Involvement of polyamines in epidermal growth factor (EGF), transforming growth factor (TGF)-α and -β1 action on culture of L6 and fetal bovine myoblasts

Abstract 1. 1. α-Difluoromethylornithine, an irreversible inhibitor of ornithine decarboxylase significantly abolished stimulation of protein synthesis evoked by EGF, TGF-α or -β 1 in L6 and fetal bovine myoblasts. 2. 2. The participation of polyamines in early events evoked by growth factors was shown by a significant stimulation of ornithine decarboxylase and S denosylmethionine decarboxylase activity as well as increased concentration of spermidine and spermine in L6 cells exposed to TGF-α and EGF. 3. 3. TGF-β 1 at a high concentration (1 ng/ml) increased protein synthesis in L6 myoblasts but inhibited it in fetal bovine myoblasts. Metabolic effects of TGF-β 1 in L6 cells was associated with an enhancement of decarboxylase activities, however there were no significant changes in cellular polyamine concentrations. Presented data suggest that polyamines are involved in the signal transduction pathway of EGF, TGF-α, and -β 1 in L6 and fetal bovine myoblasts.