Epidermal growth factor-urogastrone, a polypeptide acquiring hormonal status

Mammalian epidermal growth factor promotes plant growth

Application of mouse submaxillary gland epidermal growth factor to young sorghum seedlings at low concentrations ( approximately 0.4-4 muM) increased shoot growth significantly over 3- and 6-day periods. The effects were dose dependent.

Epidermal growth factor: a critical factor in fetal maturation?

Epidermal growth factor (EGF) infused over 3-14 days into fetal sheep of 110-125 days gestation resulted in a number of morphological and endocrine changes. Striking hypertrophy of the skin, wool follicles and their accessory structures was seen, together with a reduction in the ratio of secondary to primary follicles and degenerative changes in wool fibres associated with shedding of fibres. Adrenal, thyroid, liver and kidney weights were increased while thymus weight was decreased. The increase in adrenal size resulted from cortical hypertrophy and was associated with increased cortisol secretion. Thyroid hypertrophy was accompanied by an increase in colloid stores, decreased plasma thyroxine and reverse triiodothyronine (T3) concentrations, unchanged plasma T3 and thyroid-binding globulin and raised thyrotropin (TSH) levels. Thyrotropin receptor affinity and content per gram of tissue were unchanged. Fetal and maternal plasma prolactin and growth hormone levels, and fetal plasma placental lactogen levels, were unchanged, although there was a significant rise in maternal plasma placental lactogen concentrations with high doses of EGF. Other maturational parameters such as switching from fetal to adult haemoglobin and liver glycogen content were unaffected.

Insulin-like growth factor I, epidermal growth factor and transforming growth factor beta expression and their association with intrauterine fetal growth retardation, such as development during human pregnancy

AIM

Fetal intrauterine growth retardation (IUGR) is one of the most common obstetric problems, with a frequency of 12% in Mexico. In the past, investigations have focused on extrinsic causes of IUGR. More recent studies have examined the intrinsic factors that cause fetal intrauterine growth. Maintenance of fetal growth has been attributed to insulin-like growth factor (IGF), epidermal growth factor (EGF) and transforming growth factor beta (TGF-beta). The objective of this study was to assess the levels of these growth factors during pregnancy and to determine whether or not low concentrations are associated with IUGR.

METHODS

Nine women whose pregnancies were complicated by IUGR and a group of nine women whose pregnancies exhibited normal fetal intrauterine growth were studied. IUGR was determined by sonography and confirmed by weight at birth. Venous blood samples were taken from both groups of pregnant women at the end of each trimester. Enzyme-linked immunosorbent assays, immunoradiometric assays and radioimmunoassays were used to process samples, and the results were analysed by anova.

RESULTS

IGF-I levels increased in both groups during pregnancy, but the increase was lower (p < 0.001) in the IUGR group throughout pregnancy and at delivery. EGF did not show any significant changes during pregnancy. Blood TGF-beta levels varied only during the first trimester of pregnancy. The differences were not statistically significant. However, TGF-beta concentrations were higher in the pregnancies with IUGR. Women in the IUGR group were smaller than in the control group (p < 0.05), and, using the covariance test (p < 0.05), this was found to be correlated with IGF-I levels but not with EGF or TGF-beta levels.

CONCLUSIONS

Changes in fetal weight might be explained by the different concentrations of IGF. The structural homology between IGF-1 and insulin could mean that the presence of higher levels of IGF would result in a increased energetic metabolism that could contribute to fetal growth. EGF levels were not related to IUGR, and TGF-beta levels increased only during the first 3 months in the IUGR group. This observation correlates with the in vitro action of TGF-beta as a negative factor of growth, but as a positive support for sustaining early pregnancy. Our data illustrates that low height represents an increased risk factor for IUGR. These data also correlate with the studies involving extrinsic factors.

Anionic mucoadhesive polymers as auxiliary agents for the peroral administration of (poly)peptide drugs: influence of the gastric juice

The incorporation of (poly)peptide drugs in mucoadhesive polymers is a promising strategy for their peroral administration. In this study, the protective effect of various polymers toward an artificial gastric fluid and the influence of an enteric coating on the adhesive properties have been investigated. Tablets containing 30 mg of carbomer (C934P), neutralized carbomer (NaC934P), or sodium carboxymethylcellulose (NaCMC), 0.1 mg of the model protein peroxidase, and 19.9 mg of mannitol were incubated at 37 degrees C for 2.5 hr with a simulated gastric fluid with and without pepsin. All polymers--although anionogenic--displayed quick swelling behavior in the acid milieu, leading to an unintended protein release. Moreover, pepsin is capable of penetrating into the polymeric carrier systems, thereby rapidly degrading the embedded protein. Enteric coating, on the other hand, leads to strongly reduced adhesive properties. Only NaC934P tablets coated with polymethacrylate containing 9% triethylcitrate displayed no significant (p < .05) reduction in adhesive strength. Results give essential basic information for the development of peroral (poly)peptide dosage forms based on mucoadhesive polymers.

Effect of endogenous and exogenous EGF on the growth of EGF receptor-hyperproducing human squamous cell carcinoma implanted in nude mice

The effect of epidermal growth factor (EGF) on the biological behaviour of human tumours in vivo is still controversial. We investigated the effect of EGF on the growth of an EGF receptor-hyperproducing human epidermoid carcinoma, A431 tumour, and on a human small-cell lung carcinoma, H69 tumour, without detectable EGF receptor by using sialoadenectomised (sialex) mice as an endogenous EGF-suppressed animal model. The plasma EGF concentration in the sialex athymic mice was significantly lower than that in the sham-operated mice (P < 0.05). After exogenous EGF replacement with an implanted minipump, the plasma EGF concentration was significantly increased in both groups (P < 0.05). There was no significant difference between the body weight growth curves of sialex and sham-operated mice with and without EGF treatment. The tumour weight of A431, both estimated and measured in sialex mice, was significantly lower than that in sham-operated control mice (P < 0.05), and the growth of A431 tumour was significantly increased by exogenous EGF treatment (P < 0.05). Mitotic activity of these tumours detected by immunohistochemical staining for incorporated bromodeoxyuridine indicated a mitosis-stimulatory effect of endogenous and exogenous EGF on A431 tumours. In contrast to these findings on A431 tumours, a growth-stimulatory effect of endogenous and exogenous EGF was not observed in the H69 tumour. These results suggest a growth-promoting effect of physiological levels of endogenous EGF on EGF receptor-hyperproducing human tumours in vivo.

Effect of secretin and somatostatin on secretion of epidermal growth factor from Brunner's glands in the rat

The effect of secretin and somatostatin on secretion of epidermal growth factor (EGF) from Brunner's glands was investigated in rats. Secretin increased volume secretion and the median output of EGF rose from 720 fmol/5 hr (total range 460-1320) in controls to 2065 fmol/5 hr (total range 1560-2730) at a dose of 50 pmol/kg/hr of secretin. Somatostatin inhibited Brunner's gland secretion, but the total output of EGF remained unchanged. Secretin-stimulated volume secretion and secretion of EGF was significantly reduced by simultaneous infusion of somatostatin. This study has shown that secretin stimulates secretion of EGF as well as volume secretion from Brunner's glands. Somatostatin prevents the effect of secretin on Brunner's glands, which suggests a role for somatostatin in control of Brunner's gland secretion.

Chronoimmunohistochemical localization of epidermal growth factor in the submandibular gland of male rats

Chronobiological oscillation was established for epidermal growth factor (r-EGF) in granular convoluted tubule (GCT) cells of the male rat submandibular gland (SMG) using immunohistochemistry. The high amplitude oscillation with a peak at 9 p.m. and low amplitude oscillation during the day time was noted. The distribution pattern of the r-EGF in the GCT segment was time-dependent, as it was seen at 3 p.m. when many cells with r-EGF staining were detectable. The higher reactivity during the activity phase of the rats may correlate with the intracellular biosynthesis of r-EGF required for cell proliferation and maintenance of ductal integrity. The chronobiological oscillation pattern of r-EGF seems to be important for the maintenance of ductal integrity and wound healing.

Effect of epidermal growth factor by different routes of administration on the small intestinal mucosa of rats fed elemental diet

This study was undertaken to investigate the effect of epidermal growth factor (EGF) on the rat small intestinal mucosa by three different routes of administration. Four-week-old rats were fed elemental diet for 4 weeks and were administered EGF either subcutaneously, intraluminally or intraperitoneally with mini-osmotic pumps for a week. Intraperitoneal administration of EGF resulted in a significant increase of mucosal wet weight, mucosal content of protein and DNA, villus height, crypt depth and crypt cell production rate. Intraluminal or subcutaneous administration of EGF tended to increase those morphological and proliferative parameters, but did not cause any significant change. We conclude that EGF caused the hyperplasia of the small intestine of rats maintained on oral elemental diet and that this trophic effect was clearly shown by the intraperitoneal route of administration, rather than by the intraluminal route. These results suggest that EGF receptors located in the basal portion of crypt cells play a more important role than those located in the microvillous membrane.

Synergistic actions of epidermal growth factor-urogastrone and vasopressin in cultured aortic A-10 smooth muscle cells

In cultured rat aorta-derived A-10 cells, epidermal growth factor-urogastrone (EGF-URO) acts synergistically with arginine vasopressin (AVP) to augment the AVP-mediated release of 3H-arachidonate (3H-AA) from 3H-AA prelabeled cells. On its own, EGF-URO had no effect on AA release and had no effect on calcium influx or efflux either in the absence or presence of AVP. The synergistic action of EGF-URO was not affected by actinomycin D, cycloheximide, indomethacin, by the diacylglycerol lipase inhibitor U-57,908, or by the tyrosine kinase inhibitors genistein (GS) and tyrphostin (TP). TP did, nonetheless, completely abrogate 3H-thymidine incorporation triggered in the presence of EGF-URO. Although EGF-URO stimulated an increase in calpactin-II (lipocortin-I) phosphorylation in permeabilized cells, no such increase was detected in intact cells exposed to EGF-URO either alone or in combination with AVP, under conditions where EGF-URO augmented the action of AVP. The phospholipase A2 inhibitor, mepacrine, had no effect on AVP-mediated AA release, but abolished the synergistic action of EGF-URO. We conclude that in contrast with our previous results with gastric smooth muscle strips, wherein EGF-URO acts via the diacylglycerol lipase-mediated metabolism of diacylglycerol, and in keeping with observations with cultured mesangial cells, EGF-URO acts synergistically with AVP in A-10 cells via the activation of phospholipase A2. This synergistic action of EGF-URO does not appear to be due to increased levels of cyclooxygenase and would appear not to require increased tyrosine kinase activity.

Stimulatory effect of epidermal growth factor on liver regeneration after partial hepatectomy in rats

The effect of epidermal growth factor (EGF) on liver regeneration was investigated in rats subjected to partial hepatectomy. In a dose-response study EGF in doses of 6 and 24 nmol/kg x day increased liver regeneration after treatment for 48 h compared with controls, whereas a dose of 48 nmol/kg x day had no effect. In a subsequent study EGF, 6 nmol/kg x day, accelerated liver regeneration significantly after 36, 48, and 72 h of treatment. A possible influence of EGF on other hepatotrophic factors was investigated. No changes in the concentration of gastrin, insulin, or glucagon was found in portal venous blood. This study has shown that EGF in small doses can stimulate liver regeneration, whereas higher doses are ineffective. The study suggests that EGF should be regarded as a hepatotrophic factor.

Production and characterization of mammary-derived growth factor 1 in mammary epithelial cell lines

A mammary-derived growth factor, MDGF1, which stimulates collagen synthesis and proliferation in mammary epithelial cells was previously detected and purified from human milk and primary human breast tumors. MDGF1 binds to putative cell-surface receptors of 120-140 kDa and stimulates proliferation of normal and malignant human mammary epithelial cells. Partial protein sequence (N-terminal 18 amino acid sequence) shows that MDGF1 has no homology to any other known growth-promoting peptides. Polyclonal antiserum raised against this synthetic peptide recognizes native milk-derived MDGF1. We hypothesize that MDGF1 might be an autocrine or paracrine factor produced by and acting on normal and malignant human breast epithelial cells possessing MDGF1 receptors. As a first step in testing this possibility, we examined whether human breast epithelial cells in culture produce the growth factor. A protein with the size of MDGF1 was immunologically detected in the concentrated conditioned medium prepared from human breast cancer cell line MDA-MB 231, the mammary-derived but nontumorigenic HBL-100 line, and the normal reduction mammoplasty-derived, nonimmortalized 184 cell strain. A competitive radioreceptor assay (RRA) was used to estimate the level of MDGF1 in the conditioned medium. MDGF1 was present in the nanogram range per 1 million cells. A 62-kDa protein was detected in the above cell lysates by Western immunoblotting or by immunoprecipitation of metabolically labeled cell-conditioned media. The polyclonal antisera directed against the 18 amino acid peptide sequence from milk-derived MDGF1 could adsorb MDGF1 biological activity from conditioned medium. In vitro translation of cell mRNA yielded a protein of 55 kDa which was immunoprecipitated by anti-MDGF1 antibody.(ABSTRACT TRUNCATED AT 250 WORDS)

Variation of hydrophobicity of human urinary epidermal growth factor

Epidermal growth factor is present in human urine in large amounts, but its biological significance is not known. The results of this study indicate that the predominant 6000-dalton form of epidermal growth factor in human urine is divided by hydrophobic interaction chromatography into four fractions; only 3% of the total 6000-dalton epidermal growth factor coeluted with the biosynthetic epidermal growth factor and the rest was separated into three different peaks. These different forms may lack one or two amino or carboxy terminal amino acids from the 53 amino acids present in epidermal growth factor, or they may be products of deamidation or oxidation of amino acid(s). Further knowledge of these micromodifications of epidermal growth factor secreted in urine may reveal the origin and function of epidermal growth factor in humans.

Decreased urinary epidermal growth factor levels in diabetic patients

Urinary human epidermal growth factor levels were assayed in diabetic patients and controls before and after surgery. The preoperative levels in the diabetic patients were decreased and postoperatively, did not show the trough and peak pattern which was seen in the controls.

Histological studies on eyelid opening in normal male mice and hemizygotes for the mutant gene Tabby (Ta) with and without epidermal growth factor treatment

Previous work has shown that mice hemizygous or homozygous for the mutant gene Tabby have delayed eyelid opening, as compared to unaffected, wildtype littermate controls; exogenous treatment with epidermal growth factor reverses this delay. We performed histological studies to explore the mechanisms of action of the Tabby gene and of epidermal growth factor in these processes. These show that eyelid opening is associated with keratinization of the fusion junction and conjunctival sac formation. Both these processes occur earlier in normal male mice (days 4 and 7 respectively) than in Tabby hemizygotes (days 7 and 10, respectively). After epidermal growth factor injection, keratinization and conjunctival sac formation are both observed on postnatal day 1 in all control and mutant pups. Thus epidermal growth factor appears to accelerate eyelid opening by stimulating these morphological processes and the Tabby gene appears to delay eyelid opening by impairing them. It is possible that deficiency of epidermal growth factor at the tissue level may be involved in the development of some of the traits seen in Tabby mutants. In addition to analysing the effects of the Tabby gene and of epidermal growth factor on eyelid opening in the mouse, this study appears to be the first detailed histological description of normal eyelid opening. The findings have potential clinical significance; firstly, because the Tabby gene shows genetic homology to the human gene for hypohidrotic ectodermal dysplasia, and disturbed eyelid opening is a trait of some forms of human ectodermal dysplasia, and secondly, because the gene for epidermal growth factor receptor is an oncogene.

Effect of epidermal growth factor (EGF) on gluconeogenesis in isolated rat hepatocytes. Dependency on the red-ox state of the substrate

It was found that EGF decreased both the basal- and the glucagon-stimulated gluconeogenesis from lactate alone or from a high lactate/pyruvate ratio and that it enhanced both the basal- and the glucagon-inhibited glucose synthesis from pyruvate alone or from a low lactate/pyruvate ratio. These findings demonstrate that the effect of both EGF and glucagon on glucose production by isolated hepatocytes depends on the red-ox state of the substrate.

Immunolocalization of epidermal growth factor (EGF), EGF receptor and transforming growth factor alpha (TGF alpha) during murine palatogenesis in vivo and in vitro

The distribution of epidermal growth factor, the epidermal growth factor receptor and transforming growth factor alpha during murine palatogenesis was investigated immunocytochemically. On embryonic day 12 staining for transforming growth factor alpha was present throughout the palatal mesenchyme, with little in the epithelia. On embryonic day 13 staining increased in the palatal epithelia and in the mesenchyme at the tip of the palate. As the palatal shelves fused together (embryonic day 14.5) intense staining for transforming growth factor alpha was seen in the midline epithelial seam and in the subjacent mesenchyme. On embryonic day 15 there was a generalised increase in palatal epithelial staining; this was most marked in the remnants of the degenerating epithelial seam. Mesenchymal staining was, however, uniform. Whilst palatal staining for epidermal growth factor was sparse, at all stages, staining for its receptor was present throughout the palatal epithelia and mesenchyme. This was most intense in the palatal medial edge epithelia at the time of midline epithelial seam degeneration. The regional and temporal differences in staining for the epidermal growth factor receptor and transforming growth factor alpha suggested that these molecules may play an important role in normal palate development in vivo, particularly in degeneration of the midline epithelial seam.

Characterization of epidermal growth factor receptor in normal and neoplastic human endometrium

Growth factors, including epidermal growth factor (EGF), have been implicated in the growth of several types of cancer. This study compares EGF receptors in normal and neoplastic endometrium. Membrane fractions were isolated from surgical specimens. Radioreceptor assays demonstrated the presence of receptors with a dissociation constant of 0.64 nmol/l in normal endometrium. Affinity cross-linking revealed receptor molecular weight of 150 to 170 kiloDaltons (KD). A survey of samples (n = 37) revealed progressive decrease of EGF receptors in cancers of increasing grade: Grade 1-2 adenocarcinoma decreased 34% from control (n = 6, P less than 0.01), whereas Grade 3 adenocarcinoma decreased 90% (n = 7, P less than 0.01) and sarcoma decreased by 72% (n = 3, P less than 0.01). The dissociation constant and molecular weight of the receptor in neoplastic endometrium did not differ significantly from normal. The inverse relationship with grade suggests receptor alteration or down regulation by hormones and/or growth factors.

Metabolism of i.v. administered 45 kDa epidermal growth factor in the rat

The 45 kDa epidermal growth factor (EGF-(45 kDa)) has been purified from rat urine. We have investigated the distribution and the processing of i.v. injected 125I-labeled EGF-(45 kDa) in the rat. 2.5 min after the i.v. injection only 12% of the label remained in the blood. Most of the label was found in the liver (54%), in the kidneys (7%) and in the skin (4%). The submandibular glands, stomach, small intestine, colon, spleen and lungs contained 1% or less of the radioactivity. Some of the 125I-EGF-(45 kDa) was processed to 125I-EGF-(6 kDa) immunoreactivity in the liver and in the kidneys. The kidneys excreted 125I-EGF-(45 kDa) in the urine, but we were not able to demonstrate 125I-EGF-(6 kDa) in urine. In conclusion, this study shows that homologous EGF-(45 kDa) is cleared from the circulation of rats within a few minutes, mainly by the liver and the kidneys. In vivo both the liver and the kidneys are able to process some of the EGF-(45 kDa) to EGF-(6 kDa) immunoreactivity.

Role of vasoactive intestinal polypeptide (VIP) and endogenous somatostatin on the secretion of epidermal growth factor (EGF): studies on duodenal tissue cultures

Epidermal Growth Factor (EGF)-containing cells have been found in Brunner's glands in the same area where several regulatory peptides are released. The present study was aimed at testing the release and the regulation of EGF secretion from cultured duodenal biopsies obtained from healthy individuals by gastroscopy. The effects and the interaction of VIP and somatostatin on the hormone release were studied. Duodenal biopsies were cultured at 37 degrees C in Mc Coy's buffer, gassed with 95% O2 and 5% CO2. After 30 min, the culture medium was decanted for the measurement of the hormones by RIA. To measure the protein content, the tissue was then homogenized; EGF detected in the culture was 11.5 ng/mg protein. The addition of VIP in the medium increased EGF mean levels to 21.6 ng/mg protein (P less than 0.01). The biopsies thus obtained were cultured with anti-somatostatin antibodies to evaluate the influence of endogenous somatostatin on EGF secretion. The inclusion of anti-somatostatin antibodies increased the EGF levels to 41.2 ng/mg protein (P less than 0.01). The combined addition of anti-somatostatin antibodies and VIP in the culture caused a mean EGF increase significantly higher than the values obtained separately by VIP and somatostatin (P less than 0.01). In conclusion, we can suggest a triangular interaction model of EGF release, where the somatostatin seems to be the negative monitor of over-secreted VIP and EGF from the gut.

The trophic effect of epidermal growth factor on morphological changes and polyamine metabolism in the small intestine of rats

This study was undertaken to evaluate the effect of epidermal growth factor (EGF) on the morphological changes and polyamine metabolism in the atrophic small intestinal mucosa of rats caused by feeding elemental diet (ED; Elental, Ajinomoto, Tokyo) for several weeks. Four-week-old Wistar male rats were given ad libitum ED (1 kcal/ml) for 4 weeks. The body weight increased to the same extent as the control group fed a pellet diet. However, the small intestine became atrophic: the mucosal wet weight of the jejunum decreased to 70%, while that of the ileum decreased to 60%. EGF (10 micrograms/kg) was subcutaneously injected into these rats every 8 hours. Ornithine decarboxylase (ODC) activities of the jejunal and ileal mucosa rose within 12 hours of the initial EGF administration. Mucosal DNA specific activities tended to increase. Next, EGF (30 micrograms/kg/day) was intraperitoneally administered with a Mini-osmotic pump for one week. The wet weight, protein and DNA contents of the ileal mucosa increased significantly compared with those of the saline administered controls, while the crypt cell production rate (CCPR) also increased. Histologically, increases in both villus height and crypt depth were confirmed. These findings indicate that EGF causes mucosal proliferation through polyamine metabolism even in the atrophic small intestine of mature rats after ED administration for 4 weeks.

Epidermal growth factor prolongs survival time of tumor-bearing mice

We observed that human epidermal growth factor (hEGF) alone prolonged the survival time of mice bearing various murine syngeneic tumors as well as athymic nude mice bearing human xenografts. No changes in the subcutaneous solid tumor mass volume were observed. Prolongation of survival time by hEGF was observed in mice bearing murine epidermoid carcinoma (BSC) and human gastric carcinoma (KATO III), but not in murine epidermoid carcinoma (KLN205) or human epidermoid carcinoma (A431). Human tumor cells such as A431, KATO III, and murine tumor cells, KLN205, BSC had roughly 2 X 10(6), 3 X 10(4), 1.3 X 10(3) and 1 X 10(3) EGF receptors/cell, respectively. Although KLN205 and BSC tumor cells maintained nearly the same number of EGF receptors, the effects of hEGF were very different. Although A431 tumor cells had nearly 100 times more receptors than KATO III cells, the prolongation of survival time of mice bearing A431 by hEGF was no better than that of mice bearing KATO III. Accordingly, it appears that this prolongation of survival time by hEGF is independent of the number of EGF receptors on tumor cells. In addition, hEGF was shown to inhibit experimental pulmonary metastasis of murine BSC tumor, but was ineffective with murine KLN205 tumor. These results suggest that prolongation of survival time by hEGF may result from the inhibition of tumor cell metastasis and EGF may play a role in preventing the metastasis of certain malignant neoplasms unrelated to its effects through the EGF receptor on tumor cells.

Considerations on the role of surface tension and epidermal growth factor in the mechanism of integumental pattern formation

The formation of the posterior parietal hair whorl during normal human development is proposed as a morphogenetic problem in which the effects of surface tension and the appearance of singularities figure prominently. Surface tension is considered in the sense of "Langer's lines" which define local contours of tension in the skin of the organism. According to this view, an analysis of the organism's skin tension field is fundamental to problems of integumental pattern formation. A computational analysis of the skin tension field is proposed, potentially using methods from finite element theory applied to molecular and cellular mechanisms within the skin which resist deformation. To this end, surface tension is provisionally defined as the differential adsorption (adhesion) of molecular and supramolecular binding elements within the skin. In practical applications, it is suggested that epidermal growth factor (EGF) and similar molecules have the physicochemical features and the biological effects required to experimentally probe surface tension phenomena at supramolecular levels. In this regard, the concept of topological discontinuities is introduced as a potential theoretical bridge across levels of organization. Specific examples of these discontinuities are given and discussed in terms of the development of singularities in control surfaces. It is hoped that these considerations will be useful in the mechanistic analysis of hair whorl formation during human embryo-genesis and in other problems of integumental pattern formation and nonequilibrium surface behavior.

Epidermal growth factor (EGF) prevents methylprednisolone-induced inhibition of wound healing

Subcutaneously implanted cylindrical hollow viscose cellulose sponges were used to study the effect of locally applied epidermal growth factor (EGF) on methylprednisolone-induced inhibition of granulation tissue formation in rats. In in vivo studies the sponges were treated immediately after implantation with a single injection of 2 mg (approximately 1.7 x 10(-3) M) of depot methylprednisolone or with its carrier solution only. Thereafter the implants were injected daily with 5 micrograms of EGF or with its carrier solution 0.1% albumin for 7 days. Methylprednisolone treatment decreased the accumulation of nucleic acids, collagen, and glycosaminoglycans in the developing granulation tissue. After daily injections of EGF the concentrations of these tissue components returned close to the control values. In cultures of rat granulation tissue fibroblasts, 10(-4) M and 10(-3)M methylprednisolone decreased collagen synthesis by 41 and 81% from the control level, respectively. In the presence of methylprednisolone EGF treatment could not increase collagen synthesis of fibroblasts. Methylprednisolone treatment resulted in a dose-dependent reduction in pro alpha 1(I) collagen mRNA levels, which was partially inhibited by low EGF concentrations (1 and 10 ng/ml). In the presence of methylprednisolone all concentrations of EGF increased fibronectin mRNA levels in a dose-dependent manner. It is concluded that EGF treatment can prevent the inhibitory effect of methylprednisolone on wound healing by stimulating fibroblast proliferation but does not stimulate collagen synthesis per cell.

Autoradiographic localization of binding sites for epidermal growth factor-urogastrone (EGF-URO) in coronary arteries

Previously published data have indicated that epidermal growth factor-urogastrone (EGF-URO) can regulate blood flow in vivo and can modulate vascular smooth muscle contractility in vitro. However, the exact location of the receptors responsible for this vascular action of EGF-URO has not been previously determined. In this report, employing in vitro autoradiography with 125I-labeled EGF-URO, we have documented the presence of specific EGF-URO binding sites in the tunica media of bovine and porcine coronary arteries. Our observations support the indirect evidence pointing to presence of EGF-URO receptors on the smooth muscle elements of arterial tissue. Our data also support further the hypothesis that EGF-URO and related growth factors (like TGF-alpha or PDGF) may play a role in normal and pathophysiological vascular function.

Effect of orally-administered epidermal growth factor on intestinal iron absorption and mucosal permeability

A progressive increase in intestinal 59Fe3+ absorption was observed on oral feeding of mice with physiological doses of EGF/UGO. Maximal changes were apparent after 3d and appeared to be dose-dependent. In addition to a small increase in intestinal cell proliferation, as reflected by increased ornithine decarboxylase activity, EGF/UGO-feeding increased mucosal permeability (evaluated with [51Cr]-EDTA): the latter could account for the increase in iron absorption. Sialoadenectomy, to remove the major source of endogenous EGF/UGO, had no appreciable effect on the intestinal absorption of iron.

The physiology of wound healing

Many of the biochemical events of wound healing are prisoners of the victim's physiologic state. Although the initial local events of inflammation occur normally in any viable tissue, the subsequent reparative capacities of macrophages, fibroblasts, and endothelial cells are seriously impaired by any compromise of local perfusion and oxygenation. In particular, the bacteriocidal capacities of granulocytes are heavily dependent on local oxygenation/perfusion, nutrition, and endocrine status. This article depicts the local mechanisms of repair with special attention to the means by which physiologic and nutritional support at the clinical level influence repair, even to a point at which wound healing may exceed contemporary expectations. Without appropriate physiologic, nutritional, and endocrine support, wound healing often fails totally. It is now possible, although not always easy, to achieve optimal physiologic support.

Inhibition by anti-inflammatory agents of contraction induced by epidermal growth factor-urogastrone in isolated longitudinal smooth muscle strips from guinea-pig stomach

1. Epidermal growth factor-urogastrone (EGF-URO) caused a concentration-dependent contractile response of longitudinal muscle strips from the gastric body of the guinea-pig stomach. The contractile response to EGF-URO was monophasic, with tension returning rapidly to baseline. Desensitization was evident in that further addition of EGF-URO to the organ bath did not cause a second contraction. 2. Preincubation with indomethacin, ibuprofen, naproxen and aspirin markedly inhibited the contractions induced by EGF-URO with an order of potency (indomethacin greater than naproxen greater than ibuprofen greater than aspirin) that reflected the ability of these agents to inhibit cyclo-oxygenase. 3. The data indicate that prostanoids mediate the action of EGF-URO in the longitudinal muscle preparation. 4. Auranofin (0.5 to 50 microM), a chrysotherapeutic agent with antiproliferative properties used for treating rheumatoid arthritis, also markedly inhibited the EGF-URO response; however, other gold-containing compounds (aurothioglucose or gold sodium thiomalate at 30 to 100 microM) failed to cause significant inhibition. 5. Preincubation of preparations for 2 h with 1 microM hydrocortisone, prednisolone or dexamethasone caused an inhibition of EGF-URO-induced contraction of approximately 50%. However, steroids lacking either a 17 alpha-hydroxyl (corticosterone) or an 11 beta-hydroxyl (cortisone, deoxycorticosterone, prednisone) substituent did not inhibit the contraction caused by EGF-URO. For hydrocortisone, the inhibitory effect was half-maximal at 0.2 microM and was maximal at 1 microM. Cycloheximide (10 microM) blocked the inhibitory action of hydrocortisone and potentiated the contractile action of EGF-URO. 6. The ability of a variety of steroidal and non-steroidal anti-inflammatory agents to interfere with the action of EGF-URO in a smooth muscle preparation suggests that these agents may also inhibit the action of EGF-URO mediated by prostanoids in other target tissues. 7. The data also point to a potential role for EGF-URO in regulating gastric motility.

Urine human epidermal growth factor (hEGF) levels following surgery

In order to investigate the contribution of growth factors in conditions of postoperative stress, we measured the blood and urine hEGF levels in patients with various surgical disorders. While the levels of serum and plasma hEGF did not change significantly after surgery, urine hEGF (u-hEGF) stayed at the base-level followed by a single peak within a postoperative period of two weeks. The peak day of u-hEGF in patients with more than 1000 ml of intraoperative bleeding was later than that in patients with bleeding of less than 1000 ml. In patients with postoperative renal failure or dysfunction, u-hEGF levels dropped and did not rise until the recovery of renal function. The changing pattern of u-hEGF levels was an indicator of operative bleeding volume and renal function.

Distribution of i.v. administered epidermal growth factor in the rat

The distribution of i.v. injected 125I-labeled epidermal growth factor (EGF) was examined in the rat. The uptake of radioactivity was examined for the following tissues: liver, kidney, skin, stomach, small intestine, colon, brain, submandibular gland, lung, spleen, and testis. 125I-EGF was cleared from the circulation within minutes. At 2.5 min after the injection only 7% of the label was left in the blood. Most of the label was found in the liver (52%), the kidneys (14%), the small intestine (11%) and the skin (7%). The other organs examined contained 1% or less of the radioactivity. The uptake of 125I-EGF per g tissue was markedly higher for the liver and kidneys than for the rest of the organs. By autoradiography 125I-EGF was found in the peripheral parts of the classical liver lobule, in the proximal tubules of the kidneys, in the surface epithelium of the stomach, and in the surface epithelium of the villi in the small intestine. In conclusion the present study showed that small doses of homologous EGF was cleared from the circulation of rats within minutes, mainly by the liver, the kidneys, and the small intestine.

Epidermal growth factor receptor in human breast cancers: correlation with estrogen and progesterone receptors

Epidermal growth factor receptor (EGFR), determined by the Scatchard curve method, was found in 22 cases of a random series of 100 patients with breast carcinoma. Two groups of patients were identified, one (n = 16) with a low concentration (0-50 fm/mg protein) of EGFR but with a high affinity (Kd = 3.2 nM), and the other (n = 6) with a high concentration (90-210 fm/mg protein) of EGFR but with a lower affinity (Kd = 6.3 nM). A significant inverse relationship was found between the presence of EGFR and receptors for estrogen (p less than 0.001) and progesterone (p = 0.001). EGFR was found in no (0/8) tumors with Grade I histoprognostic grade, 17% (10/58) Grade II, and 38% (11/29) Grade III (p less than 0.05). EGFR is present therefore in poorly differentiated tumors and associated with other factors of poor prognosis. Our in vivo analyses confirm results found in tissue culture derived from human breast carcinoma cells.

Visualization of growth factor receptor sites in rat forebrain

It is now known that various growth factors may also act in the central nervous system. Among them, it has recently been shown that epidermal growth factor (EGF) and insulin-like growth factor I (IGF-I) may possess trophic effects in the mammalian brain. We report here on the respective autoradiographic distribution of [125I]EGF and [125I]IGF-I receptor binding sites in the rat brain, both during ontogeny and in adulthood. It appears that [125I]EGF sites are mostly found in the rat forebrain during brain development. On the other hand, [125I]IGF-I sites are more widely distributed both during ontogeny and in adulthood. These results reveal the plasticity of the expression of EGF and IGF-I receptor sites in the mammalian brain. This could be relevant for the respective role of these two growth factors in the development and maintenance of neuronal function.

Epidermal growth factor in the normal and neoplastic kidney and bladder

Epidermal growth factor (EGF) is a cell-regulating polypeptide that appears important to the maintenance and function of some benign tissues and to the transformation and proliferation of certain malignancies. In humans the highest concentrations of EGF are found in the urine. We investigated possible interactions between EGF and normal and neoplastic tissues of the urinary system with indirect immunohistochemical staining of paraffin-embedded tissue sections. A polyclonal antibody directed against mouse EGF but shown to react with human EGF was used in the assays. Positive staining was granular in nature and confined to the cytoplasm. Staining of the renal parenchyma (N = 5) was observed in the epithelium of the proximal and distal tubules and the collecting ducts. There was staining of clear cell (N = 6) and papillary (N = 3) carcinomas of the kidney. Staining of the normal urothelium (N = 5) was limited to superficial cells. All transitional cell (N = 21) and squamous (N = 2) carcinomas of the bladder stained. Subjectively, the staining intensity of the transitional cell carcinomas correlated inversely with tumor differentiation. In light of evidence that internalized, receptor-bound EGF is rapidly degraded, the striking immunohistochemical demonstration of cytoplasmic EGF suggests active synthesis. EGF synthesized by urothelial and renal carcinomas may be involved in an autocrine mechanism of malignant proliferation.

Differential response of the human hepatoma-derived cell line HA22T/VGH to polypeptide mitogens

Several human cell lines derived from primary cancer of the liver are able to grow under serum-free conditions and produce spreading and growth factors which are released into the culture medium. Since this autocrine growth under hormone-free conditions might play a basic role in malignant transformation, we studied the effect on cell replication and the presence of specific membrane receptors of epidermal growth factor (EGF) and insulin on a dedifferentiated human hepatoma cell line, named HA22T/VGH. Our results point to a similar inhibitory effect on cell replication in the presence of both EGF and insulin, in spite of detecting different affinities of binding.

Epidermal growth factor-urogastrone causes vasodilatation in the anesthetized dog

Epidermal growth factor-urogastrone (EGF-URO) administered intraarterially was a potent dilator in dog femoral (FEM), superior (cephalic) mesenteric (SMA), celiac (CAC), coronary (COR), carotid (CAR), and renal (REN) vascular beds. The effects of EGF-URO, which exhibited tachyphylaxis, could not be attributed either to recirculating EGF-URO or to the secondary release of other agonists or products of the cyclooxygenase pathway. Two vascular beds (FEM, SMA) showed a high maximum responsiveness to EGF-URO (maximum effect [Emax] approximately equal to 70% increase in flow) whereas another group (CAC, COR, CAR, and REN) exhibited lower responsiveness (Emax approximately equal to 20%). The ED50 for this effect of EGF-URO was in the range of 0.4 micrograms (FEM, SMA, CAR, and COR) to 0.9 micrograms (CAC and REN). In isolated dog COR helical strips, EGF-URO did not exhibit either a direct relaxing or a contractile effect. However, preincubation of strips with EGF-URO caused up to a 66% inhibition of contraction in response to norepinephrine (1 microM), with an ED50 for EGF-URO of 1 nM. This action of EGF-URO also showed marked tachyphylaxis. Our data point to a potential role for EGF-URO (and possibly for the structurally related alpha-transforming growth factor) in the regulation of blood flow in vivo.

Epidermal growth factor (urogastrone)-stimulated gluconeogenesis in isolated mouse hepatocytes

In freshly isolated mouse hepatocytes obtained from fasted animals, we have studied the receptors for epidermal growth factor urogastrone (EGF-URO) in terms of the electrophoretic profile, ligand affinity, and numbers of EGF-URO receptors present on the cells, and also in terms of the ability of EGF-URO to stimulate gluconeogenesis, as reflected by the increased incorporation of [3-14C]pyruvate into glucose. The effects of EGF-URO were compared with those of glucagon. Ligand-binding studies revealed that the mouse hepatocytes possess an unusually high number of EGF-URO receptors (about 3 X 10(6) binding sites/cell), with a ligand dissociation constant of 4.4 nM. The binding of EGF-URO by mouse hepatocytes was more than 10-fold higher than the previously measured binding of EGF-URO by rat hepatocytes. Crosslink-labeling studies, coupled with gel electrophoretic analysis, demonstrated the presence of intact EGF-URO receptors, although some receptor processing had occurred during the isolation procedure. EGF-URO was able to stimulate the incorporation of 3-14C-labeled pyruvate into glucose; glucagon was unable to do so. In contrast, in rat hepatocytes isolated and assayed under identical conditions, glucagon (10 nM) caused a marked (250%) stimulation of the incorporation of pyruvate into glucose. Maximally, EGF-URO caused a 34% increase in the incorporation of [3-14C]pyruvate into glucose; a half-maximal effect was observed at a concentration of 2.5 nM EGF-URO. The stimulatory effect of EGF-URO was not dependent on the concentration of pyruvate, lactate, glucose, or calcium in the incubation medium. Although raising the concentration of pyruvate in the incubation medium increased the incorporation of [3-14C]pyruvate into glycogen, EGF-URO did not cause any change in the incorporation of radioactivity into glycogen. Overall, our data point to marked differences between rat and mouse liver preparations, in terms of the hormonal regulation of glucose metabolism, and our work documents a potential role for the remarkably high number of mouse hepatocyte EGF-URO receptors in terms of the modulation of gluconeogenesis in the mouse.

The effects of epidermal growth factor on neural crest cells in tissue culture

Epidermal growth factor (EGF) stimulates the release of hyaluronic acid (HA) and chondroitin sulfate proteoglycan (CSPG) from quail trunk neural crest cultures in a dose-dependent fashion. It also promotes the expression of cell-associated heparan sulfate proteoglycan (HSPG) as detected by immunofluorescence and immunoprecipitation of the 3H-labeled proteoglycan. Furthermore, EGF stimulates [3H]thymidine incorporation into total cell DNA. These results raise the possibility that EGF or an analogous growth factor is involved in regulation of neural crest cell morphogenesis.

Epidermal growth factor acts as a corticotropin-releasing factor in chronically catheterized fetal lambs

Epidermal growth factor (EGF) has been reported to stimulate adrenocorticotropin hormone (ACTH), growth hormone and prolactin secretion from pituitary tissue in vitro, and in large doses evokes ACTH secretion in adult sheep in vivo. In order to assess a possible role for EGF in the pituitary hyperfunction characteristic of the in utero fetus, we measured changes in plasma immunoreactive ACTH concentrations after acute administration of saline, purified mouse EGF or synthetic ovine corticotropin releasing factor (CRF) to chronically catheterized fetal sheep. Both CRF and EGF were associated with increases in plasma immunoreactive ACTH concentrations. Peak values 60 min after 10-micrograms injections of either EGF or CRF increased from baseline ACTH values of 61 +/- 11 pg/ml to 191 +/- 37 and 178 +/- 25 pg/ml, respectively. Dose-response studies indicate that at low doses (less than 20 micrograms) EGF is as potent a stimulus for ACTH release as CRF. EGF infusion was not associated with detectable changes in circulating CRF, catecholamines, arginine vasopressin levels, or plasma growth hormone concentrations. We speculate that EGF may be important in the regulation of pituitary function in the developing mammalian fetus.

Effect of sialoadenectomy and synthetic human urogastrone on healing of chronic gastric ulcers in rats

The effect of extirpation of the submandibular glands, an exocrine organ for epidermal growth factor/urogastrone (EGF/URO), and the effect of oral administration of synthetic human (EGF/URO) on healing of chronic gastric ulcers in rats has been investigated. Removal of the submandibular glands delayed healing of chronic gastric ulcers when examined after 50, 100, and 200 days. Oral administration of synthetic human EGF/URO stimulated gastric ulcer healing when examined after 25 and 50 days of treatment. The effect of synthetic human EGF/URO was comparable with that of cimetidine. The combined administration of synthetic human EGF/URO and cimetidine further increased healing of gastric ulcers compared with administration of each substance. Neither synthetic human EGF/URO, nor removal of the submandibular glands had any influence on gastric acid secretion. This study showed that the submandibular glands influence healing of chronic gastric ulcers and suggest that EGF/URO participate in healing of chronic gastric ulcers in rats.

Effect of epidermal growth factor (EGF) on experimental granulation tissue

Subcutaneously implanted cylindrical hollow viscose cellulose sponges were used to study the effects of locally applied epidermal growth factor (EGF) on developing granulation tissue in rats. In the first set of experiments the test implants were treated with a single injection of a solution containing 5 micrograms of EGF in 0.5% albumin while the control implants were treated correspondingly with the carrier solution only. In the second set of experiments the injections of both test and control implants were repeated daily. Analyses of wound fluid and granulation tissue in the sponge cylinders were carried out 10 days after implantation. After single application of EGF no essential differences were detected in wound fluid prostaglandin E2 levels or various components of granulation tissue between the groups. After daily application, however, a stimulatory effect of EGF on granulation tissue formation was observed: cellularity increased, as evidenced by the elevated amounts of nucleic acids, and accumulation of collagen and glycosaminoglycans was enhanced.

Vasoactive intestinal polypeptide and acetylcholine stimulate exocrine secretion of epidermal growth factor from the rat submandibular gland

The effect of vasoactive intestinal polypeptide (VIP) and acetylcholine on secretion of epidermal growth factor (EGF) from the rat salivary glands was investigated. VIP in doses of 3 X 10(-10) to 3 X 10(-8) mol/kg per h stimulated secretion of saliva and total output of EGF dose-dependently. Acetylcholine also stimulated salivation and output of EGF. VIP in a dose of 3 X 10(-11) to 3 X 10(-10) mol/kg per h enhanced the stimulatory effect of acetylcholine, but this effect disappeared when the dose of VIP was increased. Adrenalectomy decreased acetylcholine stimulated total output of EGF by approximately 50%, but only by 20% when acetylcholine plus VIP was administered. EGF was localized to the convoluted granular tubules in the submandibular gland, whereas EGF could not be detected in the remaining salivary glands. The results suggest that VIP and acetylcholine cooperate in the control of exocrine secretion from the rat salivary glands. The effect of acetylcholine, however, seems to be partly dependent on circulating catecholamines.

Mechanisms of receptor-mediated transmembrane signalling

Although this paper has dealt with general mechanisms whereby a hormonal signal is transmitted across the cell membrane, advances in work with a number of receptors should permit a precision of description of these mechanisms that would have delighted both Langley and Ehrlich. For instance, the detailed sequences now known for the separate subunits of the nicotinic cholinergic receptor and the cellular manipulations made possible by the cloning of the separate subunit genes will make it possible to determine the precise receptor sequence involved either in acetylcholine binding or in ion channel function. The complete sequences and biochemical properties now known for the insulin and EGF-URO receptors to be dealt with in part by a subsequent article (van Obberghen and Gammeltoft, this series) should lay the groundwork for elucidating the transmembrane signalling mechanisms used by the kinase family of growth factor receptors. Continuing work on the structure of the beta-adrenergic receptor, and on the interaction of such receptors with guanine nucleotide regulatory complexes and on the detailed properties of the family of so-called G-proteins and their associated regulatory subunits should unravel the details for a variety of transmembrane signalling reactions. Thus, at least for three basic transmembrane signalling mechanisms: ligand modulated ion transport; ligand-modulated receptor enzyme activity (e.g. tyrosine kinase); and ligand-modulated liberation of cryptic mediators (like the alpha- and beta-subunits of the guanine nucleotide regulatory complexes) one can look forward with excitement to the elucidation in the not-too-distant future of a number of specific biochemical reaction pathways that lead to cell activation.

Human breast cancer cells synthesize and secrete an EGF-like immunoreactive factor in culture

A human breast cancer cell line, strain MCF-7, in culture synthesized and secreted a large amount of a polypeptide (designated as MCF-7 EGF) immunologically related to human epidermal growth factor (hEGF). The molecular weight of MCF-7 EGF estimated by gel filtration on Sephadex G-75 was similar to that of hEGF from human urine. On isoelectric focusing analysis, MCF-7 EGF gave a major peak at pH 4.6 and a minor peak at pH 5.0. In our enzyme immunoassay system, however, the dose-response curve of MCF-7 EGF did not show good parallelism with that of standard hEGF. From these results, it is suggested that MCF-7 cells synthesize and secrete a polypeptide immunologically related to hEGF into the culture medium.

Oral administration of synthetic human urogastrone promotes healing of chronic duodenal ulcers in rats

The effect of oral administration of synthetic human epidermal growth factor/urogastrone (EGF/URO) on healing of chronic duodenal ulcers induced by cysteamine in rats was investigated and compared with that of cimetidine, a H2-receptor antagonist. After 25 and 50 days of treatment, synthetic human EGF/URO significantly increased healing of chronic duodenal ulcers to the same extent as cimetidine. Combined treatment with synthetic human EGF/URO and cimetidine for 25 days was more effective than synthetic human EGF/URO given alone, whereas combined treatment for 50 days was significantly more effective than cimetidine alone. These results show that a combination of an agent inhibiting gastric acid secretion and the cytoprotective and growth-stimulating peptide EGF/URO seems to be more effective with regard to duodenal ulcer healing than individual administration of the two substances. Synthetic human EGF/URO is a potent inhibitor of gastric acid secretion when administered intravenously, but had no effect on acid secretion when given intraduodenally, which suggests that the effect of synthetic human EGF/URO is a direct action on the duodenal mucosa. In conclusion, this study showed that oral synthetic human EGF/URO has a significant effect on healing of duodenal ulcers in rats. The amount of synthetic human EGF/URO administered is comparable to that found in saliva during stimulation of the salivary glands. Our results, therefore, suggest that EGF/URO is one of the endogenous factors participating in healing of duodenal ulcers.