A mechanistic study of enhanced doxorubicin uptake and retention in multidrug resistant breast cancer cells using a polymer-lipid hybrid nanoparticle system

Deficiency in Cardiolipin Reduces Doxorubicin-Induced Oxidative Stress and Mitochondrial Damage in Human B-Lymphocytes

Cardiolipin (CL) is an inner mitochondrial membrane phospholipid which plays an important role in mitochondrial function. Perturbation in CL biosynthesis alters mitochondrial bioenergetics causing a severe genetic disorder commonly known as Barth syndrome. Barth syndrome patients are known to have a reduced concentration and altered composition of CL. Cardiolipin is also known to have a high affinity for the chemotherapeutic agent doxorubicin (Dox), resulting in an extensive mitochondrial accumulation of the drug. Our results indicate that B-lymphocytes from healthy individuals are more sensitive to Dox-induced oxidative stress and cellular toxicity compared to the B-lymphocytes from Barth syndrome as indicated by greater cell death and greater level of cleaved caspase-3 following Dox treatment. Barth lymphocytes, when compared to healthy lymphocytes, showed a greater basal level of mitochondrial reactive oxygen species (mito-ROS), yet exhibited a lower level of induced mito-ROS production in response to Dox. Significantly less ATP content and slightly greater OXPHOS protein levels were detected in healthy cells compared to Barth cells after Dox treatment. Consistent with greater mitochondrial ROS, treatment with Dox induced a higher level of lipid peroxidation and protein carbonylation in healthy lymphocytes compared to Barth lymphocytes. The final remodeling of CL during CL synthesis is catalyzed by the tafazzin protein. Knockdown of tafazzin gene in H9c2 cardiomyocytes using siRNA showed decreased oxidant-induced damage, as observed in Barth lymphocytes. Our findings demonstrate that a deficiency in CL might provide a therapeutic advantage in favor of oxidant-induced anticancer activities.

Lipid-Based Drug Delivery Systems in Cancer Therapy: What Is Available and What Is Yet to Come

Cancer is a leading cause of death in many countries around the world. However, the efficacy of current standard treatments for a variety of cancers is suboptimal. First, most cancer treatments lack specificity, meaning that these treatments affect both cancer cells and their normal counterparts. Second, many anticancer agents are highly toxic, and thus, limit their use in treatment. Third, a number of cytotoxic chemotherapeutics are highly hydrophobic, which limits their utility in cancer therapy. Finally, many chemotherapeutic agents exhibit short half-lives that curtail their efficacy. As a result of these deficiencies, many current treatments lead to side effects, noncompliance, and patient inconvenience due to difficulties in administration. However, the application of nanotechnology has led to the development of effective nanosized drug delivery systems known commonly as nanoparticles. Among these delivery systems, lipid-based nanoparticles, particularly liposomes, have shown to be quite effective at exhibiting the ability to: 1) improve the selectivity of cancer chemotherapeutic agents; 2) lower the cytotoxicity of anticancer drugs to normal tissues, and thus, reduce their toxic side effects; 3) increase the solubility of hydrophobic drugs; and 4) offer a prolonged and controlled release of agents. This review will discuss the current state of lipid-based nanoparticle research, including the development of liposomes for cancer therapy, different strategies for tumor targeting, liposomal formulation of various anticancer drugs that are commercially available, recent progress in liposome technology for the treatment of cancer, and the next generation of lipid-based nanoparticles.

Dermal delivery of doxorubicin-loaded solid lipid nanoparticles for the treatment of skin cancer

OBJECTIVE

Dermal delivery of Doxorubicin (Dox) would be an ideal way in maximising drug efficiency against skin cancer accompanying with minimising side effects. We investigated the potential of Dox-loaded Solid lipid nanoparticles (SLNs) for topical delivery against skin cancer.

METHODS

In vitro and in vivo cytotoxicity of optimised formulation were evaluated on murine melanoma (B16F10) cells by MTT assay and melanoma induced Balb/C mice, respectively. Animal study followed by histological analysis.

RESULTS

Optimised formulation showed mean particle size and encapsulation efficiency (EE) of 92 nm and 86% w/w (0.86% w/w value of encapsulated Dox in the lipid matrix), respectively. FTIR experiment confirmed drug-lipid interaction interpreting the observed high EE value for Dox. In vitro and in vivo results indicated the superiority of cytotoxic performance of Dox-loaded SLN compared to Dox solution.

CONCLUSION

Our findings may open the possibilities for the topical delivery of Dox to the skin cancerous tissues.

Poly (l-γ-glutamylglutamine) Polymer Enhances Doxorubicin Accumulation in Multidrug Resistant Breast Cancer Cells

Background: Drug resistance is one of the bottlenecks of cancer chemotherapy in the clinic. Polymeric nanomedicine is one of the most promising strategies for overcoming poor chemotherapy responses due to the multidrug resistance (MDR). Methods: In this study, a new polymer-based drug delivery system, poly (l-γ-glutamylglutamine)-doxorubicin (PGG-Dox) conjugate, was studied in both drug-induced resistant human breast cancer MDA-MB-231/MDR cells and their parent human breast cancer MDA-MB-231 cells. The effect of PGG on facilitating the growth inhibition of Dox against multidrug resistant cells were investigated by evaluating the cytotoxicity of PGG-Dox conjugate, PGG/Dox unconjugated complex and free Dox on both cells. The underlying mechanisms in resistant cells were further studied via the intracellular traffic studies. Results: Both conjugated and unconjugated PGG significantly increased Dox uptake, prolonged Dox retention and reduced Dox efflux in the MDA-MB-231/MDR cells. The PGG-Dox conjugate is taken up by tumor cells mainly by pinocytosis pathway, in which PGG-Dox conjugate-containing vesicles are formed and enter the cells. Conclusions: This study indicated that both polymer-drug conjugate and unconjugated complex are promising strategies of overcoming resistance of anti-tumor drugs.

Chitosan/Sterculia striata polysaccharides nanocomplex as a potential chloroquine drug release device

Nanoparticles are produced by means of polyelectrolyte complexation (PEC) of oppositely charged polycationic chitosan (CH) with polyanionic polysaccharide extracted from Sterculia striata exudates (rhamnogalacturonoglycan (RG)-type polysaccharide). The nanoparticles formed with low-molar-mass CH are larger than those formed with high-molar-mass CH. This behavior is in contrast with that previously observed for other systems and may be attributed to different mechanisms related to the association of CH with RG of higher persistence length chain than that of CH. Nanoparticles harnessed with a charge ratio (n(+)/n(-)) of <1 are smaller than particles with an excess of polycations. Particles with hydrodynamic sizes smaller than 100nm are achieved using a polyelectrolyte concentration of 10(-4)gmL(-1) and charge ratio (n(+)/n(-)) of <1. The CH/RG nanoparticles are associated with chloroquine (CQ) with an efficiency of 28% and release it for up to ∼60% within ∼10h, whereas in the latter, only ∼40% of the CQ was released after 24h. The main factor that influenced drug release rate is the nanoparticle charge ratio.

Overcoming doxorubicin resistance of cancer cells by Cas9-mediated gene disruption

In this study, Cas9 system was employed to down-regulate mdr1 gene for overcoming multidrug resistance of cancer cells. Disruption of the MDR1 gene was achieved by delivery of the Cas9-sgRNA plasmid or the Cas9-sgRNA ribonucleoprotein complex using a conventional gene transfection agent and protein transduction domain (PTD). Doxorubicin showed considerable cytotoxicity to the drug-resistant breast cancer cells pre-treated with the RNA-guided endonuclease (RGEN) systems, whereas virtually non-toxic to the untreated cells. The potency of drug was enhanced in the cells treated with the protein-RNA complex as well as in those treated with plasmids, suggesting that mutation of the mdr1 gene by intracellular delivery of Cas9-sgRNA complex using proper protein delivery platforms could recover the drug susceptibility. Therefore, Cas9-mediated disruption of the drug resistance-related gene can be considered as a promising way to overcome multidrug resistance in cancer cells.

Phytochemicals and Biogenic Metallic Nanoparticles as Anticancer Agents

Cancer is a leading cause of death worldwide. Several classes of drugs are available to treat different types of cancer. Currently, researchers are paying significant attention to the development of drugs at the nanoscale level to increase their target specificity and to reduce their concentrations. Nanotechnology is a promising and growing field with multiple subdisciplines, such as nanostructures, nanomaterials, and nanoparticles. These materials have gained prominence in science due to their size, shape, and potential efficacy. Nanomedicine is an important field involving the use of various types of nanoparticles to treat cancer and cancerous cells. Synthesis of nanoparticles targeting biological pathways has become tremendously prominent due to the higher efficacy and fewer side effects of nanodrugs compared to other commercial cancer drugs. In this review, different medicinal plants and their active compounds, as well as green-synthesized metallic nanoparticles from medicinal plants, are discussed in relation to their anticancer activities.

Nanostructured lipid-carrageenan hybrid carriers (NLCCs) for controlled delivery of mitoxantrone hydrochloride to enhance anticancer activity bypassing the BCRP-mediated efflux

Novel nanostructured lipid-carrageenan hybrid carriers (NLCCs) were exploited for controlled delivery of water soluble chemotherapeutic agent mitoxantrone hydrochloride (MTO) with high loading capacity, sustained release property, and potential for improving oral bioavailability and antitumor efficacy. By introducing the negative polymer of carrageenan, MTO was highly incorporated into NLCCs with encapsulation efficiency of 95.8% by electrostatic interaction. In vivo pharmacokinetics of MTO solution (MTO-Sol) and MTO-NLCCs in rats demonstrated that the apparent bioavailability of MTO-NLCCs was increased to approximate 3.5-fold compared to that of MTO-Sol. The cytotoxicity investigations by MTT method indicated that NLCCs could significantly enhanced the antitumor efficacy against resistant MCF-7/MX cells. The relative cellular association of MTO-NLCCs was 9.2-fold higher than that of MTO-Sol in breast cancer resistance protein (BCRP) over-expressing MCF-7/MX cells, implying that BCRP-mediated drug efflux was diminished by the introduction of NLCCs. The endocytosis inhibition study implied that the NLCCs entered the MCF-7/MX cells by clathrin-mediated endocytosis process, which can bypass the efflux of MTO mediated by BCRP. The new developed NLCCs provide an effective strategy for oral delivery of water-soluble MTO with improved encapsulation efficiency, oral bioavailability, and cytotoxicity against resistant breast cancer cells.

Biophysical and chemical handles to control the size of DNA nanoparticles produced by rolling circle amplification

The size of DNA nanoparticles produced by rolling circle amplification (RCA) can be controlled by incorporation of structure-forming sequences and amine-modified nucleotides in the replication part.

How can nanomedicines overcome cellular-based anticancer drug resistance?

This review discusses the mechanisms of anticancer drug resistance according to its cellular level of action and outlines the nanomedicine-based strategies adopted to overcome it.

Design of folic acid conjugated chitosan nano-cur–bioenhancers to attenuate the hormone-refractory metastatic prostate carcinoma by augmenting oral bioavailability

Folic acid conjugated nano-cur–bioenhancer as a functional P-glycoprotein inhibitor enhancing oral bioavailability of curcumin.

Phenytoin carried by silica core iron oxide nanoparticles reduces the expression of pharmacoresistant seizures in rats

Aim: The present study was focused to evaluate the anticonvulsant effects of phenytoin (PHT) loaded in the silica core of iron oxide nanoparticles (NPs) in an animal model with pharmacoresistant seizures. Materials & methods: PHT-loaded NPs were synthesized and characterized. The anticonvulsant effects of PHT-loaded NPs were investigated in rats with pharmacoresistant seizures associated with brain P-glycoprotein (P-gp) overexpression. Results & conclusion: In P-gp-overexpressing rats, administration of PHT-loaded NPs resulted in reduced prevalence of clonus (40% p < 0.05) and tonic–clonic seizures (20%; p < 0.02). These effects were not evident when animals were treated with PHT not loaded in the NPs. The results obtained support the notion that NPs can be used as drugs carriers to the brain with pharmacoresistant seizures.

Development of docetaxel nanocapsules for improving in vitro cytotoxicity and cellular uptake in MCF-7 cells

The aim of this study was to fabricate docetaxel loaded nanocapsules (DTX-NCs) with a high payload using Layer-by-Layer (LbL) technique by successive coating with alternate layers of oppositely charged polyelectrolytes. Developed nanocapsules (NCs) were characterized in terms of morphology, particle size distribution, zeta potential (ζ-potential), entrapment efficiency and in vitro release. The morphological characteristics of the NCs were assessed using transmission electron microscopy (TEM) that revealed coating of polyelectrolytes around the surface of particles. The developed NCs successfully attained a submicron particle size while the ζ-potential of optimized NCs alternated between (+) 34.64 ± 1.5 mV to (-) 33.25 ± 2.1 mV with each coating step. The non-hemolytic potential of the NCs indicated the suitability of the developed formulation for intravenous administration. A comparative study indicated that the cytotoxicity of positively charged NCs (F4) was significant higher (p < 0.05) rather than negative charged NCs (F3), plain drug (DTX) and marketed preparation (Taxotere®) when evaluated in vitro on MCF-7 cells. Furthermore, cell uptake studies evidenced a higher uptake of positive NCs (≥1.2 fold) in comparison to negative NCs. In conclusion, formulated NCs are an ideal vehicle for passive targeting of drugs to tumor cells that may result in improved efficacy and reduced toxicity of encapsulated drug moiety.

Methotrexate-conjugated quantum dots: synthesis, characterisation and cytotoxicity in drug resistant cancer cells

Methotrexate (MTX), a folic acid derivative, is a potent anticancer used for treatment of different malignancies, but possible initiation of drug resistance to MTX by cancer cells has limited its applications. Nanoconjugates (NCs) of MTX to quantum dots (QDs) may favour the cellular uptake via folate receptors (FRs)-mediated endocytosis that circumvents the efflux functions of cancer cells. We synthesised MTX-conjugated l-cysteine capped CdSe QDs (MTX-QD nanoconjugates) and evaluated their internalisation and cytotoxicity in the KB cells with/without resistancy to MTX. The NCs were fully characterised by high resolution transmission electron microscopy (HR-TEM), atomic force microscopy (AFM), dynamic light scattering (DLS) and optical spectroscopy. Upon conjugation with MTX, the photoluminescence (PL) properties of QDs altered, while an obvious quenching in PL of QDs was observed after physical mixing. The MTX-QD nanoconjugates efficiently internalised into the cancer cells, and induced markedly high cytotoxicity (IC50, 12.0 µg/mL) in the MTX-resistant KB cells as compared to the free MTX molecules (IC50,105.0 µg/mL), whereas, these values were respectively about 7.0 and 0.6 µg/mL in the MTX-sensitive KB cells. Based on these findings, the MTX-QD nanoconjugates are proposed for the targeted therapy of MTX-resistant cancers, which may provide an improved outcome in the relapsed FR-overexpressing cancers.

[Composites of peptide nucleic acids with titanium dioxide nanoparticles. III. Kinetics of PNA dissociation from nanocomposites containing DNA/PNA duplexes]

When delivering peptide nucleic acids (PNA) to the cells in the nanocomposites TiO2 · PL · DNA/PNA, containing titanium dioxide nanoparticles coated with polylysine (PL) and immobilized DNA/PNA duplexes, it is important not only to transport them to the cell, but also ability to control the release rate of the PNA-drug from the carrier. PNA desorption from TiO2 · PL · DNA/PNA nanocomposite in time has been shown. Desorption is caused by dissociation of immobilized DNA/PNA duplex while the DNA remains on the carrier and PNA goes away in solution. It has been found that the half-retention times of PNA on TiO2 · PL · DNA/PNA nanocomposites containing DNA/PNA duplexes with overlapping complementary base pairs equal to 10, 12, 14, and 16 are 10, 14, 22 and 70 minutes, respectively. Thus, it has been shown that the release rate of the PNA-drug from nanocomposites can be adjusted by varying the overlap of complementary base pairs in the immobilized DNA/PNA duplex. This method of PNA immobilization may be used for designing of nanocomposites with optimum release time of the PNA-drugs. Created TiO2 · PL · DNA/PNA nanocomposites can be used to efficiently deliver therapeutically significant drug PNA and their selective effect on the pathogenic nucleic acid in the cell.

The self-assembling camptothecin-tocopherol prodrug: An effective approach for formulating camptothecin

Camptothecin (CPT) is a potent antitumor agent and functions via inhibiting the activity of topoisomerase I during DNA replication. However, the clinical application of CPT has been greatly hindered by its extremely poor solubility, the instability of its active lactone ring in blood stream, as well as the non-specific toxicity to normal tissues. In addition, most of the formulations developed so far are not applicable for formulating CPT. In this study, two novel CPT prodrugs were developed by conjugating CPT to α-tocopherol via a carbonate ester bond (CPT-VE) or disulfide linkage (CPT-S-S-VE). Both CPT prodrugs were able to self-assemble into nanofibers with the facilitation of a PEG5K-Fmoc-VE2-based nanomicellar carrier. Both prodrug nanoassemblies exhibited excellent stability. Fluorescence quenching, UV absorbance, and FT-IR studies demonstrated strong interactions between carrier and prodrugs, including hydrophobic interaction, π-π stacking, as well as hydrogen bonding. NMR studies suggested that prodrugs were successfully incorporated into PEG5K-Fmoc-VE2 during self-assembly process. In vitro, PEG5K-Fmoc-VE2/CPT-S-S-VE presented significantly higher level of cytotoxicity on tumor cells compared to PEG5K-Fmoc-VE2/CPT-VE. Biodistribution study showed that CPT-S-S-VE formulated in PEG5K-Fmoc-VE2 micelles was effectively converted to parent CPT following delivery to tumor tissues. Finally, PEG5K-Fmoc-VE2/CPT-S-S-VE nanofibers showed superior tumor growth inhibition in an aggressive murine breast cancer model (4T1.2).

Aspartate-modified doxorubicin on its N-terminal increases drug accumulation in LAT1-overexpressing tumors

L-type amino acid transporter 1 (LAT1), overexpressed on the membrane of various tumor cells, is a potential target for tumor-targeting therapy. This study aimed to develop a LAT1-mediated chemotherapeutic agent. We screened doxorubicin modified by seven different large neutral amino acids. The aspartate-modified doxorubicin (Asp-DOX) showed the highest affinity (Km = 41.423 μmol/L) to LAT1. Aspartate was attached to the N-terminal of DOX by the amide bond with a free carboxyl and a free amino group on the α-carbon atom of the Asp residue. The product Asp-DOX was characterized by HPLC/MS. In vitro, Asp-DOX exerted stronger inhibition on the cancer cells overexpressing LAT1 and the uptake of Asp-DOX was approximately 3.5-fold higher than that of DOX in HepG2 cells. Pharmacokinetic data also showed that Asp-DOX was expressed over a longer circulation time (t1/2 = 49.14 min) in the blood compared to DOX alone (t1/2 = 15.12 min). In HepG2 and HCT116 tumor-bearing mice, Asp-DOX achieved 3.1-fold and 6.4-fold accumulation of drugs in tumor tissue, respectively, than those of the unmodified DOX. More importantly, treatment of tumor-bearing mice with Asp-DOX showed a significantly stronger inhibition of tumor growth than mice treated with free DOX in HepG2 tumor models. Furthermore, after Asp modification, Asp-DOX avoided MDR mediated by P-glycoprotein. These results suggested that the Asp-DOX modified drug may provide a new treatment strategy for tumors that overexpress LAT1 and MDR1.

Doxorubicin loaded magnetic gold nanoparticles for in vivo targeted drug delivery

Treatment of approximately 50% of human cancers includes the use of chemotherapy. The major problem associated with chemotherapy is the inability to deliver pharmaceuticals to specific site of the body without inducing normal tissue toxicity. Latterly, magnetic targeted drug delivery (MTD) has been used to improve the therapeutic performance of the chemotherapeutic agents and reduce the severe side effects associated with the conventional chemotherapy for malignant tumors. In this study, we were focused on designing biocompatible magnetic nanoparticles that can be used as a nanocarrier's candidate for MTD regimen. Magnetic gold nanoparticles (MGNPs) were prepared and functionalized with thiol-terminated polyethylene glycol (PEG), then loaded with anti-cancer drug doxorubicin (DOX). The physical properties of the prepared NPs were characterized using different techniques. Transmission electron microscopy (TEM) revealed the spherical mono-dispersed nature of the prepared MGNPs with size about 22 nm. Energy dispersive X-ray spectroscopy (EDX) assured the existence of both iron and gold elements in the prepared nanoparticles. Fourier transform infrared (FTIR) spectroscopy assessment revealed that PEG and DOX molecules were successfully loaded on the MGNPs surfaces, and the amine group of DOX is the active attachment site to MGNPs. In vivo studies proved that magnetic targeted drug delivery can provide a higher accumulation of drug throughout tumor compared with that delivered by passive targeting. This clearly appeared in tumor growth inhibition assessment, biodistribution of DOX in different body organs in addition to the histopathological examinations of treated and untreated Ehrlich carcinoma. To assess the in vivo toxic effect of the prepared formulations, several biochemical parameters such as aspartate aminotransferase (AST), alanine transaminase (ALT), lactate dehydrogenase (LDH), creatine kinase MB (CK-MB), urea, uric acid and creatinine were measured. MTD technology not only minimizes the random distribution of the chemotherapeutic agents, but also reduces their side effects to healthy tissues, which are the two primary concerns in conventional cancer therapies.

Nanotechnology-Based Drug Delivery Systems for Melanoma Antitumoral Therapy: A Review

Melanoma (MEL) is a less common type of skin cancer, but it is more aggressive with a high mortality rate. The World Cancer Research Fund International (GLOBOCAN 2012) estimates that there were 230,000 new cases of MEL in the world in 2012. Conventional MEL treatment includes surgery and chemotherapy, but many of the chemotherapeutic agents used present undesirable properties. Drug delivery systems are an alternative strategy by which to carry antineoplastic agents. Encapsulated drugs are advantageous due to such properties as high stability, better bioavailability, controlled drug release, a long blood circulation time, selective organ or tissue distribution, a lower total required dose, and minimal toxic side effects. This review of scientific research supports applying a nanotechnology-based drug delivery system for MEL therapy.

Facile Synthesis of PEGylated PLGA Nanoparticles Encapsulating Doxorubicin and its In Vitro Evaluation as Potent Drug Delivery Vehicle

The advent of nanotechnology has bolstered a variety of nanoparticles based platforms for different biomedical applications. A better understanding for engineering novel nanoparticles for applications in cancer staging and therapy requires careful assessment of the nanoparticle's physico-chemical properties. Herein we report a facile synthesis method for PEGylated PLGA nanoparticles encapsulating anti-cancer drug doxorubicin for cancer imaging and therapy. The simple nanoprecipitation method reported here resulted in very robust PEGylated PLGA nanoparticles with close to 95% drug encapsulation efficiency. The nanoparticles showed a size of ~110 nm as characterized by TEM and DLS. The nanoparticles were further characterized by optical UV-Visible and fluorescence spectroscopy. The encapsulated doxorubicin showed a sustained release (>80%) from the nanoparticles matrix over a period of 8 days. The drug delivery efficiency of the nanoparticles was confirmed in vitro confocal imaging with PC3 and HeLa cell lines. In vitro quantitative estimation of drug accumulation in PC3 cell line showed a 22 times higher concentration of drug in case of nanoparticles based formulation in comparison to free drug and this was further reflected in the in vitro cytotoxicity assays. Overall the synthesis method reported here provides a simple and robust PLGA based platform for efficient drug delivery and imaging of cancer cells in vitro and in vivo.

Active Drug Targeting of a Folate-Based Cyclodextrin-Doxorubicin Conjugate and the Cytotoxic Effect on Drug-Resistant Mammary Tumor Cells In Vitro

Active drug targeting is an effective therapeutic approach for the treatment of malignant cancers and novel types of drug carriers have been developed. In this study, we developed a cyclodextrin (CD)-based novel carrier-drug conjugate, called per-FOL-β-CD-ss-DOX, which has folic acid (FA) molecules at the end of primary hydroxyl groups of β-CD and a pH-cleavable spacer with an anticancer drug, doxorubicin (DOX), at the end of secondary hydroxyl groups. This per-FOL-β-CD-ss-DOX exhibited a significant cellular uptake as compared with the free DOX solution by EMT6/P cells, which activate the expression of folate receptor (FR). Cellular uptake of per-FOL-β-CD-ss-DOX was significantly inhibited in the presence of FA and was also inhibited at 4°C. The conjugate exhibited remarkable cytotoxic effects in EMT6/AR1 cells, which are resistant to DOX, whereas free DOX solution did not exhibit this effect. These results suggest that per-FOL-β-CD-ss-DOX can be taken up into cells via FR-related endocytosis and the cleaved DOX derived from it in endosomes could escape the efflux caused by P-glycoprotein, resulting in the cytotoxic effect. Therefore, the drug delivery by per-FOL-β-CD-ss-DOX may be a useful approach for drug delivery to FR-expressing cells such as drug-resistant malignant cancers.

Micelle Delivery of Parthenolide to Acute Myeloid Leukemia Cells

Parthenolide (PTL) has shown great promise as a novel anti-leukemia agent as it selectively eliminates acute myeloid leukemia (AML) blast cells and leukemia stem cells (LSCs) while sparing normal hematopoietic cells. This success has not yet translated to the clinical setting because PTL is rapidly cleared from blood due to its hydrophobicity. To increase the aqueous solubility of PTL, we previously developed micelles formed from predominantly hydrophobic amphiphilic diblock copolymers of poly(styrene-alt-maleic anhydride)-b-poly(styrene) (e.g., PSMA₁₀₀-b-PS₂₅₈) that exhibit robust PTL loading (75%efficiency, 11% w/w capacity) and release PTL over 24 h. Here, PTL-loaded PSMA-b-PS micelles were thoroughly characterized in vitro for PTL delivery to MV4-11 AML cells. Additionally, the mechanisms governing micelle-mediated cytotoxicity were examined in comparison to free PTL. PSMA-b-PS micelles were taken up by MV4-11 cells as evidenced by transmission electron microscopy and flow cytometry. Specifically, MV4-11 cells relied on clathrin-mediated endocytosis, rather than caveolae-mediated endocytosis and macropinocytosis. In addition, PTL-loaded PSMA-b-PS micelles exhibited a dose-dependent cytotoxicity towards AML cells and were capable of reducing cell viability by 75% at 10 μM PTL, while unloaded micelles were nontoxic. At 10 μM PTL, the cytotoxicity of PTL-loaded micelles increased gradually over 24 h while free PTL achieved maximal cytotoxicity between 2 and 4 h, demonstrating micelle-mediated delivery of PTL to AML cells and stability of the drug-loaded micelle even in the presence of cells. Both free PTL and PTL-loaded micelles induced NF-κB inhibition at 10 μM PTL doses, demonstrating some mechanistic similarities in cytotoxicity. However, free PTL relied more heavily on exofacial free thiol interactions to induce cytotoxicity than PTL-loaded micelles; free PTL cytotoxicity was reduced by over twofold when cell surface free thiols were depleted, where PTL-loaded micelle doses were unaffected by cell surface thiol modulation. The physical properties, stability, and efficacy of PTL-loaded PSMA-b-PS micelles support further development of a leukemia therapeutic with greater bioavailability and the potential to eliminate LSCs.

Folate-modified lipid-polymer hybrid nanoparticles for targeted paclitaxel delivery

The purpose of this study was to develop a novel lipid-polymer hybrid drug carrier comprised of folate (FA) modified lipid-shell and polymer-core nanoparticles (FLPNPs) for sustained, controlled, and targeted delivery of paclitaxel (PTX). The core-shell NPs consist of 1) a poly(ε-caprolactone) hydrophobic core based on self-assembly of poly(ε-caprolactone)-poly(ethylene glycol)-poly(ε-caprolactone) (PCL-PEG-PCL) amphiphilic copolymers, 2) a lipid monolayer formed with 1,2-distearoyl-sn-glycero-3-phosphoethanolamine-N-[methoxy (polyethylene glycol)-2000] (DSPE-PEG2000), 3) a targeting ligand (FA) on the surface, and were prepared using a thin-film hydration and ultrasonic dispersion method. Transmission electron microscopy and dynamic light scattering analysis confirmed the coating of the lipid monolayer on the hydrophobic polymer core. Physicochemical characterizations of PTX-loaded FLPNPs, such as particle size and size distribution, zeta potential, morphology, drug loading content, encapsulation efficiency, and in vitro drug release, were also evaluated. Fluorescent microscopy proved the internalization efficiency and targeting ability of the folate conjugated on the lipid monolayer for the EMT6 cancer cells which overexpress folate receptor. In vitro cytotoxicity assay demonstrated that the cytotoxic effect of PTX-loaded FLPNPs was lower than that of Taxol(®), but higher than that of PTX-loaded LPNPs (without folate conjugation). In EMT6 breast tumor model, intratumoral administration of PTX-loaded FLPNPs showed similar antitumor efficacy but low toxicity compared to Taxol(®). More importantly, PTX-loaded FLPNPs showed greater tumor growth inhibition (65.78%) than the nontargeted PTX-loaded LPNPs (48.38%) (P<0.05). These findings indicated that the PTX loaded-FLPNPs with mixed lipid monolayer shell and biodegradable polymer core would be a promising nanosized drug formulation for tumor-targeted therapy.

Polymeric nanoparticles for targeted treatment in oncology: current insights

Chemotherapy, a major strategy for cancer treatment, lacks the specificity to localize the cancer therapeutics in the tumor site, thereby affecting normal healthy tissues and advocating toxic adverse effects. Nanotechnological intervention has greatly revolutionized the therapy of cancer by surmounting the current limitations in conventional chemotherapy, which include undesirable biodistribution, cancer cell drug resistance, and severe systemic side effects. Nanoparticles (NPs) achieve preferential accumulation in the tumor site by virtue of their passive and ligand-based targeting mechanisms. Polymer-based nanomedicine, an arena that entails the use of polymeric NPs, polymer micelles, dendrimers, polymersomes, polyplexes, polymer–lipid hybrid systems, and polymer–drug/protein conjugates for improvement in efficacy of cancer therapeutics, has been widely explored. The broad scope for chemically modifying the polymer into desired construct makes it a versatile delivery system. Several polymer-based therapeutic NPs have been approved for clinical use. This review provides an insight into the advances in polymer-based targeted nanocarriers with focus on therapeutic aspects in the field of oncology.

Formulation and optimization of itraconazole polymeric lipid hybrid nanoparticles (Lipomer) using Box Behnken design

Background

The objective of the study was to formulate and to investigate the combined influence of 3 independent variables in the optimization of Polymeric lipid hybrid nanoparticles (PLHNs) (Lipomer) containing hydrophobic antifungal drug Itraconazole and to improve intestinal permeability.

Method

The Polymeric lipid hybrid nanoparticle formulation was prepared by the emulsification solvent evaporation method and 3 factor 3 level Box Behnken statistical design was used to optimize and derive a second order polynomial equation and construct contour plots to predict responses. Biodegradable Polycaprolactone, soya lecithin and Poly vinyl alcohol were used to prepare PLHNs. The independent variables selected were lipid to polymer ratio (X₁) Concentration of surfactant (X₂) Concentration of the drug (X₃).

Result

The Box-Behnken design demonstrated the role of the derived equation and contour plots in predicting the values of dependent variables for the preparation and optimization of Itraconazole PLHNs. Itraconazole PLHNs revealed nano size (210 ± 1.8 nm) with an entrapment efficiency of 83 ± 0.6% and negative zeta potential of −11.7 mV and also enhance the permeability of itraconazole as the permeability coefficient (P_app) and the absorption enhancement ratio was higher.

Conclusion

The tunable particle size, surface charge, and favourable encapsulation efficiency with a sustained drug release profile of PLHNs suggesting that it could be promising system envisioned to increase the bioavailability by improving intestinal permeability through lymphatic uptake, M cell of payer’s patch or paracellular pathway which was proven by confocal microscopy.

Multifunctional hybrid nanoparticles based on sodium carboxymethylcellulose-graft-histidine and TPGS for enhanced effect of docetaxel

Multifunctional hybrid nanoparticles that comprised of sodium carboxymethylcellulose-graft-histidine (CMH) and TPGS were designed for overcoming MDR of docetaxel.

Coencapsulated doxorubicin and bromotetrandrine lipid nanoemulsions in reversing multidrug resistance in breast cancer in vitro and in vivo

Multidrug resistance has remained a major cause of treatment failure in chemotherapy due to the presence of P-glycoproteins (P-gp) that actively pump drugs from inside the cell to the outside. P-gp inhibitors were developed and coadministered with chemotherapeutic drugs to overcome the effect of efflux pumps thus enhancing the chemosensitivity of therapeutics. Our study aimed at developing a lipid nanoemulsion system for the coencapsulation of doxorubicin (DOX) and bromotetrandrine (W198) to reverse multidrug resistance (MDR) in breast cancer. W198 was a potent P-gp inhibitor, and DOX was selected as a model compound which is a common substrate for P-gp. Coencapsulated DOX and W198 lipid nanoemulsions (DOX/W198-LNs) displayed significantly enhanced cytotoxicity in DOX-resistant human breast cancer cells (MCF-7/ADR) compared with DOX loaded lipid nanoemulsions (DOX-LNs) (p < 0.05), which is due to the enhanced intracellular uptake of DOX in MCF-7/ADR cells. The biodistribution study was performed using a nude mice xenograft model, which demonstrates enhanced tumor uptake of DOX in the DOX/W198-LN treated group. Compared with DOX solution, DOX/W198-LNs showed reduced cardiac toxicity and gastrointestinal injury in rats. Taken together, DOX/W198-LNs represent a promising formulation for overcoming MDR in breast cancer.

Co-delivery of doxorubicin and P-gp inhibitor by a reduction-sensitive liposome to overcome multidrug resistance, enhance anti-tumor efficiency and reduce toxicity

To overcome multidrug resistance (MDR) in cancer chemotherapy with high efficiency and safety, a reduction-sensitive liposome (CL-R8-LP), which was co-modified with reduction-sensitive cleavable PEG and octaarginine (R8) to increase the tumor accumulation, cellular uptake and lysosome escape, was applied to co-encapsulate doxorubicin (DOX) and a P-glycoprotein (P-gp) inhibitor of verapamil (VER) in this study. The encapsulation efficiency (EE) of DOX and VER in the binary-drug loaded CL-R8-LP (DOX + VER) was about 95 and 70% (w/w), respectively. The uptake efficiencies, the cytotoxicity, and the apoptosis and necrosis-inducing efficiency of CL-R8-LP (DOX + VER) were much higher than those of DOX and the other control liposomes in MCF-7/ADR cells or tumor spheroids. Besides, CL-R8-LP (DOX + VER) was proven to be uptaken into MCF-7/ADR cells by clathrin-mediated and macropinocytosis-mediated endocytosis, followed by efficient lysosomal escape. In vivo, CL-R8-LP (DOX + VER) effectively inhibited the growth of MCF-7/ADR tumor and reduce the toxicity of DOX and VER, which could be ascribed to increased accumulation of drugs in drug-resistant tumor cells and reduced distribution in normal tissues. In summary, the co-delivery of chemotherapeutics and P-gp inhibitors by our reduction-sensitive liposome was a promising approach to overcome MDR, improve anti-tumor effect and reduce the toxicity of chemotherapy.

Cancer-targeted MDR-1 siRNA delivery using self-cross-linked glycol chitosan nanoparticles to overcome drug resistance

P-glycoprotein (Pgp) mediated multi-drug resistance (MDR) is a major cause of failure in chemotherapy. In this study, small interfering RNA (siRNA) for Pgp down-regulation was delivered to tumors to overcome MDR in cancer. To achieve an efficient siRNA delivery in vivo, self-polymerized 5'-end thiol-modified siRNA (poly-siRNA) was incorporated in tumor targeting glycol chitosan nanoparticles. Pgp-targeted poly-siRNA (psi-Pgp) and thiolated glycol chitosan polymers (tGC) formed stable nanoparticles (psi-Pgp-tGC NPs), and the resulting nanoparticles protected siRNA molecules from enzymatic degradation. The psi-Pgp-tGC NPs could release functional siRNA molecules after cellular delivery, and they were able to facilitate siRNA delivery to Adriamycin-resistant breast cancer cells (MCF-7/ADR). After intravenous administration, the psi-Pgp-tGC NPs accumulated in MCF-7/ADR tumors and down-regulated P-gp expression to sensitize cancer cells. Consequently, chemo-siRNA combination therapy significantly inhibited tumor growth without systemic toxicity. These psi-Pgp-tGC NPs showed great potential as a supplementary therapeutic agent for drug-resistant cancer.

Resveratrol modulates the topoisomerase inhibitory potential of doxorubicin in human colon carcinoma cells

Resveratrol (RSV) is currently being widely discussed as potentially useful for anticancer therapy in combination with classical chemotherapeutics, e.g., the topoisomerase II (TOP II) poison doxorubicin (DOX). However, there is still a lack of knowledge of possible interference at the target enzyme, especially since RSV itself has recently been described to act as a TOP poison. We therefore sought to address the question whether RSV affects DOX-induced genotoxic and cytotoxic effects with special emphasis on TOP II in HT-29 colon carcinoma cells. RSV was found to counteract DOX-induced formation of DNA-TOP-intermediates at ≥100 µM for TOP IIα and at 250 µM for TOP IIβ. As a consequence, RSV modulated the DNA-strand breaking potential of DOX by mediating protective effects with an apparent maximum at 100 µM. At higher concentration ranges (≥200 µM) RSV diminished the intracellular concentrations of DOX. Nevertheless, the presence of RSV slightly enhanced the cytotoxic effects of DOX after 1.5 h and 24 h of incubation. Taken together, at least in cell culture RSV was found to affect the TOP-poisoning potential of DOX and to modulate its cytotoxic effectiveness. Thus, further studies are needed to clarify the impact of RSV on the therapeutic effectiveness of DOX under in vivo conditions.

Mechanisms of nanoparticle internalization and transport across an intestinal epithelial cell model: effect of size and surface charge

This study investigated the effect of nanoparticle size (50 and 100 nm) and surface charge on their interaction with Caco-2 monolayers as a model of the intestinal epithelium, including cell internalization pathways and the level of transepithelial transport. Initially, toxicity assays showed that cell viability and cell membrane integrity were dependent on the surface charge and applied mass, number, and total surface area of nanoparticles, as tested in two epithelial cell lines, colon carcinoma Caco-2 and airway Calu-3. This also identified suitable nanoparticle concentrations for subsequent cell uptake experiments. Nanoparticle application at doses below half maximal effective concentration (EC₅₀) revealed that the transport efficiency (ratio of transport to cell uptake) across Caco-2 cell monolayers is significantly higher for negatively charged nanoparticles compared to their positively charged counterparts (of similar size), despite the higher level of internalization of positively charged systems. Cell internalization pathways were hence probed using a panel of pharmacological inhibitors aiming to establish whether the discrepancy in transport efficiency is due to different uptake and transport pathways. Vesicular trans-monolayer transport for both positively and negatively charged nanoparticles was confirmed via inhibition of dynamin (by dynasore) and microtubule network (via nocodazole), which significantly reduced the transport of both nanoparticle systems. For positively charged nanoparticles a significant decrease in internalization and transport (46% and 37%, respectively) occurred in the presence of a clathrin pathway inhibitor (chlorpromazine), macropinocytosis inhibition (42%; achieved by 5-(N-ethyl-N-isopropyi)-amiloride), and under cholesterol depletion (38%; via methyl-β-cyclodextrin), but remained unaffected by the inhibition of lipid raft associated uptake (caveolae) by genistein. On the contrary, the most prominent reduction in internalization and transport of negatively charged nanoparticles (51% and 48%, respectively) followed the inhibition of lipid raft-associated pathway (caveolae inhibition by genistein) but was not significantly affected by the inhibition of clathrin pathway.

Lipid polymer hybrid as emerging tool in nanocarriers for oral drug delivery

The oral route for drug delivery is a widely accepted route. For that reason, many researchers are currently working to develop efficient oral drug delivery systems. Use of polymeric nanoparticles (NPs) and lipid carrier systems, including liposomes, solid lipid nanoparticles (SLNs) and nanostructured lipid carriers (NLC), has limitations such as drug leakage and high water content of dispersions. Thus, lipid polymer hybrid nanoparticles (LPNs) have been explored by the researchers to provide a better effect using properties of both polymers and lipids. The present review is focused on the challenges, possibilities, and future perspectives of LPNs for oral delivery.

Hesperidin as a preventive resistance agent in MCF-7 breast cancer cells line resistance to doxorubicin

OBJECTIVE

To evaluate of hesperidin to overcome resistance of doxorubicin in MCF-7 resistant doxorubicin cells (MCF-7/Dox) in cytotoxicity apoptosis and P-glycoprotein (Pgp) expression in combination with doxorubicin.

METHODS

The cytotoxic properties, 50% inhibition concentration (IC50) and its combination with doxorubicin in MCF-7 cell lines resistant to doxorubicin (MCF-7/Dox) cells were determined using MTT assay. Apoptosis induction was examined by double staining assay using ethidium bromide-acridine orange. Immunocytochemistry assay was performed to determine the level and localization of Pgp.

RESULTS

Single treatment of hesperidin showed cytotoxic activity on MCF-7/Dox cells with IC50 value of 11 µmol/L. Thus, combination treatment from hesperidin and doxorubicin showed addictive and antagonist effect (CI>1.0). Hesperidin did not increase the apoptotic induction, but decreased the Pgp expressions level when combined with doxorubicin in low concentration.

CONCLUSIONS

Hesperidin has cytotoxic effect on MCF-7/Dox cells with IC50 of 11 µmol/L. Hesperidin did not increased the apoptotic induction combined with doxorubicin. Co-chemotherapy application of doxorubicin and hesperidin on MCF-7/Dox cells showed synergism effect through inhibition of Pgp expression.

Redox-responsive mesoporous silica nanoparticles: a physiologically sensitive codelivery vehicle for siRNA and doxorubicin

AIMS

Efficient siRNA/drug codelivery carriers can offer great promises to cancer treatment on account of synergistic effect provided from cancer-associated gene and anticancer drugs. In this work, a redox-responsive drug/siRNA codelivery vehicle based on mesoporous silica nanoparticles was fabricated to simultaneously deliver siRNA and doxorubicin (Dox) in vitro and in vivo.

RESULTS

The nanoparticle surface was functionalized with the adamantane (AD) units. Formation of stable host-guest complex between disulfide bond linked-AD and ethylenediamine-modified β-cyclodextrin is capable of fully blocking drugs inside the nanopores, while amino groups can complex with siRNA via electrostatic interaction. Relatively high concentration of glutathione in biophysical environment provides natural reducing agent to trigger drug/siRNA release by cleaving pre-introduced disulfide bonds. B-cell lymphoma 2 (Bcl-2) siRNA was codelivered to silence Bcl-2 protein expression in HeLa cells, resulting in enhanced chemotherapy efficacy in vitro. In vivo delivery experiment carried out in transgenic zebrafish larvae indicates that the delivery of Dox inhibits the development of choroid plexus in a dose-dependent manner, leading to successful decrease of green fluorescence protein transcription in choroid plexus. Reduction of liver tumor was also demonstrated after injection of Dox-loaded nanoparticles.

INNOVATION

We successfully demonstrated that functional nanoparticles could serve as an efficient carrier for the delivery of Bcl-2 siRNA and Dox in HeLa cells and in transgenic zebrafish larvae, leading to enhanced therapeutic efficacy.

CONCLUSION

Enhanced cytotoxicity caused by simultaneous delivery of Bcl-2 siRNA and Dox was observed in HeLa cells. Drug-loaded nanoparticles were internalized in vivo, inhibiting the development of choroid plexus and the progression of liver tumor.

Therapeutic potential of nanocarrier for overcoming to P-glycoprotein

Enhancement of targeted therapeutic effect in the body and achievement of high bioavailability are major concern for the researchers due to the complex physiology of human body. There are so many barriers that hinder the absorption and permeation of drugs from the body, thus influencing the bioavailability of therapeutics. P-glycoprotein (P-gp) is one of such barrier present on the apical membranes of various organs such as small intestine, brain, kidney and liver. This protein interacts with vast variety of therapeutics and efflux out them preventing their entrance to the desired site, thus modulating their pharmacokinetic properties. To address this, a concerned number of approaches have been used such as the use of chemo sensitizers along with the therapeutics and various novel techniques. In this review, we are going to discuss the basic introduction to this protein and overview of various strategies used earlier to tackle the problem of P-gp efflux as well as the role of nanocarriers in confronting this issue. Nanocarriers have played great role in the enhancement of the bioavailability of many antineoplastic agents as well as other P-gp substrates. Encapsulation of P-gp inhibitors in the nanocarrier system prevents toxicity and gives site-specific action.

Poly(styrene-alt-maleic anhydride)-based diblock copolymer micelles exhibit versatile hydrophobic drug loading, drug-dependent release, and internalization by multidrug resistant ovarian cancer cells

Amphiphilic diblock copolymers of poly(styrene-alt-maleic anhydride)-b-poly(styrene) (PSMA-b-PS) and poly(styrene-alt-maleic anhydride)-b-poly(butyl acrylate) (PSMA-b-PBA) were synthesized via reversible addition-fragmentation chain transfer (RAFT) polymerizations. Polymers were well-controlled with respect to molecular weight evolution and polydispersity indices (PDI < 1.2). Additionally, RAFT allowed for control of diblock compositions (i.e., ratio of hydrophilic PSMA blocks to hydrophobic PS/PBA blocks) and overall molecular weight, which resulted in reproducible self-assembly of diblocks into micelle nanoparticles with diameters of 20-100 nm. Parthenolide (PTL), a hydrophobic anticancer drug, was loaded and released from the micelles. The highest loading and prolonged release of PTL was observed from predominantly hydrophobic PSMA-b-PS micelles (e.g., PSMA100-b-PS258), which exhibited the most ordered hydrophobic environment for more favorable core-drug interactions. PSMA100-b-PS258 micelles were further loaded with doxorubicin (DOX), as well as two hydrophobic fluorescent probes, nile red and IR-780. While PTL released quantitatively within 24 h, DOX, IR-780, and nile red showed release over 1 week, suggesting stronger drug-core interactions and/or hindrance due to less favorable drug-solvent interactions. Finally, uptake and intracellular localization of PSMA100-b-PS258 micelles by multidrug resistant (MDR) ovarian cancer cells was observed by transmission electron microscopy (TEM). Additionally, in vitro analyses showed DOX-loaded PSMA-b-PS micelles exhibited greater cytotoxicity to NCI/ADR RES cells than equivalent free DOX doses (75% reduction in cell viability by DOX-loaded micelles compared to 40% reduction in viability by free DOX at 10 μM DOX), likely due to avoidance of MDR mechanisms that limit free hydrophobic drug accumulation. The ability of micelles to achieve intracellular delivery via avoidance of MDR mechanisms, along with the versatility of chemical constituents and drug loading and release rates, offer many advantages for a variety of drug delivery applications.

Synergistic nanoparticulate drug combination overcomes multidrug resistance, increases efficacy, and reduces cardiotoxicity in a nonimmunocompromised breast tumor model

Anthracyclines, commonly employed for cancer chemotherapy, suffer from dose-limiting cardiotoxicity and poor efficacy due to multidrug resistance (MDR). We previously demonstrated that simultaneous delivery of the synergistic drugs doxorubicin (DOX) and mitomycin C (MMC) by polymer-lipid hybrid nanoparticles (PLN) circumvented MDR, increased efficacy, and reduced cardiotoxicity in immuncompromised mice superior to poly(ethylene glycol)-coated (PEGylated) lipososmal DOX (PLD). Herein it is shown that the DOX-MMC combination was also synergistic in MDR EMT6/AR1 murine breast cancer cells and that their nanoparticle formulations were able to overcome the MDR phenotype. In contrast PLD exhibited little or no effect on the MDR cells. For the first time, these differences in in vitro efficacy are shown to be strongly correlated with cellular uptake and intracellular distribution of DOX brought about by DOX formulations (e.g., free solution, PLN vs PLD). To take into consideration the role of an intact immune system and tumor stroma in the response of host and tumor to chemotherapy, use was made of nonimmunocomprised mouse models to study the dose tolerance, cardiotoxicity, and efficacy of DOX-MMC coloaded PLN (DMsPLN) compared to PLD. DMsPLN treatment at 50 mg/m(2) DOX and 17 mg/m(2) of MMC singly or once every 4 days for 4 cycles were well tolerated by the mice without elevated systemic toxicity blood markers or myocardial damage. In contrast, PLD was limited to a single treatment due to significant total weight loss. The DMsPLN treatment delayed tumor growth up to 312% and 28% in EMT6/WT and EMT6/AR1 models, respectively. This work supports the translational value of DMsPLN for the aggressive management of either naïve or anthracycline-resistant tumors.

Carboxymethylcellulose-based and docetaxel-loaded nanoparticles circumvent P-glycoprotein-mediated multidrug resistance

Taxanes are a class of anticancer agents with a broad spectrum and have been widely used to treat a variety of cancer. However, its long-term use has been hampered by accumulating toxicity and development of drug resistance. The most extensively reported mechanism of resistance is the overexpression of P-glycoprotein (Pgp). We have developed a PEGylated carboxymethylcellulose conjugate of docetaxel (Cellax), which condenses into ∼120 nm nanoparticles. Here we demonstrated that Cellax therapy did not upregulate Pgp expression in MDA-MB-231 and EMT-6 breast tumor cells, whereas a significant increase in Pgp expression was measured with native docetaxel (DTX) treatment. Treatment with DTX led to 4-7-fold higher Pgp mRNA expression and 2-fold higher Pgp protein expression compared with Cellax treatment in the in vitro and in vivo system, respectively. Cellax also exhibited significantly increased efficacy compared with that of DTX in a taxane-resistant breast tumor model. Against the highly Pgp expressing EMT6/AR1 cells, Cellax exhibited a 6.5 times lower IC50 compared with that of native DTX, and in the in vivo model, Cellax exhibited 90% tumor growth inhibition, while native DTX had no significant antitumor activity.

Liposome-like Nanostructures for Drug Delivery

Liposomes are a class of well-established drug carriers that have found numerous therapeutic applications. The success of liposomes, together with recent advancements in nanotechnology, has motivated the development of various novel liposome-like nanostructures with improved drug delivery performance. These nanostructures can be categorized into five major varieties, namely: (1) polymer-stabilized liposomes, (2) nanoparticle-stabilized liposomes, (3) core-shell lipid-polymer hybrid nanoparticles, (4) natural membrane-derived vesicles, and (5) natural membrane coated nanoparticles. They have received significant attention and have become popular drug delivery platforms. Herein, we discuss the unique strengths of these liposome-like platforms in drug delivery, with a particular emphasis on how liposome-inspired novel designs have led to improved therapeutic efficacy, and review recent progress made by each platform in advancing healthcare.

Targeted delivery of doxorubicin through conjugation with EGF receptor-binding peptide overcomes drug resistance in human colon cancer cells

BACKGROUND AND PURPOSE

Induction of multidrug resistance by doxorubicin (DOX), together with non-specific toxicities, has restricted DOX-based chemotherapy. Recently, we demonstrated that DOX conjugated with an EGF receptor-binding peptide (DOX-EBP) had enhanced anticancer efficacy and reduced systemic toxicity when targeting EGF receptor-overexpressing tumours. Here we investigated whether DOX-EBP is able to overcome drug resistance and the underlying molecular mechanisms.

EXPERIMENTAL APPROACH

DOX-resistant SW480/DOX cells were derived from non-resistant SW480 cells by stepwise exposure to increasing concentrations of DOX, and P-glycoprotein overexpression induced by DOX was confirmed by Western blotting. Cytotoxicity and intracellular distribution of drugs were evaluated by MTT assay and fluorescence microscopy respectively. EGF receptor-mediated endocytosis was determined in EGF receptor and endocytosis inhibition assays. Drug accumulation in tumour cells and murine xenografts was determined by HPLC.

KEY RESULTS

The cytotoxicity and accumulation of DOX-EBP in SW480/DOX cells were almost the same as in SW480 cells, but those of free DOX were reduced. DOX-EBP accumulation was prevented by inhibitors of both EGF receptors and endocytosis, suggesting EGF receptors mediate endocytotic uptake. Tumour accumulation of DOX-EBP was significantly higher than free DOX in mice, and the levels of DOX-EBP were similar in DOX-resistant and non-resistant tumour tissues. Importantly, DOX-EBP, but not free DOX, was effective at inhibiting solid tumour growth and increased survival rate in both sensitive and resistant models.

CONCLUSION AND IMPLICATIONS

DOX-EBP can overcome DOX resistance of tumour cells and increase in vivo antitumour efficacy. Therefore, it has the potential to be a potent therapeutic agent for treating drug-resistant cancers.