肿瘤多药耐药机制及逆转耐药研究进展北大核心

癌症化学治疗被视为旨在最小化和延迟肿瘤的发生、发展或复发的策略,但是肿瘤多药耐药是肿瘤患者治疗失败和复发的主要原因,是实现肿瘤患者治愈的主要限制因素。如何逆转化疗药物的耐药及耐药机制的研究成为肿瘤研究的挑战。为了解决肿瘤多药耐药问题,本文对传统化疗药物发生肿瘤多药耐药的机制、靶向治疗发生多药耐药的机制以及免疫治疗发生多药耐药的机制进行阐述;确定了癌症耐药性的实验室方法,如MTT测试法、药物敏感性测试、多药耐药基因和途径检测、高通量筛选技术、基因芯片技术等,为多药耐药的研究提供实验方法;并对多药耐药抑制剂或逆转剂的研究进展进行简单的综述,旨在为进一步发明逆转肿瘤多药耐药的药物提供研究基础。     

肿瘤多药耐药的研究进展

化疗是目前治疗肿瘤最有力、最常用的手段，而在治疗过程中产生的多药耐药（multidrug resistance，MDR）现象却是造成失败的主要因素。多药耐药是指当一种药物作用于肿瘤细胞使之产生耐受性后，该肿瘤对未接触过的、结构无关、机制不同的肿瘤药物也具有耐受性，产生交叉耐药。为此，对多药耐药的研究成为肿瘤领域的研究热点。现结合文献将多药耐药研究现状综述如下。     

肿瘤多药耐药机制及其逆转方案的研究进展

肿瘤多药耐药是临床上肿瘤化疗失败的主要原因。近年来,有关肿瘤多药耐药的机制研究及寻找低毒高效的肿瘤耐药逆转剂已成为肿瘤化学药物治疗领域的新热点。作者对肿瘤多药耐药机制的可能途径及其逆转方案的最新研究进行了综述,为今后的相关研究和临床应用提供参考。     

肿瘤多药耐药机制的研究进展

肿瘤多药耐药已成为肿瘤化疗成功与否的关键因素之一,因此克服肿瘤多药耐药是肿瘤治疗的当务之急。肿瘤多药耐药机制是一个十分复杂的过程,受多种因素影响。因此,对肿瘤多药耐药机制进行深入研究将有助于筛选出更加合适的抗肿瘤药物。本文就近年来肿瘤多药耐药机制的研究进展做一综述。     

ATP-binding cassette家族和肿瘤干细胞的多药耐药

肿瘤细胞的多药耐药是临床化疗失败的常见原因，通常表现为肿瘤细胞对一系列作用机制各异的抗癌药物失去敏感性。对肿瘤细胞多药耐药的研究已经发现ATP—binding cassette转运蛋白家族外排药物和细胞耐药机制之间存在直接关系，有些正在开发中的针对耐药蛋白的药物已经显示了应用的前景。肿瘤干细胞是肿瘤中存在的极小的一群具有类似干细胞性质的肿瘤细胞，是肿瘤发生发展的内在动力。最近的研究发现肿瘤干细胞表面也表达ATP—binding cassette家族多药耐药蛋白，揭示了肿瘤的起源和耐药现象的联系。     

肿瘤耐药逆转剂研究新进展

肿瘤耐药逆转剂研究新进展陆东东肿瘤细胞对多种化疗药物产生交叉抗药性是造成肿瘤化疗失败的主要原因。多药耐药（ＭＤＲ）的发生机制十分复杂，其中多药耐药基因编码的Ｐ－糖蛋白（ＰｇＰ）高表达是多药耐药的主要机制。人类ｍｄｒ１基因编码的ＰｇＰ是一种能量依赖性“...     

肺耐药相关蛋白和卵巢恶性肿瘤

化学药物治疗是妇科恶性肿瘤治疗的主要方法，并起着越来越重要的作用，但各种化疗都面临着耐药问题。耐药发生的机制复杂，相关因素也较多，研究较多的有多药耐药基因-1(MDR 1基因)及P-糖蛋白(P170蛋白)。多药耐药蛋白基因(MRP基因)及多药耐药蛋白(MRP蛋白)，这两种蛋白同属膜转运蛋白超家族成员，具有药泵功能，能将化疗药物(蒽环类、生物碱、表鬼臼毒类)泵出肿瘤细胞外，从……     

survivin基因与肿瘤多药耐药

肿瘤多药耐药是多种复杂机制共同作用的结果。大量研究表明survivin基因参与了细胞凋亡和细胞有丝分裂的调控,与肿瘤多耐药密切相关。     

高通量分析技术在肿瘤MDR中的研究进展

高通量分析技术是近年来肿瘤研究新平台，肿瘤多药耐药（MDR）和耐药逆转药物研究在肿瘤化疗领域亟需解决。现综述基因芯片、蛋白质芯片、组织芯片三大高通量微阵列技术在肿瘤MDR机制、筛选耐药逆转靶点和逆转药物及指导临床个体化治疗等方面的应用。     

肿瘤多药耐药机制及其应对策略的研究进展

多药耐药现象是当前临床肿瘤治疗的主要障碍，且尚无有效的逆转方案。经过长期探索发现，细胞内药物外排增加、代谢增强、吸收下降、DNA突变及修复功能增强、肿瘤微环境影响等多种机制均参与了多药耐药现象的发生，且这些机制受转录因子、miRNA 及lncRNA 等因素的调控。当前研究者已开发出多种应对策略，包括小分子、中药逆转剂、纳米载体及生物疗法等进行耐药肿瘤治疗，但其疗效和生物安全性仍有待于进一步提升，深入的机制探索和多模态的治疗方案开发将是未来多药耐药肿瘤治疗的重要发展方向。     

Knockdown of MDR1 Increases the Sensitivity to Adriamycin in Drug Resistant Gastric Cancer Cells

Gastric cancer is one of the most frequently occurring malignancies in the world. Development of multipledrug resistance (MDR) to chemotherapy is known as the major cause of treatment failure for gastric cancer.Multiple drug resistance 1/P-glycoprotein (MDR1/p-gp) contributes to drug resistance via ATP-dependent drugefflux pumps and is overexpressed in many solid tumors including gastric cancer. To investigate the role of MDR1knockdown on drug resistance reversal, we knocked down MDR1 expression using shRNA in drug resistantgastric cancer cells and examined the consequences with regard to adriamycin (ADR) accumulation and drugsensitivity.Two shRNAs efficiently inhibited mRNA and protein expression of MDR1 in SGC7901-MDR1 cells.MDR1 knockdown obviously decreased the ADR accumulation in cells and increased the sensitivity to ADRtreatment. Together, our results revealed a crucial role of MDR1 in drug resistance and confirmed that MDR1knockdown could reverse this phenotype in gastric cancer cells.     

Multidrug resistance in human cancer

Resistance to cytotoxic chemotherapy continues to be a major obstacle to more effective treatment of human cancers. A particular problem in clinical cancer chemotherapy is the phenomenon of simultaneous resistance of cancers to a variety of unrelated cytotoxic agents. Such resistance to multiple drugs is observed much more often than resistance to individual compounds. A similar experimental phenomenon has been termed multidrug resistance or MDR. Much has been learned in recent years about molecular mechanisms which can lead to MDR in cancer cells and a number of studies has been performed to evaluate the clinical relevance of such mechanisms. In particular, P-glycoprotein-associated MDR (MDR1) has received a lot of attention. This review will discuss (i) some principal aspects of drug resistance in cancer with particular emphasis on MDR1; (ii) available data on drug resistance mechanisms in brain tumors; and (iii) our current knowledge on the putative role of P-glycoprotein in the blood-brain barrier.     

Synergistic effect of cyclosporin A and verapamil in overcoming vincristine resistance of multidrug-resistant cultured human leukemia cells

Reversal of vincristine (VCR) resistance by cyclosporin A (CyA) or the combination of CyA and verapamil (VER) was investigated by using four P-glycoprotein (P-gp)-associated human multidrug-resistant (MDR) cell lines (K562/ADM, KYO-1, HEL and CMK). Drug sensitivity was expressed as 50% inhibitory concentration (IC50). The degree of reversal of resistance was expressed as x-fold decrease by dividing the IC50 value without modifier(s) by that with modifier(s). CyA overcame P-gp-associated MDR significantly in all four MDR cell lines. Reversal of VCR resistance by CyA appeared to be dose-dependent. In the case of low-grade MDR cell lines (KYO-1, HEL and CMK), CyA at the low concentration of 0.5 microgram/ml was still effective. The degree of reversal of VCR resistance in this condition was greater (6.3- to 16-fold decrease) in the low-grade MDR cell lines than in a high-grade MDR cell line (K562/ADM) (2.9-fold decrease). At a high concentration (5 micrograms/ml) of CyA, however, it was greater (240-fold decrease) in the high-grade MDR cell lines than in the low-grade MDR cell line (20- to 100-fold decrease). This indicates that concentration of CyA required for overcoming drug resistance in MDR cells was dependent on the degree of drug resistance. CyA overcame VCR resistance more efficiently than VER. The combination of CyA and VER enhanced reversal of VCR resistance in a supra-additive or at least an additive manner and overcame VCR resistance at low concentrations of both modifiers that are clinically achievable with safety.     

Synergistic Effect of Cyclosporin A and Verapamil in Overcoming Vincristine Resistance of Multidrug-resistant Cultured Human Leukemia Cells

Reversal of vincristine (VCR) resistance by cyclosporin A (CyA) or the combination of CyA and verapamil (VER) was investigated by using four P-glycoprotein (P-gp)-associated human multidrug-resistant (MDR) cell lines (K562/ADM, KYO-1, HEL and CMK). Drug sensitivity was expressed as 50% inhibitory concentration (IC₅₀). The degree of reversal of resistance was expressed as x -fold decrease by dividing the IC₅₀ value without modifier(s) by that with modifier(s). CyA overcame P-gp-associated MDR significantly in all four MDR cell lines. Reversal of VCR resistance by CyA appeared to be dose-dependent. In the case of low-grade MDR cell lines (KYO-1, HEL and CMK), CyA at the low concentration of 0.5 μg/ml was still effective. The degree of reversal of VCR resistance in this condition was greater (6.3- to 16-fold decrease) in the low-grade MDR cell lines than in a high-grade MDR cell line (K562/ADM) (2.9-fold decrease). At a high concentration (5 μg/ml) of CyA, however, it was greater (240-fold decrease) in the high-grade MDR cell lines than in the low-grade MDR cell line (20- to 100-fold decrease). This indicates that concentration of CyA required for overcoming drug resistance in MDR cells was dependent on the degree of drug resistance. CyA overcame VCR resistance more efficiently than VER. The combination of CyA and VER enhanced reversal of VCR resistance in a supra-additive or at least an additive manner and overcame VCR resistance at low concentrations of both modifiers that are clinically achievable with safety.     

Establishment and characterization of new cellular lymphoma model expressing transgenic human MDR1

Multidrug resistance (MDR) due to the expression of the MDR1 gene and its P-glycoprotein (Pgp) product is a major factor in the prognosis and clinical outcome of patients with refractory lymphomas and other malignancies. The aim of our study was to establish a lymphoma, cellular system where a de novo acquisition of multidrug resistance is specifically related to overexpression of a transgenic, human MDR1. A multidrug sensitive lymphoma cell line (LM1) was established from a sporadic T-cell lymphoma of BALB/c mouse and was transduced by a retroviral vector containing the human MDR1 cDNA. The resultant cell variant (LM1/MDR) was characterized in comparison to the parental LM1 cells. The LM1/MDR cell variant is cross-resistant to DOX, COL, ACT D and VBL. This cell variant expresses the human MDR1 and exhibits de novo functional Pgp activity that can be blocked by the Pgp-modulators VRP and KT-5720. The acquired MDR of LM1/MDR is not accompanied with gene amplification, alternative splicing or up-regulation of the murine endogenous mdr1a, mdr1b, mrp1, mrp2 and mrp3 transporter-genes. Therefore, the acquired MDR is, specifically, human MDR1-dependent as it has been found in malignant cells of most lymphoma patients. Moreover, this system can be used as a model to study MDR and the efficacy of drugs and modulators on malignant cells where human Pgp is a major factor of multidrug resistance.     

外源MDR-1基因对小鼠肺腺癌细胞耐药性产生的影响及机理研究

目的 了解ＭＤＲ－１基因表达中细胞药性的关系。方法 用ＦＵＧＥＮ＾ＴＭ６转染试剂将ＭＤＲ－１基因导入小鼠Ｌｅｗｉｓ肺腺癌细胞株（３ＬＬ）,建立池耐药细胞株（３ＬＬ－ＭＤＲ－１）．用ＭＴＴ方法测定和划搏定对药的逆转效应,ＭＤＲ－１基因表达产物ｐ－ｇｐ采用免疫组化方法观察,应用流式细胞仪分析其对示踪剂罗丹明１２３的摄取与排泄。结果 建立了一株能稳定表达ｐ－ｇｐ和对长春生物碱类、鬼白纱类具有显著耐药性的     

Impact of BCRP/MXR, MRP1 and MDR1/P-Glycoprotein on thermoresistant variants of atypical and classical multidrug resistant cancer cells

The impact of the ABC transporters breast cancer resistance protein/mitoxantrone resistance associated transporter (BCRP/MXR), multidrug resistance-associated protein 1 (MRP1) and multidrug resistance gene-1/P-glycoprotein (MDR1/PGP) on the multidrug resistance (MDR) phenotype in chemoresistance and thermoresistance was investigated in the parental human gastric carcinoma cell line EPG85-257P, the atypical MDR subline EPG85-257RNOV, the classical MDR subline EPG85-257RDB and their thermoresistant counterparts EPG85-257P-TR, EPG85-257RNOV-TR and EPG85-257RDB-TR. Within the atypical MDR subline EPG85-257RNOV expression of BCRP/MXR and of MRP1 were clearly enhanced (vs. parental and classical MDR lines). MDR1/PGP expression was distinctly elevated in the classical MDR subline EPG85-257RDB (vs. parental and atypical MDR sublines). In all thermoresistant counterparts basal expression of BCRP/MXR, MRP1 and MDR1/PGP was increased relative to thermosensitive sublines. Although it could be shown that the overexpressed ABC transporters were functionally active, however, no decreased drug accumulations of doxorubicin, mitoxantrone and rhodamine 123 were observed. Thus, expression of BCRP/MXR, MRP1 and MDR1/PGP was found to be dependent on the appropriate type of chemoresistance; correlating with a classical or atypical MDR phenotype. Within the thermoresistant variants, however, the increase in ABC transporter expression did obviously not influence the MDR phenotype.     

Compounds from Chinese herbal medicines as reversal agents for P-glycoprotein-mediated multidrug resistance in tumours

Multidrug resistance (MDR) is a major obstacle to successful cancer chemotherapy. One of the main underlying mechanisms of this resistance is the over-expression of P-glycoprotein (P-gp), an ATP-dependent transmembrane transporter protein encoded by the MDR1 gene. P-gp might transport anti-cancer drugs out of cancer cells and decrease effective intracellular drug concentrations. An effective approach to overcome MDR is to inhibit the function of P-gp or its expression on the surface of cancer cells. Thus, application of MDR reversal agents can be seen as a potentially important means by which to overcome the clinical drug resistance of tumour cells and improve the efficacy of chemotherapy. Recently, research efforts worldwide have focused on reversal mechanisms for MDR and on the identification of reversal agents. Chinese scholars have performed a great deal of exploratory work by screening for efficacy and low toxicity in drug resistance reversal compounds. These compounds may provide more lead compounds with greater activity, leading to the development of more effective therapies for MDR cancer cells. In this review, the function and efficiency of novel compounds derived from traditional Chinese medicines are described.     

Clinical correlates of MDR1 (P-glycoprotein) gene expression in ovarian and small-cell lung carcinomas.

BACKGROUND: Expression of the MDR1 (P-glycoprotein) gene causes resistance to several classes of lipophilic anti-cancer drugs, but MDR1 expression in untreated ovarian and lung carcinomas is rarely detectable by standard assays. PURPOSE: This study was designed to measure the MDR1 messenger RNA (mRNA) content of ovarian and lung carcinomas and to analyze clinical correlations of MDR1 expression in these tumors. METHODS: A sensitive assay based on the polymerase chain reaction (PCR) was used in a retrospective study to measure MDR1 mRNA in biopsy samples of 100 solid tumors, including 60 ovarian and 32 lung carcinomas. The levels of MDR1 mRNA were correlated with history of chemotherapeutic treatment for all tumors; for ovarian and small-cell lung carcinomas (SCLCs), these levels were also correlated with subsequent tumor response to chemotherapy. RESULTS: Among previously untreated patients, MDR1 mRNA was expressed in 68% (50 of 74) of all tumors. Among patients pretreated with chemotherapy regimens that included at least one P-glycoprotein-transported drug (MDR regimens), 95% (20 of 21) of all tumors expressed MDR1 mRNA though the incidence of high-level MDR1 expression was decreased among the treated tumors. MDR1 mRNA was expressed in only one of five tumors treated with regimens that included no P-glycoprotein substrates (non-MDR regimens). Subsequent tumor response to chemotherapy was evaluated in 35 patients with ovarian carcinoma and seven patients with SCLC. The presence of even very low levels of MDR1 mRNA correlated with the lack of response to MDR regimens in these tumor types (P < .035 for ovarian carcinomas, P < .029 for SCLCs, and P < .0005 for both tumor types; Fisher's Exact Test). CONCLUSIONS: Low-level expression of MDR1 mRNA correlates with clinical resistance to combination chemotherapy in ovarian cancer and SCLC. We hypothesize that MDR1 is expressed in a subpopulation of more malignant tumor cells possessing multiple mechanisms of drug resistance. IMPLICATIONS: The presence of MDR1-expressing tumor cells may be useful as a predictive marker for clinical resistance to combination chemotherapy in ovarian cancer and SCLC. Prospective studies are needed to confirm this hypothesis.     

Expression of multidrug resistance (p-glycoprotein) mdr1 and mdr2 genes in human hepatocellular carcinomas and liver metastases of colonic tumors

Overexpression of P-glycoproteins (P-gp), encoded by multidrug resistance (MDR) genes is responsible for multidrug resistance in animal cells. We analyzed the expression of MDR genes in human hepatocellular carcinomas (HCC) and liver metastases of colon tumors by an RNase protection assay. Our results indicated that both genes were not consistently overexpressed in these tumors, whereas MDR2 is often underexpressed in the metastatic tumors. Invasion of colon tumors to livers decreased MDR1 expression. These data suggest differential regulation mechanisms for the expression of MDR1 and MDR2 genes in these tumors, and a complex drug-resistance mechanism for liver cancers.