MDR1 P-glycoprotein is expressed by endothelial cells of newly formed capillaries in human gliomas but is not expressed in the neovasculature of other primary tumors.

The expression of human MDR1 P-glycoprotein (Pgp) in the capillary endothelial cells of the central nervous system has been demonstrated. The brain capillary endothelial cells maintain the structure and function of the blood-brain barrier. Recently, the human MDR1 Pgp (and its mouse homologue MDR1a Pgp) has been shown to function as an important part of this barrier, pumping out xenobiotics from endothelial cells into the lumen of capillaries resulting in the protection of the brain parenchyma. To examine whether the endothelial cells of the newly formed capillaries during neoangiogenesis within malignant human brain tumors express MDR1 Pgp, 35 adult surgical brain tumor specimens (29 gliomas and 6 tumors metastatic to the brain) were obtained from previously untreated patients and studied by a new immunohistochemical sandwich method developed in our laboratory using the JSB-1 monoclonal antibody. JSB-1 is specific for the Pgp product of the human MDR1 (and not MDR3) gene. This sensitive method allows the detection of Pgp in capillary endothelial cells of normal brain in conventional paraffin sections after formalin fixation. The endothelial cells of the newly formed capillaries in 25 of 29 gliomas (86%) and 3 of 6 metastatic tumors, immunostained positive for MDR1 Pgp. The tumor cells in 7 of 35 cases were also positive for Pgp. In the 35 brain tumor cases investigated, the endothelial cells were Pgp positive in the tumor-brain border and in the brain further from the tumor. Capillary endothelial cells of neovasculature in 137 malignant tumors (non-brain) obtained from previously untreated patients showed no MDR1 Pgp expression. These results demonstrated that MDR1 Pgp is expressed not only in the capillaries of normal brain but also in the majority of the newly formed capillaries of brain tumors. Multidrug resistance of brain tumors may result not only from the expression of resistance markers in neoplastic cells but also from the MDR1 Pgp expression in endothelial cells of tumor capillaries. Pgp in this special localization can exclude chemotherapeutic agents from tumor cells that are located around the capillaries. The therapeutic benefit and selectivity of chemotherapeutic agents in combination with a Pgp-reversing agent should be evaluated.     

Prognostic significance of multidrug resistance gene 1 (MDR1), multidrug resistance-related protein (MRP) and lung resistance protein (LRP) mRNA expression in acute leukemia

The prognostic significance of multidrug resistance (MDR) gene expression is controversial. We investigated whether multidrug resistance gene 1 (MDR1), multidrug resistance-related protein (MRP) and lung resistance protein (LRP) mRNA expression are associated with outcomes in acute leukemia patients. At diagnosis we examined MDR1, MRP and LRP mRNA expression in bone marrow samples from 71 acute leukemia patients (39 myeloid, 32 lymphoblastic) using nested RT-PCR. The expression of each of these genes was then expressed as a ratio in relation to beta-actin gene expression, and the three genes were categorized as being either 0, 1+, 2+ or 3+. MDR1, MRP and LRP mRNA expression was detected in 23.9%, 83.1% and 45.1 %, respectively. LRP mRNA expression was significantly associated with resistance to induction chemotherapy in acute leukemia patients, and in the AML proportion (p=0.02 and p=0.03, respectively). MRP and high MDR1 mRNA expression was associated with poorer 2-yr survival (p=0.049 and p=0.04, respectively). Patients expressing both MRP and LRP mRNA had poorer outcomes and had worse 2-yr survival. The present data suggest that MDR expression affects complete remission and survival rates in acute leukemia patients. Thus, determination of MDR gene expression at diagnosis appears likely to provide useful prognostic information for acute leukemia patients.     

Restoration of chemosensitivity in cancer cells with MDR phenotype by deoxyribozyme,compared with ribozyme

One of the main mechanisms for multidrug resistance (MDR) involves multidrug resistance gene 1 (MDR1) which encodes P-glycoprotein (Pgp). Pgp acts as a drug efflux pump and exports chemotherapeutic agents from cancer cells. Specific inhibition of Pgp expression by gene therapy is considered a well-respective strategy having less innate toxicities. At present, the investigation of DRz in reversal MDR is scarce. In the study, phosphorothioate DRz that targets to the translation initiation codon AUG was synthesized and transfected into breast cancer cells and leukemia cells with MDR phenotype. ASODN (antisense oligonucleotide) and ribozyme targets to the same region were also synthesized for comparison analysis. Alterations in MDR1 mRNA and Pgp were determined by RT-PCR, Northern blot, flow cytometry and Rh123 retention tests. Chemosensitivity of the treated cells was determined by MTT assay. The results showed that DRz could significantly suppress expression of MDR1 mRNA and inhibit synthesis of Pgp. The efflux activity of Pgp was inhibited accordingly. Chemosensitivity assay showed that a 21-fold reduction in drug resistance for Adriamycin and a 45-fold reduction in drug resistance for Vinblastine were found in the treated cells 36 h after transfection. These data suggest that DRz targeted to the translation initiation codon AUG can reverse MDR phenotype in cancer cells and restore their chemosensitivity. Moreover, the reversal efficiency of DRz is better than that of ribozyme and ASODN targets to the same region of MDR1 mRNA.     

人骨肉瘤耐阿霉素细胞模型的建立及其生物学特性

背景：多药耐药是骨肉瘤化疗失败的重要原因,目前其耐药机制不明。 目的：诱导建立耐阿霉素的人骨肉瘤细胞株并观察多药耐药蛋白1、多药耐药相关蛋白1和肺耐药蛋白的表达。 方法：采用逐步递增阿霉素浓度间歇作用的方法诱导143B/WT细胞株建立143B/阿霉素耐药细胞株。 结果与结论：经阿霉素诱导45 d建立了143B/阿霉素细胞株,其对阿霉素高度耐药,对顺铂、甲氨蝶呤、异环磷酰胺、长春新碱和紫杉醇亦产生不同程度交叉耐药;流式细胞仪检测显示与143B野生型细胞相比,143B/阿霉素细胞周期中G1和S期所占比例增加,而G2/M期所占比例明显减少;罗丹明外排实验显示,143B/阿霉素细胞药物外排能力显著高于143B/WT细胞(P < 0.01);流式细胞仪和激光共聚焦显微镜观察发现,143B/阿霉素细胞阿霉素相关性细胞凋亡率显著低于143B/WT(P < 0.01);Western blot检测显示143B/阿霉素细胞多药耐药蛋白1表达水平较143B/WT显著升高(P < 0.01),二者多药耐药相关蛋白1和肺耐药蛋白表达差异无显著性意义(P > 0.05)。提示143B/阿霉素细胞多药耐药的产生与多药耐药蛋白1表达升高相关。     

恶性肿瘤细胞多药耐药基因(MDR1)表达产物P170的流式细胞学的检测

目的，探讨用流式细胞免疫学检测恶性实体瘤组织及腹水细胞多药耐药基因（ＭＤＲ１）表达的方法和临床意义。方法：采用搓网方法，将１２种９４例不同的恶性肿瘤手术切除标本制成细胞膜完整的单细胞悬液，并从６例癌性腹水中提取富含癌细胞的悬液，再用流式细胞免疫学方法检测悬液中癌细胞ＭＤＲ１表达产物Ｐ１７０含量。结果：经所用方法制备悬液中的癌细胞丰富，杂质细胞少，荧光显微镜下观察细胞膜完整，Ｐ１７０阳性细胞抗体荧光位于细胞膜上。结论：研究恶性实体肿瘤细胞ＭＤＲ１表达是可行的，可明确其原始的药物敏感性，对临床化疗有重要价值     

反义寡聚脱氧核苷酸抑制卵巢癌细胞株SKOV3／mdr1中MDR1基因的表达

多药耐药基因（MDR1）编码的P－糖蛋白(Pgp,P-170)是导致卵巢癌化疗失败的重要因素之一。本研究将针对MDR1基因的硫代反义寡聚脱氧核苷酸导入卵巢癌耐药细胞株SKOV3/mdr1,观察其对该细胞株P170表达的影响。反义寡聚脱氧核苷酸（MDR1－AS）通过阳离子脂质体介导或单纯转染的方式导入SKOV3／mdr1 细胞,将正义寡聚脱氧核苷酸（MDR1－S)同样导入细胞为对照。经以脂质体介导的1．6μmol/L MDR1-AS转染后,Pgp阳性的细胞百分数从100％降至48．7％,经过16和10μmol／L两个浓度的单纯MDR1－AS转染后,Pgp阳性细胞的百分数也从100％分别降至52．6％和86．7％。同时,利用RT－PCR检测了MDR1mRNA水平的变化,以β-actin作为内对照,发现MDR1mRNA水平在MDR1－AS转染后降至内对照的60％左右,而用MDR1－S转染的细胞与SKOV3／mdr1细胞比无明显变化。所以导入MDR1基因硫代反义寡聚脱氧核苷酸可以部分抑制SKOV3／mdr1细胞中MDR1基因的表达。     

Interferon-gamma up-regulates expression and activity of P-glycoprotein in human peripheral blood monocyte-derived macrophages.

P-glycoprotein (Pgp), the product of the multidrug resistance (MDR1) gene, is expressed in a variety of normal tissues but very little is known about its expression and function in cells of the immune system. In this study, we investigated the effect of interferon-gamma (IFN-gamma) on the expression and activity of Pgp in human peripheral blood monocyte-derived macrophages (MDM). We report that IFN-gamma up-regulated Pgp expression in a dose- and time-dependent manner. We show that IFN-gamma slightly increased the accumulation of MDR1 mRNA and induced a polarized redistribution of Pgp, as well as of some cytoskeletal proteins (ie, ezrin, actin, and alpha-actinin) on cell pseudopodia. Notably, confocal microscopy studies showed that Pgp and ezrin colocalized in these cellular structures. The IFN-gamma-induced Pgp up-modulation was a specific response of primary macrophages, as IFN-gamma treatment of primary lymphocytes and monocytic cell lines did not result in any increase of Pgp expression. Finally, IFN-gamma stimulated the Pgp transport activity in MDM, as rhodamine 123-efflux increased in treated cells as compared with control cultures. These results indicate that Pgp expression and activity can be up-regulated in human MDM in response to IFN-gamma. We suggest that IFN-gamma may be involved in the induction of multidrug resistance in macrophages.     

细胞因子诱导杀伤细胞转MDR1基因诱导耐药研究

目的细胞因子诱导杀伤细胞(cytokine-induced-killer,CIK)进行临床免疫治疗能够杀伤肿瘤细胞,将MDR1基因转入CIK细胞,观察其是否产生耐药性并且保持其肿瘤杀伤活性.方法用Ficoll密度梯度离心法获得外周血单个核细胞,分别加入IFN-γ,CD3Mab,IL-2,IL-1等细胞因子体外培养获得CIK细胞.在细胞呈对数生长期时,采用电穿孔方法将多药耐药基因PHAMDR质粒转入细胞.转染后72h提取细胞总RNA,RT-PCR鉴定耐药基因表达;流式细胞仪方法检测细胞膜泵蛋白P-gp.四唑蓝比色法(MTT Assay)检测转基因CIK细胞对阿霉素和秋水仙碱的耐药性,同时检测转染前后CIK细胞对人类乳腺癌细胞系(MCF7)的杀伤活性变化.结果转染后CIK细胞出现MDR1基因的转录产物mR-NA;流式细胞仪检测,转染后的CIK细胞表达耐药蛋白P-gp,阳性细胞约为21%.阿霉素对转染后CIK细胞的IC50为0.11mg/ml,转染后CIK细胞对阿霉素的耐受性较转染前CIK细胞(IC50为0.0024mg/ml)增强了45.8倍;秋水仙碱对转染后CIK细胞的IC50为1.34ng/ml,转染后耐受性较转染前CIK细胞增强了11.35倍(IC50为0.118ng/ml).比较转染前后CIK细胞对MCF7肿瘤细胞的杀伤活性无显著性差异(P＞0.05).结论用电穿孔方法可以成功地将MDR1基因转入CIK细胞,并使其表现出多药耐药性,转染前后细胞杀伤活性无变化.     

Concomitance of P-gp/LRP Expression with EGFR Mutations in Exons 19 and 21 in Non-Small Cell Lung Cancers

Purpose

Traditional chemotherapy is the main adjuvant therapy for the treatment of non-small cell lung cancer (NSCLC). However, the emergence of multi-drug resistance (MDR) has greatly restricted the curative effect of chemotherapy. Therefore, it is necessary to find a method to treat MDR NSCLC clinically. It is worth investigating whether NSCLCs that are resistant to traditional chemotherapy can be effectively treated with tyrosine kinase inhibitors targeting epidermal growth factor receptor (EGFR).

Materials and Methods

The expression of P-glycoprotein (P-gp) and lung resistance-related protein (LRP) was detected by immunohistochemistry, and mutations in EGFR (exons 19 and 21) and Kirsten rat sarcoma viral oncogene homolog (KRAS) (exon 2) were detected by high-resolution melting analysis (HRMA) of surgical NSCLC specimens from 127 patients who did not undergo traditional chemotherapy or radiotherapy. A Pearson chi-square test was performed to analyze the correlations between the expression of P-gp and LRP and mutations in EGFR and KRAS.

Results

The expression frequencies of P-gp and LRP were significantly higher in adenocarcinomas from non-smoking patients; the expression frequency of LRP was significantly higher in cancer tissue from female patients. The frequency of EGFR mutations was significantly higher in well to moderately differentiated adenocarcinomas from non-smoking female patients. The frequency of EGFR mutations in the cancers that expressed P-gp, LRP, or both P-gp and LRP was significantly higher than that in cancers that did not express P-gp or LRP.

Conclusion

NSCLCs expressing P-gp/LRP bear the EGFR mutation in exon 19 or 21 easily.     

Broad distribution of the multidrug resistance-related vault lung resistance protein in normal human tissues and tumors.

Multidrug resistance (MDR) to anticancer drugs is a major cause of treatment failure in cancer. The lung resistance protein LRP is a newly described protein related to MDR in several in vitro models. LRP has been shown to be a strong predictor of poor response to chemotherapy and prognosis in acute myeloid leukemia and in ovarian carcinoma patients. Recently, based on a 57% and 88% amino acid identity with major vault proteins from Dictyostelium discoideum and Rattus norvegicus, respectively, we identified LRP as the human major vault protein, the main component of highly conserved cellular organelles named vaults. We have studied the immunohistochemical expression of LRP in freshly frozen normal human tissues and 174 cancer specimens of 28 tumor types. LRP was broadly distributed in normal and malignant cells, but distinct patterns of expression were noticed. High LRP expression was seen in bronchus, digestive tract, renal proximal tubules, keratinocytes, macrophages, and adrenal cortex whereas varying ing levels were observed in other organs. LRP was detected in all tumor types examined, but its frequency varied, fairly reflecting the chemosensitivity of different cancers. For example, low rates of LRP positivity were seen in testicular cancer, neuroblastoma, and acute myeloid leukemia; intermediate in ovarian cancer; and high in colon, renal, and pancreatic carcinomas. The wide occurrence of LRP in normal and transformed cells in humans, its similar distribution to that of vaults in other species, as well as the high level of conservation among eukaryotic cells of both the amino acid sequence of the major vault protein and the composition and structure of vaults, suggest that vault function is important to eukaryotic cells.     

Expression dynamics of drug resistance genes, multidrug resistance 1 (MDR1) and lung resistance protein (LRP) during the evolution of overt leukemia in myelodysplastic syndromes

It is well-known that leukemic cells of overt leukemia (OL) that have transformed from myelodysplastic syndromes (MDS) are more resistant to chemotherapy as compared with de novo AML cells. Thus, to examine the expression levels of drug-resistant genes and their alterations with the development of OL in MDS, the expression of mRNA for MDR1 and LRP was determined in bone marrow samples from control, de novo AML, MDS, MDS at the time of OL transformation (MDS --> OL), and after transformation (OL) by quantitative real-time RT-PCR. The expression of MDR1 in MDS bone marrow at the time of initial diagnosis was as low as that for control subjects. However, the expression level was significantly elevated at the time of the development of OL (MDS --> OL) compared with the initial MDS subjects (P < 0.05), while expression was relatively reduced after OL development (OL). The expression of LRP was significantly higher in MDS and MDS --> OL samples than control subjects. However, the high expression of LRP in MDS --> OL was significantly reduced after OL development (OL). The expression levels of drug-resistant genes in MDS --> OL or OL were not significantly higher than those of de novo AML samples, although LRP expression in MDS or MDS --> OL was relatively higher than that of de novo AML. Detecting increases in the expression of MDR1 would be useful for predicting OL development in MDS patients.     

原发性肝癌粘附分子基因的表达与化疗敏感的相关性研究

目的：探讨原发性肝癌粘附因子基因的表达与化疗敏感的相关性。方法： 取64例肝癌切除组织行ATP-TCA法肿瘤体外药敏试验，以RT-PCR法半定量检测肝癌多种粘附因子、多药耐药基因表达情况。 结果： 肝癌组织E-cadherin, ICAM-1, CD44, CD44V, α5,β1基因mRNA的表达量分别为1.24±0.54, 0.96±0.37, 0.62±0.73, 0.86±0.33, 0.97±0.49, 1.41±0.24，其中CD44与E-cadherin、β1的表达量有显著差异。多药耐药基因MDR1、MRP、GST-π、LRP、TOPOⅡ的表达量分别为1.17±0.47、1.59±0.33、1.18±0.48、1.03±0.48、1.00±0.31。各粘附分子基因的表达与多药耐药基因的表达有一定的相关性：其中ICAM-1、α5的表达与MDR1的表达呈正相关，E-cadherin、CD44的表达与MDR1的表达呈负相关； E-cadherin的表达与MRP的表达呈负相关；ICAM-1的表达与LRP的表达呈正相关，E-钙粘连素、CD44的表达与LRP的表达呈负相关。肝癌化疗疗效与粘附分子基因mRNA表达量的关系：在化疗有效组E-cadherin、CD44的mRNA表达量高于无效组，ICAM-1、CD44V、α5、β1的mRNA表达量低于无效组。两组差别无显著意义。结论： 在肝癌部分粘附分子的基因mRNA的表达与部分多药耐药基因mRNA的表达相关，与化疗的疗效有关。     

Increased expression of multidrug resistance related proteins Pgp, MRP1, and LRP/MVP occurs early in colorectal carcinogenesis

AIM: To analyse the expression of multidrug resistance (MDR) related proteins at different steps in colorectal carcinogenesis. METHODS: The presence of three MDR related proteins (Pgp, MRP1, and LRP/MVP) was studied by means of immunohistochemistry in normal, adenomatous, and malignant colorectal epithelium. Formaldehyde fixed, paraffin embedded tissue sections of 17 samples of colorectal tissue were used (normal mucosa, n = 4; adjacent mucosa, n = 5; adenoma, n = 5; carcinoma, n = 3). RESULTS: For all three proteins, expression was found in the surface epithelium and the upper parts of the crypts in normal colon. In the adenomas, staining was seen along the complete length of the crypts. In the carcinomas analysed, all epithelium showed positive staining. Mucosa adjacent to either carcinoma or adenoma showed staining patterns mostly resembling those of normal mucosa, but sometimes some extension of staining was seen along the crypt. CONCLUSIONS: These proteins already show increased expression in the adenoma stage. In the absence of adequate mucin production in adenomas, MDR related proteins could be an important factor in protecting the epithelium against further environmentally induced genetic damage. This could be one of the reasons why only about 5% of colorectal adenomas will actually progress to carcinomas.     

PIK3CA and PIK3CB expression and relationship with multidrug resistance in colorectal carcinoma

The phosphoinositide 3-kinases (PI3Ks) are a critical family of signaling enzymes that participate in many cellular processes that promote the transformation of a normal cell into a cancer cell. These processes include cancer cell proliferation, migration, and invasion. However, the correlation between PI3Ks and multidrug resistance (MDR) remains unclear. The prognostic value of PI3Ks has not been previously evaluated. Thus, this study aims to evaluate the association between PIK3CA and PIK3CB expression and the MDR gene in colorectal cancer (CRC) patients. Immunohistochemistry was employed to detect the expressions of PIK3CA, PIK3CB, MDR-1, LRP, GST-π, and Topo II in 316 CRC specimens. Patients were followed-up annually by telephone or at an outpatient clinic. Results revealed that PIK3CA and PIK3CB expression was correlated with the degree of tumor differentiation and lymph node metastasis (P < 0.05). The overexpression of MDR-1, LRP, Topo II, and GST-π was found to be 72.78%, 70.89%, 77.53%, and 76.58% of CRC, respectively. Correlation analysis showed that PIK3CA and PIK3CB expression exhibits a positive correlation with MDR-1, LRP, and GST-π with correlation coefficients of 0.288, 0.128, and 0.197, respectively (P < 0.05). Kaplan-Meier analysis revealed that the five-year survival rate of patients without lymph node metastasis, positive expression of PIK3CA and PIK3CB, and negative expression of GST-π and MDR-1 was higher than those with these characteristics. Multivariate analysis revealed that GST-π, MDR-1 expression, and lymph node metastasis could serve as independent predictive factors of overall survival. The expression of both PIK3CA and PIK3CB is increased and related to the development and progress of colorectal carcinoma and MDR. The combined detection of PIK3CA andPIK3CB is important for patients with colorectal carcinoma in prognosis and optimal therapy.     

长春新碱降低由转染A20 siRNA促进的弥漫大B细胞淋巴瘤细胞系增殖

目的研究A20小分子干扰RNA片段(siRNA)对弥漫大B细胞淋巴瘤细胞(OCI-LY1)增殖和多药耐药基因(MDR1)表达的影响。方法分对照组、转染组、长春新碱干预组(VCR)组和转染+VCR组。用脂质体转染法将A20 siRNA转入OCI-LY1细胞,MTT法检测细胞对VCR的敏感性;流式细胞计量术检测细胞凋亡;用real-time PCR检测A20及MDR1 mRNA;用Western blot检测细胞内A20、Pgp蛋白及核蛋白NF-κB的表达。结果 1)A20 siRNA转染后,细胞增殖能力增强(P0.05),VCR刺激后转染细胞的增殖曲线下降缓慢。2)转染细胞凋亡率明显低于对照组,VCR刺激24 h后OCI-LY1细胞凋亡率较加药前明显增加(P0.05),VCR组凋亡率比转染+VCR组增高的幅度大(P0.05)。3)转染后,A20 mRNA及蛋白表达明显降低(P0.001),NF-κB蛋白(P0.001)、MDR1mRNA(P0.001)和Pgp(P0.001)表达都明显增高;但MDR1 mRNA和Pgp在药物刺激后表达降低(P0.05),且VCR组较转染+VCR组降低的幅度大(P0.01)。结论 A20 siRNA能有效的增强OCI-LY1细胞内NF-κB的表达,使得MDR1基因及编码蛋白Pgp蛋白增强,从而抑制细胞凋亡、促进细胞增殖;VCR刺激后细胞内MDR1 mRNA和Pgp的表达明显降低,A20 siRNA则减弱了VCR的这一作用。     

Expression of genes related to multiple drug resistance and apoptosis in acute leukemia: response to induction chemotherapy

Resistance to chemotherapy is a major impediment to the successful treatment of acute leukemia (AL). Expression of genes involved in drug resistance and apoptosis may be responsible for this. This study aimed to investigate the expression of drug resistance (MDR1, MRP1, LRP, BCRP, GSTP1, DHFR) and apoptotic genes (p53, BCL-2, Survivin) in adult acute leukemias and compare them with clinical and hematological findings and response to induction chemotherapy. Eighty-five patients with AL [45 with acute myeloid leukemia (AML) and 40 with acute lymphoblastic leukemia (ALL)] were used as a study group. Real-time PCR results showed that expression level of MDR1 was significantly higher in AML whereas expression of DHFR, BCRP and Survivin was significantly higher in ALL patients. In AML, significant correlation was observed between LRP and MRP1 (r(s)=0.44, p=0.016), LRP and DHFR (r(s)=0.41, p=0.02), MDR1 and BCL-2 (r(s)=0.38, p=0.03). Expression of GSTP1 and LRP correlated with high white blood count (p=0.03 and p=0.03) and BCL-2 with high peripheral blast count (p=0.009). MDR1 expression was significantly associated with the expression of immature stem cell marker CD34 (p=0.002). In ALL, significant association was found between LRP gene and female sex (p<0.0001), LRP and B-ALL patients (p=0.04) and LRP and BCR/ABL positive patients (p=0.004). High expression of MDR1 and BCL-2 in AML and MRP1 gene in ALL was associated with response to induction chemotherapy (p=0.001, p=0.02 and p=0.007 respectively). These results showed the potential clinical relevance of MDR1, MRP1 and BCL-2 in adult patients with acute leukemia in the context of induction chemotherapy.