Application Of New Nano - Drug Carrier In Reversing The Drug Resistance Of Tumor Cells

Objective Breast cancer is a common cancer that seriously threatens women’s health. Inspiteof considerable advancements in early detection as well as therapeutic strategies, the mortality of breast cancer patients remains high. A main obstacle to more effective treatments for this disease is that cancer cells become resistant to one or more anticancer drugs. Multidrug resistance (MDR) greatly reduces cytotoxicity of chemotherapy drugs on cancer cells and is responsible for the failure of 90% of chemotherapy in late stage disease. Quercetin is a natural flavonoid compound that has attracted increasing interest due to its function of reversal of drug resistance. Yet, the major hurdle in its clinical usage is the drug’s poor water solubility and absorption. Thus, alternative strategies based on the use of efficient delivery system stable in aqueous solution have been undertaken to improve the water solubility and the bioavailability of quercetin so as to improve its biological activity. Polymeric micelles prepared from amphiphilic copolymers combining hydrophilic and hydrophobic blocks have attracted much attention in recent years. Polymeric micelles have many excellent properties including the high stability in vitro and in vivo and the encapsulation of poorly soluble drugs. The micelles prepared from polyethyleneglycol conjugated phosphatidylethanolamine (PEG-PE), a component approved by the U.S. Food and Drug Administration (FDA) for human application, have good biocompatibility and safety profiles. So far, however, PEG-PE micells have not been used to encapsulate quercetin to reverse MDR. In this study, we constructed PEG-PE micelles encapsulating quercetin to explore whether quercetin-loaded PEG-PE micelles (M-Q) will synergize the growth-inhibitory activity of adriamycin (ADR) by reversing the drug resistance of MCF-7 ADRr breast cancer cells in vitro.Methods Quercetin was dissolved in ethanol and PEG-PE was dissolved in chloroform. Mix up quercetin with PEG-PE in different concentration ratios. The mixed solution was evaporated in a nitrogen atmosphere to form a layer of dry film. M-Q was formed by adding saline to lipid film containing quercetin and PEG-PE. The size and Zeta potential of M-Q was characterized by dynamic light scattering (DLS). The encapsulation efficiency of quercetin was tested by ultraviolet spectrophotometry. The inhibition of MCF-7 ADRr cells was evaluated by MTS assay after incubation with M-Q and ADR. In order to assess the influence of PEG-PE micelles alone on target cells, MCF-7 ADRr cells were also incubated with PEG-PE micelles solution of various concentrations for 72 hours and the cell viability was measured.by MTS assay.Results (1)The average size of M-Q was 11.11nm which is similar with the blank micelles revealed by dynamic light scattering (DLS), the Zeta potential of blank micelles and M-Q was -0.165mV and -0.406mV, respectively. (2) PEG-PE micelles could encapsulate quercetin effectively and the incorporation efficiency of quercetin by the micelles was above 74%. (3) Compared with the quercetin dissolved in ethanol, M-Q more effectively reversed the drug resistance of MCF-7 ADRr cells in vitro(p<0.05). (4) The safety of the PEG-PE micelles used in this study was good and the results of the MTS assay showed that the PEG-PE micelles had no influence on the viability of MCF-7 ADRr cells through a range of concentration from 15μmol/L to 120μmol/L.Conclusions M-Q is capable of reversing the drug resistance of MCF-7 ADRr cells effectively in vitro and the reverse effect of M-Q is significantly superior to the free quercetin. Thus, PEG-PE micelles may have potential for delivering quercetin to cancer cells for reversal of drug resistance.Objective Lung cancer is the most common malignancy worldwide. Of all the malignant tumors, the morbidity and mortality of lung cancer comes the 巧rst in men,and the second in women. In recent years, the mortality rate of lung cancer continues!:〇 rise. Unfortunately,the 5-year survival rate is less than 150/0 even after the treatment.Chemotherapy is one of the main methods fbr treating late-stage lung cancer, but the efficacy is not as ideal as expected. Multidrug resistance(MDR) is the key contributin吕 factor which results in the failure of lung cancer chemotherapy. In order to overcome MDR in cancer cells,people have been exploring new nano drug delivery systems t:o improve the sensitivity of cancer cells to chemotherapy drugs.DNA nanol:echnology has gradually become rtie hot spot of the nanomedicine. The rapid development of DNA nanotechnology makes DNA a versatile material which is widely used. Through the use of base painng rules, a large number of different geometric structures of DNA nanoconstructs can be designed and prepared. Among them, the DNA tetrahedron has been considered one of the most practical DNA nanoconstracts since it can be sdf-assembled simply from four DNA strands and prepared in a high yield. So far,however, DNA ththahedrons have not been used to encapsulate adriamydn(ADR) reverse the drug resistance of lung cancer cells. Inthis study, we constructed ADR-loaded DNA thtrahedrons using tile self-assembly character of the DN乂 tetrahedron and the ADR binding property of DNA 1:0 explore whether ADR-loaded DNA tetrahedrons will synergize the growth-inhibitory activity of AD R by reversing the drug resistance of A549 ADRr lun g can cer cells in vitro.Methods Four DNA strands(A,B,C and D) were dissolved in TE buffer.The same quantity of each strand was mixed with TM buffer,也en the mixture was heated th95 〇C for 2 min and cooled in ice bathto construct DNA tetrahedron. In order thdemonstrate the assembling of DNA tetrahedron, agarosegel electrophoresis was applied. Different molar ratios of mixed DNA tetrahedron and ADR were put in the black 96-well assay plate. When ADR folly embedded into DNA tetrahedron,theADR-loaded DNA tetrahedron was C0nstructed0 analysis the AD反-loading rate ofthe DNA tetrahedron, we applied fluorescence spectrum analyzer detect the fluorescence spectrum of ADR. The si之e and Zeta potential of DNA tetrahedron was characterized by dynamic light scattering(DLS). The inhibition of A549 ADRr cells was evaluated by MTS assay after incubation with ADR-loaded DNA tetrahedron. In order to assess the influence of DNA tetrahedron alone on target cells,A549 ADRr cells were also incubated witti DNA tetrahedron solution of various COncentrations fbr48 hours and the cell viability was measured by MTS assay.Results(l)DNA tetrahedron moved more slowly than any otiher combmations lacking0ne or two strands(A+B、A+B+C) in agarose gel electrophoresis imaging. 口)The average size of DNA tetrahedron was 13.81 nm and the Zeta potential of DNAthtrahedron was-0.427 mV revealed by dynamic light %attering(DLS)(3)The fluorescence spectrum of adriamycin detected by fluorescence spectrum analyzer demonstrated that DNA tetrahedron could load ADR effectively.(4) The results of the MTS assay showed that when the concentration of ADR was above 15^imol/L,ADR-loaded DNA tetrahedron could synergize the growth-inhthitory activity of ADRby reversing rtie drug resistance of A549 ADRr cells in vitro(p<0.05). DNAthtrahedron per se had no influence on th6 viability of A549 ADRr cells.Conclusions ADR-loaded DNA tetrahdrornnay contribute to reversing 比e drug resistance of A549 ADRr cells in vitro. Thus, as a new nano drug delivery system,DNA tetrahedron may have potential fbr delivering ADR to cancer cells fbr reversal of drug resistance.