Chitosan Modification-Enhanced Silencing Effect of Ad5-shPDGF-D Vector in Breast Cancer Cell Line MDA-MB-231.

BACKGROUND: Gene therapeutics are being developed to treat metastatic breast tumors, which are mostly resistant to conventional therapies. Targeting platelet-derived growth factor-D (PDGF-D) is a viable approach because it is known to play roles in angiogenesis and tumor growth. The success of gene therapy is largely dependent on delivery vectors, but both viral and nonviral delivery vectors have their disadvantages. Evolving hybrid vectors are being used to overcome those disadvantages. OBJECTIVES: In this study, we aimed to prepare a recombinant adenovirus type-5 (Ad5)/chitosan hybrid vector to deliver shPDGF-D in a breast cancer cell line by the noncovalent coating of the Ad5 surface with chitosan, a natural polymer. METHODS: The Ad5/chitosan hybrid vector was prepared by the noncovalent coating of the Ad5 surface with different molecular weights (low and high) and different amounts of chitosan (12.5, 25, and 50 µg), and the effect of silencing PDGF-D was investigated in the MDA-MB-231 cell line. RESULTS: In vitro characterization studies showed that the noncovalent chitosan coating increased the size of the Ad5 particle and changed the surface charge from -16.53 mV to slightly neutral. In vitro cell culture studies also showed that the addition of chitosan with both low (73.61%) and high (65.86%) molecular weight increased the PDGF-D silencing efficiency of the Ad5 vector (42.44%) at 48 hours. While low-molecular-weight chitosan had faster effects, high-molecular-weight chitosan provided a more sustained effect in PDGF-D silencing. CONCLUSION: The results indicate that noncovalent chitosan modification may improve the therapeutic effects of the Ad5 vector, offering the potential for further in vitro and in vivo experiments.

Combination therapy with chitosan/siRNA nanoplexes targeting PDGF-D and PDGFR-ß reveals anticancer effect in breast cancer.

BACKGROUND: Platelet derived growth factors (PDGF)-D and the expression of its receptor increase in neoplastic progression of cancer. Co-silencing of growth factor and receptor can be suggested as an important strategy for effective cancer therapy. In the present study, we hypothesized that suppression of PDGF-D signaling pathway with small interfering RNAs (siRNAs) targeting both PDGF-D and PDGF receptor (PDGFR)-ß is a promising strategy for anticancer therapy. METHODS: Chitosan nanoplexes containing dual and single siRNA were prepared at different weight ratios and controlled by gel retardation assay. Characterization, cellular uptake, gene silencing and invasion studies were performed. The effect of nanoplexes on breast tumor growth, PDGF expression and apoptosis was investigated. RESULTS: We have shown that downregulation of PDGF-D and PDGFR-ß with chitosan/siRNA nanoplex formulations reduced proliferation and invasion in breast cancer cells. In the in vivo breast tumor model, it was determined that the intratumoral administration of chitosan/siPDGF-D/siPDGFR-ß nanoplexes markedly decreased the tumor volume and PDGF-D and PDGFR-ß mRNA and protein expression levels and increased apoptosis. CONCLUSIONS: According to the results obtained, we evaluated the effect of PDGF-D and PDGFR-ß on breast tumor development and showed that RNAi-mediated inhibition of this pathway formulated with chitosan nanoplexes can be considered as a new breast cancer therapy strategy.

Effects of Chitosan Nanoparticles with Long Synthetic siRNAs Targeting VEGF in Triple-Negative Breast Cancer Cells

Abstract Vascular endothelial growth factor (VEGF) is an essential angiogenic factor in breast cancer development and metastasis. Small interfering RNAs (siRNAs) can specifically silence genes via the RNA interference pathway, therefore were investigated as cancer therapeutics. In this study, we investigated the effects of siRNAs longer than 30 base pairs (bp) loaded into chitosan nanoparticles in triple-negative breast cancer cells, compared with conventional siRNAs. 35 bp long synthetic siRNAs inhibited VEGF gene expression by 51.2% and increased apoptosis level by 1.75-fold in MDA-MB-231 cell lines. Furthermore, blank and siRNA-loaded chitosan nanoparticles induced expression of IFN-γ in breast cancer cells. These results suggest that long synthetic siRNAs can be as effective as conventional siRNAs, when introduced into cells with chitosan nanoparticles

Investigation of therapeutic effects in the wound healing of chitosan/pGM-CSF complexes

Abstract Granulocyte macrophage colony-stimulating factor (GM-CSF) has been shown to promote the growth, proliferation, and migration of endothelial and keratinocyte cells. Chitosan has been widely used as a biopolymer in wound-healing studies. The aim of this study was to investigate the in vitro proliferative effects of chitosan/pGM-CSF complexes as well as the therapeutic role of the complexes in an in vivo rat wound model. The effect of complexes on cell proliferation and migration was examined. Wounds were made in Wistar-albino rats, and examined histopathologically. The cell proliferation and migration were increased weight ratio- and time-dependently in HaCaT and NIH-3T3 cell lines. Wound healing was significantly accelerated in rats treated with the complexes. These results showed that the delivery of pGM-CSF using chitosan complexes could play an accelerating role in the cell proliferation, migration, and wound-healing process.

Modulation of the dual-faced effects of miR-141 with chitosan/miR-141 nanoplexes in breast cancer cells.

BACKGROUND: miR-141, known as a tumor suppressive microRNA, is downregulated in breast cancer. However, recent contrasting studies report that it also acts as oncogene when it is upregulated. The present study aimed to investigate whether miR-141 is a tumor suppressor or oncogenic when it reaches normal levels in chitosan/miR-141 nanoplexes. METHODS: Chitosan nanoplexes were prepared using simple complexation method. Nanoplexes were characterized by a gel retardation assay and zeta potential and particle size measurements. To determine the expression level of miR-141, a quantitative real-time polymerase chain reaction was performed. The effects of miR-141 mimics were investigated with respect to angiogenesis by vascular endothelial growth factor (VEGF), epithelial-mesenchymal transition (EMT) by E-cadherin, metastasis by Igfbp-4 and Tinagl1 enzyme-linked immunosorbent assays, invasion by an invasion chamber, and apoptosis by Annexin V. RESULTS: The miR-141 expression levels of MDA-MB-231 and MDA-MB-435 cells by administration of chitosan/mimic miR-141 nanoplexes reached endogenous miR-141 levels of a non-tumorigenic epithelial breast cell line, MCF-10A. According to our results, metastasis, VEGF, EMT and invasion in breast cancer cells were diminished, whereas apoptosis increased by 1.5- and 2.4-fold in breast cancer cell lines as a result of the miR-141 mimics. CONCLUSIONS: In conclusion, we have demonstrated that administration of miR-141 mimics at the determined doses to breast cancer cells revealed a tumor suppressor effect, and not the oncogenic face. The delivery of miR-141 by chitosan nanoplexes presents a promising approach for the suppression of breast cancer.

The effectiveness of chitosan-mediated silencing of PDGF-B and PDGFR-ß in the mesangial proliferative glomerulonephritis therapy.

Platelet-derived growth factor-B (PDGF-B) is a growth factor that plays an important role in the progression of mesangial proliferative glomerulonephritis (MsPGN). PDGF-B may contribute to mesangioproliferative changes and is overexpressed in MsPGN. Recently, small interfering RNAs (siRNAs) have been widely used for gene silencing effects in experimental models of renal diseases. Nanoparticle-based therapeutics are preferred for reasons such as increasing therapeutic efficacy and reducing toxic effects caused by high doses. The distribution of nanoparticles to the kidney is a significant advantage in siRNA delivery. The aim of this study was to investigate the efficacy of chitosan/siRNA nanoplexes in silencing of PDGF-B and PDGFR-ß genes in kidney and to decrease mesangial cell proliferation and matrix accumulation in MsPGN model induced by anti-Thy-1.1 antibody. The therapeutic effects of chitosan/siPDGF-B + siPDGFR-ß nanoplexes in glomerulonephritic rats were studied by molecular, biochemical, and histopathologic evaluations. Chitosan/siPDGF-B + siPDGFR-ß nanoplexes markedly reduced PDGF-B and PDGFR-ß mRNA and protein expressions in experimental MsPGN model. Histopathologic examination results showed that the silencing of PDGF-B and its receptor PDGFR-ß led to reduction in mesangial cell proliferation and matrix accumulation. The use of chitosan/siPDGF-B + siPDGFR-ß nanoplexes for silencing the PDGF-B pathway in MsPGN can be considered as a new effective therapeutic strategy.

Inhibition of Glomerular Mesangial Cell Proliferation by siPDGF-B- and siPDGFR-ß-Containing Chitosan Nanoplexes.

Mesangioproliferative glomerulonephritis is a disease that has a high incidence in humans. In this disease, the proliferation of glomerular mesangial cells and the production of extracellular matrix are important. In recent years, the RNAi technology has been widely used in the treatment of various diseases due to its capability to inhibit the gene expression with high specificity and targeting. The objective of this study was to decrease mesangial cell proliferation by knocking down PDGF-B and its receptor, PDGFR-ß. To be able to use small interfering RNAs (siRNAs) in the treatment of this disease successfully, it is necessary to develop appropriate delivery systems. Chitosan, which is a biopolymer, is used as a siRNA delivery system in kidney drug targeting. In order to deliver siRNA molecules targeted at PDGF-B and PDGFR-ß, chitosan/siRNA nanoplexes were prepared. The in vitro characterization, transfection studies, and knockdown efficiencies were studied in immortalized and primary rat mesangial cells. In addition, the effects of chitosan nanoplexes on mesangial cell proliferation and migration were investigated. After in vitro transfection, the PDGF-B and PDGFR-ß gene silencing efficiencies of PDGF-B and PDGFR-ß targeting siRNA-containing chitosan nanoplexes were 74 and 71% in immortalized rat mesangial cells and 66 and 62% in primary rat mesangial cells, respectively. siPDGF-B- and siPDGFR-ß-containing nanoplexes indicated a significant decrease in mesangial cell migration and proliferation. These results suggested that mesangial cell proliferation may be inhibited by silencing of the PDGF-B signaling pathway. Gene silencing approaches with chitosan-based gene delivery systems have promise for the efficient treatment of renal disease.

In Vitro Dose Studies on Chitosan Nanoplexes for microRNA Delivery in Breast Cancer Cells.

Changes in microRNA (miRNA) expression levels that play important roles in regulation lead to many pathological events such as cancer. The miR-200 family is an important target in cancer therapy. The aim of this study is to equilibrate endogenous levels between cancer and noncancerous cells to prevent serious side effects of miR-200c- and miR-141-like metastatic colonization. For the first time, the characterization of miR-200c and miR-141 cluster containing chitosan nanoplexes was shown, and the optimization of miRNA expression levels by conducting dose studies in breast cancer cell lines was made. The mean diameter of chitosan/miR-141 and chitosan/miR-200c nanoplexes ranged from 296 to 355 nm and from 294 to 380 nm depending on the N/P ratio, respectively. The surface charge of nanoplexes was positive with zeta potential of +12 to +26 mV. While naked miRNA was degraded after 0 min in a 10% serum-containing medium, chitosan/miRNA nanoplexes were protected for 72 h. During the in vitro cellular uptake study, nanoplexes were observed to be accumulating in the cytoplasm or nucleus. After using different doses for miR-200c, the determined doses are 750, 100, and 750 ng in the MCF-7, MDA-MB-231, and MDA-MB-435 cell lines, respectively. Doses were determined as 100 ng for MDA-MB-231 and 150 ng for MDA-MB-435 to reach endogenous miR-141 levels of MCF-10A. Our results suggest that chitosan nanoplexes for miR-200c and miR-141 are an efficient delivery system in terms of formulation and transfection. As a conclusion, dose studies are important to provide effective treatment with miRNAs.

Development and characterization of vancomycin-loaded levan-based microparticular system for drug delivery.

Encapsulation of vancomycin (VANCO) into biodegradable levan microparticles was achieved using a simple preparation technique. Microparticles were prepared by using levan polysaccharide produced by a halophilic bacterium Halomonas smyrnensis AAD6T. To optimize efficiency of encapsulation process by precipitation method, three parameters were studied: drug and polymer concentrations and preparation rotating speed. The particles were characterized in vitro. The size of levan microparticles was changed between 0.404 µm and 1.276 µm. The surface charge was detected between +4.1 mV and +6.5 mV. The highest drug encapsulation capacity of the system was 74.7% and was depending on the polymer concentration. In dissolution studies, initial burst effect around 10-20% from all the formulations was observed and then the release was slowed down and continued at a constant level. In vitro antibiotic release from the microparticles was controlled with the drug carrier system and release fit to Higuchi kinetic model. All the released samples collected at different time intervals during dissolution studies have exhibited intrinsic bactericidal activity against Bacillus subtilis ATCC 6633. WST-1 cell proliferation and viability studies showed that VANCO-loaded levan microparticles at concentrations between 100 µg/mL and 1000 µg/mL were nontoxic to L929 cells. As conclusion, levan microparticulate system could be a potential carrier of antibiotic drugs such as VANCO.

Generation of stable cell line by using chitosan as gene delivery system.

Establishing stable cell lines are useful tools to study the function of various genes and silence or induce the expression of a gene of interest. Nonviral gene transfer is generally preferred to generate stable cell lines in the manufacturing of recombinant proteins. In this study, we aimed to establish stable recombinant HEK-293 cell lines by transfection of chitosan complexes preparing with pDNA which contain LacZ and GFP genes. Chitosan which is a cationic polymer was used as gene delivery system. Stable HEK-293 cell lines were established by transfection of cells with complexes which were prepared with chitosan and pVitro-2 plasmid vector that contains neomycin drug resistance gene, beta gal and GFP genes. The transfection efficiency was shown with GFP expression in the cells using fluorescence microscopy. Beta gal protein expression in stable cells was examined by beta-galactosidase assay as enzymatically and X-gal staining method as histochemically. Full complexation was shown in the above of 1/1 ratio in the chitosan/pDNA complexes. The highest beta-galactosidase activity was obtained with transfection of chitosan complexes. Beta gal gene expression was 15.17 ng/ml in the stable cells generated by chitosan complexes. In addition, intensive blue color was observed depending on beta gal protein expression in the stable cell line with X-gal staining. We established a stable HEK-293 cell line that can be used for recombinant protein production or gene expression studies by transfecting the gene of interest.

Differences between Solution and Membrane Forms of Chitosan on the In Vitro Activity of Fibroblasts.

BACKGROUND: Chitosan, a linear polysaccharide, has been recently used in biomedical applications. In vitro studies have demonstrated its effect on cellular growth and its stimulatory action on cellular layer formation. AIMS: The present study aims to compare the proliferative effects of chitosan in two forms, membranous and solution forms, on Swiss 3T3 mouse embryonic fibroblasts. STUDY DESIGN: In vitro study. METHODS: Three experimental groups were formed: cells were cultured in a normal medium without chitosan (Control Group); cells were cultured either in a medium containing 2.0% chitosan in membranous form (Membrane Group) or chitosan solution at a concentration of 2.0% (Solution Group). Two different methods were used in the experiments: cells cultured on the medium containing chitosan in solution or membranous forms (method 1); and chitosan solution or membranous forms were added into the medium containing previously cultured cells (method 2). RESULTS: Scanning electron microscopic investigations of the experimental groups revealed cells with well-defined cellular projections, intact cellular membranes and tight intercellular junctions. They were especially prominent in the membrane group of method 1 and in the membrane and solution groups of method 2. Mouse monoclonal anti-collagen 1 primary antibody was used to indicate collagen synthesis. Prominent collagen synthesis was detected in the membrane groups on the 10(th) day of culture for both methods. Bromodeoxyuridine (BrdU) and MTT assays were performed in order to assess cellular proliferation and viability, respectively. BrdU labelling tests indicated a higher proliferation index in the membrane group of method 1 on the 5(th) and 10(th) days. For the second method, the membranous form on the 10(th) day and solution form on the 5(th) day were the most effective groups in terms of cellular proliferation. MTT results reflected a high cellular viability in method 1 on the 5(th) day of treatment with the membranous form, whereas cellular viability was highest in the solution form of method 2 on the 5(th) day. CONCLUSION: The membranous form of chitosan induced a significant proliferative effect and increased the ratio of cell-to-cell junctions of Swiss 3T3 mouse embryonic fibroblasts. Conveniently, the solution form also resulted in enhanced cell proliferation and viability compared to the control group. As the solution form is easy to prepare and apply to cells compared to the membrane form, the application of Chitosan directly to media appears to be a convenient alternative for tissue engineering approaches.

Synthesis of pro-apoptotic indapamide derivatives as anticancer agents.

4-Chloro-3-({[(substitutedamino)carbonothioyl]amino}sulfonyl)-N-(2-methyl-2,3-dihydro-1H-indole-1-yl)benzamide (1-20) and 4-chloro-3-({[3-(substituted)-4-oxo-1,3-thiazolidine-2-ylidene]amino}sulfonyl)-N-(2-methyl-2,3-dihydro-1H-indole-1-yl)benzamide derivatives (21-31) were synthesized from 4-chloro-N-(2-methyl-2,3-dihydroindol-1-yl)-3-sulfamoylbenzamide (indapamide). 4-Chloro-3-({[(4-chlorophenyl) amino) carbonothioyl]amino}sulfonyl)-N-(2-methyl-2,3-dihydro-1H-indole-1-yl)benzamide 12 demonstrated the highest proapoptotic activity among all synthesized compounds on melanoma cell lines MDA-MB-435 with 3.7% growth inhibition at the concentration of 10 µM. Compound 12 (SGK 266) was evaluated in vitro using the MTT colorimetric method against melanoma cancer cell line MDA-MB435 growth inhibition for different doses and exhibited anticancer activity with IC50 values of 85-95 µM against melanoma cancer cell line MDA-MB435. In addition, this compound was investigated as inhibitors of four physiologically relevant human carbonic anhydrase isoforms, hCA I, II, IX and XII. The compund inhibited these enzymes with IC50 values ranging between 0.72 and 1.60 µM.

The enhancement of gene silencing efficiency with chitosan-coated liposome formulations of siRNAs targeting HIF-1α and VEGF.

RNA interference (RNAi) holds considerable promise as a novel therapeutic strategy in the silencing of disease-causing genes. The development of effective delivery systems is important for the use of small interfering RNA (siRNA) as therapy. In the present study, we investigated the effect on breast cancer cell lines and the co-delivery of liposomes containing siHIF1-α and siVEGF. In order to achieve the co-delivery of siHIF1-α and siVEGF and to obtain lower cytotoxicity, higher transfection and silencing efficiency, in this study, we used chitosan-coated liposomal formulation as the siRNA delivery system. The obtained particle size and zeta potential values show that the chitosan coating process is an effective parameter for particle size and the zeta potential of liposomes. The liposome formulations loaded with siHIF1-α and siVEGF showed good stability and protected siRNA from serum degradation after 24-h of incubation. The expression level of VEGF mRNA was markedly suppressed in MCF-7 and MDA-MB435 cells transfected with chitosan-coated liposomes containing HIF1-α and VEGF siRNA, respectively (95% and 94%). In vitro co-delivery of siVEGF and siHIF1-α using chitosan-coated liposome significantly inhibited VEGF (89%) and the HIF1-α (62%) protein expression when compared to other liposome formulations in the MDA-MB435 cell. The co-delivery of siVEGF and siHIF1-α was greatly enhanced in the vitro gene silencing efficiency. In addition, chitosan-coated liposomes showed 96% cell viability. Considering the role of VEGF and HIF1-α in breast cancer, siRNA-based therapies with chitosan coated liposomes may have some promises in cancer therapy.

Comparison of VEGF gene silencing efficiencies of chitosan and protamine complexes containing shRNA.

VEGF is an angiogenic factor promoting the proliferation and migration of endothelial cells. Inhibition of VEGF by RNAi mechanism is one of the novel and the most important strategies in antiangiogenesis therapy. In this study, the tumor silencing efficiency of ternary complexes after addition of protamine to chitosan complexes containing VEGF targeting shRNA was investigated. Besides chitosan, protamine is an effective gene delivery material. Binary and ternary complexes consisting of chitosan, protamine, and shRNA were prepared to target VEGF, their morphology, size, and zeta potential of the complexes being measured. The average size of the complexes was between 173 and 284 nm and zeta potential was between +10 and 16 mV. In the ternary complexes, size decreased as the chitosan ratio increased; however, its molecular weight had no effect on the size of complexes. HeLa, HEK293, and MCF-7 cell lines were used for in vitro transfection. VEGF was assayed by ELISA. A higher silencing effect was obtained using ternary complexes. Transgene expression was increased by adding protamine to chitosan complexes. Gene inhibition values in cell lines followed the rank HEK293>HeLa>MCF-7. The addition of protamine to the chitosan/shRNA (VEGF) complexes increased the knockdown of VEGF genes in the cell lines, and no cytotoxicity was found after the complexes had been incorporated into the cells.

Investigation of the therapeutic efficacy of codelivery of psiRNA-vascular endothelial growth factor and pIL-4 into chitosan nanoparticles in the breast tumor model.

Angiogenesis has been known to increase tumor growth and for its metastatic potential in human tumors. Vascular endothelial growth factor (VEGF) plays an important role in tumor angiogenesis and is a promising therapeutic target for breast cancer. VEGF is an essential target for RNAi-based gene therapy of breast cancer. Interleukin-4 (IL-4) may act as an anti-angiogenic molecule that inhibits tumor growth and migration in rats. The purpose of the present study was to improve therapeutic efficacy in breast cancer with the codelivery of siRNA-expressing plasmid targeting VEGF and IL-4-expressing plasmid encapsulating into chitosan nanoparticles (NPs). The codelivery of psiVEGF and pIL-4 plasmids greatly enhanced in vitro and in vivo gene-silencing efficiency. For the in vitro study, when psiVEGF and pIL-4 into chitosan NPs were combined (81%), the gene-silencing effect was higher than psiVEGF and pIL-4 NPs alone. The in vivo study breast tumor model demonstrated that the administration of coencapsulation of psiVEGF and pIL-4 into chitosan NPs caused an additive effect on breast tumor growth inhibition (97%), compared with containing NPs psiVEGF or pIL-4 alone. These results indicate that chitosan NPs can be effectively used for the codelivery of pIL-4 and siVEGF-expressing plasmid in a combination therapy against breast cancer.

Synthesis, cytotoxicity, and pro-apoptosis activity of etodolac hydrazide derivatives as anticancer agents.

Etodolac hydrazide and a novel series of etodolac hydrazide-hydrazones 3-15 and etodolac 4-thiazolidinones 16-26 were synthesized in this study. The structures of the new compounds were determined by spectral (FT-IR, (1)H NMR, (13)C NMR, HREI-MS) methods. Some selected compounds were determined at one dose toward the full panel of 60 human cancer cell lines by the National Cancer Institute (NCI, Bethesda, USA). 2-(1,8-Diethyl-1,3,4,9-tetrahydropyrano[3,4-b]indole-1-yl)acetic acid[(4-chlorophenyl)methylene]hydrazide 9 demonstrated the most marked effect on the prostate cancer cell line PC-3, with 58.24% growth inhibition at 10(-5) M (10 µM). Using the MTT colorimetric method, compound 9 was evaluated in vitro against the prostate cell line PC-3 and the rat fibroblast cell line L-929, for cell viability and growth inhibition at different doses. Compound 9 exhibited anticancer activity with an IC(50) value of 54 µM (22.842 µg/mL) against the PC-3 cells and did not display any cytotoxicity toward the L-929 rat fibroblasts, compared to etodolac. In addition, this compound was evaluated for caspase-3 and Bcl-2 activation in the apoptosis pathway, which plays a key role in the treatment of cancer.

The development of ternary nanoplexes for efficient small interfering RNA delivery.

Targeted posttranscriptional gene silencing by RNA interference (RNAi) has garnered considerable interest as an attractive new class of drugs for several diseases, such as cancer. Chitosan and protamine are commonly used as a vehicle to deliver and protect small interfering RNA (siRNA), but the strong interaction still remains to be modulated for efficient siRNA uptake and silencing. Therefore, in this study, ternary nanoplexes containing chitosan and protamine were designed to substantially enhance the siRNA efficiency. Binary and ternary nanoplexes were prepared at different the ratios of moles of the amine groups of cationic polymers to those of the phosphate ones of siRNA (N/P) ratios and characterized in terms of size, zeta potential, morphology and serum stability. The silencing efficiencies and cytotoxicities of prepared nanoplexes were evaluated by enzyme-linked immunosorbent assay (ELISA) (for human vascular endothelial growth factor; hVEGF) and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assays, respectively. The mean diameter of ternary nanoplexes ranged from 151 to 282 nm, depending on the weight ratio between polymers and siRNA. The gene silencing effect after transfection with ternary nanoplexes (chitosan/siRNA/protamine 83%) was significantly higher than that with binary nanoplexes (chitosan/siRNA 71% and protamine/siRNA 74%). Ternary nanoplexes showed the highest cellular uptake ability when compared with binary nanoplexes. Ternary nanoplexes did not induce substantial cytotoxicity. Serum stability and the lack of cytotoxicity of the nanoplexes provided advantages over other gene silencing studies. These results suggest ternary nanoplexes have the potential to be an effective siRNA carrier to study the gene silencing effect.

Local delivery of chitosan/VEGF siRNA nanoplexes reduces angiogenesis and growth of breast cancer in vivo.

Vascular endothelial growth factor (VEGF) is the important angiogenic factor associated with tumor growth and metastasis in a wide variety of solid tumors. The aim of this study is to investigate the tumor suppressive effect of chitosan/small interfering RNA (siRNA)-VEGF nanoplexes in the rat breast cancer model. Chitosan/siRNA nanoplexes (siVEGF-A, siVEGFR-1, siVEGFR-2) and NRP-1 were prepared in a 15 to1 ratio and injected (intratumorally) into the breast-tumor-bearing Sprague-Dawley rats. Tumor volumes were measured during 21 days. To investigate the effect of chitosan/siRNA nanoplexes on VEGF expression in tumors, VEGF was analyzed with immunohistochemistry and western blotting. The mRNA levels of VEGF in tumor samples were determined with real-time PCR (RT-PCR). After siRNA treatment, a marked reduction in tumor volumes was measured in complex-injected rats (97%). Free siRNA injection showed lower tumor inhibition. Reduction of VEGF protein was also shown with western blotting and immunohistochemistry. Similar results were obtained with RT-PCR also. These results indicate that the chitosan/siRNA targeting to VEGF nanoplexes have a remarkably suppressive effect on VEGF expression and tumor volume in breast cancer model of rats.