DANSYLATED OCTAPEPTIDE DNS-GLU-ASP-ASP-SER-ASP-GLU-GLU-ASN INHIBITS THE PROLIFERATION RATE OF HL-60 CELLS

Small acidic phosphorylated chromatin peptides show regulatory activit y on gene expression. The peptide pyroGlu-Asp-Asp-Ser-Asp-Glu-Glu-Asn, synthesized on the basis of structural and biochemical studies, shows functional properties in vitro (phosphorylation by casein kinase II, control of DNA transcription by RNA polymerase II, inhibition of proli feration and promotion of differentiation in some cell lines) very sim ilar to those of native chromatin peptides. In this report we show tha t the dansylated octapeptide Dns-Glu-Asp-Asp-Ser-Asp-Glu-Glu-Asn remar kably inhibits cell growth of the HL-60 cell line. The biological effe ct of the peptide seems to be considerably higher than that shown by t he nondansylated peptide, and it cannot be attributed to a toxic effec t of the Dns group. The measurement of uptake of H-3-labelled Glu-Asp- Asp-Ser-Asp-Glu-Glu-Asn demonstrates that it is unable to pass through the HL-60 cell membrane. It is our considered opinion that the additi on of hydrophobic groups to the peptide N-terminus should increase the biological activity by improving its transport through the cellular m embrane.