4-O-methylascochlorin activates autophagy by activating AMPK and suppressing c-Myc in glioblastoma.

A prior study identified that 4-O-methylascochlorin (MAC), a methylated derivative of ascochlorin (ASC) from the fungus Ascochyta viciae, activates autophagy in leukemia cells by suppressing c-Myc phosphorylation. However, the effects of MAC on autophagy in other cancer cells remain unknown. In the present study, we demonstrated that MAC activated autophagy in human glioblastoma. MAC increased expression of autophagy-related proteins, such as LC3-II and Beclin-1. Moreover, MAC stimulated AMP-activated protein kinase (AMPK) phosphorylation and suppressed phosphorylation of the mTOR, p70S6K, and 4EBP1. The well-known AMPK activator metformin increased LC3-II levels, which were augmented by MAC cotreatment. AMPK knockdown decreased LC3-II levels and inhibited MAC activation of autophagy. Furthermore, MAC suppression of c-Myc expression activated autophagy. Treatment with the c-MYC inhibitor, 10058-FA, induced autophagy, as did c-Myc small interfering RNA knockdown. These effects were augmented by MAC cotreatment. Taken together, these findings indicated that MAC induces autophagy in human glioblastoma by activating AMPK signaling and inhibiting c-Myc protein expression in human glioblastoma.

Upregulation of AMPK by 4-O-methylascochlorin promotes autophagy via the HIF-1α expression.

4-O-methylascochlorin (MAC) is a derivative of ascochlorin, a prenyl-phenol compound antibiotic isolated from the fungus Ascochyta viciae. MAC induces caspase/poly (ADP-ribose) polymerase-mediated apoptosis in leukemia cells. However, the effects of MAC on autophagy in cancer cells and the underlying molecular mechanisms remain unknown. Here, we show that MAC induces autophagy in lung cancer cells. MAC significantly induced the expression of autophagy marker proteins including LC3-II, Beclin1, and ATG7. MAC promoted AMP-activated protein kinase (AMPK) phosphorylation and inhibited the phosphorylation of mammalian target of rapamycin (mTOR) and its downstream signalling proteins P70S6K and 4EBP1. The AMPK activator AICAR upregulated LC3-II expression through the AMPK/mTOR pathway similar to the effects of MAC. MAC-induced LC3-II protein expression was slightly reduced in AMPK siRNA transfected cells. MAC upregulated hypoxia-inducible factor-1α (HIF-1α) and BNIP3, which are HIF-1α-dependent autophagic proteins. Treatment with CoCl2 , which mimics hypoxia, induced autophagy similar to the effect of MAC. The HIF-1α inhibitor YC-1 and HIF-1α siRNA inhibited the MAC-induced upregulation of LC3-II and BNIP3. These results suggest that MAC induces autophagy via the AMPK/mTOR signalling pathway and by upregulating HIF-1α and BNIP3 protein expression in lung cancer cells.

Tumor suppressor PDCD4 inhibits NF-κB-dependent transcription in human glioblastoma cells by direct interaction with p65.

PDCD4 is a tumor suppressor induced by apoptotic stimuli that regulates both translation and transcription. Previously, we showed that overexpression of PDCD4 leads to decreased anchorage-independent growth in glioblastoma (GBM)-derived cell lines and decreased tumor growth in a GBM xenograft model. In inflammatory cells, PDCD4 stimulates tumor necrosis factor-induced activation of the transcription factor NF-κB, an oncogenic driver in many cancer sites. However, the effect of PDCD4 on NF-κB transcriptional activity in most cancers including GBM is still unknown. We studied the effect of PDCD4 on NF-κB-dependent transcriptional activity in GBM by stably overexpressing PDCD4 in U251 and LN229 cells. Stable PDCD4 expression inhibits NF-κB transcriptional activation measured by a luciferase reporter. The molecular mechanism by which PDCD4 inhibits NF-κB transcriptional activation does not involve inhibited expression of NF-κB p65 or p50 proteins. PDCD4 does not inhibit pathways upstream of NF-κB including the activation of IKKα and IKKß kinases or degradation of IκBα, events needed for nuclear transport of p65 and p50. PDCD4 overexpression does inhibit localization of p65 but not p50 in the nucleus. PDCD4 protein interacts preferentially with p65 protein as shown by co-immunoprecipitation and confocal imaging. PDCD4 overexpression inhibits the mRNA expression of two NF-κB target genes in a p65-dependent manner. These results suggest that PDCD4 can significantly inhibit NF-κB activity in GBM cells by a mechanism that involves direct or indirect protein-protein interaction independent of the expected mRNA-selective translational inhibition. These findings offer novel opportunities for NF-κB-targeted interventions to prevent or treat cancer.

Cancer-associated splicing variant of tumor suppressor AIMP2/p38: pathological implication in tumorigenesis.

Although ARS-interacting multifunctional protein 2 (AIMP2, also named as MSC p38) was first found as a component for a macromolecular tRNA synthetase complex, it was recently discovered to dissociate from the complex and work as a potent tumor suppressor. Upon DNA damage, AIMP2 promotes apoptosis through the protective interaction with p53. However, it was not demonstrated whether AIMP2 was indeed pathologically linked to human cancer. In this work, we found that a splicing variant of AIMP2 lacking exon 2 (AIMP2-DX2) is highly expressed by alternative splicing in human lung cancer cells and patient's tissues. AIMP2-DX2 compromised pro-apoptotic activity of normal AIMP2 through the competitive binding to p53. The cells with higher level of AIMP2-DX2 showed higher propensity to form anchorage-independent colonies and increased resistance to cell death. Mice constitutively expressing this variant showed increased susceptibility to carcinogen-induced lung tumorigenesis. The expression ratio of AIMP2-DX2 to normal AIMP2 was increased according to lung cancer stage and showed a positive correlation with the survival of patients. Thus, this work identified an oncogenic splicing variant of a tumor suppressor, AIMP2/p38, and suggests its potential for anti-cancer target.

4-O-methylascochlorin-stimulated HIF-1α expression induces the epithelial mesenchymal transition and cell survival in breast cancer cells.

4-O-Methyl-ascochlorin (MAC), a derivative of the prenyl-phenol antibiotic ascochlorin, promotes accumulation of HIF-1α. In this study, we investigated the molecular mechanisms of the effect of MAC on cell migration and mesenchymal epithelial transition (EMT) processes in breast cancer cells. MAC upregulated cell motility and migration regardless of cell viability, and promoted EMT features by regulating EMT-related proteins and transcription. In addition, the MAC-induced increase in the EMT was closely related to activation of HIF-1α expression. However, the MAC-induced EMT was not associated with AMPK phosphorylation or intracellular ROS, which stimulate HIF-1α expression. Similarly, HIF-1α-mediated autophagy induced by MAC was not related to EMT-related proteins. Inhibition of HIF-1α activity inhibited MAC-stimulated cell migration and increased MAC-induced cell death, indicating that HIF-1α activation is important for MAC-mediated cell migration and survival in breast cancer cells. Together, these results suggest that MAC can be used to investigate the link between HIF-1α activation and other oncogenes or tumor suppressors in breast cancer cells.

Rg3-enriched red ginseng extract promotes lung cancer cell apoptosis and mitophagy by ROS production.

BACKGROUND: Red Ginseng has been used for many years to treat diseases. Ginsenoside Rg3 has documented therapeutic effects, including anticancer and anti-inflammatory activities. However, the anticancer effect of Rg3-enriched red ginseng extract (Rg3-RGE) and its underlying mechanisms have not been fully explored. We investigated whether Rg3-RGE plays an anti-tumor role in lung cancer cells. METHODS: To examine the effect of Rg3-RGE on lung cancer cells, we performed cell viability assays, flow cytometry, western blotting analysis, and immunofluorescence to monitor specific markers. RESULTS: Rg3-RGE significantly inhibited cell proliferation and induced mitochondria-dependent apoptosis. Furthermore, Rg3-RGE also increased expression of mitophagy-related proteins such as PINK1 and Parkin. In addition, treatment with Rg3-RGE and mitophagy inhibitors stimulated cell death by inducing mitochondria dysfunction. CONCLUSIONS: Rg3-RGE could be used as a therapeutic agent against lung cancer.

AIMP2/p38, the scaffold for the multi-tRNA synthetase complex, responds to genotoxic stresses via p53.

AIMP2/p38 is a scaffolding protein required for the assembly of the macromolecular tRNA synthetase complex. Here, we describe a previously unknown function for AIMP2 as a positive regulator of p53 in response to genotoxic stresses. Depletion of AIMP2 increased resistance to DNA damage-induced apoptosis, and introduction of AIMP2 into AIMP2-deficient cells restored the susceptibility to apoptosis. Upon DNA damage, AIMP2 was phosphorylated, dissociated from the multi-tRNA synthetase complex, and translocated into the nuclei of cells. AIMP2 directly interacts with p53, thereby preventing MDM2-mediated ubiquitination and degradation of p53. Mutations in AIMP2, affecting its interaction with p53, hampered its ability to activate p53. Nutlin-3 recovered the level of p53 and the susceptibility to UV-induced cell death in AIMP2-deficient cells. This work demonstrates that AIMP2, a component of the translational machinery, functions as proapoptotic factor via p53 in response to DNA damage.

Melittin-loaded Iron Oxide Nanoparticles Prevent Intracranial Arterial Dolichoectasia Development through Inhibition of Macrophage-mediated Inflammation.

Rationale: In intracranial arterial dolichoectasia (IADE) development, the feedback loop between inflammatory cytokines and macrophages involves TNF-α and NF-κB signaling pathways and leads to subsequent MMP-9 activation and extracellular matrix (ECM) degeneration. In this proof-of-concept study, melittin-loaded L-arginine-coated iron oxide nanoparticle (MeLioN) was proposed as the protective measure of IADE formation for this macrophage-mediated inflammation and ECM degeneration. Methods: IADE was created in 8-week-old C57BL/6J male mice by inducing hypertension and elastase injection into a basal cistern. Melittin was loaded on the surface of ION as a core-shell structure (hydrodynamic size, 202.4 nm; polydispersity index, 0.158). Treatment of MeLioN (2.5 mg/kg, five doses) started after the IADE induction, and the brain was harvested in the third week. In the healthy control, disease control, and MeLioN-treated group, the morphologic changes of the cerebral arterial wall were measured by diameter, thickness, and ECM composition. The expression level of MMP-9, CD68, MCP-1, TNF-α, and NF-κB was assessed from immunohistochemistry, polymerase chain reaction, and Western blot assay. Results: MeLioN prevented morphologic changes of cerebral arterial wall related to IADE formation by restoring ECM alterations and suppressing MMP-9 expression. MeLioN inhibited MCP-1 expression and reduced CD68-positive macrophage recruitments into cerebral arterial walls. MeLioN blocked TNF-α activation and NF-κB signaling pathway. In the Sylvian cistern, co-localization was found between the CD68-positive macrophage infiltrations and the MeLioN distributions detected on Prussian Blue and T2* gradient-echo MRI, suggesting the role of macrophage harboring MeLioN. Conclusions: The macrophage infiltration into the arterial wall plays a critical role in the MMP-9 secretion. MeLioN, designed for ION-mediated melittin delivery, effectively prevents IADE formation by suppressing macrophage-mediated inflammations and MMP activity. MeLioN can be a promising strategy preventing IADE development in high-risk populations.

Repeated aerosol delivery of carboxyl-terminal modulator protein suppresses tumor in the lungs of K-rasLA1 mice.

RATIONALE: Difficulties in achieving long-term survival of patients with lung cancer treated with conventional therapies suggest that novel approaches are required. 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 investigate the repeated effect of carboxyl-terminal modulator protein (CTMP) on multistage lung tumorigenesis. In this study, we addressed this question by studying the effects of lentivirus-based CTMP in the lungs of 9- and 13-week-old K-ras(LA1) mice, a model of lung cancer. METHODS: An aerosol of lentivirus-based CTMP was delivered into 9- and 13-week-old K-ras(LA1) mice, a model of lung cancer, through a nose-only inhalation system twice a week for 4 weeks. The effects of CTMP on lung cancer progression and Akt-related signals were evaluated. MEASUREMENTS AND MAIN RESULTS: Long-term repeated delivery of CTMP effectively reduced tumor progression in the lungs at different stages of development. Lentiviral-CTMP inhibited protein synthesis and cell cycle and altered Akt signaling pathway in the lungs of 9-week-old K-ras(LA1) mice, and increased apoptosis was observed in the lungs of 13-week-old K-ras(LA1) mice. CONCLUSIONS: Long-term repeated viral delivery of CTMP may provide a useful tool for designing lung tumor treatment.

PDCD4 inhibits lung tumorigenesis by the suppressing p62-Nrf2 signaling pathway and upregulating Keap1 expression.

Programmed cell death 4 (PDCD4) suppresses tumorigenesis, tumor progression, and invasion by inhibiting transcription and translation of oncogenes. However, the role of PDCD4 in lung tumorigenesis is unclear. Sequestosome1/p62 mediates cell proliferation, survival, and death through multiple signaling pathways, including autophagy and cell metabolism. p62/SQSTM1 is transcriptional target of Nrf2 and an important regulator of tumor growth. The aim of this study was to clarify whether and how PDCD4 regulates the p62-Nrf2 pathway, and how this regulation relates to tumorigenesis in human lung cancer cells. We established two stable human lung cancer cell lines, A549 and H460 that each overexpressed PDCD4. We found that PDCD4 overexpression decreased p62 expression levels and inhibited cell proliferation, and also increased the expression levels of cleaved PARP and cleaved caspase 3. Knockdown of p62 markedly increased the apoptotic rate of A549 and H460 cells overexpressing PDCD4. Furthermore levels of the epithelial-mesenchymal transition-related markers Slug, Snail, Twist1 and Vimentin were decreased and expression level of E-cadherin was increased in PDCD4-overexpressing cells. We also found that PDCD4 suppressed transcriptional activation of Nrf2 (an upstream regulator of p62) and increased endogenous levels of Keap1 (a negative regulator of Nrf2). Upregulation of Keap1 induced apoptosis and inhibited cell proliferation by suppressing activity of the p62-Nrf2 pathway in PDCD4-overexpressing cells. As anticipated, results from a mouse xenograft model showed that PDCD4 overexpression in xenografts inhibited cell proliferation and tumorigenesis. Taken together, our results demonstrate that PDCD4 overexpression, which increased Keap1 expression, reduces the levels and activity of the p62-Nrf2 pathway, thereby inhibiting tumorigenesis. Our findings suggest that PDCD4 may be a potential target for lung cancer therapies.

Ascofuranone suppresses invasion and F-actin cytoskeleton organization in cancer cells by inhibiting the mTOR complex 1 signaling pathway.

PURPOSE: Ascofuranone is an antiviral antibiotic that is known to exert multiple anti-tumor effects, including cell cycle arrest, inhibition of mitochondrial respiration, and inhibition of angiogenesis. In this study, we investigated the molecular mechanisms underlying the anti-metastatic effects of ascofuranone in insulin-like growth factor-I (IGF-1)-responsive cancer cells. METHODS: The inhibitory effect of ascofuranone on cancer cell migration and invasion was assessed using scratch wound healing and Matrigel invasion assays, respectively. F-actin cytoskeleton organization was assessed using FITC conjugated phalloidin staining. Target gene expression was evaluated using Western blotting and gene silencing was performed using siRNA transfections. Finally, the anti-metastatic effect of ascofuranone was investigated in vivo. RESULTS: We found that ascofuranone suppressed IGF-1-induced cell migration, invasion and motility in multiple cancer cell lines. The effects of ascofuranone on actin cytoskeleton organization were found to be mediated by suppression of the mTOR/p70S6K/4EBP1 pathway. Ascofuranone inhibited IGF-1-induced mTOR phosphorylation and actin cytoskeleton organization via upregulation of AMPK and downregulation of Akt phosphorylation. It also selectively suppressed the IGF-1-induced mTOR complex (mTORC)1 by phosphorylation of Raptor, but did not affect mTORC2. Furthermore, we found that focal adhesion kinase (FAK) activation decreased in response to ascofuranone, rapamycin, compound C and wortmannin treatment. Finally, we found that ascofuranone suppressed phosphorylation of FAK and mTOR and dephosphorylation of Raptor in cancerous metastatic lung tissues in vivo. CONCLUSIONS: Our data indicate that ascofuranone suppresses IGF-1-induced cancer cell migration and invasion by blocking actin cytoskeleton organization and FAK activation through inhibition of the mTORC1 pathway, and reveal a novel anti-metastatic function of this compound.

Ascofuranone inhibits epidermal growth factor-induced cell migration by blocking epithelial-mesenchymal transition in lung cancer cells.

Ascofuranone, an isoprenoid antibiotic initially purified from a culture broth of Ascochyta viciae, has multiple anticancer effects. However, the impacts of ascofuranone on the epithelial-mesenchymal transition (EMT) and epidermal growth factor (EGF)-induced effects on human lung cancer cell lines have not been previously reported. Here, we show that ascofuranone exerts its anticancer effects by inhibiting the EGF-induced EMT and cell migration in human lung cancer cell lines. Ascofuranone significantly inhibited EGF-induced migration and invasion by lung cancer cells, and suppressed EGF-induced morphologic changes by regulating the expression of EMT-associated proteins. In addition, ascofuranone upregulated E-cadherin, and downregulated fibronectin, vimentin, Slug, Snail, and Twist. Inhibition of ERK/AKT/mTOR promoted EGF-induced E-cadherin downregulation and inhibited EGF-induced vimentin upregulation in response to ascofuranone, implying that inhibition of the EGF-induced EMT by ascofuranone was mediated by the ERK and AKT/mTOR pathways. Inhibition of c-Myc suppressed EGF-induced vimentin upregulation, suggesting the involvement of c-Myc. Collectively, these findings suggest that ascofuranone inhibits tumor growth by blocking the EGF-induced EMT through a regulatory mechanism involving ERK, AKT/mTOR, and c-Myc in lung cancer cells.

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.

Biodegradable poly(ester amine) based on glycerol dimethacrylate and polyethylenimine as a gene carrier.

BACKGROUND: Polyethylenimine (PEI) vectors are widely used in gene delivery because of their high transfection efficiency owing to a unique proton sponge effect. An increase in molecular weight increases transfection efficiency, but simultaneously results in increased toxicity. Therefore, the design and synthesis of new degradable gene delivery carriers having high transfection efficiencies and reduced cytotoxicity are necessary. METHODS: In the present study degradable poly(ester amines) (PEAs) based on glycerol dimethacrylate (GDM) and low molecular weight branched polyethylenimine (LMW-PEI) were synthesized in anhydrous methanol at 60 degrees C following Michael addition reaction. The transfection efficiencies of the synthesized PEA/DNA complexes were evaluated using three different cell lines (HeLa, HepG2 and 293T cells) in vitro. RESULTS: PEAs with zeta potential in the range of 30-55 mV (at physiological pH) condensed plasmid DNA into nanosized particles (<150 nm) suitable for intracellular delivery. The PEAs degraded in a controlled fashion (t(1/2) of approximately 9-10 days). Compared with PEI 25K, the PEAs showed significantly lower cytotoxicity in three different cells. The PEAs demonstrated much higher transfection efficiency compared to conventional PEI 25K and Lipofectamine. The PEA synthesized using a 1 : 4 mole ratio of GDM to PEI [GDM/PEI-1.2 (1:4)] showed the highest transfection efficiency in HepG2 cells. Significantly higher pEGFP-N(2) reporter gene expression in 293T cells was achieved using these PEAs. The hyperosmotic effect of PEAs was demonstrated by the reduction in packed cell volume (PCV). The GDM/PEI-1.2 (1:4) showed comparable reduction in PCV with respect to glycerol in 293T cells. The effect of bafilomycin A(1) on transfection efficiency of PEAs on 293T cells indicated its endosomal buffering capacity. CONCLUSIONS: We hypothesized that the higher transfection efficiency of PEAs was the synergistic effect arising from hyperosmotic glycerol and endosomal buffering capacity of PEAs resulting from the presence of a glycerol backbone and PEI amine groups, respectively.

Low dietary inorganic phosphate affects the brain by controlling apoptosis, cell cycle and protein translation.

Inorganic phosphate (Pi) plays a key role in diverse physiologic functions. In a previous study, we showed that high dietary Pi perturbs brain growth through Akt/ERK signaling in developing mice. However, no study has investigated the response of the brain to low dietary Pi. In this study, we addressed this question by studying the effects of low dietary Pi on the cerebrum of developing mice. Two-week-old weaned mice were fed with a low phosphate diet for 4 weeks. At the end of the study, their cerebrum was dissected and signals important for protein translation, apoptosis and cell cycle were examined. The low phosphate diet did not cause physiologically significant changes; it increased the protein expression of phosphatase and tensin homolog deleted on chromosome 10 but decreased Akt activity. In addition, expression of eukaryotic translation initiation factor binding protein coupled with increased complex formation of eukaryotic translation initiation factor 4E/eukaryotic translation initiation factor binding protein 1 was induced in the cerebrum by low phosphate, leading to reduced cap-dependent protein translation. Finally, low phosphate facilitated apoptosis and suppressed signals important for the cell cycle in the cerebrum of dual-luciferase reporter mice. In summary, our results showed that a low phosphate diet affects the brain by controlling protein translation, apoptosis and cell cycle in developing mice. Our results support the hypothesis that Pi works as a stimulus capable of increasing or decreasing several pivotal genes for normal development and suggest that regulation of Pi consumption is important in maintaining a healthy life.

Serum immunoglobulin fused interferon-alpha inhibited tumor growth in athymic mice bearing colon 26 adenocarcinoma cells.

Interferon (IFN) has therapeutic potential for a wide range of infectious and proliferative disorders. However, the half-life of IFN is too short to have a stable therapeutic effect. To overcome this problem, serum immunoglobulin has been fused to IFN. In this study, the efficacy of serum immunoglobulin fused INFs (si-IFN1 and si-IFN2) was evaluated on athymic mice bearing colon 26 adenocarcinoma cells. Seven days after the implantation of tumor cells, each group of mice was injected once a week with si-IFN1 and si-IFN2 at two different concentrations (10 x : 30 microg/kg and 50 x : 150 microg/kg). A slight anti-tumoral effect was observed in all 10 x groups compared to the control. In the 50 x groups, however, si-IFN1 and si-IFN2 showed significant anti- tumoral effects compared to the control. To gain more information on the mechanisms associated with the decrease of tumor size, a Western blot assay of apoptosis-related molecules was performed. The protein expression of cytochrome c, caspase 9, 6, and 3 were increased by si-IFN1 and si-IFN2. These 2 IFNs also increased the expressions of p53, p21, Bax and Bad. Interestingly, si-IFN1 and si-IFN2 decreased the expression of VEGF-beta. Taken together, serum immunoglobulin fused IFNs increased therapeutic efficacy under current experimental condition.

Mitochondrial dysfunction induces the invasive phenotype, and cell migration and invasion, through the induction of AKT and AMPK pathways in lung cancer cells.

Mitochondria are well known for their important roles in oxidative phosphorylation, amino acid metabolism, fatty acid oxidation and ion homeostasis. Although the effects of mitochondrial dysfunction on tumorigenesis in various cancer cells have been reported, the correlation between mitochondrial dysfunction and epithelial­to­mesenchymal transition (EMT) in lung cancer development and metastasis has not been well elucidated. In the present study, the effects of mitochondrial dysfunction on EMT and migration in lung cancer cells were investigated using inhibitors of mitochondrial respiration, oligomycin A and antimycin A. Oligomycin A and antimycin A induced distinct mesenchymal­like morphological features in H23, H1793 and A549 lung cancer cells. In addition, they decreased the expression levels of the epithelial marker protein E­cadherin, but increased the expression levels of the mesenchymal marker proteins Vimentin, Snail and Slug. The results of immunofluorescence staining indicated that oligomycin A and antimycin A downregulated cortical E­cadherin expression and upregulated the expression of Vimentin. In addition, oligomycin A and antimycin A increased the migration and invasion of A549 lung cancer cells, and promoted the expression levels of phosphorylated (p)­protein kinase B (AKT) and p­AMP­activated protein kinase (AMPK). Notably, the production of reactive oxygen species by oligomycin A and antimycin A did not affect the expression of EMT protein markers. Conversely, treatment with the AKT inhibitor wortmannin and the AMPK inhibitor Compound C upregulated E­cadherin and downregulated Vimentin expression. These results suggested that oligomycin A and antimycin A may induce migration and invasion of lung cancer cells by inducing EMT via the upregulation of p­AKT and p­AMPK expression.

A biodegradable poly(ester amine) based on polycaprolactone and polyethylenimine as a gene carrier.

The aim of research was to develop and optimize delivery systems for plasmid DNA (pDNA) based on biodegradable polymers, in particular, poly(ester amine)s (PEAs), suitable for non-viral gene therapy. Poly(ester amine)s were successfully synthesized by Michael addition reaction between polycaprolactone (PCL) diacrylate and low molecular weight polyethylenimine (PEI). PEA/DNA complexes showed effective and stable DNA condensation with the particle sizes below 200nm, implicating its potential for intracellular delivery. PEAs showed controlled degradation and were essentially non-toxic in all three cells (293T: Human kidney carcinoma, HepG2: Human hepatoblastoma and HeLa: Human cervix epithelial carcinoma cell lines) at higher doses in contrast to PEI 25K. PEAs also revealed much higher transfection efficiencies in three cell lines as compared to PEI 25K. The highest reporter gene expression was observed for PCL/PEI-1.2 (MW 1200) complex having transfection efficiency 15-25 folds higher than PEI 25K in vitro. Also PEA/DNA complexes successfully transfected cells in vivo after aerosol administration than PEI 25K. These PEAs can be used as most efficient polymeric vectors which provide a versatile platform for further investigation of structure property relationship along with the controlled degradation, significant low cytotoxicity and high transfection efficiency.

Effects of 7-hydroxy-3-methoxycadalene on cell cycle, apoptosis and protein translation in A549 lung cancer cells.

Previously we reported that cadalene extracted from Zelkova serrata inhibited lung tumorigenesis in mice. However, the precise mechanism has not yet investigated. Here, we examined the effects of cadalene on signal pathways important for apoptosis, cell cycle, and protein translation in lung cancer cells. Our results showed that cadalene suppressed the expression of Akt and its phosphor-forms through controlling PI3K and PTEN. Cadalene also induced apoptosis through facilitating pro-apoptotic protein expression. In addition, cadalene caused cell cycle arrest and decreased mTOR-mediated protein translation. Taken together, cadalene may be developed as a lung cancer therapeutic agent in the future.

Aerosol delivery of urocanic acid-modified chitosan/programmed cell death 4 complex regulated apoptosis, cell cycle, and angiogenesis in lungs of K-ras null mice.

The low efficiency of conventional therapies in achieving long-term survival of patients with lung cancer calls for development of novel treatment options. Although several genes have been investigated for their antitumor activities through gene delivery, problems surrounding the methods used, such as efficiency, specificity, and toxicity, hinder application of such therapies in clinical settings. Aerosol gene delivery as nonviral and noninvasive method for gene therapy may provide an alternative for a safer and more effective treatment for lung cancer. In this study, imidazole ring-containing urocanic acid-modified chitosan (UAC) designed in previous study was used as a gene carrier. The efficiency of UAC carrier in lungs was confirmed, and the potential effects of the programmed cell death protein 4 (PDCD4) tumor suppressor gene on three major pathways (apoptosis, cell cycle, and angiogenesis) were evaluated. Aerosol containing UAC/PDCD4 complexes was delivered into K-ras null lung cancer model mice through the nose-only inhalation system developed by our group. Delivered UAC/PDCD4 complex facilitated apoptosis, inhibited pathways important for cell proliferation, and efficiently suppressed pathways important for tumor angiogenesis. In summary, results obtained by Western blot analysis, immunohistochemistry, and terminal deoxynucleotidyl transferase-mediated nick end labeling assay suggest that our aerosol gene delivery technique is compatible with in vivo gene delivery and can be applied as a noninvasive gene therapy.