Development Of Liposomal Pemetrexed For Enhanced Therapy Against Multidrug Resistance Mediated By ATP-binding Cassette Sub-family C,Member 5(ABCC5) In Breast Cancer

Objective: To prepare the liposomal pemetrexed and investigate its effects on MCF-7 breast cancer cells in vitro and nude mice bearing MCF-7 xenograft tumors in vivo,if it could overcome breast cancer multidrug resistance mediated by ATP-binding cassette sub-family C,member 5(ABCC5).Methods: The liposomes were prepared by film dispersion method and the characteristics were measured.In vitro,MCF-7 cells uptake of pemetrexed or liposomal pemetrexed was performed by the laser scanning confocal microscope.Inhibition of pemetrexed and liposomal pemetrexed to MCF-7 breast cancer cell lines or MCF-7 cells transfected with adenoviruses containing multidrug resistant gene ABCC5(MCF-7+ABCC5)was evaluated by Cell Counting Kit-8(CCK-8)method,Hoechst 33342 staining method,flow cytometry(FCM)and Western blot.The xenograft tumor models were established in Balb/c nude mice and adenoviruses were injected into the tumors.The drug was injected by tail vein to evaluate its anti-tumor effects.Then in vivo fluorescence imaging was performed on mice.Results: The size,zeta potential,PDI,EE%,drug loading and vitro release rate of 48 h were 160.77 nm,-1.40 m V,0.08,2.54mg/ml,63.5% and 76.22% respectively.The confocal studies showed that,compared to pemetrexed,liposomal pemetrexed was more likely to be taken by MCF-7 cells.The CCK-8 experiment showed that the IC50(half maximal inhibitory concentration)values of pemetrexed and liposomal pemetrexed on MCF-7 cells were 0.167 and 0.066 μg/ml respectively,whereas those of the two drugs on MCF-7+ABCC5 were 0.370 and 0.145 μg/ml respectively.Hoechst 33342 method,FCM and Western blot method showed that compared to pemetrexed,liposomal pemetrexed had stronger inhibition function on cell lines.Compared with blank group(same volume of PBS),the volume and weight of tumors of nude mice in experiment group(liposomal pemetrexed)and control group(same volume of pemetrexed)were significantly lower,and the volumes and weight of tumors in experiment group were also significantly lower than that in control group(p<0.05).And in vivo fluorescence imaging studies indicated that 24 h after injection,liposomes tended to targeted around tumors.Conclusion: Compared to pemetrexed,liposomal pemetrexed can inhibit the growth of MCF-7 breast cancer cells and the nude mice bearing MCF-7 xenograft tumors.In addition,it could be a potential way to overcome breast cancer multidrug resistance mediated by ABCC5.