Heparin-binding (HB)-EGF, a ligand for EGF receptors, is synthesized as a membrane-anchored precursor that is potentially capable of juxtacrine activation of EGF receptors. However, the physiological importance of such juxtacrine signaling remains poorly described, due to frequent inability to distinguish effects mediated by membrane-anchored HB-EGF vs. mature "secreted HB-EGF." In our studies, using stable expression of a noncleavable, membrane-anchored rat HB-EGF isoform (MDCK(rat5aa) cells) in Madin-Darby canine kidney (MDCK) II cells, we observed a significant increase in transepithelial resistance (TER). Similar significant increases in TER were observed on stable expression of an analogous, noncleavable, membrane-anchored human HB-EGF construct (MDCK(human5aa) cells). The presence of noncleavable, membrane-anchored HB-EGF led to alterations in the expression of selected claudin family members, including a marked decrease in claudin-2 in MDCK(rat5aa) cells compared with the control MDCK cells. Reexpression of claudin-2 in MDCK(rat5aa) cells largely prevented the increases in TER. Ion substitution studies indicated decreased paracellular ionic permeability of Na(+) in MDCK(rat5aa) cells, further indicating that the altered claudin-2 expression mediated the increased TER seen in these cells. In a Ca(2+)-switch model, increased phosphorylation of EGF receptor and Akt was observed in MDCK(rat5aa) cells compared with the control MDCK cells, and inhibition of these pathways inhibited TER changes specifically in MDCK(rat5aa) cells. Therefore, we hypothesize that juxtacrine activation of EGFR by membrane-anchored HB-EGF may play an important role in the regulation of tight junction proteins and TER.

Secretion of surfactant proteins A and D (SP-A and SP-D) has been difficult to study in vitro because a culture system for maintaining surfactant secretion has been difficult to establish. We evaluated several growth factors, corticosteroids, rat serum, and a fibroblast feeder layer for the ability to produce and maintain a polarized epithelium of type II cells that secretes SP-A and SP-D into the apical medium. Type II cells were plated on a filter insert coated with an extracellular matrix and were cultured at an air-liquid interface. Keratinocyte growth factor (KGF) stimulated type II cell proliferation and secretion of SP-A and SP-D more than fibroblast growth factor-10 (FGF-10), hepatocyte growth factor (HGF), or heparin-binding epidermal-like growth factor (HB-EGF). Cells cultured in the presence of KGF and rat serum with or without fibroblasts had high surfactant protein mRNA levels and exhibited a high level of SP-A and SP-D secretion. Dexamethasone inhibited type II cell proliferation but increased expression of SP-B. In the presence of KGF, rat serum, and dexamethasone, the mRNAs for the surfactant proteins were maintained at high levels. Secretion of SP-A and SP-D was found to be independent of phospholipid secretion.

To gain insight into the transformation of epidermal cells into squamous carcinoma cells (SCC), we compared the response to ultraviolet B radiation (UVB) of normal human epidermal keratinocytes (NHEK) versus their transformed counterpart, SCC, using biological and molecular profiling. DNA microarray analyses (Affymetrix), approximately 12000 genes) indicated that the major group of upregulated genes in keratinocytes fall into three categories: (i). antiapoptotic and cell survival factors, including chemokines of the CXC/CC subfamilies (e.g. IL-8, GRO-1, -2, -3, SCYA20), growth factors (e.g. HB-EGF, CTGF, INSL-4), and proinflammatory mediators (e.g. COX-2, S100A9), (ii). DNA repair-related genes (e.g. GADD45, ERCC, BTG-1, Histones), and (iii). ECM proteases (MMP-1, -10). The major downregulated genes are DeltaNp63 and PUMILIO, two potential markers for the maintenance of keratinocyte stem cells. NHEK were found to be more resistant than SCC to UVB-induced apoptosis and this resistance was mainly because of the protection from cell death by secreted survival factors, since it can be transferred from NHEK to SCC cultures by the conditioned medium. Whereas the response of keratinocytes to UVB involved regulation of key checkpoint genes (p53, MDM2, p21(Cip1), DeltaNp63), as well as antiapoptotic and DNA repair-related genes - no or little regulation of these genes was observed in SCC. The effect of UVB on NHEK and SCC resulted in upregulation of 251 and 127 genes, respectively, and downregulation of 322 genes in NHEK and 117 genes in SCC. To further analyse these changes, we used a novel unsupervised coupled two-way clustering method that allowed the identification of groups of genes that clearly partitioned keratinocytes from SCC, including a group of genes whose constitutive expression levels were similar before UVB. This allowed the identification of discriminating genes not otherwise revealed by simple static comparison in the absence of UVB irradiation. The implication of the changes in gene profile in keratinocytes for epithelial cancer is discussed.

OBJECTIVE

To determine the role of epidermal growth factor (EGF) receptor (EGFR)-mediated signaling pathways in preventing infection-induced apoptosis in human corneal epithelial cells (HCECs).

METHODS

Epithelial monolayers of a telomerase-immortalized HCEC line, HUCL, and primary culture of HCECs were infected with Pseudomonas aeruginosa in the presence of the EGFR inhibitor tyrphostin AG1478, the extracellular signal-regulated kinase (ERK) inhibitor U0126, the phosphoinositide 3-kinase (PI3K) inhibitor LY294002, the heparin-binding EGF-like growth factor (HB-EGF) antagonist CRM197, the HB-EGF neutralizing antibody, or the matrix metalloproteinase inhibitor GM6001. The activation of EGFR was analyzed by immunoprecipitation using EGFR antibodies, followed by Western blot analysis with phosphotyrosine antibody. Phosphorylation of ERK and Akt, a major substrate of PI3K, and generation of cleaved caspase-3 and poly (ADP-ribose) polymerase (PARP) were determined by Western blot analysis. Apoptotic cells were characterized by positive staining of active caspase-3, loss of mitochondrial cytochrome c, and condensation of chromosomes. Apoptosis was also confirmed by measuring caspase-3 activity and assessing the generation of cleaved caspase-3 and PARP.

RESULTS

P. aeruginosa infection of HUCL cells resulted in EGFR activation and EGFR-dependent ERK1/2 and PI3K phosphorylation. Inhibition of EGFR, ERK1/2, and PI3K activities with kinase-specific inhibitors (AG1478, U0126, and LY294002, respectively) resulted in an increase in the number of apoptotic cells, in elevated cellular caspase-3 activity, and/or in increased cleaved PARP in P. aeruginosa-infected HUCL cells or primary culture of HCECs. Blocking HB-EGF ectodomain shedding by inhibition of matrix metalloproteinase-mediated proteolysis, downregulation of HB-EGF, or neutralization of its activity retarded infection-induced EGFR transactivation and, as a consequence, increased infection-induced HUCL apoptosis.

CONCLUSIONS

Bacterial infection of HCECs induces EGFR transactivation through HB-EGF ectodomain shedding. EGFR and its downstream ERK and PI3K signaling pathways play a role in preventing epithelial apoptosis in the early stage of bacterial infection.

Ovarian cancer (OvCa) is the fifth most common cause of death from all cancers among women in United Sates and the leading cause of death from gynecological malignancies. While most OvCa patients initially respond to surgical debulking and chemotherapy, 75% of patients later succumb to the disease. Thus, there is an urgent need to test novel therapeutic agents to counteract the high mortality rate associated with OvCa. In this context, we have developed and engineered Nanoceria (NCe), nanoparticles of cerium oxide, possessing anti-oxidant properties, to be used as a therapeutic agent in OvCa. We show for the first time that NCe significantly inhibited production of reactive oxygen species (ROS) in A2780 cells, attenuated growth factor (SDF1, HB-EGF, VEGF(165) and HGF) mediated cell migration and invasion of SKOV3 cells, without affecting the cell proliferation. NCe treatment also inhibited VEGF(165) induced proliferation, capillary tube formation, activation of VEGFR2 and MMP2 in human umbilical vascular endothelial cells (HUVEC). NCe (0.1 mg/kg body weigh) treatment of A2780 ovarian cancer cells injected intra-peritoneally in nude mice showed significant reduction (p<0.002) in tumor growth accompanied by decreased tumor cell proliferation as evident from reduced tumor size and Ki67 staining. Accumulation of NCe was found in tumors isolated from treated group using transmission electron microscopy (TEM) and inductively coupled plasma mass spectroscopy (ICP-MS). Reduction of the tumor mass was accompanied by attenuation of angiogenesis, as observed by reduced CD31 staining and specific apoptosis of vascular endothelial cells. Collectively, these results indicate that cerium oxide based NCe is a novel nanoparticle that can potentially be used as an anti-angiogenic therapeutic agent in ovarian cancer.

OBJECTIVE

Pasteurized, donated milk is increasingly provided to preterm infants in the absence of mother's own milk. The aim of this study was to determine the effect of pasteurization on the concentration of selected components in donated human breast milk.

METHODS

Donated milk from 34 mothers was pooled into 17 distinct batches (4 mothers per batch). Aliquots of each batch were then Holder pasteurized (62.5 °C for 30 min). Interferon-γ (IFN-γ), tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), IL-2, IL-4, IL-5, IL-8, IL-10, IL-12p70 and IL-13 were measured in a multiplex enzyme-linked immunosorbent assay (ELISA). Granulocyte colony-stimulating factor (G-CSF), heparin-binding epidermal-like growth factor (HB-EGF) and hepatocyte growth factor (HGF) were measured by ELISA. Lipids were assessed by gas chromatography and gangliosides by the resorcinol-HCl reaction.

RESULTS

IFN-γ, TNF-α, IL-1β, IL-10 and HGF were significantly reduced by pasteurization (P<0.05). Gangliosides were not affected, but the proportion of medium-chain saturated fats was increased (P<0.05) with a trend towards a decreased proportion of oleic acid (P=0.057).

CONCLUSIONS

Pasteurization significantly reduced the concentration of several immunoactive compounds present in breast milk, but did not have an impact on others.

Glioblastoma multiforms (GBMs) are highly vascularized brain tumors containing a subpopulation of multipotent cancer stem cells. These cells closely interact with endothelial cells in neurovascular niches. In this study, we have uncovered a close link between the Notch1 pathway and the tumoral vascularization process of GBM stem cells. We observed that although the Notch1 receptor was activated, the typical target proteins (HES5, HEY1, and HEY2) were not or barely expressed in two explored GBM stem cell cultures. Notch1 signaling activation by expression of the intracellular form (NICD) in these cells was found to reduce their growth rate and migration, which was accompanied by the sharp reduction in neural stem cell transcription factor expression (ASCL1, OLIG2, and SOX2), while HEY1/2, KLF9, and SNAI2 transcription factors were upregulated. Expression of OLIG2 and growth were restored after termination of Notch1 stimulation. Remarkably, NICD expression induced the expression of pericyte cell markers (NG2, PDGFRβ, and α-smooth muscle actin [αSMA]) in GBM stem cells. This was paralleled with the induction of several angiogenesis-related factors most notably cytokines (heparin binding epidermal growth factor [HB-EGF], IL8, and PLGF), matrix metalloproteinases (MMP9), and adhesion proteins (vascular cell adhesion molecule 1 [VCAM1], intercellular adhesion molecule 1 [ICAM1], and integrin alpha 9 [ITGA9]). In xenotransplantation experiments, contrasting with the infiltrative and poorly vascularized tumors obtained with control GBM stem cells, Notch1 stimulation resulted in poorly disseminating but highly vascularized grafts containing large vessels with lumen. Notch1-stimulated GBM cells expressed pericyte cell markers and closely associated with endothelial cells. These results reveal an important role for the Notch1 pathway in regulating GBM stem cell plasticity and angiogenic properties.

Maternal milk is a complex fluid, with multifunctional roles within the developing gastrointestinal tract. Epidermal growth factor (EGF) and heparin-binding EGF-like growth factor (HB-EGF) are members of the family of EGF-related peptides. Biological actions of these growth factors are mediated via interaction with the EGF-receptor (EGF-R). In the early postnatal period, breast milk is the major source of EGF for the developing intestinal mucosa. HB-EGF is also detected in breast milk, but in concentrations 2 to 3 times lower than EGF. With normal physiological conditions, the intestinal epithelium undergoes a continuing process of cell proliferation, differentiation, and maturation. EGF plays an important role in these processes. In pathophysiologic situations, EGF contributes to epithelial protection from injury and post-injury mucosal repair. Necrotizing enterocolitis (NEC) is a devastating disease affecting infants born prematurely. The pathogenesis of NEC is not known, and there is no effective treatment for this disease. In an experimental NEC model, oral administration of a physiological dose of EGF significantly reduces the incidence and severity of NEC. HB-EGF provides similar protection against NEC, but only when pharmacological doses are used. Further studies are necessary before EGF can be introduced as an efficient therapeutic approach of intestinal injury.

The abnormal expression of several microRNAs has a causal role in tumorigenesis with either antineoplastic or oncogenic functions. Here we demonstrated that miR-126 and miR-126* play a tumor suppressor role in human melanoma through the direct or indirect repression of several key oncogenic molecules. The expression levels of miR-126&126* were elevated in normal melanocytes and primary melanoma cell lines, whereas they markedly declined in metastatic cells. Indeed, the restored expression of miR-126&126* in two advanced melanoma cell lines was accompanied by a significant reduction of proliferation, invasion and chemotaxis in vitro as well as of growth and dissemination in vivo. In accordance, the reverse functional effects were obtained by knocking down miR-126&126* by transfecting antisense LNA oligonucleotides in melanoma cells. Looking for the effectors of these antineoplastic functions, we identified ADAM9 and MMP7, two metalloproteases playing a pivotal role in melanoma progression, as direct targets of miR-126&126*. In addition, as ADAM9 and MMP7 share a role in the proteolytic cleavage of the HB-EGF precursor, we looked for the effectiveness of this regulatory pathway in melanoma, confirming the decrease of HB-EGF activation as a consequence of miR-126&126*-dependent downmodulation of ADAM9 and MMP7. Finally, gene profile analyses showed that miR-126&126* reexpression was sufficient to inactivate other key signaling pathways involved in the oncogenic transformation, as PI3K/AKT and MAPK, and to restore melanogenesis, as indicated by KIT/MITF/TYR induction. In view of this miR-126&126* wide-ranging action, we believe that the replacement of these microRNAs might be considered a promising therapeutic approach.

Cancer cells cultured in physiologically relevant, three-dimensional (3D) matrices can recapture many essential features of native tumor tissues. In this study, a hyaluronic acid (HA)-based bilayer hydrogel system that not only supports the tumoroid formation from LNCaP prostate cancer (PCa) cells, but also simulates their reciprocal interactions with the tumor-associated stroma was developed and characterized. HA hydrogels were prepared by mixing solutions of HA precursors functionalized with acrylate groups (HA-AC) and reactive thiols (HA-SH) under physiological conditions. The resultant viscoelastic gels have an average elastic modulus of 234 ± 30 Pa and can be degraded readily by hyaluronidase. The orthogonal and cytocompatible nature of the crosslinking chemistry permits facile incorporation of cytokine-releasing particles and PCa cells. In our bilayer hydrogel construct, the top layer contains heparin (HP)-decorated, HA-based hydrogel particles (HGPs) capable of releasing heparin-binding epidermal growth factor-like growth factor (HB-EGF) in a sustained manner at a rate of 2.5 wt%/day cumulatively. LNCaP cells embedded in the bottom layer receive the growth factor signals from the top, and in response form enlarging tumoroids with an average diameter of 85 μm by day 7. Cells in 3D hydrogels assemble into spherical tumoroids, form close cellular contacts through E-cadherin, and show cortical organization of F-actin, whereas those plated as 2D monolayers adopt a spread-out morphology. Compared to cells cultured on 2D, the engineered tumoroids significantly increased the expression of two pro-angiogenic factors, vascular endothelial growth factor-165 (VEGF(165)) and interleukin-8 (IL-8), both at mRNA and protein levels. Overall, the HA model system provides a useful platform for the study of tumor cell responses to growth factors and for screening of anticancer drugs targeting these pathways.

We recently have shown that activated Ras, but not Raf, causes transformation of intestinal (RIE-1, IEC-6) epithelial cells, whereas both activated Ras and Raf transform NIH 3T3 fibroblasts (Oldham, S. M., Clark, G. J., Gangarosa, L. M., Coffey, R. J., and Der, C. J. (1996) Proc. Natl. Acad. Sci. U. S. A. 93, 6924-6928). The observations that conditioned medium from Ras-, but not Raf-, transfected RIE-1 cells, as well as exogenous transforming growth factor alpha (TGFalpha), promoted morphological transformation of parental RIE-1 cells prompted us to identify epidermal growth factor (EGF) receptor (EGFR) ligands produced by Ras-transformed RIE-1 cells responsible for this autocrine effect. Since studies in fibroblasts have shown that v-Src is transforming, we also determined if v-Src could transform RIE-1 cells. H- or K-Ras-transformed cells secreted significant amounts of TGFalpha protein, and mRNA transcripts for TGFalpha, amphiregulin (AR), and heparin-binding EGF-like growth factor (HB-EGF) were induced. Like Ras, v-Src caused morphological and growth transformation of parental RIE-1 cells. However, TGFalpha protein was not secreted by RIE-1 cells stably expressing v-Src or activated Raf, and only minor increases in EGFR ligand mRNA expression were detected in these cells. A selective EGFR tyrosine kinase inhibitor PD153035 attenuated the Ras-, but not Src-, transformed phenotype. Taken together, these observations provide a mechanistic and biochemical basis for the ability of activated Ras, but not activated Raf, to cause transformation of RIE-1 cells. Finally, we suggest that an EGFR-dependent mechanism is necessary for Ras, but not Src, transformation of these intestinal epithelial cells.

The vasculature consists of endothelial cells (ECs) lined by pericyte/vascular smooth muscle cells (vSMCs). Pericyte/vSMCs provide support to the mature vasculature but are also essential for normal blood vessel development. To determine how pericyte-EC communication influences vascular development, we used the well-established in vitro model of TGFbeta-stimulated differentiation of 10T1/2 cells into pericyte/vSMCs. Microarray analysis was performed to identify genes that were differentially expressed by induced vs. uninduced 10T1/2 cells. We discovered that these cells show an angiogenic program of gene expression, with up-regulation of several genes previously implicated in angiogenesis, including VEGF, IL-6, VEGF-C, HB-EGF, CTGF, tenascin C, integrin alpha5, and Eph receptor A2. Up-regulation of some genes was validated by Western blots and immunocytochemistry. We also examined the functional significance of these gene expression changes. VEGF and IL-6 alone and in combination were important in 10T1/2 cell differentiation. Furthermore, we used a coculture system of 10T1/2 and human umbilical vein ECs (HUVECs), resulting in the formation of cordlike structures by the HUVECs. This cordlike structure formation was disrupted when neutralizing antibodies to VEGF or IL-6 were added to the coculture system. The results of these studies show that factors produced by pericytes may be responsible for recruiting ECs and promoting angiogenesis. Therefore, a further understanding of the genes involved in pericyte differentiation could provide a novel approach for developing anti-angiogenic therapies.

We previously reported that schwannoma-derived growth factor (SDGF), a member of heparin-binding epidermal growth factor (EGF) family, participates in autocrine pathways and promotes rat glioma cell growth. To investigate the potential role of similar molecules in human gliomas, we examined 7 human glioma cell lines and 11 glioblastoma specimens for expression of the human homologue of SDGF, amphiregulin (AR), as well as heparin-binding EGF-like growth factor (HB-EGF). Northern blot analysis revealed that only one cell line and no tumor specimens expressed AR mRNA. In contrast, HB-EGF mRNA was expressed in all human glioma cell lines and its level of expression was two- to five-fold higher than that of control brain tissues in 8 of 11 glioblastoma cases. Immunohistochemistry demonstrated that membrane-anchored HB-EGF (proHB-EGF) and EGFR were co-expressed in 44% of 34 human malignant gliomas. Introduction of exogenous HB-EGF (10 ng/ml) increased human glioma cell proliferation, and anti-HB-EGF blocking antibodies reduced the growth of glioma cells by 30-40%, confirming the presence of an autocrine loop. When added to the medium, transforming growth factor-alpha, basic fibroblast growth factor, or HB-EGF rapidly induced HB-EGF mRNA expression. These results indicate that HB-EGF and proHB-EGF contribute to the growth of human malignant glioma cells, most likely through autocrine and juxtacrine mechanisms.

Fluids that accumulate at wound sites may be an important reservoir of growth factors that promote the normal wound healing response. The presence of heparin-binding growth factors was studied in burn wound fluid (BWF) from 45 pediatric patients who had sustained partial thickness burns. One of the growth factors present was similar to platelet-derived growth factor (PDGF) based on its heparin affinity, inhibition of bioactivity by a PDGF antiserum, and detection in a PDGF-AB enzyme-linked immunosorbent assay. A second growth factor was identified as heparin-binding epidermal growth factor-like growth factor (HB-EGF) based on its heparin affinity, competition with 125I-labeled epidermal growth factor (EGF) for EGF receptor binding, and recognition in biological assays and Western blots by two HB-EGF antisera. Amino acid sequence analysis of one form of this second growth factor verified its identity as an N-terminally truncated form of HB-EGF. Immunohistochemical analysis of partial thickness burns demonstrated the presence of HB-EGF in the advancing epithelial margin, islands of regenerating epithelium within the burn wound, and in the duct and proximal tubules of eccrine sweat glands. HB-EGF in the surface epithelium of burn wounds was uniformally distributed, whereas it was restricted to the basal epithelium in nonburned skin. These data support a role for PDGF and HB-EGF in burn wound healing and suggest that the response to injury includes deposition of HB-EGF and PDGF into blister fluid and a redistribution of HB-EGF in the surface epithelium near the wound site.

OBJECTIVE

This study examined whether heparin-binding epidermal growth factor (EGF) like growth factor (HB-EGF), a proven intestinal cytoprotective molecule, exerts its protective effects through modulation of adhesion molecule expression and inflammatory cell infiltration, important pathogenic mediators of ischemia/reperfusion (I/R) injury.

METHODS

Total midgut I/R injury in rats was achieved by occlusion of the superior mesenteric artery for 90 minutes followed by reperfusion. Rats were treated intraluminally with 600 microg/kg HB-EGF or with PBS 45 minutes after the onset of ischemia. Four- or 24-hours post-I/R, ileum was harvested and processed for immunhistochemical detection of P-/E-selectins, intercellular adhesion molecule-1 (ICAM-1)/vascular cell adhesion molecule-1 (VCAM-1), and polymorphonuclear cells (PMN)/macrophages (MPhi).

RESULTS

P-/E-selectins were significantly induced in vascular endothelia 4 hours after I/R injury compared with normal intestine. HB-EGF treatment significantly down-regulated the expression of P-/E-selectins. I/R-injured intestine displayed overexpression of ICAM-1 and VCAM-1, which were significantly down-regulated by HB-EGF treatment. Lastly, I/R injury caused significant infiltration of PMN and MPhi into wounded tissue 24 hours after I/R compared with normal intestine. HB-EGF treatment significantly decreased PMN and MPhi infiltration into the injured tissue.

CONCLUSIONS

HB-EGF intestinal cytoprotection is mediated, in part, by down-regulation of expression of adhesion molecules and infiltration of PMN and MPhi after intestinal I/R injury.

Neuroendocrine (NE) differentiation in prostate cancer (PCa) has been found in some studies to correlate with unfavorable clinical outcome. The mechanisms by which PCa acquires NE properties are poorly understood. In this study, we demonstrate that heparin-binding epidermal growth factor-like growth factor (HB-EGF), a prostate smooth muscle-derived mitogen and survival factor, can evoke NE differentiation in LNCaP human PCa cells. HB-EGF induction of NE differentiation was mediated by a mitogen-activated protein kinase (MAPK) kinase-dependent mechanism, and this process was blocked by p38 MAPK signaling. NE differentiation induced by HB-EGF occurred independently of STAT3 phosphorylation and coincided with continued cell cycle transit. These findings suggest that endogenous stroma-derived factors, acting through MAPK signaling pathways, may play a significant role in the acquisition of NE properties by PCa cells. They also demonstrate that withdrawal from the cell cycle is not a prerequisite for expression of NE characteristics by PCa.

Clones were obtained that encode the rat and mouse forms of heparin-binding EGF-like growth factor (HB-EGF), a potent mitogen for smooth muscle cells, fibroblasts and keratinocytes that is proposed to be derived from a transmembrane precursor. Within the HB-EGF precursor sequences predicted from these cDNAs, the region corresponding to the secreted ("mature") factor was found to represent one of the least well conserved areas when compared to human or monkey HB-EGF (73-76% sequence identity). Regions of high sequence conservation included the proposed juxtamembrane and transmembrane domains, as well as a proposed heparin-binding region within the "mature" factor. Northern blotting experiments using the HB-EGF clones as probes revealed HB-EGF transcript expression in multiple tissues, particularly lung, skeletal muscle, brain, and heart.

BACKGROUND

Pre-eclampsia is a disorder of pregnancy associated with poor extravillous cytotrophoblast invasion and above-normal rates of apoptosis in the trophoblast. Heparin-binding epidermal-growth-factor-like growth factor (HB-EGF) has strong cytoprotective activity and is an important signalling protein that regulates trophoblast invasion during early placentation. We aimed to establish whether HB-EGF expression is altered in placentae of pre-eclamptic women.

METHODS

We assessed the expression of HB-EGF mRNA and protein by in-situ hybridisation and immunohistochemical techniques, respectively, in archived placental tissues from pregnancies terminated at around 20 weeks of gestation, and from women delivering between weeks 19 and 35 of gestation with preterm labour, small for gestational age infants, or pre-eclampsia.

RESULTS

HB-EGF mRNA and protein were expressed in villous and extravillous cytotrophoblast cells up to week 35 of gestation in placentae from women who delivered preterm. Similar levels of HB-EGF protein were found in the placentae of women who were not in labour. HB-EGF expression was reduced about five-fold (p=0.0001) in pre-eclamptic pregnancies. Fetal growth retardation, which has been linked with shallow trophoblast invasion and moderate apoptosis, was associated with placentae expressing intermediate levels of HB-EGF.

CONCLUSIONS

In pre-eclampsia, deficient HB-EGF signalling during placental development could impair trophoblast survival, differentiation, and invasion, leading to poor placental perfusion and hypertension.

OBJECTIVE

To characterize the angiogenic and inflammatory vitreous biomarker profiles in a spectrum of ischemic retinopathies, including neovascular glaucoma.

METHODS

This institutional review board-approved study retrospectively analyzed 80 undiluted vitreous samples obtained during pars vitrectomy. The specimens were frozen (-80°C) and sent for concentration analysis of 34 proteins by Bio-Plex Pro assays. Specimens were divided into four groups: patients undergoing epiretinal membrane (ERM) peeling and/or macular hole (MH) surgery with no history of diabetes (non-DM group), patients undergoing ERM peeling, and/or MH surgery with a history of diabetes (DM group), patients with proliferative diabetic retinopathy (PDR group), and patients with neovascular glaucoma (NVG group). Parametric and nonparametric analyses of demographics and cytokine levels were performed using SPSS.

RESULTS

There were no significant differences in demographics among cohorts. Numerous proteins were significantly elevated between non-DM and DM (G-CSF, sCD40L, Endoglin, IL-6, placental growth factor [PlGF], VEGF-D), DM and PDR (leptin, IL-8, PlGF, VEGF-A), and PDR and NVG (G-CSF, leptin, TIE-2, sCD40L, EGF, HB-EGF, IL-6, IL-8, PlGF, TNF-α). Only PlGF was significantly elevated between each successive cohort. The most potent drivers of NVG were PlGF, VEGF-A, IL-6, and IL-8.

CONCLUSIONS

While the role of angioproliferative growth factors is well documented in ischemic retinopathy, our study delineates the importance of inflammatory and previously underreported angiogenic proteins. It also demonstrates a significant incremental increase in certain factors with increasing levels of ischemia. Both of these findings may guide the development of future therapies for ischemic retinopathies.

Marek's disease virus (MDV) is a highly pathogenic and oncogenic herpesvirus of chickens. MDV encodes a basic leucine zipper (bZIP) protein, Meq (MDV EcoQ). The bZIP domain of Meq shares homology with Jun/Fos, whereas the transactivation/repressor domain is entirely different. Increasing evidence suggests that Meq is the oncoprotein of MDV. Direct evidence that Meq transforms chicken cells and the underlying mechanism, however, remain completely unknown. Taking advantage of the DF-1 chicken embryo fibroblast transformation system, a well established model for studying avian sarcoma and leukemia oncogenes, we probed the transformation properties and pathways of Meq. We found that Meq transforms DF-1, with a cell morphology akin to v-Jun and v-Ski transformed cells, and protects DF-1 from apoptosis, and the transformed cells are tumorigenic in chorioallantoic membrane assay. Significantly, using microarray and RT-PCR analyses, we have identified up-regulated genes such as JTAP-1, JAC, and HB-EGF, which belong to the v-Jun transforming pathway. In addition, c-Jun was found to form stable dimers with Meq and colocalize with it in the transformed cells. RNA interference to Meq and c-Jun down-modulated the expression of these genes and reduced the growth of the transformed DF-1, suggesting that Meq transforms chicken cells by pirating the Jun pathway. These data suggest that avian herpesvirus and retrovirus oncogenes use a similar strategy in transformation and oncogenesis.

Despite significant infiltration into tumors and atherosclerotic plaques, the role of T lymphocytes in these pathological conditions is still unclear. We have demonstrated that tumor-infiltrating lymphocytes (TILs) and plaque-infiltrating lymphocytes (PILs) produce heparin-binding epidermal growth factor-like growth factor (HB-EGF) and basic fibroblast growth factor (bFGF) in vitro under nonspecific conditions and in vivo in tumors by immunohistochemical staining. HB-EGF and bFGF derived from TILs and PILs directly stimulated tumor cells and vascular smooth muscle cells (SMCs) in vitro, respectively, while bFGF displayed angiogenic properties. Therefore, T cells may play a critical role in the SMC hyperplasia of atherosclerosis and support tumor progression by direct stimulation and angiogenesis.

17β-Estradiol (estrogen), through receptor binding and activation, is required for mammary gland development. Estrogen stimulates epithelial proliferation in the mammary gland, promoting ductal elongation and morphogenesis. In addition to a developmental role, estrogen promotes proliferation in tumorigenic settings, particularly breast cancer. The proliferative effects of estrogen in the normal breast and breast tumors are attributed to estrogen receptor α. Although in vitro studies have demonstrated that the G protein-coupled estrogen receptor (GPER, previously called GPR30) can modulate proliferation in breast cancer cells both positively and negatively depending on cellular context, its role in proliferation in the intact normal or malignant breast remains unclear. Estrogen-induced GPER-dependent proliferation was assessed in the immortalized nontumorigenic human breast epithelial cell line, MCF10A, and an ex vivo organ culture model employing human breast tissue from reduction mammoplasty or tumor resections. Stimulation by estrogen and the GPER-selective agonist G-1 increased the mitotic index in MCF10A cells and proportion of cells in the cell cycle in human breast and breast cancer explants, suggesting increased proliferation. Inhibition of candidate signaling pathways that may link GPER activation to proliferation revealed a dependence on Src, epidermal growth factor receptor transactivation by heparin-bound EGF and subsequent ERK phosphorylation. Proliferation was not dependent on matrix metalloproteinase cleavage of membrane-bound pro-HB-EGF. The contribution of GPER to estrogen-induced proliferation in MCF10A cells and breast tissue was confirmed by the ability of GPER-selective antagonist G36 to abrogate estrogen- and G-1-induced proliferation, and the ability of siRNA knockdown of GPER to reduce estrogen- and G-1-induced proliferation in MCF10A cells. This is the first study to demonstrate GPER-dependent proliferation in primary normal and malignant human tissue, revealing a role for GPER in estrogen-induced breast physiology and pathology.

Regeneration of the urothelium is rapid and effective in order to maintain a barrier to urine following tissue injury. Whereas normal human urothelial (NHU) cells are mitotically quiescent and G0 arrested in situ, they rapidly enter the cell cycle upon seeding in primary culture and show reversible growth arrest at confluency. We have used this as a model to investigate the role of EGF receptor signaling in urothelial regeneration and wound-healing. Transcripts for HER-1, HER-2, and HER-3 were expressed by quiescent human urothelium in situ. Expression of HER-1 was upregulated in proliferating cultures, whereas HER-2 and HER-3 were more associated with a growth-arrested phenotype. NHU cells could be propagated in the absence of exogenous EGF, but autocrine signaling through HER-1 via the MAPK and PI3-kinase pathways was essential for proliferation and migration during urothelial wound repair. HB-EGF was expressed by urothelium in situ and HB-EGF, epiregulin, TGF-alpha, and amphiregulin were expressed by proliferating NHU cells. Urothelial wound repair in vitro was attenuated by neutralizing antibodies against HER-1 ligands, particularly amphiregulin. By contrast, the same ligands applied exogenously promoted migration, but inhibited proliferation, implying that HER-1 ligands provoke differential effects in NHU cells depending upon whether they are presented as soluble or juxtacrine ligands. We conclude that proliferation and migration during wound healing in NHU cells are mediated through an EGFR autocrine signalling loop and our results implicate amphiregulin as a key mediator.

Growth factor signaling can affect tissue remodeling through autocrine/paracrine mechanisms. Recent evidence indicates that EGF receptor transactivation by heparin-binding EGF (HB-EGF) contributes to hypertrophic signaling in cardiomyocytes. Here, we show that HB-EGF operates in a spatially restricted circuit in the extracellular space within the myocardium, revealing the critical nature of the local microenvironment in intercellular signaling. This highly localized microenvironment of HB-EGF signaling was demonstrated with 3D morphology, consistent with predictions from a computational model of EGF signaling. HB-EGF secretion by a given cardiomyocyte in mouse left ventricles led to cellular hypertrophy and reduced expression of connexin43 in the overexpressing cell and in immediately adjacent cells but not in cells farther away. Thus, HB-EGF acts as an autocrine and local paracrine cardiac growth factor that leads to loss of gap junction proteins within a spatially confined microenvironment. These findings demonstrate how cells can coordinate remodeling with their immediate neighboring cells with highly localized extracellular EGF signaling.