耐药相关蛋白（Multidrug　resistance-associated　protein　1,MRP1）在乳腺癌组织中的表达,评估其在乳腺癌预后中的作用。方法:采用免疫组织化学方法（IHC）检测47例手术切除的乳腺癌组织中MRP1的表达,并分析其与临床、病理特征的关系及对预后的影响。结果:（1）MRP1在乳腺癌组织中的阳性表达率为85.1％（40/47例）,其中高表达者占53.2％（25/47例）;（2）腋淋巴结阳性者MRP1表达水平明显高于腋淋巴结阴性者（P<0.05）,MRP1表达与月经状况、肿瘤大小、组织分级和激素受体状况均无关（P>0.05）;（3）Kaplan-Meier生存分析结果表明MRP1表达与无病生存期明显相关（P<0.05）,但和总生存期无关（P>0.05）;（4）Cox单因素分析显示肿瘤大小和MRP1表达与无病生存期明显相关（P<0.05）,但仅有肿瘤大小和总生存期明显相关（P<0.05）;而多因素分析却显示只有腋淋巴结转移和无病生存期（P<0.01）和总生存期（P<0.05）明显相关。结论:MRP1在乳腺癌组织中具有较高的表达水平,与乳腺癌患者的无病生存期有关,而与总生存期无关。     

多药耐药相关蛋白及肺耐药蛋白在人直肠癌组织中的表达及临床意义

目的　检测多药耐药相关蛋白（ＭＲＰ） 及肺耐药蛋白（ＬＲＰ） 在人直肠癌组织中的表达,探讨其与临床分期、分化程度及预后的关系。方法　采用免疫组织化学技术法检测５７ 例人直肠癌组织中ＭＲＰ及ＬＲＰ的表达。结果　５７ 例人直肠癌组织中可检测到ＭＲＰ表达者２８ 例,占４９．１ ％ ;ＬＲＰ表达者２４ 例,占４２．１ ％ ;二者同时表达者１０ 例,占１７ ．５％ ;有ＭＲＰ或ＬＲＰ表达者４２ 例,占７３ ．７ ％ ;两蛋白表达阳性率与肿瘤分期、分化程度无显著相关（ Ｐ＞ ０ ．０５） 。ＭＲＰ表达阳性者术后生存期明显低于该蛋白阴性者（ Ｐ＜ ０．０５） ,而ＬＲＰ的表达则与预后无显著相关;两蛋白表达无明显相关性（ Ｐ＞ ０．０５） 。结论　ＭＲＰ可能是判断人直肠癌预后的指标之一,对直肠癌患者综合治疗的实施具有指导意义。     

Expression of multidrug resistance-associated protein (MRP), MDR1 and DNA topoisomerase II in human multidrug-resistant bladder cancer cell lines.

The acquisition of the multidrug resistance phenotype in human tumours is associated with an overexpression of the 170 kDa P-glycoprotein encoded by the multidrug resistance 1 (MDR1) gene, and also with a 190 kDa membrane ATP-binding protein encoded by a multidrug resistance-associated protein (MRP) gene. Human bladder cancer is a highly malignant neoplasm which is refractory to anti-cancer chemotherapy. In order to understand the mechanism underlying multidrug resistance in bladder cancer, we established three doxorubicin-resistant cell lines, T24/ADM-1, T24/ADM-2 and KK47/ADM, and one vincristine-resistant cell line, T24/VCR, from human bladder cancer T24 and KK47 cells respectively. Both T24/ADM-1 and T24/ADM-2 cells which had elevated MRP mRNA levels showed both a cross-resistance to etoposide and a decreased intracellular accumulation of etoposide. T24/VCR cells which had elevated levels of MDR1 mRNA and P-glycoprotein but not of MRP mRNA, showed cross-resistance to doxorubicin. On the other hand, KK47/ADM cells, which had elevated levels of both MRP and MDR1 mRNA and a decreased level of topoisomerase II mRNA, were found to be cross-resistant to etoposide, vincristine and a camptothecin derivative, CPT-11. Our present study demonstrates a concomitant induction of increased levels of MRP mRNA, decreased levels of topoisomerase II mRNA and decreased drug accumulation during development of multidrug resistance in human bladder cancer cells. The enhanced expression of the MRP gene is herein discussed in a possible correlation with the decreased expression of the topoisomerase II gene.     

多药耐药相关蛋白2及其在肿瘤耐药中的研究进展

肿瘤对化疗药物多药耐药是肿瘤治疗失败的重要原因之一.多药耐药的主要原因是由PgP、多药耐药相关蛋白(MRP)、肺耐药相关蛋白(LRP)、乳腺癌耐药相关蛋白(BCRP)等转运蛋白表达异常增高所致.MRP包含9个成员:MRP1-MRP9.多药耐药相关蛋白2(MRP2)是三磷酸腺苷(ATP)结合盒运载体蛋白家族成员之一,本文就MRP2基因的特性及其在肿瘤耐药中的作用作一综述.     

Modulation of multidrug resistance-associated protein 1 (MRP1) by p53 mutant in Saos-2 cells

The p53 tumor suppressor gene is one of the most frequently mutated genes in human cancer and the mutation is correlated with a poor prognosis in cancer therapy. Upregulation of multidrug resistance-associated protein 1 (MRP1) and increase in drug resistance have been found to be induced by p53 mutation. Human osteosarcoma Saos-2 cells, a p53-null cell line, was transfected with p53 with mutations at codon 143 (V to A), 175 (R to H), 248 (R to W), 273 (R to H) and 281 (D to G). Among the different transfectants, overexpression (about 42-fold) of MRP1 was detected in p53-R175H cells. Furthermore, the p53-R175H cells were 2.5-fold more resistant to doxorubicin (DOX) and had a 4-fold greater DOX efflux rate than the control cells 1 h after DOX treatment. Transfection with antisense MRP1 oligonucleotides demonstrated a DOX sensitization effect (about 2-fold) in p53-R175H transfectants but not in control cells. In addition, transfection with antisense p53 oligonucleotides greatly suppressed MRP1 expression and reversed DOX resistance in p53-R175H cells but had no effect in control cells. The results suggested that p53-R175H might induce MRP1 expression and DOX resistance in cells.