Effect of luminal epidermal growth factor on enterocyte glucose and proline transport

1996 ◽  
Vol 271 (3) ◽  
pp. G509-G515 ◽  
Author(s):  
J. A. Hardin ◽  
J. K. Wong ◽  
C. I. Cheeseman ◽  
D. G. Gall
Keyword(s):  
Growth Factor ◽  
Epidermal Growth Factor ◽  
Tyrosine Kinase ◽  
Glucose Transport ◽  
Brush Border ◽  
Brush Border Membrane ◽  
Basolateral Membrane ◽  
Channel Blockade ◽  
Na Permeability ◽  
Epidermal Growth

The effect of luminal epidermal growth factor (EGF; 60 ng/ml) and tyrphostin-51 (TYR; 10 microM), a tyrosine kinase inhibitor, on rabbit jejunal brush-border and basolateral membrane transport was investigated. In separate experiments, the effect of EGF, EGF and TYR, or TYR alone was examined in in vivo loops. In addition, Na+ permeability in brush-border membrane vesicles (BBMV) and the effect of Ca2+ channel blockade on EGF-stimulated glucose uptake were examined. Luminal EGF significantly (P < 0.0001) increased the maximal rate of transport (Vmax) for glucose and proline uptake in BBMV. TYR and Ca2+ channel blockade completely abolished the EGF-induced increase in glucose transport and in the case of TYR resulted in a significant reduction in Vmax compared with controls (P < 0.0001). The Michaelis-Menten constant did not differ in any experimental group. EGF had no effect on brush-border Na+ permeability or basolateral membrane glucose transport. The findings indicate a role for EGF in the acute regulation of jejunal brush-border membrane nutrient uptake. Furthermore, tyrosine kinase activity appears to be involved both in mediating EGF-induced alterations in transport function and in the maintenance of basal brush-border membrane function.

Epidermal growth factor upregulates intestinal electrolyte and nutrient transport

1991 ◽  
Vol 260 (6) ◽  
pp. G807-G814 ◽  
Author(s):  
K. Opleta-Madsen ◽  
J. Hardin ◽  
D. G. Gall
Keyword(s):  
Growth Factor ◽  
Epidermal Growth Factor ◽  
Brush Border ◽  
Brush Border Membrane ◽  
Intestinal Transport ◽  
Membrane Vesicles ◽  
Ussing Chambers ◽  
Epidermal Growth ◽  
Net Fluxes

The role of epidermal growth factor (EGF) in the acute regulation of intestinal transport of electrolytes and glucose was examined. In vivo transport studies were performed in New Zealand White rabbits (500–900 g) using a single-pass perfusion technique. In vitro net fluxes were determined under short-circuited conditions in Ussing chambers. Kinetic parameters of glucose transport in the presence and absence of EGF were measured in brush-border membrane vesicles. In vivo studies showed that the addition of 60 ng/ml EGF to the perfusate resulted in increased absorption of H2O, Na+, Cl-, and glucose from the jejunum. In Ussing chambers, the presence of EGF caused an increase in jejunal net fluxes of glucose-stimulated Na+ and 3–O-methylglucose due to an increase in mucosal-to-serosal movements. Verapamil abolished the EGF effect. In the absence of glucose, net fluxes of Na+ and Cl- were enhanced in the presence of EGF due to a decrease in the serosal-to-mucosal movement of both ions. Verapamil had no effect on this decrease. The incubation of EGF with brush-border membrane vesicles had no effect on either the maximal flux or the Michaelis constant of glucose transport. These results indicate that EGF is capable of regulating absorption of electrolytes and nutrients from the small intestine and suggest a role for this peptide in the control of intestinal transport.

The effect of epidermal growth factor on the distribution of SGLT-1 in rabbit jejunum

2002 ◽  
Vol 80 (9) ◽  
pp. 872-878 ◽  
Author(s):  
B M Chung ◽  
L E Wallace ◽  
J A Hardin ◽  
D G Gall
Keyword(s):  
Growth Factor ◽  
Epidermal Growth Factor ◽  
Brush Border ◽  
Brush Border Membrane ◽  
Membrane Vesicles ◽  
Sugar Transporter ◽  
New Zealand White Rabbits ◽  
Rabbit Jejunum ◽  
Microsomal Membranes ◽  
Epidermal Growth

The effect of epidermal growth factor (EGF) on the cellular and villous distribution of the sugar transporter SGLT-1 was examined. New Zealand White rabbits (1 kg) were anesthetized, and two jejunal blind loops were isolated and exposed to either 0.9% saline or EGF (60 ng/mL saline), for 1 h. In separate experiments, tissue was harvested for brush border membrane vesicles (BBMV), microsomal membranes, or fixed for immunohistochemistry. SGLT-1 was measured in membrane fractions by Western immunoblot or localized along the villus–crypt axis by immunofluorescent microscopy. EGF increased BBMV SGLT-1 content compared with paired controls. EGF stimulation also induced a corresponding decrease in microsomal SGLT-1 levels and induced the expression of additional SGLT-1 immunoreactivity further down the villus axis. The findings suggest that EGF upregulates intestinal glucose transport by stimulating the translocation of SGLT-1 from an internal microsomal pool into the brush border, thereby recruiting more villus enterocytes into the glucose transporting population.Key words: EGF, epidermal growth factor, SGLT-1, immunofluorescence.

Recent Advances on Epidermal Growth Factor Receptor as a Molecular Target for Breast Cancer Therapeutics

2020 ◽  
Vol 21 ◽  
Author(s):  
Swathi R. Shetty ◽  
Ragini Yeeravalli ◽  
Tanya Bera ◽  
Amitava Das
Keyword(s):  
Breast Cancer ◽  
Epidermal Growth Factor Receptor ◽  
Growth Factor ◽  
Epidermal Growth Factor ◽  
Tyrosine Kinase ◽  
Critical Role ◽  
Growth Factor Receptor ◽  
Type I ◽  
Egfr Inhibition ◽  
Epidermal Growth

: Epidermal growth factor receptor (EGFR), a type-I transmembrane protein with intrinsic tyrosine kinase activity is activated by peptide growth factors such as EGF, epigen, amphiregulin, etc. EGFR plays a vital role in regulating cell growth, migration, and differentiation in various tissue-specific cancers. It has been reported to be overexpressed in lung, head, and neck, colon, brain, pancreatic, and breast cancer that trigger tumor progression and drug resistance. EGFR overexpression alters the signaling pathway and induces cell division, invasion, and cell survival. Our prior studies demonstrated that EGFR inhibition modulates chemosensitivity in breast cancer stem cells thereby serving as a potential drug target for breast cancer mitigation. Tyrosine kinase inhibitors (Lapatinib, Neratinib) and monoclonal antibodies (Trastuzumab) targeting EGFR have been developed and approved by the US FDA for clinical use against breast cancer. This review highlights the critical role of EGFR in breast cancer progression and enumerates the various approaches being undertaken to inhibit aggressive breast cancers by suppressing the downstream pathways. Further, the mechanisms of action of potential molecules at various stages of drug development as well as clinically approved drugs for breast cancer treatment are illustrated.

scholarly journals HER2-positive breast cancer and tyrosine kinase inhibitors: the time is now

2021 ◽  
Vol 7 (1) ◽  
Author(s):  
Ilana Schlam ◽  
Sandra M. Swain
Keyword(s):  
Breast Cancer ◽  
Epidermal Growth Factor Receptor ◽  
Growth Factor ◽  
Epidermal Growth Factor ◽  
Tyrosine Kinase ◽  
Kinase Inhibitors ◽  
Growth Factor Receptor ◽  
Her2 Positive ◽  
Epidermal Growth ◽  
Positive Breast Cancer

AbstractHuman epidermal growth factor receptor 2 (HER2) positive breast cancer accounts for 20–25% of all breast cancers. Multiple HER2-targeted therapies have been developed over the last few years, including the tyrosine kinase inhibitors (TKI) lapatinib, neratinib, tucatinib, and pyrotinib. These drugs target HER2 and other receptors of the epidermal growth factor receptor family, therefore each has unique efficacy and adverse event profile. HER2-directed TKIs have been studied in the early stage and advanced settings and have shown promising responses. There is increasing interest in utilizing these drugs in combination with chemotherapy and /or other HER2-directed agents in patients with central nervous system involvement, TKIs have shown to be effective in this setting for which treatment options have been previously limited and the prognosis remains poor. The aim of this review is to summarize currently approved TKIs for HER2+ breast, key clinical trials, and their use in current clinical practice.

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