Active Targeting Drug Research Articles

Tumor Microenvironment and Angiogenic Blood Vessels Dual-Targeting for Enhanced Anti-Glioma Therapy.

Advances in active targeting drug delivery system (DDS) have revolutionized glioma diagnosis and therapy. However, the lack of the sufficient targets on glioma cells and limited penetration capability of DDS have significantly compromised the treatment efficacy. In this study, by taking advantages of the abundant extracellular matrix-derived heparan sulfate proteoglycan (HSPG) and enhanced tumor penetration ability mediated by neuropilin-1 (NRP-1) protein, we reported the ATWLPPR and CGKRK peptide dual-decorated nanoparticulate DDS (designated AC-NP) to achieve angiogenic blood vessels and tumor microenvironment dual-targeting effect. The resulted AC-NP displayed the particle size of 123 ± 19.47 nm. Enhanced cellular association of AC-NP was achieved on HUVEC cells and U87MG cells. AC-NP was internalized via caveolin- and lipid raft-mediated mechanism with the involvement of energy and lysosome in HUVEC cells and via caveolin- and lipid raft-mediated pathway with the participation of energy, microtubulin, and lysosome in U87MG cells. After loading with anticancer drug, paclitaxel (PTX), the enhanced apoptosis induction and antiproliferative activity were achieved by AC-NP. Furthermore, in vitro U87MG tumor spheroids assays showed a deeper penetration and an enhanced inhibitory effect against the U87MG tumor spheroids achieved by AC-NP. In vivo animal experiment showed that decoration of AC peptide on the nanoparticulate DDS resulted in extensive accumulation at glioma site and improved anti-glioma efficacy. Collectively, the results suggested that AC-NP holds great promise to serve as an effective tumor blood vessel and tumor microenvironment dual-targeting DDS with enhanced penetration capability, holding great potential in improving anti-glioma efficacy.

Identification of a Nucleoporin358-Specific RNA Aptamer for Use as a Nucleus-Targeting Liposomal Delivery System.

An active targeting drug delivery system that targets the nucleus could solve the problem of the treatment of genetic disorders through gene delivery, but it has met with limited success. The purpose of this study was to establish an RNA aptamer-modified nucleus-targeting liposomal carrier system referred to as NupApt-liposomes. RNA aptamers against the Nup358 protein are prepared using a newly established Protein SELEX method. After confirming aptamer binding to the recombinant protein, an aptamer-lipid conjugate (Apt-PEG-DSPE) was prepared. Aptamer-modified liposomes and simple polyethylene glycol (PEG) liposomes were prepared to check its ability to bind to isolated nuclei. Confocal studies indicated that the aptamer-modified liposomes had the ability to bind to isolated nuclei, whereas PEG-liposomes showed only weak binding. Confocal laser scanning microscopy studies of inhibition assays also supported the above conclusion. The dissociation constant of the Nucleoporin358-specific aptamer referred to as NupApt01 and NupApt02 were 36 and 70 nM, respectively. Finally, with aptamer-modified liposomes, gene expression studies showed a two times better gene expression in NupApt-liposome-treated nuclei in comparison to that of PEG-liposomes. This represents the first artificial RNA aptamer-modified liposomes promoting the specific binding of a nanocarrier to the nucleus, thus improving gene expression in comparison to PEG-liposomes.

Reversing Cancer Multidrug Resistance in Xenograft Models via Orchestrating Multiple Actions of Functional Mesoporous Silica Nanoparticles.

A multistimuli responsive drug delivery system (DDS) based on sulfhydryl and amino-cofunctionalized mesoporous silica nanoparticles (SH/NH2-MSNs) has been developed, in which the multifunctional hyaluronic acid (HA) derivatives were grafted onto the SH/NH2-MSNs by disulfide bonds for targeting delivery, controlling drug release and reversing multidrug resistance (MDR). The doxorubicin (Dox) loaded multifunctional HA derivatives modified mesoporous silica nanoparticles (Dox/HHS-MSNs) were enzyme and redox sensitive, which could respond to the intracellular stimuli of hyaluronidase (HAase) and glutathione (GSH) successively and prevent drug leakage before reaching the tumor tissues. The cellular uptake experiments showed that Dox/HHS-MSNs were vulnerable to be endocytosed into the Dox-resistant human breast adenocarcinoma (MCF-7/ADR) cells, efficiently realized the endolysosomal escape and remained in the cytoplasm. Because of orchestrating multiple actions above including active targeting, endolysosomal escape and efficient multilevel drug release, Dox/HHS-MSNs could induce the strongest apoptosis and cytotoxicity of MCF-7/ADR cells. Furthermore, a series of in vivo studies on MCF-7/ADR tumor-bearing xenograft mouse models demonstrated that Dox/HHS-MSNs possessed the enhanced tumor-targeting capacity and the best therapeutic efficacy to reverse cancer MDR.

Design of smart GE11-PLGA/PEG-PLGA blend nanoparticulate platforms for parenteral administration of hydrophilic macromolecular drugs: synthesis, preparation and in vitro/ex vivo characterization

Active drug targeting and controlled release of hydrophilic macromolecular drugs represent crucial points in designing efficient polymeric drug delivery nanoplatforms. In the present work EGFR-targeted polylactide-co-glycolide (PLGA) nanoparticles were made by a blend of two different PLGA-based polymers. The first, GE11-PLGA, in which PLGA was functionalized with GE11, a small peptide and EGFR allosteric ligand, able to give nanoparticles selective targeting features. The second polymer was a PEGylated PLGA (PEG-PLGA) aimed at improving nanoparticles hydrophilicity and stealth features. GE11 and GE11-PLGA were custom synthetized through a simple and inexpensive method. The nanoprecipitation technique was exploited for the preparation of polymeric nanoparticles composed by a 1:1weight ratio between GE11-PLGA and PEG-PLGA, obtaining smart nanoplatforms with proper size for parenteral administration (143.9±5.0nm). In vitro cellular uptake in EGFR-overexpressing cell line (A549) demonstrated an active internalization of GE11-functionalized nanoparticles. GE11-PLGA/PEG-PLGA blend nanoparticles were loaded with Myoglobin, a model hydrophilic macromolecule, reaching a good loading (2.42% respect to the theoretical 4.00% w/w) and a prolonged release over 60days. GE11-PLGA/PEG-PLGA blend nanoparticles showed good in vitro stability for 30days in physiological saline solution at 4°C and for 24h in pH 7.4 or pH 5.0 buffer at 37°C respectively, giving indications about potential storage and administration conditions. Furthermore ex vivo stability study in human plasma using fluorescence Single Particle Tracking (fSPT) assessed good GE11-PLGA/PEG-PLGA nanoparticles dimensional stability after 1 and 4h. Thanks to the versatility in polymeric composition and relative tunable nanoparticles features in terms of drug incorporation and release, GE11-PLGA/PEG-PLGA blend NPs can be considered highly promising as smart nanoparticulate platforms for the treatment of diseases characterized by EGFR overexpression by parenteral administration .

Somatostatin Receptor-Mediated Tumor-Targeting Nanocarriers Based on Octreotide-PEG Conjugated Nanographene Oxide for Combined Chemo and Photothermal Therapy.

Nano-sized in vivo active targeting drug delivery systems have been developed to a high anti-tumor efficacy strategy against certain cancer-cells-specific. Graphene based nanocarriers with unique physical and chemical properties have shown significant potentials in this aspect. Here, octreotide (OCT), an efficient biotarget molecule, is conjugated to PEGylated nanographene oxide (NGO) drug carriers for the first time. The obtained NGO-PEG-OCT complex shows low toxicity and excellent stability in vivo and is able to achieve somatostatin receptor-mediated tumor-specific targeting delivery. Owing to the high loading efficiency and accurate targeting delivery of anti-cancer drug doxorubicin (DOX), our DOX loaded NGO-PEG-OCT complex offers a remarkably improved cancer-cell-specific cellular uptake, chemo-cytotoxicity, and decreased systemic toxicity compared to free DOX or NGO-PEG. More importantly, due to its strong near-infrared absorption, the NGO-PEG-OCT complex further enhances efficient photothermal ablation of tumors, delivering combined chemo and photothermal therapeutic effect against cancer cells.

Aptamer-Functionalized and Backbone Redox-Responsive Hyperbranched Polymer for Targeted Drug Delivery in Cancer Therapy.

A novel type of backbone redox-responsive hyperbranched poly(2-((2-(acryloyloxy)ethyl)disulfanyl)ethyl 4-cyano-4-(((propylthio)carbonothioyl)-thio)-pentanoate-co-poly(ethylene glycol) methacrylate) (HPAEG) has been designed and prepared successfully via the combination of reversible addition-fragmentation chain-transfer (RAFT) polymerization and self-condensing vinyl polymerization (SCVP). Owing to the existence of surface vinyl groups, HPAEG could be efficiently functionalized by DNA aptamer AS1411 via Michael addition reaction to obtain an active tumor targeting drug delivery carrier (HPAEG-AS1411). The amphiphilic HPAEG-AS1411 could form nanoparticles by macromolecular self-assembly strategy. Cell Counting Kit-8 (CCK-8) assay illustrated that HPAEG-AS1411 nanoparticles had low cytotoxicity to normal cell line. Flow cytometry and confocal laser scanning microscopy (CLSM) results demonstrated that HPAEG-AS1411 nanoparticles could be internalized into tumor cells via aptamer-mediated endocytosis. Compared with pure HPAEG nanoparticles, HPAEG-AS1411 nanoparticles displayed enhanced tumor cell uptake. When the HPAEG-AS1411 nanoparticles loaded with anticancer drug doxorubicin (DOX) were internalized into tumor cells, the disulfide bonds in the backbone of HPAEG-AS1411 were cleaved by glutathione (GSH) in the cytoplasm, so that DOX was released rapidly. Therefore, DOX-loaded HPAEG-AS1411 nanoparticles exhibited a high tumor cellular proliferation inhibition rate and low cytotoxicity to normal cells. This aptamer-functionalized and backbone redox-responsive hyperbranched polymer provides a promising platform for targeted drug delivery in cancer therapy.

Lymphatic Targeting of Nanosystems for Anticancer Drug Therapy.

The lymphatic system represents a major route of dissemination in metastatic cancer. Given the lack of selectivity of conventional chemotherapy to prevent lymphatic metastasis, in the last years there has been a growing interest in the development of nanocarriers showing lymphotropic characteristics. The goal of this lymphotargeting strategy is to facilitate the delivery of anticancer drugs to the lymph node-resident cancer cells, thereby enhancing the effectiveness of the anti-cancer therapies. This article focuses on the nanosystems described so far for the active or passive targeting of oncological drugs to the lymphatic circulation. To understand the design and performance of these nanosystems, we will discuss first the physiology of the lymphatic system and how physiopathological changes associated to tumor growth influence the biodistribution of nanocarriers. Second, we provide evidence on how the tailoring of the physicochemical characteristics of nanosystems, i.e. particle size, surface charge and hydrophilicity, allows the modulation of their access to the lymphatic circulation. Finally, we provide an overview of the relationship between the biodistribution and antimetastatic activity of the nanocarriers loaded with oncological drugs, and illustrate the most promising active targeting approaches investigated so far.

Recent Innovations in Cancer Chemotherapy by Nanomedicines

Background: Various drug delivery systems of antitumor drugs have been developed for past several decades. Nanomedicines, being one of promising choices, have been attracting much attention for the purpose of improving clinical use; because, they sometimes exhibit superior potentiality of enhanced efficacy and reduction of toxicity. Recently, many nanomedicines have been found to have useful results in the preclinical studies, and reached clinical trials or clinically-available stages. As there are few overviews for such situation, the brief explanation of such promising nanomedicines has been performed in this review. Methods: we focused on several types of antitumor drugs, therapeutic features of which were improved extensively by nano-technological approaches. As to each antitumor drug, physicochemical and antitumor characteristics and improved points in nanomedicines were briefly introduced by referring to main papers and patents. Results: Promising nanomedicines have been recently developed for doxorubicin, epirubicin, paclitaxel, cisplatin, oxaliplatin and SN-38, and they are now being in clinical trials or clinically used. The pharmacokinetic features are drastically improved in nanomedicines as compared with original drugs, leading to enhanced efficacy and reduced toxicity. The major reason is by passive drug targeting based on enhanced permeability and retention (EPR) effect. At this late date, as antibody/drug conjugate micelles were found to show superior antitumor efficacy, active drug targeting nanomedicines are expected as novel nanomedicines toward clinical use. Conclusion: This review made clear recent situations of promising nanomedicines of antitumor drugs. The concept of nanomedicines has been demonstrated to be a useful strategy because several of them have reached clinical stage. Nanomedicines with potential of passive targeting or active targeting are expected as superior cancer chemotherapy. Keywords: Clinical trial, key anticancer drug, nanodevice, nanomedicine.

In vitro and in vivo anti-tumor characterizations of β-elemene-loaded nanoemulsion

active targeting drug delivery. Herein LyP-1 peptide was used as a model peptide to verify this phenomenon. LyP-1, a short peptide cyclized with a disulfide bond, can specifically bind to tumor cells through the interaction with cell-surface protein p32/gC1qR. It has been frequently used as a ligand for designing tumor targeted drug delivery systems. However, the instability of disulfide bond limits its potential efficiency. In the present research, we mutated the C-terminal Cys to Ala and cyclized the peptide with an amide bond using native chemical ligation technique. The new cyclic LyP-1 peptide, termed c(LyP-1), has been compared with LyP-1 for their biological functions in cellular levels. Because of the substitution of cyclization from disulfide bond to amide bond, c(LyP-1) modified liposomes showed 3 times enhancement of in vitro targeting capacity to tumor cells when compared with that of LyP-1.

Value of Functionalized Superparamagnetic Iron Oxide Nanoparticles in the Diagnosis and Treatment of Acute Temporal Lobe Epilepsy on MRI.

Purpose. Although active targeting of drugs using a magnetic-targeted drug delivery system (MTDS) with superparamagnetic iron oxide nanoparticles (SPIONs) is a very effective treatment approach for tumors and other illnesses, successful results of drug-resistant temporal lobe epilepsy (TLE) are unprecedented. A hallmark in the neuropathology of TLE is brain inflammation, in particular the activation of interleukin-1β (IL-1β) induced by activated glial cells, which has been considered a new mechanistic target for treatment. The purpose of this study was to determine the feasibility of the functionalized SPIONs with anti-IL-1β monoclonal antibody (mAb) attached to render MRI diagnoses and simultaneously provide targeted therapy with the neutralization of IL-1β overexpressed in epileptogenic zone of an acute rat model of TLE. Experimental Design. The anti-IL-1β mAb-SPIONs were studied in vivo versus plain SPIONs and saline. Lithium-chloride pilocarpine-induced TLE models (n = 60) were followed by Western blot, Perl's iron staining, Nissl staining, and immunofluorescent double-label staining after MRI examination. Results. The magnetic anti-IL-1β mAb-SPION administered intravenously, which crossed the BBB and was concentrated in the astrocytes and neurons in epileptogenic tissues, rendered these tissues visible on MRI and simultaneously delivered anti-IL-1β mAb to the epileptogenic focus. Conclusions. Our study provides the first evidence that the novel approach enhanced accumulation and the therapeutic effect of anti-IL-1β mAb by MTDS using SPIONs.

Stability Indicating RP-HPLC Method for In-Vitro Analysis of 5-Flurouracil

5-Flurouracil (FU), {5-fluoropyrimidines-2, 4(1H, 3H)-dione} is an anticancer drug that competitively inhibits thymidylate synthatase, an enzyme required for DNA synthesis that leads to programmed cell death of proliferating cells. It is used as topical cream for squamous cell carcinoma but a little information is available for its active drug targeting. Our attempt is to generate a validated stability indicating RP-HPLC method for the quantitation of 5-FU for active targeting to squamous cell carcinoma. In our study, RP-HPLC system used was (SHIMADZU (AT vp), Japan) and comprised of UV detector (SCL-10A vp), a pump system (LC-10 AT vp), and an injector. The separation was achieved on C18 LiChrospher®100 (250 x 4.6 mm, 5 μm) and elution was monitored gradiently with mobile phase consisting of HPLC water at a flow rate of 1ml/min. The injection volume was 20 μL previously filtered through 0.45μ membrane filter and elute was analyzed at the set wavelength of 269 nm. The proposed method was validated for various parameters such as specificity, linearity, precision, accuracy, and robustness. The calibration plot drawn was found to be linear over the concentration range of 1–10μg/mL and within the acceptable range (R2 = 0.999). The developed method was found to be simple, precise, and accurate and can be reproduced with LOD and LOQ of 0.007108 and 0.021539μg/mL respectively. The degradation study at variable temperatures such as 0°C; 8°C, 25°C, 37°C and pH 1.2, 3.2, 4.2, 6.8 and 7.4 after storage for 24 h suggested that 5-FU was stable at aforementioned temperatures and pH. It further signifies that the method is suitable for in-process quality control analysis of new composition of 5-FU due to good accuracy and high degree of precision.

Oseltamivir-conjugated polymeric micelles prepared by RAFT living radical polymerization as a new active tumor targeting drug delivery platform.

Targeted drug delivery using polymeric nanostructures has been at the forefront of cancer research, engineered for safer, more efficient and effective use of chemotherapy. Here, we designed a new polymeric micelle delivery system for active tumor targeting followed by micelle-drug internalization via receptor-induced endocytosis. We recently reported that oseltamivir phosphate targets and inhibits Neu1 sialidase activity associated with receptor tyrosine kinases such as epidermal growth factor receptors (EGFRs) which are overexpressed in cancer cells. By decorating micelles with oseltamivir, we investigated whether they actively targeted human pancreatic PANC1 cancer cells. Amphiphilic block copolymers with oseltamivir conjugated at the hydrophilic end, oseltamivir-pPEGMEMA-b-pMMA (oseltamivir-poly(polyethylene glycol methyl ether methacrylate)-block-poly(methyl methacrylate), were synthesized using reversible addition-fragmentation chain transfer (RAFT) living radical polymerization. Oseltamivir-conjugated micelles have self-assembling properties to give worm-like micellar structures with molecular weight of 80 000 g mol(-1). Oseltamivir-conjugated water soluble pPEGMEMA, dose dependently, both inhibited sialidase activity associated with Neu1, and reduced viability of PANC1 cells. In addition, oseltamivir-conjugated micelles, labelled with a hydrophobic fluorescent dye within the micelle core, were subsequently internalized by PANC1 cells. Blocking cell surface Neu1 with anti-Neu1 antibody, reduced internalization of oseltamivir-conjugated micelles, demonstrating that Neu1 binding linked to sialidase inhibition were prerequisite steps for subsequent internalization of the micelles. The mechanism of internalization is likely that of receptor-induced endocytosis demonstrating potential as a new nanocarrier system for not only targeting a tumor cell, but also for directly reducing viability through Neu1 inhibition, followed by intracellular delivery of hydrophobic cytotoxic chemotherapeutics.

Platelet-like proteoliposomes enable active drug delivery to infarcted heart tissue

Platelet-like proteoliposomes enable active drug delivery to infarcted heart tissue

TKD peptide as a ligand targeting drug delivery systems to memHsp70-positive breast cancer

Breast cancer has been considered as a serious threat to females’ life. Active targeting drug delivery is a potential strategy in cancer therapy, which however is hindered by the targeting efficiency. Herein, a 14-mer peptide (TKD) derived from the oligomerization domain of membrane heat-shock protein 70 (memHsp70), for the first time, was exploited as a tumor-targeting ligand to modify polymeric micelles. NMR results demonstrated the successful synthesis of TKD-PEG-PLGA polymer. No difference was observed in the drug release between TKD-modified doxorubicin (DOX)-loaded micelles (TKD-D-M) and unmodified counterparts. The modification of TKD mediated apparently higher cellular uptake within memHsp70-positive MCF-7 cells, compared to normal MCF-10A cells. Excessive TKD pretreatment significantly inhibited the cellular uptake of TKD-D-M, indicating the receptor-mediated mechanism. Enhanced accumulation of TKD-D-M within the tumor of MCF-7 bearing mice further demonstrated the targeting ability of TKD in vivo. CCK-8 assay showed that the modification of TKD significantly increase the anti-proliferation effect against MCF-7 cells. The findings demonstrated that TKD peptide is a potential ligand which can target drug delivery systems to memHsp70-positive breast cancer.

Chitosan-based hydrogel nanoparticle amazing behaviors during transmission electron microscopy

Nanogels are potential polymeric nanoparticulate systems of interest in biomedical applications, including time-controlled drug delivery and active drug targeting. With the aim of preparation of a nanocarrier for brain enhancement of the BBB-restricted hydrophilic drugs, nanogel loaded with the antineoplasm drug, methotrexate was prepared using an ionic gelation process. During transmission electron microscopy imaging, hydrogel nanoparticles were found as a polymeric matrix containing aqueous vacuoles. With emitting the electrons and increase in energy intake, the vacuoles were interconnected and form a large one. Then the volume of the new vacuole grew and subsequently decreased over the time. The behavior was in good agreement with drug release kinetic findings. These results provide important guidelines for designing top-down fabricated hydrogel nanoparticles with specific drug release kinetic mechanisms for enhancing and predicting the drug delivery efficacy.

CRGDyK modified pH responsive nanoparticles for specific intracellular delivery of doxorubicin

Stimuli-responsive nanocarriers attract wide attention because of the unique differences in microenvironment between solid tumors and normal tissues. Herein, we reported a novel cRGDyK peptide modified pH-sensitive nanoparticle system based on poly(ethylene glycol)-poly(2,4,6-trimethoxy benzylidene-pentaerythritol carbonate) (PEG-PTMBPEC) diblock copolymer, which was expected to destroy tumor angiogenesis and kill tumor cells simultaneously. Doxorubicin (DOX)-loaded nanoparticles (NPs) were characterized to have a uniform size distribution, high entrapment efficiency, good stability in plasma as well as a pH dependent drug release pattern. Blank NPs were non-toxic to both tumor cells and normal cells, while DOX-loaded cRGDyK peptide modified NPs (cRGDyK-NPs) exhibited the pronounced cytotoxicity against B16 cells and human umbilical vein endothelial cells (HUVEC) overexpressing αvβ3 integrin receptors. Cellular uptake studies revealed that the highly efficient uptake of cRGDyK-NPs was attributed to the receptor-mediated endocytosis and acidic-triggered drug release. Importantly, cRGDyK-NPs could dramatically reduce the systemic toxicity of DOX and exert excellent tumor killing activity in vivo. The cRGDyK modified pH-sensitive nanocarrier is a promising vehicle for intracellular drug delivery to αvβ3 integrin receptor overexpressed tumor cells and neovascular cells. Statement of SignificanceSlow intracellular drug release and poor tumor targeting capacity are still the critical barriers of polymeric nanoparticles (NPs) for the treatment efficiency of chemotherapy. In the present study, we designed cRGDyK peptide modified poly(ethylene glycol)-poly(2,4,6-trimethoxybenzylidene-pentaerythritol carbonate) (cRGDyK-PEG-PTMBPEC) NPs with active targeting and fast pH-triggered drug release. Doxorubicin (DOX)-loaded cRGDyK-PEG-PTMBPEC NPs exhibited pronounced cytotoxicity and enhanced cellular uptake against B16 cells and human umbilical vein endothelial cells overexpressing αvβ3 integrin receptors. Moreover, the active targeted pH-sensitive NPs can enhance the antitumor activity and reduce the systematic toxicity of DOX in vivo.

Enzyme-triggered, cell penetrating peptide-mediated delivery of anti-tumor agents

Conventional chemotherapy has little or no specificity for cancer cells, normally resulting in low drug accumulation at the tumor region (inefficacy) and drug-induced severe side effects (toxicity). Nowadays, new strategies have been developed to improve both the targeting ability and cellular drug uptake using active targeting ligands and drug internalization agents, which could recognize and interact with specific receptors overexpressed on tumor cells and then trigger a drug internalization process by transporting the cargos into cells. Among those strategies, enzyme-triggered cell penetrating peptide (CPP)-mediated systems seem to be a feasible approach. The expression level of specific enzymes like proteases, esterases or glycosidases is often higher in tumor cells than in normal tissues, and such concentration gradients can be exploited as a tool for targeted cancer therapy. CPPs are known to be effective in promoting membrane transportation of the drug cargos, rendering a deeper tumor permeation that could further enhance the therapeutic efficacy of the delivered drug. An enzyme-triggered, CPP-mediated system would combine these advantages to yield a system with the enhanced tumor targeting ability and internalization efficiency and so far many systems have been successfully exploited and applied to cancer therapy. In this review, typical enzymes applied in cancer theranostic systems were firstly reviewed, followed by analyzing pros and cons of cell penetrating peptides. Most importantly, different types of applications of enzyme-triggered CPP-mediated systems in tumor imaging were illustrated. Finally, the drug loaded applications, i.e. enzyme-triggered CPP-mediated systems in drug delivery were reviewed.

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.

Intracellular delivery and antitumor effects of a redox-responsive polymeric paclitaxel conjugate based on hyaluronic acid

Polymer–drug conjugates have demonstrated application potentials in optimizing chemotherapeutics. In this study a new bioconjugate, HA-ss-PTX, was designed and synthesized with cooperative dual characteristics of active tumor targeting and selective intracellular drug release. Paclitaxel (PTX) was covalently attached to hyaluronic acid (HA) with various sizes (MW 9.5, 35, 770kDa); a cross-linker containing disulfide bond was also used to shield drug leakage in blood circulation and to achieve rapid drug release in tumor cells in response to glutathione. Incorporation of HA to the conjugate enhanced the capabilities of drug loading, intracellular endocytosis and tumor targeting of micelles in comparison to mPEG. HA molecular weight showed significant effect on properties and antitumor efficacy of the synthesized conjugates. Intracellular uptake of HA-ss-PTX toward MCF-7 cells was mediated by CD44-caveolae-mediated endocytosis. Compared to Taxol and mPEG-ss-PTX, HA9.5-ss-PTX demonstrated improved tumor growth inhibition in vivo with a TIR of 83.27±5.20%. It was concluded that HA9.5-ss-PTX achieved rapid intracellular release of PTX and enhanced its therapeutic efficacy, thus providing a platform for specific drug targeting and controlled intracellular release in chemotherapeutics. Statement of SignificancePolymer–drug conjugates, promising nanomedicines, still face some technical challenges including a lack of specific targeting and rapid intracellular drug release at the target site. In this manuscript we designed and constructed a novel bioconjugate HA-ss-PTX, which possessed coordinated dual characteristics of active tumor targeting and selective intracellular drug release. Redox-responsive disulfide bond was introduced to the conjugate to shield drug leakage in blood circulation and to achieve rapid drug release at tumor site in response to reductant like glutathione. Paclitaxel was selected as a model drug to be covalently attached to hyaluronic acid (HA) with various sizes to elucidate the structure–activity relationship and to address whether HA could substitute PEG as a carrier for polymeric conjugates. Based on a series of in vitro and in vivo experiments, HA-ss-PTX performed well in drug loading, cellular internalization, tumor targeting by entering tumor cells via CD44-caveolae-mediated endocytosis and rapidly release drug at target in the presence of GSH. One of the key issues in clinical oncology is to enhance drug delivery efficacy while minimizing side effects. The study indicated that this new polymeric conjugate system would be useful in delivering anticancer agents to improve therapeutic efficacy and to minimize adverse effects, thus providing a platform for specific drug targeting and controlled intracellular release in chemotherapeutics.

Doxorubicin-Loaded Micelles Based on Folic Acid Conjugated pH-Dependent Thermo-Sensitive Copolymer: <I>In Vitro</I> and <I>In Vivo</I> Evaluation

In this paper, the doxorubicin (DOX)-loaded micelles were prepared based on a novel folic acid conjugated pH-dependent thermo-sensitive copolymer poly(D,L-lactic acid)-b-poly(N-isopropyl methacrylamide-co-N-isopropylmaelic acid-co-10-undecenoic acid) (PLA-PNNUA-FA) constructed to provide an active targeting drug delivery and triggered drug release system. The micelles were able to target tumors through the interaction between folic acid and its receptors which are overexpressed on the tumor cell membrane, and achieved pH-dependent thermo induced drug release in the intracellular mild acidic media such as endosomes and lysosomes after the micelles enter the cells. The results of cell assays and animal experiments showed that the micelles exhibited obvious tumor penetration efficiency in vivo, also improved DOX cell uptake and cytotoxicity in vitro. It was suggested that copolymer PLA-PNNUA-FA might be a potential targeted drug carrier to deliver chemotherapeutic drugs achieving better efficacy of chemotherapy.