epidermal-growth-factor and Hypoxia

The carotid body may undergo plasticity changes during development/ageing and in response to environmental (hypoxia and hyperoxia), metabolic, and inflammatory stimuli. The different cell types of the carotid body express a wide series of growth factors and corresponding receptors, which play a role in the modulation of carotid body function and plasticity. In particular, type I cells express nerve growth factor, brain-derived neurotrophic factor, neurotrophin 3, glial cell line-derived neurotrophic factor, ciliary neurotrophic factor, insulin-like-growth factor-I and -II, basic fibroblast growth factor, epidermal growth factor, transforming growth factor-α and -β, interleukin-1β and -6, tumor necrosis factor-α, vascular endothelial growth factor, and endothelin-1. Many specific growth factor receptors have been identified in type I cells, indicating autocrine/paracrine effects. Type II cells may also produce growth factors and express corresponding receptors. Future research will have to consider growth factors in further experimental models of cardiovascular, metabolic, and inflammatory diseases and in human (normal and pathologic) samples. From a methodological point of view, microarray and/or proteomic approaches would permit contemporary analyses of large groups of growth factors. The eventual identification of physical interactions between receptors of different growth factors and/or neuromodulators could also add insights regarding functional interactions between different trophic mechanisms.

Topics: Animals; Brain-Derived Neurotrophic Factor; Carotid Body; Ciliary Neurotrophic Factor; Epidermal Growth Factor; Fibroblast Growth Factor 2; Gene Expression Regulation; Glial Cell Line-Derived Neurotrophic Factor; Humans; Hyperoxia; Hypoxia; Insulin-Like Growth Factor I; Nerve Growth Factor; Neurotrophin 3; Receptors, Growth Factor; Transforming Growth Factor alpha; Transforming Growth Factor beta; Vascular Endothelial Growth Factor A

Among proposed mechanisms to explain digital clubbing, the release of cytokines, specifically vascular endothelial growth factor and platelet-derived growth factor, from aggregated platelets and megakaryocytes has emerged as the most likely explanation. This review describes these and other contributory processes.

Topics: Bradykinin; Cytokines; Epidermal Growth Factor; Ferritins; Hemiplegia; Hepatocyte Growth Factor; Human Growth Hormone; Humans; Hypoxia; Intercellular Signaling Peptides and Proteins; Interleukin-6; Osteoarthropathy, Primary Hypertrophic; Osteoarthropathy, Secondary Hypertrophic; Platelet-Derived Growth Factor; Prostaglandins; Serotonin; Transforming Growth Factor beta1; Tumor Necrosis Factor-alpha; Vascular Endothelial Growth Factor A; von Willebrand Factor

Cripto-1 is critical for early embryonic development and, together with its ligand Nodal, has been found to be associated with the undifferentiated status of mouse and human embryonic stem cells. Like other embryonic genes, Cripto-1 performs important roles in the formation and progression of several types of human tumors, stimulating cell proliferation, migration, epithelial to mesenchymal transition, and tumor angiogenesis. Several studies have demonstrated that cell fate regulation during embryonic development and cell transformation during oncogenesis share common signaling pathways, suggesting that uncontrolled activation of embryonic signaling pathways might drive cell transformation and tumor progression in adult tissues. Here we review our current understanding of how Cripto-1 controls stem cell biology and how it integrates with other major embryonic signaling pathways. Because many cancers are thought to derive from a subpopulation of cancer stem-like cells, which may re-express embryonic genes, Cripto-1 signaling may drive tumor growth through the generation or expansion of tumor initiating cells bearing stem-like characteristics. Therefore, the Cripto-1/Nodal signaling may represent an attractive target for treatment in cancer, leading to the elimination of undifferentiated stem-like tumor initiating cells.

Topics: Animals; Disease Progression; Embryonic Development; Epidermal Growth Factor; Epithelial-Mesenchymal Transition; GPI-Linked Proteins; Humans; Hypoxia; Intercellular Signaling Peptides and Proteins; Membrane Glycoproteins; Neoplasm Proteins; Neoplasms; Neoplastic Stem Cells; Nodal Protein; Receptors, Notch; Signal Transduction; Stem Cells; Wnt Proteins

Topics: Animals; Asparagine; DNA-Binding Proteins; Epidermal Growth Factor; Gene Expression Regulation; Humans; Hydrogen-Ion Concentration; Hydroxylation; Hypoxia; Hypoxia-Inducible Factor 1; Hypoxia-Inducible Factor 1, alpha Subunit; Models, Biological; Nuclear Proteins; Oxygen; Proline; Protein Structure, Tertiary; Transcription Factors; Transcriptional Activation

The aim of the present study was to investigate the underlying mechanism of AS-IV and CCN1 in PAH and to evaluate whether the protective effect of AS-IV against PAH is associated with CCN1 and its related signalling pathway. In vivo, male SD rats were intraperitoneally injected with monocrotaline (MCT, 60 mg/kg) or exposed to hypoxia (10% oxygen) and gavaged with AS-IV (20, 40 and 80 mg/kg/day) to create a PAH model. In vitro, human pulmonary artery endothelial cells (hPAECs) were exposed to hypoxia (3% oxygen) or monocrotaline pyrrole (MCTP, 60 μg/mL) and treated with AS-IV (10, 20 and 40 μM), EGF (10 nM, ERK agonist), small interfering CCN1 (CCN1 siRNA) and recombinant CCN1 protein (rCCN1, 100 ng/mL). We identified the differences in the expression of genes in the lung tissues of PAH rats by proteomics. At the same time, we dynamically detected the expression of CCN1 by Western blot both in vivo and in vitro. The Western blot experimental results showed that the expression of CCN1 increased in the early stage of PAH and decreased in the advanced stage of PAH. The results showed that compared with the control group, MCT- and hypoxia-induced increased the hemodynamic parameters and apoptosis. AS-IV can improve PAH, as characterized by decreased hemodynamic parameters, vascular wall area ratio (WA%), vascular wall thickness ratio (WT%) and α-SMA expression and inhibition of cell apoptosis. Moreover, the improvement of PAH by AS-IV was accompanied by increased CCN1 expression, which activated the ERK1/2 signalling pathway. Meanwhile, CCN1 and p-ERK1/2 were inhibited by siCCN1 and promoted by rCCN1. EGF not only activated the ERK1/2 signalling pathway but also induced the expression of CCN1. In conclusion, AS-IV improves PAH by increasing the expression of CCN1 and activating the ERK1/2 signalling pathway. The results of our study provide a theoretical basis for additional study on the protective effect of AS-IV against PAH.

Topics: Animals; Disease Models, Animal; Endothelial Cells; Epidermal Growth Factor; Familial Primary Pulmonary Hypertension; Humans; Hypertension, Pulmonary; Hypoxia; Male; MAP Kinase Signaling System; Oxygen; Pulmonary Arterial Hypertension; Pulmonary Artery; Rats; Rats, Sprague-Dawley

Chronic wounds depict a silent epidemic challenging medical professionals worldwide. Regenerative medicine uses adipose-derived stem cells (ADSC) in promising new therapies. In this study, platelet lysate (PL) as a xenogen-free substitute for foetal bovine serum (FBS) in ADSC culture was used to create an ADSC secretome containing cytokines for optimal wound healing conditions. The ADSC secretome was tested on keratinocytes for migrational behaviour and viability. Therefore, human ADSC were characterized under FBS (10%) and PL (5% and 10%) substitution, regarding morphology, differentiation, viability, gene and protein expression. ADSC were then cultured in 5% PL and their secretome was used for stimulation of keratinocyte migration and viability. To enhance the effect, ADSC were treated with Epithelial Growth Factor (EGF, 100 ng/mL) and hypoxia (1% O₂). In both PL and FBS groups, ADSC expressed typical stem cell markers. PL induced a significantly higher increase in cell viability compared to FBS substitution. ADSC secretome contained various beneficial proteins which enhance the wound healing capacity of keratinocytes. This could be optimized treating ADSC with hypoxia and EGF. In conclusion, the study shows that ADSC cultivated in 5% PL can effectively support wound healing conditions and can be considered as a promising new therapy for individual treatment of chronic wound disorders.

Topics: Adipose Tissue; Blood Platelets; Cell Culture Techniques; Cell Extracts; Cell Proliferation; Epidermal Growth Factor; Humans; Hypoxia; Keratinocytes; Secretome; Stem Cells

The hallmark of pulmonary hypertension (PH) is vascular remodeling. We have previously shown that human pulmonary microvascular endothelial cells (hPMVEC) respond to hypoxia with epidermal growth factor (EGF) mediated activation of the receptor tyrosine kinase, EGF receptor (EGFR), resulting in arginase-2 (Arg2)-dependent proliferation. We hypothesized that the release of EGF by hPMVEC could result in the proliferation of human pulmonary arterial smooth muscle cells (hPASMC) via activation of EGFR on the hPASMC leading to Arg2 up-regulation. To test this hypothesis, we used conditioned media (CM) from hPMVEC grown either in normoxia (NCM) or hypoxia (HCM). Human PASMC were incubated in normoxia with either HCM or NCM, and HCM caused significant induction of Arg2 and viable cell numbers. When HCM was generated with either an EGF-neutralizing antibody or an EGFR blocking antibody the resulting HCM did not induce Arg2 or increase viable cell numbers in hPASMC. Adding an EGFR blocking antibody to HCM, prevented the HCM-induced increase in Arg2 and viable cell numbers. HCM induced robust phosphorylation of hPASMC EGFR. When hPASMC were transfected with siRNA against EGFR the HCM-induced increase in viable cell numbers was prevented. When hPASMC were treated with the arginase antagonist nor-NOHA, the HCM-induced increase in viable cell numbers was prevented. These data suggest that hypoxic hPMVEC releases EGF, which activates hPASMC EGFR leading to Arg2 protein expression and an increase in viable cell numbers. We speculate that EGF neutralizing antibodies or EGFR blocking antibodies represent potential therapeutics to prevent and/or attenuate vascular remodeling in PH associated with hypoxia.

Topics: Arginase; Cell Hypoxia; Cell Proliferation; Endothelial Cells; Epidermal Growth Factor; ErbB Receptors; Humans; Hypertension, Pulmonary; Hypoxia; Muscle, Smooth, Vascular; Myocytes, Smooth Muscle; Pulmonary Artery; Vascular Remodeling

The pathogenesis of chronic rhinosinusitis (CRS) is largely unknown, but accumulating evidence supports the role of the airway epithelium in its pathophysiology. In our study here, we evaluated whether epidermal growth factor (EGF) regulates a hypoxia-inducible factor 1α (HIF-1α)-microRNA-21 (miR-21)-aquaporin 4 (AQP4) axis in nasal epithelial cells from CRS patients. We found that, compared with normal sinus mucosa, EGF, HIF-1α, and miR-21 were upregulated and AQP4 was downregulated in sinus mucosa from patients with CRS and in a CRS mouse model. It was established that EGF upregulated HIF-1α and miR-21 expression, that HIF-1α regulated miR-21 transcription, and that the AQP4 gene was a target of miR-21. Knockdown of EGF and HIF-1α mRNAs and of miR-21, or overexpression of AQP4 mRNA, inhibited proliferation and promoted apoptosis of hypoxia-exposed human nasal epithelial cells, effects that were associated with reduced levels of α-SMA, fibronectin, and vimentin, as well as promoted caspase-3 activity and E-cadherin levels. In the mouse CRS model, EGF elevation increased in vivo production of inflammatory IL-4 and IFN-γ to promote CRS, which was reversed by AQP4 elevation. Collectively, EGF upregulates HIF-1α and miR-21 expression to inhibit AQP4 expression, thereby promoting the proliferation of nasal epithelial cells and the development of CRS.

Topics: Animals; Aquaporin 4; Epidermal Growth Factor; Humans; Hypoxia; Hypoxia-Inducible Factor 1, alpha Subunit; Mice; MicroRNAs; RNA, Messenger; Sinusitis

Topics: Animals; Epidermal Growth Factor; Hypoxia; Intracellular Signaling Peptides and Proteins; Metabolomics; Proteomics; Signal Transduction; Takifugu; Transforming Growth Factor beta1; Vibrio Infections; Vibrio parahaemolyticus

Glioblastoma multiforme (GBM) is one of the most common and deadly cancers of the central nervous system (CNS). It is characterized by the presence of hypoxic regions, especially in the core, leading to an increase in vascularity. This increased vascularization is driven by the expression of the major angiogenic inducer VEGF and the indirect angiogenic inducer Epidermal growth factor (EGF), which stimulates VEGF expression. In this study, we examine the regulation of VEGF by both hypoxia and the EGF signaling pathway. We also examine the involvement of pathways downstream from EGF signaling, including the mitogen-activated protein kinase/extracellular regulated kinase (MAPK/ERK) pathway and the Phosphatidylinositol-3-kinase/RhoA/C (PI3K/RhoA/C) pathway in this regulation. Our results show that VEGF expression and secretion levels increase following either hypoxia or EGF stimulation, with the two stimuli signaling in parallel. We also observed an increase in ERK and protein kinase B (Akt) phosphorylation, in response to EGF stimulation, with kinetics that correlated with the kinetics of the effect on VEGF. Using pharmacological inhibitors against ERK and PI3K and small interfering RNAs (siRNAs) against RhoA and RhoC, we found that both the ERK and the PI3K/RhoA/C pathways have to cooperate in order to lead to an increase in VEGF expression, downstream from EGF. In response to hypoxia, however, only ERK was involved in the regulation of VEGF. Hypoxia also led to a surprising decrease in the activation of PI3K and RhoA/C. Finally, the decrease in the activation of these Rho-GTPases was found to be mediated through a hypoxia-driven overexpression of the Rho-GTPase GTPase activating protein (GAP), StarD13. Therefore, while under normoxic conditions, EGF stimulates the activation of both the PI3K and the MAPK pathways and the induction of VEGF, in glioblastoma cells, hypoxic conditions lead to the suppression of the PI3K/RhoA/C pathway and an exclusive switch to the MAPK pathway.

Topics: Cell Line, Tumor; Epidermal Growth Factor; Extracellular Signal-Regulated MAP Kinases; Glioblastoma; GTP Phosphohydrolases; GTPase-Activating Proteins; Humans; Hypoxia; MAP Kinase Signaling System; Mitogen-Activated Protein Kinases; Phosphatidylinositol 3-Kinases; Phosphorylation; Rho Factor; Signal Transduction; Vascular Endothelial Growth Factor A

We have previously shown that hypoxia-induced proliferation of human pulmonary microvascular endothelial cells (hPMVEC) depends on arginase II, and that epidermal growth factor receptor (EGFR) is necessary for hypoxic-induction of arginase II. However, it remains unclear how hypoxia activates EGFR-mediated signaling in hPMVEC. We hypothesized that hypoxia results in epidermal growth factor (EGF) production and that EGF binds to EGFR to activate the signaling cascade leading to arginase II induction and proliferation in hPMVEC. We found that hypoxia significantly increased the mRNA levels of EGF, EGFR, and arginase in hPMVEC. Hypoxia significantly increased pEGFR(Tyr845) protein levels and an EGF neutralizing antibody prevented the hypoxic induction of pEGFR. Inhibiting EGFR activation prevented hypoxia-induced arginase II mRNA and protein induction. Treatment of hPMVEC with exogenous EGF resulted in greater levels of arginase II protein both in normoxia and hypoxia. An EGF neutralizing antibody diminished hypoxic induction of arginase II and resulted in fewer viable cells in hPMVEC. Similarly, siRNA against EGF prevented hypoxic induction of arginase II and resulted in fewer viable cells. Finally, conditioned media from hypoxic hPMVEC induced proliferation in human pulmonary artery smooth muscle cells (hPASMC), however, conditioned media from a group of hypoxic hPMVEC in which EGF were knocked down did not promote hPASMC proliferation. These findings demonstrate that hypoxia-induced arginase II expression and cellular proliferation depend on autocrine EGF production leading to EGFR activation in hPMVEC. We speculate that EGF-EGFR signaling may be a novel therapeutic target for pulmonary hypertensive disorders associated with hypoxia.

Topics: Arginase; Cell Hypoxia; Cell Proliferation; Cells, Cultured; Endothelial Cells; Epidermal Growth Factor; ErbB Receptors; Humans; Hypoxia; Microvessels; Myocytes, Smooth Muscle; Pulmonary Artery; RNA, Messenger; Signal Transduction

There are no clinically relevant treatments available that improve function in the growing population of very preterm infants (less than 32 weeks' gestation) with neonatal brain injury. Diffuse white matter injury (DWMI) is a common finding in these children and results in chronic neurodevelopmental impairments. As shown recently, failure in oligodendrocyte progenitor cell maturation contributes to DWMI. We demonstrated previously that the epidermal growth factor receptor (EGFR) has an important role in oligodendrocyte development. Here we examine whether enhanced EGFR signalling stimulates the endogenous response of EGFR-expressing progenitor cells during a critical period after brain injury, and promotes cellular and behavioural recovery in the developing brain. Using an established mouse model of very preterm brain injury, we demonstrate that selective overexpression of human EGFR in oligodendrocyte lineage cells or the administration of intranasal heparin-binding EGF immediately after injury decreases oligodendroglia death, enhances generation of new oligodendrocytes from progenitor cells and promotes functional recovery. Furthermore, these interventions diminish ultrastructural abnormalities and alleviate behavioural deficits on white-matter-specific paradigms. Inhibition of EGFR signalling with a molecularly targeted agent used for cancer therapy demonstrates that EGFR activation is an important contributor to oligodendrocyte regeneration and functional recovery after DWMI. Thus, our study provides direct evidence that targeting EGFR in oligodendrocyte progenitor cells at a specific time after injury is clinically feasible and potentially applicable to the treatment of premature children with white matter injury.

Topics: Administration, Intranasal; Animals; Animals, Newborn; Brain Injuries; Cell Differentiation; Cell Division; Cell Lineage; Cell Survival; Demyelinating Diseases; Disease Models, Animal; Epidermal Growth Factor; ErbB Receptors; Humans; Hypoxia; Infant, Premature, Diseases; Male; Mice; Molecular Targeted Therapy; Oligodendroglia; Regeneration; Signal Transduction; Stem Cells; Time Factors

Pulmonary hypertension (PH) is a life-threatening disease characterized by vascular remodeling and increased pulmonary vascular resistance. Chronic alveolar hypoxia in animals is often used to decipher pathways being regulated in PH. Here, we aimed to investigate whether chronic hypoxia-induced PH in mice can be reversed by reoxygenation and whether possible regression can be used to identify pathways activated during the reversal and development of PH by genome-wide screening.. Mice exposed to chronic hypoxia (21 days, 10% O2) were reoxygenated for up to 42 days. Full reversal of PH during reoxygenation was evident by normalized right ventricular pressure, right heart hypertrophy, and muscularization of small pulmonary vessels. Microarray analysis from these mice revealed s-adenosylmethionine decarboxylase 1 (AMD-1) as one of the most downregulated genes. In situ hybridization localized AMD-1 in pulmonary vessels. AMD-1 silencing decreased the proliferation of pulmonary arterial smooth muscle cells and diminished phospholipase Cγ1 phosphorylation. Compared with the respective controls, AMD-1 depletion by heterozygous in vivo knockout or pharmacological inhibition attenuated PH during chronic hypoxia. A detailed molecular approach including promoter analysis showed that AMD-1 could be regulated by early growth response 1, transcription factor, as a consequence of epidermal growth factor stimulation. Key findings from the animal model were confirmed in human idiopathic pulmonary arterial hypertension.. Our study indicates that genome-wide screening in mice from a PH model in which full reversal of PH occurs can be useful to identify potential key candidates for the reversal and development of PH. Targeting AMD-1 may represent a promising strategy for PH therapy.

Topics: Adenosylmethionine Decarboxylase; Adult; Aged; Animals; Apoptosis; Cell Proliferation; Cells, Cultured; Disease Models, Animal; Down-Regulation; Early Growth Response Protein 1; Epidermal Growth Factor; Female; Humans; Hypertension, Pulmonary; Hypoxia; Lung; Male; Mice; Mice, Inbred C57BL; Mice, Knockout; Microarray Analysis; Middle Aged; Muscle, Smooth, Vascular; Pulmonary Artery; Signal Transduction

Colorectal cancer (CRC) is characterised by hypoxia, which activates gene transcription through hypoxia-inducible factors (HIF), as well as by expression of epidermal growth factor (EGF) and EGF receptors, targeting of which has been demonstrated to provide therapeutic benefit in CRC. Although EGF has been demonstrated to induce expression of angiogenic mediators, potential interactions in CRC between EGF-mediated signalling and the hypoxia/HIF pathway remain uncharacterised.. PCR-based profiling was applied to identify angiogenic genes in Caco-2 CRC cells regulated by hypoxia, the hypoxia mimetic dimethyloxallylglycine (DMOG) and/or EGF. Western blotting was used to determine the role of HIF-1alpha, HIF-2alpha and MAPK cell signalling in mediating the angiogenic responses.. We identified a total of 9 angiogenic genes, including angiopoietin-like (ANGPTL) 4, ephrin (EFNA) 3, transforming growth factor (TGF) β1 and vascular endothelial growth factor (VEGF), to be upregulated in a HIF dependent manner in Caco-2 CRC cells in response to both hypoxia and the hypoxia mimetic dimethyloxallylglycine (DMOG). Stimulation with EGF resulted in EGFR tyrosine autophosphorylation, activation of p42/p44 MAP kinases and stabilisation of HIF-1α and HIF-2α proteins. However, expression of 84 angiogenic genes remained unchanged in response to EGF alone. Crucially, addition of DMOG in combination with EGF significantly increased expression of a further 11 genes (in addition to the 9 genes upregulated in response to either DMOG alone or hypoxia alone). These additional genes included chemokines (CCL-11/eotaxin-1 and interleukin-8), collagen type IV α3 chain, integrin β3 chain, TGFα and VEGF receptor KDR.. These findings suggest that although EGFR phosphorylation activates the MAP kinase signalling and promotes HIF stabilisation in CRC, this alone is not sufficient to induce angiogenic gene expression. In contrast, HIF activation downstream of hypoxia/DMOG drives expression of genes such as ANGPTL4, EFNA3, TGFβ1 and VEGF. Finally, HIF activation synergises with EGF-mediated signalling to additionally induce a unique sub-group of candidate angiogenic genes. Our data highlight the complex interrelationship between tumour hypoxia, EGF and angiogenesis in the pathogenesis of CRC.

Topics: Cell Hypoxia; Cell Line, Tumor; Colorectal Neoplasms; Epidermal Growth Factor; ErbB Receptors; Gene Expression Regulation, Neoplastic; Humans; Hypoxia; Hypoxia-Inducible Factor 1; Neovascularization, Pathologic; Transcriptome

Hypoxia has been long-time acknowledged as major cancer-promoting microenvironment. In such an energy-restrictive condition, post-transcriptional mechanisms gain importance over the energy-expensive gene transcription machinery. Here we show that the onset of hypoxia-induced cancer stem cell features requires the beta-catenin-dependent post-transcriptional up-regulation of CA9 and SNAI2 gene expression. In response to hypoxia, beta-catenin moves from the plasma membrane to the cytoplasm where it binds and stabilizes SNAI2 and CA9 mRNAs, in cooperation with the mRNA stabilizing protein HuR. We also provide evidence that the post-transcriptional activity of cytoplasmic beta-catenin operates under normoxia in basal-like/triple-negative breast cancer cells, where the beta-catenin knockdown suppresses the stem cell phenotype in vitro and tumor growth in vivo. In such cells, we unravel the generalized involvement of the beta-catenin-driven machinery in the stabilization of EGF-induced mRNAs, including the cancer stem cell regulator IL6. Our study highlights the crucial role of post-transcriptional mechanisms in the maintenance/acquisition of cancer stem cell features and suggests that the hindrance of cytoplasmic beta-catenin function may represent an unprecedented strategy for targeting breast cancer stem/basal-like cells.

Topics: 3' Untranslated Regions; Animals; Antigens, Neoplasm; beta Catenin; Breast Neoplasms; Carbonic Anhydrase IX; Carbonic Anhydrases; Cell Dedifferentiation; Cell Line, Tumor; Cell Nucleus; Cell Proliferation; Cell Survival; Disease Models, Animal; ELAV Proteins; Epidermal Growth Factor; Female; Gene Expression; Gene Knockdown Techniques; Heterografts; Humans; Hypoxia; Hypoxia-Inducible Factor 1, alpha Subunit; Mice; Neoplastic Stem Cells; Phenotype; Ribosome Subunits, Small, Eukaryotic; RNA Processing, Post-Transcriptional; RNA Stability; RNA, Messenger; Snail Family Transcription Factors; Transcription Factors; Transcription, Genetic; Triple Negative Breast Neoplasms

Carbonic anhydrase IX (CAIX) is a zinc metalloenzyme that catalyzes the reversible hydration of CO(2). CAIX is overexpressed in many types of cancer, including breast cancer, but is most frequently absent in corresponding normal tissues. CAIX expression is strongly induced by hypoxia and is significantly associated with tumor grade and poor survival. Herein, we show that hypoxia induces a significant increase in CAIX protein in MDA-MB-231 breast cancer cells. Using a unique mass spectrophotometric assay, we demonstrate that CAIX activity in plasma membranes isolated from MDA-MB-231 is correlated with CAIX content. We also show that CAIX exists predominantly as a dimeric, high-mannose N-linked glycoprotein. While there is some evidence that the dimeric form resides specifically in lipid rafts, our data do not support this hypothesis. EGF, alone, did not affect the distribution of CAIX into lipid rafts. However, acute EGF treatment in the context of hypoxia increased the amount of CAIX in lipid rafts by about 5-fold. EGF did not stimulate tyrosine phosphorylation of CAIX, although EGFR and down-stream signaling pathways were activated by EGF. Interestingly, hypoxia activated Akt independent of EGF action. Together, these data demonstrate that the active form of CAIX in the MDA-MB-231 breast cancer cell line is dimeric but that neither lipid raft localization nor phosphorylation are likely required for its dimerization or activity.

Topics: Antigens, Neoplasm; Breast Neoplasms; Carbonic Anhydrase IX; Carbonic Anhydrases; Cell Line, Tumor; Epidermal Growth Factor; ErbB Receptors; Female; Glycosylation; Humans; Hypoxia; Immunoblotting; Membrane Microdomains; Phosphorylation; Protein Multimerization; Proto-Oncogene Proteins c-akt

The role of ErbB4 and ErbB2 in the heart of adult mammals is well established. The heart also expresses ErbB1 (the epidermal growth factor (EGF) receptor), but this receptor has received less attention. We studied the effect of EGF on the response of isolated mouse heart to low-flow ischemia and reperfusion. Reducing perfusate flow to 10% for 30 min resulted in an increase in anaerobic metabolism and the leakage of lactate dehydrogenase during reperfusion. In addition, left ventricle +dP/dt and developed pressure were depressed (20-25%) during reperfusion. The addition of EGF 5 min before and throughout the ischemic period prevented the increase in anaerobic metabolism and the leakage of intracellular lactate dehydrogenase during reperfusion. EGF improved both +dP/dt and developed pressure during ischemia and prevented the decrease in dP/dt during reperfusion. To determine whether the effect of EGF on cell integrity depends on its effect on contractility, we studied nonbeating isolated myocytes. In these cells, anoxia and reoxygenation reduced cell viability by nearly 25%. EGF prevented such a decrease. Our results indicate that, like ErbB4 and ErbB2, ErbB1 also has an important role in the heart of adult animals.

Topics: Animals; Epidermal Growth Factor; Heart; Hypoxia; Mice; Myocardial Reperfusion Injury; Rats; Reperfusion

While intraventricular administration of epidermal growth factor (EGF) expands the proliferation of neural stem/progenitor cells in the subventricular zone (SVZ), overexpression of brain-derived neurotrophic factor (BDNF) is particularly effective in enhancing striatal neurogenesis. We assessed the induction of striatal neurogenesis and consequent functional recovery after chronic infusion of BDNF and EGF in an adult animal model of neonatal hypoxic-ischemic (HI) brain injury. Permanent brain damage was induced in CD-1 (ICR) mice (P7) by applying the ligation of unilateral carotid artery and hypoxic condition. At 6 weeks of age, the mice were randomly assigned to groups receiving a continuous 2-week infusion of one of the following treatments into the ventricle: BDNF, EGF, BDNF/EGF, or phosphate buffered saline (PBS). Two weeks after treatment, immunohistochemical analysis revealed an increase in the number of BrdU(+) cells in the SVZ and striata of BDNF/EGF-treated mice. The number of new neurons co-stained with BrdU and betaIII-tubulin was also significantly increased in the neostriata of BDNF/EGF-treated mice, compared with PBS group. In addition, the newly generated cells were expressed as migrating neuroblasts labeled with PSA-NCAM or doublecortin in the SVZ and the ventricular side of neostriata. The new striatal neurons were also differentiated as mature neurons co-labeled with BrdU(+)/NeuN(+). When evaluated post-surgical 8 weeks, BDNF/EGF-treated mice exhibited significantly longer rotarod latencies at constant speed (48 rpm) and under accelerating condition (4-80 rpm), relative to PBS and untreated controls. In the forelimb-use asymmetry test, BDNF/EGF-treated mice showed significant improvement in the use of the contralateral forelimb. In contrast, this BDNF/EGF-associated functional recovery was abolished in mice receiving a co-infusion of 2% cytosine-b-d-arabinofuranoside (Ara-C), a mitotic inhibitor. Induction of striatal neurogenesis by the intraventricular administration of BDNF and EGF promoted functional recovery in an adult animal model of neonatal HI brain injury. The effect of Ara-C to completely block functional recovery indicates that the effect may be the result of newly generated neurons. Therefore, this treatment may offer a promising strategy for the restoration of motor function for adults with cerebral palsy (CP).

Topics: Animals; Ataxia; Brain Damage, Chronic; Brain-Derived Neurotrophic Factor; Carotid Arteries; Cerebral Palsy; Corpus Striatum; Cytarabine; Disease Models, Animal; Drug Evaluation, Preclinical; Epidermal Growth Factor; Forelimb; Hemiplegia; Hypoxia; Hypoxia-Ischemia, Brain; Infusions, Intraventricular; Ligation; Mice; Mice, Inbred ICR; Neurogenesis; Random Allocation; Recovery of Function

We have previously demonstrated that enterally administered heparin-binding EGF-like growth factor (HB-EGF) produced in Escherichia coli decreases the incidence and severity of intestinal injury in a neonatal rat model of necrotizing enterocolitis (NEC). In preparation for upcoming human clinical trials, large-scale production of HB-EGF according to Good Manufacturing Practice (GMP) has been successfully accomplished using a Pichia pastoris yeast system. The current studies used a neonatal rat model of NEC to elucidate several important preclinical characteristics of HB-EGF therapy. We found that enteral administration of HB-EGF (800 microg/kg/dose) four times a day effectively reduced the incidence and severity of NEC, that Pichia-derived HB-EGF was not significantly different from E. coli-derived HB-EGF in preventing NEC, that EGF was not superior to HB-EGF in preventing NEC, and that prophylactic administration of HB-EGF added to formula starting with the first feed or 12 h later significantly reduced the incidence of NEC, with no change in the incidence of NEC noted if HB-EGF was added to the formula starting 24, 48, or 72 h after birth. Thus, large-scale production of GMP-grade HB-EGF in Pichia pastoris yeast produces a biologically active molecule suitable for human clinical trials.

Topics: Animals; Animals, Newborn; Disease Models, Animal; Dose-Response Relationship, Drug; Drug Administration Schedule; Enteral Nutrition; Enterocolitis, Necrotizing; Epidermal Growth Factor; Escherichia coli; Gastrointestinal Agents; Heparin-binding EGF-like Growth Factor; Humans; Hypoxia; Intercellular Signaling Peptides and Proteins; Intestines; Lipopolysaccharides; Pichia; Rats; Rats, Sprague-Dawley; Recombinant Proteins; Severity of Illness Index; Time Factors

Cripto-1 is a membrane-bound protein that is highly expressed in embryonic stem cells and in human tumors. In the present study, we investigated the effect of low levels of oxygen, which occurs naturally in rapidly growing tissues, on Cripto-1 expression in mouse embryonic stem (mES) cells and in human embryonal carcinoma cells. During hypoxia, Cripto-1 expression levels were significantly elevated in mES cells and in Ntera-2 or NCCIT human embryonal carcinoma cells, as compared with cells growing with normal oxygen levels. The transcription factor hypoxia-inducible factor-1alpha directly regulated Cripto-1 expression by binding to hypoxia-responsive elements within the promoter of mouse and human Cripto-1 genes in mES and NCCIT cells, respectively. Furthermore, hypoxia modulated differentiation of mES cells by enhancing formation of beating cardiomyocytes as compared with mES cells that were differentiated under normoxia. However, hypoxia failed to induce differentiation of mES cells into cardiomyocytes in the absence of Cripto-1 expression, demonstrating that Cripto-1 is required for hypoxia to fully differentiate mES cells into cardiomyocytes. Finally, cardiac tissue samples derived from patients who had suffered ischemic heart disease showed a dramatic increase in Cripto-1 expression as compared with nonischemic heart tissue samples, suggesting that hypoxia may also regulate Cripto-1 in vivo.

Topics: Animals; Biomarkers; Cell Differentiation; Cell Line; Embryonic Stem Cells; Epidermal Growth Factor; Heart; Humans; Hypoxia; Hypoxia-Inducible Factor 1, alpha Subunit; Membrane Glycoproteins; Mice; Mice, Knockout; Myocardium; Myocytes, Cardiac; Neoplasm Proteins; Promoter Regions, Genetic; Response Elements; RNA, Small Interfering; Signal Transduction; Swine

The physiological adaptations of the neonatal rat to hypoxia from birth include changes in gastrointestinal function and intermediary metabolism. We hypothesized that the hypoxic lactating dam would exhibit alterations in mammary gland function leading to changes in the concentration of milk peptides that are important in neonatal gastrointestinal development. The present study assessed the effects of chronic hypoxia on peptides produced by the mammary glands and present in milk. Chronic hypoxia decreased the concentration of epidermal growth factor (EGF) in expressed milk and pup stomach contents and decreased maternal mammary gland EGF mRNA. The concentration of parathyroid hormone-related protein (PTHrp) was unchanged in milk and decreased in pup stomach contents; however, mammary PTHLH mRNA was increased by hypoxia. There was a significant increase in adiponectin concentrations in milk from hypoxic dams. Chronic hypoxia decreased maternal body weight, and pair feeding normoxic dams an amount of food equivalent to hypoxic dam food intake decreased body weight to an equivalent degree. Decreased food intake did not affect the expression of EGF, PTHLH, or LEP mRNA in mammary tissue. The results indicated that chronic hypoxia modulated mammary function independently of hypoxia-induced decreases in maternal food intake. Decreased EGF and increased adiponectin concentrations in milk from hypoxic dams likely affect the development of neonatal intestinal function.

Topics: Adiponectin; Animals; Animals, Suckling; Eating; Epidermal Growth Factor; Female; Hypoxia; Lactation; Leptin; Male; Mammary Glands, Animal; Milk; Parathyroid Hormone-Related Protein; Postpartum Period; Rats; Rats, Sprague-Dawley; RNA, Messenger

Hypoxia is thought to be a stimulus for the excessive proliferation of vascular smooth muscle cells (VSMC) that contributes to pulmonary hypertension, but the mechanisms involved are unknown. Here we tested whether hypoxia-inducible factor 1-alpha (HIF-1alpha), a master regulator of the transcriptional response to hypoxia, is involved in the enhanced mitogen-induced proliferative responses of hypoxic VSMC. Exposure to moderate hypoxia (5% O(2)) enhanced the proliferative responses of human pulmonary artery SMC (HPASMC) to mitogens including platelet-derived growth factor (PDGF), fibroblast growth factor 2 (FGF-2), and epidermal growth factor (EGF), compared with those in normoxia (20% O(2)). Moderate hypoxia elicited increased cellular HIF-1alpha levels, shown by Western blot analysis, and also enhanced PDGF-, FGF-2-, and EGF-induced expression of HIF-1alpha. Knockdown of HIF-1alpha or HIF-1beta levels in HPASMC with specific small interfering RNAs inhibited FGF-2-stimulated proliferation of HPASMC incubated in either 5% or 20% O(2) but failed to inhibit the comitogenic effect of hypoxia. Knockdown of HIF-1alpha similarly inhibited PDGF-stimulated proliferation, whereas HIF-2alpha knockdown had no effect on HPASMC proliferation. Knockdown of HIF-1alpha expression also inhibited growth factor-induced expression of cyclin A. We conclude that HIF-1alpha promotes proliferative responses of human VSMC to FGF-2, PDGF, and EGF by mechanisms that may involve HIF-1-dependent expression of cyclin A, but HIF is apparently not crucial to the enhancement of FGF-2-, PDGF-, and EGF-induced proliferation of VSMC that occurs during hypoxia.

Topics: Aryl Hydrocarbon Receptor Nuclear Translocator; Basic Helix-Loop-Helix Transcription Factors; Blotting, Western; Cell Proliferation; Cells, Cultured; Cyclin A; Epidermal Growth Factor; Fibroblast Growth Factor 2; Humans; Hypoxia; Hypoxia-Inducible Factor 1, alpha Subunit; Mitogens; Muscle, Smooth, Vascular; Platelet-Derived Growth Factor; Pulmonary Artery; RNA Interference; RNA, Small Interfering; Transfection

Non-small cell lung cancer (NSCLC) expresses a particularly aggressive metastatic phenotype, and patients with this disease have a poor prognosis. CXC chemokine receptor 4 (CXCR4) is a cell surface receptor that has been shown to mediate the metastasis of many solid tumors including lung, breast, kidney, and prostate. In addition, overexpression of the epidermal growth factor receptor (EGFR) is associated with the majority of NSCLC and has been implicated in the process of malignant transformation by promoting cell proliferation, cell survival, and motility. Here we show for the first time that activation of the EGFR by EGF increases CXCR4 expression and the migratory capacity of NSCLC cells. Furthermore, many solid tumors are associated with low oxygen tension, and when NSCLC cells were cultured with EGF under hypoxic conditions, CXCR4 expression was dramatically enhanced. A molecular analysis of these events indicated that augmented CXCR4 expression was regulated by the phosphatidylinositol 3-kinase/PTEN/AKT/mammalian target of rapamycin signal transduction pathway, activation of hypoxia inducible factor (HIF) 1alpha, and ultimately HIF-1-dependent transcription of the CXCR4 gene. Thus, a combination of low oxygen tension and overexpression of EGFR within the primary tumor of NSCLC may provide the microenvironmental signals necessary to upregulate CXCR4 expression and promote metastasis.

Topics: Blotting, Western; Carcinoma, Non-Small-Cell Lung; Cell Line, Tumor; Cell Proliferation; Cell Separation; Cell Survival; Chemokine CXCL12; Chemokines, CXC; Chemotaxis; Dose-Response Relationship, Drug; Epidermal Growth Factor; Flow Cytometry; Humans; Hypoxia; Hypoxia-Inducible Factor 1, alpha Subunit; Lung Neoplasms; Neoplasm Metastasis; Oxygen; Phosphatidylinositol 3-Kinases; Phosphoric Monoester Hydrolases; Promoter Regions, Genetic; Protein Kinases; Protein Serine-Threonine Kinases; Proto-Oncogene Proteins; Proto-Oncogene Proteins c-akt; PTEN Phosphohydrolase; Receptors, CXCR4; RNA, Messenger; Signal Transduction; Sirolimus; TOR Serine-Threonine Kinases; Transcription Factors; Transcription, Genetic; Transcriptional Activation; Transfection; Tumor Suppressor Proteins; Up-Regulation

Changes in the redox equilibrium of cells influence a host of cell functions. Alterations in the redox equilibrium are precipitated by changing either the glutathione/glutathione-disulfide ratio (GSH/GSSG) and/or the reduced/oxidized thioredoxin ratio. Redox-sensitive green fluorescent proteins (GFP) allow real time visualization of the oxidation state of the indicator. Ratios of fluorescence from excitation at 400 and 490 nm indicate the extent of oxidation and thus the redox potential while canceling out the amount of indicator and the absolute optical sensitivity. Because the indicator is genetically encoded, it can be targeted to specific proteins or organelles of interest and expressed in a wide variety of cells and organisms. We evaluated roGFP1 (GFP with mutations C48S, S147C, and Q204C) and roGFP2 (the same plus S65T) with physiologically or toxicologically relevant oxidants both in vitro and in living mammalian cells. Furthermore, we investigated the response of the redox probes under physiological redox changes during superoxide bursts in macrophage cells, hyperoxic and hypoxic conditions, and in responses to H(2)O(2)-stimulating agents, e.g. epidermal growth factor and lysophosphatidic acid.

Topics: Cloning, Molecular; Dose-Response Relationship, Drug; Epidermal Growth Factor; Flow Cytometry; Glutathione; Glutathione Disulfide; Green Fluorescent Proteins; HeLa Cells; HL-60 Cells; Humans; Hydrogen Peroxide; Hypoxia; Luminescent Proteins; Lysine; Lysophospholipids; Magnetic Resonance Spectroscopy; Mutation; Oxidants; Oxidation-Reduction; Oxygen; Spectrometry, Fluorescence; Superoxides; Time Factors; Xanthine Oxidase

Hypoxia, frequently found in the center of solid tumor, is associated with resistance to chemotherapy by activation of signaling pathways that regulate cell pro-liferation, angiogenesis, and apoptosis. We determined whether hypoxia can increase the resistance of human pancreatic carcinoma cells to gemcitabine-induced apoptosis by activation of phosphatidylinositol 3'-kinase (PI3K)/Akt, MEK/mitogen-activated protein kinase (extracellular signal-regulated kinase) [MAPK(Erk) kinase (MEK)], and nuclear factor kappa B (NF-kappa B) signaling pathways.. We evaluated the phosphorylation of Akt and MAPK(Erk), DNA binding activity of NF-kappa B, and apoptosis induced by gemcitabine in L3.6pl human pancreatic cancer cells under normoxic and hypoxic conditions. We then examined the effects of the PI3K inhibitor LY294002, MEK inhibitor U0126, and the epidermal growth factor receptor tyrosine kinase inhibitor PKI 166 on these signaling pathways and induction of apoptosis.. Hypoxic conditions increased phosphorylation of Akt and MAPK(Erk) and NF-kappa B DNA binding activity in L3.6pl cells. The activation of Akt and NF-kappa B was prevented by LY294002, whereas the activity of MAPK(Erk), but not NF-kappa B, was inhibited by U0126. The increased activation of Akt, NF-kappa B, and MAPK(Erk) was inhibited by PKI 166. Under hypoxic conditions, L3.6pl cells were resistant to apoptosis induced by gemcitabine. The addition of LY294002 or PKI 166 abrogated cell resistance to gemcitabine, whereas U0126 only partially decreased this resistance.. These data demonstrate that hypoxia can induce resistance of pancreatic cancer cells to gemcitabine mainly through the PI3K/Akt/NF-kappa B pathways and partially through the MAPK(Erk) signaling pathway. Because PKI 166 prevented the activation of PI3K/Akt/NF-kappa B and MAPK(Erk) pathways, the combination of this tyrosine kinase inhibitor with gemcitabine should be an effective therapy for pancreatic cancer.

Topics: Antimetabolites, Antineoplastic; Antineoplastic Agents; Apoptosis; Blotting, Western; Butadienes; Cell Division; Cell Line, Tumor; Chromones; Deoxycytidine; Dose-Response Relationship, Drug; Enzyme Inhibitors; Epidermal Growth Factor; ErbB Receptors; Gemcitabine; Humans; Hypoxia; Mitogen-Activated Protein Kinases; Morpholines; Neovascularization, Pathologic; NF-kappa B; Nitriles; Oxygen; Pancreatic Neoplasms; Phosphatidylinositol 3-Kinases; Phosphorylation; Protein-Tyrosine Kinases; Pyrimidines; Pyrroles; Signal Transduction; Sp1 Transcription Factor; Time Factors; Tyrosine

Tumor growth is accelerated by induction of angiogenesis regulated by many cytokines and growth factors. In a tumor mass, various angiogenic factors and their receptors are simultaneously expressed and the overlapped expressions of various factors may contribute to the aggressive growth of tumor. However, the possible combined effect and mechanism of growth factors involved in angiogenesis are still under investigated. Insulin-like growth factor-II (IGF-II) has been identified as an angiogenic factor and highly expressed in solid tumors. Here we demonstrated that another angiogenic factor, epidermal growth factor (EGF), synergistically induced the angiogenic activity when co-treated with IGF-II in vivo. We performed mouse Matrigel plug assay. Cotreatment of IGF-II and EGF resulted in a significant induction of functional new vessels in mouse Matrigel plug more than additive amount of vessels induced by each growth factor. However, synergism of these two factors was not found in in vitro angiogenic assays, i.e., in migration and proliferation assays. The metalloproteinase-2 (MMP-2) protein level was enhanced by co-treatment of IGF-II and EGF, similar to that of individual treatment of them or PMA or bFGF. EGF down-regulated hypoxia-induced IGF-II binding protein-3 (IGFBP-3), which may contribute to the enhancement of free IGF-II accessibility to its receptors in vivo. Moreover, the combination of IGF-II with EGF significantly induced bFGF mRNA level, a potent angiogenic molecule, which may also contribute to synergistic effect in vivo. These results suggest that IGF-II and EGF may synergistically cooperate to induce angiogenesis in vivo by indirect mechanisms, i.e., synergistic induction of another angiogenic factor and modulation of IGF-II's bioavailability.

Topics: Angiogenesis Inducing Agents; Animals; Blood Vessels; Carcinoma, Hepatocellular; Cell Movement; Cell Proliferation; Chick Embryo; Collagen; Drug Combinations; Drug Synergism; Drug Therapy, Combination; Endothelium, Vascular; Epidermal Growth Factor; Fibroblast Growth Factor 2; Humans; Hypoxia; Insulin-Like Growth Factor Binding Protein 3; Insulin-Like Growth Factor II; Laminin; Liver Neoplasms; Male; Matrix Metalloproteinase 2; Mice; Mice, Inbred C57BL; Neoplasm Invasiveness; Proteoglycans; RNA, Messenger; Tumor Cells, Cultured; Umbilical Veins

Bronchioloalveolar carcinoma (BAC), a form of pulmonary adenocarcinoma, presents unique clinical features, such as endobronchial spread and bronchorrhea in advanced stages. The prognosis for BAC patients in advanced stages is poor, as is the case for patients with other non-small-cell lung cancer (NSCLC) types, because of low susceptibility to conventional chemotherapy. Recently, an orally active, selective epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor (EGFR-TKI), ZD1839 ("Iressa"), has been investigated in phase II clinical studies (IDEAL 1 and IDEAL 2) as monotherapy against chemotherapy-refractory NSCLC, and provided clinically significant antitumor activity. In this study, we examined the therapeutic efficiency of ZD1839 in chemotherapy-refractory BAC patients with bronchorrhea. Two female BAC patients with bronchorrhea were treated once daily with ZD1839 (250 mg/day). In both cases, serous sputum production was dramatically reduced within 3 days of starting the treatment, and hypoxia and radiographic signs of bilateral lung consolidation were visibly improved within 7 days. Following more than 8 months of treatment, no evidence of recurrence or severe adverse events has been observed. These results suggest that this selective EGFR-TKI, ZD1839, may be a powerful agent for treatment of chemotherapy-refractory BAC patients with bronchorrhea.

Topics: Adenocarcinoma, Bronchiolo-Alveolar; Aged; Antineoplastic Agents; Drug Resistance, Neoplasm; Epidermal Growth Factor; ErbB Receptors; Female; Gefitinib; Humans; Hypoxia; Lung Neoplasms; Middle Aged; Quinazolines; Radiography; Sputum

Hypoxic regions within solid tumors are often resistant to chemotherapy and radiation. BNIP3 (Bcl-2/E1B 19 kDa interacting protein) is a proapoptotic member of the Bcl-2 family that is expressed in hypoxic regions of tumors. During hypoxia, BNIP3 expression is increased in many cell types and upon forced overexpression BNIP3 induces cell death. Herein, we have demonstrated that blockage of hypoxia-induced BNIP3 expression using antisense oligonucleotides against BNIP3 or blockage of BNIP3 function through expression of a mutant form of BNIP3 inhibits hypoxia-induced cell death in human embryonic kidney 293 cells. We have also determined that hypoxia-mediated BNIP3 expression is regulated by the transcription factor, hypoxia-inducible factor-1alpha (HIF-1alpha) in human epithelial cell lines. Furthermore, HIF-1alpha directly binds to a consensus HIF-1alpha-responsive element (HRE) in the human BNIP3 promoter that upon mutation of this HRE site eliminates the hypoxic responsiveness of the promoter. Since BNIP3 is expressed in hypoxic regions of tumors but fails to induce cell death, we determined whether growth factors block BNIP3-induced cell death. Treatment of the breast cancer cell line MCF-7 cells with epidermal growth factor (EGF) or insulin-like growth factor effectively protected these cells from BNIP3-induced cell death. Furthermore, inhibiting EGF receptor signaling using antibodies against ErbB2 (Herceptin) resulted in increased hypoxia-induced cell death in MCF-7 cells. Taken together, BNIP3 plays a role in hypoxia-induced cell death in human epithelial cells that could be circumvented by growth factor signaling.

Topics: Acridine Orange; Animals; Apoptosis; beta-Galactosidase; Blotting, Western; Cell Death; Cell Division; Cell Line; CHO Cells; Cricetinae; Epidermal Growth Factor; Epithelial Cells; Fluorescent Dyes; Genes, Dominant; Genes, Reporter; Humans; Hypoxia; Hypoxia-Inducible Factor 1, alpha Subunit; Insulin-Like Growth Factor I; Membrane Proteins; Microscopy, Electron; Mutation; Oligonucleotides, Antisense; Promoter Regions, Genetic; Protein Structure, Tertiary; Proto-Oncogene Proteins; Signal Transduction; Time Factors; Transcription Factors; Transfection; Trypan Blue; Tumor Cells, Cultured; Tumor Suppressor Proteins

The high-affinity 67-kd laminin receptor (67LR) is expressed by proliferating endothelial cells during retinal neovascularization. The role of 67LR has been further examined experimentally by administration of selective 67LR agonists and antagonists in a murine model of proliferative retinopathy. These synthetic 67LR ligands have been previously shown to stimulate or inhibit endothelial cell motility in vitro without any direct effect on proliferation. In the present study, a fluorescently labeled 67LR antagonist (EGF(33-42)) was injected intraperitoneally into mice and its distribution in the retina was assessed by confocal scanning laser microscopy. Within 2 hours this peptide was localized to the retinal vasculature, including preretinal neovascular complexes, and a significant amount had crossed the blood retinal barrier. For up to 24 hours postinjection, the peptide was still present in the retinal vascular walls and, to a lesser extent, in the neural retina. Non-labeled EGF(33-42) significantly inhibited pre-retinal neovascularization in comparison to controls treated with phosphate-buffered saline or scrambled peptide (P < 0.0001). The agonist peptide (Lam beta 1(925-933)) also significantly inhibited proliferative retinopathy; however, it caused a concomitant reduction in retinal ischemia in this model by promoting significant revascularization of the central retina (P < 0.001). Thus, 67LR appears to be an important target receptor for the modulation of retinal neovascularization. Agonism of this receptor may be valuable in reducing the hypoxia-stimulated release of angiogenic growth factors which drives retinal angiogenesis.

Topics: Animals; Epidermal Growth Factor; Hypoxia; Ischemia; Laminin; Mice; Mice, Inbred C57BL; Molecular Weight; Neovascularization, Pathologic; Peptide Fragments; Receptors, Laminin; Retinal Diseases; Retinal Vessels

In various cell types, the neuro- and endocrine peptide somatostatin induces inhibitory and anti-secretory effects. Since somatostatin receptors, especially of the subtype sst2A, are constantly over-expressed in gliomas, we investigated the influence of somatostatin and the receptor subtype-selective peptide/non-peptide agonists octreotide and L-054,522 on the secretion of the most important angiogenesis factor produced by gliomas, vascular endothelial growth factor (VEGF). Cultivated cells from solid human gliomas of different stages and glioma cell lines secreted variable amounts of VEGF, which could be lowered to 25% to 80% by co-incubation with somatostatin or sst2-selective agonists (octreotide and L-054,522). These effects were dose-dependent at nanomolar concentrations. Stimulation with different growth factors (EGF, bFGF) or hypoxia considerably increased VEGF production over basal levels. Growth factor-induced VEGF synthesis could be suppressed to <50% by co-incubation with somatostatin or an sst2-selective agonist; this was less pronounced in hypoxia-induced VEGF synthesis. The effects were detected at the protein and mRNA levels. These experiments indicate a potent anti-secretory action of somatostatin or sst2 agonists on human glioma cells that may be useful for inhibiting angiogenesis in these tumors.

Topics: Antineoplastic Agents, Hormonal; Benzimidazoles; Blotting, Northern; Brain Neoplasms; Cells, Cultured; DNA; Dose-Response Relationship, Drug; Endothelial Growth Factors; Epidermal Growth Factor; Fibroblast Growth Factor 2; Glioma; Hormones; Humans; Hypoxia; Indoles; Lymphokines; Octreotide; Peptides; Reverse Transcriptase Polymerase Chain Reaction; RNA, Messenger; Somatostatin; Tumor Cells, Cultured; Vascular Endothelial Growth Factor A; Vascular Endothelial Growth Factors

Dysregulated signal transduction from receptor tyrosine kinases to phosphatidylinositol 3-kinase (PI3K), AKT (protein kinase B), and its effector FKBP-rapamycin-associated protein (FRAP) occurs via autocrine stimulation or inactivation of the tumor suppressor PTEN in many cancers. Here we demonstrate that in human prostate cancer cells, basal-, growth factor-, and mitogen-induced expression of hypoxia-inducible factor 1 (HIF-1) alpha, the regulated subunit of the transcription factor HIF-1, is blocked by LY294002 and rapamycin, inhibitors of PI3K and FRAP, respectively. HIF-1-dependent gene transcription is blocked by dominant-negative AKT or PI3K and by wild-type PTEN, whereas transcription is stimulated by constitutively active AKT or dominant-negative PTEN. LY294002 and rapamycin also inhibit growth factor- and mitogen-induced secretion of vascular endothelial growth factor, the product of a known HIF-1 target gene, thus linking the PI3K/PTEN/AKT/FRAP pathway, HIF-1, and tumor angiogenesis. These data indicate that pharmacological agents that target PI3K, AKT, or FRAP in tumor cells inhibit HIF-1alpha expression and that such inhibition may contribute to therapeutic efficacy.

Topics: Carrier Proteins; Chromones; Culture Media, Serum-Free; DNA-Binding Proteins; Endothelial Growth Factors; Enzyme Inhibitors; Enzyme-Linked Immunosorbent Assay; Epidermal Growth Factor; Humans; Hypoxia; Hypoxia-Inducible Factor 1; Hypoxia-Inducible Factor 1, alpha Subunit; Immunophilins; Lymphokines; Male; Morpholines; Neovascularization, Pathologic; Nuclear Proteins; Phosphatidylinositol 3-Kinases; Phosphoinositide-3 Kinase Inhibitors; Phosphoric Monoester Hydrolases; Phosphotransferases (Alcohol Group Acceptor); Prostatic Neoplasms; Protein Serine-Threonine Kinases; Proto-Oncogene Proteins; Proto-Oncogene Proteins c-akt; PTEN Phosphohydrolase; Signal Transduction; Tetradecanoylphorbol Acetate; TOR Serine-Threonine Kinases; Transcription Factors; Tumor Cells, Cultured; Tumor Suppressor Proteins; Vascular Endothelial Growth Factor A; Vascular Endothelial Growth Factors

The neuronal expression of mRNA of heparin-binding epidermal growth factor-like growth factor (HB-EGF) was investigated in immature rat brains. Two rat models were used in this study. One was a hypoxic/ischemic (HI) brain injury model, and the other was an N-methyl-d-aspartate (NMDA) intracerebral injection model. The former model was made by permanent ligation of the left carotid artery and subsequent exposure to 2 h of hypoxia. After the HI insult, the HB-EGF mRNA was assessed by a Northern blot analysis. The levels of transcripts for HB-EGF in the cerebral cortex and the hippocampus of the ligated side were significantly higher than those of non-treated rats from 3 to 24 h after the insult. The spatial distribution of the mRNA of HB-EGF was also studied using in situ hybridization. Three to 24 h after the hypoxia, hybridization signals were intense in neuronal cytoplasm on the ligated side, but a focally decreased signal was seen in infarcted areas. Strongly increased mRNA expression was observed in the neurons surrounding the infarct. These results indicate that a neonatal HI insult induces a neuronal upregulation of HB-EGF immediately after hypoxia. In the latter model, the intracerebral NMDA injection also induced an immediate, strong upregulation of HB-EGF transcripts. Our results indicate that HB-EGF may act as a neuroprotective factor in the immature brain with HI injury by modulating the neurotoxic process which is mediated by overactivation of the NMDA receptor.

Topics: Animals; Animals, Newborn; Blotting, Northern; Brain Chemistry; Brain Ischemia; DNA Probes; Epidermal Growth Factor; Excitatory Amino Acid Agonists; Gene Expression; Heparin-binding EGF-like Growth Factor; Hypoxia; Hypoxia, Brain; In Situ Hybridization; Intercellular Signaling Peptides and Proteins; Microinjections; N-Methylaspartate; Rats; Rats, Sprague-Dawley; RNA, Messenger; Transcription, Genetic

In vitro to in vivo extrapolations require cellular models that closely mimic cells in vivo. Typically, cultured cells revert to glycolysis, have increased lactate dehydrogenase (LDH) activity, have decreased oxidative metabolism, and dedifferentiate. This study examined the role of hypoxia and proliferation in the regulation of LDH activity, and the temporal relationships among induction of glycolysis, LDH activity, and proliferation in primary cultures of rabbit renal proximal tubular cells (RPTC). LDH activity in RPTC grown under standard conditions (STILL) did not increase during the first 3 d of culture, but increased 18-fold by d 7. LDH activity in RPTC grown under conditions of increased oxygen supply (SHAKE) did not increase during the first 3 d of culture, but increased 5.5-fold by d 7. Hypoxia and proliferation were responsible for 73% and 27%, respectively, of the increase in LDH activity in STILL RPTC. Hypoxia had no effect on RPTC proliferation. Neither medium glucose nor insulin concentrations had any effect on LDH activity in SHAKE RPTC. Supplementation of the culture medium with ribose 5-phosphate or ribose diminished the increase in LDH activity in SHAKE RPTC to 62% and 52% of controls but had no effect on monolayer DNA content. Two-day treatment of confluent SHAKE RPTC with epidermal growth factor (EGF) resulted in 1.6-, 1.4-, and 1.9-fold increases in LDH and G6PDH activities and monolayer DNA content, respectively. The stimulatory effect of EGF on LDH and G6PDH activities, but not monolayer DNA content, was abolished by ribose or ribose 5-phosphate. In contrast, transforming growth factor-beta 1 (TGF-beta 1) treatment stimulated lactate production but had no effect on LDH and G6PDH activities, or proliferation of SHAKE RPTC. These results show that (1) both hypoxia and proliferation are primarily responsible for the induction of LDH activity in cultured cells, (2) LDH activity is not an accurate indicator of glycolysis, (3) induction of LDH activity is secondary and due, in part, to the induction of the pentose phosphate pathway, (4) EGF stimulates glycolysis, LDH activity, and proliferation, and (5) TGF-beta 1 stimulates glycolysis but has no effect on LDH activity or proliferation.

Topics: Analysis of Variance; Animals; Cell Division; Cells, Cultured; DNA; Dose-Response Relationship, Drug; Enzyme Induction; Epidermal Growth Factor; Female; Glycolysis; Hypoxia; Kidney Tubules, Proximal; L-Lactate Dehydrogenase; Oxygen Consumption; Rabbits; Transforming Growth Factor beta