Induction of Apoptosis by Hybrid Liposomes for Human Breast Tumor Cells along with Activation of Caspases

Abstract

It is well known that liposomes are used as drug carriers: examples are antitumor agents, hormones, and immunomodulation. 1,2) On the other hand, we have recently produced specific hybrid liposomes composed of vesicular and micellar molecules; they are stable for a longer period. The physical properties of these liposomes such as size, membrane fluidity, phase transition temperature, and hydrophobicity can be controlled by changing the constituents and compositional ratios of hybrid liposomes. 3,4) In the course of our study on hybrid liposomes, the following interesting results were obtained. (a) Stereochemical control of the enantioselective hydrolysis of amino acid esters could be established by temperature regulation and by changing the composition of hybrid liposomes. 9) (d) No toxicity of the hybrid liposomes was observed in normal cells in vitro nor in normal rats in vivo. 8,10) In this study, we report on hybrid liposomes composed of L-a -dimyristoylphosphatidylcholine (DMPC) and polyoxyethylenedodecyl ether (C 12 (EO) n : CH 3 (CH 2 ) 11 O(CH 2 CH 2 O) n H) having inhibitory effects on the growth of human breast tumor cells (MDA-MB-453) in vitro along with apoptosis.Hybrid liposomes were prepared by sonication (VELVO VS-N300, 300W) of a mixture containing 95 mol% DMPC and 5 mol% C 12 (EO) n in 5% glucose solution at 45°C with 300W, followed by filtration with a 0.20 mm filter.First, we examined the fifty percent inhibitory concentration (IC 50 ) of hybrid liposomes (HL-n) on the growth of MDA-MB-453 cells in vitro on the basis of WST-1 assay. 11)The tumor cells (5.0ϫ10 4 viable cells/ml) were cultured for 48 h in an incubator at 37°C after adding the sample solutions. WST-1 solutions were added and the absorbance at wavelength of 450 nm was measured by spectrophotometer. The inhibitory concentration was evaluated by A mean / A control , where A mean and A control denote the absorbance of water-soluble formazan, which was useful as an indicator of cell viability, in the presence and absence of sample solutions, respectively. The results are shown in Fig. 1. The IC 50 values of HL-n were from one seventh to a half of those of the DMPC liposomes, indicating that the inhibitory effects of hybrid liposomes are large when compared with those of the DMPC liposomes.Morphology of hybrid liposomes (HL-n) was examined on the basis of dynamic light scattering measurements. Hydrodynamic diameter (d hy ) of HL-n was 80-120 (HL-21 and 23) and 90-110 nm (HL-25), which remained stable for more than three weeks. On the other hand, it was found that DMPC liposomes, HL-4 and HL-10 were unstable. It is worthy to note that HL-n (nϭ21, 23, 25) having a diameter of 100 nm could avoid the clearance by reticular endothelial system in vivo. 12)Second, we examined the mechanism for inhibiting the growth of MDA-MB-453 cells in vitro. Fluorescence micrographs of MDA-MB-453 cells using TUNEL method after the treatment with hybrid liposomes are shown in Fig. 2. The green color (FITC) was observed in the cells after adding hybrid lipos...

Remarkable inhibitory effects of hybrid liposomes on growth of human colon cancer cells through induction of cell cycle arrest along with apoptosis

“…It has been already elucidated that hybrid liposomes induce apoptosis in various tumor cells, with activations of caspases-3, -8, and -9, and reduction of mitochondria membrane potential. 8,[11][12][13]16 HL-n could probably fuse and accumulate into HCT116 cells, and induce apoptosis through activation of caspase cascades.…”

“…Inhibitory effects of hybrid liposomes composed of L-α-dimyristoylphosphatidylcholine (DMPC) and polyoxyethylene (20) sorbitan monolaurate (Tween 20) including antitumor drugs such as 1,3-bis(2-chloroethyl)-1-nitrosourea on the growth of glioma cells in vitro and in vivo have been observed. 5 On the other hand, hybrid liposomes composed of DMPC and polyoxyethylene(n) alkyl ethers without any drugs demonstrated remarkable inhibitory effects on the growth of various tumor cells in vitro [6][7][8] and in vivo. [9][10][11][12] In addition, it has been demonstrated that hybrid liposomes could induce apoptotic cell death in leukemia, 13 hepatoma, 7 lung cancer, 14 breast cancer, 8 and primary effusion lymphoma cells.…”

“…5 On the other hand, hybrid liposomes composed of DMPC and polyoxyethylene(n) alkyl ethers without any drugs demonstrated remarkable inhibitory effects on the growth of various tumor cells in vitro [6][7][8] and in vivo. [9][10][11][12] In addition, it has been demonstrated that hybrid liposomes could induce apoptotic cell death in leukemia, 13 hepatoma, 7 lung cancer, 14 breast cancer, 8 and primary effusion lymphoma cells. 15 With respect to colon cancer cell lines, hybrid liposomes induced apoptosis in human colon adenocarcinoma WiDr 16 and mouse colon carcinoma Colon26 cells in vitro.…”

Inhibitory Effects of Hybrid Liposomes on the Growth of Non-small Cell Lung Carcinoma Cells and Anti-invasive Activity by Ceramide Generation without any Drugs

“…The physical properties of HL such as shape, size, membrane fluidity of phase transition can be controlled by changing the constituents and compositional ratio. Remarkably high inhibitory effects of HL composed of DMPC and polyoxyethylene(n) dodecyl ethers (C 12 (EO) n ) on the growth of tumor cells in vitro [13][14][15][16][17], in vivo [17][18][19][20][21], and clinical application [22][23][24] have been obtained without drugs. We have reported HL induced apoptosis in various cancer cells including NSCLC (A549, H460, H23 and H520) cells [25].…”

Specific Interaction between Ca2+ and Anionic Lipids in Cancer Cells along with Apoptosis

“…5) With respect to the role of Ca 2ϩ in inhibition of cellular proliferation, it has been reported that Ca 2ϩ imported into the cytoplasm of mammalian cells could lead to a programmed cell death "apoptosis" through several signalling pathways. 6,7) However, the mechanistic details of tumor-specific growth inhibition effects of Ca On the other hand, we have investigated the membrane targeted chemotherapy with hybrid liposomes 8,9) composed of phospholipids and nonionic surfactants for tumor cells in vitro, [10][11][12][13][14][15] in vivo, 15,16) and in clinical applications. 16,17) Significantly, the denaturation of cell membranes by hybrid liposomes could lead to apoptosis in tumor cells without any drugs.…”