Overcoming Drug-resistant Lung Cancer By Paclitaxel Loaded Dual-functional Liposomes With Mitochondria Targeting And Ph-response

Malignant tumor is one of the major diseases that endanger human life and health.The current strategies for tumor treatment include chemotherapy,radiation therapy,immunotherapy and surgical treatment,but none of these are effective enough,and the development of multidrug resistance(MDR)makes tumor treatment more difficult.Thus,it is one of the most urgent and challenging work to develop safe and efficient drug delivery systems to inhibit and overcome MDR.Smart liposomes that are responsive to the microenvironment of tumor tissue have been utilized to enhance chemotherapeutic efficiency.Here,we reported a novel liposome,which has a pH response,to enhance drug accumulation in tumor sites and intercellular uptake.L-lysine was used as a linker to connect 2,3-dimethylmaleic anhydride(DMA)and 1,2-distearoyl-sn-glycero-3-phosphoethanolamine(DSPE)to yield a DSPE-Lys-DMA(DLD)lipid.The pH-responsive DLD was mixed with other commercially available lipids to form liposomes.The size,morphology and zeta potential of the DLD liposomes(DLD-Lip)were measured.Paclitaxel(PTX)was loaded in the liposomes.The release profile,cellular uptake,in vitro and in vivo anticancer activity of the PTX-loaded liposomes were investigated.The results showed that the mean diameter of the liposomes was less than 200 nm.The zeta potential of the liposomes was negative at pH 7.4.However,it was transferred to positive at weak acidic pH values with the cleavage of DMA amide.The charge reversion of DMA in acidic environments facilitated the cellular internalization and endosome escape of DLD-Lip,which inhibited the proliferation of 4T1 cancer cells in vitro.The pH-responsive liposomes also exhibited efficient anticancer activity in the xenograft breast cancer model in vivo.Mitochondrion-orientated transportation of smart liposomes has been developed as a promising strategy to deliver anticancer drugs directly to tumor sites,and these have a tremendous potential for killing cancer cells,especially those with multidrug resistance(MDR).Herein we report a novel dual-functional liposome system possessing both extracellular pH response and mitochondrial targeting properties to enhance drug accumulation in mitochondria and trigger apoptosis of drug-resistant cancer cells.Briefly,peptide D[KLAKLAK]2(KLA)was modified with 2,3-dimethylmaleic anhydride(DMA)and combined with 1,2-distearoyl-sn-glycero-3-phosphoethanolamine(DSPE)to yield a DSPE-KLA-DMA(DKD)lipid.This dual-functional DKD was then mixed with other commercially available lipids to fabricate liposomes.In vitro anticancer efficacy of this liposome system was evaluated in human lung cancer A549 cells and drug-resistant lung cancer A549/Taxol cells.At tumor extracellular pH(?6.8),liposomes could reverse their surface charge(negative to positive),facilitating liposome internalization.After cellular uptake,KLA peptide directed delivery-enabled selective accumulation of these liposomes into mitochondria and favored release of their cargo paclitaxel(PTX)into desired sites.Specifically,enhanced apoptosis of MDR cancer cells through mitochondrial signaling pathways was evidenced by release of cytochrome c and increased activity of caspase-9 and caspase-3.These dual-functional liposomes had the greatest efficacy for treating A549 cells and A549/Taxol cells in vitro,and in treating drug-resistant lung cancer A549/Taxol cells xenografted onto nude mice(tumor growth inhibition 86.7%).In conclusion,dual-functional liposomes provide a novel and versatile approach for overcoming MDR in cancer treatment.