The expression and significance of P-glycoprotein,lung resistance protein and multidrug resistance-associated protein in gastric cancer

Background

To detect the expression of multidrug resistance molecules P-glycoprotein (P-gp), Lung resistnce protein (LRP) and Multidrug resistance-associated protein (MRP) and analyze the relationship between them and the clinico-pathological features.

Methods

The expressions of P-gp, LRP and MRP in formalin-fixed paraffin-embedded tissue sections from 59 gastric cancer patients were determined by a labbelled Streptavidin-Peroxidase (SP) immunohistochemical technique, and the results were analyzed in correlation with clinicopathological data. None of these patients received chemotherapy prior to surgery.

Results

The positive rates of P-gp, LRP, MRP were 86.4%, 84.7% and 27.1%, respectively. The difference between the positive rate of P-gp and MRP was significant statistically, as well as the difference between the expression of MRP and LRP. No significant difference was observed between P-gp and LRP, but the positively correlation between the expression of P-gp and LRP had been found. No significant correlation between the expression of P-gp, LRP, MRP and the grade of differentiation were observed. The expression of P-gp was correlated with clinical stages positively (r = 0.742), but the difference with the expression of P-gp in different stages was not significant.

Conclusion

The expressions of P-gp, LRP and MRP in patients with gastric cancer without prior chemotherapy are high, indicating that innate drug resistance may exist in gastric cancer.     

Schisandrin B: a dual inhibitor of P-glycoprotein and multidrug resistance-associated protein 1

We recently reported that schisandrin B (Sch B) was a novel P-glycoprotein (P-gp) inhibitor. In this study, we revealed that Sch B was also an effective inhibitor of multidrug resistance-associated protein 1 (MRP1). The activities of Sch B to reverse MRP1-mediated drug resistance was tested using HL60/ADR and HL60/MRP, the human promyelocytic leukemia cell lines with the overexpression of MRP1 but not P-gp. Sch B resumed daunorubicin and carboxyfluorescein diacetate (CFDA, a specific substrate for MRP1) accumulation and retention in HL60/ADR cells in a time and concentration dependent manner. At the equimolar concentration, Sch B demonstrated significantly stronger potency than probenecid, a MRP1 inhibitor. This study, together with the previous findings, demonstrated that Sch B was a dual inhibitor of P-gp and MRP1, a type suggested to be preferable to the use of combination of two specific modulators to prevent drug-drug interaction and cumulative toxicities.     

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。     

99mTc-sestamibi is a substrate for P-glycoprotein and the multidrug resistance-associated protein.

99mTc-sestamibi (99mTc-MIBI) is a substrate for the P-glycoprotein (P-gp) pump but it is not known whether it is a substrate for the multidrug resistance-associated protein (MRP) pump. Therefore, 99mTc-MIBI was evaluated in the GLC4 cell line and its doxorubicin-resistant MRP-, but not P-gp-, overexpressing GLC4/ADR sublines as well as in the S1 cell line and its MRP-transfected subline S1-MRP. 99mTc-MIBI concentration decreased in the GLC4/ADR sublines with increasing MRP overexpression and was lower in S1-MRP than in S1. 99mTc-MIBI plus vincristine increased 99mTc-MIBI concentration in GLC4 lines compared with 99mTc-MIBI alone. 99mTc-MIBI efflux raised with increasing MRP expression in the GLC4 lines. Glutathione depletion elevated 99mTc-MIBI concentration in GLC4/ADR150x. Cross resistance for 99Tc-MIBI, used to test cytotoxicity of the Tc compound, was observed in GLC4/ADR150x vs GLC4. 99Tc-MIBI induced a synergistic effect on vincristine cytotoxicity in GLC4/ADR150x. These results show that 99mTc-MIBI is involved in MRP-mediated efflux. The fact that 99mTc-MIBI efflux is influenced by MDR1 and MRP expression must be taken into account when this gamma-rays-emitting complex is tested for tumour efflux measurements.     

Reversal of drug resistance using hammerhead ribozymes against multidrug resistance-associated protein and multidrug resistance 1 gene

We examined the effects of suppressing multidrug resistance-associated protein (MRP) and multidrug resistance 1 (MDR1) gene expression in HCT-8DDP human colon cancer cell lines, which showed both cisplatin and multidrug resistance. Hammerhead ribozymes, designed to cleave MRP mRNA (anti-MRP Rz) and MDR1 mRNA (anti-MDR1 Rz), were transfected into the HCT-8DDP cells. Drug sensitivity was estimated by MTT assay in vitro. The HCT-8DDP/anti-MRP Rz cells were more sensitive to doxorubicin (DOX) and etoposide (VP-16) by 2.5- and 4.1-fold, respectively, compared with HCT-8DDP cells. The HCT-8DDP/anti-MDR Rz cells were more sensitive to DOX and VP-16 by 2.3- and 3.8-fold, respectively. The anti-MRP Rz and anti-MDR1 Rz significantly down-regulated resistance to DOX and VP-16, while anti-MRP Rz and anti-MDR1 Rz did not affect resistance to cisplatin, methotrexate and 5-fluorouracil. The hammerhead ribozyme-mediated specific suppression of MRP or MDR1 was sufficient to reverse multidrug resistance in the human colon cancer cell line.     

Functional analysis of P-glycoprotein and multidrug resistance associated protein related multidrug resistance in AML-blasts.

Despite the high effectiveness of various P-glycoprotein (P-gp) modulating substances in vitro their clinical value e.g. for combination treatment of acute myelogenous leukemias (AML) remains still unclear. This might be explainable by recent findings that other factors than P-gp (e.g. the multidrug resistance associated protein (MRP)) may also be involved in clinical occurring drug resistance. To study P-gp and MRP mediated MDR in AML blasts from patients with relapses at the functional level we measured rhodamine 123 (RHO) efflux in combination with a P-gp specific (SDZ PSC 833) or a MRP specific (MK571) modulator, respectively. Furthermore, direct antineoplastic drug action was monitored by determination of damaged cell fraction of a blast population using flow cytometry. We generally found strongly modulated RHO efflux by SDZ PSC 833 but slight RHO-efflux modulation by MK571 in blasts from relapsed states of AML expressing MDR1 or MRP mRNA at various levels. We could not demonstrate, though, significant PSC 833 or MK571 mediated modulation of the cytotoxic effects of etoposide. The results point to the possibility that combination of etoposide and a modulator might not improve responses to chemotherapy by targeting P-gp or MRP exclusively.     

Detection of multidrug resistance markers, P-glycoprotein and mdr1 mRNA, in human leukemia cells

We have examined the expression of P-glycoprotein in clinical leukemic cell samples by using a monoclonal antibody (MRK16) against P-glycoprotein. We found that leukemia cells isolated from 3 out of 6 patients with blast crisis of chronic myelogenous leukemia were reactive to MRK16. These 3 cell lines expressed high levels of mdr1 mRNA, which codes for P-glycoprotein. The present result indicates that the clinically refractory state of the tumor may be predicted in part by determining P-glycoprotein expression using the monoclonal antibody against P-glycoprotein, and the mdr1 probe.     

Inhibition of P-glycoprotein and multidrug resistance protein 1 by dietary phytochemicals

PURPOSE: For the development of a safe and effective dual inhibitor of anticancer drug efflux transporters P-glycoprotein and multidrug resistance protein 1 (MRP1) to conquer multidrug resistance, we investigated the effects of dietary phytochemicals on the functions of P-glycoprotein and MRP1. METHODS: The effects of dietary phytochemicals on the functions of P-glycoprotein and MRP1 were investigated using P-glycoprotein-overexpressing human carcinoma KB-C2 cells and human MRP1 gene-transfected KB/MRP cells. The effects of natural compounds found in dietary supplements, herbs, and foods such as sesame, ginkgo, soybean, and licorice were evaluated. RESULTS: The accumulation of daunorubicin, a fluorescent substrate of P-glycoprotein, increased in the presence of sesamin, ginkgolic acid, matairesinol, glycyrrhetinic acid, glabridin, and phyllodulcin in KB-C2 cells. Glycyrrhetinic acid and matairesinol also increased the accumulation of calcein, a fluorescent substrate of MRP1, in KB/MRP cells. KB-C2 and KB/MRP cells were sensitized to anticancer drugs by glycyrrhetinic acid, showing that glycyrrhetinic acid reverses multidrug resistance. The verapamil-stimulated P-glycoprotein ATPase activity was inhibited by glycyrrhetinic acid. Glycyrrhetinic acid stimulated the ATPase activity of MRP1. CONCLUSION: These results suggest that dietary phytochemicals, such as glycyrrhetinic acid found in licorice, have dual inhibitory effects on P-glycoprotein and MRP1 and might become useful to enhance the efficacy of cancer chemotherapy.     

蛋白激酶C及多药耐药相关蛋白在膀胱癌中的表达及意义

目的研究蛋白激酶C(PKC)及多药耐药相关蛋白在膀胱癌多药耐药中的作用。方法 采用Takai法测定膀胱癌及正常膀胱组织中PKC活性, RT-PCR法测定P-gp及MRP mRNA。结果 膀胱癌组织与癌旁组织相比较, 胞浆、胞膜中PKC活性都明显升高, 随分期、分级的增高而增高;P-gp在膀胱癌组织和癌旁组织表达率为88.9%和100%, 膀胱癌组织中的表达低于癌旁组织;MRP在所有膀胱癌组织及癌旁组织都有表达, 膀胱癌组织高于癌旁组织。P-gp在不同临床分期和病理分级之间都无差别, MRP只在不同病理分级之间有显著差异。MRP与PKC活性显著相关, P-gp与PKC无相关性。结论 膀胱癌组织细胞中PKC的过度表达促进了肿瘤多药耐药的发生;PKC在膀胱癌的多药耐药中发挥着重要的作用。     

儿童急性白血病初治患者LRP和MRP的表达及其临床意义

背景与目的:有研究发现肺耐药相关蛋白(lungresistanceprotein,LRP)和多药耐药相关蛋白(multidrugresistance鄄associatedporotein,MRP)的表达与白血病患儿耐药有关,而且患儿耐药不是由于一种耐药机制引起的。本研究旨在观察LRP和MRP在不同类型小儿白血病初治时的表达情况及其与临床疗效的关系。方法:应用逆转录鄄聚合酶链反应法(RT鄄PCR)检测38例不同类型儿童急性白血病[27例急性淋巴细胞白血病(acutelymphoblastic,ALL),11例急性非淋巴细胞白血病(acutenonlymphocyticleukemia,ANLL)]及6名正常儿童LRP、MRP基因的表达,结合患儿化疗后的完全缓解(CR)率分析两种基因表达的意义。结果:38例患儿化疗后CR26例(68.4%)。38例患儿中LRP基因表达阳性11例(28.9%),表达阴性27例(71.1%),6例正常对照儿童LRP基因阴性。LRP基因阳性患儿的CR率低于阴性者(分别为27.3%和85.2%,P<0.05)。MRP阳性者21例,6例正常对照儿童MRP基因阴性。MRP基因阳性者的CR率低于阴性者(分别为47.6%和94.1%,P<0.05)。27例ALL患儿中LRP阳性5例,11例ANLL患儿中LRP阳性6例(分别为18.5%和54.5%,P<0.05)。27例ALL患儿中MRP阳性16例;11例ANLL患儿MRP阳性5例(分别为59.3%和45.5%,P>0.05),ALL和ANLL中MRP的表达无显著性差异。LRP基因阳性患者的MRP阳性率与LRP阴性者MRP阳性率无显著性差异(分别为28.6%和29.4%,P>0.05),说明LRP基因与MRP基因之间无相关性。结论:LRP基因及MRP基因阳性儿童急性白血病者病情重、化疗缓解率低,儿童ANLL相对于ALL化疗缓解率低可能与LRP的表达有关。     

膀胱癌组织中P-糖蛋白、多药耐药相关蛋白、Bad的表达及其与临床病理的关系

目的：探讨膀胱癌组织中P-糖蛋白（P-gp）、多药耐药相关蛋白（MRP）和凋亡蛋白Bad的表达及其与临床病理之间的关系。方法：采用SP法检测67例膀胱癌组织及20例正常膀胱组织中P-gp、MRP和Bad的表达情况。结果：67例膀胱癌患者中P-gp、MRP和Bad的阳性率分别为65.7%（44/67）、58.2%（39/67）和62.7%（42/67）,而在正常膀胱粘膜中分别为10.0%（2/20）、5.0%（1/20）和5.0%（1/20）,二者比较均有统计学差异（P〈0.05）;35例初发膀胱癌组织中,P-gp、MRP和Bad阳性表达率分别为45.7%、48.6%、71.4%,与32例复发膀胱癌组织中的87.5%、68.8%、51.3%比较,亦均有显著性差异（P〈0.05）。P-gp与MRP表达无明显相关性（P〉0.05）。膀胱癌细胞分化程度越低,临床分期越高,P-gp阳性率越高（P〈0.05）,Bad表达越低,呈负相关关系。MRP与临床分期、组织分级无相关性。结论：P-gp过表达、Bad低表达在膀胱癌复发中可能具有一定的协同作用。     

卵巢癌组织中多药耐药基因蛋白表达及其临床价值

目的 :研究多个耐药基因P -糖蛋白(P gp)、谷胱甘肽S -转移酶 (GST π)、DNA拓扑异构酶 -Ⅱ (Topo Ⅱ )在卵巢癌组织中表达 ,探讨其在卵巢癌化学治疗耐药中的作用及与临床病理学特征间的关系。方法 :应用免疫组化SP法对 3 7例卵巢癌、10例卵巢良性肿瘤和 8例正常卵巢组织中P gp、GST π和Topo Ⅱ表达状况进行测定。结果 :P gp、GST π和Topo Ⅱ在卵巢癌组织中阳性表达均高于良性肿瘤和正常组织对照组 ,P<0 0 5。P gp表达与卵巢癌组织类型、分化程度、临床分期均无关 ,P >0 0 5。GST π表达与肿瘤分化程度显著相关 ,P <0 0 1;与卵巢癌组织类型无关 ,P >0 0 5。Ⅲ、Ⅳ期组织中GST π阳性表达率显著高于Ⅰ、Ⅱ期( 91 3 %vs 5 7 1% ) ,P <0 0 5。Topo Ⅱ表达仅与肿瘤分化程度有关 ,P <0 0 5 ,而与组织类型和临床分期均无关 ,P >0 0 5。三者在卵巢癌组织中存在共同表达。结论 :卵巢癌存在原发性耐药并涉及多个耐药基因的共同表达。联合检测对前瞻性预测化疗药物敏感性和判断化疗疗效具有指导意义     

P-glycoprotein,multidrug resistance and tumor progression

P-glycoprotein (Pgp) is a plasma membrane protein that was first characterised in multidrug resistant cell lines. The occurrence of Pgp in clinical tumors has been widely studied. Recent investigations have begun to focus on the relationship between Pgp detection in tumors and treatment outcome. In several types of tumors, detection of Pgp correlates with poor response to chemotherapy and shorter survival. P-glycoprotein overexpression often occurs upon relapse from chemotherapy but may also occur at the time of diagnosis. Studies of experimental rat liver carcinogenesis have shown that Pgp expression increases in late stages of carcinogenesis, suggesting that Pgp may be involved in tumor progression. While some of the Pgp isoforms are known to transport hydrophobic chemotherapeutic drugs out of tumor cells, the biologic effects of Pgp overexpression in tumor cells are not fully understood, because the spectrum of substrates for Pgp-mediated transport has not been determined. In the rat liver carcinoma model, strong expression of Pgp is associated with a highly vascular stroma, suggesting that Pgp in tumor cells may affect the connective tissue stroma. The regulation of Pgp appears to be complex, and little is known about how it is up-regulated during carcinogenesis. Further studies of the role of Pgp in malignancy may contribute to our understanding of molecular mechanisms which underlie tumor progression.     

Expression of multidrug resistance-1 and multidrug resistance-associated protein genes in pediatric rhabdomyosarcoma

Overexpression of multidrug resistance-1 (MDR-1), and multidrug resistance-associated protein (MRP) genes has been linked with resistance to chemotherapy in vitro and in vivo. Their role in chemotherapy resistance in pediatric rhabdomyosarcoma is unclear. The study was undertaken to analyze the expression of MDR-1 and MRP genes in the embryonal and the alveolar subtypes of rhabdomyosarcoma and to elucidate its clinical relevance. Twenty-three rhabdomyosarcoma samples were analyzed for the expression of MDR-1 and MRP genes using a semi-quantitative competitive RT-PCR assay. MRP gene expression was associated with a reduction in survival (p=0.02). The overall survival of patients with tumors positive or negative for MRP expression were 50% (95% confidence interval, 30-70%) and 93% (95% confidence interval, 76-100%) respectively. In contrast, the expression of MDR-1 gene was not predictive of survival. These findings suggest that MRP expression could be a prognostic factor in patients with rhabdomyosarcoma.     

Expression of P-glycoprotein, multidrug resistance-associated protein 1, and lung resistance-related protein in human soft tissue sarcomas before and after hyperthermic isolated limb perfusion with tumor necrosis factor-alpha and melphalan

BACKGROUND: Multidrug resistance (MDR) is associated with expression of P-glycoprotein (P-gp), multidrug resistance-associated protein 1 (MRP1), and lung resistance-related protein (LRP). Tumor necrosis factor (TNF-alpha) is able to modify the expression of these three proteins in different cell types. The effect of TNF-alpha in the clinical situation on patients with soft tissue sarcomas (STS) is indeterminate. METHODS: Thirty-seven patients with a locally advanced extremity STS underwent hyperthermic isolated limb perfusion (HILP) with TNF-alpha and melphalan; 15 patients received additional interferon gamma. Clinical and histologic responses were documented and used to define the overall response. Samples before and after HILP were analyzed immunohistochemically for P-gp, MRP1, and LRP. Samples were scored as negative or positive (< or = 5% or > 5% positive tumor cells). RESULTS: Six patients had an overall complete response, 25 patients had a partial response, and 4 patients with STS revealed no change; in 2 patients, the response remained unclear. The percentage STS samples that were positive for all three proteins dropped from 92% before HILP to 85% after HILP. P-gp positive samples were encountered more often than MRP1 positive samples (P < 0.05). The percentage of samples that were negative for all three MDR proteins increased after HILP from 6% to 16%. MDR status had no significant correlation with tumor response. CONCLUSIONS: HILP with TNF-alpha and melphalan results in excellent overall tumor response in patients with locally advanced STS. STS more often are positive for P-gp than for MRP1. MDR status in patients with STS is not predictive for tumor response after HILP. Data from the current study suggest that the combination of TNF-alpha and melphalan does not induce MDR positive STS: a result with clinical importance when consecutive, adjuvant, doxorubicin-containing chemotherapy is considered.     

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…