Potency and stability of C terminal truncated human epidermal growth factor

Introduction-Epidermal growth factor (EGF) is normally present as EGF(1-53) . A variety of C terminal truncated forms have been used in preliminary tri als for treating gastrointestinal injury but their relative potency and sta bility when used in a clinical setting are unclear. Therefore, we compared the biological activity of recombinant EGF(1-53), EGF(1-52), EGF(1-51), and the C terminal peptides EGF(44-53) and EGF(49-53). Methods-Purity of farms was confirmed by mass spectrometry. Bioactivity of the different EGF forms was determined using [methyl-H-3] thymidine incorpo ration into primary rat hepatocytes and their ability to reduce indomethaci n (20 mg/kg subcutaneously)/restraint induced gastric injury in rats. Stabi lity of EGF peptides was determined by serial sampling from a syringe drive r system containing EGF/4% albumin in saline. Results-Biological activity assays of EGF(1-53), EGF(1-52), and EGF(1-51) g ave almost identical thymidine uptake dose-response curves (maximal respons es increasing baseline uptake from 4400 (600) cpm (mean (SEM)) to about 22 000 (2000) cpm when EGF was added at 1.6 nM). EGF(44-53) and EGF(49-53) did not stimulate H-3 thymidine uptake. Control rats had 47 (4) mm(2) damage/s tomach, EGF(1-51), EGF(1-52), and EGF(1-53) at 0.16 and 0.80 nmol/kg/h each reduced gastric injury by about 50% and 80%, respectively (both doses p<0. 01 compared with control but no significant difference between the differen t forms). EGF was stable at room temperature for seven days but biological activity decreased by 35% and 40% at two and three weeks, respectively (bot h p<0.01). Exposure to light did not affect bioactivity. Conclusion-EGF(1-51) and EGF(1-52) are as biologically active as full lengt h EGF(1-53) but the C terminal penta- and decapeptides are ineffective. Cli nical trials of EGF can probably use infusion systems for at least 48 hours at room temperature and with exposure to light, without reducing biologica l efficacy.