Stimulation of Nb2 mitogenesis by an analogue of human growth hormone (110-127)

Two 18-mer peptides were synthesized. Peptide E117 had the same amino acid sequence as that in the region 110-127 of human growth hormone [hGH (110-127)]. In the second peptide (L117), E117 was replaced with leucine. Biological activity of the peptides was assessed in cultured Nb2 lymphoma cells. L117 stimulated cell division and DNA synthesis in a concentration-dependent manner. Maximum stimulation was equivalent to that noted with native hGH although L117 was much less potent (L117; EC50 approximately 1 microM vs. hGH; EC50 approximately 20 pM). No demonstrable activity was found with peptide E117. These results suggest that the amphipathic helical structure of hGH (110-127) is crucial for biological activity.