Tumor Tissue Of Tumor-bearing Mice Research Articles

Cooperative effect of Bifidobacteria lipoteichoic acid combined with 5-fluorouracil on hepatoma-22 cells growth and apoptosis

To investigate the cooperative effect of Bifidobacteria lipoteichoic acid (BLTA) combined with 5-fluorouracil on tumor cells growth and apoptosis in mice bearing H22. Hepatoma-22 (H22) cells were cultured in RPMI1640. Establish tumor-bearing mice model of liver cancer by injecting intraperitoneally 1×10(6)/mL cells into the above-mentioned Balb/c mice. 5-FU alone, BLTA alone or BLTA in combination with 5-FU were used to treat tumor-bearing mice. The tumor size were observed and measured regularly. The growth-inhibiting rate (IR) of tumor was detected. Real-Time PCR and Western blot were used to detect Bcl-2, Bax and Caspase-3 expressions of mRNA and protein in tumor tissue of tumor-bearing mice. Detection of apoptotic cells in tumor tissue by HE staining analysis. Detection of the organ index was for evaluate the added-activity of immune organs in mouse. FCM was used to detect T subgroup ratio of spleen cells of tumor-bearing mice. Expression change of mRNA and proteins of Foxp3 and TIM-3 were detected by Real-Time PCR and Western blot in tumor-bearing mice tumor tissue. BLTA and 5-FU significantly inhibited the proliferation of tumor and induced obvious apoptosis, the combined effects were greater than those of the individual agents (P<0.01). The underlying molecular mechanism of apoptotic process could be up-regulation of Bax and down-regulation of Bcl-2 and Caspase-3. The HE staining indicated that combined treat could both induce tissue cells necrosis and increase immune cells infiltration. Organ index showed that BLTA can enhance the proliferation of immune organs. The ratio of CD4(+)CD25(+) Treg significantly decreased and CD4(+) T cell increased in BLTA and 5-FU group (P<0.01). Compared to NS group, mRNA and proteins expression of Foxp3 and TIM-3 down regulated in BLTA and 5-FU group (P<0.01). These results show that combined effects of Bifidobacteria lipoteichoic acid and 5-FU on H22 cells were superior to the individual. The combination did not only increase anti-tumor effect, but also could alleviate the side effects of chemotherapy, with inhibiting TIM-3/TIM-3L pathway, cutting down immunosuppressive activity of CD4(+)CD25(+) Treg and enhancing cell-mediated immunity.

Effects of Apigenin on the Expressions of TGF-β1R II, NF-κB and VEGF Genes in Tumor Tissues of Mice with H29 Colon Cancer

To observe the effects of Apigenin on the expressions of TGF-β1R II, NF-κB and VEGF genes in tumor tissues of mice with H29 colon cancer. Fifty ICR mice with H29 colon cancer were randomly divided into five groups: normal saline group, low-dose Apigenin group, middle-dose Apigenin group and high-dose Apigenin group and cyclophosphamide group. The mice were killed on the next day of administration discontinuance, and subcutaneous tumor tissues were collected. Quantitative fluorescence RT-PCR was used to detect the expression of TGF-β1R II, NF-κB and VEGF genes in tumor tissues of H29 colon cancer mice. Apigenin raised the expression level of TGF-β1R II in H29 colon cancer tissues, which showed the most obvious effect in the middle-dose group, with a significant difference compared with the normal saline group (P<0.01). The Apigenin group of each dose could significantly lower the NF-κB expression level in H29 colon solid tumors, showing significant differences compared with the normal saline group (P<0.01). The middle-dose and high-dose Apigenin groups could significantly reduce the level of VEGF expression in tumor tissues of ICR mice with H29 colon cancer, and the high-dose group had most obvious effect, and there were significant difference among the middle-dose group, high-dose group and the normal saline group (P<0.01). The mechanism of anti-tumor effect of Apigenin might be the reason that Apigenin can raise the expression level of TGF-β1R II by down-regulating the expression of NF–κB and VEGF in tumor tissues of tumor-bearing mice, thereby inhibiting tumor angiogenesis and tumor cell proliferation, so as to achieve the anti-tumor effect.

Effect of luteolin on gene expression in mouse H22 hepatoma cells.

The purpose of our study was to observe the effects of luteolin on the expression of the genes ICAM-1, LFA-3, and PCNA in H22 hepatoma tissue. Sixty ICR (Institute of Cancer Research) mice with H22 hepatoma were randomly divided into five groups: a normal saline control group, low-, medium-, and high-dose luteolin groups, and a cyclophosphamide group. The mice were euthanized the day after administration withdrawal and subcutaneous tumor tissue was extracted. Quantitative fluorescence RT-PCR was used to detect the expression of ICAM-1, LFA-3, and PCNA in H22 hepatoma tissue in the mice. Luteolin was found to up-regulate the expression of ICAM-1 in H22 hepatoma tissue, of which the middle-dose group had the most obvious effect, showing a significant difference (P < 0.01) as compared to the normal saline group. Each dose group of luteolin significantly down-regulated the expression of LFA-3 in H22 hepatoma tissue, showing significant differences as compared to the saline control group (P < 0.01). The medium- and high-dose luteolin groups significantly reduced the expression of PCNA in H22 hepatoma tissue of ICR mice, where the effect of the high-dose group was the most obvious, and the difference between the two luteolin groups and the normal saline group was statistically significant (P < 0.01). Luteolin may inhibit tumor angiogenesis and tumor cell proliferation by down-regulation of LFA- 3 and PCNA and up-regulation of ICAM-1 in tumor tissue of tumor-bearing mice, thereby achieving its anti-tumor effect.

Malignant transformation of fusion cells derived from co-culturing human glioma cell line SU3 with murine macrophages

Objective To investigate whether the malignant transformation of macrophages （ Mφ） in glioma mesenchyme was induced by the fusion of glioma cells （ SU3 ） and Mφ.Methods SU3 cells transfected with red fluorescent protein genes were co-cultured in vitro with Mφexpressing enhanced green fluorescent protein.The cell lineages with RFP＋/GFP＋dual-color fluorescence were established by using monoclonal selection method.A series of tests for analyzing cancer-related phenotypes, tumorigenicity and specific markers for murine macrophage were performed.Results （1） A few of dual-color fluorescent cells were observed in the co-culture.Three monoclonal cell lineages （C3, C4 and C12） were obtained success-fully.（2） Three types of cells including RFP＋, EGFP＋and RFP＋/EGFP＋cells were formed during the cul-ture of monoclonal C12 cell lineage.The percentage of EGFP＋cells was increased along the extended culture time and increased passages.Then, EGFP＋cells gradually became the predominant cell population.Nota-bly, the percentage of RFP＋/EGFP＋cells were decreased and maintained at a low level, but the RFP＋cells almost disappeared.（3） EGFP＋cells from monoclonal C12 cell lineage showed the malignant characteristics such as loss of contact inhibition, rapid proliferation andchromosome aneuploidy, as well as high tumorigenic rate in nude mice （5/5）.They also expressed macrophage specific marker CD68 and showed a large number of telocentric chromosomes.Conclusion The results of this study suggested that the malignant transforma-tion of host macrophages as previously observed in solid tumor might be induced by cell fusion occurred be-tween human glioma cells and macrophages.Along with the previous evidences showing the isolation of the malignantly transformed macrophages （ ihCTC） from solid tumor tissue of tumor-bearing mice, the results confirmed an objective existence of malignant transformation of host macrophages in tumor microenvironment. The malignant transformation of host cells induced by fusion with tumor cells revealed not only a new under-standing for the progression of tumor and cancer heterogeneity, but also new targets for cancer therapy. Key words: Glioma stem cells; Fluorescent nude mice; Macrophages; Cell fusion; Host cell ma-lignant transformation

유방암 세포(EMT6) 이식 마우스에서 녹차폴리페놀 음용이 시스플라틴의 암 조직 성장 억제에 미치는 영향

본 연구는 녹차폴리페놀이 시스플라틴의 항암작용과 신장독성에 미치는 영향을 유방암 세포(EMT6)와 암세포 이식 마우스를 이용하여 in vitro와 in vivo 실험으로 관찰하였다. 배양한 EMT6 세포에서 녹차폴리페놀은 시스플라틴에 의한 세포 독성을 증가시켰다. 마우스에 EMT6 세포를 주사하여 유발된 종양의 크기가 시스플라틴군(CP)보다 시스플라틴＋녹차폴리페놀군(CP＋GTP)에서 유의하게 작았고, 종양조직 p53와 caspase-3 활성화가 시스플라틴군(CP)보다 시스플라틴＋녹차폴리페놀군(CP＋GTP)에서 유의하게 높았으며, 신장 GGT와 AP 활성은 시스플라틴군(CP)보다 시스플라틴＋녹차폴리페놀군(CP＋GTP)에서 유의하게 높았고, 신장 조직학적 소견에서 신세뇨관 확장과 괴사가 시스플라틴군(CP)보다 시스플라틴＋녹차폴리페놀군(CP＋GTP)에서 유의하게 낮았다. 이상의 결과 녹차폴리페놀은 EMT6 유방암 세포를 이용한 in vitro 및 in vivo 실험에서 시스플라틴의 항암작용을 증강시키면서 신장에 대한 독성 부작용은 감소시키는 효과가 있는 것으로 추측된다. 녹차폴리페놀의 시스플라틴 항암작용 증강과 신장 독성 억제 및 감소 효과는 시스플라틴에 의한 암 치료 시 화학요법제의 보조제로서 이용가치가 있는 것으로 생각되며, 항암화학요법제에 대한 보조제로의 개발을 위해서는 대규모 동물실험을 통한 효과 입증 및 부작용에 대한 실험과 임상연구가 뒷받침되어야 할 것으로 사료된다.

Cimetidine suppresses lung tumor growth in mice through proapoptosis of myeloid-derived suppressor cells

Cimetidine, a histamine type-2 receptor antagonist, is known to inhibit the growth of several tumors in human and animals, however the mechanism of action underlying this effect remains largely unknown. Here, in the mice model of 3LL lung tumor, cimetidine showed significant inhibition of tumor growth. However, an in vitro study demonstrated that cimetidine showed no effect on proliferation, survival, migration and invasion of 3LL cells. We found that cimetidine reduced CD11b+Gr-1+ myeloid derived-suppressive cell (MDSC) accumulation in spleen, blood and tumor tissue of tumor-bearing mice. In vitro coculture assay showed that cimetidine reversed MDSC-mediated T-cell suppression, and improved IFN-γ production. Further investigation demonstrated that the NO production and arginase I expression of MDSCs were reduced, and MDSCs prone to apoptosis by cimetidine treatment. However, MDSC differentiation was not affect by cimetidine. Importantly, although histamine H2 receptor was expressed in MDSC surface, histamine could not reverse the proapoptosis of cimetidine. Moreover, famotidine also did not have this capacity. We found that cimetidine could induce Fas and FasL expression in MDSC surface, and sequentially regulate caspase-dependent apoptosis pathway. Thus, these findings revealed a novel mechanism for cimetidine to inhibit tumor via modulation of MDSC apoptosis.

Antitumor Activity and Possible Mechanism of Crude Polysaccharides from &lt;i&gt;Discorea bulbifera&lt;/i&gt; L. on the Mice Bearing U14 Cervical Carcinoma

To explore the antitumor activity of crude polysaccharides of Dioscorea bulbifera L. (DBLP) and its possible mechanism, the effects of DBLP on the tumor growth in vivo, thymus and spleen weight were examined. Apoptosis of thymus, spleen and tumor tissue in tumor-bearing mice was detected by the flow cytometry. The number of CD4+ and CD8+ T-lymphocyte subsets of peripheral blood was also determined by means of FACScan flow cytometer. Our results showed that U14 cervical carcinoma growth could be inhibited, thymus weight be increased, apoptosis of thymus and spleen be decreased, and apoptosis of tumor be increased by DBLP in tumor-bearing mice. Furthermore, DBLP had the abilities to reduce the ratio of CD4+/CD8+ T-lymphocyte according to CTX group. These results indicated that DBLP could suppress the cervical carcinoma through modulating immune response of the tumor-bearing mice and inducing apoptosis of tumor tissue.

Small Heat Shock Protein as a Multifunctional Scaffold: Integrated Tumor Targeting and Caspase Imaging within a Single Cage

Protein cages have the potential to serve as biomaterials for the targeted therapeutic and imaging systems. As an effort to exploit small heat shock protein (Hsp) cages as multifunctional biomaterials, we demonstrate that chemically and genetically modified Hsp cages permeate the cells via cancer cell binding and subsequent endocytic internalization and can image caspase activity in the live cells. Moreover, we report here that these functional Hsp cages can be specifically accumulated to tumor tissues of tumor-bearing mice when administered intravenously through the lateral tail vein. These tumor-targeting properties could be explained by the prolonged in vivo circulation and enhanced permeability and retention (EPR) effect as well as the ligand-mediated binding to cancer cells. Furthermore, when combined with the caspase sensing ability, our Hsp cage allows us to monitor the therapeutic evaluation after anticancer drug treatment by imaging the caspase activity within tumors. Therefore, we demonstrate that the Hsp cages have multifunctional scaffolds amenable to genetic and chemical modifications without loss of the cagelike architecture and can be exploited as biomedical materials including drug or imaging agent carriers.

Development of cell-penetrating peptide-modified MPEG-PCL diblock copolymeric nanoparticles for systemic gene delivery

To develop a safe and efficient systemic non-viral gene vector, methoxy poly(ethylene glycol) (MPEG)/poly(ɛ-caprolactone) (PCL) diblock copolymers conjugated with a Tat analog through the ester or disulfide linkage were synthesized and their suitability as a systemic non-viral gene carrier evaluated. The physicochemical properties of the MPEG-PCL diblock copolymers were determined by GPC, 1H NMR and FT-IR spectroscopy. The particle sizes and in vitro (COS7 and S-180 cells) transfection efficiencies and cytotoxicity were evaluated. Furthermore, the luciferase activity was then determined in various tissues after intravenous injection of MPEG-PCL-SS-Tat/pCMV-Luc complex into mice bearing S-180 cells. The particle sizes of the MPEG-PCL-Tat copolymers with or without pDNA were about 40 and 60 nm, respectively. The luciferase activity in COS7 cells transfected with pCMV-Luc with MPEG-PCL-ester-Tat or MPEG-PCL-SS-Tat was higher than that with pDNA only. MPEG-PCL-SS-Tat greatly increased the transfection efficiency compared to MPEG-PCL-ester-Tat in COS7 and S-180 cells. In an in vitro cytotoxicity test MPEG-PCL-SS-Tat did not induce any remarkable cytotoxicity. In an in vivo experiment, the synthesized MPEG-PCL-SS-Tat copolymers promoted the delivery and expression of pDNA into tumor tissue in tumor-bearing mice. In conclusion, this vector might be applicable as a tumor-targeting non-viral systemic gene carrier in the clinical setting.

Local Radiation Therapy Inhibits Tumor Growth through the Generation of Tumor-Specific CTL: Its Potentiation by Combination with Th1 Cell Therapy

Radiation therapy is one of the primary treatment modalities for cancer along with chemotherapy and surgical therapy. The main mechanism of the tumor reduction after irradiation has been considered to be damage to the tumor DNA. However, we found that tumor-specific CTL, which were induced in the draining lymph nodes (DLN) and tumor tissue of tumor-bearing mice, play a crucial role in the inhibition of tumor growth by radiation. Indeed, the therapeutic effect of irradiation was almost completely abolished in tumor-bearing mice by depleting CD8(+) T cells through anti-CD8 monoclonal antibody administration. In mice whose DLN were surgically ablated or genetically defective (Aly/Aly mice), the generation of tetramer(+) tumor-specific CTL at the tumor site was greatly reduced in parallel with the attenuation of the radiation-induced therapeutic effect against the tumor. This indicates that DLN are essential for the activation and accumulation of radiation-induced CTL, which are essential for inhibition of the tumor. A combined therapy of local radiation with Th1 cell therapy augmented the generation of tumor-specific CTL at the tumor site and induced a complete regression of the tumor, although radiation therapy alone did not exhibit such a pronounced therapeutic effect. Thus, we conclude that the combination treatment of local radiation therapy and Th1 cell therapy is a rational strategy to augment antitumor activity mediated by tumor-specific CTL.

Tumor Targeting of Functionalized Quantum Dot−Liposome Hybrids by Intravenous Administration

A strategy to target functionalized quantum dot-liposome (f-QD-L) hybrid vesicles in the solid tumor tissue of tumor-bearing mice is explored. Functionalized polyethylene glycol (PEG)-lipid coated QD (f-QD) were encapsulated into the aqueous core of 100 nm cationic (DOPC:Chol: DOTAP); sterically stabilized, fluid-phase (DOPC:Chol:DSPE-PEG2000); and sterically stabilized, gel-phase (DSPC:Chol:DSPE-PEG2000) liposome vesicles. Double tracking of f-QD-L in blood was performed at different time points after intravenous administration in B16F10 melanoma tumor-bearing C57BL6 mice. Cholesteryl [-1-14C] oleate lipids probed the vesicle membrane were followed by liquid scintillation counting while QD were determined independently by elemental (Cd2+) analysis using inductively coupled plasma mass spectrometry (ICP-MS). Rapid blood clearance was observed following intravenous administration of the cationic hybrid vesicles, while incorporation of PEG at the surface of zwitterionic vesicles dramatically prolonged their blood circulation half-life after systemic administration. The "rigid" PEGylated f-QD-L (DSPC:Chol:DSPE-PEG2000) hybrid vesicles led to rapid tumor accumulation of peak values (approximately 5% of injected dose per gram tissue) of QD compared to long-circulating f-QD that accumulated in the tumor tissue at longer time points. More interestingly, this hybrid vesicle tumor retention persisted for at least 24 h. For almost all types of systems, a preferential cadmium uptake by liver and spleen was obtained. Overall, f-QD-L hybrid vesicles offer great potential for tumor imaging applications due to their rapid accumulation and prolonged retention within the tumor. Furthermore, f-QD-L offer many opportunities for the development of combinatory therapeutic and imaging (theranostic) modalities by incorporating both drug molecules and QD within the different compartments of a single vesicle.

Antitumor efficacy of cisplatin-loaded glycol chitosan nanoparticles in tumor-bearing mice

To make a tumor targeting nano-sized drug delivery system, biocompatible and biodegradable glycol chitosan ( M w = 250 kDa) was modified with hydrophobic cholanic acid. The resulting hydrophobically modified glycol chitosans (HGCs) that formed nano-sized self-aggregates in an aqueous medium were investigated as an anticancer drug carrier in cancer treatment. Insoluble anticancer drug, cisplatin (CDDP), was easily encapsulated into the hydrophobic cores of HGC nanoparticles by a dialysis method, wherein the drug loading efficiency was about 80%. The CCDP-encapsulated HGC (CDDP-HGC) nanoparticles were well-dispersed in aqueous media and they formed a nanoparticles structure with a mean diameter about 300–500 nm. As a nano-sized drug carrier, the CDDP-HGC nanoparticles released the drug in a sustained manner for a week and they were also less cytotoxic than was free CDDP, probably because of sustained release of CDDP from the HGC nanoparticles. The tumor targeting ability of CDDP-HGC nanoparticles was confirmed by in vivo live animal imaging with near-infrared fluorescence Cy5.5-labeled CDDP-HGC nanoparticles. It was observed that CDDP-HGC nanoparticles were successfully accumulated by tumor tissues in tumor-bearing mice, because of the prolonged circulation and enhanced permeability and retention (EPR) effect of CDDP-HGC nanoparticles in tumor-bearing mice. As expected, the CDDP-HGC nanoparticles showed higher antitumor efficacy and lower toxicity compared to free CDDP, as shown by changes in tumor volumes, body weights, and survival rates, as well as by immunohistological TUNEL assay data. Collectively, the present results indicate that HGC nanoparticles are a promising carrier for the anticancer drug CDDP.

Tumor-Associated CD8+ T Cell Tolerance Induced by Bone Marrow-Derived Immature Myeloid Cells

T cell tolerance is a critical element of tumor escape. However, the mechanism of tumor-associated T cell tolerance remains unresolved. Using an experimental system utilizing the adoptive transfer of transgenic T cells into naive recipients, we found that the population of Gr-1+ immature myeloid cells (ImC) from tumor-bearing mice was able to induce CD8+ T cell tolerance. These ImC accumulate in large numbers in spleens, lymph nodes, and tumor tissues of tumor-bearing mice and are comprised of precursors of myeloid cells. Neither ImC from control mice nor progeny of tumor-derived ImC, including tumor-derived CD11c+ dendritic cells, were able to render T cells nonresponsive. ImC are able to take up soluble protein in vivo, process it, and present antigenic epitopes on their surface and induce Ag-specific T cell anergy. Thus, this is a first demonstration that in tumor-bearing mice CD8+ T cell tolerance is induced primarily by ImC that may have direct implications for cancer immunotherapy.

A Polymeric Nanoparticle Consisting of mPEG-PLA-Toco and PLMA-COONa as a Drug Carrier: Improvements in Cellular Uptake and Biodistribution

To evaluate a new polymeric nanoparticulate drug delivery formulation that consists of two components: i) an amphiphilic diblock copolymer having tocopherol moiety at the end of the hydrophobic block in which the hydrophobic tocopherol moiety increases stability of hydrophobic core of the nanoparticle in aqueous medium; and ii) a biodegradable copolyester having carboxylate end group that is capable of forming ionic complex with positively charged compounds such as doxorubicin. A doxourubicin-loaded polymeric nanoparticle (Dox-PNP) was prepared by solvent evaporation method. The entrapment efficiency, size distribution, and in vitro release profile at various pH conditions were characterized. In vitro cellular uptake was investigated by confocal microscopy, flow cytometry, and MTT assay using drug-sensitive and drug-resistant cell lines. Pharmacokinetics and biodistribution were evaluated in rats and tumor-bearing mice. Doxorubicin (Dox) was efficiently loaded into the PNP (higher than 95% of entrapment efficiency), and the diameter of Dox-PNP was in the range 20-25 nm with a narrow size distribution. In Vitro study showed that Dox-PNP exhibited higher cellular uptake into both human breast cancer cell (MCF-7) and human uterine cancer cell (MES-SA) than free doxorubicin solution (Free-Dox), especially into drug-resistant cells (MCF-7/ADR and MES-SA/Dx-5). In pharmacokinetics and tissue distribution study, the bioavailability of Dox-PNP calculated from the area under the blood concentration-time curve (AUC) was 69.8 times higher than that of Free-Dox in rats, and Dox-PNP exhibited 2 times higher bioavailability in tumor tissue of tumor-bearing mice. Dox-PNP exhibited enhanced cellular uptake of the drug. In the cytotoxic activity study, this improved cellular uptake was proved to be more advantageous in drug-resistant cell. Dox-PNP exhibited much higher bioavailability in blood plasma and more drug accumulation in tumor tissue than conventional doxorubicin formulation. The results of this study suggest that the PNP system is an advantageous carrier for drug delivery.

Investigation on the effects of soluble programmed death-1 (sPD-1) enhancing anti-tumor immune response.

By using semi-quantitative RT-PCR method, it was found that PD-L1 mRNA but not PD-L2 mRNA was expressed in H22 hepatoma cells and both PD-L1 and PD-L2 mRNAs were expressed in tumor tissues of tumor-bearing mice and upregulated as compared with muscle tissues in normal mice and H22 hepatoma cells. PD-L1 and PD-L2 were also expressed on the surface of the activated T cells. The soluble recombinant sPD-1 expressed from the constructed eukaryotic expression vector could enhance the lysis of tumor cells by lymphocytes stimulated specifically with antigen. The expresssion of sPD-1 by local gene therapy on the inoculation site of H22 hepatoma cells could inhibit the growth of tumor. The results of this study indicate that expression of soluble receptor of negative costimulatory molecules could reduce the inhibitory effect on T cells in tumor microenvironment and enhance the cytotoxicity of T cells on tumor cells. This possibly provides a new method of improving efficacy of tumor gene therapy.

Doxorubicin Encapsulated in Long-Circulating Thermosensitive Liposomes

AbstractDoxorubicin (DXR) was encapsulated in long-circulating, thermosensitive liposomes (TSL, 180-200 nm in mean diameter), prepared from dipalmitoyl phosphatidyl choline (DPPC)/distearoyl phosphatidyl choline (DSPC) (9:1, m/m) and either 3 mol% of amphipathic polyethylene glycol (PEG) with 1000 in average molecular weight or 6 mol% of ganglioside GMI (GMI), with 95-98% entrapping efficiency by the pH gradient method. 57% or 45% of the entrapped DXR was released from PEG/DPPC/DSPC or GM1/DPPC/DSPC liposomes, respectively, by incubation with 20% serum at 42°C for 5 min. Inclusion of PEG or GM1 endowed TSL with prolonged circulation ability, resulting in increased blood levels of liposomes and decreased reticuloendothelial system (RES) uptake over 6 hours after injection. Concomitantly, high DXR level in blood was kept for long time.Accumulation of DXR into tumor tissue of tumor-bearing mice (mouse colon carcinoma 26) by local hyperthermia after injection of DXR-long-circulating TSL was 2 times or 7 times...

Enhanced delivery of doxorubicin to tumor by long-circulating thermosensitive liposomes and local hyperthermia

Doxorubicin (DXR) was encapsulated in long-circulating, thermosensitive liposomes (180–200 nm), prepared from dipalmitoylphosphatidylcholine (DPPC)/distearoylphosphatidylcholine (DSPC) (9:1 (m/m)) and 6 mol% of ganglioside G M1 (G M1), with 95–98% entrapping efficiency by the pH-gradient method. 45% of the entrapped DXR was released from these G M1/DPPC/DSPC liposomes by incubation at 42°C for 5 min in 20% serum or saline (this degree of release was lower than that of hydrophilic drugs such as cisplatin, due to the basic and amphiphilic nature of DXR). Inclusion of G M1 (6 mol%) endowed DPPC/DSPC liposomes with prolonged circulation ability, resulting in increased blood levels of liposomes and decreased reticuloendothelial system uptake over 6 h after injection. Concomitantly, DXR levels in blood remained high for long time. Accumulation of DXR into tumor tissue of tumor-bearing mice (mouse colon carcinoma 26) by local hyperthermia after injection of DXR loaded, long-circulating, thermosensitive (DXR-G M1/DPPC/DSPC) liposomes was 2.5-times or 6-times higher than that after treatment with DXR-DPPC/DSPC liposomes or free DXR in combination with hyperthermia, respectively. Furthermore, the treatment with DXR-G M1/DPPC/DSPC liposomes and hyperthermia resulted in effective tumor-growth retardation and increased survival time. Our results indicate that the combination of drug-loaded, long-circulating, thermosensitive liposomes with local hyperthermia at the tumor site could be clinically useful for delivering a wide range of chemotherapeutic agents in the treatment of solid tumors.