The Activity of Erianin and Chrysotoxine from Dendrobium chrysotoxum to Reverse Multidrug Resistance in B16/h MDR-1 Cells

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。

REVERSAL EFFECTS OF MIFEPRISTONE ON MULTIDRUG RESISTANCE(MDR) IN DRUG-RESISTANT BREAST CANCER CELL LINE MCF7/ADR IN VITRO AND IN VIVO

To explore the reversal effect of mifepristone on multidrug resistance (MDR) in drug-resistant human breast cancer cell line MCF7/ADR and its mechanisms. Methods: Expression of MDR1 and MDR-associated protein(MRP) mRNA in MCF7/ADR cells was detected using reverse transcription- polymerase chain reaction(RT-PCR). Western blotting was used to assay the protein levels of P-glycoprotein (P-gp) and MRP. Intracellular rhodamine 123 retention and [3H]vincristine (VCR) accumulation were measured by flow cytometry and liquid scintillation counter, respectively. MTT reduction assay was used to determine the sensitivity of cells to the anticancer agent, adriamycin (ADR). Additionally, a MCF7/ADR cell xenograft model was established to assess the reversal effect of mifeprisone on MDR in MCF7/ADR cells in vivo. Results: Miferpristone dose-dependently down- regulated the expression of MDR1 and MRP mRNA in MCF7/ADR cells, accompanied by a significant decrease in the protein levels of P-gp and MRP. After exposure to 5, 10, and 20 mmol/L mifepristone, MCF7/ADR cells showed a 3.87-, 5.81-, and 7.40-fold increase in the accumulation of intracellular VCR(a known substrate of MRP), and a 2.14-, 4.39-, and 5.53-fold increase in the retention of intracellular rhodamine 123(an indicator of P-gp function), respectively. MTT analysis showed that the sensitivity of MCF7/ADR cells to ADR was enhanced by 7.23-, 13.62-, and 20.96-fold after incubation with mifepristone as above-mentioned doses for 96 h. In vivo, mifepristone effectively restored the chemosensitivity of MCF7/ADR cells to ADR. After 8 weeks of administration with ADR(2 mg穔g-1穌-1) alone or in combination with mifepristone(50 mg穔g-1穌-1), the growth inhibitory rate of xenografted tumors in nude mice was 8.08% and 37.25%, respectively. Conclusion: Mifepristone exerts potent reversal effects on MDR in MCF7/ADR cells in vitro and in vivo through down- regulation of MDR1/P-gp and MRP expression and inhibition of P-gp- and MRP-dependent drug efflux, thus increasing the sensitivity to anticancer drug.

Genotyping Characteristics of Human Fecal Escherichia coli and Their Association with Multidrug Resistance in Miyun District, Beijing

Objective To explore the genotyping characteristics of human fecal Escherichia coli(E. coli) and the relationships between antibiotic resistance genes(ARGs) and multidrug resistance(MDR) of E. coli in Miyun District, Beijing, an area with high incidence of infectious diarrheal cases but no related data.Methods Over a period of 3 years, 94 E. coli strains were isolated from fecal samples collected from Miyun District Hospital, a surveillance hospital of the National Pathogen Identification Network. The antibiotic susceptibility of the isolates was determined by the broth microdilution method. ARGs,multilocus sequence typing(MLST), and polymorphism trees were analyzed using whole-genome sequencing data(WGS).Results This study revealed that 68.09% of the isolates had MDR, prevalent and distributed in different clades, with a relatively high rate and low pathogenicity. There was no difference in MDR between the diarrheal(49/70) and healthy groups(15/24).Conclusion We developed a random forest(RF) prediction model of TEM.1 + baeR + mphA + mphB +QnrS1 + AAC.3-IId to identify MDR status, highlighting its potential for early resistance identification. The causes of MDR are likely mobile units transmitting the ARGs. In the future, we will continue to strengthen the monitoring of ARGs and MDR, and increase the number of strains to further verify the accuracy of the MDR markers.

Reversing multidrug resistance by RNA interference through the suppression of MDR1 gene in human hepatoma cells

瞄准：逆行多，由 RNA 干扰(RNAi ) 的药抵抗(MDR ) 调停了在肝细胞瘤房间的 MDR1 抑制。方法：为由 RNAi 技术颠倒 MDR，二不同短发卡 RNA (shRNAs ) 分别地被设计并且构造进 pGenSil-1 原生质标志。他们当时是进一根高度 adriamycin 抵抗的 HepG2 肝细胞瘤房间线(HepG2/ADM ) 的 transfected。MDR 上的 RNAi 效果被即时 PCR，房间细胞毒性试金和玫瑰精评估 123 (Rh123 ) 流出 assy。结果：stably-transfected 克隆显示出 MDR 显型的颠倒的各种各样的度。令人惊讶地， MDR 显型完全在二 transfected 克隆被颠倒。结论：MDR 能被调停 shRNA 的 MDRI 抑制在 HepG2/ADM 房间颠倒，它提供珍贵线索使 multidrug 抵抗的肝细胞瘤房间敏感到反癌症药。

MDRO肺炎感染患者SAA、PCT、Treg细胞及有关因子表达水平

目的探讨血清淀粉样蛋白A(serum amyloid A protein,SAA)、降钙素原(procalcitonin,PCT)、Treg细胞及有关因子在多重耐药菌(multidrug-resisitant organism,MDRO)肺炎感染患者中的表达水平及其与疗效的关联性。方法选取97例MDRO肺炎感染患者为研究对象,根据治疗14 d后的治疗效果分为有效组(73例)和无效组(24例),根据入院时肺炎严重指数(PSI)分为低危(34例)、中危(49例)、高危(14例)三个亚组。比较2组治疗前、治疗7 d后、治疗14 d后SAA、PCT、Treg细胞、超敏C反应蛋白(hs-CRP)、肿瘤坏死因子-α(TNF-α)水平,比较治疗前低危、中危、高危患者血清各指标水平及PSI评分,分析血清各指标水平与PSI评分的相关性。结果与无效组比较,治疗7、14 d后有效组SAA、PCT、hs-CRP、TNF-α水平较低,Treg细胞数较高,差异有统计学意义(P<0.05);治疗前,低危患者SAA、PCT、hs-CRP、TNF-α及PSI评分<中危患者<高危患者,Treg细胞数>中危患者>高危患者,差异有统计学意义(P<0.05);治疗前,SAA、PCT、hs-CRP、TNF-α水平与PSI评分呈正相关,Treg细胞数与PSI评分呈负相关(P<0.05);受试者操作特征(ROC)曲线显示治疗前SAA、PCT、Treg细胞、hs-CRP、TNF-α联合预测治疗无效的AUC大于各指标单独预测。结论MDRO肺炎感染患者SAA、PCT、hs-CRP、TNF-α、Treg细胞数量呈异常表达,且表达水平对预后具有重要影响,临床可监测其水平变化,联合预测预后的价值较高。

In Vitro Study of Ultrasound on Multidrug Resistance in MDR Human Hepatoma HepG_2 Cells

OBJECTIVE The aim of the study was to examine the reversal effects of ultrasound(US) on the MDR in HepG2/ADM,a HepG2 cell line resistant to Adriamycin(ADM),and to study the mechanism of US action.METHODS Using the MTT assay,the effects of US on MDR in HepG2/ADR cells were studied.Before and after the treatment with 0.5W/cm2 low intensity ultrasound(LIUS),the expression of the MDR-related genes,mdr1,mrp and lrp was assayed with the reverse transcriptase polymerase chain reaction(RT-PCR)and the levels of their respective protein expression determined by flow cytometry.By using confocal laser scanning microscopy(CLSM),we examined the intracellular daunorubicin (DNR) distribution,and the effects on the cells of treatment with US or DNR. RESULTS LIUS significantly reversed MDR in HepG2/ADR cells.A er treatment with LIUS at 0.5W/cm2,chemosensitivity to ADM and DNR increased 3.35-fold and 2.81-fold,respectively.The reversal activity by LIUS plus verapamil(VER) was stronger than with either US or VER alone.A er treatment with 0.5W/cm2 ,the expression of both the MDR1 and the MRP mRNA genes began to decline(P<0.01 and P<0.05,respectively);the expression of LRP showed no significant changes.Changes in the expression of the P-glycoprotein(P-gp) and MRP were similar to those of their mRNA expressions.Results of the CLSM showed that administration of US(0.5W/cm2) or VER(15.7μM) with DNR to HepG2/ADM cells showed a significant change in the distribution of DNR in the cells. CONCLUSION Our results show that LIUS can reverse MDR. The reversal effects are stronger than those of either US or VER alone,when combined with VER administration.As LIUS is non-invasive causing no toxicity,it might have potential for clinical application.The reversal mechanism needs further study.

米诺环素联合头孢哌酮舒巴坦对MDR-AB感染重症肺炎患者肺功能及炎性因子的影响

目的 观察米诺环素联合头孢哌酮舒巴坦对多重耐药鲍曼不动杆菌(MDR-AB)感染重症肺炎患者肺功能及炎性因子的影响。方法 选取2020年1月—2023年6月武夷山市立医院收治的MDR-AB感染重症肺炎患者135例,根据随机数字表法分为联合组(68例)和对照组(67例)。在常规治疗基础上,对照组予头孢哌酮舒巴坦治疗,联合组在对照组基础上予米诺环素治疗,2组均治疗2周。比较2组疗效、细菌清除率,治疗前后肺功能[第1秒用力呼气容积(FEV_(1))、用力肺活量(FVC)、FEV_(1)/FVC]、炎性因子[白介素-8(IL-8)、C反应蛋白(CRP)、降钙素原(PCT)]及不良反应。结果 联合组总有效率为97.06%,高于对照组的86.57%(χ^(2)=4.964,P=0.026);联合组细菌总清除率为73.53%,高于对照组的56.72%(χ^(2)=4.204,P=0.040)。治疗2周后,2组FEV_(1)、FVC、FEV_(1)/FVC高于治疗前,且联合组高于对照组(P<0.05或P<0.01);2组IL-8、CRP、PCT水平低于治疗前,且联合组低于对照组(P<0.05或P<0.01)。联合组与对照组不良反应总发生率比较差异无统计学意义(14.71%vs.10.45%,χ^(2)=0.556,P=0.456)。结论 米诺环素联合头孢哌酮舒巴坦治疗MDR-AB感染重症肺炎疗效显著,可促进细菌清除,改善患者肺功能,减轻炎性反应,且安全性较高。

利奈唑胺联合多黏菌素B、亚胺培南治疗老年MDR-AB肺炎患者的效果

目的:观察利奈唑胺联合多黏菌素B、亚胺培南治疗老年多重耐药鲍氏不动杆菌(MDR-AB)肺炎患者的效果。方法:选取2022年1月至2023年1月该院收治的120例老年MDR-AB肺炎患者进行前瞻性研究,按照随机数字表法分为观察组与对照组各60例。对照组采用多黏菌素B联合亚胺培南治疗,观察组在对照组基础上加用利奈唑胺葡萄糖注射液治疗,比较两组治疗总有效率、血清炎性因子[白细胞介素(IL)-6、IL-8、肿瘤坏死因子(TNF-α)]水平、外周血T细胞亚群指标(CD3^(+)、CD4^(+)、CD8^(+)、CD4^(+)/CD8^(+))水平、肺功能指标[用力肺活量(FVC)、最大呼气中段流量(MMF)、呼气峰流速(PEF)]水平和不良反应发生率。结果:观察组治疗总有效率为95.00%,明显高于对照组的83.33%,差异有统计学意义(P<0.05);治疗后,观察组FVC、MMF、PEF、CD3^(+)、CD4^(+)和CD4^(+)/CD8^(+)水平高于对照组,IL-6、IL-8、TNF-α和CD8^(+)水平低于对照组,差异均有统计学意义(P<0.05);两组不良反应发生率比较,差异无统计学意义(P>0.05)。结论:利奈唑胺联合多黏菌素B、亚胺培南治疗老年MDR-AB肺炎患者可提高治疗总有效率和肺功能指标水平,改善T细胞亚群指标水平,以及降低炎性因子水平,效果优于多黏菌素B联合亚胺培南治疗。

Multidrug-Resistant of Escherichia coli and Salmonella spp. Strains in Chicken Feces Intended for Consumption in Open Spaces of Ouagadougou, Burkina Faso

Resistant bacteria can be transmitted to humans through feces or contaminated meat from local chickens. Bacterial strains were isolated from the intestinal contents of 400 local chicken samples from various sales sites. These strains were then characterized using bacteriological and biochemical methods to identify resistant strains. In a study conducted in Ouagadougou, we systematically collected chicken fecal samples from 20 locations across the city, followed by isolation and identification of Salmonella spp. using specific enrichment and culture methods, as well as Escherichia coli. Bacterial strains were characterized using antibiotic resistance profiles were determined through agar diffusion tests, revealing sensitivity or resistance to a range of antibiotics based on established scientific criteria. The results showed that out of the 400 samples collected, 81.25% and 63.5% were contaminated by Escherichia coli and Salmonella spp., respectively. Among these, 86.15% of identified Escherichia coli and 50.78% of Salmonella spp. displayed resistance to at least one tested antibiotic. Among 280 Escherichia coli isolates identified resistant to at least one antibiotic, 31.07% were resistant to cefotaxime (CTX), 20.35% to ceftazidime (CAZ), 21.07% to ceftriaxone (CTR), 75% to amoxicillin clavulanic acid (AMC), 23.57% aztreoname (ATM) and 27.14% were resistant to imipenem (IMP). In the case of the 129 Salmonella spp. isolates resistant to at least one tested antibiotic, 34.88% were resistant to CTX;41.08% to CAZ;35.65% to CTR, 92% to AMC, 39.53% to ATM and finally 47.28% were resistant to IMP. Our study revealed high prevalence of resistance in bacterial strains isolated from local chickens sold outdoors in Ouagadougou. These findings raise significant public health concerns, due to the possible transmission of these resistant strains to humans through the consumption of contaminated meat, thus complicating the treatment of bacterial infections.

Antimicrobial peptides: new hope in the war against multidrug resistance

The discovery of antibiotics marked a golden age in the revolution of human medicine. However,decades later, bacterial infections remain a global healthcare threat, and a return to the pre-antibiotic era seems inevitable if stringent measures are not adopted to curb the rapid emergence and spread of multidrug resistance and the indiscriminate use of antibiotics. In hospital settings, multidrug resistant(MDR) pathogens, including carbapenem-resistant Pseudomonas aeruginosa, vancomycin-resistant enterococci(VRE), methicillin-resistant Staphylococcus aureus(MRSA), and extendedspectrum β-lactamases(ESBL) bearing Acinetobacter baumannii, Escherichia coli, and Klebsiella pneumoniae are amongst the most problematic due to the paucity of treatment options,increased hospital stay, and exorbitant medical costs. Antimicrobial peptides(AMPs) provide an excellent potential strategy for combating these threats. Compared to empirical antibiotics, they show low tendency to select for resistance, rapid killing action, broad-spectrum activity, and extraordinary clinical efficacy against several MDR strains. Therefore, this review highlights multidrug resistance among nosocomial bacterial pathogens and its implications and reiterates the importance of AMPs as next-generation antibiotics for combating MDR superbugs.

Inhibitory effects of emodin, baicalin, schizandrin and berberine on hef A gene: Treatment of Helicobacter pylori-induced multidrug resistance

AIM: To investigate the inhibitory effects of emodin, baicalin, etc.on the hefA gene of multidrug resistance(MDR) in Helicobacter pylori(H.pylori).METHODS: The double dilution method was used to screen MDR H.pylori strains and determine the minimum inhibitory concentrations(MICs) of emodin, baicalin, schizandrin, berberine, clarithromycin, metronidazole, tetracycline, amoxicillin and levofloxacin against H.pylori strains.After the screened MDR stains were treated with emodin, baicalin, schizandrin or berberine at a 1/2 MIC concentration for 48 h, changes in MICs of amoxicillin, tetracycline, levofloxacin, metronidazole and clarithromycin were determined.MDR strains with reduced MICs of amoxicillin were selected to detect the hefA mR NA expression by realtime quantitative PCR.RESULTS: A total of four MDR H.pylori strains were screened.Treatment with emodin, baicalin, schizandrin and berberine significantly decreased the MICs of amoxicillin and tetracycline against some strains, decreased by 1 to 2 times, but did not significantly change the MICs of clarithromycin, levofloxacin, and metronidazole against MDR strains.In the majority of strains with reduced MICs of amoxicillin, hef A m RNA expression was decreased; one-way ANOVA(SPSS 12.0) used for comparative analysis, P < 0.05.CONCLUSION: Emodin, baicalin, schizandrin and berberine significantly decreased the MICs of amoxicillin and tetracycline against some H.pylori strains, possibly by mechanisms associated with decreasing hefA mR NA expression.

JNK1,JNK2,and JNK3 are involved in P-glycoprotein-mediated multidrug resistance of hepatocellular carcinoma cells

BACKGROUND:Multidrug resistance(MDR)is extremely common in hepatocellular carcinoma(HCC)and is a major problem in cancer eradication by limiting the efficacy of chemotherapy.Modulation of c-Jun NH2-terminal kinase(JNK)activation could be a new method to reverse MDR.However,the relationship between JNK activity and MDR in HCC cells is unknown.This study aimed to explore the relationship between MDR and JNK in HCC cell lines with different degrees of MDR.METHODS:A MDR human HCC cell line,SMMC-7721/ ADM,was developed by exposing parental cells to gradually increasing concentrations of adriamycin.The MTT assay was used to determine drug sensitivity.Flow cytometry was used to analyze the cell cycle distribution and to measure the expression levels of P-glycoprotein(P-gp)and MDR-related protein(MRP)-1 in these cells.JNK1,JNK2 and JNK3 mRNA expression levels were quantified by real-time PCR.Expression and phosphorylation of JNK1,JNK2,and JNK3 were analyzed by Western blotting.RESULTS:The MDR of SMMC-7721/ADM cells resistant to 0.05 mg/L adriamycin was mainly attributed to the overexpression of P-gp but not MRP1.In addition,these cells had a significant increase in percentage in the S phase,accompanied by a decrease in percentage in the G0/G1 phase,which is likely associated with a reduced ability for cell proliferation and MDR generation.We found that JNK1,JNK2,and JNK3 activities were negatively correlated with the degree of MDR in HCC cells.CONCLUSION:This study suggests that JNK1,JNK2,and JNK3 activities are negatively correlated with the degree of MDR in HCC cells.

Influence of efflux pump inhibitors on the multidrug resistance of Helicobacter pylori

AIM:To evaluate the effect of efflux pump inhibitors (EPIs) on multidrug resistance of Helicobacter pylori (H. pylori).METHODS: H. pylori strains were isolated and cultured on Brucella agar plates with 10% sheep's blood. The multidrug resistant (MDR) H. pylori were obtained with the inducer chloramphenicol by repeated doubling of the concentration until no colony was seen, then the susceptibilities of the MDR strains and their parents to 9 antibiotics were assessed with agar dilution tests. The present study included periods before and after the advent of the EPIs, carbonyl cyanide m-chlorophenyl hydrazone (CCCP), reserpine and pantoprazole), and the minimum inhibitory concentrations (MICs) were determined accordingly. In the same way, the effects of 5 proton pump inhibitors (PPIs), used in treatment of H. pylori infection, on MICs of antibiotics were evaluated.RESULTS: Four strains of MDR H. pylori were induced successfully, and the antibiotic susceptibilities of MDR strains were partly restored by CCCP and pantoprazole, but there was little effect of reserpine. Rabeprazole was the most effective of the 5 PPIs which could decrease the MICs of antibiotics for MDR H. pylori significantly.CONCLUSION: In vitro, some EPIs can strengthen the activities of different antibiotics which are the putative substrates of the efflux pump system in H. pylori.

Biofilm formation in clinical isolates of nosocomial Acinetobacter baumannii and its relationship with multidrug resistance

Objective: To check biofilm formation by Acinetobacter baumannii(A. baumannii)clinical isolates and show their susceptibility to different antibiotics and investigate a possible link between establishment of biofilm and multidrug resistance.Methods: This study was performed on clinical samples collected from patients with nosocomial infections in three hospitals of Tehran. Samples were initially screened by culture and biochemical tests for the presence of different species of Acinetobacter. Identifications were further confirmed by PCR assays. Their susceptibilities to 11 antibiotics of different classes were determined by disc diffusion method according to Clinical and Laboratory Standards Institute guidelines. The ability to produce biofilm was investigated using methods: culture on Congo red agar, microtiter plate, and test tube method.Results: From the overall clinical samples, 156 specimens were confirmed to contain A. baumannii. The bacteria were highly resistant to most antibiotics except polymyxin B.Of these isolates, 10.26% were able to produce biofilms as shown on Congo red agar.However, the percentage of bacteria with positive biofilm in test tube, standard microtiter plate, and modified microtiter plate assays were 48.72%, 66.66%, and 73.72%, respectively. At least 92% of the biofilm forming isolates were multidrug resistant.Conclusions: Since most of the multidrug resistant strains produce biofilm, it seems necessary to provide continuous monitoring and determination of antibiotic susceptibility of clinical A. baumannii. This would help to select the most appropriate antibiotic for treatment.

Multidrug resistance associated proteins in multidrug resistance

Multidrug resistance proteins(MRPs) are members of the C family of a group of proteins named ATP-binding cassette(ABC) transporters.These ABC transporters together form the largest branch of proteins within the human body.The MRP family comprises of 13 members,of which MRP1 to MRP9 are the major transporters indicated to cause multidrug resistance in tumor cells by extruding anticancer drugs out of the cell.They are mainly lipophilic anionic transporters and are reported to transport free or conjugates of glutathione(GSH),glucuronate,or sulphate.In addition,MRP1 to MRP3 can transport neutral organic drugs in free form in the presence of free GSH.Collectively,MRPs can transport drugs that differ structurally and mechanistically,including natural anticancer drugs,nucleoside analogs,antimetabolites,and tyrosine kinase inhibitors.Many of these MRPs transport physiologically important anions such as leukotriene C4,bilirubin glucuronide,and cyclic nucleotides.This review focuses mainly on the physiological functions,cellular resistance characteristics,and probable in vivo role of MRP1 to MRP9.

Synergistic Effect of Hyperthermia and Neferine on Reverse Multidrug Resistance in Adriamycin-resistant SGC7901/ADM Gastric Cancer Cells

Multidrug resistance（MDR） plays a major obstacle to successful gastric cancer chemotherapy.The purpose of this study was to investigate the MDR reversal effect and mechanisms of hyperthermia in combination with neferine（Nef） in adriamycin（ADM） resistant human SGC7901/ADM gastric cancer cells.The MDR cells were heated at 42℃ and 45℃ for 30 min alone or combined with 10 μg/mL Nef.The cytotoxic effect of ADM was evaluated by MTT assay.Cellular plasma membrane lipid fluidity was detected by fluorescence polarization technique.Intracellular accumulation of ADM was monitored with high performance liquid chromatography.Mdr-1 mRNA,P-glycoprotein（P-gp）,γH2AX expression and γH2AX foci formation were determined by real-time PCR,Western blot and immunocytochemical staining respectively.It was found that different heating methods induced different cytotoxic effects.Water submerged hyperthermia had the strongest cytotoxicity of ADM and Nef combined with hyperthermia had a synergistic cytotoxicity of ADM in the MDR cells.The water submerged hyperthermia increased the cell membrane fluidity.Both water submerged hyperthermia and Nef increased the intracellular accumulation of ADM.The water submerged hyperthermia and Nef down-regulated the expression of mdr-1 mRNA and P-gp.The water submerged hyperthermia could damage DNA and increase the γH2AX expression of SGC7901/ADM cells.The higher temperature was,the worse effect was.Our results show that combined treatment of hyperthermia with Nef can synergistically reverse MDR in human SGC7901/ADM gastric cancer cells.

Reversal of multidrug resistance of hepatocellular carcinoma cells by metformin through inhibiting NF-κB gene transcription

AIM: To interfere with the activation of nuclear factor-κB(NF-κB) with metformin and explore its effect in reversing multidrug resistance(MDR) of hepatocellular carcinoma(HCC) cells.METHODS: Expression of P-glycoprotein(P-gp) and NF-κB in human HepG 2 or HepG 2/adriamycin(ADM) cells treated with pC MV-NF-κB-small interference RNA(siR NA) with or without metformin, was analyzed by Western blot or fluorescence quantitative PCR. Cell viability was tested by CCK-8 assay. Cell cycle and apoptosis were measured by flow cytometry and Annexin-V-PE/7-AnnexinV apoptosis detection double staining assay, respectively. RESULTS: P-gp overexpression in HepG 2 and HepG 2/ADM cells was closely related to mdr1 mR NA(3.310 ± 0.154) and NF-κB mR NA(2.580 ± 0.040) expression. NF-κB gene transcription was inhibited by specific siR NA with significant down-regulation of P-gp and enhanced HCC cell chemosensitivity to doxorubicin. After pretreatment with metformin, Hep G2/ADM cells were sensitized to doxorubicin and P-gp was decreased through the NF-κB signaling pathway. The synergistic effect of metformin and NF-κB siR NA were found in HepG 2/ADM cells with regard to proliferation inhibition, cell cycle arrest and inducing cell apoptosis. CONCLUSION: Metformin via silencing NF-κB signaling could effectively reverse MDR of HCC cells by downregulating MDR1/P-gp expression.

Effects of Taxotere on invasive potential and multidrug resistance phenotype in pancreatic carcinoma cell line SUIT-2

INTRODUCTIONDevelopment of drug-resistance to chemotherapyand subsequent metastasis of tumor are primarilyresponsible for treatment failure and the death fromcancer. There have been many previous studies onthe relationship between expression of multidrugresistance (MDR) phenotype P-glycoprotein (P-gp)and the malignant properties of tumors, but theresults are often conflicting[1-8]. The difference intumor types or MDR phenotype induced by specificagents might account for this discrepancy. Taxotere(TXT), a member of the family of taxanes, hasantitumor activity through its effect of promotingthe polymerization of tubulin[9,10].

Reversal of Multidrug Resistance and Inhibition of Phosphorylation of AKT in Human Ovarian Cancer Cell Line by Wild-type PTEN Gene

The reversing effect of wild-type PTEN gene on resistance of C 13K cells to cisplatin and its inhibitory effect on the phosphorylation of protein kinase B （AKT） were studied. The expression of PTEN mRNA and protein in OV2008 cells and C13K cells were semi-quantitatively detected by using RT-PCR and Western blotting. Recombinant eukaryotic expression plasmid containing human wild-type PTEN gene was transfected into C13K cells by lipofectamine2000. The expression of PTEN mRNA was monitored by RT-PCR and the expression of PTEN, Akt, p-Akt protein were ana- lyzed by Western blotting in PTEN-transfected and non-transfected C13K cells. Proliferation and chemosensitivity of cells to DDP were measured by MTT, and cell apoptosis was detected by flow cytometry after treatment with cisplatin. The expression of PTEN mRNA and protein in OV2008 cells were significantly higher than those in C13K cells. After transfection with PTEN gene for 48 h, the expression of PTEN mRNA and protein in C 13K cells were 2.04 ± 0.10, 0.94± 0.04 respectively and the expression of p-Akt protein （ 0.94± 0.07） was lower than those in control groups （1.68 ±0.14, 1.66± 0.10） （P〈 0.05）. The IC50 of DDP to C 13 K cells transfected with PTEN （7.2± 0.3 la mol/L） was obviously lower than those of empty-vector transfected cells and non-transfected cells （12.7±0.4 lamol/1, 13.0±0.3 lamol/L） （P〈0.05）. The apopototis ratio of wild-type PTEN-transfected, empty vector transfected and non-transfected C13K cells were （41.65___0.87）%, （18.61 ±0.70）% and （15.28±0.80）% respectively, and the difference was statistically significant （P〈0.05）. PTEN gene plays an important role in ovarian cancer multidrug resistance. Transfection of PTEN could increase the expression of PTEN and restore drug sensitivity to cisplatin in human ovarian cancer cell line C 13K with multidrug-resistance by decreasing the expression of p-Akt.

Correlative Expression of Glutathion S-Transferase-π and Multidrug Resistance Associated Protein in Bladder Transitional Cell Carcinoma

In order to elucidate the mechanisms of multidrug resistance (MDR) in bladder cancer, the expression of glutathione S-transferase-π (GST-π) and multidrug resistance associated protein (MRP) in tissue samples resected from 44 patients and 6 normal bladder mucosa as control was de- tected by using immunohistochemical method, and the results were analyzed by computer-assisted im- age analyzing system (IAS) to achieve semi-quantitative data. In addition, correlation between the expression of both factors was studied. The results showed that the positive expression rate of GST- π and MRP in bladder cancer was 72. 7 % (32/44) and 68. 2 % (30/44) respectively, significantly higher than those in normal bladder mucosa, being 16. 7% and 33. 3% respectively. The rate of GST-πpositive staining was increased correspondingly with tumor grade and stage elevated, being higher in recurrent tumors treated by chemotherapy, but not significantly (P>0. 05). There was no significant differences between the expression of MRP and tumors' behaviors and clinical characters. However, the results demonstrated that the correlation between the expression of both resistant fac- tors was very evident (r=0. 695, P<0. 0025). It was suggested that the activation of GST-π and MRP might occur during malignant transformation of normal mucosa, but tumors' differentiation and progression could not be the unique factors that influenced both overexpression. Chemotherapy might be another important reason. The correlation of both indicated that there was a common mech- anism regulating their expression probably, which made them play a pivotal role in chemotherapy drug resistance of bladder cancers.