CMH为KBv200耐药相关中性鞘糖脂

为了研究耐药细胞株KBv200中性鞘糖脂表达的规律，采用改良的Hakomori法提取、纯化了KB及其耐药细胞株KBv200的中性鞘糖脂，行高效薄层层析，分析其含量的异同；并以糖脂合成抑制剂PPMP抑制KBv200中性鞘糖脂的合成，观察了其对KBv200耐药性的逆转作用。结果发现：KBv200的CMH和CDH表达较KB强，尤以CMH为著，PPMP能抑制KBv200细胞CMH的合成，并能逆转KBv200对长春新碱（VCR）的耐药性。说明CMH为HBv200耐药相关中性鞘糖脂，抑制耐药细胞CMH的合成可能是逆转肿瘤多药耐药的一种新方法。     

PPMP调控KBv_(200)细胞株mdr1基因表达逆转其多药耐药

为研究糖脂合成酶抑制剂苯基棕榈酰胺吗啡丙醇 (DL threo 1 phenyl 2 palmitoylamino 3 morpholi no 1 propanol·HCl,PPMP)对人恶性肿瘤多药耐药细胞株KBv2 0 0 多药耐药mdr1基因的mRNA表达的调控 ,以及PPMP对细胞株KBv2 0 0 的多药耐药性的逆转作用 ,作者应用体外细胞培养技术对细胞株KBv2 0 0 进行PPMP处理 ,用RT PCR技术分析PPMP处理前后细胞mdr1的mRNA表达 ,以流式细胞仪检测PPMP处理前后KBv2 0 0 及其敏感株KB细胞内罗丹明 12 3的药物浓度变化。结果显示 5 μmol/L、15 μmol/LPPMP可部分抑制KBv2 0 0 细胞mdr1mRNA表达 ,2 5 μmol/LPPMP可完全抑制KBv2 0 0 细胞mdr1mRNA表达 ;PPMP可增加KBv2 0 0 细胞内罗丹明荧光强度 ,随着PPMP浓度的增加 ,耐药细胞内的罗丹明荧光强度逐渐增大。提示PPMP对细胞株KBv2 0 0 的多药耐药基因mdr1有抑制作用 ,并可以逆转KBv2 0 0 的多药耐药性 ,逆转作用与PPMP浓度呈正相关     

肿瘤耐药相关鞘糖脂CMH对人树突状细胞B7表达的影响

为了探讨肿瘤耐药相关鞘糖脂CMH在耐药肿瘤细胞免疫逃避中的作用,用柱层析的方法分离纯化了KBv200细胞的耐药相关中性鞘糖脂CMH,采用流式细胞仪技术检测CMH作用前后人树突状细胞（DC）B7抗原的表达。结果显示,CMH明显地抑制DC B7抗原的表达,说明肿瘤耐药相关鞘糖脂可能是通过对DC的影响而抑制机体的免疫反应。     

卵巢癌细胞株COC1／DDP多药耐药逆转对中性鞘糖脂表达的调控作用

对探讨逆转卵巢癌细胞株的多药耐药性（MDR）对细胞表面中性鞘糖脂（N-GSLs）表达的调控作用,以三苯氧胺（TAM）和维拉帕米（VRP）为逆转剂,用MTT法分析了TAM、VPP的逆转效应,采用改良的Hakamori方法提取,纯化了耐药亚株COC1/DDP MDP逆转前后及亲本株COC1细胞的N-GSLs,高效薄层层析（HPTLC）分析了N-GSLs的表达。结果显示,COC1/DDP和COC1的N-GSLs表达有显著差异,COC1/DDP的CMH表达较COC1强,经TAM、VRP作用后,COC1/DDP的耐药性发生逆转,CMH表达降低。说明卵巢癌的多药耐药性与中性鞘糖脂CMH相关,CMH可能为卵巢癌MDR相关鞘糖脂抗原。     

肿瘤相关中性鞘糖脂的实验研究

为了探讨中性鞘糖脂与肿瘤发生、抗原调控、免疫逃避的关系，实验系统研究了中性鞘糖脂在胚胎及肿瘤组织中的表达规律及临床意义，分析了正常及异常表达的鞘糖脂对肿瘤细胞生长调控、免疫逃避和多药耐药的影响。发现了肿瘤胚胎相关抗原CDH、肿瘤耐药相关中性鞘糖脂CMH和肿瘤抑制因子Globoside；揭示了抑制糖脂合成及法N-糖基化在逆转肿瘤耐药和肿瘤治疗中的重要意义。     

辐射促进多药耐药反义寡核苷酸逆转耐药的实验研究

目的探讨辐射促转染的多药耐药基因（mdr1）反义寡核苷酸（ASON）逆转肿瘤细胞KBv200的耐药效果。方法应用MTT法比较脂质体介导的ASON直接转染与联合辐射转染的情况下KBv200细胞对长春新碱（VCR）的半数抑制量（IC50），再利用RT-PCR方法和流式细胞仪检测两种不同的转染方法对KBv200细胞的mdr1-mRNA及其表达产物P-糖蛋白（P-gp）的调控情况。采用耐药细胞株KBv200移植于裸鼠皮下，肿瘤局部2Gy^60Coγ射线照射后1h，瘤内注射脂质体介导的mdr1ASON，经VCR联合化疗。结果联合照射的ASON组明显优于未照射组（P〈0．05）。KBv200细胞的IC50、mdr1-mRNA的表达水平及P-gp的阳性率，均明显低于未照射组（P〈0．05）。联合照射组与未照射组肿瘤体积和肿瘤重量差异有统计学意义（P〈0．01）。结论辐射促转染的mdr1 ASON对肿瘤细胞具有较强的耐药逆转作用。     

整合素β-1对绒毛膜癌细胞耐药的影响

目的：探讨耐药绒毛膜癌细胞粘附分子β-1整合素的表达以及其对细胞凋亡的影响,并寻找逆转耐药的途径。方法：采用人绒毛膜癌细胞株JER及耐足叶乙甙细胞株JEG,免疫组化方法检测绒癌细胞和耐药细胞β-1整合素的表达;MTT法、TUNEL法检测其对细胞凋亡的影响。结果：敏感细胞JER、耐药细胞JEG中均有β-1整合素的表达,但耐药细胞的β-1整合素表达总体水平高于敏感细胞（P〈0．01）;在敏感细胞及耐药细胞中加入纤维粘连蛋白FN其凋亡率与未结合FN的细胞相比有明显差异（P〈0．01）;在敏感细胞及耐药细胞中加入抗β-1整合素抗体阻断细胞与β-1整合素的结合,同时加入纤维粘连蛋白FN,其凋亡率与只加入FN时相比差异有显著性（P〈0．01）。结论：耐药绒癌细胞β-1整合素表达增加,成为耐药表型;其机制主要通过抑制细胞凋亡产生耐药;阻断其作用可以逆转肿瘤耐药。     

三氧化二砷逆转乳腺癌细胞株MCF-7/ADM多药耐药的研究

目的探讨三氧化二砷（As2O3）体外逆转人乳腺癌细胞多药耐药性的作用及机制。方法采用MTT法检测As2O3的细胞毒作用和处理前后耐药细胞对化疗药物的敏感性,用流式细胞仪检测细胞内阿霉素浓度,通过RT-RCR检测MDR1基因的表达。结果 As2O3在0.25mg/L以下剂量时对MCF-7和MCF-7/ADM耐药细胞株的抑制率均小于15%,半数抑制率（IC50）分别为1.01m/L和1.28mg/L,无细胞毒剂量0.2mg/L的As2O3能部分逆转MCF-7/ADM细胞对阿霉素的耐药性。同时无细胞毒剂量0.2mg/L的As2O3能使MCF-7/ADM细胞内阿霉素浓度明显增加,MDR1表达下降。结论 As2O3具有体外部分逆转人乳腺癌细胞多药耐药性的作用,可能与增加细胞内药物积累、下调MDR1表达有关。     

整合素β-1对绒毛膜癌细胞耐药的影响

目的:探讨耐药绒毛膜癌细胞粘附分子β-1整合素的表达以及其对细胞凋亡的影响,并寻找逆转耐药的途径.方法:采用人绒毛膜癌细胞株JER及耐足叶乙甙细胞株JEG,免疫组化方法检测绒癌细胞和耐药细胞β-1整合素的表达;MTT法、TUNEL法检测其对细胞凋亡的影响.结果:敏感细胞JER、耐药细胞JEG中均有β-1整合素的表达,但耐药细胞的β-1整合素表达总体水平高于敏感细胞(P<0.01);在敏感细胞及耐药细胞中加入纤维粘连蛋白FN其凋亡率与未结合FN的细胞相比有明显差异(P<0.01);在敏感细胞及耐药细胞中加入抗β-1整合素抗体阻断细胞与β-1整合素的结合,同时加入纤维粘连蛋白FN,其凋亡率与只加入FN时相比差异有显著性(P<0.01).结论:耐药绒癌细胞β-1整合素表达增加,成为耐药表型;其机制主要通过抑制细胞凋亡产生耐药;阻断其作用可以逆转肿瘤耐药.     

人淋巴瘤Raji/DEX耐药细胞株的建立及其耐药机制

目的建立人淋巴瘤耐药细胞株Raji/地塞米松(DEX)并对其耐药机制进行探讨。方法分别采用噻唑蓝还原法(MTT)确定Raji细胞的半数抑制浓度(IC50)值,DEX浓度递增和持续作用的方法体外诱导Raji细胞的耐药性并检测其耐药指数,Western blot法检测人核转录因子p65(NF-κBp65)蛋白。结果历时3个月后建成的细胞株Raji/DEX增殖速度减慢,体积变小,且对DEX低度耐药,耐药指数为1.7(P<0.05);Raji/DEX的NF-κBp65蛋白表达显著高于Raji亲本细胞(P<0.05)。结论成功建立Raji/DEX耐药细胞株。NF-κBp65蛋白表达增强可能是淋巴瘤细胞产生获得性耐药的主要机制之一。     

PPMP调控KBv200细胞株mdr1基因表达逆转其多药耐药

为研究糖脂合成酶抑制剂苯基棕榈酰胺吗啡丙醇（DL-threo-1-phenyl-2-palmitoylamino-3-morpholino-1-propanol     

Limitations of (99m)Tc tetrofosmin in assessing reversal effects of verapamil on the function of multi-drug resistance associated protein 1

BACKGROUND: Previous reports have demonstrated the feasibility of scintigraphic assessment of the multi-drug resistance (MDR) of tumours caused by ATP binding cassette (ABC) transporters by using Tc cationic tracers such as Tc tetrofosmin (TF). Furthermore, the potential of these tracers for evaluating the effects of reversal agents for MDR has been documented. However, most reversal agents simultaneously affect cationic ion transporters related to tracer accumulation in tumours. METHODS: The uptake of Tc-TF was examined in the MCF7/WT cell line, a wild-type breast cancer cell line that does not exhibit MDR, and its subclonal etoposide resistant cell line MCF7/VP, which expresses high levels of MRP1, one of the multi-drug resistance associated proteins (MRPs), in the presence of increasing concentrations of verapamil, a classical MDR modulator. In the absence of verapamil, MCF7/VP cells showed significantly lower Tc-TF uptake than did MCF7/WT cells, indicating that Tc-TF is a substrate for MRP1. The presence of verapamil enhanced the uptake of Tc-TF in MCF7/VP cells. On the other hand, verapamil also increased tracer uptake in MCF7/WT cells, which was readily appreciated when the uptake values were corrected by viable cell numbers: an approximately 100% increase of Tc-TF uptake was observed in comparison with that in the absence of verapamil in viable MCF7/WT cells whereas a 100-200% increase occurred in viable MCF7/VP cells. In addition, verapamil prolonged the retention of radioactivity in both MCF7/WT cells and MCF7/VP cells. CONCLUSION: These results suggest that cellular functions other than MRP1 function, probably cationic ion transporters, are simultaneously and significantly involved in the verapamil induced changes of cellular uptake of Tc-TF. Tc-TF scintigraphy may overestimate the reversal effects of modulators on chemoresistance caused by MRP1 when the modulators simultaneously affect ion transporters.     

Cytotoxic and photodynamic effects of Photofrin on sensitive and multi-drug-resistant Friend leukaemia cells.

To study cross-resistance to Photofrin (PF) photosensitization, a Friend leukaemia cell line (ADM-RFLC) with a high level of multi-drug resistance (MDR) and the parental sensitive cell line (FLC) have been used. PF uptake measured by HPLC shows a similar intracellular drug accumulation in both cell lines. The ID50s for cell growth inhibition by PF are also similar after exposure in the dark in the two cell lines, while after illumination they are slightly lower in ADM-RFLC than in FLC cells. Moreover, verapamil, known to reverse the MDR phenotype induced by P-glycoprotein over-expression (the drug efflux mechanism), affects equally ADM-RFLC and FLC cells sensitivity to PF. In addition, photodynamic treatment with PF did not reverse the resistance to rhodamine 123 and aclarubicin, but partly reverses resistance of ADM-RFLC cells to antitubulin drugs such as vinblastine or vincristine. These latter results could have clinical application in the treatment of tumours expressing the MDR phenotype.     

补骨脂素对HL60耐药细胞内化疗药物浓度影响研究

目的研究补骨脂素对HT耐药白血病细胞HL60／HT的逆转多药耐药（MDR）作用。方法采用MTT法测定补骨脂素对细胞增殖抑制作用,高效液相色谱法检测细胞内HT的浓度。结果补骨脂素在1～20μmol／L浓度下能不同程度降低HT对HL60／HT细胞的IC50,并不同程度提高细胞内HT浓度。结论补骨脂素能逆转HL60／HT细胞的MDR作用,可能成为一种MDR调节剂。     

Study of tea polyphenol as a reversal agent for carcinoma cell lines' multidrug resistance (study of TP as a MDR reversal agent)

The aim of this study was to examine MDR1 expression product P-glycoprotein (Pgp) and study the effect and mechanism of tea polyphenol (TP) in reversion of multidrug resistance (MDR) in carcinoma cell lines. Immunocytochemical method was used for qualitative detection of Pgp. A comparative study of cytotoxicity and multidrug resistance reversion effect was made by MTT assay for tea polyphenol and quinidine in MCF-7 and MCF-7/Adr cell lines. The multidrug resistance reversion effect and mechanism were studied by measuring the uptake of 99mTc-tetrofosmin in the carcinoma cell lines. (1) The Pgp overexpression in MCF-7/Adr cells was found to be strong positive, while the Pgp expression of MCF-7 was negative. (2) Although both tea polyphenol and quinidine could not remarkably change the toxicity of adriamycin to MCF-7, they could improve the sensitivity of MCF-7/Adr to adriamycin. The reversion index of tea polyphenol and quinidine was 3 and 10 respectively. (3) The cellular uptake of 99mTc-tetrofosmin was remarkably lower in MCF-7/Adr than in MCF-7. The uptake of 99mTc-tetrofosmin in MCF-7/Adr exhibited a 4, 13, 16 fold increase in the presence of 200, 400 and 500 microg/ml of tea polyphenol respectively. The uptake of 99mTc-tetrofosmin in MCF-7/Adr exhibited only a 4-fold increase in the presence of 200 microM of quinidine. Immunocytochemistry can detect P-glycoprotein expression level qualitatively. Tea polyphenol is not only an anti-tumor agent, but also a multidrug resistant modulator similar to quinidine. The multidrug resistance reversion mechanism of tea polyphenol seems to be its inhibition of the activity of P-glycoprotein. Tea polyphenol has the advantage of very low toxicity in tumor treatment.