OBJECTIVE In this study, we applied multidrug resistant leukemia cell line expressing mdr1-mRNA to observe changes in mdr1-mRNA, the P-gp, cell cycle and apoptosis before and after bortezomib was used, in order to exp...OBJECTIVE In this study, we applied multidrug resistant leukemia cell line expressing mdr1-mRNA to observe changes in mdr1-mRNA, the P-gp, cell cycle and apoptosis before and after bortezomib was used, in order to explore the mechanism of reversal of leukemia multidrug resistance by the proteasome inhibitor bortezomib.METHODS Flow cytometry （FCM） was used to detect the intracellular drug concentration, expression of P-gp, cell apoptosis and cell cycle status of K562/DNR cells before and a er treatment with different concentrations of bortezomib. Fluorescence quantitative PCR was applied to detect the mdr1-mRNA expression in K562/DNR and K562/S cells.RESULTS Bortezomib could increase the intracellular DNR content in K562/DNR cells, but showed no e. ect in K562/S cells.5-100 nmol/L bortezomib could significantly reduce the P-gp/mdr1-mRNA expression in K562/DNR cells in vitro, and showed a dose-dependent effect. There was a statistically significant di. erence （P 〈 0.05） between di. erent concentration groups and the control group. P-gp/mdr1-mRNA expression was negatively correlated with cell apoptosis （r = -0.912 and P 〈 0.01）. After treatment with different concentrations of bortezomib for 24 h,K562/DNR cells in G2 ＋ M phases were significantly increased,while cells in G0 ＋ G1 phases and S phase were significantly decreased, accompanied by an increased apoptotic rate.CONCLUSION Bortezomib can induce G0 ＋ G1 phase to G2 ＋ M phase, and thereby enhance the chemosensitivity of leukemia, and may also reverse the multidrug resistance in leukemia mediated by P-gp overexpression encoded by mdr1 gene. This confi rms that bortezomib can reverse leukemia multidrug resistance at the levels of nucleic acid and protein molecules.展开更多
Pseudomonas aeruginosa is an opportunistic pathogen that contributes to high morbidity and mortality. MexAB-OprM is the main efflux pump among the Resistance-Nodulation-Division family multi-drug effiux systems, which...Pseudomonas aeruginosa is an opportunistic pathogen that contributes to high morbidity and mortality. MexAB-OprM is the main efflux pump among the Resistance-Nodulation-Division family multi-drug effiux systems, which contribute greatly to the multidrug resistance of P. aeruginosa. Effiux pump inhibitors （EPIs） of MexAB-OprM could enhance the activity of the antibiotics effiuxed by MexAB-OprM, and thus they might be useful in the clinic as antibacterial synergistic agents. In this work, a new EPI of MexAB-OprM, KL-0153, was discovered by screening of a small molecular library. Its inhibition of MexAB-OprM was confirmed by assays of synergistic activity and EB accumulation. The activity of KL-0153 was shown to be synergistic with antibiotics effiuxed by MexAB-OprM when they were tested against strains expressing MexAB-OprM, especially so for the strains that express MexAB-OprM at high levels. KL-0153 showed more activity than the positive drug carbonyl cyanide m-chlorophenylhydrazone in the EB accumulation assay. It cannot be neglected that KL-0153 has significant liver and kidney toxicity. However, KL-0153 may be a lead comoound for the research and development of new tvoes of EPIs.展开更多
文摘OBJECTIVE In this study, we applied multidrug resistant leukemia cell line expressing mdr1-mRNA to observe changes in mdr1-mRNA, the P-gp, cell cycle and apoptosis before and after bortezomib was used, in order to explore the mechanism of reversal of leukemia multidrug resistance by the proteasome inhibitor bortezomib.METHODS Flow cytometry （FCM） was used to detect the intracellular drug concentration, expression of P-gp, cell apoptosis and cell cycle status of K562/DNR cells before and a er treatment with different concentrations of bortezomib. Fluorescence quantitative PCR was applied to detect the mdr1-mRNA expression in K562/DNR and K562/S cells.RESULTS Bortezomib could increase the intracellular DNR content in K562/DNR cells, but showed no e. ect in K562/S cells.5-100 nmol/L bortezomib could significantly reduce the P-gp/mdr1-mRNA expression in K562/DNR cells in vitro, and showed a dose-dependent effect. There was a statistically significant di. erence （P 〈 0.05） between di. erent concentration groups and the control group. P-gp/mdr1-mRNA expression was negatively correlated with cell apoptosis （r = -0.912 and P 〈 0.01）. After treatment with different concentrations of bortezomib for 24 h,K562/DNR cells in G2 ＋ M phases were significantly increased,while cells in G0 ＋ G1 phases and S phase were significantly decreased, accompanied by an increased apoptotic rate.CONCLUSION Bortezomib can induce G0 ＋ G1 phase to G2 ＋ M phase, and thereby enhance the chemosensitivity of leukemia, and may also reverse the multidrug resistance in leukemia mediated by P-gp overexpression encoded by mdr1 gene. This confi rms that bortezomib can reverse leukemia multidrug resistance at the levels of nucleic acid and protein molecules.
文摘Pseudomonas aeruginosa is an opportunistic pathogen that contributes to high morbidity and mortality. MexAB-OprM is the main efflux pump among the Resistance-Nodulation-Division family multi-drug effiux systems, which contribute greatly to the multidrug resistance of P. aeruginosa. Effiux pump inhibitors （EPIs） of MexAB-OprM could enhance the activity of the antibiotics effiuxed by MexAB-OprM, and thus they might be useful in the clinic as antibacterial synergistic agents. In this work, a new EPI of MexAB-OprM, KL-0153, was discovered by screening of a small molecular library. Its inhibition of MexAB-OprM was confirmed by assays of synergistic activity and EB accumulation. The activity of KL-0153 was shown to be synergistic with antibiotics effiuxed by MexAB-OprM when they were tested against strains expressing MexAB-OprM, especially so for the strains that express MexAB-OprM at high levels. KL-0153 showed more activity than the positive drug carbonyl cyanide m-chlorophenylhydrazone in the EB accumulation assay. It cannot be neglected that KL-0153 has significant liver and kidney toxicity. However, KL-0153 may be a lead comoound for the research and development of new tvoes of EPIs.
