RESUMO
Multi-drug resistance(MDR)refers to the loss of sensitivity of tumor cells to traditional chemotherapeutics agents under the mediation of various mechanisms,resulting in the reduction of chemotherapy efficacy.Current studies suggest that a variety of factors,including cell membrane transporter-mediated efflux of anti-tumor drugs,special microenvironment in tumor tissue,DNA self-repair and anti-apoptotic process,and epithelial-mesenchymal cell transformation,may contribute to the formation of MDR.Cell membrane transporter-mediated drug efflux refers to an increase in the amount of anti-tumor drug pumped out of the cell through the up-regulation of the ATP-binding cassette transporter on tumor cell membrane,which reduces the concentration of the drug in the cell,thus forming MDR.An effective method to inhibit the efflux pump caused by overexpression of membrane transporters plays an important role in overcoming MDR.As a promising drug delivery system,multifunctional nanoparticles have demonstrated many advantages in antitumor therapy.Meanwhile,nanoparticles with tailored design are capable of overcoming MDR when combined with a variety of strategies.This paper described in detail the studies relevant to the use of multifunctional nano-sized drug delivery system combined with different strategies,such as co-delivery of agents,external responsiveness or target modification for intervention with efflux pump in order to reverse MDR.This paper provides reference for the development of nano-sized drug delivery system and the formulation of reversal strategy in the future.