Secretion Of Epidermal Growth Factor Research Articles

The cis-regulatory logic underlying abdominal Hox-mediated repression versus activation of regulatory elements in Drosophila

During development diverse transcription factor inputs are integrated by cis-regulatory modules (CRMs) to yield cell-specific gene expression. Defining how CRMs recruit the appropriate combinations of factors to either activate or repress gene expression remains a challenge. In this study, we compare and contrast the ability of two CRMs within the Drosophila embryo to recruit functional Hox transcription factor complexes. The DCRE CRM recruits Ultrabithorax (Ubx) and Abdominal-A (Abd-A) Hox complexes that include the Extradenticle (Exd) and Homothorax (Hth) transcription factors to repress the Distal-less leg selector gene, whereas the RhoA CRM selectively recruits Abd-A/Exd/Hth complexes to activate rhomboid and stimulate Epidermal Growth Factor secretion in sensory cell precursors. By swapping binding sites between these elements, we found that the RhoA Exd/Hth/Hox site configuration that mediates Abd-A specific activation can convey transcriptional repression by both Ubx and Abd-A when placed into the DCRE. We further show that the orientation and spacing of Hox sites relative to additional binding sites within the RhoA and DCRE is critical to mediate cell- and segment-specific output. These results indicate that the configuration of Exd, Hth, and Hox site within RhoA is neither Abd-A specific nor activation specific. Instead Hox specific output is largely dependent upon the presence of appropriately spaced and oriented binding sites for additional TF inputs. Taken together, these studies provide insight into the cis-regulatory logic used to generate cell-specific outputs via recruiting Hox transcription factor complexes.

The endocrine disruptor bisphenol A promotes nuclear ERRγ translocation, facilitating cell proliferation of Grade I endometrial cancer cells via EGF-dependent and EGF-independent pathways

Endocrine disruptors have become a global social and public health problem since the late 1980s. Bisphenol A (BPA) has a steroid-like skeleton similar to estrogen and progesterone, and is an endocrine disruptor that disturbs the physiological hormone balance. The potential involvement of BPA in malignancy of endometrial cancer cells caused by overexposure of steroid hormones remains incompletely understood. The present study aimed at understanding the regulatory mechanism underlying BPA-induced cell proliferation in hormone-sensitive endometrial cancer cells. BPA selectively and significantly induced cell proliferation of Grade I endometrial cancer cells such as HEC265 and Ishikawa cells. In HEC265 and Ishikawa cells, BPA induced nuclear translocation of estrogen-related receptor γ (ERRγ) in a time-dependent manner and increased expression of BPA/ERRγ-target genes. In Ishikawa cells, BPA promoted the influx of Ca2+ followed by epidermal growth factor (EGF) secretion to the extracellular space. Furthermore, EGF secreted from Ishikawa had an autocrine effect, leading to activation of the EGFR/ERK pathway. Contrastingly, in HEC265 cells, BPA increased the expression of BPA/ERRγ-target genes but did not affect Ca2+ mobilization EGF secretion. In conclusion, BPA induced cell proliferation via the BPA/ERRγ/EGF/EGFR/ERK signaling pathway in Ishikawa cells and contrastingly, in HEC265 cells, induced cell proliferation through the BPA/ERRγ signaling pathway.

Effects of estradiol and progesterone on secretion of epidermal growth factor and insulin-like growth factor-1 in cultured yak endometrial epithelial cells.

We isolated and purified yak (Bos grunniens) endometrial epithelial cells and assayed different concentrations of estradiol (E2) and progesterone (P4) with respect to secretion of epidermal growth factor (EGF) and insulin-like growth factor-1 (IGF-1). Uterine epithelia were confirmed with Feulgen staining, karyotype analysis, and immunohistochemistry. Then, cells were treated with E2 and P4 and cultured in serum-free medium for 24 h. EGF and IGF-1 were measured with immunofluorescence, Real-time PCR (RT-PCR), Western blot (WB), and ELISA. When E2 and P4 were applied separately, the expression of EGF and IGF-1 did not change significantly, and EGF and IGF-1 gene and protein expression and epidermal growth factor receptor (EGFR) and insulin-like growth factor receptor (IGFR) gene expression were significantly increased when both hormones were combined. When the hormones were used singly, the optimal concentration of E2 was 10 ng/mL and of P4 was 100 ng/mL. When combined, the optimal E2 concentration was 10 ng/mL and P4 was 10 ng/mL. Thus, E2 and P4 can modulate expression of EGF and IGF-1 in endometrial epithelial cells at the morphological, gene, protein, and exocrine level, which is of great significance to improve the rate of yak embryo implantation and reproduction.

Low-temperature Plasma Promotes Fibroblast Proliferation in Wound Healing by ROS-activated NF-κB Signaling Pathway.

Low-temperature plasma (LTP) has shown great promise in wound healing, although the underlying mechanism remains poorly understood. In the present study, an argon atmospheric pressure plasma jet was employed to treat L929 murine fibroblasts cultured in vitro and skin wounds in BALB/c mice. The in vitro analysis revealed that treatment of fibroblasts with LTP for 15 s resulted in a significant increase in cell proliferation, secretion of epidermal growth factor (EGF) and transforming growth factor-βi (TGF-βi), production of intracellular reactive oxygen species (ROS), and the percentage of cells in S phase, protein expression of phosphorylated p65 (P-p65) and cyclinD1, but a noted decrease in the protein expression of inhibitor kappa B (IκB). The in vitro experiments demonstrated that 30-s LTP treatment enhanced the number of fibroblasts and the ability of collagen synthesis, while 50-s treatment led to the opposite outcomes. These results suggested that LTP treatment promotes the fibroblast proliferation in wound healing by inducing the generation of ROS, upregulating the expression of P-p65, downregulating the expression of IκB, and activating the NF-κB signaling pathway and consequently altering cell cycle progression (increased DNA synthesis in S phage).

EGF stimulates glioblastoma metastasis by induction of matrix metalloproteinase-9 in an EGFR-dependent mechanism.

Epidermal growth factor (EGF) and EGF receptor (EGFR) play prominent roles in the metastasis of glioblastoma (GBM). However, the molecular mechanisms for the function of EGF and EGFR in GBM metastasis have not been elucidated. Herein, we demonstrate that coactivation of EGF and EGFR drives tumor metastasis in a matrix metalloproteinase-9 (MMP-9)–dependent manner. Expression levels of EGF, EGFR, and MMP-9 were substantially upregulated in the GBM and edema zones of patients, compared with those of paired unaffected participants. Secretion of EGF and MMP-9 was reduced in the cerebrospinal fluid (CSF) after removing GBM for 2 weeks by operation. To the mechanism, MMP-9 was upregulated by activating EGF and EGFR via PI3K/AKT- and ERK1/2-dependent pathways. Moreover, signal transducer and activator of transcription (STAT) 3 and STAT5 mediated the activation of NF-κB by PI3K/AKT and ERK1/2 pathways. This resulted in transactivation of MMP-9 in GBM. Finally, MMP-9 induction facilitated abnormal proliferation, migration, and invasion of cells, which contributed to GBM metastasis.

A Hox complex activates and potentiates the Epidermal Growth Factor signaling pathway to specify Drosophila oenocytes.

Hox transcription factors specify distinct cell types along the anterior-posterior axis of metazoans by regulating target genes that modulate signaling pathways. A well-established example is the induction of Epidermal Growth Factor (EGF) signaling by an Abdominal-A (Abd-A) Hox complex during the specification of Drosophila hepatocyte-like cells (oenocytes). Previous studies revealed that Abd-A is non-cell autonomously required to promote oenocyte fate by directly activating a gene (rhomboid) that triggers EGF secretion from sensory organ precursor (SOP) cells. Neighboring cells that receive the EGF signal initiate a largely unknown pathway to promote oenocyte fate. Here, we show that Abd-A also plays a cell autonomous role in inducing oenocyte fate by activating the expression of the Pointed-P1 (PntP1) ETS transcription factor downstream of EGF signaling. Genetic studies demonstrate that both PntP1 and PntP2 are required for oenocyte specification. Moreover, we found that PntP1 contains a conserved enhancer (PntP1OE) that is activated in oenocyte precursor cells by EGF signaling via direct regulation by the Pnt transcription factors as well as a transcription factor complex consisting of Abd-A, Extradenticle, and Homothorax. Our findings demonstrate that the same Abd-A Hox complex required for sending the EGF signal from SOP cells, enhances the competency of receiving cells to select oenocyte cell fate by up-regulating PntP1. Since PntP1 is a downstream effector of EGF signaling, these findings provide insight into how a Hox factor can both trigger and potentiate the EGF signal to promote an essential cell fate along the body plan.

MiR-200c Accelerates Hepatic Stellate Cell-Induced Liver Fibrosis via Targeting the FOG2/PI3K Pathway.

Background Although expression of miR-200s is aberrant in liver fibrosis, its role in liver fibrogenesis still remains unknown. Here, we investigated the role of miR-200c in the activation of human hepatic stellate cells (HSCs) and induction of liver fibrosis. Methods We engineered human HSCs (LX2 cell line) to stably express miR-200c (LX2-200c) or empty vector control (LX2-nc). Results miR-200c expression upregulated α-smooth muscle actin (SMA) and vimentin, enhanced HSCs growth and migration, increased expression of collagen type I (a main component of ECM) gene and secretion of epidermal growth factor (EGF), and upregulated the phosphorylation of Akt, a downstream effector of the PI3K pathway. As a target of miR-200s and inhibitor of PI3K pathway, FOG2 protein expression was significantly suppressed in LX2-200c cells. Moreover, LY294002, a highly selective inhibitor of PI3K, blocked phosphorylation of Akt and the effects of miR-200c. Conclusions These data suggest that miR-200c activates HSCs in liver fibrosis possibly by downregulating FOG2 protein expression and upregulating PI3K/Akt signaling. Autocrine activation of EGF signaling may also be a mechanism of miR-200c-mediated HSCs activation. So miR-200c can be a potential marker for HSCs activation and liver fibrosis progression, as well as a potential target to attenuate liver fibrosis.

Cytokines in saliva increase in head and neck cancer patients after treatment

Approximately one-third of advanced head and neck squamous cell carcinomas (HNSCCs) recur within 2years of treatment. Due to ease of collection, saliva is of interest to monitor changes that correlate with treatment. Previously this was a challenge due to xerostomia after conventional radiation. The emergence of gland-sparing radiation has made it possible to collect saliva post-treatment. This study investigated changes in cytokines in saliva pre- and post-treatment to provide foundational knowledge for future studies exploring the use of saliva to monitor treatment response. Pre- and post-treatment saliva was evaluated for 8 cytokines by multiplex assay and enzyme-linked immunosorbent assay. In oropharyngeal HNSCC, secretion of epidermal growth factor (EGF), GROα (Growth-regulated protein alpha), interleukin (IL)-1α, IL-β, IL-6, IL-8, tumor necrosis factor-α, and vascular endothelial growth factor increased significantly post-treatment. In additional patients, significant increases of GR-α and IL-6 were validated, but EGF showed no change. The uniqueness of this study is its comparison of salivary cytokines from HNSCC patients pre- and post-treatment.

Diminished salivary epidermal growth factor secretion: a link between Sjögren’s syndrome and autoimmune gastritis?

Objectives: Healthy human labial salivary glands produce epidermal growth factor (EGF). In Sjögren’s syndrome (SS), EGF staining is diminished. SS is also associated with chronic autoimmune corpus gastritis. We therefore hypothesized that EGF secretion would be diminished in SS and that this could affect gastric target cells.Methods: Salivary EGF secretion in SS was compared to that in healthy controls using an enzyme-linked immunosorbent assay (ELISA). EGF receptor (EGFR) immunoreactive cells in the gastric corpus of healthy human subjects were analysed using immunostaining.Results: Salivary secretion of EGF was diminished in SS patients (232.4, range 52.6–618.4, vs. 756.6, range 105.3–1631.6 pg/min, p = 0.002). Proton-pump positive parietal cells were mostly EGFR immunoreactive whereas very few pepsinogen I (PGI)-positive cells were EGFR positive.Conclusions: As EGF is relatively acid resistant, salivary gland-derived EGF might participate in an exo/endocrine mode of parietal cell maintenance in the gastric corpus. Deficiency of salivary gland-derived EGF in SS patients may cause impairment of gastric parietal cells resulting in exposure of immunogenic cryptic antigens and loss of immunological self-tolerance.

Role of Saliva in Esophageal Defense: Implications in Patients With Nonerosive Reflux Disease

BackgroundIt has been previously demonstrated that patients with reflux esophagitis exhibit a significant impairment in the secretion of salivary protective components versus controls. However, the secretion of salivary protective factors in patients with nonerosive reflux disease (NERD) is not explored. The authors therefore studied the secretion of salivary volume, pH, bicarbonate, nonbicarbonate glycoconjugate, protein, epidermal growth factor (EGF), transforming growth factor alpha (TGF-α) and prostaglandin E2 in patients with NERD and compared with the corresponding values in controls (CTRL). Methodssalivary secretion was collected during basal condition, mastication and intraesophageal mechanical (tubing, balloon) and chemical (initial saline, acid, acid/pepsin, final saline) stimulations, respectively, mimicking the natural gastroesophageal reflux. ResultsSalivary volume, protein and TGF-α outputs in patients with NERD were significantly higher than CTRL during intraesophageal mechanical (P<0.05) and chemical stimulations (P<0.05). Salivary bicarbonate was significantly higher in NERD than CTRL group during intraesophageal stimulation with both acid/pepsin (P<0.05) and saline (P<0.01). Salivary glycoconjugate secretion was significantly higher in the NERD group than the CTRL group during chewing (P<0.05), mechanical (P<0.05) and chemical stimulation (P<0.01). Salivary EGF secretion was higher in patients with NERD during mechanical stimulation (P<0.05). ConclusionsPatients with NERD demonstrated a significantly stronger salivary secretory response in terms of volume, bicarbonate, glycoconjugate, protein, EGF and TGF-α than asymptomatic controls. This enhanced salivary esophagoprotection is potentially mediating resistance to the development of endoscopic mucosal changes by gastroesophageal reflux.

Generation of Lactococcus lactis capable of coexpressing epidermal growth factor and trefoil factor to enhance in vitro wound healing.

Epidermal growth factor (EGF) and trefoil factor 3 (TFF3) are peptides that actively support the restitution and repair of mucosal epithelial barriers. Previous studies have shown that TFF3 enhanced EGF effect in wound healing, suggesting that the combined application of the two factors may be advantageous in clinical tissue repair. Expression of multiple proteins in a single host is a desirable approach in a biotechnological process, allowing to reduce cost and increase production efficiency. The aim of the present study was to study the feasibility of coexpressing EGF and TFF3 in food grade bacteria, Lactococcus lactis (L. lactis). Using an expression construct allowing simultaneous translation of two separate recombinant peptides, we generated a L. lactis that coexpressed and secreted EGF and TFF3 dually (LL-ET). Western blot analysis revealed that LL-ET secreted 45-54% more total recombinant peptides (EGF+TFF3) per flask fermentation and 21-37% more total recombinant proteins in bioreactor fermentation compared to their single factor expressing L. lactis counterparts (LL-EGF and LL-TFF3, respectively). The resulted recombinant EGF and TFF3 showed enhancement in wound healing activity in vitro. Our data suggest that the dual expression and secretion of EGF and TFF3 by L. lactis effectively accelerated cell migration, demonstrating potential future oral application of L. lactis fermentation product containing dual factors or a cocktail of factors to potentially treat intestinal damage and inflammation.

Possible involvement of tumor-producing VEGF-A in the recruitment of lymphatic endothelial progenitor cells from bone marrow.

Lymphatic metastasis of human malignant adenocarcinomas is a critical determinant of prognosis. Lymphangiogenesis, the growth of lymphatic vessels, is closely involved in lymphatic metastasis. However, the mechanisms of tumor lymphangiogenesis are not clearly understood. In a previous study, we showed that human gastric cancer MKN45 cells organize neighboring lymphatic vessels via recruitment of bone marrow-derived lymphatic endothelial progenitor cells in a nude mouse xenograft model. The present results also indicated that human colorectal cancer LS174T and breast cancer SK-BR-3 cells promoted lymphangiogenesis as well as the recruitment of lymphatic endothelial progenitor cells from bone marrow. Among growth factors, which are reported to be involved in lymphangiogenesis, only vascular endothelial growth factor (VEGF)-A was extensively secreted by these three types of adenocarcinoma cells in culture. The well-characterized lymphangiogenic factors VEGF-C and VEGF-D in the culture medium of these three types of adenocarcinoma cells were below the detectable levels in ELISA assay. Secretion of epidermal growth factor (EGF) and hepatocyte growth factor (HGF) was not detected. In in vitro culture assay, VEGF-A directly induced the differentiation of bone marrow mononuclear cells into LYVE-1-positive lymphatic endothelial lineage cells. These data collectively suggest the possibility that VEGF-A-rich human adenocarcinomas induce tumor lymphangiogenesis via recruitment of lymphangiogenic endothelial progenitor cells from bone marrow.

A distinct salivary secretory response mediated by the esophago-salivary reflex in patients with Barrett's esophagus: Its potential pathogenetic implications

PurposeA significantly compromised epidermal growth factor (EGF) secretion by basal parotid saliva may contribute to the development of Barrett's esophagus (BE). The rate of secretion of EGF as well as a wide spectrum of protective factors in total basal and stimulated saliva in BE patients remains to be explored. We therefore studied the rate of secretion of salivary buffers, glycoconjugate, protein, EGF, transforming growth factor α (TGFα) and prostaglandin E2 (PGE2), evoked by esophago-salivary reflex, in patients with BE and controls (CTRL). Material/methodsSalivary secretion was collected during basal condition, mastication, and intraesophageal mechanical and chemical stimulations respectively, mimicking the natural gastroesophageal reflux scenario. ResultsSalivary pH in BE was significantly lower than in controls during mechanical (p<0.001) and chemical stimulations (p<0.001). Bicarbonate and protein outputs in BE were significantly lower during mechanical (p<0.05) and chemical stimulations (p<0.01). The non-bicarbonate and glycoconjugate outputs in BE were lower during chemical stimulation (p<0.05) and during mechanical (p<0.05) and chemical stimulations (p<0.05) respectively. The rate of salivary EGF output in BE was significantly lower during mechanical stimulation (p<0.05). We observed a higher TGFα output during mastication (p<0.05) and PGE2 secretion during basal and masticatory condition (p<0.05) in BE. ConclusionsPatients with BE demonstrated significantly compromised salivary pH and rate of secretion of bicarbonate, non-bicarbonate, glycoconjugate, protein and EGF. This impairment could potentially predispose to the development of accelerated esophageal mucosal injury. Potential restoration of this impairment by masticatory stimulation of salivary secretion using sugarless chewing gum justifies further clinical exploration.

PI3K-mediated glioprotective effect of epidermal growth factor under oxidative stress conditions.

To determine the effects of epidermal growth factor (EGF) on the proliferation and migration of Müller cell line Moorfields/Institute of Ophthalmology-Müller 1 (MIO-M1), and its related molecular mechanisms under normal and oxidative stress conditions. Müller cells were cultured with different concentrations of EGF in the presence or absence of varied amounts of H2O2 and glucose oxidase (GO) which induced oxidative stress. The proliferation and migration of Müller cells were examined by 5-Bromo-2-deoxyUridine (BrdU), MTT assay, Transwell assay and scratch wound healing assays. The cell viability was determined with the MTT assay. The secretion of EGF by Müller cells was evaluated by ELISA. Western blot was performed to detect the activation of extracellular regulated protein kinases (ERK)1/2 and Akt signal pathways. EGF stimulated the proliferation and migration of Müller cells in a concentration-dependent manner in vitro. Under oxidative damage condition, 2h of pretreatment with 10-100 ng/mL EGF can mostly inhibit 50% lethal dose of 0.08 mmol/L H2O2-induced cell damage. The Western blot results showed that after Müller cells were exposed to varying EGF for 24h, Akt and ERK1/2 were phosphorylated in a dose-dependent manner. In the presence of the LY294002, the potent PI3K inhibitor, the p-Akt was significantly attenuated. EGF may induce the proliferation and migration of human Müller cells through the Akt and the ERK1/2 signal pathways, and induce PI3K-mediated glioprotective effect under oxidative stress.

Adipose tissue‐derived stem cells (ADSCs) transplantation promotes regeneration of expanded skin using a tissue expansion model

Transplantation of adipose tissue-derived stem cells (ADSCs) is a promising method that has been used in regenerative medicine because it has shown the capacity to accelerate wound healing. However, roles of ADSCs transplantation in expanded-skin regeneration have remained unknown. To clarify the roles, a tissue expansion model was used in this study. The study comprised three groups of 13 rats in each group: the ADSCs group, the fibroblast (FB) group, and the control group. The skin regeneration in the ADSCs group was enhanced, as evidenced by increased cell proliferation and a higher hydroxyproline content and degree of neovascularization, all with p < 0.05, when compared with both the FB group and the control group. Consistent with enhanced cell proliferation and neovascularization, the regenerated skin in the ADSCs group was much thicker, which further reduced the retraction ratio of the expanded skin. Four weeks after operation, 5'-bromo-2'-deoxyuridine-labeled ADSCs appeared in subcutaneous tissue, vascular vessels, and hair follicles. The up-regulation of protein expression, such as epidermal growth factor and vascular endothelial growth factor, primarily emerged in the ADSC group, with the up-regulated basic fibroblast growth factor appearing in the FB group. Collectively, these results suggest that the transplantation of ADSCs could enhance the regeneration of expanded skin by participating in skin structures and up-regulating the secretion of epidermal growth factor and vascular endothelial growth factor.

High and dysregulated secretion of epidermal growth factor from immune cells of patients with relapsing-remitting multiple sclerosis

We studied the secretion and regulation of epidermal growth factor (EGF) from immune cells of patients with relapsing remitting multiple sclerosis (RR-MS), and the relevance of these levels to neuronal morphology and survival. Our data suggest that the immune-mediated neuronal and oligodendroglial regeneration may be defective by the increased EGF secretion from immune cells of RR-MS patients. We also suggest an increased neurotoxicity of the immune response in RR-MS via high levels of EGF secretion. This is a heretofore unreported aspect of the immune response of patients with RR-MS. Our results may support the inadequate tissue repair that has been observed in MS.

Mechanistic Insights into Self-Reinforcing Processes Driving Abnormal Histogenesis During the Development of Pancreatic Cancer

Pancreatic ductal adenocarcinoma, one of the most feared lethal and painful diseases, is increasing in incidence. The poor prognosis of pancreatic ductal adenocarcinoma-affected patients primarily is owing to our inability to develop effective therapies. Mechanistic studies of genetic, epigenetic, and cell-to-cell signaling events are providing clues to molecular pathways that can be targeted in an attempt to cure this disease. The current review article seeks to draw inferences from available mechanistic knowledge to build a theoretical framework that can facilitate these approaches. This conceptual model considers pancreatic cancer as a tissue disease rather than an isolated epithelial cell problem, which develops and progresses in large part as a result of three positive feedback loops: i) genetic and epigenetic changes in epithelial cells modulate their interaction with mesenchymal cells to generate a dynamically changing process of abnormal histogenesis, which drives more changes; ii) the faulty tissue architecture of neoplastic lesions results in unsynchronized secretion of signaling molecules by cells, which generates an environment that is poor in oxygen and nutrients; and iii) the increased metabolic needs of rapidly dividing cells serve as an evolutionary pressure for them to adapt to this adverse microenvironment, leading to the emergence of resistant clones. We discuss how these concepts can guide mechanistic studies, as well as aid in the design of novel experimental therapeutics.

The relation among NGF, EGF and insulin is important for triggering pancreatic β cell apoptosis

Nerve growth factor (NGF) is a well-known mediator for maintaining the survival of neurons, while recent studies report that its absence induces apoptosis in cultured β cells of humans and rats. However, its relationship with other growth factors that have important roles in the survival and function of β cells such as epidermal growth factor (EGF) has not yet been elucidated. The aim of this study was to investigate the effects of NGF withdrawal on the synthesis and secretion of EGF, insulin with respect to β cell apoptosis in hyperglycemic rats. β cells were isolated from euglycemic and streptozotocin-induced hyperglycemic rats and treated with NGF neutralizing antibody for withdrawal of NGF in culture medium. NGF, EGF and insulin levels in cell lysates and secretion samples were measured by enzyme-linked immunosorbent assay, and their gene expressions were determined by real-time reverse transcription polymerase chain reaction assay. Apoptosis was quantitatively determined by cytoplasmic histone-associated DNA fragments. Nerve growth factor neutralization triggered β cell apoptosis. In addition decreased insulin, increased NGF and EGF were observed at gene expression and protein levels by NGF neutralization. Moreover, NGF withdrawal decreased secretion of these peptides from β cells. Although the alterations seemed to be similar under euglycemic and hyperglycemic conditions, NGF withdrawal more strongly affected β cells of hyperglycemic rats. These important findings indicate that NGF is an important regulator for the synthesis and secretion of EGF and insulin from the β cells. Moreover, results suggested that NGF withdrawal causes apoptosis by decreasing EGF, NGF and insulin secretion from β cells of hyperglycemic rats.

A study of the functional significance of epidermal growth factor in major depressive disorder

The precise mechanism of major depressive disorder (MDD) is poorly understood. On the basis of the neurotrophin hypothesis, initial findings from our previous studies, and the functions of epidermal growth factor (EGF) in the central nervous system, we proposed that EGF might contribute to the development of MDD, which was investigated in this study. Eight single nucleotide polymorphisms (SNPs) within the EGF gene were genotyped in 463 patients with MDD and 413 control participants among a Chinese population; of these, the plasma EGF levels of 210 patients and 223 controls were determined using the enzyme-linked immunosorbent assay. To determine the effect of functional SNPs on EGF secretion in HEK293 cells, EGF levels in the supernatants of cultured cells were also assessed. None of the informative SNPs showed an allelic association with MDD, but the cis-phase interaction between rs11569017 and rs11569126 was strongly associated with the illness (P=0.0027). The EGF levels in plasma were significantly lower in the patient group than in the control group (P<0.0001). The EGF levels were also significantly lower in patients with the rs11569017-TT genotype than those with either the AA genotype (P=0.013) or the AT genotype (P=0.004); the rs11569017 minor allele significantly affected the expression of the EGF gene (P=0.0004). The cis-phase interaction between the SNPs within the EGF locus may contribute toward the etiology of MDD. The plasma EGF levels may be a useful biomarker for the early diagnosis, treatment, and prognosis of major psychiatric disorders.

Cancer stem-like cells persist in established cell lines through autocrine activation of EGFR signaling

Recent studies have shown that a small subpopulation of stem-like cancer cells within most solid tumors are responsible for the malignancy of aggressive cancer cells, including tumorigenicity and relapse of solid tumors. These tumor cells may be enriched and maintained in vitro in the presence of growth factors (GFs), including epidermal growth factor (EGF) and basic fibroblast growth factor (bFGF), without serum in almost all solid tumor cell lines. In the present study, however, we found that the enrichment of cancer stem-like cells (CSCs) from established cell lines using sphere cultures was achieved efficiently without GFs. Enhanced sphere-forming activity was detected in GF-free cultures compared with GF-containing cultures in MCF7, A549 and U87 cells. Analysis of conditioned media (CM) demonstrated an elevated level of EGF secretion in GF-free CM compared with GF-containing CM in MCF7 cells. By contrast, cells in GF-free CM exhibited almost no secretion of bFGF, whereas cells in GF-containing CM secreted a high level of bFGF. The addition of EGF enhanced sphere formation, whereas bFGF suppressed sphere formation under GF-free conditions in MCF7 cells. Conversely, the addition of bFGF suppressed sphere formation in these cells. Notably, bFGF markedly suppressed EGF receptor (EGFR) expression and EGF secretion in MCF7 and A549 cells. Consistent with this result, EGFR blockade with pharmacological inhibitors significantly suppressed sphere formation in MCF7 and A549 cells under GF-free conditions. Furthermore, the neutralization of EGF also inhibited sphere formation, whereas bFGF neutralization still enhanced sphere formation under these conditions. Together, CSCs may be maintained in a serum-free culture condition without GFs, possibly through autocrine secretion of GFs such as EGF, and the addition of bFGF may not be sufficient for the enrichment of stem-like cancer cells.