A Mechanistic Study of Enhanced Doxorubicin Uptake and Retention in Multidrug Resistant Breast Cancer Cells Using a Polymer-Lipid Hybrid Nanoparticle System

Abstract

The objectives of this study were to evaluate the potential of a polymer-lipid hybrid nanoparticle (PLN) system to enhance cellular accumulation and retention of doxorubicin (Dox), a widely used anticancer drug and an established P-glycoprotein (Pgp) substrate, in Pgp-overexpressing cancer cell lines and to explore the underlying mechanisms. Nanoparticles containing Dox complexed with a novel anionic polymer (Dox-PLN) were prepared using an ultrasound method. Two Pgp-overexpressing breast cancer cell lines (a human cell line, MDA435/LCC6/ MDR1, and a mouse cell line, EMT6/AR1) were used to investigate the effect of nanoparticles on cellular uptake and retention of Dox. Endocytosis inhibition studies and fluorescence microscopic imaging were performed to elucidate the mechanisms of cellular drug uptake. Treatment of Pgp-overexpressing cell lines with Dox-PLNs resulted in significantly enhanced Dox uptake and more substantial increases in drug retention after the end of treatment compared with free Dox solutions (p Ͻ 0.05). Fluorescence microscopic images showed improved nuclear localization of Dox and uptake of lipid when the drug was delivered in the Dox-PLN form to MDA435/LCC6/ MDR1 cells. Endocytosis inhibition studies revealed that phagocytosis is an important pathway in the membrane permeability of the nanoparticles. These findings suggest that some of the Dox physically associated with the nanoparticles bypass the membrane-associated Pgp when delivered as DoxPLNs, and in this form, the drug is better retained within the Pgp-overexpressing cells than the free drug. The present study suggests a new mechanism for overcoming drug resistance in Pgp-overexpressing tumor cells using lipid-based nanoparticle formulations.Chemotherapy with the use of cytotoxic drugs is commonly implemented in the management of many cancer types, e.g., breast cancers (Skeel, 2003;Tack et al., 2004). However, suboptimal therapeutic responses associated with multidrug resistance (MDR) frequently occur (Longley and Johnston, 2005). Overexpression of P-glycoprotein (Pgp) is one of the prominent mechanisms that contribute to the MDR phenotype (Endicott and Ling, 1989;Gottesman, 2002). Pgp is a 170-kDa membrane-associated glycoprotein that may actively extrude several substrates, including a variety of cytotoxic drugs such as doxorubicin (Dox), from cell cytoplasm to outside of plasma membrane, thus lowering the effective drug concentrations within the cells (Endicott and Ling, 1989;Gottesman, 2002). Because cytotoxic drugs typically carry numerous dose-limiting normal tissue side effects (Tipton, 2003), it is generally impractical to overcome this form of drug resistance simply by increasing the drug dose. To improve the therapeutic ratio of cancer chemotherapy, it is critical to establish alternative approaches that may improve accumulation and prolong retention of cytotoxic drugs in drug-resistant cancer cells without causing additional normal tissue side effects.Particulate drug delivery systems such as polymeric microspheres (...

Preparation, characterization, in vivo and in vitro studies of arsenic trioxide Mg-Fe ferrite magnetic nanoparticles

“…It is generally assumed that drugs on nanoparticles are released by several processes, such as diffusion through the polymer matrix, release by polymer degradation and solubilization and diffusion through microchannels that exist in the polymer matrix or are formed by erosion [21] . Because of the long biodegradation time of PLGA, we assume that the drug would be released from the nanoparticles through the diffusion mechanism in vitro.…”

Polymeric micelles based on poly(ethylene glycol) block poly(racemic amino acids) hybrid polypeptides: conformation-facilitated drug-loading behavior and potential application as effective anticancer drug carriers

“…This result suggests that the DTX-loaded micelles are more cytotoxic than the free drug against cancer cells, which is probably because the additional drug internalized in the cells resulted from endocytosis and enhanced intracellular drug accumulation by the nanoparticle uptake reported elsewhere. 33,34 The MCF-7 cell viability after incubation with the free DTX and DTX-loaded micelles at the same concentration (10 µM calculated by DTX) after 24 hours, 48 hours, 72 hours, and 96 hours is shown in Figure 13. With prolongation of the incubation time, a gradual decrease in cell viability was observed in the DTX-loaded micelles.…”

Reversal in multidrug resistance by magnetic nanoparticle of Fe3O4 loaded with adriamycin and tetrandrine in K562/A02 leukemic cells

“…Nanoparticles loaded with anticancer drug could readily approach the cell membrane, leading to drug concentrations at the cell surface higher than those obtained with the same amount of drug diluted in the culture medium, leading in turn to higher intracellular drug concentration (Hu et al 1996;Soma et al 2000). Not only have Fe 3 O 4 -MNPs the ability to block P-gp function, but also have the potent in aggregation and drugcapsulation (Wong et al 2006a(Wong et al , 2006b). This may be the reason that Fe 3 O 4 -MNPs which have no cytotoxicity to cells and no reversal in multidrug resistance are able to enhance ADM or Tet effective concentration intracellularly (Colin de Verdière et al 1994).…”