ALBERT

Description: Objective: To prepare functionalized Fe3O4-magnetic nanoparticles(Fe3O4-MNPs) loaded with adriamycin(ADM) or Fe3O4-MNPs co-polymerized with ADM and tetrandrine(Tet) to investigate whether the temperature, time or ratio of drug to nanoparticles influences the polymerization. To study the reversal role that the drug-loaded nano-composites play in K562 and one of its resistant cell line K562/A02 and to learn the reversal mechanism of this kind of treatments so as to provide theoretic evidence for the clinical application of them as resistance modifying agents. Method: The drug-loaded nanoparticles were prepared using mechanical absorption polymerization process in different condition of 4° or 37° for 24h or 48h. To investigate whether Fe3O4-MNPs loaded with ADM and Tet would play a synergetic reverse role in multidrug resistant cell, the drug-loaded nanoparticles by mechanical absorption polymerization were prepared to act with K562 and one of its resistant cell line K562/A02. The survival of cells which were cultured with drug-loaded nano-composites for 48h was observed through MTT assay, the growth inhibition efficacy of cells was calculated then. Using cells under the same condition described before, we took use of fluorescence microscope to measure fluorescence intensity of intracellular ADM at a wavelength of 488nm. P-glycoprotein (P-gp) was analyzed with flow cytometer. The expression of mdr1 mRNA was measured by RT-PCR. Results: The results showed that the growth inhibition efficacy of both the two cells increased with augmenting concentration of Fe3O4-MNPs which were loaded with drugs. The condition of 4° and 48h was significantly better than that of 37° and 24h respectively. Both Fe3O4-MNPs loaded with ADM or Fe3O4-MNPs co-polymerized with ADM and Tet elevated the intracellular ADM accumulation in K562/A02. However, no linear correlation was found between fluorescence intensity of intracellular adriamycin and augmenting concentration of Fe3O4-MNPs in K562/A02. Tet could downregulate the level of mdr-1 gene and decrease the expression of P-gp. Furthermore, Tet polymerized with Fe3O4-MNPs reinforced this downregulation, causing a 100-fold more decrease in mdr1 mRNA level, but did not reduce total P-gp content. Conclusions: Fe3O4-MNPs can load ADM or both ADM and Tet by mechanical absorption polymerization, which depends on proper temperature and time. Furthermore, the drug-loaded nano-composites have the ability in multidrug resistance reversal. Fe3O4-MNPs loaded with ADM or Tet can enhance the effective accumulation of the drugs in K562/A02 and Fe3O4-MNPs loaded with Tet obviously reverse multidrug resistance by reinforcing mdr1 gene downregulation. Functionalized Fe3O4-MNPs loaded with Tet probably have synergetic effect on reversal in multidrug resistance.

Description: Objective: This paper was to study the reversal effect of magnetic Nano-Fe3O4 or Nano-Au with DNR, on multidrug resistance cell line K562/A02 and to investigate the reversal mechanism of this combination, and to provide theoretic evidence for the clinical application of them as resistance modifying agents. Method: The IC50 (the concentration causing 50% inhibition of cell growth) of DNR, Nano-Fe3O4 and Nano-Au respectively were assayed by MTT method.The drug-loaded nanoparticles were prepared by solvent diffusion method.Some nanoparticales, volume ratio from 1.5% to 50%, were combined with some DNR to find the best combination to prepare best drug-loaded nanopartilces.At last, the K562/A02 cells was treated with the composite of 25% nanoparticales and 10mg/L DNR, which MDR1 mRNA was assayed by RT-PCR;intracellular drug concentration and the apoptosis was determined by fluorometry and confocal fluorescence microscope. Results: The IC50 of DNR for K562/A02 and K562 cells were 23.23mg/L and0.307mg/L respectively.Two nanoparticles themselves have not evident cytotoxic effect to K562/A02 and K562 cells.Pretreating K562/A02 cells with the composite of 25% nanoparticales and 10mg/L DNR for 48 hours partially restored the sensitivity of K562/A02 cells to DNR;K562/A02 showed apoptotic characteristics after treated with this composite;drug-loaded nanopartilces elevated the intracellular DNR accumulation in K562/A02 and its MDR1 mRNA were down regulated.Data was analyzed by SPSS 11.5 software and expressed as mean ± SD. Conclusions: Nano- Fe3O4 or Nano-Au can increases the intracellular free DNR concentration of the K562/A02 cells, which lead to more K562/A02 cells apoptosis. Two nanoparticles themselves could not lower the MDR1 gene expression of the K562/A02 cells, but they degraded the MDR1 gene level with combine DNR. These results suggested that Nano- Fe3O4 or Nano-Au with DNR can reverse the resistance of K562/A02 cells significantly.

Description: Objective: The aim of this study was to investigate the mechanism to reverse the drug resistance of leukemia cells in Cyclosporine A(CsA), tetrandrine (Tet) alone or their combination by using empirical methods, and to provide the basic evidence for further study, and lay the theoretical basis for the clinical applications. Method: By MTT assay, the IC50(the concentration causing 50% inhibitor of cell growth) of DNR was determined;By flow cytomet ry (FCM) assay, the intracellular DNR concentration and the expression of P-glyco-protein (P-gp) were examined, and the apoptotic changes were observed by Anexin-V. By fluorescent semi-quantitative reverse transcriptase polymerase chain reaction (RT-PCR), the mRNA expression of multidrug resistance (MDR) was measured. Results: The IC50 of DNR for K562 and K562/A02 cells were 0.26mg/l and 21.22mg/l respectively. Treating K562/A02 cells with CsA(1mg/L), TTD(0.1mg/L)and both for 48 hours partially restored the sensitivity of K562/A02 cells to DNR(IC50 were 7.83 mg/L,5.32 mg/L,2.33 mg/L respectively.) but had not effect on K562 cells; K562/A02 cells showed apoptotic characteristics after treated with CsA, and both for 48 hours(Apoptosis rate was 10.27%,17.64%,52.79% respectively); The fluorescence intensity of intracellelar DNR in K562 and K562/A02 cells treated with DNR(1mg/L)was 522,173 respectively. CsA and TTD (alone or combination) elevated the intracellular DNR concentration in K562/A02 cells(the fluorescence intensity of intracellelar DNR in K562/A02 cells was 188,339,515 respectively); The fluorescence intensity of P-gp in K562 and K562/A02 cells was 0.5,97.97. The P-gp expression was down after treated with CsA, TTD and both(73.7,65.05,58.1); mdr1 mRNA was also down regulated, and the effect of their combination was greater. Date was analyzed by SPSS 13.0 software and expressed as mean ± SD. Conclusions: High expression of P-gp may be involved in the mechanism of multidrug resistance (MDR) of K562/A02 cells line; MDR can be partially reversed by CsA or TTD, of which the combination shows a great synergistic reversal effect.

Description: Objective: The present study aimed to evaluate the MDR reversal activity of bromotetrandrine (BrTet), a bromized derivative of tetrandrine (Tet), in vitro. Methods: Drug sensitivity was determined using the MTT assay. Adriamycin (ADM) accumulation, the protein levels of P-glycoprotein (P-gp) and the apoptotic changes were analyzed by fluorospectrophotometry, respectively. The mRNA levels of P-gp was determined by RT-PCR. Results: BrTet at 0.25, 0.5 and reversed ADM resistance in MDR K562/A02 cells dose-dependently and its potency was greater than that of Tet at the same concentrations. The IC50 of ADM for K562 and K562/A02 cells were 55.122 mg/l and 1.1373 mg/l, respectively. Treating K562/A02 cells with BrTet(1uM)and TTD(1uM)both for 48 hours partially restored the sensitivity of K562/A02 cells to ADM (IC50 were 4.7729 mg/l and 13.584 mg/l respectively) but had not effect on K562 cells. The fold reversal (FR) were 11.55 and 4.06 respectively. K562/A02 cells showed apoptotic characteristics after treated with Brtet and Tet both for 48 hours compared with control group(apoptosis rate was 61.1%, 11.1% and 9.9%,respectively); Fluorospectrophotometric assay showed that BrTet significantly increased the intracellular accumulation of ADM in K562/A02 cells in a dose-dependent manner. The fluorescence intensity of intracellelar ADM in K562/A02 cells treated with ADM(1mg/L)was 33% of that in K562 cells. BrTet and Tet elevated the intracellular ADM concentration in K562/A02 cells up to 52% and 69%,respectively. BrTet also inhibited the overexpression of P-gp in K562/A02 cells. The fluorescence intensity of P-gp in K562 and K562/A02 cells was 0.5 and 97.97.The P-gp expression was down after treated with BrTet and TTD (65.05 and 54.86). The mdr1 mRNA was also down regulated. Conclusions: BrTet showed significant MDR reversal activity in vitro. Its activity may be related to the inhibition of P-gp overexpression and the increase in intracellular accumulation of anticancer drugs. BrTet may be a promising MDR modulator for eventual assessment in the clinic.