BACKGROUND: The transcription factor POU2F1 regulates the expression levels of microRNAs in neoplasia. However, the miR-29b1/a cluster modulated by POU2F1 in gastric cancer (GC) remains unknown. METHODS: Gene expression in GC cells was evaluated using reverse-transcription polymerase chain reaction (PCR), western blotting, immunohistochemistry, and RNA in situ hybridization. Co-immunoprecipitation was performed to evaluate protein interactions. Transwell migration and invasion assays were performed to investigate the biological behavior of GC cells. MiR-29b1/a cluster promoter analysis and luciferase activity assay for the 3'-UTR study were performed in GC cells. In vivo tumor metastasis was evaluated in nude mice. RESULTS: POU2F1 is overexpressed in GC cell lines and binds to the miR-29b1/a cluster promoter. POU2F1 is upregulated, whereas mature miR-29b-3p and miR-29a-3p are downregulated in GC tissues. POU2F1 promotes GC metastasis by inhibiting miR-29b-3p or miR-29a-3p expression in vitro and in vivo . Furthermore, PIK3R1 and/or PIK3R3 are direct targets of miR-29b-3p and/or miR-29a-3p , and the ectopic expression of PIK3R1 or PIK3R3 reverses the suppressive effect of mature miR-29b-3p and/or miR-29a-3p on GC cell metastasis and invasion. Additionally, the interaction of PIK3R1 with PIK3R3 promotes migration and invasion, and miR-29b-3p , miR-29a-3p , PIK3R1 , and PIK3R3 regulate migration and invasion via the phosphatidylinositol 3-kinase/protein kinase B/mammalian target of rapamycin (PI3K/Akt/mTOR) pathway in GC cells. In addition, POU2F1 , PIK3R1 , and PIK3R3 expression levels negatively correlated with miR-29b-3p and miR-29a-3p expression levels in GC tissue samples. CONCLUSIONS The POU2F1 - miR-29b-3p / miR-29a-3p-PIK3R1 / PIK3R1 signaling axis regulates tumor progression and may be a promising therapeutic target for GC.
MicroRNAs/metabolism* ; Humans ; Stomach Neoplasms/pathology* ; Cell Line, Tumor ; Cell Movement/physiology* ; Phosphatidylinositol 3-Kinases/metabolism* ; Animals ; Mice ; Octamer Transcription Factor-1/metabolism* ; Mice, Nude ; Class Ia Phosphatidylinositol 3-Kinase/metabolism* ; Neoplasm Invasiveness ; Gene Expression Regulation, Neoplastic/genetics* ; Male ; Immunohistochemistry ; Female

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 (AngII) is a crucial hormone that affects vasoconstriction and exerts hypertrophic effects on vascular smooth muscle cells. Here, we showed that phosphatidylinositol 3-kinase-dependent calcium mobilization plays pivotal roles in AngII-induced vascular constriction. Stimulation of rat aortic vascular smooth muscle cell (RASMC)-embedded collagen gel with AngII rapidly induced contraction. AngII-induced collagen gel contraction was blocked by pretreatment with a phosphatidylinositol 3-kinase (PI3K) inhibitor (LY294002) whereas ERK inhibitor (PD98059) was not effective. AngII-induced collagen gel contraction was significantly blocked by extracellular calcium depletion by EGTA or by nifedipine which is an L-type calcium channel blocker. In addition, AngII-induced calcium mobilization was also blocked by nifedipine and EGTA, whereas intracellular calcium store-depletion by thapsigargin was not effective. Finally, pretreatment of rat aortic ring with LY294002 and nifedipine significantly reduced AngII-induced constriction. Given these results, we suggest that PI3K-dependent activation of L-type calcium channels might be involved in AngII-induced vascular constriction.
1-Phosphatidylinositol 3-Kinase/*metabolism/pharmacology ; Angiotensin II/metabolism/*pharmacology ; Animals ; Aorta, Thoracic/*drug effects/physiology ; Calcium Channels, L-Type/drug effects/*metabolism ; Muscle Contraction/drug effects ; Muscle, Smooth, Vascular/drug effects/enzymology ; Rats ; Rats, Sprague-Dawley ; Signal Transduction/*drug effects ; Specific Pathogen-Free Organisms ; Vasoconstriction/*drug effects

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

BACKGROUNDAlthough the insulinotropic role of glucagon-like peptide-1 (GLP-1) in type 2 diabetes mellitus has been substantiated, its role in cardioprotection remains largely unknown. This study aimed to determine the effects of GLP-1 on injury of rats cardiac myocytes induced by hypoxia-reoxygenation (H/R) and the possible mechanisms.

METHODSThe cultured neonatal rats cardiac myocytes were randomly divided into seven groups: the normal control group, the H/R group, the GLP-1 + H/R group, the GLP-1 + H/R + UO126 (the p42/44 mitogen-activated protein kinase (MAPK) inhibitor) group, the GLP-1 + H/R + LY294002 (phosphatidylinositol 3-kinase (PI3K) inhibitor) group, the H/R + UO126 group, and the H/R + LY294002 group. The lactate dehydrogenase (LDH) activity, apoptosis rate of cardiac myocytes, and caspase-3 activity were detected after the injury of H/R.

RESULTSCompared with the normal control group, the activity of LDH, cardiac myocyte apoptosis rate, and caspase-3 activity all increased significantly in the H/R group (P < 0.01). Compared with the H/R group, these three indices all decreased in the H/R + GLP-1 group (P < 0.01). However, the changes of LDH activity, apoptosis rate, and caspase-3 activity were inhibited by LY294002 and UO126 respectively.

CONCLUSIONSGLP-1 can directly act on cardiac myocytes and protect them from H/R injury mainly by inhibiting their apoptosis. Its mechanism may be through the PI3K-Akt pathway and the MAPK signaling pathway.

Actins ; analysis ; Animals ; Butadienes ; pharmacology ; Cell Hypoxia ; Cells, Cultured ; Chromones ; pharmacology ; Extracellular Signal-Regulated MAP Kinases ; physiology ; Glucagon-Like Peptide 1 ; pharmacology ; MAP Kinase Signaling System ; Morpholines ; pharmacology ; Myocytes, Cardiac ; drug effects ; Nitriles ; pharmacology ; Phosphatidylinositol 3-Kinases ; physiology ; Rats ; Rats, Wistar

Akt plays pivotal roles in many physiological responses including growth, proliferation, survival, metabolism, and migration. In the current studies, we have evaluated the isoform-specific role of akt in lysophosphatidic acid (LPA)-induced cell migration. Ascites from ovarian cancer patients (AOCP) induced mouse embryo fibroblast (MEF) cell migration in a dose-dependent manner. On the other hand, ascites from liver cirrhosis patients (ALCP) did not induce MEF cell migration. AOCP-induced MEF cell migration was completely blocked by pre-treatment of cells with LPA receptor antagonist, Ki16425. Both LPA- and AOCP-induced MEF cell migration was completely attenuated by PI3K inhibitor, LY294002. Furthermore, cells lacking Akt1 displayed defect in LPA-induced cell migration. Re-expression of Akt1 in DKO (Akt1(-/-)Akt2(-/-)) cells restored LPA-induced cell migration, whereas re-expression of Akt2 in DKO cells could not restore the LPA-induced cell migration. Finally, Akt1 was selectively phosphorylated by LPA and AOCP stimulation. These results suggest that LPA is a major factor responsible for AOCP-induced cell migration and signaling specificity of Akt1 may dictate LPA-induced cell migration.
1-Phosphatidylinositol 3-Kinase/physiology ; Adult ; Aged ; Animals ; Ascites/pathology ; Cell Movement/*drug effects ; Cells, Cultured ; Embryo, Mammalian ; Enzyme Activation/drug effects ; Female ; Humans ; Liver Cirrhosis/pathology ; Lysophospholipids/isolation & purification/*pharmacology ; Mice ; Middle Aged ; Ovarian Neoplasms/pathology ; Pregnancy ; Proto-Oncogene Proteins c-akt/*agonists/*metabolism ; Substrate Specificity

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

Endothelin can affect the contractile properties of cardiacmyocyte, stimulate myocyte growth and myofibrillogenesis, and increase resistance to apoptosis by intracellular signaling pathways. This article briefly reviews the regulative effects of these signaling pathways including protein kinase C, mitogen activated protein kinase, and phosphoinositide 3'-OH kinase/protein kinase B.
Animals ; Endothelin-1 ; physiology ; Endothelins ; physiology ; Humans ; Mitogen-Activated Protein Kinases ; metabolism ; Myocardial Contraction ; drug effects ; Myocytes, Cardiac ; metabolism ; Phosphatidylinositol 3-Kinases ; metabolism ; Protein Kinase C ; metabolism ; Signal Transduction

Cyclooxygenase-2 (COX-2) has been reported to be associated with tumor development and progression as well as to protect cells from apoptosis induced by various cellular stresses. Through a tetracycline-regulated COX-2 overexpression system, we found that COX-2 inhibits detachment-induced apoptosis (anoikis) in a human bladder cancer cell line, EJ. We also found that the inhibition of anoikis by COX-2 results from activation of the PI-3K/Akt pathway as evidenced by suppression of the COX-2 effect on anoikis by a PI-3K inhibitor, LY294002. Furthermore, COX-2 enhanced Mcl-1 expression in the anoikis process, implying that Mcl-1 also may be involved in mediating the survival function of COX-2. Together, these results suggest that COX-2 inhibits anoikis by activation of the PI-3K/Akt pathway and probably by enhancement of Mcl-1 expression in human bladder cancer cells. This anti- anoikis effect of COX-2 may be a part of mechanisms to promote tumor development and progression.
1-Phosphatidylinositol 3-Kinase/*metabolism ; Anoikis/*physiology ; Bladder Neoplasms/*metabolism/pathology ; Enzyme Activation ; Humans ; Neoplasm Proteins/*metabolism ; Prostaglandin-Endoperoxide Synthase/*metabolism ; Protein-Serine-Threonine Kinases/*metabolism ; Proto-Oncogene Proteins/*metabolism ; Proto-Oncogene Proteins c-bcl-2/*metabolism ; Research Support, Non-U.S. Gov't ; Signal Transduction ; Transfection ; Tumor Cells, Cultured

Hepatitis B virus x gene product (HBx) is known to be a transactivator of transcriptional elements that regulate the expression of a variety of genes associated with the growth, differentiation, survival and the apoptosis of cells. However, the exact mechanism of the activation and inhibition of cellular events by HBx remains uncertain. The present study was designed to measure the effect of HBx, on the signal transduction pathways associated with intracellular Ca(2+)mobilization following HBx transfection in the stable Chang liver cells (CHL-X). Enhanced cell proliferation by HBx in CHL-X was confirmed by MTT assay and by the immunodetection of PCNA. The transactivation of AP-1 by HBx induced in CHL-X was inhibited by cyclosporin A (CsA), a mitochondrial Ca(2+)channel blocker and by BAPTA-AM, a cytosolic Ca(2+)blocker. Activation of the SAPK/JNK signaling pathway by HBx was evidenced by the increased phosphorylations of c-Jun (Ser63) and of JNK (Thr183/Tyr185). Increased phospho-Erk/Erk and phospho-Raf1/Raf in HBx-induced CHL-X indicated that HBx might stimulate the MAPK pathway. PI3K activity and cytosolic free Ca(2+)levels were elevated in HBx-induced CHL-X. These results imply that HBx transactivates both JNK and MAPK signal transduction pathways in association with the mobilization of cytosolic Ca(2+).
1-Phosphatidylinositol 3-Kinase/metabolism ; Calcium/*metabolism ; Calcium Signaling/*physiology ; Cell Division ; Hepatitis B Virus/*metabolism ; Human ; Liver/*metabolism ; Mitogen-Activated Protein Kinases/metabolism ; Trans-Activators/*metabolism ; Transcription Factor AP-1/metabolism