Ji-Young Shin

Magnetic nanoparticles: an update of application for drug delivery and possible toxic effects

Magnetic nanoparticles (MNPs) represent a subclass within the overall category of nanomaterials and are widely used in many applications, particularly in the biomedical sciences such as targeted delivery of drugs or genes, in magnetic resonance imaging, and in hyperthermia (treating tumors with heat). Although the potential benefits of MNPs are considerable, there is a distinct need to identify any potential toxicity associated with these MNPs. The potential of MNPs in drug delivery stems from the intrinsic properties of the magnetic core combined with their drug loading capability and the biomedical properties of MNPs generated by different surface coatings. These surface modifications alter the particokinetics and toxicity of MNPs by changing protein–MNP or cell–MNP interactions. This review contains current advances in MNPs for drug delivery and their possible organ toxicities associated with disturbance in body iron homeostasis. The importance of protein–MNP interactions and various safety considerations relating to MNP exposure are also addressed.

Poly(ester amine)-mediated, Aerosol-delivered Akt1 Small Interfering RNA Suppresses Lung Tumorigenesis

RATIONALE The low efficiency of conventional therapies in achieving long-term survival of patients with lung cancer calls for the development of novel therapeutic options. Recent advances in aerosol-mediated gene delivery have provided the possibility of an alternative for the safe and effective treatment of lung cancer. OBJECTIVES To demonstrate the feasibility and emphasize the importance of noninvasive aerosol delivery of Akt1 small interfering RNA (siRNA) as an effective and selective option for lung cancer treatment. METHODS Nanosized poly(ester amine) polymer was synthesized and used as a gene carrier. An aerosol of poly(ester amine)/Akt1 siRNA complex was delivered into K-ras(LA1) and urethane-induced lung cancer models through a nose-only inhalation system. The effects of Akt1 siRNA on lung cancer progression and Akt-related signals were evaluated. MEASUREMENTS AND MAIN RESULTS The aerosol-delivered Akt1 siRNA suppressed lung tumor progression significantly through inhibiting Akt-related signals and cell cycle. CONCLUSIONS The use of poly(ester amine) serves as an effective carrier, and aerosol delivery of Akt1 siRNA may be a promising approach for lung cancer treatment and prevention.

High Dietary Inorganic Phosphate Increases Lung Tumorigenesis and Alters Akt Signaling

RATIONALE Phosphate (Pi) is an essential nutrient to living organisms. Recent surveys indicate that the intake of Pi has increased steadily. Our previous studies have indicated that elevated Pi activates the Akt signaling pathway. An increased knowledge of the response of lung cancer tissue to high dietary Pi may provide an important link between diet and lung tumorigenesis. OBJECTIVES The current study was performed to elucidate the potential effects of high dietary Pi on lung cancer development. METHODS Experiments were performed on 5-week-old male K-ras(LA1) lung cancer model mice and 6-week-old male urethane-induced lung cancer model mice. Mice were fed a diet containing 0.5% Pi (normal Pi) and 1.0% Pi (high Pi) for 4 weeks. At the end of the experiment, all mice were killed. Lung cancer development was evaluated by diverse methods. MEASUREMENT AND MAIN RESULTS A diet high in Pi increased lung tumor progression and growth compared with normal diet. High dietary Pi increased the sodium-dependent inorganic phosphate transporter-2b protein levels in the lungs. High dietary consumption of Pi stimulated pulmonary Akt activity while suppressing the protein levels of tumor suppressor phosphatase and tensin homolog deleted on chromosome 10 as well as Akt binding partner carboxyl-terminal modulator protein, resulting in facilitated cap-dependent protein translation. In addition, high dietary Pi significantly stimulated cell proliferation in the lungs of K-ras(LA1) mice. CONCLUSIONS Our results showed that high dietary Pi promoted tumorigenesis and altered Akt signaling, thus suggesting that careful regulation of dietary Pi may be critical for lung cancer prevention as well as treatment.

Galectin-3 Facilitates Cell Motility in Gastric Cancer by Up-Regulating Protease-Activated Receptor-1(PAR-1) and Matrix Metalloproteinase-1(MMP-1)

Background Galectin-3 is known to regulate cancer metastasis. However, the underlying mechanism has not been defined. Through the DNA microarray studies after galectin-3 silencing, we demonstrated here that galectin-3 plays a key role in up-regulating the expressions of protease-activated receptor-1(PAR-1) and matrix metalloproteinase-1(MMP-1) PAR-1 thereby promoting gastric cancer metastasis. Methodology/Principal Findings We examined the expression levels of Galectin-3, PAR-1, and MMP-1 in gastric cancer patient tissues and also the effects of silencing these proteins with specific siRNAs and of over-expressing them using specific lenti-viral constructs. We also employed zebrafish embryo model for analysis of in vivo gastric cancer cell invasion. These studies demonstrated that: a) galectin-3 silencing decreases the expression of PAR-1. b) galectin-3 over-expression increases cell migration and invasion and this increase can be reversed by PAR-1 silencing, indicating that galectin-3 increases cell migration and invasion via PAR-1 up-regulation. c) galectin-3 directly interacts with AP-1 transcriptional factor, and this complex binds to PAR-1 promoter and drives PAR-1 transcription. d) galectin-3 also amplifies phospho-paxillin, a PAR-1 downstream target, by increasing MMP-1 expression. MMP-1 silencing blocks phospho-paxillin amplification and cell invasion caused by galectin-3 over-expression. e) Silencing of either galectin-3, PAR-1 or MMP-1 significantly reduced cell migration into the vessels in zebrafish embryo model. f) Galectin-3, PAR-1, and MMP-1 are highly expressed and co-localized in malignant tissues from gastric cancer patients. Conclusions/Significance Galectin-3 plays the key role of activating cell surface receptor through production of protease and boosts gastric cancer metastasis. Galectin-3 has the potential to serve as a useful pharmacological target for prevention of gastric cancer metastasis.

Chitosan-graft-spermine as a gene carrier in vitro and in vivo

Chitosan has been proposed as a non-viral gene carrier because of its biodegradable and biocompatible cationic polymeric properties. However, the transfection efficiency of chitosan-DNA complexes is still too low for clinical trials. To improve transfection efficiency, we prepared a chitosan-graft-spermine (CHI-g-SPE) copolymer by an imine reaction between periodate-oxidized chitosan and spermine. The CHI-g-SPE copolymer was complexed with plasmid DNA in various copolymer-DNA weight ratios, and the complexes were characterized. The CHI-g-SPE copolymer showed good DNA binding ability and high protection of DNA from nuclease attack. The CHI-g-SPE/DNA complexes had well-formed spherical shapes and a nanoscale size with homogenous size distribution. The CHI-g-SPE copolymer had low cytotoxicity and CHI-g-SPE/DNA complexes showed transfection efficiency that was enhanced over that of chitosan-DNA. Furthermore, aerosol delivery of CHI-g-SPE/GFP complexes showed higher GFP expression compared with chitosan/GFP complexes, without toxicity. Our results indicate that the CHI-g-SPE copolymer has potential as a gene carrier.

Toxicity and clearance of intratracheally administered multiwalled carbon nanotubes from murine lung.

Carbon nanotubes (CNT) are known to have widespread industrial applications; however, several reports indicated that these compounds may be associated with adverse effects in humans. In this study, multiwalled carbon nanotubes were administered to murine lungs intratracheally to determine whether acute and chronic pulmonary toxicity occurred. In particular, pristine multiwalled carbon nanotubes (PMWCNT) and acid-treated multiwalled carbon nanotubes (TMWCNT) were used in this study. In broncheoalveolar lavage fluid (BALF) cell analysis, PMWCNT induced more severe acute inflammatory cell recruitment than TMWCNT. Histopathologically, both PMWCNT and TMWCNT induced multifocal inflammatory granulomas in a dose-dependent manner. The observed granulomas were reversible, with TMWCNT-induced granulomas diminishing faster than PMWCNT-induced granulomas. Although the area of granuloma reduced with time, hyperplasia and dysplastic characteristics such as mitotic figures, anisokaryosis, and anisocytosis were still observed. These findings demonstrate that MWCNT induces granulomatous inflammation, and the duration and pattern of inflammation seem to vary depending upon the types of MWCNT to which mice are exposed. Therefore, toxicity studies on various types of CNT are needed as the responsiveness to these compounds differs.

Chondroitin sulfate extracted from the Styela clava tunic suppresses TNF-α-induced expression of inflammatory factors, VCAM-1 and iNOS by blocking Akt/NF-κB signal in JB6 cells

Inflammatory mediators are known to play a key role in tumorigenesis, therefore, it is a promising strategy to inhibit the inflammation for cancer prevention and/or treatment. Current study was performed to investigate the effects of chondroitin sulfate (CS) extracted from Styela clava tunic on TNF-alpha-induced inflammation and to elucidate the mechanism of CS on the regulation of inflammatory factors in JB6 cells. Our results showed that CS inhibited TNF-alpha-induced NF-kappaB activation and subsequent vascular cell adhesion molecule 1 and inducible nitric oxide synthase expressions by blocking Akt signals in JB6 cells. Our results suggest that CS may be developed as an effective anti-inflammatory agent in the future.

Accelerated gene transfer through a polysorbitol-based transporter mechanism.

Here we report an accelerated gene transfer through a polysorbitol-based osmotically active transporter (PSOAT) that shows several surprising results through interesting mechanisms. The nano-sized and well-complexed PSOAT/DNA particles are less toxic, stable at serum and show no aggregation after lyophilization due to their polysorbitol backbone. The transfection is remarkably accelerated both in vitro and in vivo, presumably due to a transporter mechanism of PSOAT in spite of possibility of reduction of transfection by many hydroxyl groups in the transporter. PSOAT possesses a transporter mechanism owing to its polysorbitol backbone, which enhances cellular uptake by exerting polysorbitol transporter activity, thus accelerates gene transfer to cells because transfection ability of PSOAT is drastically reduced in the presence of a cyclooxygenase (COX)-2-specific inhibitor, which we have reported as an inhibitor of the transporter to cells. Moreover, the gene expression is found to be enhanced by hyperosmotic activity and buffering capacity due to polysorbitol and polyethylenimine backbone of PSOAT, respectively. The polysorbitol in PSOAT having polyvalency showed more efficiency in accelerating gene transfer capability than monovalent sorbitol. The above interesting mechanisms display PSOAT as a remarkably potential system to deliver therapeutic (small interfering RNA) and diagnostic agents for effective treatment of cancer.

Silencing of galectin-3 changes the gene expression and augments the sensitivity of gastric cancer cells to chemotherapeutic agents.

Galectin‐3 is known to modulate cell proliferation and apoptosis and is highly expressed in human cancers, but its function in gastric cancer is still controversial. Here, we examined the role of galectin‐3 in gastric cancer cells by silencing it with synthetic double‐stranded siRNA. After silencing of galectin‐3, cell numbers decreased and cell shape changed. Galectin‐3 siRNA treatment also induced G1 arrest. DNA microarray analysis was used to assess changes in gene expression following galectin‐3 silencing. We found that silencing of galectin‐3 caused changes in gene expression. RT‐PCR and real‐time PCR were utilized for validation of the changes found in microarray studies. Western blot analysis confirmed changes in the expression of proteins of interest: cyclin D1, survivin, XIAP, XAF, PUMA, and GADD45α. Generally, it tended to increase the expression of several pro‐apoptotic genes, and to decrease the expression of cell cycle progressive genes. We also confirmed that changes in the expression of these genes were caused by galectin‐3 overexpression. Finally, we demonstrated that silencing of galectin‐3 enhanced apoptosis induction with chemotherapeutic agents by further reducing the expression of anti‐apoptotic and/or cell survival molecules such as survivin, cyclin D1, and XIAP, and increasing the expression of pro‐apoptotic XAF‐1. We conclude that galectin‐3 is involved in cancer progression and malignancy by modulating the expression of several relevant genes, and inhibition of galectin‐3 may be an approach to improve chemotherapy of gastric cancers. (Cancer Sci 2009)

Synergistic effect of ERK inhibition on tetrandrine-induced apoptosis in A549 human lung carcinoma cells

Tetrandrine (TET), a bis-benzylisoquinoline alkaloid from the root of Stephania tetrandra, is known to have anti-tumor activity in various malignant neoplasms. However, the precise mechanism by which TET inhibits tumor cell growth remains to be elucidated. The present studies were performed to characterize the potential effects of TET on phosphoinositide 3-kinase/Akt and extracellular signal-regulated kinase (ERK) pathways since these signaling pathways are known to be responsible for cell growth and survival. TET suppressed cell proliferation and induced apoptosis in A549 human lung carcinoma cells. TET treatment resulted in a down-regulation of Akt and ERK phosphorylation in both time-/concentration-dependent manners. The inhibition of ERK using PD98059 synergistically enhanced the TET-induced apoptosis of A549 cells whereas the inhibition of Akt using LY294002 had a less significant effect. Taken together, our results suggest that TET: i) selectively inhibits the proliferation of lung cancer cells by blocking Akt activation and ii) increases apoptosis by inhibiting ERK. The treatment of lung cancers with TET may enhance the efficacy of chemotherapy and radiotherapy and increase the apoptotic potential of lung cancer cells.