A doxorubicin-CNGRC-peptide conjugate with prodrug properties

There is increasing interest in the exploitation of molecular addresses for the targeting of tumor imaging or therapeutic agents. A recent study demonstrated anticancer activity in human xenografts of doxorubicin (DOX)-peptide conjugates targeted to the tumor vascular endothelium, among them DOX coupled to the cyclic pentapeptide CNGRC [Science 279 (1998) 377]. In order to learn more about the mechanism of action of this type of DOX-peptide conjugates, we have studied the interaction of DOX-CNGRC with primary human umbilical cord vein endothelial cells (HUVEC) and tumor cells under defined in vitro conditions. We used a DOX conjugate, in which the cyclic CNGRC peptide, for which an in vivo endothelial address has recently been identified as aminopeptidase N (APN)/CD13, has been coupled via a hydrolysable spacer to the C-14 anthracycline-side chain. First we determined that the t(1/2) of DOX-CNGRC conjugate in human blood was 442 min (at 37 degrees ) allowing sufficient time for endothelial targeting when administered i.v. When cultured cells were exposed for 30 min to DOX-CNGRC a more cytoplasmic localization of fluorescent drug was seen when compared to DOX exposure and intracellular DOX-CNGRC was identified after extraction from the cells. This revealed differences in the cellular uptake process of the conjugate compared to DOX. The antiproliferative effect of DOX-CNGRC was determined by 30 min exposure in medium with a high protein content in order to mimick the in vivo targeting situation. In this medium, the IC(50) was 1.1 microM for highly CD13 expressing HT-1080, 1.45 microM for CD13 negative SK-UT-1 sarcoma cells and 6.5 microM for CD13 positive HUVEC. The IC(50) of DOX for these cells were 1.0, 2.0 and 7.3 microM, respectively. Although DOX-CNGRC inhibited the peptidase activity of CD13 up to 50%, our data do not favor an important role for the enzyme inhibition in the cytotoxic effect of the conjugate. The antitumor activity was tested in nude mice bearing human ovarian cancer xenografts (OVCAR-3). A weekly i.v. administration (3mg/kg DOX-equivalent, 3x) showed a minor (40%) growth delay, which does not indicate efficacy better than that expected for free DOX. In conclusion, this study indicates that the antiproliferative and anti-angiogenic effects of DOX-CNGRC as reported before, are likely caused by the cytostatic effects of intracellularly released parent drug DOX, independent of CD13 expression/activity. More research is needed to identify the optimal specific chemical configuration of DOX-peptide conjugates for in vivo targeting and receptor-mediated cellular uptake.     

A preliminary study on the interaction between Asn-Gly-Arg (NGR)-modified multifunctional nanoparticles and vascular epithelial cells

Previously developed Asn-Gly-Arg (NGR) peptide-modified multifunctional poly(ethyleneimine)–poly(ethylene glycol) (PEI–PEG)-based nanoparticles (TPIC) have been considered to be promising carriers for the co-delivery of DNA and doxorubicin (DOX). As a continued effort, the aim of the present study was to further evaluate the interaction between TPIC and human umbilical vein endothelial cells (HUVEC) to better understand the cellular entry mechanism. In the present investigation, experiments relevant to co-localization, endocytosis inhibitors and factors influencing the internalization were performed. Without any treatment, there was no co-localization between aminopeptidase N/CD13 (APN/CD13) and caveolin 1 (CAV1). However, co-localization between CD13 and CAV1 was observed when cells were incubated with an anti-CD13 antibody or TPIC. As compared with antibody treatment, TPIC accelerated the speed and enhanced the degree of co-localization. TPIC entered HUVEC not only together with CD13 but also together with CAV1. However, this internalization was not dependent on the enzyme activity of CD13 but could be inhibited by methyl-β-eyclodextfin (MβCD), further identifying the involvement of caveolae-mediated endocytosis (CvME). This conclusion was also verified by endocytosis inhibitor experiments.     

Vascular targeting of doxorubicin using cationic liposomes

Tumor vessel has been recognized as an important target for anticancer therapy. Cationic liposomes have been shown to selectively target tumor endothelial cells, thus can potentially be used as a carrier for chemotherapy agents. In this study, cationic liposomes containing 20 mol% cationic lipid dimethyl dioctadecyl ammonium bromide (DDAB) and loaded with doxorubicin (DOX) were prepared and characterized. The cationic liposomal DOX showed 10.8 and 9.1 times greater cytotoxicity than control PEGylated liposomal DOX in KB oral carcinoma and L1210 murine lymphocytic leukemia cells, and 7.7- and 6.8-fold greater cytotoxicity compared to control neutral non-PEGylated liposomal DOX, repectively, in these two cell lines. Although cationic liposomal DOX had higher tumor accumulation at 30 min after intravenous administration compared to control liposomes (p<0.05), DOX uptake of these liposomes at 24h post-injection was similar to that of PEGylated liposomal DOX (p>0.05) and approximately twice the levels of the free drug and non-PEGylated liposomes. In a murine tumor model generated using L1210 cells, increased survival rate was obtained with cationic liposomal DOX treatment compared to free DOX (p<0.01), neutral liposome control (p<0.01), as well as PEGylated liposomes (p<0.05). In conclusion, the cationic liposomal DOX formulation produced superior in vitro cytotoxicity and in vivo antitumor activity, and warrants further investigation.     

Novel tetrapeptide, RGDF, mediated tumor specific liposomal doxorubicin (DOX) preparations

Arginine-glycine-aspartate (RGD) has been shown to possess a strong affinity for the integrins overexpressed in tumor cells, especially during tumor invasion, angiogenesis and metasis. Based on work from others, a novel tetrapeptide, arginine-glycine-aspartate-phenylanaline (RGDF), has been designed and studied as a homing device to direct liposomal doxorubicin (DOX) to tumor cells in this work. In order to incorporate RGDF into liposomal DOX preparations, RGDF was conjugated with three different fatty alcohols to achieve RGDF-fatty alcohol conjugates. Glycine-glycine-aspartate-phenylanaline (GGDF)-lauryl alcohol conjugate was synthesized as a negative control. RGDF-fatty alcohol conjugates (RGDFO(CH(2))(n)CH(3)) and GGDF-lauryl alcohol conjugate (L-GGDFC12-DOX) incorporated liposomal preparations were obtained by first preparing liposomes using the film dispersion method followed by loading DOX using a transmembrane pH gradient method. Because of their amphipathic nature, RGDF- or GGDF-fatty alcohol conjugates are expected to be readily incorporated into liposomes with their fatty alkanyl chains being intercalated between fatty acyl chains of liposomal bilayers and the hydrophilic peptide moiety (RGDF or GGDF) being anchored on the surface of liposomes. The particle size and zeta potential of liposomal DOX preparations containing RGDF-fatty alcohol conjugate (L-RGDF-DOXs) or L-GGDFC12-DOX were measured, and their morphology was studied using transmission electron microscopy. In vitro DOX release profile from RGDF incorporated liposomal DOX was measured. The antitumor activities of RGDF incorporated liposomal DOX preparations were evaluated in ICR mice inoculated with sarcoma S(180), which is known to express α(v)β(3) integrin. Both conventional liposomal DOX preparation (L-DOX) without RGDFO(CH(2))(n)CH(3) and L-GGDFC12-DOX were used as negative controls. Our results showed improved tumor growth inhibition with L-RGDF-DOXs over doxorubicin hydrochloride solution, L-DOX and L-GGDFC12-DOX. Pathological examination of tumor biopsy demonstrated that L-RGDF-DOXs induced enhanced tumor cell death in comparison to negative controls. Pharmacokinetic studies showed that the concentrations of DOX found in tumor sites were increased by 1.7-4.5-fold when liposomal DOX preparation containing RGDF-lauryl alcohol conjugate (L-RGDFC12-DOX) was administered in comparison to when L-GGDFC12-DOX or doxorubicin hydrochloride solution was administered. The concentrations of DOX found in the heart, which is the main site of toxic effects of DOX, were significantly reduced when L-RGDFC12-DOX was administered in comparison to when L-GGDFC12-DOX or doxorubicin hydrochloride solution was administered.     

Anti-tumor targeted drug delivery systems mediated by aminopeptidase N/CD13

Aminopeptidase N (APN)/CD13 is a transmembrane glycoprotein, which is overexpressed on tumor neovascular endothelial cells and most tumor cells, where it plays an important role in tumor angiogenesis. Peptides containing the Asn-Gly-Arg (NGR) motif can specifically recognize APN/CD13 allowing them to act as tumor-homing peptides for the targeted delivery of anti-tumor drugs to tumor neovascular endothelial cells and tumor cells. This article reviews the literature and recent developments related to APN/CD13, its role in tumor growth and some anti-tumor drug delivery systems containing NGR peptides designed to target APN/CD13.     

Single-walled carbon nanotube-loaded doxorubicin and Gd-DTPA for targeted drug delivery and magnetic resonance imaging

An aspargine-glycine-arginine (NGR) peptide modified single-walled carbon nanotubes (SWCNTs) system, developed by a simple non-covalent approach, could be loaded with the anticancer drug doxorubicin (DOX) and magnetic resonance imaging (MRI) contrast agent gadolinium-diethylenetriamine pentaacetic acid (Gd-DTPA). This DOX- and Gd-DTPA-loaded NGR functionalized SWCNTs (DOX/NGR-SWCNTs/Gd-DPTA) retained both cytotoxicity of DOX and MRI contrast effect of Gd-DPTA. This drug delivery system showed excellent stability in physiological solutions. This DOX/NGR-SWCNTs/Gd-DPTA system could accumulate in tumors and enter into tumor cells, which facilitated combination chemotherapy with diagnosis of tumor in one system. An excellent in vitro anti-tumor effect was shown in MCF-7 cells treated by DOX/NGR-SWCNTs/Gd-DPTA, compared with DOX solution, DOX/SWCNTs and DOX/SWCNTs/Gd-DPTA. In vivo data of DOX/NGR-SWCNTs/Gd-DPTA group in tumor-bearing mice further confirmed that this system performed much higher tumor targeting capacity and anti-tumor efficacy than other control groups.     

A photo-responsive peptide- and asparagine–glycine–arginine (NGR) peptide-mediated liposomal delivery system

The conjugation of tunable peptides or materials with nanocarriers represents a promising approach for drug delivery to tumor cells. In this study, we report the development of a novel liposomal carrier system that exploits the cell surface binding synergism between photo-sensitive peptides (PSPs) and targeting ligands. The positive charges of the lysine residues on the cell-penetrating peptides (CPPs) were temporarily caged by the photolabile-protective groups (PG), thereby forming a PSP. Furthermore, this PSP enhances specific uptake into cancer cells after rapidly uncaging the PG via near-infrared (NIR) light illumination. In the circulatory system, the cell penetrability of PSP was hindered. In contrast, the asparagine–glycine–arginine (NGR) peptide moieties, selectively bind to CD13-positive tumors, were attached to the nanocarrier to facilitate the active accumulation of this liposomal carrier in tumor tissue. The dual-modified liposomes (PSP/NGR-L) were prepared by emulsification method, and the concentrations of DSPE-PEG₂₀₀₀-psCPP and DSPE-PEG₅₀₀₀-NGR in the liposomes were chosen to be 4% and 1% (molar ratio), respectively. The mean particle size of the PSP/NGR-L was about 95?nm, and the drug entrapment efficiency was more than 90%. Cellular uptake results demonstrated that the proposed PSP/NGR-L had an enhancement of cancer cell recognition and specific uptake. Furthermore, the PSP/NGR-L demonstrated a stronger antitumor efficacy in the HT-1080 tumor model in nude mice with the aid of NIR illumination.     

Preparation,characterization and evaluation of multi-component-loaded liposomes containing Tat-TOS,phospholipase D inhibitor and doxorubicin

In the present study, we aimed to co-load the α-TOS conjugate Tat-TOS with the phospholipase D inhibitor FIPI and the antitumor drug doxorubicin (DOX) in a liposome delivery system for antitumor metastasis. Firstly, Tat-TOS was synthesized by solid-phase synthesis, and its structure was confirmed. The ability of free and liposomal Tat-TOS to induce apoptosis in vitro was evaluated by flow cytometry. Biodistribution of Tat-TOS-loaded liposomes was investigated by a molecular imaging system. Multi-component-loaded liposomes modified with Tat-TOS containing FIPI and DOX was prepared by thin film dispersion method in combination with pH gradient method and post-insertion method. Physicochemical properties were determined, and the in vitro uptake ability of the formulations was evaluated. The results showed that the prepared liposomes were characterized by a uniform particle size distribution and small particle size. The encapsulation efficiency of FIPI and DOX exceeded 85%. Both free and liposomal Tat-TOS significantly improved the activity of inducing apoptosis of tumor cells. The liposomes modified with Tat-TOS were apparently accumulated in normal lung tissue and tumor metastasized lung. Multi-component-loaded liposomes exhibited the strongest cell uptake capacity, suggesting a stronger anti-metastatic effect and anti-tumor activity in vivo.     

In vitro cytotoxicity of Stealth liposomes co-encapsulating doxorubicin and verapamil on doxorubicin-resistant tumor cells

Multidrug resistance (MDR) is a major obstacle to successful clinical cancer chemotherapy. A novel doxorubicin anti-resistant Stealth liposomes (DARSLs), prepared by co-encapsulating doxorubicin (DOX) and verapamil (VER) into stealth liposomes, has been developed. The average particle size of DARSLs was 118.1+/-22.3 nm. Encapsulation efficiencies of DOX and VER in DARSLs were greater than 95% and 70%, respectively. The IC(50) of DARSLs as measured by 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl tetrazolium bromide (MTT) assay in multidrug resistant rat prostate cancer Mat-LyLu-B2 (MLLB2) cells was 0.079+/-0.017 microM, 13 fold less than that for liposomal DOX with free VER (LDFV 0.96+/-0.46 microM) but only about 2 times less than FDFV. The IC(50) cytotoxicity on MLLB2 cells of the various formulations was as follows: DARSLs approximately LDLV相似文献   

Pharmacokinetic/pharmacodynamic modeling of antitumor agents encapsulated into liposomes

Pharmacokinetic/pharmacodynamic (PK/PD) modeling of antitumor agents has been developed for doxorubicin (DOX) in order to predict the optimum conditions for a drug carrier to maximize the antitumor effect. A PK model was constructed for free and liposomal doxorubicin using a hybrid model wherein the disposition in the whole body is described by compartment models, which were linked to the tumor compartment via the blood flow rate. The PD model for doxorubicin was described by a cell-kill kinetic model, which represents the number of tumor cells quantitatively, as a function of the free concentration of doxorubicin in the tumor compartment. The influence of each parameter on the antitumor effects was examined by sensitivity analysis based on the PK/PD model, which clearly showed the importance of optimizing the release rate of DOX from liposomes. The validity of the model has been tested using animal experiments. Preliminary simulations were also performed for humans after scaling up the PK/PD model from rodents to humans. The optimum conditions in the rate of drug release from liposomes were different for rodents vis-a-vis humans, which indicates the limitations involved in extrapolating optimum conditions for experimental animals to those for humans.     

Targeting combinations of liposomal drugs to both tumor vasculature cells and tumor cells for the treatment of HER2-positive breast cancer

Purpose: We used two ligand-modified liposomal drugs to selectively deliver two different chemotherapeutics to tumor cells (TC) and tumor vasculature endothelial (TV) cells, and examined the therapeutic effect of altering the order of treatment administration, and the effect of the temporal spacing of the treatments on the accumulation of a second dose of liposomes and therapeutic activity.

Methods: Studies were completed in an orthotopic mouse model of human epidermal growth factor receptor 2 (HER2)-positive breast cancer, utilizing liposomal doxorubicin, targeted to TC via αHER2 Fab′ fragments, and liposomal vincristine, targeted to CD13 on TV cells via NGR peptides.

Results and discussion: Combination treatment with TV-targeted plus TC-targeted therapies was therapeutically superior to either single agent; switching the order of administration of the combination did not alter treatment efficacy. The tumor accumulation of a second dose of liposomes was increased if administered at 4 days after pre-treatment with TV-targeted therapy. Using a treatment schedule exploiting this increase, the dose of simultaneously administered combination therapy was halved without compromising therapeutic effect.

Conclusion: Proof-of-concept studies revealed the therapeutic potential of a dual-targeted two drug approach against HER2-positive breast cancer, and may be applicable to the treatment of other solid tumors.     

阿霉素水溶液与阿霉素脂质体的抗癌活性和毒性考察

简要介绍了冻干霉素脂质体的制备工艺,并进行了毒性和抗癌活性的考察,与游离阿霉素相比,冻干阿霉素脂质体毒性降低,ＬＤ５０由１１０ｍｇ／ｋｇ增大到１５１ｍｇ／ｋｇ,并保持或提高了抗癌活性．     

Cell-penetrating peptide-doxorubicin conjugate loaded NGR-modified nanobubbles for ultrasound triggered drug delivery

A new drug-targeting system for CD13⁺ tumors has been developed, based on ultrasound-sensitive nanobubbles (NBs) and cell-permeable peptides (CPPs). Here, the CPP-doxorubicin conjugate (CPP-DOX) was entrapped in the asparagine–glycine–arginine (NGR) peptide modified NB (CPP-DOX/NGR-NB) and the penetration of CPP-DOX was temporally masked; local ultrasound stimulation could trigger the CPP-DOX release from NB and activate its penetration. The CPP-DOX/NGR-NBs had particle sizes of about 200?nm and drug entrapment efficiency larger than 90%. In vitro release results showed that over 85% of the encapsulated DOX or CPP-DOX would release from NBs in the presence of ultrasound, while less than 1.5% of that (30?min) without ultrasound. Cell experiments showed the higher cellular CPP-DOX uptake of CPP-DOX/NGR-NB among the various NB formulations in Human fibrosarcoma cells (HT-1080, CD13⁺). The CPP-DOX/NGR-NB with ultrasound treatment exhibited an increased cytotoxic activity than the one without ultrasound. In nude mice xenograft of HT-1080 cells, CPP-DOX/NGR-NB with ultrasound showed a higher tumor inhibition effect (3.1% of T/C%, day 24), longer median survival time (50 days) and excellent body safety compared with the normal DOX injection group. These results indicate that the constructed vesicle would be a promising drug delivery system for specific cancer treatment.     

Immunoliposomal delivery of doxorubicin can overcome multidrug resistance mechanisms in EGFR-overexpressing tumor cells

Immunoliposomes (ILs) can be constructed to target the epidermal growth factor receptor (EGFR) to provide efficient intracellular drug delivery in tumor cells. We hypothesized that this approach might be able to overcome drug resistance mechanisms, which remain an important obstacle to better outcomes in cancer therapy. ILs were evaluated in vitro and in vivo against EGFR-overexpressing pairs of human cancer cells (HT-29 and MDA-MB-231) that either lack or feature the multidrug resistance (mdr) phenotype. In multidrug-resistant cell lines, ILs loaded with doxorubicin (DOX) produced 19–216-fold greater cytotoxicity than free DOX, whereas in nonresistant cells, immunoliposomal cytotoxicity of DOX was comparable with that of the free drug. In intracellular distribution studies, free DOX was efficiently pumped out of the multidrug-resistant tumor cells, whereas immunoliposomal DOX leads to 3.5–8 times higher accumulation of DOX in the cytoplasm and 3.5–4.9 times in the nuclei compared with the free drug. Finally, in vivo studies in the MDA-MB-231 Vb100 xenograft model confirmed the ability of anti-EGFR ILs-DOX to efficiently target multidrug-resistant cells and showed impressive antitumor effects, clearly superior to all other treatments. In conclusion, ILs provide efficient and targeted drug delivery to EGFR-overexpressing tumor cells and are capable of completely reversing the multidrug-resistant phenotype of human cancer cells.     

Immunoliposomal delivery of doxorubicin can overcome multidrug resistance mechanisms in EGFR-overexpressing tumor cells

Immunoliposomes (ILs) can be constructed to target the epidermal growth factor receptor (EGFR) to provide efficient intracellular drug delivery in tumor cells. We hypothesized that this approach might be able to overcome drug resistance mechanisms, which remain an important obstacle to better outcomes in cancer therapy. ILs were evaluated in vitro and in vivo against EGFR-overexpressing pairs of human cancer cells (HT-29 and MDA-MB-231) that either lack or feature the multidrug resistance (mdr) phenotype. In multidrug-resistant cell lines, ILs loaded with doxorubicin (DOX) produced 19-216-fold greater cytotoxicity than free DOX, whereas in nonresistant cells, immunoliposomal cytotoxicity of DOX was comparable with that of the free drug. In intracellular distribution studies, free DOX was efficiently pumped out of the multidrug-resistant tumor cells, whereas immunoliposomal DOX leads to 3.5-8 times higher accumulation of DOX in the cytoplasm and 3.5-4.9 times in the nuclei compared with the free drug. Finally, in vivo studies in the MDA-MB-231 Vb100 xenograft model confirmed the ability of anti-EGFR ILs-DOX to efficiently target multidrug-resistant cells and showed impressive antitumor effects, clearly superior to all other treatments. In conclusion, ILs provide efficient and targeted drug delivery to EGFR-overexpressing tumor cells and are capable of completely reversing the multidrug-resistant phenotype of human cancer cells.     

Cytotoxic and Antitumor Activities of Doxorubicin Conjugates with the Epidermal Growth Factor and its Receptor-binding Fragment

The epidermal growth factor (EGF) receptor is expressed at high levels on many types of tumor cells, such as squamous carcinoma, breast cancer and endothelial cells. We studied targeted delivery of the anticancer drug doxorubicin (DOX) using EGF and its receptor-binding fragment (EGFfr) to cells able to overexpress EGF receptors. EGF-DOX and EGFfr-DOX conjugates were synthesized via a glutaraldehyde bridge. The cytotoxic activities (CTA) of the conjugates were studied in vitro in different tumor cell lines (MCF-7 Wt, MCF-7 AdrR, B16) and endothelial cells using MTT-test. The antitumor effects of the conjugates were examined in vivo in mice with a subcutaneous B16 model. In the case of MCF-7 Wt cells, CTA of EGF-DOX and EGFfr-DOX conjugates exceeded 7.7- and 68-fold that of free DOX. Besides, the conjugates effectively decreased the drug resistance of MCF-7 AdrR cells. CTA of the conjugates against endothelial cell cultures markedly exceeded that of free DOX. It is of note that proliferating endothelial cells were much more sensitive to the effects of the conjugates than confluent endothelial cells. Administration of EGF-DOX and EGFfr-DOX conjugates significantly inhibited tumor growth and increased the mean life span of experimental animals by 46 and 48.5%, respectively.     

Cytotoxic and antitumor activities of doxorubicin conjugates with the epidermal growth factor and its receptor-binding fragment

The epidermal growth factor (EGF) receptor is expressed at high levels on many types of tumor cells, such as squamous carcinoma, breast cancer and endothelial cells. We studied targeted delivery of the anticancer drug doxorubicin (DOX) using EGF and its receptor-binding fragment (EGFfr) to cells able to overexpress EGF receptors. EGF-DOX and EGFfr-DOX conjugates were synthesized via a glutaraldehyde bridge. The cytotoxic activities (CTA) of the conjugates were studied in vitro in different tumor cell lines (MCF-7Wt, MCF-7AdrR, B16) and endothelial cells using MTT-test. The antitumor effects of the conjugates were examined in vivo in mice with a subcutaneous B16 model. In the case of MCF-7Wt cells, CTA of EGF-DOX and EGFfr-DOX conjugates exceeded 7.7- and 68-fold that of free DOX. Besides, the conjugates effectively decreased the drug resistance of MCF-7AdrR cells. CTA of the conjugates against endothelial cell cultures markedly exceeded that of free DOX. It is of note that proliferating endothelial cells were much more sensitive to the effects of the conjugates than confluent endothelial cells. Administration of EGF-DOX and EGFfr-DOX conjugates significantly inhibited tumor growth and increased the mean life span of experimental animals by 46 and 48.5%, respectively.     

Development of 5-FU and Doxorubicin-Loaded Cationic Liposomes against Human Pancreatic Cancer: Implications for Tumor Vascular Targeting

Purpose Human pancreatic adenocarcinoma is a major leading cause of cancer mortality in the United States. Given that current strategies are relatively ineffective against this disease, new treatments are being developed. Liposomes possessing relatively high cationic lipid content preferentially accumulate in tumor angiogenic vessels compared to vessels in normal tissues. We therefore seek to develop cationic liposomes for targeting pancreatic tumor vessels. Materials and Methods We report development of 5-fluorouracil (5-FU) and doxorubicin hydrochloride (DOX) loaded in PEGylated cationic liposomes (PCLs). We evaluate cell association, intracellular fate, and cytotoxicity. Human pancreatic cancer cells HPAF-II and Capan-1, and endothelial cells HMEC-1 and HUVEC were used in this study. Intratumoral distribution of PCLs in (HPAF-II) tumors was determined by intravital microscopy. Results HUVEC and HMEC-1 were most susceptible to 5-FU after 24 and 48 h, compared to HPAF-II and Capan-1. We observed >90% incorporation of 5-FU and DOX in PCLs for 3–20 mol% preparations, with reduced incorporation for >20 mol% formulations. PCLs showed significantly higher association with human endothelial versus pancreatic cancer cells, and improved growth inhibitory properties of DOX. Intravital microscopy revealed distribution of PCLs along HPAF-II vessels. Conclusions Targeting human pancreatic cancer with PCLs may represent a rational alternative to conventional strategies.     

Effect of linalool as a component of Humulus lupulus on doxorubicin-induced antitumor activity

As malignant neoplasm is a major public health problem, there is a need for the development of a novel modulator that enhances antitumor activity and reduces adverse reactions to antitumor agents. In this study, the effects of some volatile oil components in Humulus lupulus on doxorubicin (DOX) permeability in tumor cells and DOX-induced antitumor activity were examined. In vitro, DOX levels in tumor cells by combined linalool as its component significantly increased in the DOX influx system, and the increased effect by linalool on DOX cytotoxicity was shown. In vivo, the combination of DOX with linalool significantly decreased tumor weight compared with that of DOX alone treated group. The promotion of DOX influx level by combined linalool did not depend on energy, whereas it was suppressed by the absence of Na⁺. This promoting effect was suppressed by the presence of S-(4-nitrobenzyl)-6-thioinosine and inhibited dependently on phlorizin concentration. It is considered that linalool promoted DOX influx in tumor cells because of its action on DOX transport through concentrative Na⁺-dependent nucleoside transporter 3, which increased DOX concentration in tumor cells and thus enhanced the antitumor activity of DOX. Therefore, linalool as a food component is anticipated to be an effective DOX modulator.     

Anserine induced advantage effects on the antitumor activity of doxorubicin.

It is hoped that the strategy for the increase of antitumor activity by the combination of foods or their components will take quality of life into consideration. We examined whether anserine, is a dipeptide in foods, has beneficial effects on the doxorubicin (DOX) induced antitumor activity in vitro and in vivo. Anserine increased the DOX induced antitumor activity by the maintained DOX concentration in the tumor in vivo. On the other hand, anserine has no effect on the DOX concentration in normal tissues. Namely, it is expected that anserine will not increase the DOX induced adverse reaction. Thus, anserine appeared to increase the antitumor activity of DOX with an increased DOX concentration in the tumor by specific action on the tumor. Furthermore, anserine significantly induced DOX influx compared to that of the DOX alone group in vitro. It is speculated that the anserine induced increase in the antitumor activity of DOX in vivo was affected by the promotion of DOX influx into the tumor cells in vitro. Anserine was considered to take into tumor cells via a dipeptide transporter, and it resulted in an increase of the DOX influx. Anserine did not affect on the activity of the CYP3A subtype as a DOX metabolizing enzyme. Namely, it was expected that anserine increased the antitumor activity of DOX by the change of the DOX concentration without the changing metabolism of DOX.