分割剂量电离辐射对卵巢癌细胞多药耐药的影响

目的 研究不同分割剂量电离辐射方案对卵巢癌细胞多药耐药性的影响.方法 采用卵巢癌亲本细胞SKOV3及其耐药细胞株SKVCR,分别进行假照射、单次照射(10 Gy)、常规分割照射(2 Gy ×5)和超分割照射(1 Gy×2 ×5).MTT方法检测细胞对4种化疗药物硫酸长春新碱( vincristine,VCR)、依托泊苷(etoposide,VP-16)、盐酸吡柔比星(pirarubicin,THP)和顺铂(cisplatin,DDP)敏感性的变化.Western blot检测P-gp蛋白表达量.结果 与SKOV3相比,SKVCR倍增时间增加为1.8倍,P-gp糖蛋白表达增高,4种药物对SKVCR的IC50浓度明显增加(P＜0.05).在SKOV3中,与假照组相比,单次照射后细胞对THP、DDP药敏性降低,常规分割照射后细胞对VCR、THP、VP-16药敏性降低,超分割照射使VP-16药敏性降低;在SKVCR中,与假照组相比,3个照射组对VCR、VP-16的药敏性增高,对DDP的药敏性无明显改变,单次和分割照射均可降低P-gp表达.结论 单次、分割和超分割照射在SKOV3亲本细胞中诱导多药耐药,在耐药株SKVCR中逆转对VCR、VP-16的耐药性.     

百草枯诱导的慢性帕金森病模型大鼠血脑屏障和P-gP变化的研究

目的：探讨百草枯诱导的慢性帕金森病模型中大鼠血脑屏障功能和P-糖蛋白表达的变化。方法：随机将动物分成3组：对照组（生理盐水注射组）和模型组（百草枯注射4周、8周组）。以免疫组织化学染色方法显示各组中脑酪氨酸羟化酶（TH）阳性细胞、免疫印迹检测TH蛋白表达和P-糖蛋白表达、Belyaevs＇法使用EB测定BBB通透性。进行统计学分析。结果：与对照组相比,模型组TH阳性神经元和TH蛋白表达较对照组明显减少（P〈o．05）;模型组大鼠BBB的通透性显著增加（P〈0．05）;与对照组比较,模型组P-gP表达显著降低（P〈0．05）。结论：百草枯可通过使TH阳性神经元和TH蛋白表达减少,诱导大鼠慢性帕金森病模型;同时导致BBB通透性增加和P-糖蛋白表达下降,百草枯可能通过影响BBB通透性和P-糖蛋白的表达诱导帕金森病。     

罗格列酮逆转丝裂霉素对人胃癌 SGC7901／VCR祼鼠移植瘤耐药作用的研究

目的：探讨 PPARγ激动剂罗格列酮（ ROS ）逆转人胃癌 SGC7901／VCR 细胞裸鼠移植瘤对丝裂霉素（ MMC）的耐药作用及其可能机制。方法建立人胃癌SGC7901／VCR细胞裸鼠移植瘤模型,将48只裸鼠随机分为6组：空白对照组（生理盐水0．2 ml）、MMC组（ MMC 2．5 mg／kg）、ROS组（ ROS 100 mg／kg）、MMC＋ROS中剂量组（ MMC 2．5 mg／kg＋ROS 50 mg／kg）、MMC＋ROS高剂量组（MMC 2．5 mg／kg＋ROS 100 mg／kg）、MMC＋CSA组（MMC 2．5 mg／kg＋CSA 50 mg／kg）。每组8只裸鼠;用药40天后,观察各组裸鼠体重和移植瘤体积变化,计算抑瘤率,绘制移植瘤的生长曲线;Western-blot法检测P-gp和MGr1-Ag蛋白的表达。结果空白对照组、MMC组移植瘤瘤体积和抑瘤率差异无显著性,ROS组、MMC＋ROS中剂量组、MMC＋ROS高剂量组组、MMC＋CSA组与空白对照组、MMC组比较,移植瘤瘤体积和抑瘤率差异有显著性。空白对照组、MMC组中P-gp、MGr1-Ag蛋白表达最强,ROS组、MMC＋ROS中剂量组、MMC＋ROS大剂量组、MMC＋CSA组与空白对照组和MMC组P-gp、MGr1-Ag蛋白表达比较有统计学意义（ P＜0．05）,MMC＋ROS大剂量组、MMC＋CSA组中其表达最弱,组间差异无统计学意义（P＞0．05）。结论罗格列酮可抑制人胃癌SGC7901／VCR细胞祼鼠移植瘤瘤体生长,罗格列酮可下调人胃癌SGC7901／VCR细胞裸鼠移植瘤组织中P-gp和MGr1-Ag蛋白的表达。罗格列酮可部分逆转人胃癌SGC7901／VCR细胞祼鼠移植瘤对丝裂霉素的耐药性。     

阿帕替尼逆转P-gp转运体介导的乳腺癌化疗多药耐药性的作用及其机制

目的 探讨阿帕替尼对人乳腺癌化疗多药耐药性的逆转作用及其机制。方法 不同浓度的阿帕替尼作用于体外培养的人乳腺癌MCF-7及MCF-7/ADR细胞48 h,MTT法检测阿帕替尼对两种细胞的细胞毒性;低毒浓度的阿帕替尼与化疗药物紫杉醇及阿霉素联用,探讨阿帕替尼对两种细胞化疗耐药性的影响;采用流式细胞术检测阿帕替尼对罗丹明123在MCF-7及MCF-7/ADR细胞内蓄积的影响;采用Pgp-Glo? Assay Systems试剂盒观察阿帕替尼对多药耐药相关蛋白P-gp的ATPase活性的影响;采用Western blot法检测阿帕替尼对P-gp表达及AKT磷酸化的影响。结果 阿帕替尼可浓度依赖性地逆转乳腺癌MCF-7/ADR细胞对紫杉醇及阿霉素的多药耐药性（P<0.05）、增加罗丹明123在MCF-7/ADR细胞内的蓄积（P<0.05）及激活P-gp转运体的ATPase活性（P<0.05）,而对P-gp的表达没有影响;此外,阿帕替尼不改变AKT的磷酸化水平。结论 阿帕替尼可能通过抑制P-gp转运体的外排功能逆转P-gp转运体介导的乳腺癌化疗多药耐药性。     

白藜芦醇通过拮抗hPXR对P-gp的影响

目的研究白藜芦醇通过拮抗hPXR对P-gp基因(MDR1)、蛋白表达及活性的影响。方法在LS174T细胞中,采用瞬时共转染报告基因实验研究白藜芦醇对PXR介导的MDR1的转录调节作用,并进一步应用Real-Time定量PCR和Western blot方法检测白藜芦醇作用24 h后对利福平诱导的P-gp基因和蛋白变化的影响,罗丹明转运实验考察P-gp活性的变化。结果双荧光素酶报告基因检测结果显示,25和50μmol.L-1白藜芦醇可通过拮抗PXR将利福平对MDR1的诱导作用由4.70倍分别降至1.76倍和0.69倍(P<0.01),在过表达hPXR的LS174T细胞中,50μmol.L-1白藜芦醇可以将利福平诱导的MDR1 mRNA水平由1.8倍降至1.3倍(P<0.05),Western blot结果表明白藜芦醇也可降低利福平诱导的P-gp表达。此外,罗丹明转运实验显示,25和50μmol.L-1白藜芦醇可以将利福平抑制的累积量由77.7%升至91.7%和95.1%(P<0.05),表明白藜芦醇可降低利福平诱导的P-gp活性。结论白藜芦醇可以通过拮抗PXR而影响P-gp的基因、蛋白表达及活性。     

Quantitative structure activity relationship studies on the flavonoid mediated inhibition of multidrug resistance proteins 1 and 2

In the present study, the effects of a large series of flavonoids on multidrug resistance proteins (MRPs) were studied in MRP1 and MRP2 transfected MDCKII cells. The results were used to define the structural requirements of flavonoids necessary for potent inhibition of MRP1- and MRP2-mediated calcein transport in a cellular model. Several of the methoxylated flavonoids are among the best MRP1 inhibitors (IC(50) values, ranging between 2.7 and 14.3 microM) followed by robinetin, myricetin and quercetin (IC(50) values ranging between 13.6 and 21.8 microM). Regarding inhibition of MRP2 activity especially robinetin and myricetin appeared to be good inhibitors (IC(50) values of 15.0 and 22.2 microM, respectively). Kinetic characterization revealed that the two transporters differ marginally in the apparent K(m) for the substrate calcein. For one flavonoid, robinetin, the kinetics of inhibition were studied in more detail and revealed competitive inhibition with respect to calcein, with apparent inhibition constants of 5.0 microM for MRP1 and 8.5 microM for MRP2. For inhibition of MRP1, a quantitative structure activity relationship (QSAR) was obtained that indicates three structural characteristics to be of major importance for MRP1 inhibition by flavonoids: the total number of methoxylated moieties, the total number of hydroxyl groups and the dihedral angle between the B- and C-ring. Regarding MRP2 mediated calcein efflux inhibition, only the presence of a flavonol B-ring pyrogallol group seems to be an important structural characteristic. Overall, this study provides insight in the structural characteristics involved in MRP inhibition and explores the differences between inhibitors of these two transporters, MRP1 and MRP2. Ultimately, MRP2 displays higher selectivity for flavonoid type inhibition than MRP1.     

鼓槌石斛中毛兰素及鼓槌素对B16／h MDR—1细胞的药耐药性的作用

采用转染上人类MDR－1基因，对长春花碱及阿霉素具有交叉耐药性的鼠黑色素瘤细胞株对从鼓槌石斛中分得的二个氢芪类化合物毛兰素及鼓槌素的抗肿瘤多药耐药性进行研究。结果表明：二个化合物均能在一定程度上增加阿霉素在多药耐药细胞株中的积累，有进一步研究的价值。     

得力生对胃癌细胞P-gp、GST-π表达的影响

目的:研究得力生注射液对胃癌细胞P-gp、GST-π表达的影响。方法:采用免疫荧光结合激光扫描共聚焦显微镜技术观察胃癌细胞株SGC-7901P-gp、GST-π表达。结果:得力生浓度分别为0μl/ml、1.25μl/ml、2.5μl/ml、5.0μl/ml时,SGC-7901细胞P-gp的表达逐渐减低,各组之间有统计学差异(P<0.05);GST-π的表达亦逐渐减低,各组之间有统计学差异(P<0.05)。结论:得力生注射液可下调胃癌细胞P-gp、GST-π的表达。     

荷瘤小鼠多药耐药(MDR1)基因转染后P-gp体内表达的研究

目的：探讨恶性肿瘤MDR1基因治疗过程中，MDR1基因在体内的表达。方法：骨髓造血细胞转染MDR1基因后，程序性移植入预先照射亚致死剂量^60Co-γ射线的荷瘤小鼠，取骨髓造血细胞、肿瘤实体做P-糖蛋白免疫组化并做RT-PCR以观察MDRI基因的表达情况。结果：各剂量组MDRI基因转染后随时间骨髓造血细胞P-糖蛋白表达逐渐增加，各剂量组之间无明显差异。P-糖蛋白表达化疗剂量较大组明显高于化疗剂量较小组。结论：MDRI基因转染在骨髓造血细胞有较高表达，对肿瘤实体、肝脏、肾脏P-糖蛋白表达无影响。     

The role of the human ABCG2 multidrug transporter and its variants in cancer therapy and toxicology

The human multidrug resistance ABC transporters provide a protective function in our body against a large number of toxic compounds. These proteins, residing in the plasma membrane, perform an active, ATP-dependent extrusion of such xenobiotics. However, the same proteins are also used by the tumor cells to fight various anticancer agents. ABCG2 is an important member of the multidrug resistance proteins, an 'ABC half transporter', which functions as a homodimer in the cell membrane. In this review, we provide a basic overview of ABCG2 function in physiology and drug metabolism, but concentrate on the discussion of mutations and polymorphisms discovered in this protein. Interestingly, a single nucleotide mutation, changing amino acid 482 from arginine to threonine or glycine in ABCG2, results in a major increase in the catalytic activity and a wider drug recognition by this protein. Still, this mutation proved to be an in vitro artifact, produced only in heavily drug-selected cell lines. In contrast, at least two, but possibly more polymorphic variants of ABCG2 were found to be present in large human populations with different ethnic background. However, currently available experimental data regarding the cellular expression, localization and function of these ABCG2 variants are strongly contradictory. Since, the proteins produced by these variant alleles may differently modulate cancer treatment, general drug absorption and toxicity, may represent risk factors in fetal toxicity, or alter the differentiation of stem cells, their exact characterization is a major challenge in this field.