EXPRESSION OF MULTIDRUG RESISTANCE-ASSOCIATED PROTEIN (MRP) AND ITS RELATIONSHIP WITH CLINICOPATHOLOGICAL FACTORS IN NON-SMALL CELL LUNG CANCER

Objective: To investigate the relationship between the expression of multidrug resistance-associated protein (MRP) and clinicopathological factors and prognosis. Methods: The expression of MRP in 62 cases with non-small cell lung cancer (NSCLC) was detected using immunohistochemistry method. The expression of MRP in 30 cases of NSCLC and corresponding normal lung tissues were detected using immunohistochemistry and Western Blot. Results: this study of tumor tissues confirmed the plasma membrane and/or cytoplasm locations of MRP. There was apparent difference between normal lung tissues and NSCLC in MRP. The survival analysis of 62 NSCLC showed that the mean survival time of the patients with negative MRP expression was 69.8117.41 months and that of patients with positive MRP expression, 25.384.46 months. Log-rank test suggested that the difference between them was significant (P=0.0156). It was also found that in squamous cell lung cancer the statistically significant difference between the mean survival time of patients with positive MRP expression and those with negative MRP expression (P=0.0153). Multivariate Cox model analysis suggested that the survival time was significantly related to expression of MRP (P=0.035) and lymphatic metastasis (P=0.038). Conclusion: MRP expression in NSCLC is significantly higher compared with normal lung tissues. The mean survival time of patients with negative MRP was relative longer and expression of MRP was an independent factor for prognosis.

GST-π、ERCC1、MRP和LRP在卵巢癌组织中的表达及意义

目的探讨谷胱甘肽S-转移酶π(GST-π)、切除修复交叉互补基因(ERCC1)、多药耐药相关蛋白(MRP)及肺耐药相关蛋白(LRP)在上皮性卵巢癌组织中的表达及临床意义。方法采用免疫组织化学技术检测67例卵巢恶性肿瘤、20例卵巢良性肿瘤和16例正常卵巢组织中GST-π、ERCC1、MRP及LRP的表达状况,并对相关的临床病理因素进行分析。结果①67例卵巢癌中,GST-π、MRP和LRP阳性表达均显著高于其在卵巢良性肿瘤和正常卵巢组织中的阳性表达(P<0.05),而ERCC1的阳性表达同卵巢良性肿瘤和正常卵巢组织比较差异无统计学意义(P>0.05)。②GST-π的表达与肿瘤分化程度有关,分化越低表达越高(P<0.05);而ERCC1、MRP和LRP的阳性表达与多种临床病理因素无关(P>0.05)。结论 GST-π、ERCC1、MRP及LRP蛋白在卵巢癌的发生发展及耐药机制中发挥重要作用,联合检测对卵巢癌治疗方案的合理制定及化疗反应性的评估具有积极的临床指导意义。

低频重复经颅磁刺激对氯化锂-匹鲁卡品慢性癫痫大鼠海马CA3区PGP、MRP1、MVP表达的影响

目的研究低频重复经颅磁刺激(rTMS)对氯化锂-匹鲁卡品慢性癫痫大鼠海马CA3区P-糖蛋白(PGP)、多药耐药相关蛋白(MRP)1及主穹隆蛋白(MVP)表达水平的影响。方法 60只大鼠随机分为对照组,模型组,假刺激组,治疗组,每组15只。采用氯化锂-匹鲁卡品腹腔注射构建癫痫大鼠模型,治疗组采用rT MS治疗,比较各组治疗过程中癫痫发作次数及CA3区PGP、MRP1及MVP的表达水平。结果治疗组癫痫发作频率低于模型组及假刺激组(P<0.05)。治疗组PGP、MRP1及MVP表达水平显著低于模型组及假刺激组(P<0.05),较对照组显著升高(P<0.05)。结论低频rTMS可抑制模型大鼠海马CA3区PGP、MRP1及MVP过度表达,低频rTMS的抗痫作用可能与之有关。

Construction of Multi-ribozyme Expression System and Its Characterization of Cleavage on the MDR1/MRP1 Double Target Substrate in vitro

To improve catalytic activity of ribozyme on its substrate, the multi-ribozyme expression system was designed and constructed from 20 cis-acting hammerhead ribozymes undergoing self-cleavage with 10 trans-acting hammerhead ribozymes inserted alternatively regularly and the plasmid of pGEM-MDR1/MRP1 used to transcribe the MDR1/MRPl（196/210） substrate containing double target sites was also constructed by DNA recombination. Endonuclease digestion analysis and DNA sequencing indicate all the recombinant plasmids were correct. The clea- vage activities were evaluated for the multi-ribozyme expression system on the MDR1/MRP1 substrate in the cell free system. The results demonstrate that the cis-acting hammerhead ribozymes in the multi-ribozyme expression system were able to cleave themselves and the 72 nt of 196Rz and the 71 nt of 210Rz trans-acting hammerhead ribozymes were liberated effectively, and the trans-acting hammerhead ribozymes released were able to act on the MDR1/MRP1 double target RNA substrate and cleave the target RNA at specific sites effectively. The multi- ribozyme expression system of the [Coat＇A196Rz/Coat＇B210Rz]5 is more significantly superior to that of the [Coat＇A 196Rz/Coat＇B210Rz] 1 in cleavage of RNA substrate. The fractions cleaved by [Coat＇A 196Rz/Coat＇B210Rz]5 on the MDR1/MRP1 substrate for 8 h at observed temperatures showed no marked difference. The studies of Mg^2＋ on cleavage efficiency indicate that cleavage reaction is dependent on Mg^2＋ ions concentration. The plot of lg（kobs） vs. lgc（Mg^2＋） displays a linear relationship between 2.5 mmol/L and 20 mmol/L Mg^2＋. It suggests that Mg^2＋ ions play a crucial role in multi-ribozyme cleavage on the substrate.

EFFECTS OF NEOADJUVANT CHEMOTHERAPY ON MDR1 AND MRP GENE EXPRESSION IN PRIMARY BREAST CANCER

Objective: To investigate the effects of neoadjuvant chemotherapy on the expression of drug resistance genes, multidrug resistance-1 (MDR1) and multidrug resistance-associated protein (MRP), in patients with primary breast cancer. Methods: MDR1 and MRP expression were detected by semi-quantitative RT-PCR in 20 patients with primary breast cancer, before and after chemotherapy. Results: Before chemotherapy, MDR1 and MRP expression can be detected in 15 cases (75%) and 18 cases (90%) respectively. After chemotherapy, expression of MDR1 is not significantly different from that before chemotherapy, but expression of MRP is significantly different from that before chemotherapy. Conclusion: Expression of drug resistance gene MRP, but not MDR1, is enhanced in patients with primary breast cancer submitted to neoadjuvant chemotherapy.

Effects of Hypoxia on Expression of P-gp and Mutltidrug Resistance Protein in Human Lung Adenocarcinoma A549 Cell Line

To study the effects of hypoxia on the expression of P-gp and mutltidrug resistance protein in human lung adenocarcinoma A549 cell line, and to explore the probable mechanism of hypoxia in tumor cell of MDR. The expression of hypoxia inducible factor-1α, P-gp and mutltidrug resistance protein was immunohistochemically detected by culturing human lung adenocarcinoma A549 cell under hypoxia (2 % O_2) for 24 h. After interaction with adriamycin or cisplatin under hypoxia (2 % O_2) for 24 h, the cell survival rate was detected by MTT. Our results showed that the expression of hypoxia inducible factor-1α, P-gp and mutltidrug resistance protein under hypoxia were higher than the expression under normoxia, and correlations between the expression of HIF-1α and P-gp or multidrug resistance-associated protein was observed (P<0.05). The resistance of adriamycin of A549 cell was enhanced under hypoxia. It is concluded that the resistance of tumor chemotherapy is enhanced in hypoxia. The expression of HIF-1α is obviously correlated with the expression of P-gp and mutltidrug resistance protein.

PFC体内递增诱导建立S180肿瘤多药耐药模型及其稳定性观察

目的小鼠体内诱导建立获得性S180多药耐药（multi—drug resistance，MDR）模型及其稳定性观察。方法模拟临床顺铂＋氟尿嘧啶＋环磷酰胺（PFC）化疗方案给药，分三个阶段剂量递增法诱导S180腹水瘤小鼠，建立获得性S180MDR实验模型。采用噻唑蓝fMTTl法、流式细胞术动态检测各阶段所诱导细胞对化疗药物的耐药倍数、细胞内药物积累量及细胞膜P-糖蛋白（P-glycoprotein，P—gp）功能活性，并通过检测以上指标观察各阶段所诱导细胞停药后的耐药稳定性：采用实时荧光定量PCR（RT—qPCR）法检测各阶段所诱导细胞MDR-1 mRNA、多药耐药相关蛋白-1（multidrug resistance-associated proteinl，MRP-1）mRNA的表达量。结果与亲本细胞对照组比较，各阶段所诱导S180细胞对化疗药物的耐药倍数随着诱导时间延长和剂量增高而逐渐增大，细胞内阿霉素（adriamycin，ADR）积累量逐渐减少，细胞P—gp功能活性逐渐增强;各阶段所诱导S180细胞MDR-1mRNA、MRP-1 mRNA的表达量也与诱导时间和给药剂量呈正相关：第一、二和三阶段所诱导细胞的稳定耐药时间分别为1周、2周和3周左右。结论模拟临床PFC化疗方案给药，采用分阶段剂量递增小鼠体内诱导法可建立耐药强度高、稳定时间长的获得性S180MDR实验模型。

铅暴露TM4细胞中Nrf2对Mrp1表达的调节作用

目的探讨铅暴露小鼠睾丸支持细胞(TM4细胞)核因子E2相关因子2(nuclear factor E2-related factor 2,Nrf2)对多药耐药蛋白1(multidrug resistance protein 1,Mrp1)表达的调节作用。方法将处于对数生长期的TM4细胞分别暴露于含20μmol/L乙酸铅(对照)和10、20、40、80μmol/L叔丁基对苯二酚(tBHQ,Nrf2激活剂)+20μmol/L乙酸铅及含1、2、4、8μmol/L全反视黄酸(ATRA,Nrf2抑制剂)+20μmol/L乙酸铅的培养基培养24 h,采用CCK-8法检测细胞的存活率。将TM4细胞分别暴露于含0(对照)、20μmol/L乙酸铅、20μmol/L乙酸铅+40μmol/L tBHQ、20μmol/L乙酸铅+2μmol/L ATRA继续培养24 h。采用原子吸收光谱法测定细胞铅含量,采用实时荧光定量PCR(qRT-PCR)检测Nrf2与Mrp1mRNA的表达水平,细胞免疫荧光法观察细胞中Nrf2的分布定位情况。结果随着tBHQ、ATRA暴露浓度的升高,铅暴露TM4细胞的存活率均呈先上升后下降的趋势。与对照组比较,80μmol/L tBHQ+20μmol/L乙酸铅组及8μmol/L ATRA+20μmol/L乙酸铅组TM4细胞的存活率均较低,差异有统计学意义(P<0.05)。与对照组相比,乙酸铅组、乙酸铅+tBHQ组、乙酸铅+TARA组TM4细胞中的Nrf2与Mrp1 mRNA表达及铅含量均较高,差异有统计学意义(P<0.05);与铅暴露组比较,乙酸铅+tBHQ组TM4细胞中的Nrf2 mRNA表达及乙酸铅+TARA组TM4细胞中的铅含量均较高,而乙酸铅+TARA组TM4细胞中的Mrp1 mRNA表达较低,差异有统计学意义(P<0.05)。各处理组中Nrf2均未见明显核转位改变。结论铅暴露TM4细胞可以通过Nrf2的激活上调Mrp1的表达。

Different gap junction-propagated effects on cisplatin transfer result in opposite responses to cisplatinin normal cells versus tumor cells

OBJECTIVE Previous work has shown that gap junction intercel ular communication(GJIC)enhances cisplatin(Pt)toxicity in testicular tumor cells but decreases it in non-tumor testicular cells.In this study,these different GJIC-propagated effects were demonstrated in tumor versus non-tumor cells from other organ tissues(liver and lung).METHODS We use several different mani pulations(no cell contact,pharmacological inhibition,and si RNA suppression)to down-regulate GJIC function.The in vivo results using xenograft tumor models were consistent with those from the above-mentioned cells.To better understand the mechanism(s)involved,we studied the effects of GJIC on Pt accumulation in tumor and non-tumor cells from the liver and lung.RESULTS The intracel ular Pt and DNA-Pt adduct contents clearly increased in non-tumor cells but decreasedin tumor cells when GJIC was downregulated.Further analysis indicated that the opposite effectsof GJIC on Pt accumulation in normal versus tumor cells from the liver were due to its different effects on copper transporter1 and multidrug resistance-associated protein2,membrane transporters attributed to intracellular Pt transfer.CONCLUSION GJIC protects normal organs from cisplatin toxicity while enhancing it in tumor cells via its different effects on intracellular Pt transfer.

Efflux Pumps Modulation in Colorectal Adenocarcinoma Cell Lines: The Role of Nuclear Medicine

Introduction: Multidrug resistance (MDR) is one of the major problems of chemotherapy. Overexpression of efflux pumps, such as P-glycoprotein (Pgp), multiple resistance-related protein 1 (MRP-1) and lung resistance protein (LRP) can lead to MDR. Verapamil and L-buthionine-sulfoximine (BSO) are two modulators of these proteins. This study aims to compare 99mTc-Sestamibi transport kinetics in human colorectal adenocarcinoma cell lines, in the presence and absence of the MDR modulators verapamil and BSO. Material and Methods: MDR proteins expression was evaluated in sensitive (WiDr) and resistant (LS1034) human colorectal adenocarcinoma cell lines. Intracellular and plasma membrane Pgp and MRP1, and LRP expression was analyzed by flow-cytometry and western blot. Cellular transport kinetics was assessed using 99mTc-Sestamibi. MDR modulation was evaluated though retention studies in resistant cells after incubation with the modulators. Results: Pgp expression was significantly higher (p≤0.001) in resistant cells. These results were confirmed by western blot analysis. 99mTc-Sestamibi uptake and retention percentage were significantly higher (p99mTc-Sestamibi, there were differences among the MDR modulators used (p99mTc-Sestamibi could indicate MDR phenotype in colorectal adenocarcinoma cells. As the modulators used showed a reversion of the retention profile only for the first minutes, their administration should occur immediately before the administration of cytotoxic drugs.

Reversal effect of bufalin on multidrug resistance in K562/VCR vincristine-resistant leukemia cell line

OBJECTIVE: To probe insights into the reversal effect of bufalin on vincristine-acquired multidrug resistance(MDR) in human leukemia cell line K562/VCR.METHODS: Proliferative inhibition rate and the reversal index(RI) of bufalin were determined by Methyl thiazolyl tetrazolium assay. The uptake of Adriamycin(ADM) in K562/VCR cells, cell cycle and apoptosis rate were determined by flow cytometry(FCM). Cell morphologic changes were observed with Wright-Giemsa staining. The expression of P-glycoprotein(P-gp), multidrug-associated protein-1(MRP1), Bcl-x L and Bax protein were measured by immunocytochemistry.RESULTS: The human leukemia multidrug resistant K562/VCR cells showed no cross-resistance to bufalin. The RIs of bufalin at concentrations of 0.0002,0.001 and 0.005 μmol/L were 4.85, 6.94 and 14.77,respectively. Preincubation of 0.001 μmol/L bufalin for 2 h could increase intracellular ADM fluorescence intensity to 28.07%(P<0.05) and down-regulate MRP1 expression simultaneously, but no remarkable effect was found on P-gp protein. Cell cycle analysis indicated increased apoptosis rate and apparent decreased G2/M phase proportion after treatment with bufalin. When exposed to 0.01μmol/L bufalin, typical morphological changes of apoptosis could be observed. Down-regulation of Bcl-x L and up-regulation of Bax expression in K562/VCR cells could be detected by immunocytochemistry.CONCLUSION: Bufalin could partly reverse the MDR of K562/VCR cells, with a possible mechanism of down-regulating MRP1 expression and activating apoptosis pathway by altering Bcl-x L/Bax ratio.