Serum 27E10 antigen: a new potential marker for staging HIV disease.

MRP8 and MRP14 are myeloic related proteins expressed by most circulating and emigrated neutrophils and monocytes. Their composite molecule MRP8/14 (27E10 antigen) was shown to exhibit striking antimicrobial properties. The aim of the present study was to assess the value of MRPs as markers for detection of the different stages of HIV infection (Centres for Disease Control and Prevention, 1993). By employing the ELISA technique we measured serum concentrations of these proteins in samples from 122 HIV patients at the various stages of disease, and the results were compared with those for healthy controls. Serum levels of the heterodimeric molecule 27E10 were significantly increased (P < 0.001) in patients with CDC stages II and III, with the highest levels being in patients with stage III and acute ongoing opportunistic infections. For the single component MRP14, significantly raised levels (P < 0.05) were only found in HIV stage III individuals with acute clinical events. Similar associations were not found for MRP8 alone. Increase was not related to CD4+ cell count. There was a significant correlation between 27E10 antigen serum concentrations and levels of neopterin in patients with HIV stages II and III without acute concurrent illness. Patients being treated with Zidovudine showed no statistically significant variation in levels of 27E10 and its single components MRP8 and MRP14 compared with untreated patients. These findings suggest that elevation of MRP14 levels occurs in HIV+ individuals at later stages post-HIV infection, after the onset of opportunistic infections. 27E10 antigen is concluded to be a potential marker for the different stages of HIV disease.     

急性白血病病人GST-π、MRP1表达及其相关性的临床研究

目的：检测急性白血病（acute leukemia，AL）病人谷胱甘肽硫转移酶-π（glutathione—S—transferltse-π，GST-π）、多药耐药相关蛋白1（multi—drug resistance relevant protein 1，MRP1）的表达，探讨二者与AL多药耐药（multi—drug resistance，MDR）的关系及临床意义，明确二者在AL中的表达有无相关性以及两者表达与AL病人临床特征的关系。方法：采用免疫组织化学S—P法检测80例AL病人及30例正常人外周血单个核细胞GST-π、MPP1表达。运用SPSS10．0统计软件，采用X^2检验、四格表精确概率法、t检验、直线相关分析方法统计结果。结果：GST-π、MRP1在难治组的阳性率均高于初治组和完全缓解组；在初治组的阳性率均高于对照组。GST-π、MRP1在AL难治组中的表达具有高度相关性。GST-π、MRP1表达阳性组完全缓解率低于阴性组。GST-π、MRP1的表达与AL难治组病人年龄、性别、骨髓幼稚细胞比例及外周血白细胞计数无关。且两者在急性淋巴细胞白血病（acute lymphoblastic leukemia，ALL）组、急性非淋巴细胞白血病（acute nonlymphoblastic leukemia，ANLL）组表达无差别。结论：GST-π和MRP1的高表达与AL临床耐药有关；GST-π和MRP1在难治组中的表达密切相关；GST-π和MRP1表达阳性的AL病人的完全缓解率明显降低，两者可能是影响AL疗效的重要指标；GST-π和MRP1在难治组表达阳性率与年龄、性别、外周血白细胞计数、骨髓幼稚细胞比例可能无关，且在ALL组与ANLL组中差别无统计学意义。     

Cellular Pharmacokinetic Model-Based Analysis of Genistein,Glyceollin, and MK-571 Effects on 5 (and 6)-Carboxy-2′,7′-Dichloroflourescein Disposition in Caco-2 Cells

Pharmacokinetic modeling was used to describe 5 (and 6)-carboxy-2′,7′-dichloroflourescein (CDF) disposition in Caco-2 cells following CDF or CDFDA (CDF diacetate) dosing. CDF transcellular flux was modeled by simple passive diffusion. CDFDA dosing models were based on simultaneous fitting of CDF levels in apical, basolateral, and intracellular compartments. Predicted CDF efflux was 50% higher across the apical versus the basolateral membrane. This difference was similar following apical and basolateral CDFDA dosing, despite intracellular levels being 3-fold higher following basolateral dosing, thus supporting nonsaturable CDF efflux kinetics. A 3-compartment catenary model with intracellular CDFDA hydrolysis described CDF disposition. This model predicted that apical CDF efflux was not altered in the presence of MK-571, and that basolateral membrane clearance was enhanced to account for reduced intracellular CDF in the presence of this multidrug resistance-associated protein (MRP) inhibitor. Similar effects were predicted for glyceollin, while genistein exposure had no predicted effects on CDF efflux. These modulator effects are discussed in the context of model predicted intracellular CDF concentrations relative to reports of CDF affinity (measured by K_m) for MRP2 and MRP3. This model-based analysis confirms the complexity of efflux kinetics and suggests that other transporters may have contributed to CDF efflux.     

The MDR1 (P-glycoprotein) and MRP (P-190) transporters do not play a major role in the intrinsic multiple drug resistance of Jurkat T lymphocytes

The response of T cells in relation to the cell cycle has not been extensively studied. We have attempted to address this question using Jurkat T cells treated with cytostatic drugs known to arrest cells at various transition points of their cycle. We tested several concentrations of drugs that act at G1/S (hydroxyurea, lovastatin, thymidine), early S (aphidicolin, cyclosporin A, rapamycin) or G2+M (colchicine, nocodazole) in 24 h cultures. Cytofluorimetric analyses showed that cycling Jurkat cells were equally distributed between the G1 (44.9 ± 6.5%) and S (42.3 ± 8.0%) phases. Cell distribution in G2+M was 12.7 ± 2.8%. Hydroxyurea but not lovastatin increased the percentage of cells in S phase to ≈60–70% and both drugs decreased it to ≈30% in G1. Thymidine had no effects. Aphidicolin increased the distribution in S phase to ≈70% with a decrease in G1 to ≈30%. Cyclosporin A and rapamycin increased the percentage of the cells in G1 to ≈70% and decreased it to ≈25% in S phase. Nocodazole increased cell distribution in G2+M to ≈60% and induced a decrease in G1 to ≈10%. The effects of the drugs were not related to their toxicity and their limited efficiency raised the possibility that Jurkat cells possessed an intrinsic resistance to these xenobiotics. Time-course analysis showed (scanning electron microscopy) that the early morphological changes induced by colchicine were reversible. Drug efflux experiments (vinblastine) suggested that an ATP-dependent process could be involved. However, Northern blot analyses showed a weak signal for MDR1 (P-glycoprotein). In contrast, a probe for MRP (P-190) showed a strong signal in Jurkat and peripheral lymphocytes. The presence of drugs (cyclosporin A, nocodazole, thymidine) (24 h) did not upregulate its message and cell treatment with -butathione (S,R)-sulfoximine only moderately affected the efficiency of the glutathione S-conjugate MRP transporter. Our data suggest that the intrinsic multidrug resistance of leukemic Jurkat T cells does not appear to involve the MDR1 and MRP members of the ABC family of reverse drug transporters and these observations raise the possibility of the involvement of multifaceted mechanisms.     

胰腺癌多药耐药细胞株BxPC-3/ADM的建立及耐药机制的初步探讨

目的 构建胰腺癌多药耐药细胞株BxPC-3/ADM,通过动态监测诱导耐药过程,探讨其耐药的可能机制.方法 逐步增加阿霉素浓度对BxPC-3细胞进行诱导,在不同的阿霉素诱导浓度,MTT法检测细胞对多种化疗药物的耐药指数,RT-PCR和Western印迹法检测细胞MDR1和MRP mRNA和蛋白的表达.结果 成功构建多药耐药细胞株BxPC-3/ADM;在0.05 μg/ml至8 μg/ml阿霉素诱导浓度,细胞对5-Fu、MMC和Gem的耐药指数无明显增加;在16 μg/ml浓度3种化疗药物的耐药指数有较明显上升,同时伴有MDR1 mRNA表达的明显增加;至32 μg/ml 5-Fu和Gem的耐药指数未再有继续上升,而MMC的耐药指数则继续上升,同时MDR1 mRNA表达未再增加,而MRP mRNA表达则明显增加.Western印迹实验显示MDR1和MRP蛋白表达变化与mRNA表达变化趋势一致.结论 MDR1基因在诱导早期的耐药中起主导作用,在后期则和MRP基因协同发挥作用.     

siRNA干扰Caco-2细胞鞘磷脂合酶2 (SMS2)基因对药物转运体的影响

 目的  研究鞘磷脂合酶2 (sphingomyelin synthase 2,SMS2)缺损对人结肠癌细胞(colon cancer cell,Caco-2)中药物转运体P 糖蛋白(P-glycoprotein,P-gp)及多药耐药相关蛋白2 (multidrug resistance-associated protein 2,MRP2)的表达与功能的影响。方法  SMS2特异性siRNA转染至Caco-2细胞。采用RT-PCR和real-time PCR检测SMS2-特异性siRNA的干扰效率;采用Western blot法检测siRNA转染后P-gp和 MRP2蛋白表达的变化;采用胞内蓄积试验,通过HPLC检测P-gp及MRP2专一性底物罗丹明123及普伐他汀的蓄积含量,分析下调SMS2水平对Caco-2细胞中P-gp及MRP2功能的影响。结果  应用siRNA下调SMS2水平后,P-gp和MRP2的蛋白质水平均显著下调;胞内蓄积实验结果显示罗丹明123及普伐他汀的蓄积量明显增加,说明P-gp和MRP2的外排功能减弱。结论  SMS2基因表达下调对Caco-2细胞中P-gp和MRP2的表达以及功能均有显著影响。     

靛玉红肠吸收转运机制的研究

目的:探讨靛玉红肠吸收转运机制。方法:采用缚管翻转肠囊模型,以维拉帕米为P-糖蛋白抑制剂,丙磺舒为多药耐药相关蛋白(MRP)抑制剂,2,4-二硝基苯酚(DNP)为能量抑制剂,考察加入抑制剂前后药物在空肠和回肠部位的转运量的变化。结果:靛玉红在空肠和回肠部位的转运量无显著性差异(P>0.05);加入抑制剂前后在空肠和回肠部位的转运量亦无显著性差异(P>0.05);通过吸收动力学的研究,发现靛玉红的吸收符合一级吸收模型,Ka为0.015 min-1,且单位时间吸收药量与浓度成正比,符合Fick′s扩散原理。结论:靛玉红的小肠吸收为典型的被动扩散吸收机制。     

Assessment of multidrug resistance on cell coculture patterns using scanning electrochemical microscopy

The emergence of resistance to multiple unrelated chemotherapeutic drugs impedes the treatment of several cancers. Although the involvement of ATP-binding cassette transporters has long been known, there is no in situ method capable of tracking this transporter-related resistance at the single-cell level without interfering with the cell’s environment or metabolism. Here, we demonstrate that scanning electrochemical microscopy (SECM) can quantitatively and noninvasively track multidrug resistance-related protein 1–dependent multidrug resistance in patterned adenocarcinoma cervical cancer cells. Nonresistant human cancer cells and their multidrug resistant variants are arranged in a side-by-side format using a stencil-based patterning scheme, allowing for precise positioning of target cells underneath the SECM sensor. SECM measurements of the patterned cells, performed with ferrocenemethanol and [Ru(NH₃)₆]³⁺ serving as electrochemical indicators, are used to establish a kinetic “map” of constant-height SECM scans, free of topography contributions. The concept underlying the work described herein may help evaluate the effectiveness of treatment administration strategies targeting reduced drug efflux.     

ABCC11/MRP8 Expression in the Gastrointestinal Tract and a Novel Role for?Pepsinogen Secretion

ATP-binding cassette (ABC) transporters are involved in chemotherapy resistance. Multidrug-resistance protein 8 (ABCC11/MRP8) is also involved in 5-fluorouracil (5-FU) metabolism. 5-FU and its derivatives are widely used in the treatment of gastrointestinal tract cancers, but little is known about the contribution of ABCC11/MRP8 to gastrointestinal tract and related cancers. Here, we report our investigation of ABCC11/MRP8 expression in normal and cancerous gastrointestinal tract tissues and reveal its novel role in the gastric mucosa. In tissue microarray and surgically resected cancer specimens, immunohistochemical (IHC) staining revealed significantly reduced expression of ABCC11/MRP8 in gastrointestinal tract cancers compared with other cancers. In contrast, strong ABCC11/MRP8 expression was observed in normal gastric mucosa. Additional immuno­fluorescence assays revealed co-localization of ABCC11/MRP8 and pepsinogen I in normal gastric chief cells. Quantitative PCR and Western blot analysis also revealed significant expression of ABCC11/MRP8 in fundic mucosa where the chief cells are mainly located. Furthermore, the ABCC11 mRNA-suppressed NCI-N87 gastric cancer cell line failed to secret pepsinogen I extracellularly. Thus, low expression of ABCC11/MRP8 is consistent with chemotherapeutic regimens using 5-FU and its derivatives in gastrointestinal tract cancers. Our results indicated a novel function of ABCC11/MRP8 in the regulation of pepsinogen I secretion in the normal gastric chief cells.