Xue Ying

Dual-targeting daunorubicin liposomes improve the therapeutic efficacy of brain glioma in animals

Chemotherapy for brain glioma has been of limited value due to the inability of transport of drug across the blood-brain barrier (BBB) and poor penetration of drug into the tumor. For overcoming these hurdles, the dual-targeting daunorubicin liposomes were developed by conjugating with p-aminophenyl-alpha-D-manno-pyranoside (MAN) and transferrin (TF) for transporting drug across the BBB and then targeting brain glioma. The dual-targeting effects were evaluated on the BBB model in vitro, C6 glioma cells in vitro, avascular C6 glioma tumor spheroids in vitro, and C6 glioma-bearing rats in vivo, respectively. After applying dual-targeting daunorubicin liposomes, the transport ratio across the BBB model was significantly increased up to 24.9%. The most significant uptake by C6 glioma was evidenced by flow cytometry and confocal microscope. The C6 glioma spheroid volume ratio was significantly lowered to 54.7%. The inhibitory rate to C6 glioma cells after crossing the BBB was significantly enhanced up to 64.0%. The median survival time of tumor bearing rats after administering dual-targeting daunorubicin liposomes (22 days) was significantly longer than that after giving free daunorubicin (17 days, P=0.001) or other controls. In conclusion, the dual-targeting daunorubicin liposomes are able to improve the therapeutic efficacy of brain glioma in vitro and in animals.

PEGylated Poly(amidoamine) dendrimer-based dual-targeting carrier for treating brain tumors

A dual-targeting drug carrier (PAMAM-PEG-WGA-Tf) based on the PEGylated fourth generation (G = 4.0) PAMAM dendrimer with transferrin (Tf) and wheat germ agglutinin (WGA) on the periphery and doxorubicin (DOX) loaded in the interior was synthesized and its BBB penetration and tumor targeting properties were explored. DLS and TEM measurements revealed the size of PAMAM-PEG-WGA-Tf was in the range of 14-20 nm. It reduced the cytotoxicity of DOX to the normal cells greatly, while efficiently inhibited the growth rate of the C6 glioma cells. The assay of transport across the BBB showed that PAMAM-PEG-WGA-Tf delivered 13.5% of DOX in a period of 2 h, demonstrating an enhanced transport ratio as compared to the ratio of 8% for PAMAM-PEG-WGA, 7% for PAMAM-PEG-Tf and 5% for free DOX in the same period of time. The accumulation of DOX in the tumor site was increased due to the targeting effects of both Tf and WGA, leading to the complete breakage of the avascular C6 glioma spheroids in vitro.

All-trans retinoic acid stealth liposomes prevent the relapse of breast cancer arising from the cancer stem cells.

The relapse of cancer is mostly due to the proliferation of cancer stem cells which could not be eliminated by a standard chemotherapy. A new kind of all-trans retinoic acid stealth liposomes was developed for preventing the relapse of breast cancer and for treating the cancer in combination with a cytotoxic agent, vinorelbine stealth liposomes. In vitro studies were performed on the human breast cancer MCF-7 and MDA-MB-231 cells. In vivo evaluations were performed on the newly established relapse model with breast cancer stem cells. Results showed that the particle size of all-trans retinoic acid stealth liposomes was approximately 80nm, and the encapsulation efficiency was >90%. Breast cancer stem cells were identified with the CD44(+)/CD24(-) phenotype and characterized with properties: resistant to cytotoxic agent, stronger capability of proliferation, and stronger capability of differentiation. Inhibitory effect of all-trans retinoic acid stealth liposomes was more potent in cancer stem cells than in cancer cells. The mechanisms were defined to be two aspects: arresting breast cancer stem cells at the G(0)/G(1) phase in mitosis, and inducing the differentiation of breast cancer stem cells. The cancer relapse model was successfully established by xenografting breast cancer stem cells into NOD/SCID mice, and the formation and growth of the xenografted tumors were significantly inhibited by all-trans retinoic acid stealth liposomes. The combination therapy of all-trans retinoic acid stealth liposomes with vinorelbine stealth liposomes produced the strongest inhibitory effect to the relapse tumor model. It could be concluded that all-trans retinoic acid stealth liposomes could be used for preventing the relapse of breast cancer by differentiating cancer stem cells and arresting the cell-cycle, and for treating breast cancer as a co-therapy, thus providing a novel strategy for treating breast cancer and preventing relapse derived from breast cancer stem cells.

Enhanced efficacy of functionalized epirubicin liposomes in treating brain glioma-bearing rats.

PURPOSE The restriction of drug transporting across the blood-brain barrier (BBB) and the limit of drug penetrating into the tumor tissue remain the major obstacles for brain tumor chemotherapy. In the present study, we developed a functionalized liposomal nanoconstruct, epirubicin liposomes modified with tamoxifen (TAM) and transferrin (TF), for transporting drug across the BBB and afterwards targeting the brain glioma. METHODS Evaluations were performed on the murine C6 glioma cells, the C6 glioma spheroids, the BBB model in vitro and the brain glioma-bearing rats. RESULTS When compared with controls, epirubicin liposomes modified with TAM and TF showed the strongest inhibitory effect to C6 glioma cells or glioma spheroids in vitro, significant transport ability across the BBB model in vitro, an evident effect of targeting the brain tumor cells in vitro, and an extended median survival time in the brain glioma-bearing rats. CONCLUSION Epirubicin liposomes modified with TAM and TF significantly improve the therapeutic efficacy of brain glioma in vitro and in animals, hence providing a new strategy for brain tumor chemotherapy.

Targeted delivery of a combination therapy consisting of combretastatin A4 and low-dose doxorubicin against tumor neovasculature

UNLABELLED The present study demonstrates the applicability of a novel strategy that employs targeted delivery of combined treatment against tumor neovasculature. Briefly, a ligand of integrins, cyclic arginine-glycine-aspartic acid-tyrosine-lysine pentapeptide (cRGDyK), was conjugated to the PEG end of polyethylene glycol-b-poly lactic acid (PEG-b-PLA), and doxorubicin was chemically linked to the PLA end of PEG-b-PLA. The targeted dual-drug micelle system was prepared by mixing combretastatin A4 (an antivascular agent), PEG-b-PLA, and the above two conjugates using a solution-casting method. The targeted micelles significantly enhanced cellular uptake of the drug by B16-F10 cells and human umbilical vein endothelial cells through a receptor-mediated endocytosis. The cRGDyK-modified dual-drug system achieved an optimal antitumor effect, lifespan increase, antineovasculature, antiproliferation, and apoptosis induction, revealing the advantage of active targeting and the modified combination therapy. In conclusion, the integration of targeted delivery and combination therapy against tumor neovasculature represents a promising approach for cancer treatment. FROM THE CLINICAL EDITOR A ligand of integrins was conjugated to PEG-b-PLA, and doxorubicin was chemically linked to the PLA. Efficiency was demonstrated in a cancer model. The integration of targeted delivery and combination therapy against tumor neovasculature represents a promising approach for cancer treatment.

Targeting therapy with mitosomal daunorubicin plus amlodipine has the potential to circumvent intrinsic resistant breast cancer.

Intrinsic resistance of cancers is a major cause of failure in chemotherapy. We proposed here a strategy to overcome intrinsic resistance by constructing cancer cell mitochondria-specifically targeting drug-loaded liposomes, namely, mitosomal daunorubicin plus amlodipine. Anticancer agent daunorubicin and apoptotic inducer amlodipine were loaded together into the mitosomes, and targeting molecule dequalinium was modified on the surface. Evaluations were performed on the breast cancer MCF-7 and resistant MCF-7/adr cells and in animals. Mitosomal daunorubicin plus amlodipine were about 97 nm, selectively accumulated in mitochondria, induced the swelling and disruption of mitochondria, dissipated the mitochondrial membrane potential, released a large amount of cytochrome C by translocation, cleaved Bid, and initiated a cascade of caspase 8 and 3 reactions. A robust anticancer effect was evidenced in vivo. Mitochondria-specifically targeting drug-loaded liposomes would provide a new strategy for treating resistant cancers.

The efficacy of mitochondrial targeting antiresistant epirubicin liposomes in treating resistant leukemia in animals

Background Multidrug resistance (MDR) of cancers can be circumvented by inducing programmed cell death, which is known as apoptosis. Mitochondria play a crucial role in apoptosis. Mitochondria-specific therapy would provide an efficient strategy for treating resistant cancers. Design and methods A strategy was proposed here to overcome MDR by designing cancer mitochondria-specific drug-loaded liposomes, namely, antiresistant epirubicin mitosomes, aimed at treating resistant leukemia by targeting mitochondria. Evaluations were performed on human chronic leukemia K562, MDR K562/ADR cells, and female BALB/c nude mice xenografted with MDR K562/ADR cells. The liposomes were characterized through assays of cytotoxicity, mitochondrial targeting, caspase-9 and caspase-3, antitumor activities, and TUNEL (terminal deoxynucleotidyl transferase dUTP nick end labeling) analysis. Results The average size of antiresistant epirubicin mitosomes was in the range of 105–115 nm. Antiresistant epirubicin mitosomes were effective in inhibiting proliferation of MDR K562/ADR cells in vitro and selectively accumulated into the mitochondria. Caspase-9 and caspase-3 activity was increased after applying antiresistant epirubicin mitosomes. In xenografted resistant MDR K562/ADR tumor in nude mice, antiresistant tumor effect of antiresistant epirubicin mitosomes was evidently observed. Apoptotic inducing effects by antiresistant epirubicin mitosomes were noticeably evidenced via mitochondrial pathway. Conclusions Antiresistant epirubicin mitosomes had significant inhibitory effect against resistant leukemia in vitro and in vivo, hence providing a promising strategy for improving therapeutic efficacy in resistant human leukemia.

Pharmacokinetics and Tissue Distribution of Dual-Targeting Daunorubicin Liposomes in Mice

Background: To circumvent the problem of transporting anticancer drugs across the blood-brain barrier (BBB) to target brain tumors, we have previously developed dual-targeting daunorubicin liposomes modified with 4-aminophenyl-α-D-manno-pyranoside and transferrin molecules. The objective of the present study was to evaluate the pharmacokinetics and distribution of daunorubicin after intravenous administration of dual-targeting daunorubicin liposomes. Methods: We evaluated pharmacological parameters in normal KunMing mice. Drug concentrations in plasma, heart, spleen, lung, kidney and brain were measured using HPLC-UV. Results: The plasma drug concentration-time profile of the daunorubicin dual-targeting liposomes decreased more slowly than free daunorubicin in the initial phase and maintained higher drug levels in the terminal phase, resulting in longer blood exposure to daunorubicin liposomes compared with the free drug. Daunorubicin levels were lower in heart tissue and significantly higher in brain tissue after administration of the dual-targeting liposomes compared with the free drug. Daunorubicin was detected at varying levels in the liver, spleen, lung and kidney tissues. Conclusion: Our results indicate that dual-targeting daunorubicin liposomes improve the daunorubicin blood circulation time and show an enhanced drug transport potential across the BBB.