Targeting Of Liposomes Research Articles

Dual-functional liposome for tumor targeting and overcoming multidrug resistance in hepatocellular carcinoma cells

The purpose of this study was to design and evaluate the dual-functional liposome (LPG) with synthetic polymeric nano-biomaterial (Gal-P123) that targets cancer cells and reverses multidrug resistance (MDR) in hepatocellular carcinoma (HCC) cells. The mitoxantrone (MX) loaded LPG (MX-LPG) was about 100 nm in diameter, spherically shaped, and had an encapsulation efficiency of 97.3%. The cytotoxicity and cellular uptake of MX-LPG were evaluated in HCC Huh-7 cells. BCRP-overexpressing MDCKII/BCRP cells were used to certify the inhibitory effect of LPG on drug efflux transporter. Compared with MX, MX-LPG had 2.3-fold higher cytotoxicity in Huh-7 cells and a 14.9-fold increase in cellular MX accumulation in MDCKII/BCRP cells. The pharmacokinetic study in rats showed that LPG significantly prolonged the circulation time and enhanced the bioavailability of MX. Moreover, MX-LPG increased antitumor activity and improved selectivity in BALB/c mice bearing orthotopic xenograft HCC tumors.

Synthesis of Multivalent Glucosides with High Affinity for GLUT1 Transporter

The novel bifunctional compounds L1 and L2 carrying cluster glucosides as ligands for brain targeting liposomes were synthesized. 2-phenyl-1,3-dioxan-5-ol (8) and tetra-antennary alcohol (13) were used as the core scaffold to attach cholesterol derivatives by a triethylene glycol chain, while their remaining branches were linked with two or three benzylglucosides, which would be debenzvlated later to produce di-antennary glucosides L1 and tri-antennary glucosides ligand L2. This design provided an effective entry for the synthesized bifunctional compounds to cross blood brain barrier (BBB).

Erratum: Development of a successive targeting liposome with multi‐ligand for efficient targeting gene delivery

<i>Erratum</i>: Development of a successive targeting liposome with multi‐ligand for efficient targeting gene delivery

Abstract 1961: Evaluated mechanism of dual targeting using liposomal doxorubicin-modified novel PEG by imaging analysis

Abstract [Purpose] Liposome is one of the useful drug carriers and it may be applying to a lot of diseases from now on. One of the most reasons which liposomes were using as medicine was improvement of circulation time in bloodstream by modifying polyethyleneglycol (PEG)-lipid. We synthesized novel PEG-lipid with two different PEG lengths of 2000 and 500 (different double arms-PEG; DDA-PEG) for developing more superior passive targeting liposome. In our previous study, doxorubicin (DOX) containing liposome which was modified DDA-PEG (DDA-PEG modified liposomal DOX; DDA-LDOX) had dual effect for primary and hepatic metastasis cancer. In this study, we observed tissue distribution at primary tumor using the near infrared fluorescence and analyzed hepatic metastasis by histological observation for explain this dual effect. Moreover, this effect for pulmonary metastasis was also evaluated. [Methods] Liposome (DSPC/cholesterol/DSPG-Na/DDA-PEG = 100:100:60:7.5 μmol) was prepared according to the method of Bangham. For observing tissue distribution of liposome at primary tumor model, liposome was contained indocyanine green (ICG) as fluorescence probe. This liposome was injected in tail vein and sequentially observed using fluorescent imaging device (Clairvivo OPT, SHIMADZU). In histological observation at hepatic metastasis murine model, M5076 ovarian sarcoma cells were inoculated in tail vein of mice. These mice were injected liposome at a dose of 2.5 mg/kg (i.v.) as DOX on 6, 9 and 12 d after tumor inoculation. At 14 d, this liver was removed and examined by microscope after HE stain. At assessment of pulmonary metastasis, B16F10 melanoma cells were implanted in tail vein and treated similarly to liver metastasis.[Results and discussion] In fluorescent imaging of primary tumor, DDA-PEG modified liposome assembled into tumor at 48 h after injection. This analysis supported our previous finding that DDA-LDOX significantly decreased tumor size. Furthermore, it was proved that DDA-PEG modified liposome or encapsulated drug remained in tumor site for a long time. In histological examination for hepatic metastasis, the tumor area in the liver was 5% by DDA-LDOX injection (normal group: 90%). More lymphocytes around tumor thrombus were positive for CD45. It was suggested that macrophage or lymphocytes, especially T cell, were concerned in this therapy. Pulmonary metastasis was depressed by DDA-LDOX compared with control or DOX containing PEG unmodified liposome group. In DDA-LDOX group, DOX concentration in lung was 2.6 times higher than that in PEG unmodified liposome group. It is known that metastasis is the most severe factor in cancer chemotherapy. Antitumor agent containing DDA-PEG modified liposome may have not only superior effect for primary tumor but also hepatic or pulmonary metastasis. Hence, it was suggested that DDA-PEG modified liposome was useful drug carrier for passive targeting. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 1961. doi:1538-7445.AM2012-1961

Liposomes for Cardiovascular Targeting

Liposome-based pharmaceuticals used within the cardiovascular system are reviewed in this article. The delivery of diagnostic and therapeutic agents by plain liposomes and liposomes with surface-attached targeting antibodies or polyethylene glycol to prolong their circulation time and accumulation at vascular injuries, ischemic zones or sites of thrombi are also discussed. An overview of the advantages and disadvantages of liposome-mediated in vitro, ex vivo and in vivo targeting is presented, including discussion of the targeting of liposomes to pathological sites on the blood vessel wall and a description of liposomes that can be internalized by endothelial cells. Diagnostic liposomes used to target myocardial infarction and the relative importance of liposome size, targetability of immunoliposomes and prolonged circulation time on the efficiency of sealing hypoxia-induced plasma membrane damage to cardiocytes are discussed as a promising approach for therapy. The progress in the use of targeted liposomal plasmids for the transfection of hypoxic cardiomyocytes and myocardium is presented. Stent-mediated liposomal-based drug delivery is also reviewed briefly.

Analysis of gemcitabine liposome injection by HPLC with evaporative light scattering detection

Gemcitabine liposome injection (i.e., stealth liposomes) has facilitated the targeting of gemcitabine for cancer treatment. We systemically reviewed liposome-based drug-delivery systems, which can improve pharmacokinetics, reduce side effects, and potentially increase tumor uptake, for pancreatic cancer therapy. A novel liposomal formulation, which allows for higher tumor-targeting efficiencies and can be used in current clinical trials to treat this challenging disease, has gained great popularity and attention. In this work, a simple, rapid high-performance liquid chromatography (HPLC) method was developed for the simultaneous determination of N-(carbonyl-methoxypolyethylene glycol 2000)-1, 2-distearoyl-sn-glycero-3-phosphoethanolamine sodium salt and neutral colipids cholesterol and hydrogenated soy phosphatidylcholine or distearoyl phosphatidylcholine. Because of the poor ultraviolet absorbance of the lipids, evaporative light-scattering detection (ELSD) was used to monitor the separation. The separation was carried out on a YMC-Pack column (YMC Co., Ltd., Kyoto, Japan). Lipids were eluted using binary linear gradients starting from a mixture of 80% A and 20% B to 100% B in 10 minutes, followed by a 6-minute plateau at 100% B, where A is chloroform/isopropyl alcohol/diethylamine/trifluoroacetic acid (TFA) (50:50:0.01:0.0025) and B is chloroform/isopropyl alcohol/H2O/diethylamine/TFA (41:50:9:0.01:0.0025). The mobile phase composition was then changed back to initial solvent mixture in 1 minute, and the column was equilibrated for 13 minutes before every subsequent run. Then, 0.025% (v/v) TFA was added into the mobile phase to enhance the retaining of the stealth lipids. This newly developed method enabled direct analysis of liposomes without solvent lipid extraction and was validated to be linear, precise, accurate, specific, and sensitive. The method has been successfully employed in a wide range of lipid-based formulation screening, process development, and stability testing. Further, we describe the simple, rapid HPLC-ELSD method for the simultaneous determination of all the lipids and active pharmaceutical ingredients in various liposome-based drug formulations. The method can quantitate all the lipids of active targeting liposomes, which bond with folic acid.

Challenges in Development of Targeted Liposomal Therapeutics

Liposomes, phospholipid vesicles with a bilayered membrane structure, have been widely used as pharmaceutical carriers for drugs and genes, in particular for treatment of cancer. To enhance the efficacy of the liposomal drugs, drug-loaded liposomes are targeted to the tumors by means of passive (enhanced permeability and retention mediated) targeting, based on the longevity of liposomes in blood and its accumulation in pathological sites with compromised vasculature, and active targeting, based on the attachment of specific ligands to the liposomal surface to bind certain antigens on the target cells. Antibody-targeted liposomes loaded with anticancer drugs demonstrate high potential for clinical applications. This review highlights evolution of liposomes for both passive and active targeting and challenges in development of targeted liposomal therapeutics specifically antibody-targeted liposomes.

Design of cyclic RKKH peptide-conjugated PEG liposomes targeting the integrin α2β1 receptor

Peptide conjugation to the surface of stealth liposomes has been studied for liposomal drug targeting to cells expressing specific receptors to provide a site-specific drug delivery. This study investigated the potential of peptide-conjugated liposomes for targeting cells expressing the human integrin α2β1 receptor. A 12 amino acid head-to-tail cyclic peptide derived from the Jararhagin protein containing the Arg-Lys-Lys-His (RKKH)-specific binding site was conjugated to the distal ends of poly(ethylene glycol) (PEG) chains on PEGylated liposomes. Epithelial cells expressing the receptor showed increased cellular association and uptake of peptide-conjugated liposomes at 4°C, compared to liposomes conjugated with a non-specific peptide. The interaction between cells and peptide-conjugated liposomes was significantly increased at 37°C suggesting that a possible uptake mechanism might be energy-dependent endocytosis. In keratinocyte cell cultures, the ligand-conjugated liposomes loaded with the vitamin D3 analogue calcipotriol induced transcription of the gene encoding the antimicrobial peptide cathelicidin, which is activated through the vitamin D3 receptor upon binding of vitamin D3 analogues. This suggests that the liposomes are internalized and that calcipotriol is delivered intracellularly and released in an active form. In conclusion, the 12 amino acid head-to-tail cyclic RKKH peptide seems promising for targeting of liposomes to the integrin α2β1 receptor.

Theranostic liposomes of TPGS coating for targeted co-delivery of docetaxel and quantum dots

The aim of this work was to develop a new type of d-alpha-tocopheryl polyethylene glycol 1000 succinate mono-ester (TPGS) coated multi-functional (theranostic) liposomes, which contain both docetaxel and quantum dots (QDs) for cancer imaging and therapy. Non-targeting and folate receptor targeting TPGS coated theranostic liposomes were prepared by the solvent injection method and characterized for their particle size, polydispersity, zeta potential, surface chemistry and drug encapsulation efficiency. MCF-7 breast cancer cells of folate receptor overexpression were employed as an in vitro model to assess cellular uptake and cytotoxicity of the drug and QDs loaded liposomes. The mean particle size of the non-targeting and the targeting liposomes was found to be 202 and 210 nm, respectively. High resolution field emission transmission electron microscopy (FETEM) confirmed the presence of quantum dots in the peripheral hydrophobic membranes of the liposomes. The qualitative internalization of multi-functional liposomes by MCF-7 cells was visualized by confocal laser scanning microscopy (CLSM). The IC50 value, which is the drug concentration needed to kill 50% cells in a designated time period, was found to be 9.54 ± 0.76, 1.56 ± 0.19 and 0.23 ± 0.05 μg/ml for the commercial Taxotere®, non-targeting and targeting liposomes, respectively after 24 h culture with MCF-7 cells. The targeting multi-functional liposomes showed greater efficacy than the non-targeting liposomes and thus great potential to improve the cancer imaging and therapy.

Efficient intracellular drug-targeting of macrophages using stealth liposomes directed to the hemoglobin scavenger receptor CD163

The hemoglobin scavenger receptor CD163 is exclusively expressed in the monocytic lineage and preferentially in tissue resident macrophages of the M2 phenotype and in macrophages in sites of inflammation and tumor growth. In the present study we have designed liposomes specifically targeting CD163 by hydrophobic linkage of CD163-binding monoclonal antibodies to polyethylene glycol-coated liposomes (‘stealth liposomes’). Targeting to the endocytic CD163 protein greatly increased the uptake of liposomes in CD163 transfected cells and macrophages as visualized by confocal microscopy and flow cytometry of cells exposed to CD163 targeting liposomes loaded with calcein. Strong cytotoxic effects were seen in CD163-expressing human monocytes by using the chemotherapeutic agent doxorubicin as cargo of the liposomes.In conclusion, the use of stealth liposomes modified to recognize CD163 is a potential way to target drugs to macrophages that support inflammatory and malignant processes.

Design, Construction, and Characterization of High-Performance Membrane Fusion Devices with Target-Selectivity

Membrane fusion proteins such as the hemagglutinin glycoprotein have target recognition and fusion accelerative domains, where some synergistically working elements are essential for target-selective and highly effective native membrane fusion systems. In this work, novel membrane fusion devices bearing such domains were designed and constructed. We selected a phenylboronic acid derivative as a recognition domain for a sugar-like target and a transmembrane-peptide (Leu-Ala sequence) domain interacting with the target membrane, forming a stable hydrophobic α-helix and accelerating the fusion process. Artificial membrane fusion behavior between the synthetic devices in which pilot and target liposomes were incorporated was characterized by lipid-mixing and inner-leaflet lipid-mixing assays. Consequently, the devices bearing both the recognition and transmembrane domains brought about a remarkable increase in the initial rate for the membrane fusion compared with the devices containing the recognition domain alone. In addition, a weakly acidic pH-responsive device was also constructed by replacing three Leu residues in the transmembrane-peptide domain by Glu residues. The presence of Glu residues made the acidic pH-dependent hydrophobic α-helix formation possible as expected. The target-selective liposome-liposome fusion was accelerated in a weakly acidic pH range when the Glu-substituted device was incorporated in pilot liposomes. The use of this pH-responsive device seems to be a potential strategy for novel applications in a liposome-based delivery system.

Peptide-mediated targeting of liposomes to TrkB receptor-expressing cells

BackgroundThe neurotrophic receptor tyrosine kinase B (TrkB) has diverse signaling roles in neurons and tumor cells. Accordingly, its suppressive targeting is of interest in neuroblastoma and other tumors, whereas its role in improving survival is focused in neurons. Here we describe targeting of TrkB-binding peptide-conjugated liposomes (PCL) to the TrkB-expressing mouse macrophage-like cell line RAW264, and to all-trans-retinoic acid-treated neuron-like TrkB+ SH-SY5Y human neuroblastoma cells.MethodsBinding and internalization of PCL was monitored by flow cytometry and confocal fluorescence microscopy.ResultsInternalization of TrkB-targeted PCL by RAW264 cells was enhanced and faster when compared with PCL having the corresponding scrambled peptide. Likewise, binding and augmented uptake were confirmed for TrkB+ SH-SY5Y cells, with targeted PCL appearing in the cytoplasm after 20 minutes of incubation.ConclusionWe demonstrate here the feasibility of targeting liposomes to TrkB-expressing cells by 18-mer peptides, promoting cellular uptake (at least partly into endosomes) via receptor-mediated pathways.

Ultrasmall superparamagnetic iron oxide (USPIO)-based liposomes as magnetic resonance imaging probes

BackgroundMagnetic liposomes (MLs) are phospholipid vesicles that encapsulate magnetic and/or paramagnetic nanoparticles. They are applied as contrast agents for magnetic resonance imaging (MRI). MLs have an advantage over free magnetic nanocores, in that various functional groups can be attached to the surface of liposomes for ligand-specific targeting. We have synthesized PEG-coated sterically-stabilized magnetic liposomes (sMLs) containing ultrasmall superparamagnetic iron oxides (USPIOs) with the aim of generating stable liposomal carriers equipped with a high payload of USPIOs for enhanced MRI contrast.MethodsRegarding iron oxide nanoparticles, we have applied two different commercially available surface-coated USPIOs; sMLs synthesized and loaded with USPIOs were compared in terms of magnetization and colloidal stability. The average diameter size, morphology, phospholipid membrane fluidity, and the iron content of the sMLs were determined by dynamic light scattering (DLS), transmission electron microscopy (TEM), fluorescence polarization, and absorption spectroscopy, respectively. A colorimetric assay using potassium thiocyanate (KSCN) was performed to evaluate the encapsulation efficiency (EE%) to express the amount of iron enclosed into a liposome. Subsequently, MRI measurements were carried out in vitro in agarose gel phantoms to evaluate the signal enhancement on T1- and T2-weighted sequences of sMLs. To monitor the biodistribution and the clearance of the particles over time in vivo, sMLs were injected in wild type mice.ResultsDLS revealed a mean particle diameter of sMLs in the range between 100 and 200 nm, as confirmed by TEM. An effective iron oxide loading was achieved just for one type of USPIO, with an EE% between 74% and 92%, depending on the initial Fe concentration (being higher for lower amounts of Fe). MRI measurements demonstrated the applicability of these nanostructures as MRI probes.ConclusionOur results show that the development of sMLs is strictly dependent on the physicochemical characteristics of the nanocores. Once established, sMLs can be further modified to enable noninvasive targeted molecular imaging.

Peptide-modified liposomes for selective targeting of bombesin receptors overexpressed by cancer cells: a potential theranostic agent

ObjectivesDrug delivery systems consisting of liposomes displaying a cell surface receptor-targeting peptide are being developed to specifically deliver chemotherapeutic drugs to tumors overexpressing a target receptor. This study addresses novel liposome composition approaches to specifically target tissues overexpressing bombesin (BN) receptors.MethodsA new amphiphilic peptide derivative (MonY-BN) containing the BN(7–14) peptide, the DTPA (diethylenetriaminepentaacetate) chelating agent, a hydrophobic moiety with two C18 alkyl chains, and polyethylene glycol spacers, has been synthesized by solid-phase methods. Liposomes have been generated by co-aggregation of MonY-BN with 1,2-distearoyl-sn-glycero-3-phosphocholine (DSPC). The structural and biological properties of these new target-selective drug-delivery systems have been characterized.ResultsLiposomes with a DSPC/MonY-BN (97/3 molar ratio) composition showed a diameter of 145.5 ± 31.5 nm and a polydispersity index of 0.20 ± 0.05. High doxorubicin (Dox) loading was obtained with the remote pH gradient method using citrate as the inner buffer. Specific binding to PC-3 cells of DSPC/MonY-BN liposomes was obtained (2.7% ± 0.3%, at 37°C), compared with peptide-free DSPC liposomes (1.4% ± 0.2% at 37°C). Incubation of cells with DSPC/ MonY-BN/Dox showed significantly lower cell survival compared with DSPC/Dox-treated cells, in the presence of 100 ng/mL and 300 ng/mL drug amounts, in cytotoxicity experiments. Intravenous treatment of PC-3 xenograft-bearing mice with DSPC/MonY-BN/Dox at 10 mg/kg Dox dose produced higher tumour growth inhibition (60%) compared with nonspecific DSPC/ Dox liposomes (36%) relative to control animals.ConclusionThe structural and loading properties of DSPC/MonY-BN liposomes along with the observed in-vitro and in-vivo activity are encouraging for further development of this approach for target-specific cancer chemotherapy.

Ovarian Tumor Targeting of Docetaxel-Loaded Liposomes Mediated by Luteinizing Hormone-Releasing Hormone Analogues

Recent studies indicate that luteinizing hormone-releasing hormone (LHRH) analogues (LHRHa), like LHRH, are able to specifically bind to LHRH receptors which are highly expressed on the extracellular membrane of ovarian tumor cells. As a targeting moiety, LHRHa can mediate the ovarian tumor targeting of docetaxel-loaded liposomes. In our study, synthesized negatively charged cholesterol succinimide (CHS) was employed for the preparation of negatively charged docetaxel-loaded liposomes, with which the positively charged LHRHa is linked via electrostatic absorption. An HPLC-based assay for determination of docetaxel (CAS 114977-28-5, Doc) in vivo and the model of ovarian cancer xenograft were established to investigat the biodistribution of docetaxel, docetaxel liposomes (Doc-Lipo), and LHRHa mediated docetaxel-loaded liposomes (LHRHa-Doc-Lipo) in nude mice. Sixty minutes after administration of LHRHa-Doc-Lipo, the concentration of docetaxel in the ovarian tumor was 2.86 times that of Doc-Lipo and 9.02 times that of Doc in the nude mice bearing ovarian tumor. LHRHa-Doc-Lipo decreased the concentration of docetaxel in the liver and spleen by 57% and 34%, respectively, as compared with Doc-Lipo. Therefore, LHRHa-Doc-Lipo exhibits potentiality as an active targeting drug delivery system for chemotherapy of ovarian tumor.

Mitochondrial targeting topotecan-loaded liposomes for treating drug-resistant breast cancer and inhibiting invasive metastases of melanoma

Multidrug resistance and cancer metastases are two obstacles to a successful chemotherapy and metastases are closely associated with drug resistance. Mitochondrial targeting topotecan-loaded liposomes have been developed to overcome this resistance and resistance-related metastases. Investigations were performed on breast cancer MCF-7 and resistant MCF-7/adr cells, MCF-7 and resistant MCF-7/adr tumor spheroids, resistant MCF-7/adr cell xenografts in nude mice, and a naturally resistant B16 melanoma metastatic model in nude mice. The mitochondrial targeting topotecan-loaded liposomes were approximately 64 nm in size, and exhibited the strongest inhibitory effects on MCF-7 cells and resistant MCF-7/adr cells. Mitochondrial targeting effects were demonstrated by co-localization in mitochondria, enhanced drug content in mitochondria, dissipated mitochondrial membrane potential, opening of mitochondrial permeability transition pores, release of cytochrome C, and activation of caspase 9 and 3. The targeting liposomes had a stronger inhibitory effect on the resistant tumor spheroids in vitro, enhanced accumulation in resistant MCF-7/adr cell xenografts in mice, as well as being very effective on resistant MCF-7/adr cell xenografts in mice, and having a marked anti-metastastic effect on the naturally resistant B16 melanoma metastatic model in mice. In conclusion, mitochondrial targeting topotecan-loaded liposomes could be a promising strategy for treating resistant cancers and resistance-related metastases.

Estrogen-Anchored pH-Sensitive Liposomes as Nanomodule Designed for Site-Specific Delivery of Doxorubicin in Breast Cancer Therapy

The present investigation reports the development of nanoengineered estrogen receptor (ER) targeted pH-sensitive liposome for the site-specific intracellular delivery of doxorubicin (DOX) for breast cancer therapy. Estrone, a bioligand, was anchored on the surface of pH-sensitive liposome for drug targeting to ERs. The estrone-anchored pH-sensitive liposomes (ES-pH-sensitive-SL) showed fusogenic potential at acidic pH (5.5). In vitro cytotoxicity studies carried out on ER-positive MCF-7 breast carcinoma cells revealed that ES-pH-sensitive-SL formulation was more cytotoxic than non-pH-sensitive targeted liposomes (ES-SL). The flow cytometry analysis confirmed significant enhanced uptake (p < 0.05) of ES-pH-sensitive-SL by MCF-7 cells. Intracellular delivery and nuclear localization of the DOX was confirmed by fluorescence microscopy. The mechanism for higher cytotoxicity shown by estrone-anchored pH-sensitive liposomal-DOX was elucidated using reactive oxygen species (ROS) determination. The in vivo biodistribution studies and antitumor activities of formulations were evaluated on tumor bearing female Balb/c mice followed by intravenous administration. The ES-pH-sensitive-SL efficiently suppressed the breast tumor growth in comparison to both ES-SL and free DOX. Serum enzyme activities such as LDH and CPK levels were assayed for the evaluation of DOX induced cardiotoxicity. The ES-pH-sensitive-SL accelerated the intracellular trafficking of encapsulated DOX, thus increasing the therapeutic efficacy. The findings support that estrone-anchored pH-sensitive liposomes could be one of the promising nanocarriers for the targeted intracellular delivery of anticancer agents to breast cancer with reduced systemic side effects.

Critical factors in the development of tumor-targeted anti-inflammatory nanomedicines

Tumors are complex and dynamic assemblies of different cell types within an atypical/abnormal architecture. Tumor-associated macrophages, mast cells, dendritic cells, eosinophils, fibroblasts are present in and around tumors and contribute to an abundant, deregulated and long lasting chronic inflammation, a permissive microenvironment for tumor proliferation. The fact that tumor-initiated inflammation overrides protective immunity and supports tumor development, combined with the successful strategy of liposomal drug targeting to tumor tissues, gave rise to a novel attractive antitumor therapeutic strategy: targeting anti-inflammatory drugs to tumors.As many natural bioactive compounds have anti-inflammatory properties and act by targeting multiple signaling pathways, their medicinal application involves the treatment of cancer. The nanoformulation into liposomes circumvents solubility, stability, bioavailability issues associated with these compounds, while promoting tumor drug accumulation.Liposomal formulations of resveratrol, carvacrol phosphate, pterostilbene phosphate, N-(3-oxo-dodecanoyl)-l-Homoserine lactone, caffeic acid and caffeic acid phenethyl ester (CAPE) were prepared and characterized. In vivo, B16F10 melanoma bearing mice seem not to be responsive to liposomal treatments of natural compounds. The specific combination of tumor model, drug delivery system and drug potency are crucial factors that should be considered in the development and evaluation of new nanomedicines for cancer-inflammation therapy, especially when translating from preclinical models.

RGD-based active targeting of novel polycation liposomes bearing siRNA for cancer treatment

For the purpose of systemic delivery of siRNA, we previously developed polycation liposomes (PCLs) containing dicetylphosphate-tetraethylenepentamine (DCP-TEPA) as an effective siRNA carrier. In the present study, to endow these PCLs (TEPA-PCL) actively target cancer cells and angiogenic vessels, we decorated the PCLs with cyclic RGD, by using cyclic RGD-grafted distearoylphosphatidylethanolamine-polyethylene glycol (DSPE-PEG), and investigated the usefulness of this type of carrier (RGD-PEG-PCL) for active targeting. Firstly, the gene-silencing efficacy of siRNA for luciferase (siLuc2) formulated in RGD-PEG-PCL (RGD-PEG-PCL/siLuc2) was examined in vitro by using B16F10-luc2 murine melanoma cells stably expressing the luciferase 2 gene, where the siRNA was grafted with cholesterol at the 3′-end of the sense strand (siRNA-C) for the stable association of the siRNA with the PCL. RGD-PEG-PCL/siLuc2 showed high knockdown efficiency compared with siLuc2 formulated in PEGylated TEPA-PCL without cyclic RGD (PEG-PCL). Next, the gene-silencing efficacy of RGD-PEG-PCL/siLuc2 was examined in vivo by use of B16F10-luc2 lung metastatic model mice. The intravenous injection of RGD-PEG-PCL/siLuc2 showed high knockdown efficiency against metastatic B16F10-luc2 tumors in the lungs of the mice, as assessed with an in vivo imaging system. These data strongly suggest that systemic and active targeting siRNA delivery using RGD-PEG-PCL is useful for cancer RNAi therapy.

Mitochondrial targeting liposomes incorporating daunorubicin and quinacrine for treatment of relapsed breast cancer arising from cancer stem cells

Breast cancer stem cells play a crucial role in the relapse of breast cancers because they are resistant to a standard chemotherapy and the residual cancer stem cells are able to proliferate indefinitely. The objectives of present study were to construct a kind of mitochondrial targeting daunorubicin plus quinacrine liposomes for treating and for preventing the recurrence of breast cancer arising from the cancer stem cells. MCF-7 cancer stem cells were identified as CD44 +/CD24 − cells and cultured in free-serum medium. Evaluations were performed on MCF-7 cancer stem cells, MCF-7 cancer stem cell mammospheres, and the relapsed tumor by xenografting MCF-7 cancer stem cells into female NOD/SCID mice. The particle size of mitochondrial targeting daunorubicin plus quinacrine liposomes was approximately 98 nm. The mitochondrial targeting liposomes evidently increased the mitochondrial uptake of drugs, were selectively accumulated into mitochondria, activated the pro-apoptotic Bax protein, dissipated the mitochondrial membrane potential, opened the mitochondrial permeability transition pores, released cytochrome C by translocation, and initiated a cascade of caspase 9 and 3 reactions, thereby inducing apoptosis of MCF-7 cancer stem cells. The mitochondrial targeting liposomes showed the strongest efficacy in treating MCF-7 cancer cells in vitro, in treating MCF-7 cancer stem cells in vitro, and in treating the relapsed tumor in mice. Mitochondrial targeting daunorubicin plus quinacrine liposomes would provide a new strategy for treating and preventing the relapse of breast cancers arising from cancer stem cells.