Efficient Antitumor Drug Delivery Research Articles

Stimulus-responsive tea polyphenols as nanocarrier for selective intracellular drug delivery.

Nanodrug delivery systems have been widely researched to achieve efficient antitumor drug delivery. However, the controlled drug delivery at tumor cells remains the main challenge for antitumor therapy. Herein, a pH and reduction-responsive nanocarrier based on green tea polyphenols was employed as a smart excipient for chemotherapy drug delivery. Paclitaxel, as a chemotherapy drug, was loaded in the nanocarrier, noted as green tea polyphenol/paclitaxel. The green tea polyphenol/paclitaxel kept constant diameter at physiological condition (i.e. pH 7.4), while gradually enlarged at acid environment (pH = 5.5) and the reductive environment. The in vitro paclitaxel release results indicated that the release of paclitaxel from the green tea polyphenol/paclitaxel at pH 7.4 was slow, whereas obviously accelerated at the acid environment (pH = 5.5) and the reductive environment. The in vitro antitumor assay showed more efficient tumor cells inhibition of green tea polyphenol/paclitaxel than free paclitaxel. Meanwhile, due to the proper size (∼100 nm), green tea polyphenol/paclitaxel could effectively accumulate at tumor sites. In the in vivo mice bearing A549 xenograft mouse models, green tea polyphenol/paclitaxel exhibited satisfactory antitumor effect and depressed system toxicity when compared with free paclitaxel, owing to the enhanced paclitaxel accumulation and controlled paclitaxel release in the tumor cells. With simple compositions and satisfactory antitumor effects, this green tea polyphenol-based nanocarrier can be a promising nanodrug delivery system for the therapy of cancers.

Synergistic Chemotherapy for Breast Cancer and Breast Cancer Brain Metastases via Paclitaxel-Loaded Oleanolic Acid Nanoparticles.

Breast cancer is the most common type of cancer in women. About 12% of all women in the United States will be diagnosed with breast cancer over their lifetimes. At the same time, incidences of brain metastases (BMs) are increasing and represent an emerging health threat. However, there is no effective chemotherapy for breast cancer brain metastases (BCBMs), which is largely due to lack of efficient delivery of antitumor drugs or drug combinations to the brain. In this study, oleanolic acid (OA), a natural pentacyclic triterpenoid compound with excellent antitumor activity, was found to form nanoparticles (NPs) and efficiently penetrate the brain for BCBMs treatment. On the basis of these findings, we developed a synergistic combinatorial chemotherapeutic regimen by formulating paclitaxel (PTX) into OA NPs and demonstrated that the resulting PTX-OA NPs effectively inhibited primary breast cancer and BCBMs in mouse xenografts. Collectively, this study introduces a new direction to treat primary breast cancer and BCBMs through noninvasive combination chemotherapy.

Self-assembled pH-responsive polymeric nanoparticles based on lignin-histidine conjugate with small particle size for efficient delivery of anti-tumor drugs

As a natural biomaterial, lignin is mainly obtained from waste in the pulping and papermaking industry, and is becoming an alternative to petroleum-based chemicals. Lignin-based nanoparticles provide new possibilities for value-added utilization. In this work, a novel pH-responsive drug-loaded polymeric nanoparticle platform based on aminated lignin-histidine conjugate and 10-hydroxycamptothecin, AL-His/HCPT NP, is prepared by self-assembly. Based on the acidic microenvironment of tumor cells (endosomes: pH ∼5–6; lysosomes: pH ∼4–5), the AL-His/HCPT NPs are successfully imparted the pH-responsiveness by histidine, a pH-responsive small molecule to achieve triggered drug release. After 19 h of simulated release in vitro, the drug release amount of the nanoparticles was 39.1 % at pH 7.2, 63.1 % at pH 5.5, and 72.5 % at pH 4.5, indicating the pH-responsiveness. Meanwhile, the NPs have relatively small particle size (∼40 nm), which is key to anti-tumor nano-carriers. It is characterized by great biocompatibility, good drug loading performance (∼15.57 wt%), and effective cellular uptake (∼2 times that of pure HCPT). In 4T1 tumor-bearing mice model, the group treated with NPs shows excellent anti-tumor effect (tumor growth inhibition rate: ∼2 times that of pure HCPT) and reduced side effects. These results indicate that AL-His/HCPT NPs have great application prospects in drug delivery.

KHDRBS3 regulates the permeability of blood\u2013tumor barrier via cDENND4C/miR-577 axis

The existence of blood–tumor barrier (BTB) severely restricts the efficient delivery of antitumor drugs to cranial glioma tissues. Various strategies have been explored to increase BTB permeability. RNA-binding proteins and circular RNAs have recently emerged as potential regulators of endothelial cells functions. In this study, RNA-binding protein KH RNA-binding domain containing, signal transduction associated 3 (KHDRBS3) and circular RNA DENND4C (cDENND4C) were enriched in GECs. KHDRBS3 bound to cDENND4C and increased its stability. The knockdown of cDENND4C increased the permeability of BTB via downregulating the expressions of tight junction-related proteins. The miR-577 was lower expressed in GECs. The overexpressed miR-577 increased the permeability of BTB by reducing the tight junction-related protein expressions, and vice versa. Furthermore, cDENND4C acted as a molecular sponge of miR-577, which bound to miR-577 and inhibited its negative regulation of target genes ZO-1, occludin and claudin-1 to regulate BTB permeability. Single or combined treatment of KHDRBS3, cDENND4C, and miR-577 effectively promoted antitumor drug doxorubicin (DOX) across BTB to induce apoptosis of glioma cells. Collectively, the present study indicated that KHDRBS3 could regulate BTB permeability through the cDENND4C/miR-577 axis, which enhanced doxorubicin delivery across BTB. These findings may provide a novel strategy for chemotherapy of brain tumors.

Amphipathic β-cyclodextrin nanocarriers serve as intelligent delivery platform for anticancer drug

A novel glutathione-responsive (GSH-responsive) star-like amphiphilic polymer (C12H25)14-β-CD-(S-S-mPEG)7 (denoted as CCSP) was designed for efficient antitumor drug delivery. The amphiphilic β-cyclodextrin (β-CD) self-polymerize in water to form a sphere with a diameter of 40–50 nm. The secondary hydroxyl groups of β-CD were modified by dodecyl to form a hydrophobic core and the primary hydroxyl groups of β-CD were decorated with PEG through disulfide bond to form a hydrophilic shell. Since the hydrophobic cavity of β-CD was maintained, the hydrophobic core formed by dodecyl as well as cavity of β-CD provided CCSP with a loading content as high as 39.6 wt%. Importantly, DOX@CCSP exhibited low drug leakage and negligible cytotoxicity in non-reductive physiological environment, while it showed rapid release and high cytotoxicity in reductive tumorous environment via the breakage of disulfide bond. In view of the above-mentioned advantages of DOX@CCSP nanocarriers such as high loading content, proper size, favorable stimulus-response release performance and low leakage, it is believed that CCSP may offer great potential to be used as an intelligent nanocarrier for anticancer drug delivery.

Cisplatin‐Loaded Polymeric Micelles with Aggregation‐Induced Emission Feature for Cellular Imaging and Chemotherapy

AbstractImaging‐guided disease theranostic nanoplatforms based on polymeric micelles have drawn a broad attention because of their clear visualization, reduced systemic toxicity, enhanced utilization of drugs, and suppressed chemoresistance of tumors, which makes them possess potential application for cancer therapy. Herein, we synthesized a polymeric nanoparticles (Poly(MAD‐alt‐OCE)‐PTZ‐PEG) with novel aggregation‐induced emission (AIE) characteristic based on cheap commercial polymer by the simple and environmental method. These Poly(MAD‐alt‐OCE)‐PTZ‐PEG nanoparticles (NPs) show excellent biocompatibility and fluorescence property, which makes them huge application potential for cellular imaging. Furthermore, the antitumor drug cisplatin Pt(IV) can be loaded efficiently onto the surface of Poly(MAD‐alt‐OCE)‐PTZ‐PEG NPs due to the existence of abundant carboxyl groups on the NPs surface. The well‐controlled Pt(IV)‐loaded yield and great acid‐responsive drug release of these polymeriec micelles enhance cytotoxicity against cancer cells in vitro. Given the cheap raw materials, eco‐friendly method, excellent AIE property, efficient antitumor drug delivery and pH‐controlled drug release, these polymeric NPs would be a potential candidate for cancer diagnosis and therapy in the future.

Carboxymethyl cellulose-grafted graphene oxide for efficient antitumor drug delivery

Abstract A drug delivery system based on carboxymethyl cellulose-grafted graphene oxide loaded by methotrexate (MTX/CMC-GO) with pH-sensitive and controlled drug-release properties was developed in this work. CMC was grafted on graphene oxide by ethylenediamine through hydrothermal treatment. CMC serves as a pH-sensitive trigger, while CMC-GO serves as a drug-carrying vehicle due to the curved layer and large plain surface. Different amounts of drugs could be loaded into CMC-GO nanocarriers by control of the original amount of drug/carrier ratios. Additionally, low cytotoxicity against NIH-3T3 cells and low in vivo toxicity was observed. In vivo tumor growth inhibition assays showed that MTX/CMC-GO demonstrated superior antitumor activity than free MTX against HT-29 cells. Moreover, prolonged survival time of mice was observed after MTX/CMC-GO administration. The MTX/CMC-GO drug delivery system has a great potential in colon cancer therapy.

Temporary suppression the sequestrated function of host macrophages for better nanoparticles tumor delivery

Orchestration of nanoparticles to achieve targeting has become the mainstream for efficient delivery of antitumor drugs. However, the low delivery efficiency becomes the biggest barrier for clinical translation of cancer nanomedicines, as most of them are sequestrated in the liver where more macrophages located in are responsible for capture of systemic administrated nanoparticles. In this study, we found that the depletion of the liver macrophages could lead to a superior improvement in the nanoparticles delivery. Firstly, we developed clodronate-containing liposomes (clodrolip) to transiently suppress the phagocytic function of macrophages, the residual macrophages in liver only accounted for less than 1% when the mice were treated with clodrolip in advance. In addition, the pharmacokinetics results of treatment with paclitaxel-poly(lactic-co-glycolic acid) (PTX-PLGA) nanoparticles disclosed that the AUC of PTX in the macrophages depletion group increased 2.11-fold. These results meant that the removal of macrophages would decrease the nanoparticles accumulation in the liver and better the biodistribution and bioavailability of nanoparticles delivery systems. Moreover, treatment of mice with melanoma by the combination of clodrolip and PTX-PLGA nanoparticles resulted in an elevated anti-tumor efficacy, the tumor inhibition ratio was nearly reached to 80%. Furthermore, these combinatorial regimens have demonstrated negligible toxicity in incidence of adverse effects. In conclusion, the encouraging results from this study inspire the generation of a rational strategy to focus on microenvironmental priming for modulation of innate immunity and to improve delivery efficiency of nanoparticles.

Acid-activatable doxorubicin prodrug micelles with folate-targeted and ultra-high drug loading features for efficient antitumor drug delivery

Stimuli-responsive nanomedicine shows high therapeutic effects and low side effects to tumor cells and tissues, representing a preferable therapeutics for cancer therapy. Herein, we design an acid-stimuli-responsive doxorubicin polymeric prodrug (OM@DOX), and this amphiphilic prodrug has a unique chemical structure with prominent advantages, including high drug loading rate (as high as 61.5 wt%), pH-triggered drug release and targeted access to cells. This smart polymeric prodrug has a preferable size of ~40 nm and strong micellar stability in aqueous solution, which is benefited to the long blood circulation and efficient extravasation from tumor vessel. Moreover, the prodrug micelles showed a higher cytotoxicity against tumor cells (HeLa cells) than normal cells (L929 cells), likely suggesting the potential tumor-specific targeting ability. To render this prodrug micelles with targeting function, folic acid (FA) molecules conjugated prodrug (FA-OM@DOX) further showed selectively higher cytotoxicity to KB tumor cells (FA-receptor-positive) than A549 tumor cells (FA-receptor-negative). Considering the rapidly cell-penetrating ability and aforementioned features, we believe that the present prodrug strategy has the potential as a promising nanomedicine and providing inspired insights to design multifunctional drug delivery nanoplatforms.

Dual tumor-targeted poly(lactic-co-glycolic acid)-polyethylene glycol-folic acid nanoparticles: a novel biodegradable nanocarrier for secure and efficient antitumor drug delivery.

Further specific target-ability development of biodegradable nanocarriers is extremely important to promote their security and efficiency in antitumor drug-delivery applications. In this study, a facilely prepared poly(lactic-co-glycolic acid) (PLGA)–polyethylene glycol (PEG)–folic acid (FA) copolymer was able to self-assemble into nanoparticles with favorable hydrodynamic diameters of around 100 nm and negative surface charge in aqueous solution, which was expected to enhance intracellular antitumor drug delivery by advanced dual tumor-target effects, ie, enhanced permeability and retention induced the passive target, and FA mediated the positive target. Fluorescence-activated cell-sorting and confocal laser-scanning microscopy results confirmed that doxorubicin (model drug) loaded into PLGA-PEG-FA nanoparticles was able to be delivered efficiently into tumor cells and accumulated at nuclei. In addition, all hemolysis, 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium, and zebrafish-development experiments demonstrated that PLGA-PEG-FA nanoparticles were biocompatible and secure for biomedical applications, even at high polymer concentration (0.1 mg/mL), both in vitro and in vivo. Therefore, PLGA-PEG-FA nanoparticles provide a feasible controlled-release platform for secure and efficient antitumor drug delivery.

Fullerenol nanoparticles as a new delivery system for doxorubicin

Fullerenol as a promising intracellular targeting carrier for the efficient delivery of antitumor drugs into tumor cells.

Amphiphilic Diblock Terpolymer PMAgala-b-P(MAA-co-MAChol)s with Attached Galactose and Cholesterol Grafts and Their Intracellular pH-Responsive Doxorubicin Delivery.

In this work, a series of diblock terpolymer poly(6-O-methacryloyl-D-galactopyranose)-b-poly(methacrylic acid-co-6-cholesteryloxy hexyl methacrylate) amphiphiles bearing attached galactose and cholesterol grafts denoted as the PMAgala-b-P(MAA-co-MAChol)s were designed and prepared, and these terpolymer amphiphiles were further exploited as a platform for intracellular doxorubicin (DOX) delivery. First, employing a sequential RAFT strategy with preliminarily synthesized poly(6-O-methacryloyl-1,2:3,4-di-O-isopropylidene-d-galactopyranose) (PMAIpGP) macro-RAFT initiator and a successive trifluoroacetic acid (TFA)-mediated deprotection, a series of amphiphilic diblock terpolymer PMAgala-b-P(MAA-co-MAChol)s were prepared, and were further characterized by NMR, Fourier transform infrared spectrometer (FTIR), gel permeation chromatography (GPC), differential scanning calorimetry (DSC), and a dynamic contact angle testing instrument (DCAT). In aqueous media, spontaneous micellization of the synthesized diblock terpolymer amphiphiles were continuously examined by critical micellization concentration assay, dynamic light scattering (DLS), and transmission electron microscopy (TEM), and the efficacies of DOX loading by these copolymer micelles were investigated along with the complexed nanoparticle stability. Furthermore, in vitro DOX release of the drug-loaded terpolymer micelles were studied at 37 °C in buffer under various pH conditions, and cell toxicities of as-synthesized diblock amphiphiles were examined by MTT assay. Finally, with H1299 cells, intracellular DOX delivery and localization by the block amphiphile vectors were investigated by invert fluorescence microscopy. As a result, it was revealed that the random copolymerization of MAA and MAChol comonomers in the second block limited the formation of cholesterol liquid-crystal phase and enhanced DOX loading efficiency and complex nanoparticle stability, that ionic interactions between the DOX and MAA comonomer could be exploited to trigger efficient DOX release under acidic condition, and that the diblock terpolymer micellular vector could alter the DOX trafficking in cells. Hence, these suggest the pH-sensitive PMAgala-b-P(MAA-co-MAChol)s might be further exploited as a smart nanoplatform toward efficient antitumor drug delivery.

Charge-Conversional PEG-Polypeptide Polyionic Complex Nanoparticles from Simple Blending of a Pair of Oppositely Charged Block Copolymers as an Intelligent Vehicle for Efficient Antitumor Drug Delivery

A tumor-acidity-activated charge-conversional polyionic complex nanoparticle system was developed by simply mixing a pair of oppositely charged block copolymers: anionic methoxy poly(ethylene glycol)-b-poly(l-glutamic acid-co-l-phenylalanine) (mPEG-b-P(Glu-co-Phe)) and cationic methoxy poly(ethy1ene glycol)-b-poly(l-lysine-co-l-phenylalanine) (mPEG-b-P(Lys-co-Phe)). The nanoparticles could stay negatively charged under normal physiological pH value and reverse the surface charge to positive at the tumor extracellular environment. Doxorubicin (DOX) was encapsulated into the nanoparticles fabricated by a self-assembly process, and the DOX-loaded polyionic complex nanoparticles (DOX-NPs) retained the charge-conversional property. In vitro DOX release study demonstrated that DOX release was promoted by the significantly increased acidity in endosomes and lysosomes (pH ≈ 5-6). Cellular uptake studies confirmed that the DOX-NPs could be more effectively internalized by cells at the tumor extracellular pH value. In vitro cytotoxicity assays demonstrated that the polyionic complex nanoparticles had good biocompatibility, and DOX-NPs showed efficient cell proliferation inhibition to HeLa and A549 tumor cells. Maximum tolerated dose (MTD) studies revealed that DOX-NPs had a significantly higher MTD (more than 25 mg of DOX/kg) in mice compared to that for free DOX (5 mg of DOX/kg). Furthermore, DOX-NPs showed superior antitumor activity and reduced side toxicity compared to free DOX in A549 tumor bearing nude mice.

Improved tumor targetability of Tat-conjugated PAMAM dendrimers as a novel nanosized anti-tumor drug carrier

The generation 4-poly-amidoamine-dendrimers (PAMAM G4 dendrimer, P) was conjugated to Tat peptide (Tat, T), a cell-penetrating peptide, in search of an efficient anti-tumor drug delivery vehicle for cancer therapy. In this study, we synthesized BODIPY-labeled Tat-Conjugated PAMAM dendrimers (BPTs) as a novel nanosized anticancer drug carriers and systemically investigated their biodistribution and the tumor accumulation in Sarcoma 180-bearing mice. In addition, the uptake and the cytotoxicity to S180 cells of BPTs thereof were evaluated. The unmodified dendrimer (BP) showed a soon clearance from the blood stream and nonspecific accumulation in tumor. In contrast, the Tat-modified dendrimer, BPT(64) with appropriate particle size showed a better retention in blood and could be accumulated effectively in tumor tissue via the enhanced permeability and retention (EPR) effect. Moreover, BPTs with a high Tat modification rate was accumulated more effectively in tumor tissue. In vitro experiments, these BPTs displayed low cytotoxicity on S180 cells and high uptake to S180 cells. These findings indicate that the nanoparticulate system on the basis of Tat-conjugated PAMAM dendrimers is safer and effective in the concentration range (below 20 μg/ml) to be used as a carrier of anti-tumor drugs for tumor targeting by intravenous administration.

Dual Targeted Polymeric Nanoparticles Based on Tumor Endothelium and Tumor Cells for Enhanced Antitumor Drug Delivery

Some specific types of tumor cells and tumor endothelial cells represented CD13 proteins and act as receptors for Asn-Gly-Arg (NGR) motifs containing peptide. These CD13 receptors can be specifically recognized and bind through the specific sequence of cyclic NGR (cNGR) peptide and presented more affinity and specificity toward them. The cNGR peptide was conjugated to the poly(ethylene glycol) (PEG) terminal end in the poly(lactic-co-glycolic) acid PLGA-PEG block copolymer. Then, the ligand conjugated nanoparticles (cNGR-DNB-NPs) encapsulating docetaxel (DTX) were synthesized from preformed block copolymer by the emulsion/solvent evaporation method and characterized for different parameters. The various studies such as in vitro cytotoxicity, cell apoptosis, and cell cycle analysis presented the enhanced therapeutic potential of cNGR-DNB-NPs. The higher cellular uptake was also found in cNGR peptide anchored NPs into HUVEC and HT-1080 cells. However, free cNGR could inhibit receptor mediated intracellular uptake of NPs into both types of cells at 37 and 4 °C temperatures, revealing the involvement of receptor-mediated endocytosis. The in vivo biodistribution and antitumor efficacy studies indicated that targeted NPs have a higher therapeutic efficacy through targeting the tumor-specific site. Therefore, the study exhibited that cNGR-functionalized PEG-PLGA-NPs could be a promising approach for therapeutic applications to efficient antitumor drug delivery.

Octreotide-Modified N-Octyl-O, N-Carboxymethyl Chitosan Micelles as Potential Carriers for Targeted Antitumor Drug Delivery

Octreotide (OCT) was recently found to have high binding affinity to the positive tumor cells of somatostatin receptors (SSTRs). In this study, octreotide-Phe-polyethylene glycol-stearic acid was first successfully synthesized and used as a targeting molecule for N-octyl-O, N-carboxymethyl chitosan (OCC). Doxorubicin (DOX) was loaded into OCT-modified OCC micelles (DOX-OCC-OCT). The drug-loaded micelles obtained exhibited spherical shape, small particle sizes, and negative zeta potentials. The cytotoxicity of DOX-OCC-OCT micelles against MCF-7 cells (SSTRs expressing) was found to significantly increase with the increased amount of OCT modification, whereas no significant difference was observed against WI-38 cells (no SSTRs expressing). Results of flow cytometry, fluorescence microscopy, and confocal laser scanning microscopy confirmed that DOX-OCC-OCT micelles could remarkably increase the uptake of DOX in MCF-7 cells. All the results indicated that OCC-OCT micelles may be a promising intracellular targeting carrier for efficient delivery of antitumor drugs into tumor cells.