INTENDED USE

This Human EGF ELISA kit is to be used for the in vitro quantitative determination of human epidermal growth factor (EGF) concentrations in serum, plasma, cell culture supernatant, urine, and other biological fluids. This kit is intended FOR LABORATORY RESEARCH USE ONLY and is not for use in diagnostic or therapeutic procedures.

INTRODUCTION

Epidermal growth factor (EGF), a polypeptide mitogen, was first observed in 1959 by Cohen and Levi-Montalcini while studying Nerve Growth Factor (NGF) in snake venom extracts.¹ It was subsequently isolated and purified from mouse submandibular glands. When injected into new-born mice this new factor caused precocious eyelid opening and incisor eruption.^2,3 EGF was further purified, based on its ability to induce the proliferation of basal skin cells.⁴ Also, a potent inhibitor of gastric acid secretion was identified and isolated from the urine of a pregnant women, and named human ß‑urogastrone. It was shown that this protein was very similar to purified human EGF.^5,6

The cDNA cloning of mature EGF revealed that this polypeptide (6 kDa, 53 amino acids)belonged to a family of growth factors (TGF-a, vaccinia virus growth factor and amphiregulin) that bind to the same 160-185 kDa family of cell surface receptors. Structurally EGF is homologous to TGF-α.^7,8,9 Mature EGF is formed when the large precursor molecule (pre-EGF), a transmembrane protein (130 kDa, 1217 amino acids) which contains at least seven EGF-like sequences is cleaved. Within this precursor molecule, it is the sequence closest to the C-terminus of the mRNA that represents the coding region for the mature, soluble EGF sequence.^7,10 The uncleaved precursor shows biological activity and is capable of binding to the EGF receptor.^11,12 The physiological significance of the EGF precursor, nor the mechanisms of its processing into mature EGF have yet to be illustrated. However it is a source for soluble EGF and may be involved in cell to cell signalling or “juxacrine” action by negotiating intercellular communication between membrane-anchored EGF and cells with EGF receptors on their surfaces.^7,11 A soluble form of the EGF precursor molecule has been shown to be a heparin-binding protein, upon cleavage and release of the precursor extracellular domain.¹²

EGF is found in a variety of bodily fluids and tissues, but lower amounts are generally found in the latter. Substantial quantities of EGF are seen in saliva, bile, pancreatic juice, amniotic fluid, mammary fluids and secretions, gastric and duodenal contents, prostatic and seminal fluids, and urine.^7,11 Lower amounts of EGF can be found in whole blood and platelet poor plasma, when compared to other body fluids. EGF may be released from platelets during blood coagulation, since EGF levels are increased in serum, when compared to plasma.¹³ EGF stimulates the growth of many tissues³ and contributes to a wide variety of in vitro and in vivo biological effects, which are varied and depend on the target tissue. In vivo, EGF promotes angiogenesis, liver regeneration, epithelial development, acceleration of wound healing, and inhibits gastric acid secretion.⁹ It has been shown that EGF in vitro promotes colony formation of epithelial cells in culture,¹⁴ suppress insulin-induced glucokinase (hexokinase IV) activity,¹⁵ promotes chemomigration of prostate tumor cell line⁽¹⁶⁾ and is a mitogen for fibroblasts and endothelial cells.^17-18 Thus, EGF may play a role in human health and disease and could have potential therapeutic role in wound healing, regeneration of liver tissue and repair, embryonic and infant development, and prevention of vaccinia virus infection.⁹

This EGF ELISA is a 2.5 hour solid phase immunoassay readily applicable to measure EGF levels in serum, plasma, cell culture supernatant, urine, and other biological fluids in the range of 0 to 1000 pg/mL. It showed no cross reactivity with other cytokines tested. This assay recognizes natural human EGF, recombinant EGF, and high molecular weight forms of EGF in human urine. This EGF ELISA is expected to be effectively used for further investigations into the relationship between EGF and the various conditions mentioned.