The effect of adriamycin against a liver metastatic model by encapsulation in liposomes

Suppression of human hepatocellular cancer cell proliferation by Brucea javanica oil-loaded liposomes via induction of apoptosis

INTRODUCTION

Hepatocellular carcinoma (HCC) is a type of malignancy with high incidence and poor prognosis. Brucea javanica is extracted from Simaroubaceae plants. It is found to have low toxicity but high anti-cancer efficiency. The aim of this study is to determine the effects of Brucea javanica oil-loaded liposomes (BJOL) on human hepatocellular cancer cell line HepG2. The related molecular mechanisms were determined.

MATERIAL AND METHODS

Morphologic changes of HepG2 cells were observed by transmission electron microscope after treatment with BJOL in vitro. Cell proliferation was determined by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay after cell treatment with different doses of BJOL. Flow cytometry was performed. Nude mice were divided into 4 groups randomly and treated with different doses of BJOL. The apoptosis hepatocellular carcinoma was detected by TUNEL.

RESULTS

Proliferation of HepG2 was inhibited significantly by BJOL in a dose-dependent manner (2.5 mg/l or 5 mg/l). Compared with the animal models treated with the negative control, the animal models in the BJOL group had higher weight and lower metastasis rates (p < 0.01). The rate of apoptosis in hepatocellular carcinoma tissue of the BJOL groups was increased when compared with the control group (p < 0.05).

CONCLUSIONS

Brucea javanica oil-loaded liposomes inhibits proliferation of HepG2. The effect appears to be dose-dependent, possibly by inducing apoptosis of cancer cells.

Is cell death a critical end point for anticancer therapies or is cytostasis sufficient?

Since the discovery of conventional chemotherapy and the development of new target-based agents, the importance of cytostasis in anticancer activity has been debated. This review examines the relative importance of both cytostasis and cytotoxicity based on both preclinical data and clinical reports. Several limitations of our basic and clinical methods to evaluate cytostasis and cytotoxicity will be highlighted. Molecular mechanisms of cytostasis will be analyzed, including interference with the cell cycle as well as putative links with necrosis and autophagy. Finally, we will cite evidence that most older and newer compounds are both cytostatic and cytotoxic. The relative role of cytostasis and cytotoxicity on future drug screening and clinical development will be explored.

Lactosaminated and intact N-succinyl-chitosans as drug carriers in liver metastasis

The biodistributions of fluorescently labeled N-succinyl-chitosan (Suc-FTC) and lactosaminated N-succinyl-chitosan (Lac-Suc-FTC) after i.v. administration to mice intravenously inoculated with M5076 cells were investigated at 3 and 12 days post-inoculation. At both time points, Lac-Suc-FTC was specifically localized to the liver. However, the area under the concentration-time curve in the liver decreased gradually by progress of the liver metastasis. At 3 days post-inoculation, Suc-FTC showed good retention in the systemic circulation and was little distributed to the liver. However, at 12 days post-inoculation, Suc-FTC was eliminated relatively fast from the systemic circulation and gradually accumulated in the liver. The antitumor effects of mitomycin C (MMC), Lac-Suc-MMC conjugate (Lac-Suc-MMC) and highly succinylated Suc (Suc(II))-MMC conjugate (Suc(II)-MMC) were examined on single i.v. administration for both metastatic stages. For administration at 3 days post-inoculation, Lac-Suc-MMC alone tended to elongate significantly the lifespan at a lower dose (0.4 mg eq. MMC/kg), and MMC, Suc(II)-MMC and Lac-Suc-MMC increased significantly the lifespan at a higher dose (10 mg eq. MMC/kg). However, at 12 days post-inoculation (late stage of metastasis), neither MMC nor the conjugates were effective even at the higher dose (10 mg eq. MMC/kg). Both carriers, Suc showing systemic long-circulation and Lac-Suc with an ability of liver-specific localization, are thought to be drug carriers with potentialities for therapeutics at early stage of metastasis.

Efficiency of liposomes surface-modified with soybean-derived sterylglucoside as a liver targeting carrier in HepG2 cells

We investigated the interaction of liposomes surface-modified with soybean-derived sterylglucoside (SG) (SG-liposomes) with HepG2 cells in the point of involvement of asialoglycoprotein receptor (ASGP-R) mediated endocytosis and examined the efficiency of SG-liposomes as drug carriers using 1,1'-dioctadecyl-3,3,3',3'-tetramethylindocarbocyanine perchlorate (DiI) as a maker of liposome, carboxylated polystyrene microspheres (Fluoresbrite) as a model drug not taken up in cells and doxorubicin (DXR). SG-liposomes were composed of dipalmitoylphosphatidylcholine (DPPC), cholesterol (Ch) and SG (DPPC/Ch/SG=6:3:1, molar ratio) and DiI, Fluoresbrite and DXR were entrapped in SG-liposomes, respectively. Each SG-liposome was incubated with HepG2 cells at 4 or 37 degrees C, and co-incubated with asialofetuin (AF) as a competitor of ASGP-R. The association of DiI, Fluoresbrite or DXR entrapped in SG-liposomes with HepG2 cells at 37 degrees C was significantly higher than that in liposomes containing no SG. That of DiI and Fluoresbrite was reduced significantly by the incubation with AF, but that of DXR was not affected. These findings suggest that Fluoresbrite behaves like the lipid component of SG-liposomes, but DXR in SG-liposomes does not behave similar to the lipid component of SG-liposomes, thus, its drug behavior released from liposomes may be due to its physicochemical properties. SG-liposomes are potentially useful drug carriers to the liver, because the glucose residue may work as a kind of ligand for ASGP-R.

Interactions of PC/Chol and PS/Chol liposomes with human cells in vitro

Interactions between phosphatidylcholine (PC) or phosphatidylserine (PS) liposomes and human umbilical vein endothelial cells (HUVEC) or human promyelocytic leukemia cells (HL60) were investigated. Pyramine encapsulating or rhodamine incorporating small unilamellar liposomes with mean diameters around 80 nm (demonstrated to retain encapsulated material and to be nontoxic under experimental conditions) were used. Liposome uptake by both types of cells increased when increasing amounts of vesicles were co-incubated. For both lipid compositions, the interaction with HUVEC was very fast (association reached a plateau within 5 min) and so was the release of internalized vesicles (90% within 10 min at 37 degrees C). The reduced association values at 4 degrees C and the punctuate fluorescence observed in the cell cytoplasm after interaction, were indicative of whole liposome internalization. This internalization was clathrin-independent, since it was not inhibited by sodium azide and deoxyglucose. Pre-treatment of HUVEC with filipin or NEM resulted in modification of the interaction, something that could be due to alterations in the biochemical characteristics of HUVEC membranes that inhibit vesicular processes. In HL-60 cells, a slower association and faster release of PC/Chol liposomes was demonstrated, while association of both liposomes with these cells was energy-and temperature-independent. Nevertheless, morphological studies revealed differences in the interactions: A bright fluorescent rim observed after interaction with PC/Chol liposomes, suggests that these liposomes were adsorbed on the surface of HL60 cells, while the uniform cytoplasmic fluorescence observed after incubation with PS/Chol liposomes was indicative of fusion as the interaction mechanism.

Ability of doxorubicin-loaded nanoparticles to overcome multidrug resistance of tumor cells after their capture by macrophages

PURPOSE

Investigation of the ability of doxorubicin-loaded nanoparticles (NP/Dox) to overcome multidrug resistance (MDR) when they have first been taken up by macrophages.

METHODS

The growth inhibition of P388 sensitive (P388) and resistant (P388/ADR) tumor cells was evaluated in a coculture system consisting of wells with two compartments. The tumor cells were seeded into the lower compartment, the macrophages were introduced into the upper part in which the drug preparations were also added.

RESULTS

Doxorubicin exerted lower cytotoxicity on tumor cells in coculture compared with direct contact. In P388/ADR, NP/Dox cytotoxicity was far higher than that of free doxorubicin (Dox). Three different formulations of cyclosporin A (either free (CyA), loaded to nanoparticles (NP/CyA) or in a combined formulation with doxorubicin (NP/Dox-CyA)), were added to modulate doxorubicin efficacy. The addition of cyclosporin A to Dox increased drug cytotoxicity. Both CyA added to NP/Dox and NP/Dox-CyA were able to bypass drug resistance.

CONCLUSIONS

Despite the barrier role of macrophages, NP/Dox remained far more cytotoxic than Dox against P388/ADR. Both NP/Dox + CyA and NP/Dox-CyA allowed to overcome MDR, but the last one should present greater advantage in vivo by confining both drugs in the same compartment, hence reducing the adverse effects.

Liposomal encapsulation of ganciclovir enhances the efficacy of herpes simplex virus type 1 thymidine kinase suicide gene therapy against hepatic tumors in rats

Suicide gene therapy based on ganciclovir (GCV) metabolism by transgene herpes simplex thymidine kinase (HSV-1 TK) has been used to selectively kill proliferating cells in clinical settings such as cancer, vascular restenosis, and immunological disorders. We investigated whether encapsulation of ganciclovir (GCV) into liposomes would improve its efficacy, especially against hepatic tumors. Large unilamellar liposomes containing GCV were prepared by reversed-phase evaporation. Pharmacokinetic studies in rats showed that, compared with free GCV, the intravenous injection of liposome-encapsulated GCV (lip-GCV) led to a faster decrease in GCV plasma concentrations, but higher liver-blood ratios. After treatment of syngeneic HSV-1 TK+ liver metastases in rats, histologically active tumors were found in 95% of the transplanted lesions when physiological saline had been given and in 50% when free GCV had been given at 90.2 microM/kg twice daily. This dose is known to be insufficient for the eradication of HSV-1 TK+ tumors. In contrast, only 5% viable tumors were found in rats receiving lip-GCV at this same concentration. Average tumor volumes were 19 +/- 15, 7 +/- 9, and <1 mm3 for the control, free GCV, and lip-GCV groups, respectively. GCV-related toxicity was no longer observed. The results demonstrate that liposomal encapsulation of GCV is feasible and significantly enhances its efficacy against HSV-1 TK+ hepatic tumors.