epidermal-growth-factor and ubenimex

We investigated the effects of microbial protease inhibitors, in particular the aminopeptidase inhibitor bestatin, on DNA synthesis and cell division induced by epidermal growth factor (EGF) in hepatocytes. Although bestatin did not significantly affect binding of EGF to hepatocytes, it inhibited EGF-induced DNA synthesis and cell division. DNA synthesis in rat hepatocytes was maximal 24-26 h after EGF addition to the medium. The time required for maximal DNA synthesis was not affected if bestatin was removed less than 12 h after addition, but synthesis was partially inhibited if bestatin was added to the medium several hours after EGF addition, depending on the time of bestatin addition. Our results suggest that bestatin arrests the new cell cycle induced by EGF at about 12 h after the initiation. Considering also our results obtained by employing other protease inhibitors, we concluded that specific proteases play important roles in hepatocyte DNA synthesis and cell division induced by EGF.

Topics: Aminopeptidases; Animals; Cell Division; Cells, Cultured; DNA; DNA Replication; Epidermal Growth Factor; ErbB Receptors; Kinetics; Leucine; Liver; Male; Phosphorylation; Protease Inhibitors; Protein-Tyrosine Kinases; Rats; Rats, Inbred Strains; Thymidine

Bestatin, a microbial aminopeptidase inhibitor, inhibited insulin- or epidermal growth factor-induced DNA synthesis and cell proliferation in primary cultured hepatocytes of rats. The aminopeptidase inhibitor also affected the growth of FM3A or LOBN cells of mice, when it is included in the culture media at the concentration of 0.5 mg/ml. These results suggest the important role of the bestatin-sensitive aminopeptidase(s) in the process of DNA synthesis and proliferation of animal cells.

Topics: Aminopeptidases; Animals; Cell Division; Cells, Cultured; DNA; Epidermal Growth Factor; Insulin; Leucine; Liver; Male; Phosphorylation; Rats; Rats, Inbred Strains