At this time, brain tumor stem cells remain a controversial hypothesis while malignant brain tumors continue to present a dire prognosis of severe morbidity and mortality. Yet, brain tumor stem cells may represent an essential cellular target for glioma therapy as they are postulated to be the tumorigenic cells responsible for recurrence. Targeting oncogenic pathways that are essential to the survival and growth of brain tumor stem cells represents a promising area for developing therapeutics. However, due to the multiple oncogenic pathways involved in glioma, it is necessary to determine which pathways are the essential targets for therapy. Furthermore, research still needs to comprehend the morphogenic processes of cell populations involved in tumor formation. Here, we review research and discuss perspectives on models of glioma in order to delineate the current issues in defining brain tumor stem cells as therapeutic targets in models of glioma.
1-Phosphatidylinositol 3-Kinase/genetics/metabolism ; Animals ; Brain Neoplasms/genetics/*metabolism/*pathology/therapy ; Glioma/genetics/*metabolism/*pathology/therapy ; Humans ; Neoplastic Stem Cells/*metabolism/*pathology ; Receptors, Notch/genetics/metabolism ; Signal Transduction/genetics/physiology

Angiotensin II (Ang II) stimulates migration of vascular smooth muscle cell (VSMC) in addition to its contribution to contraction and hypertrophy. It is well established that Rho GTPases regulate cellular contractility and migration by reorganizing the actin cytoskeleton. Ang II activates Rac1 GTPase, but its upstream guanine nucleotide exchange factor (GEF) remains elusive. Here, we show that Ang II-induced VSMC migration occurs in a betaPIX GEF-dependent manner. betaPIX-specific siRNA treatment significantly inhibited Ang II-induced VSMC migration. Ang II activated the catalytic activity of betaPIX towards Rac1 in dose- and time-dependent manners. Activity reached a peak at 10 min and declined close to a basal level by 30 min following stimulation. Pharmacological inhibition with specific kinase inhibitors revealed the participation of protein kinase C, Src family kinase, and phosphatidylinositol 3-kinase (PI3-K) upstream of betaPIX. Both p21-activated kinase and reactive oxygen species played key roles in cytoskeletal reorganization downstream of betaPIX-Rac1. Taken together, our results suggest that betaPIX is involved in Ang II-induced VSMC migration.
1-Phosphatidylinositol 3-Kinase/metabolism ; Angiotensin II/*metabolism ; Animals ; *Cell Movement ; Cells, Cultured ; Guanine Nucleotide Exchange Factors/genetics/*metabolism ; Muscle, Smooth, Vascular/cytology ; Myocytes, Smooth Muscle/*cytology ; NADPH Oxidase/metabolism ; Protein Kinase C/metabolism ; RNA, Small Interfering/genetics ; Rats ; Rats, Sprague-Dawley ; p21-Activated Kinases/metabolism ; rac1 GTP-Binding Protein/metabolism ; src-Family Kinases/metabolism

Overexpression of HER2 correlates with more aggressive tumors and increased resistance to cancer chemotherapy. However, a functional comparison between the HER2high/HER3 and the HER2low/HER3 dimers on tumor metastasis has not been conducted. Herein we examined the regulation mechanism of heregulin-beta1 (HRG)-induced MMP-1 and -9 expression in breast cancer cell lines. Our results showed that the basal levels of MMP-1 and -9 mRNA and protein expression were increased by HRG treatment. In addition, HRG-induced MMP-1 and -9 expression was significantly decreased by MEK1/2 inhibitor, U0126 but not by phosphatidylinositol 3-kinase (PI-3K) inhibitor, LY294002. To confirm the role of MEK/ERK pathway on HRG-induced MMP-1 and -9 expression, MCF7 cells were transfected with constitutively active adenoviral-MEK (CA-MEK). The level of MMP-1 and -9 expressions was increased by CA-MEK. MMP-1 and -9 mRNA and protein expressions in response to HRG were higher in HER2 overexpressed cells than in vector alone. The phosphorylation of HER2, HER3, ERK, Akt, and JNK were also significantly increased in HER2 overexpressed MCF7 cells compared with vector alone. HRG-induced MMP-1 and -9 expressions were significantly decreased by lapatinib, which inhibits HER1 and HER2 activity, in both vector alone and HER2 overexpressed MCF7 cells. Finally, HRG-induced MMP-1 and MMP-9 expression was decreased by HER3 siRNA overexpression. Taken together, we suggested that HRG-induced MMP-1 and MMP-9 expression is mediated through HER3 dependent pathway and highly expressed HER2 may be associated with more aggressive metastasis than the low expressed HER2 in breast cancer cells.
Breast Neoplasms/enzymology/*genetics/*metabolism ; Butadienes/pharmacology ; Cell Line, Tumor ; Dose-Response Relationship, Drug ; Enzyme Inhibitors/pharmacology ; Female ; Gene Expression ; Gene Expression Regulation, Neoplastic/drug effects ; Humans ; MAP Kinase Signaling System ; MCF-7 Cells ; Matrix Metalloproteinase 1/*genetics/metabolism ; Matrix Metalloproteinase 9/*genetics/metabolism ; Neuregulin-1/*pharmacology ; Nitriles/pharmacology ; Phosphatidylinositol 3-Kinases/metabolism ; Protein Kinase Inhibitors/pharmacology ; Protein Multimerization ; Proto-Oncogene Proteins c-akt/metabolism ; Quinazolines/pharmacology ; Receptor, erbB-2/genetics/*metabolism ; Receptor, erbB-3/*metabolism

The expression of hypoxia-inducible factor (HIF) is influenced by reactive oxygen species (ROS). Effect of bilirubin on HIF-1 expression in proximal tubular cells was investigated under physiological oxygen concentration, which is relative hypoxic condition mimicking oxygen content in the medulla of renal tissue. The human kidney (HK2) cells were cultured in 5% oxygen with or without bilirubin. HIF-1alpha protein expression was increased by bilirubin treatment at 0.01-0.2 mg/dL concentration. The messenger RNA expression of HIF-1alpha was increased by 1.69+/-0.05 folds in the cells cultured with 0.1 mg/dL bilirubin, compared to the control cells. The inhibitors of PI3K/mTOR, PI3K/AKT, and ERK 1/2 pathways did not attenuate increased HIF-1alpha expression by bilirubin. HIF-1alpha expression decreased by 10 microM exogenous hydrogen peroxide (H2O2); scavenger of ROS with or without bilirubin in the HK2 cells increased HIF-1alpha concentration more than that in the cells without bilirubin. Exogenous H2O2 decreased the phosphorylation of P70S6 kinase, which was completely reversed by bilirubin treatment. Knockdown of NOX4 gene by small interfering RNA (siRNA) increased HIF-1alpha mRNA expression. In coonclusion, bilirubin enhances HIF-1alpha transcription as well as the up-regulation of HIF-1alpha protein translation through the attenuation of ROS and subunits of NADPH oxidase.
Bilirubin/*pharmacology ; Cell Line ; Epithelial Cells/cytology/metabolism ; Humans ; Hydrogen Peroxide/toxicity ; Hypoxia-Inducible Factor 1, alpha Subunit/genetics/*metabolism ; Kidney Tubules, Proximal/cytology ; Mitogen-Activated Protein Kinase 1/metabolism ; Mitogen-Activated Protein Kinase 3/metabolism ; NADPH Oxidase/antagonists & inhibitors/genetics/metabolism ; Oxygen/*pharmacology ; Phosphatidylinositol 3-Kinases/metabolism ; Phosphorylation/drug effects ; Proto-Oncogene Proteins c-akt/metabolism ; RNA Interference ; Ribosomal Protein S6 Kinases, 70-kDa/metabolism ; Signal Transduction/drug effects ; TOR Serine-Threonine Kinases/metabolism ; Transcriptional Activation/*drug effects ; Up-Regulation/drug effects

Nitric oxide (NO) seems to play a pivotal role in the vascular endothelial growth factor (VEGF)-induced endothelial cell proliferation. This study was designed to investigate the role and intracellular signal pathway of endothelial nitric oxide synthase (eNOS) activation induced by VEGF. ECV 304 cells were treated with betaVEGF(165) and then cell proliferation, eNOS protein and mRNA expression levels were analyzed to elucidate the functional role of eNOS in cell proliferation induced by VEGF. After exposure of cells to betaVEGF(165) , eNOS activity and cell growth were increased by approximately two-fold in the betaVEGF(165) -treated cells compared to the untreated cells. In addition, VEGF stimulated eNOS expression at both the mRNA and protein levels in a dose-dependent manner. Phosphatidylinositol-3 kinase (PI-3K) inhibitors were used to assess PI-3K involvement in eNOS regulation. LY294002 was found to attenuate VEGF-stimulated eNOS expression. Wortmannin was not as effective as LY294002, but the reduction effect was detectable. Cells activated by VEGF showed increased ERK1/2 levels. Moreover, the VEGF-induced eNOS expression was reduced by the PD98059, MAPK pathway inhibitor. This suggests that eNOS expression might be regulated by PI-3K and the ERK1/2 signaling pathway. In conclusion, betaVEGF(165) induces ECV 304 cell proliferation via the NO produced by eNOS. In addition, eNOS may be regulated by the PI-3K or mitogen-activated protein kinase pathway.
1-Phosphatidylinositol 3-Kinase/*antagonists & inhibitors ; Cell Division/drug effects ; Cell Line ; Endothelial Growth Factors/*metabolism/pharmacology ; Endothelium, Vascular/cytology ; *Gene Expression Regulation, Enzymologic ; Lymphokines/*metabolism/pharmacology ; MAP Kinase Signaling System ; Mitogen-Activated Protein Kinase 1/*antagonists & inhibitors ; Mitogen-Activated Protein Kinase 3 ; Mitogen-Activated Protein Kinases/*antagonists & inhibitors ; Nitric Oxide Synthase/*genetics/metabolism ; Nitric Oxide Synthase Type III ; Signal Transduction ; Vascular Endothelial Growth Factor A ; Vascular Endothelial Growth Factors

To investigate the role of the extracellular signal-regulated kinase (ERK1/2) and PI3K/AKT/ mTOR signal pathway inducing bone marrow mesenchymal stem cells (BMSCs) differentiation into neural cells, mouse bone marrow-derived mesenchymal stem cell lines D1 cells were used as research object. And they were divided into control groups and salidroside (SD) groups. Different concentrations (5, 25, 50, 100 and 200 microg x mL(-1) of SD were used and SD (100 microg x mL(-1)) was used to induce at different time (0.5, 1, 3, 6, 9, 12, 24, 48 and 72 h). The immunofluorescence staining chemical technology, real-time PCR and Western blotting were used to detect the positive rates of NSE, MAP2, beta-Tubulin III, NES, GFAP and the expression levels of beta-Tubulin III, NSE, ERK1/2, AKT. The expression of ERK1/2 and NSE was detected when the ERK1/2 and PI3K/AKT/ mTOR signal pathway was blocked by PD98059 and LY294002. It indicated that the positive rates of NSE, MAP2, beta-Tubulin III, NES and GFAP were gradually enhanced with time increased. The expression level of NSE and beta-Tubulin III protein were significantly higher than those in control groups (P < 0.01). The expression of ERK1/2, AKT mRNA and protein were higher with concentration and time increased. When the ERK1/2 and PI3K/AKT/mTOR signal pathway were blocked, the expression levels of NSE, NES and beta-Tubulin III mRNA and NSE protein were inhibited significantly. It points out that SD can stimulate the ERK1/2 and PI3K/AKT/mTOR signal pathway to promote BMSCs differentiation into neural cells.
Animals ; Bone Marrow Cells ; cytology ; Cell Differentiation ; drug effects ; Cells, Cultured ; Chromones ; pharmacology ; Enzyme Inhibitors ; pharmacology ; Flavonoids ; pharmacology ; Glial Fibrillary Acidic Protein ; metabolism ; Glucosides ; antagonists & inhibitors ; isolation & purification ; pharmacology ; MAP Kinase Signaling System ; drug effects ; Mesenchymal Stromal Cells ; cytology ; Mice ; Microtubule-Associated Proteins ; metabolism ; Mitogen-Activated Protein Kinase 1 ; genetics ; metabolism ; Mitogen-Activated Protein Kinase 3 ; genetics ; metabolism ; Morpholines ; pharmacology ; Nestin ; metabolism ; Neurons ; cytology ; metabolism ; Phenols ; antagonists & inhibitors ; isolation & purification ; pharmacology ; Phosphatidylinositol 3-Kinases ; metabolism ; Phosphopyruvate Hydratase ; genetics ; metabolism ; Plants, Medicinal ; chemistry ; Protein Kinase Inhibitors ; pharmacology ; Proto-Oncogene Proteins c-akt ; genetics ; metabolism ; RNA, Messenger ; metabolism ; Rhodiola ; chemistry ; Signal Transduction ; drug effects ; TOR Serine-Threonine Kinases ; metabolism ; Tubulin ; metabolism

Phytosphingosine-1-phosphate (PhS1P) was found to stimulate an intracellular calcium increase via phospholipase C but not pertussis toxin (PTX)- sensitive G-proteins in L2071 mouse fibroblasts. PhS1P also activated ERK and p38 kinase, and these activations by PhS1P were inhibited by PTX. Moreover, PhS1P stimulated the chemotactic migration of L2071 cells via PTX-sensitive Gi protein(s). In addition, the PhS1P-induced chemotactic migration of L2071 cells was also dramatically inhibited by LY294002 and SB203580 (inhibitors of phosphoinositide 3-kinase and p38 kinase, respectively). L2071 cells are known to express four S1P receptors, i.e., S1P1, S1P2, S1P3, and S1P4, and pretreatment with an S1P1 and S1P3 antagonist (VPC 23019) did not affect on PhS1P-induced chemotaxis. This study demonstrates that PhS1P stimulates at least two different signaling cascades, one is a PTX-insensitive but phospholipase C dependent intracellular calcium increase, and the other is a PTX-sensitive chemotactic migration mediated by phosphoinositide 3-kinase and p38 kinase.
1-Phosphatidylinositol 3-Kinase/metabolism ; Animals ; Calcium Signaling/drug effects ; Chemotaxis/*drug effects ; Estrenes/pharmacology ; Extracellular Signal-Regulated MAP Kinases/metabolism ; Fibroblasts/*cytology/*drug effects ; GTP-Binding Proteins/*metabolism ; Gene Expression Regulation/drug effects ; Humans ; Mice ; Pertussis Toxin/*pharmacology ; Phosphorylation/drug effects ; Pyrrolidinones/pharmacology ; RNA, Messenger/genetics/metabolism ; Receptors, Lysosphingolipid/genetics/metabolism ; Sphingosine/*analogs & derivatives/pharmacology ; p38 Mitogen-Activated Protein Kinases/metabolism

Matrix metalloproteinase-9 (MMP-9) may play an important role in emphysematous change in chronic obstructive pulmonary disease (COPD), one of the leading causes of mortality and morbidity worldwide. We previously reported that simvastatin, an inhibitor of HMG-CoA reductase, attenuates emphysematous change and MMP-9 induction in the lungs of rats exposed to cigarette smoke. However, it remained uncertain how cigarette smoke induced MMP-9 and how simvastatin inhibited cigarette smoke-induced MMP-9 expression in alveolar macrophages (AMs), a major source of MMP-9 in the lungs of COPD patients. Presently, we examined the related signaling for MMP-9 induction and the inhibitory mechanism of simvastatin on MMP-9 induction in AMs exposed to cigarette smoke extract (CSE). In isolated rat AMs, CSE induced MMP-9 expression and phosphorylation of ERK and Akt. A chemical inhibitor of MEK1/2 or PI3K reduced phosphorylation of ERK or Akt, respectively, and also inhibited CSE-mediated MMP-9 induction. Simvastatin reduced CSE-mediated MMP-9 induction, and simvastatin-mediated inhibition was reversed by farnesyl pyrophosphate (FPP) or geranylgeranyl pyrophosphate (GGPP). Similar to simvastatin, inhibition of FPP transferase or GGPP transferase suppressed CSE-mediated MMP-9 induction. Simvastatin attenuated CSE-mediated activation of RAS and phosphorylation of ERK, Akt, p65, IkappaB, and nuclear AP-1 or NF-kappaB activity. Taken together, these results suggest that simvastatin may inhibit CSE-mediated MMP-9 induction, primarily by blocking prenylation of RAS in the signaling pathways, in which Raf-MEK-ERK, PI3K/Akt, AP-1, and IkappaB-NF-kappaB are involved.
1-Phosphatidylinositol 3-Kinase/metabolism ; Alkyl and Aryl Transferases/metabolism ; Animals ; Anticholesteremic Agents/pharmacology ; Cells, Cultured ; Enzyme Inhibitors/metabolism/pharmacology ; Extracellular Signal-Regulated MAP Kinases/metabolism ; Gene Expression Regulation, Enzymologic/*drug effects ; I-kappa B Kinase/antagonists & inhibitors/metabolism ; Macrophages, Alveolar/cytology/*drug effects/*enzymology ; Matrix Metalloproteinase 9/genetics/*metabolism ; Mitogen-Activated Protein Kinase Kinases/metabolism ; Polyisoprenyl Phosphates/metabolism ; Proto-Oncogene Proteins c-akt/metabolism ; Rats ; Sesquiterpenes/metabolism ; Signal Transduction/physiology ; Simvastatin/*pharmacology ; Smoke/*adverse effects ; *Tobacco/adverse effects/chemistry

Adhesion and migration of vascular smooth muscle cells (VSMCs) play an important role in the pathogenesis of atherosclerosis. These processes involve the interaction of VSMCs with extracellular matrix proteins. Here, we investigated integrin isoforms and signaling pathways mediating the adhesion and migration of VSMCs on betaig-h3, a transforming growth factor (TGF)-beta-inducible extracellular matrix protein that is elevated in atherosclerotic plaques. Adhesion assays showed that the alphavbeta5 integrin is a functional receptor for the adhesion of aortic VSMCs to betaig-h3. An YH18 motif containing amino acids between 563 and 580 of betaig-h3 was an essential motif for the adhesion and growth of VSMCs. Interaction between the YH18 motif and the alphavbeta5 integrin was responsible for the migration of VSMCs on betaig-h3. Inhibitors of phosphatidylinositide 3-kinase, extracellular signal-regulated kinase (ERK), and Src kinase reduced the adhesion and migration of VSMCs on betaig-h3. betaig-h3 triggered phosphorylation and activation of AKT, ERK, focal adhesion kinase, and paxillin mediating the adhesion and migration of VSMCs. Taken together, these results suggest that betaig-h3 and alphavbeta5 integrin play a role in the adhesion and migration of VSMCs during the pathogenesis of atherosclerosis.
src-Family Kinases/antagonists & inhibitors ; Transforming Growth Factor beta/genetics/*physiology ; Signal Transduction/*physiology ; Receptors, Vitronectin/genetics/*physiology ; Protein-Tyrosine Kinases/antagonists & inhibitors ; Paxillin/metabolism ; Myocytes, Smooth Muscle/drug effects/metabolism ; Muscle, Smooth, Vascular/cytology/drug effects/*metabolism ; Morpholines/pharmacology ; Molecular Sequence Data ; Integrins/genetics/*physiology ; Humans ; Flavonoids/pharmacology ; Extracellular Signal-Regulated MAP Kinases/antagonists & inhibitors ; Extracellular Matrix Proteins/genetics/*physiology ; Enzyme Inhibitors/pharmacology ; Chromones/pharmacology ; Cells, Cultured ; Cell Movement/*physiology ; Cell Adhesion/physiology ; Animals ; Amino Acid Sequence ; Amino Acid Motifs/genetics ; 1-Phosphatidylinositol 3-Kinase/antagonists & inhibitors