Research Of Liposomes On Overcoming Multidrug Resistance Of Tumor Cells

Multiple administration of chemotherapy drugs would cause multidrug resistance of tumor cells.Since the multidrug resistance of tumor cells retards therapeutic effect of malignant tumors,the mortality rate of cancer patients is constantly high.With social development,people begin to pay more attention to cancer patients,and new treatment methods and drugs to extend the survival time of cancer patients are strongly needed.At present,one of the most important problems in malignant tumors is to find a way to overcome the multidrug resistance of the tumor cells.Due to excellent biodegradability and biocompatibility,liposomes are often used as drug nanocarriers clinically.Thus,liposomes are promising carriers of drugs and genes on overcoming multidrug resistance of ovarian cancer cells.In this paper,in order to solve the problem of multidrug resistance of tumor cells,liposomes as nanocarriers for drug and gene delivery system are designed in two aspects: direct inhibition of drug efflux protein on the cell membrane and direct inhibition of expression of multidrug resistance gene.We co-deliver the inhibitor tariquidar of the drug efflux protein on the cell membrane and doxorubicin by pH-sensitive liposomes to overcome the multidrug resistance of ovarian cancer cells.Specifically,after multiple trials,we successfully constructed pHSL/TQR1/ DOX0.05(the DOX loading rate is 5%,TQR loading rate is 1%,particle size is 144 ± 7nm,and the Zeta potential is-28.1 ± 0.7mV).The in vitro tests show that the liposome exhibits excellent pH-sensitive release properties.Cellular experiments show that the liposome is able to efficiently deliver DOX into the OVCAR8/ADR cells.The pHSL/TQR1/DOX0.05 is able to effectively inhibit the proliferation of OVCAR8/ADR cells.When the concentration of DOX is 8.0 ?g/mL,the cell viability of OVCAR8/ADR cells after incubation with pHSL/TQR1/DOX0.05 is 6.6%,while that of OVCAR8/ADR cells after incubation with pHSL/DOX0.05 and free DOX solution as control are 64.0% and 43.5%,respectively.Meanwhile,the cell viability of OVCAR8 cells after incubation with free DOX solution is 7.3%.By comparing with the control group and the drug sensitive cells of OVCAR8,pHSL/TQR1/DOX0.05 almost completely overcomes the drug resistance of OVCAR8/ADR cells.It implies that TQR can efficiently inhibit the efflux of DOX.Meanwhile,the toxicity of pHSL/TQR is very low.Therefore,low carrier toxicity and high tumor cell inhibition make the pHSL/TQR1/DOX0.05 be apromising composite nanocarrier on overcoming multidrug resistance of tumor cells.To reduce the expression of multidrug resistance(MDR)gene,we delivered CRISPR-Cas9 plasmid by constructing lipid/polymer/DNA(LPD)complexes.In this way,we hopefully improve the drug sensitivity of drug-resistant tumor cells.By encapsulating complexes of GFP plasmid and polyethylenimine(branched 25kDa)into cationic liposomes,the LPD is successfully synthesized.The particle size of the cationic liposome is 117 ± 6 nm and the Zeta potential is 43.4 ± 0.8 mV.When the charge ratio of Liposome/PEI/DNA in LPD is 1: 0.8: 1,the transfection efficiency of LPD to transfect GFP plasmid in 293 T cells is 92.7%,while that of the positive control Lipofectamine2000 is 97.8%.However,LPD can not efficiently transfect CRISPR-Cas9 plasmid into drug-resistant cells OVCAR8/ADR and MCF7/ADR.After performing the positive control experiments,we analyzed that the reason of low transfection efficiency of CRISPR-Cas9 plasmid in ADR cells could be that the drug-resistant cells themselves are not appropriate for plasmid transfection.