Exogenous Epidermal Growth Factor Research Articles

Comparison of the effects of EGF, FGF-b, and NGF on the proliferation, migration, and reprogramming of primary rat Müller cells.

During the healing process of full-thickness macular holes (FTMHs), the closure and recovery of the hole depend on the migration, proliferation, and activation of Müller cells to promote the closure of holes and restoration of the photosensitive layer. In this study, we investigated the ability of the epidermal growth factor (EGF), fibroblast growth factor-basic (FGF-b), and nerve growth factor (NGF) to influence this process by regulating proliferation, migration, and reprogramming of primary rat Müller cells. Cell proliferation was measured using CCK8 [2- (2-Methoxy-4-nitrophenyl)-3- (4-nitrophenyl)-5- (2,4-disulfophenyl)-2H-tetrazolium Sodium Salt] colorimetric assays and EdU [5-Ethynyl-2'-deoxyuridine] assays over 48 h. Cell migration was measured using scratch-wound assays and transwell migration assays over 48 h. In addition, we conducted Western blot assays and immunofluorescence assays on cells that were specially treated for 1, 3, and 5 days for cell reprogramming. The percentage of EdU-positive cells in Nestin-positive have also been tested by co-immunofluorescence (Co-IF) staining. EGF and FGF-b significantly promoted the proliferation of Müller cells (p < 0.05) at a concentration of 0-50 ng/mL, but NGF did not (p > 0.05), compared to untreated controls. Exogenous FGF-b and EGF promote the reprogramming of primary rat Müller cells, significantly enhancing the neural stem cell marker Nestin after stimulation on the 1st, 3rd, and 5th days, respectively. The expression of Müller cell marker Vimentin was significantly (p < 0.05) reduced during this period compared to the control group. However, there was no significant difference between the NGF and control groups. Furthermore, the EGF group expressed stronger Nestin expression than the SCM group. The Co-IF staining showed that early 50% of activated cells came from newly proliferating cells on the 5th day. These observations suggest that FGF-b can promote the activation of Müller cells in a short time and enhance the possessive features of neural stem cells, while EGF may act for a longer period of time. This may further the understanding of growth factor therapy in treating FTMHs, and Müller glia may be promising candidates for cell replacement therapy.

IL-33 Induces Paneth Cell Production of EGF and Soluble ST2, Regulating Epithelial Regeneration after Intestinal Injury

Crypt base intestinal stem cells (ISCs) maintain the epithelial lining of the intestines, but their frequencies are reduced in experimental models of graft vs. host disease (GVHD). Paneth cells provide an epithelial contribution to the stem cell niche, but their frequencies are also reduced in GVHD mouse models and in patients with GVHD. Mechanisms regulating ISCs and their niche after damage remain poorly understood. Interleukin-33 (IL-33) is an immunomodulatory alarmin typically thought to target lymphocytes such as T cells and innate lymphoid cells. In experimental models of allogeneic bone marrow transplantation, IL-33 can promote or attenuate GVHD, depending on the cellular target and the timing of the exposure. A secreted isoform of the IL-33 receptor, termed soluble ST2 (sST2), acts as a negative regulator by blocking IL-33 from binding to the membrane-bound isoform that mediates intracellular signaling. sST2 also has diagnostic and prognostic utility, serving as a biomarker for GVHD severity. While IL-33 has well-described effects on lymphocytes populations, there is limited understanding of the role of IL-33 signaling within the intestinal mucosa after damage. Utilizing experimental radiation injury to model conditioning-related intestinal pathology, we investigated the role of the IL-33/ST2 axis in epithelial damage and regeneration. Wild-type (WT) mice increased IL-33 mRNA and protein expression in the small intestine within days after 10 Gy total body irradiation (TBI). Intestinal sST2 expression also increased quickly in WT mice after TBI, but not in IL-33 -/- mice, suggesting that IL-33 itself was a regulator of sST2. While the ileal mucosa appeared similar at baseline in wild-type and IL-33 -/- mice, the IL-33 -/- mice demonstrated more severe radiation injury 5 days after 10 Gy TBI, with more crypt loss, loss of ISCs and Paneth cells, and an attenuated regenerative response with smaller crypts post-TBI containing fewer Ki67 + cells. 3-D whole-mount confocal microscopy of ileal tissue from IL-33-GFP reporter mice indicated that the crypt epithelium did not express IL-33 at baseline, but Olfm4 + ISCs adjacent to Paneth cells began to express IL-33 following radiation injury (Fig 1). Anti-Thy1-mediated lymphocyte depletion prior to irradiation of WT and IL-33 -/- mice did not abrogate the increased radiation sensitivity of IL-33 -/- mice, indicating a role for IL-33 beyond immunomodulation and suggesting that IL-33 could have direct effects within the epithelium. Intestinal organoid cultures confirmed epithelial expression of IL-33, confirmed increased radiation sensitivity of IL-33 -/- epithelium, and identified impaired epidermal growth factor (EGF) expression in the absence of IL-33. Furthermore, treatment of intestinal organoids with IL-33 induced EGF mRNA and protein expression, both of which were abrogated by the p38 inhibitor SB202190. Treatment of purified Lysozyme-DsRed + Paneth cells indicated that IL-33 directly promoted their production of EGF. In vivo, TBI-induced EGF upregulation was absent in IL-33 -/- mice. To further investigate this newly identified epithelial IL-33/ST2/EGF pathway in the ISC compartment, RiboTag mice, which facilitate analysis of lineage-specific proteome-relevant gene expression with minimal tissue processing and artifact introduction, were crossed to Olfm4-Cre and Lysozyme-Cre transgenics. Lineage-specific ribosome targeting was confirmed by immunostains and qPCR, and this approach also confirmed ISC upregulation of IL-33 following radiation injury and Paneth cell upregulation of EGF and sST2. Finally, to investigate the importance of this radiation-induced EGF upregulation, WT mice were treated with the EGFR inhibitor gefitinib following irradiation, which resulted in more severe radiation-induced ISC loss, similar to IL-33 deficiency. Furthermore, epithelial regeneration and ISC recovery were augmented in IL-33 -/- mice after TBI by treatment with exogenous EGF (Fig 2). These findings reveal an unknown pathway of stem cell niche regulation and crypt regeneration whereby the Paneth cell niche responds dynamically upon injury by upregulating EGF and the stem cells orchestrate regeneration by regulating their niche with IL-33. This regenerative circuit also highlights the breadth of IL-33 activity beyond immunomodulation and the therapeutic potential of EGF administration for treatment of intestinal injury.

Downregulation of cellular retinoic acid binding protein 1 fosters epithelial-mesenchymal transition in thyroid cancer.

Cellular retinoic acid binding protein 1 (CRABP1) participates in the regulation of retinoid signaling. Previous studies showed conflicting results regarding the role of CRABP1 in tumor biology, including protumorigenic and tumor-suppressive effects in different types of cancer. Our bioinformatics analyses suggested that CRABP1 expression was downregulated in thyroid cancer. Ectopic expression of CRABP1 in thyroid cancer cells suppressed migratory and invasive activity without affecting cell growth or cell cycle distribution. In transformed normal thyroid follicular epithelial cells, silencing of CRABP1 expression increased invasiveness. Additionally, CRABP1 overexpression was associated with downregulation of the mesenchymal phenotype. Kinase phosphorylation profiling indicated that CRABP1 overexpression was accompanied by a decrease in phosphorylation of epidermal growth factor (EGF) receptor and downstream phosphorylation of Akt, STAT3, and FAK, which were reversed by exogenous EGF treatment. Immunohistochemical analysis of our tissue microarrays revealed an inverse association between CRABP1 expression and disease stage of differentiated thyroid cancer. Taken together, our results suggest that CRABP1 expression is aberrantly lost in thyroid cancer, and this downregulation promotes the epithelial-mesenchymal transition at least partly through modulating EGF receptor signaling.

Identification of Genes Involved in EGF-induced Apoptosis Using CRISPR/Cas9 Knockout Screening: Implications for Novel Therapeutic Targets in EGFR-Overexpressing Cancers.

Exogenous epidermal growth factor (EGF) causes apoptosis in EGF receptor (EGFR)-overexpressing cell lines. The apoptosis-inducing factors could be a therapeutic target. We aimed to determine the mechanism of EGF-induced apoptosis using a genome-wide clustered regularly interspaced short palindromic repeats (CRISPR)-based knockout screen. Two-vector system of the human genome-scale CRISPR knockout library v2 was used to target 19,050 genes using 123,411 single guide RNAs (sgRNAs). Recombinant human EGF (100 nM) or distilled water four times was administered to the experimental and control groups, respectively. The read counts of each sgRNA obtained from next-generation sequencing were analyzed using the edgeR algorithm. We used another EGFR-overexpressing cell line (A549) and short hairpin RNAs (shRNAs) targeting five EGF-resistance genes for validation. DUSP1 expression in A431, A549, and HEK293FT cells was calculated using reverse transcription-quantitative polymerase chain reaction. We found 77 enriched and 189 depleted genes in the experimental group using the CRISPR-based knockout screen and identified the top five EGF-resistance genes: DDX20, LHFP, REPS1, DUSP1,<.i> and KRTAP10-12. Transfecting shRNAs targeting these genes into A549 cells significantly increased the surviving fractions after EGF treatment, compared with those observed in the control shRNA-transfected cells. The expression ratio of DUSP1 (inhibits ERK signaling) increased in A431 and A549 cells after EGF treatment. However, DUSP1 expression remained unchanged in HEK293FT cells after EGF treatment. The CRISPR-based knockout screen revealed 266 genes possibly responsible for EGF-induced apoptosis. DUSP1 might be a critical component of EGF-induced apoptosis and a novel target for EGFR-overexpressing cancers.

51P miR-4487 enhances gefitinib-mediated ubiquitination and autophagic degradation of EGFR in non-small cell lung cancer cells by targeting USP37

With the identification of epidermal growth factor receptor (EGFR) mutations in non–small cell lung cancer (NSCLC) cells, EGFR–tyrosine kinase inhibitors (TKIs) are being used widely as the first-line of treatment in NSCLC. These inhibitors block auto-phosphorylation of activated EGFR by competing with ATP binding and mediate EGFR degradation independent of exogenous epidermal growth factor, which is associated with the mutation variants of EGFR. However, the precise mechanisms underlying the TKI-mediated EGFR degradation are still unclear.

EGF Contributes to Hypertrophy of Human Ligamentum Flavum via the TGF-β1/Smad3 Signaling Pathway.

Background: The most common spinal disorder in elderly is lumbar spinal canal stenosis (LSCS). Previous studies showed that ligamentum flavum hypertrophy (LFH) with fibrosis as the main pathological change is one of the pathogenic factors leading to LSCS. Epidermal Growth Factor (EGF) is known to have an intimate relationship with fibrosis in various tissues. Nevertheless, currently, there are few studies regarding EGF in LFH. The effect of EGF on the development of LFH is unknown, and the underlying pathomechanism remains unclear. In this study, we investigated the role of EGF in LFH and its potential molecular mechanism.Methods: First, the expression levels of EGF, phosphorylation of EGF receptor (pEGFR), Transforming growth factor-β1 (TGF-β1), Phosphorylated Smad3 (pSmad3), collagen I and collagen III were examined via immunohistochemistry and Western blot in LF tissues from patients with LSCS or Non-LSCS. Second, primary LF cells were isolated from adults with normal LF thickness and were cultured with different concentrations of exogenous EGF with or without erlotinib/TGF-β1-neutralizing antibody.Results: The results showed that EGF, pEGFR, TGF-β1, pSmad3, collagen I and collagen III protein expression in the LSCS group was significantly higher than that in the Non-LSCS group. Meanwhile, pEGFR, TGF-β1, pSmad3, collagen I and collagen III protein expression was significantly enhanced in LF cells after exogenous EGF exposure, which can be notably blocked by erlotinib. In addition, pSmad3, collagen I and collagen III protein expression was blocked by TGF-β1-neutralizing antibody.Conclusions: EGF promotes the synthesis of collagen I and collagen III via the TGF-β1/Smad3 signaling pathway, which eventually contributes to LFH.

MiR-4487 Enhances Gefitinib-Mediated Ubiquitination and Autophagic Degradation of EGFR in Non-Small Cell Lung Cancer Cells by Targeting USP37.

PurposeWith the identification of epidermal growth factor receptor (EGFR) mutations in non–small cell lung cancer (NSCLC) cells, EGFR–tyrosine kinase inhibitors (TKIs) are being used widely as the first-line of treatment in NSCLC. These inhibitors block auto-phosphorylation of activated EGFR by competing with ATP binding and mediate EGFR degradation independent of exogenous epidermal growth factor, which is associated with the mutation variants of EGFR. However, the precise mechanisms underlying the TKI-mediated EGFR degradation are still unclear.Materials and MethodsTo examine the physiological roles of miR-4487 and ubiquitin-specific peptidase 37 (USP37) in gefitinib-mediated EGFR degradation in NSCLC cells, multiple NSCLC cell lines were applied. The level of EGFR expression, apoptosis marker, and autophagic flux were determined by western blot. Expression level of miR-4487 and cell-cycle arrest was analyzed by TaqMan assay and flow cytometry respectively.ResultsWe found that gefitinib mediates EGFR degradation under normal culture conditions, and is dependent on autophagic flux and the mutation variants of EGFR. Gefitinib reduced expression levels of USP37, which mediated EGFR degradation similar to gefitinib. Our results also showed a gefitinib-mediated increase in endogenous miR-4487 level and presented evidence for the direct targeting of USP37 by miR-4487, resulting in the sequential enhancement of ubiquitination, autophagy, and EGFR degradation. Thus, the depletion of USP37 and overexpression of miR-4487 led to an increase in gefitinib-mediated apoptotic cell death.ConclusionThese data suggest that miR-4487 is a potential target for treating NSCLC, and miR-4487/USP37-regulated EGFR degradation is a determinant for developing gefitinib resistance.

Knockout of c-Cbl slows EGFR endocytic trafficking and enhances EGFR signaling despite incompletely blocking receptor ubiquitylation.

Epidermal growth factor receptor (EGFR) activity is necessary and sufficient for corneal epithelial homeostasis. However, the addition of exogenous Epidermal Growth Factor (EGF) does not reliably restore the corneal epithelium when wounded. This is likely due to high levels of endogenous EGF in tear fluid as well as desensitization of the EGFR following ligand stimulation. We hypothesize that preventing receptor downregulation is an alternative mechanism to enhance EGFR signaling and promote the restoration of compromised corneas. Ligand‐dependent EGFR ubiquitylation is associated with the targeted degradation of the receptor. In this manuscript, we determine whether knockout of c‐Cbl, an E3 ubiquitin ligase that ubiquitylates the EGFR, is sufficient to prolong EGFR phosphorylation and sustain signaling. Using CRISPR/Cas9 gene editing, we generated immortalized human corneal epithelial (hTCEpi) cells lacking c‐Cbl. Knockout (KO) cells expressed the other E3 ligases at the same levels as the control cells, indicating other E3 ligases were not up‐regulated. As compared to the control cells, EGF‐stimulated EGFR ubiquitylation was reduced in KO cells, but not completely abolished. Similarly, EGF:EGFR trafficking was slowed, with a 35% decrease in the rate of endocytosis and a twofold increase in the receptor half‐life. This resulted in a twofold increase in the magnitude of EGFR phosphorylation, with no change in duration. Conversely, Mitogen Activating Protein Kinase (MAPK) phosphorylation did not increase in magnitude but was sustained for 2–3 h as compared to control cells. We propose antagonizing c‐Cbl will partially alter receptor ubiquitylation and endocytic trafficking but this is sufficient to enhance downstream signaling.

The role of exogenous epidermal growth factor on Ki-67 proliferation marker expression in the submandibular salivary gland of albino rats receiving doxorubicin

Background: This study was conducted to evaluate the role of exogenous epidermal growth factor (EGF) injection on the Ki-67 immuno-expression in submandibular salivary gland tissue of rats receiving doxorubicin (DXR). Methods: A total of 21 two-month-old male albino rats, of 200 g body weight, were divided into three groups: control group; DXR group, the rats received 20 mg/kg body weight DXR as a single intra peritoneal injection; DXR+EGF group, the rats received the same dose of DXR and on the next day they were injected intraperitoneally with 10 µg/kg body weight of EGF daily for one week. Histological sections and immunohistochemical expression of Ki67 sections were examined using a ZEISS Primo Star light microscopy and images taken using Tucsen IS 1000 10.0MP Camera. Results: Ki-67 expression was significantly increased in submandibular salivary glands of rats after DXR injection. However, Ki-67 expression in the glandular tissue was restored to normal levels after EGF injection. Conclusions: EGF preserved glandular architecture after DXR injection and maintained Ki-67 immune-expression within the glandular tissue near to the normal level.

The role of exogenous epidermal growth factor on Ki-67 proliferation marker expression in the submandibular salivary gland of albino rats receiving doxorubicin.

Background: This study was conducted to evaluate the role of exogenous epidermal growth factor (EGF) injection on the Ki-67 immuno-expression in submandibular salivary gland tissue of rats receiving doxorubicin (DXR). Methods: A total of 21 two-month-old male albino rats, of 200 g body weight, were divided into three groups: control group; DXR group, the rats received 20 mg/kg body weight DXR as a single intra peritoneal injection; DXR+EGF group, the rats received the same dose of DXR and on the next day they were injected intraperitoneally with 10 µg/kg body weight of EGF daily for one week. Histological sections and immunohistochemical expression of Ki67 sections were examined using a ZEISS Primo Star light microscopy and images taken using Tucsen IS 1000 10.0MP Camera. Results: Ki-67 expression was significantly increased in submandibular salivary glands of rats after DXR injection. However, Ki-67 expression in the glandular tissue was restored to normal levels after EGF injection. Conclusions: EGF preserved glandular architecture after DXR injection and maintained Ki-67 immune-expression within the glandular tissue near to the normal level.

Abstract 1536: MiRNA expression profile of exosomes derived from breast cancer cells following induction of the epithelial-to-mesenchymal transition

Abstract Breast cancer-derived exosomes are small extracellular vesicles that play a crucial role in the metastatic progression of breast cancer due to their ability to transport a variety of biologically active molecules (e.g., miRNAs) to local and distant sites in the body. The molecular cargo transported by breast cancer-derived exosomes alters the transcriptome of recipient cells at these sites to stimulate pro-metastatic events, including the epithelial-to-mesenchymal transition (EMT). Importantly, the molecular cargo loaded into exosomes can vary depending on cell state. However, it is unclear whether the expression of miRNAs in breast cancer-derived exosomes is altered following inducement of the EMT. Regulation of exosomal miRNAs following the EMT may enhance the ability of circulating tumor cells to target specific tissue sites or improve formation and maintenance of metastatic tumors compared to miRNAs packaged into exosomes secreted from cancer cells without induction of the EMT. To address this knowledge gap, we hypothesized that the EMT alters expression of miRNAs in exosomes derived from EMT-induced MDA-MB-468 breast cancer cells. To induce the EMT, MDA-MB-468 cells were treated with exogenous epidermal growth factor. MDA-MB-468 cells treated with epidermal growth factor exhibited greater mRNA expression of the mesenchymal marker Vimentin compared to non-treated MDA-MB-468 cells by qRT-PCR. Subsequently, exosomes were isolated from the conditioned cell culture medium of MDA-MB-468 cells, with and without induction of the EMT, using ExoQuick exosome isolation reagent. Molecular size analysis of isolated exosomes revealed that they were similar in size to the typical size range reported for exosomes (40 - 150nm). Moreover, a common exosomal marker protein, CD9, was enriched in the MDA-MB-468-derived exosome fractions compared to whole cell lysates by Western blot. Furthermore, next generation sequencing and bioinformatic analysis were performed to determine the miRNA expression profiles of these exosomes. Results from this study reveal expression of miRNAs in breast cancer cell-derived exosomes before and after activation of the EMT and may indicate how exosomes secreted from advanced stage breast cancer enhance metastatic tumor progression. Citation Format: Christian A. Showalter, Yinan Huang, Monica M. Burdick. MiRNA expression profile of exosomes derived from breast cancer cells following induction of the epithelial-to-mesenchymal transition [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 1536.

GLP-2, EGF, and the Intestinal Epithelial IGF-1 Receptor Interactions in the Regulation of Crypt Cell Proliferation.

Glucagon-like peptide-2 (GLP-2) is an intestinotrophic hormone that promotes intestinal growth and proliferation through downstream mediators, including epidermal growth factor (EGF) and insulin-like growth factor-1 (IGF-1). EGF synergistically enhances the proliferative actions of IGF-1 in intestinal cell lines, and both of these factors are known to be essential for the trophic effects of GLP-2 in vivo. However, whether EGF and IGF-1 interact to mediate the proliferative actions of GLP-2 in vivo remains unknown. Normal and knockout (KO) mice lacking the intestinal epithelial IGF-1 receptor (IE-IGF-1R) were therefore treated chronically with EGF and/or long-acting human hGly2GLP-2, followed by determination of intestinal growth parameters. Intestines from control and IE-IGF-1R KO mice were also used to generate organoids (which lack the GLP-2 receptor) and were treated with EGF and/or IGF-1. Combination treatment with EGF and hGly2GLP-2 increased small intestinal weight and crypt-villus height in C57Bl/6 mice in an additive manner, whereas only hGly2GLP-2 treatment increased crypt cell proliferation. However, although combination treatment also increased small intestinal weight and crypt-villus height in IE-IGF-1R KO mice, the proliferative responses to hGly2GLP-2 alone or with EGF were diminished in these animals. Finally, IGF-1 treatment of organoids undergoing EGF withdrawal was not additive to the effect of EGF replacement on proliferation, but could restore normal proliferation in the absence of EGF. Together, these findings demonstrate that the intestinal proliferative effects of hGly2GLP-2 are augmented by exogenous EGF in a manner that is partially dependent upon IE-IGF-1R signaling.

Interaction of epidermal growth factor with COX-2 products and peroxisome proliferator-activated receptor-γ system in experimental rat Barrett's esophagus.

Mixed acidic-alkaline refluxate is a major pathogenic factor in chronic esophagitis progressing to Barrett's esophagus (BE). We hypothesized that epidermal growth factor (EGF) can interact with COX-2 and peroxisome proliferator-activated receptor-γ (PPARγ) in rats surgically prepared with esophagogastroduodenal anastomosis (EGDA) with healthy or removed salivary glands to deplete salivary EGF. EGDA rats were treated with 1) vehicle, 2) EGF or PPARγ agonist pioglitazone with or without EGFR kinase inhibitor tyrphostin A46, EGF or PPARγ antagonist GW9662 respectively, 3) ranitidine or pantoprazole, and 4) the selective COX-2 inhibitor celecoxib combined with pioglitazone. At 3 mo, the esophageal damage and the esophageal blood flow (EBF) were determined, the mucosal expression of EGF, EGFR, COX-2, TNFα, and PPARγ mRNA and phospho-EGFR/EGFR protein was analyzed. All EGDA rats developed chronic esophagitis, esophageal ulcerations, and intestinal metaplasia followed by a fall in the EBF, an increase in the plasma of IL-1β, TNFα, and mucosal PGE2 content, the overexpression of COX-2-, and EGF-EGFR mRNAs, and proteins, and these effects were aggravated by EGF and attenuated by pioglitazone. The rise in EGF and COX-2 mRNA was inhibited by pioglitazone but reversed by pioglitazone cotreated with GW9662. We conclude that 1) EGF can interact with PG/COX-2 and the PPARγ system in the mechanism of chronic esophagitis; 2) the deleterious effect of EGF involves an impairment of EBF and the overexpression of COX-2 and EGFR, and 3) agonists of PPARγ and inhibitors of EGFR may be useful in the treatment of chronic esophagitis progressing to BE.NEW & NOTEWORTHY Rats with EGDA exhibited chronic esophagitis accompanied by a fall in EBF and an increase in mucosal expression of mRNAs for EGF, COX-2, and TNFα, and these effects were exacerbated by exogenous EGF and reduced by removal of a major source of endogenous EGF with salivectomy or concurrent treatment with tyrphostin A46 or pioglitazone combined with EGF. Beneficial effects of salivectomy in an experimental model of BE were counteracted by PPARγ antagonist, whereas selective COX-2 inhibitor celecoxib synergistically with pioglitazone reduced severity of esophageal damage and protected esophageal mucosa from reflux. We propose the cross talk among EGF/EGFR, PG/COX-2, and proinflammatory cytokines with PPARγ pathway in the mechanism of pathogenesis of chronic esophagitis progressing to BE and EAC.

Epidermal growth factor attenuates lingual papillae lesions in a rat model of sialoadenectomy

Salivary epidermal growth factor (EGF) plays an important role in the maintenance of the oral and gastro-esophageal mucosa. Sialoadenectomy delays healing of oral wounds and affects lingual papillae. In this work, we aimed to determine the effect of EGF deficiency induced by sialoadenectomy and evaluate the effect of exogenous EGF administration on the lingual papillae and taste buds in rats. Thirty male adult Wistar albino rats were equally divided into 3 groups; sham-operated control group, sialoadenectomy group and group of sialoadenectomy + EGF. EGF was given 8 weeks after sialoadenectomy in a dose of 1 μg /ml/day in drinking water for 2 weeks. The anterior two-thirds of the tongue was dissected and cut longitudinally into two halves; one half for light microscope and the other for electron microscope examinations. Saliva and blood were collected to determine salivary and plasma EGF. Our results revealed that sialoadenectomy significantly reduced plasma and saliva levels of EGF which resulted in severe disruption of the architecture of lingual papillae. These changes were effectively improved by the exogenous EGF administration. In conclusion, EGF supplementation reversed the effects of sialoadenectomy and restored almost normal architecture of lingual papillae and taste buds.

Epidermal growth factor protects against myocardial ischaemia reperfusion injury through activating Nrf2 signalling pathway

Alleviating the oxidant stress associated with myocardial ischaemia reperfusion has been demonstrated as a potential therapeutic approach to limit ischaemia reperfusion (I/R)-induced cardiac damage. It is reported that EGFR/erbB2 signalling is an important cardiac survival pathway in cardiac function and activation of EGFR has a cardiovascular effect in global ischaemia. Epidermal growth factor (EGF), a typical EGFR ligand, was considered to have a significant role in activating EGFR. However, no evidence has been published whether exogenous EGF has protective effects on myocardial ischaemia reperfusion. This study aims to investigate the effects of EGF in I/R-induced heart injury and to demonstrate its mechanisms. H9c2 cells challenged with H2O2 were used for in vitro biological activity and mechanistic studies. The malondialdehyde (MDA) and Superoxide Dismutase (SOD) levels in H9c2 cells were determined, and the cell viability was assessed by MTT assay. Myocardial I/R mouse administrated with or without EGF were used for in vivo studies. Pretreatment of H9c2 cells with EGF activated Nrf2 signalling pathway, attenuated H2O2-increased MDA and H2O2-reduced SOD level, followed by the inhibition of H2O2-induced cell death. In in vivo animal models of myocardial I/R, administration of EGF reduced infarct size and myocardial apoptosis. These data support that EGF decreases oxidative stress and attenuates myocardial ischaemia reperfusion injury via activating Nrf2.

Different levels of epidermal growth factor signaling modifies the differentiation of specific cell types in mouse postnatal retina

Epidermal growth factor (EGF) signaling has been implicated in the regulation of the differentiation and proliferation of retinal progenitors. We assessed how different levels of EGF signaling, achieved either by increasing receptor expression or via addition of the exogenous ligand, or an increase in both, can affect the differentiation of progenitors in the first week of postnatal retinal development in the model system of retinal explants (REs). Proliferating progenitor cells in REs were infected with either the control CLV3/ESR-related peptide family (CLE)-green fluorescent protein (GFP)- or with EGF receptor (EGFR)-GFP-expressing retrovirus, and grown in the control medium or in the presence of exogenous EGF (10 ng/mL). The differentiation of infected cells into Muller glia (Sox9+), rod photoreceptors (rhodopsin+) and horizontal cells (calbindin+) was analyzed. In all the examined conditions, infected cells differentiated into Muller glia and rod photoreceptors that normally develop postnatally. Horizontal cells finished their development during the embryonic stages and progenitors infected with control-GFP virus did not differentiate into GFP+/calbindin- in either control or EGFsupplemented medium, however, cells infected with EGFR-GFP differentiated into horizontal cells (GFP+/calbindin+) in both culture conditions. These results imply that altering the levels of EGFR and/or the amount of the EGF ligand can overcome progenitor competence restriction.

Therapeutic effect of the epidermal growth factor on diabetic foot ulcer and the underlying mechanisms.

The present study aimed to explore the therapeutic effect and underlying mechanism of epidermal growth factor (EGF) on the wound healing of diabetic foot ulcers (DFU). A total of 48 rabbits with DFU were randomly divided into 2 groups, comprising the treatment and control groups. Full-thickness skin (10×10 mm) was excised from the thigh of each rabbit. The wounds in the treatment group were treated with 100 mg/l EGF once a day for 1 month. The control group received no treatment. At 20 days following treatment, new granulation tissues that formed beyond the edge of the wound were collected for subsequent analysis. Tissues from rabbits in the treatment group produced a greater number of fibroblasts, which exhibited a fibroblastic morphology when compared with those in the control group. In the treatment group, a larger number of these fibroblasts were observed as clusters, and there were numerous blood vessels when compared with the control group. The fibroblasts in the control group exhibited an irregular morphology, contained fewer organelles and the surrounding collagenous fibers were sparse. These fibroblasts also demonstrated a disordered arrangement and it was revealed that the wound healed at a slower rate compared with the treatment group. Endogenous EGF mRNA detection revealed that there was a significant difference (P<0.05) in the relative gray value of EGF mRNA between the treatment (103.27±4.27) and control (63.88±4.36) groups. In conclusion, EGF may accelerate the healing of DFU, and exogenous EGF treatment may upregulate the expression of EGF mRNA in newly generated tissues.

Invited commentary

Preventing the advancement of or, better yet, reversing peripheral vascular occlusive disease could save many limbs and provide a better quality of life for our patients. The “magic bullet” of an individual agent placed locally to change the milieu sufficiently to improve collateral vascular development or to stimulate angiogenesis has not been successful to date. However, providing cells that can change the local milieu by providing a slurry of beneficial agents is more promising. Mesenchymal stem cells (MSCs) can provide stromal support and paracrine effects of potential benefit. Unfortunately, one group of patients who could benefit most are those with diabetes, and yet their MSCs (dMSCs) have a deficient expansion capacity. This paper tests the hypothesis that dMSCs have a reversible defect in the epidermal growth factor (EGF) receptor pathway that may blunt cell growth and survival. Human platelet lysate (PL), known to be rich in several growth factors including EGF, might reverse this deficiency, as might EGF alone. It tests whether dMSCs can provide angiogenic stimulus of human umbilical vein endothelial cells (ECs) and, therefore, be a viable regenerative treatment. The study demonstrates that MSCs from the bone marrow and adipose tissue of limbs of well-controlled, nonsmoking diabetic patients have similar population doublings and entered senescence after passage 11, confirming deficient expansion capacity. In addition, dMSCs do not express EGF in their secretome while demonstrating robust expression of other angiogens. Supplementing the dMSCs with PL increased phosphorylation of AKT to healthy MSC levels, whereas providing EGF alone increased only phosphorylated extracellular signal-regulated protein kinases 1 and 2 (ERK1/2) to similar levels as that of PL supplementation. MSC invasion increased over time, but there were inconsistent differences of invasion length and chemokine concentration across MSC types and patients. Both cell types were able to stimulate EC proliferation like standard EC growth media and in co-culture demonstrated longer EC sprouts. In contrast to past literature, this study confirms a lack of EGF expression by dMSCs, providing a deficiency that is cell culture modifiable. Adding EGF increased phosphorylated ERK1/2 levels but not pAKT levels, whereas PL increased both, which may be important because both AKT and ERK1/2 signaling pathways promote cell survival, proliferation, and sustained paracrine activity. The lack of EGF may explain the early senescence noted in the study, but exogenous EGF certainly does not fully correct deficient signaling pathways, whereas PL does better but likely not totally in considering prior studies by the same authors. Both types of dMSCs promote EC proliferation and sprouting, which supports the regenerative benefits of these cells if sufficient numbers for local injection are available. This study has limitations regarding sample size, potential lack of generalization (the population was nonsmoking, well-controlled diabetic patients), and potential bias because the control MSCs were from the iliac crest whereas the experimental MSCs were from the tibia. Provided is some detailed explanation as to how these limitations can be interpreted. Overall, this study is another step forward in the basic science wheel of evidence that will eventually lead to a clinical advancement in regenerative medicine aimed at limb salvage. The opinions or views expressed in this commentary are those of the author and do not necessarily reflect the opinions or recommendations of the Journal of Vascular Surgery the Society for Vascular Surgery. Reversible secretome and signaling defects in diabetic mesenchymal stem cells from peripheral arterial disease patientsJournal of Vascular SurgeryVol. 68Issue 6PreviewRegenerative medicine seeks to stall or to reverse the pathologic consequences of chronic diseases. Many people with diabetes have peripheral arterial disease (PAD), which increases their already high risk of major amputation. Cellular therapies are a promising regenerative medicine approach to PAD that can be used to focally inject regenerative cells to endangered tissue beds. Mesenchymal stem cells (MSCs) are known to promote tissue regeneration through stromal support and paracrine stimulation of new blood vessels (angiogenesis). Full-Text PDF Open Archive

HER2 Activation Factors in Arsenite-Exposed Bladder Epithelial Cells.

Chronic exposure to arsenic in drinking water is associated with an increased risk of bladder cancer in arseniasis-endemic areas throughout the world. Human epidermal growth factor receptor 2 (HER2) was recently reported to be involved in the development of bladder cancer. However, until this point, little is known about HER2 activation and its mechanism in arsenite-exposed urothelial cells. The aim of this study was to identify factors associated with HER2 activation in an arsenite-exposed human bladder epithelial cell line. Results of this study demonstrated that levels of phosphorylated HER2 increased significantly in cells treated with arsenite. Additionally, the protein levels of epidermal growth factor (EGF), transforming growth factor α (TGFα), soluble ectodomain fragment of E-cadherin (sE-cad), and neuregulin 1 (NRG1) were also increased significantly in these cells. Meanwhile, the protein levels of heat shock protein 90 (HSP90) and plasma membrane calcium ATPases 2 (PMCA2) increased, while those of Interleukin-6 (IL-6) and N-myc downstream regulated gene 1 (NDRG1) decreased significantly. Pretreatment of arsenite-exposed cells with exogenous EGF, TGFα, NRG1, and HSP90 could promote, whereas exogenous IL-6 and NDRG1 could suppress, the phosphorylation of HER2. Furthermore, reduction of EGF, TGFα, NRG1, PMCA2, or HSP90 via its neutralizing antibody, siRNA, or inhibitor suppressed, whereas knockdown of E-cadherin promoted, the phosphorylation of HER2. In conclusion, our results suggested that HER2 might be activated through promoting the dimerization of HER2 with other members of HER family, maintaining the stability of phosphorylated HER2, and attenuating the suppression of HER2 activation in arsenite-exposed cells.

Abstract 2029: Notch signaling inhibitor increases E-selectin/ligand interactions and alters cell migration of mesenchymal-like breast cancer cells

Abstract Activation of Notch signaling has been shown to promote cell migration properties and hematogenous metastasis by inducing a dramatic phenotypic change in breast cancer cells via the epithelial-to-mesenchymal transition (EMT). In response to these findings, Notch signaling inhibitors are being explored as therapeutics to prevent EMT in cancers. However, research examining the effects of Notch inhibitors on the activity of sialofucosylated ligands used by circulating tumor cells to adhere to vascular endothelial E-selectin during metastasis is lacking. To advance knowledge in this area, our study investigated the use of an indirect Notch signaling inhibitor (DAPT) on modifying E-selectin ligand activity of breast cancer cell lines by shear flow adhesion assays performed at physiological bone marrow shear stress. DAPT exposure to mesenchymal-like MDA-MB-231 and MDA-MB-468 (induced to the mesenchymal-like state by exogenous epidermal growth factor) breast cancer cells increased E-selectin ligand activity. Furthermore, mesenchymal-like MDA-MB-468 cells after DAPT exposure demonstrated E-selectin ligand activity similar to that of epithelial-like MDA-MB-468 cells. This supports the hypothesis by our group that epithelial-like and mesenchymal-like phenotypes determine activity of functional E-selectin ligands in breast cancer cells, as we have previously shown that epithelial cells display high E-selectin ligand activity while mesenchymal cells display little or no ligand activity. Cell migration ability was assessed using wound closure assays. Mesenchymal-like MDA-MB-468 cells exposed to DAPT exhibited decreased migration compared to mesenchymal-like MDA-MB-468 cells exposed to the DMSO diluent control, whereas mesenchymal-like MDA-MB-231 cells demonstrated no difference in migration compared to DMSO exposed cells. Altogether, our results suggest Notch inhibitors may both increase fluid-shear resistant adhesion and alter migration ability of mesenchymal-like breast cancer cells, and that factors present in the blood might impact the metastatic potential of cancer cells via regulating cellular phenotypes. Citation Format: Christian A. Showalter, Monica M. Burdick. Notch signaling inhibitor increases E-selectin/ligand interactions and alters cell migration of mesenchymal-like breast cancer cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 2029.