Cancer gene therapy by IL-12 gene delivery using liposomal bubbles and tumoral ultrasound exposure

Interleukin-12 (IL-12) gene therapy is expected to be effective against cancers because it primes the immune system for cancer cells. In this therapy, it is important to induce IL-12 gene expression in the tumor tissue. Sonoporation is an attractive technique for developing non-invasive and non-viral gene delivery systems, but simple sonoporation using only ultrasound is not an effective cancer gene therapy because of the low efficiency of gene delivery. We addressed this problem by combining ultrasound and novel ultrasound-sensitive liposomes (Bubble liposomes) which contain the ultrasound imaging gas perfluoropropane. Our previous work showed that this is an effective gene delivery system, and that Bubble liposome collapse (cavitation) is induced by ultrasound exposure. In this study, we assessed the utility of this system in cancer gene therapy using IL-12 corded plasmid DNA. The combination of Bubble liposomes and ultrasound dramatically suppressed tumor growth. This therapeutic effect was T-cell dependent, requiring mainly CD8(+) T lymphocytes in the effector phase, as confirmed by a mouse in vivo depletion assay. In addition, migration of CD8(+) T cells was observed in the mice, indicating that the combination of Bubble liposomes and ultrasound is a good non-viral vector system in IL-12 cancer gene therapy.

Effective gene delivery with liposomal bubbles and ultrasound as novel non-viral system

We developed the novel liposomal bubbles (Bubble liposomes) containing ultrasound imaging gas, perfluoropropane. Bubble liposomes were made of pegylated liposomes and were smaller than conventional microbubbles. Bubble liposomes also had a function as imaging agents in cardiosonography. In addition, Bubble liposomes could deliver plasmid DNA into various types of cells in vitro without cytotoxicity by the combination of ultrasound. In vivo gene delivery, Bubble liposomes could deliver plasmid DNA into mouse femoral artery by the transdermally exposure of ultrasound. This transfection efficiency was more effectively than lipofection method. Interestingly, the gene expression was only observed at the site of ultrasound exposure. Therefore, we concluded that Bubble liposomes could be good tools to establish tissue-specific gene delivery system as well as ultrasound imaging agents.

Delivery of siRNA into the cytoplasm by liposomal bubbles and ultrasound

Small interfering RNA (siRNA) is expected to be a novel therapeutic tool, however, its utilization has been limited by inefficient delivery systems. Recently, we have developed novel polyethyleneglycol modified liposomes (Bubble liposomes; BL) entrapping an ultrasound (US) imaging gas, which can work as a gene delivery tool with US exposure. In this study, we investigated whether the BL were suitable for the delivery of siRNA. BL efficiently delivered siRNA with only 10 s of exposure to US in vitro. Specific gene silencing effects could be achieved well even in the presence of serum or with the disruption of endocytosis. We suggest that siRNA is directly introduced into the cytoplasm by the BL and US and the mechanism enables effective transfection within a short time and in the presence of high serum. Transfection of siRNA into the tibialis muscles with BL and US was also performed. The gene-silencing effect could be sustained for more than 3 weeks. Thus, BL could be a useful siRNA delivery tool in vitro and in vivo.

Injectable growth/differentiation factor-5-recombinant human collagen composite induces endochondral ossification via Sry-related HMG box 9 (Sox9)expression and angiogenesis in murine calvariae

BACKGROUND AND OBJECTIVE

The types of collagens available today as biomaterials are purified from animal tissues. A major growing concern, however, is their safety, since there are risks of viral and prion contamination and of unknown and potentially zoonotic infectious diseases. The present study aimed to assess, using immunohistochemistry, the effects of recombinant human growth/differentiation factor-5 (rhGDF-5) combined with recombinant human collagen I (rhCI) on bone formation in murine calvariae.

MATERIAL AND METHODS

Composite rhGDF-5-rhCI or rhCI alone was injected subcutaneously into murine calvariae. After 3, 7 or 14 days, tissues were examined radiologically, histologically and immunohistochemically. The production of vascular endothelial growth factor (VEGF) by primary osteoblasts, periosteal cells and connective tissue fibroblasts isolated enzymatically from neonatal murine calvariae was also assessed.

RESULTS

A protrusion was observed on the calvariae at the site injected with rhGDF-5/rhCI composite. Its mineral density was shown to be different from that of the existing bone by two-dimensional microcomputed tomography. Type II collagen-positive staining was restricted to newly formed tissues. Thus, the newly formed tissues seemed to be bone- and cartilage-like tissues. A number of vessels with positively stained cells for Von Willebrand factor were detected in the newly formed tissues. The rhGDF-5 enhanced VEGF production in cultured connective tissue fibroblasts. Sry-related HMG box 9 (Sox9)-positive cells were detected in the hypertrophic periosteum, and penetrated into the newly formed tissues.

CONCLUSIONS

These results suggest that rhCI seems to allow the release of rhGDF-5 and that rhGDF-5-rhCI composite induces endochondral ossification via Sox9 expression and angiogenesis in murine calvariae.

[Development of site specific gene delivery system with sonoporation]

In gene therapy, it is important to develop an effective and safe gene delivery system. Especially, from the viewpoint of reducing side effects, gene delivery into a specific site is essential. We previously, developed liposomal bubbles (Bubble liposomes) containing perfluoropropane. Bubble liposomes were useful as ultrasound enhanced gene delivery tools in vitro and in vivo. In this review, we introduced the characteristics of Bubble liposomes as ultrasound imaging agents and ultrasound enhanced gene delivery tools. Bubble liposomes worked as ultrasound imaging agents in cardiosonography. In addition, their combination with ultrasound exposure was able to deliver plasmid DNA in the femoral artery. The gene expression was only observed at the site of ultrasound exposure. Moreover, the gene delivery by Bubble liposomes and ultrasound exposure was more efficient than that by conventional lipofection method using Lipofectamine 2000. Therefore, it was suggested that Bubble liposomes might be a new class of tools for site specific gene delivery.

Effective gene delivery with novel liposomal bubbles and ultrasonic destruction technology

From the viewpoint of safety, non-viral vector systems represent an attractive gene delivery system for gene therapy. However, the transfection efficiency of non-viral vectors in vivo is generally very low. Previously, it was reported that microbubbles, utilized as imaging agents for diagnostic echocardiography, could promote gene delivery into cells when combined with ultrasound exposure. We therefore developed novel liposomal bubbles (Bubble liposomes) containing the lipid nanobubbles of perfluoropropane which is used as ultrasound imaging agent. These Bubble liposomes were smaller in diameter than conventional microbubbles and induced cavitation upon exposure to ultrasound. These results suggested that cavitation of these Bubble liposomes could be an efficient approach for delivering plasmid DNA into cells. In addition, in in vivo gene delivery, the combination of Bubble liposomes and ultrasound provided more effective gene delivery than conventional lipofection methods, further suggesting that Bubble liposomes could be effective as a non-viral vector system in in vivo gene delivery. In this review, we discuss the characteristics of Bubble liposomes and their potential utility as a gene delivery tool in vitro and in vivo.

Tumor specific ultrasound enhanced gene transfer in vivo with novel liposomal bubbles

Bubble liposomes (liposomes which entrap an ultrasound imaging gas) may constitute a unique system for delivering various molecules efficiently into mammalian cells in vitro. In this study, Bubble liposomes were compared with cationic lipid (CL)-DNA complexes as potential gene delivery carriers into tumor in vivo. The delivery of genes by Bubble liposomes depended on the intensity of the applied ultrasound. Transfection efficiency plateaued at 0.7 W/cm(2) ultrasound intensity. Bubble liposomes efficiently transferred genes into cultured cells even when the cells were exposed to ultrasound for only 1 s. In addition, Bubble liposomes could introduce the luciferase gene more effectively than CL-DNA complexes into mouse ascites tumor cells and solid tumor tissue. We conclude that the combination of Bubble liposomes and ultrasound is a minimally-invasive and tumor specific gene transfer method in vivo.

[Drug and gene delivery by "bubble liposomes" and ultrasound]

Gene therapy has a potentiality for treatment of cancer and diseases from genomic defects. It is important to select a vector which has good potency in terms of gene transduction efficiency, and is safe and easy to apply. Many researchers have attempted to develop an effective gene delivery carrier. Recently, it was reported that microbubbles, which are ultrasound (US) contrast agents, improved the transfection efficiency by cavitation with US exposure. However, microbubbles had problems with stability and targeting ability. To solve these problems, we focused on liposomes that had many advantages such as being stable and safe in vivo and easily modifying targeting ligand. We succeeded in preparing the liposomes ("Bubble liposomes" (BLs)) entrapping perfluoropropane gas which was utilized for contrast enhancement in ultrasonography. In this study, we assessed the feasibility of BLs as gene delivery carrier utilized cavitation by US exposure. BLs could deliver plasmid DNA to various cell types in vitro by combining with US without cytotoxicity. To evaluate the ability of BLs to in vivo gene delivery, we attempted to deliver plasmid DNA into the femoral artery. The gene expression at this artery treated with BLs and US combination was higher than with US only, BLs without US or Lipofectamine 2000. This result suggested that Bubble liposomes could quickly deliver plasmid DNA into the artery even under conditions of short contact time between BLs and the endothelial cells and the existence of the bloodstream and serum. These results suggested that BLs might be a non-invasive and effective carrier for gene delivery.

Involvement of phosphatidylinositol-3-kinase and ERK pathways in the production of TGF-beta1 by macrophages treated with liposomes composed of phosphatidylserine

We explored the involvement of phosphatidylinositol 3-kinase (PI3K) and ERK pathways in the production of TGF-beta1 by macrophages treated with liposomes composed of phosphatidylserine (PS-liposomes). PS-liposomes activated Akt, downstream of the PI3K signal cascade, and ERK which led to the expression of TGF-beta1. PI3K inhibitors, LY294002 and wortmannin, inhibited the activation of Akt and ERK following the treatment with PS-liposomes. These inhibitors also suppressed the production of TGF-beta1. Furthermore, PS-liposomes activated macrophages to induce TGF-beta1 expression through PS-specific receptors. These findings suggested that a PI3K-ERK signaling pathway via the PS-receptor is intimately involved in the production of TGF-beta1 which regulates macrophage functions.

Gene silencing by the tRNA maturase tRNase ZL under the direction of small-guide RNA

We have been developing a unique system for the downregulation of a gene expression through cutting a specific mRNA by the long form of tRNA 3'-processing endoribonuclease (tRNase Z(L)) under the direction of small-guide RNA (sgRNA). However, the efficacy of this system and the involvement of tRNase Z(L) in the living cells were not clear. Here we show, by targeting the exogenous luciferase gene, that the efficacy of the sgRNA/tRNase Z(L) method can become comparable to that of the RNA interference technology and that the gene silencing is owing to tRNase Z(L) directed by sgRNA not owing to a simple antisense effect. We also show that tRNase Z(L) together with sgRNA can downregulate expression of the endogenous human genes Bcl-2 and glycogen synthase kinase-3beta by degrading their mRNAs in cell culture. Furthermore, we demonstrate that a gene expression in the livers of postnatal mice can be inhibited by an only seven-nucleotide sgRNA. These data suggest that sgRNA might be utilized as therapeutic agents to treat diseases such as cancers and AIDS.

Gene delivery by combination of novel liposomal bubbles with perfluoropropane and ultrasound

Microbubbles and ultrasound have recently been investigated with a view to improving the transfection efficiency of non-viral gene delivery systems. However, microbubbles are unstable and their targeting ability is insufficient for clinical use. To circumvent these problems, we developed novel polyethyleneglycol (PEG) modified liposomes (Bubble liposomes) containing perfluoropropane, which is an ultrasound imaging gas. Here, we used ultrasound to induce cavitation in Bubble liposomes and then investigated their ability to deliver genes in vitro and in vivo. Bubble liposomes could deliver plasmid DNA to many cell types without cytotoxicity. Additionally, in vivo gene delivery, Bubble liposomes were more effective delivery into femoral artery than lipofection method. Thus, Bubble liposomes might be efficient and novel non-viral tools for gene delivery.

Simvastatin decreases IL-6 and IL-8 production in epithelial cells

Many cardiovascular studies have suggested that 3-hydroxy-3-methylglutaryl co-enzyme A reductase inhibitors (statins) have anti-inflammatory effects independent of cholesterol lowering. As a chronic inflammatory disease, periodontitis shares some mechanisms with atherosclerosis. Since oral epithelial cells participate importantly in periodontal inflammation, we measured simvastatin effects on interleukin-6 and interleukin-8 production by cultured human epithelial cell line (KB cells) in response to interleukin-1alpha. Simvastatin decreased production, an effect reversed by adding mevalonate or geranylgeranyl pyrophosphate, but not farnesyl pyrophosphate. Simvastatin was found to reduce NF-kappaB and AP-1 promoter activity in KB cells. Dominant-negative Rac1 severely inhibited interleukin-1alpha-induced NF-kappaB and AP-1 promoter activity. Our results may indicate an anti-inflammatory effect of simvastatin on human oral epithelial cells, apparently involving Rac1 GTPase inhibition.

Methyl-introduced A-ring analogues of 1alpha,25-dihydroxyvitamin D3: synthesis and biological evaluation

The hormonally-active metabolite of vitamin D, 1alpha,25-dihydroxyvitamin D3 (1), has a wide variety of biological activities, which makes it a promising therapeutic agent for the treatment of cancer, psoriasis and osteoporosis. Insights into the structure-activity relationships of the A-ring of 1 are needed to assist the development of more potent and selective analogues, as well as to define the molecular mode of action. All possible A-ring stereoisomers of 2-methyl-1,25-dihydroxyvitamin D3 and 2,2-dimethyl-1,25-dihydroxyvitamin D3, which differ in stereochemistry at the C1-, C2- and C3-positions, were designed and efficiently synthesized by employing the convergent method. Biological evaluation of the analogues, in terms of the vitamin D receptor-binding affinity and HL-60 cell differentiation-inducing activity, as well as the transcriptional potency in ROS 17/2.8 cells, revealed the importance of substituents at the C2-position in certain orientations.

Induction of cancer cell-specific apoptosis by folate-labeled cationic liposomes

We have previously reported that cationic liposomes themselves can induce apoptosis in macrophages and lymphocytes. In this paper, we attempted the cancer cell-specific delivery of cationic liposomes and the induction of apoptosis utilizing this characteristic. Cationic liposomes composed of stearylamine (SA-liposomes) induced apoptosis in human nasopharyngeal epidermoid carcinoma cells (KB cells) overexpressing the folate receptor and human fibroblasts (WI-38 cells) with no folate receptor, without showing selectivity. To recruit liposomes to cancer cells and induce apoptosis, we focused on the folate receptor and prepared folic acid-labeled liposomes using polyethyleneglycol (PEG) (folate-PEG-liposomes). Folate-PEG-liposomes showed selectivity and induced apoptosis in KB cells, but not WI-38 cells. The apoptosis occurred in a dose-dependent manner. Furthermore, folate-PEG-liposomes appear to associate with KB cells via the folate receptor, whereas SA-liposomes may associate with cells through electrostatic interactions. To confirm the contribution of the folate receptor to apoptosis of KB cells induced by folate-PEG-liposomes, the effect of folic acid on the apoptosis was examined. The addition of free folic acid drastically suppressed the apoptosis of KB cells and the percentage of cells with hypodiploid nuclei returned to the control level. Taken together, cationic liposomes labeled with folate bound to KB cells via folate receptors and, interestingly, the cationic liposomes themselves could cause apoptosis in cancer cells.

Gene transfer to corneal epithelium and keratocytes mediated by ultrasound with microbubbles

PURPOSE

The cornea is an ideal organ for evaluating gene transfer because it can be treated noninvasively and monitored easily. The present study was performed to investigate the practical efficacy and safety of ultrasound (US) plus microbubble (MB)-mediated gene transfer to cornea.

METHODS

Cultured rabbit corneal epithelial (RC-1) cells were incubated in 24-well dishes with plasmid DNA having a green fluorescent protein (GFP) gene under a cytomegalovirus promoter. The cells were exposed to US under different intensities (1 MHz; power, 0.5 approximately 2 W/cm2; duration, 15-120 seconds; duty cycle, 20%-100%). The effect of simultaneous stimulation with MBs was also examined. Gene transfer was quantified by counting the number of GFP-positive cells under microscopy. Furthermore, in vivo gene transfer was examined by GFP plasmid injection into rabbit cornea and US exposure with MBs.

RESULTS

In the in vitro study, DNA exposure alone could not transfer gene into cultured RC-1 cells; US enhanced gene transfer slightly. Coexposure with MBs significantly increased gene transfer efficiency. In the in vivo study, DNA injection alone could transfer the gene to a limited degree, but plasmid injection plus US with MBs strongly increased gene transfer efficiency without apparent tissue damage, and gene transfer was achieved two dimensionally.

CONCLUSIONS

US with MBs greatly increases gene transfer to in vivo and in vitro corneal cells. This noninvasive gene transfer method may be a useful tool for clinical gene therapy.

p21Cip-1/SDI-1/WAF-1 expression via the mitogen-activated protein kinase signaling pathway in insulin-induced chondrogenic differentiation of ATDC5 cells

The embryonal carcinoma-derived cell line, ATDC5, differentiates into chondrocytes in response to insulin or insulin-like growth factor-I stimulation. In this study, we investigated the roles of mitogen-activated protein (MAP) kinases in insulin-induced chondrogenic differentiation of ATDC5 cells. Insulin-induced accumulation of glycosaminoglycan and expression of chondrogenic differentiation markers, type II collagen, type X collagen, and aggrecan mRNA were inhibited by the MEK1/2 inhibitor (U0126) and the p38 MAP kinase inhibitor (SB203580). Conversely, the JNK inhibitor (SP600125) enhanced the synthesis of glycosaminoglycan and expression of chondrogenic differentiation markers. Insulin-induced phosphorylation of ERK1/2 and JNK but not that of p38 MAP kinase. We have previously clarified that the induction of the cyclin-dependent kinase inhibitor, p21(Cip-1/SDI-1/WAF-1), is essential for chondrogenic differentiation of ATDC5 cells. To assess the relationship between the induction of p21 and MAP kinase activity, we investigated the effect of these inhibitors on insulin-induced p21 expression in ATDC5 cells. Insulin-induced accumulation of p21 mRNA and protein was inhibited by the addition of U0126 and SB203580. In contrast, SP600125 enhanced it. Inhibitory effects of U0126 or stimulatory effects of SP600125 on insulin-induced chondrogenic differentiation were observed when these inhibitors exist in the early phase of differentiation, suggesting that MEK/ERK and JNK act on early phase differentiation. SB202580, however, is necessary not only for early phase but also for late phase differentiation, indicating that p38 MAP kinase stimulates differentiation by acting during the entire period of cultivation. These results for the first time demonstrate that up-regulation of p21 expression by ERK1/2 and p38 MAP kinase is required for chondrogenesis, and that JNK acts as a suppressor of chondrogenesis by down-regulating p21 expression.

Control of steroid, heme, and carcinogen metabolism by nuclear pregnane X receptor and constitutive androstane receptor

Through a multiplex promoter spanning 218 kb, the phase II UDP-glucuronosyltransferase 1A (UGT1) gene encodes at least eight differently regulated mRNAs whose protein products function as the principal means to eliminate a vast array of steroids, heme metabolites, environmental toxins, and drugs. The orphan nuclear receptors pregnane X receptor (PXR) and constitutive androstane receptor (CAR) were originally identified as sensors able to respond to numerous environmentally derived foreign compounds (xenobiotics) to promote detoxification by phase I cytochrome P450 genes. In this report, we show that both receptors can induce specific UGT1A isoforms including those involved in estrogen, thyroxin, bilirubin, and carcinogen metabolism. Transgenic mice expressing a constitutively active form of human PXR show markedly increased UGT activity toward steroid, heme, and carcinogens, enhanced bilirubin clearance, as well as massively increased steroid clearance. The ability of PXR and constitutive androstane receptor and their ligands to transduce both the phase I and phase II adaptive hepatic response defines a unique transcriptional interface that bridges the ingestion and metabolism of environmental compounds to body physiology.

Lipid-mediated delivery of oligonucleotide to pulmonary endothelium

Pulmonary endothelium plays an important role in the maintenance of normal pulmonary physiology and its dysfunction is involved in a number of pulmonary diseases. Correction of endothelial dysfunction via antisense oligodeoxyonucleotides (ODN) is dependent on the development of a delivery vehicle that can efficiently deliver the ODN to pulmonary endothelium with minimal toxicity. To this end, we have developed a lipidic vector (LPD) that is composed of 1,2-dioleoyl-3-trimethylammonium-propane (DOTAP) liposomes, protamine, and ODN. This formulation is highly efficient in delivering ODN to the lung via the vascular route. The efficiency of delivery is a function of lipid composition and of the charge ratio between lipid and ODN. Immunofluorescence staining of BrdU-labeled ODN suggested efficient accumulation of ODN in the alveolar capillary region. Transmission electron microscopy of immunogold localization of BrdU-labeled ODN confirmed that pulmonary endothelial cells were indeed targeted by the vector. Furthermore, this formulation is associated with minimal proinflammatory cytokine response and other hematologic toxicities when the ODN lack a potent unmethylated CpG motif. Pretreatment of mice with LPD containing an ODN against intercellular adhesion molecule-1 (ICAM-1) significantly decreased ICAM-1 expression in the lung following LPS challenge. These results provide a basis for lipid-mediated delivery of ODN for the treatment of pulmonary diseases.