Bioactive synthetic peptide of NDF/heregulin.

A folded synthetic peptide analog of NDF (NDF5), which has the 52 amino acid EGF-like domain of NDF alpha 2, has been characterized. The folded peptide stimulates tyrosine phosphorylation of Her2, Her3 and Her4 in breast cancer cells and competes with low affinity with full-length NDF alpha 2 for binding to the cells, while the linear one does not. NDF5 also induces morphologic changes in breast cancer cells. After several days treatment with NDF5 or NDF alpha 2, Her2-transfected MCF7 cells (Her2/MCF7) became similar morphologically to non-transfected MCF7. The biological activity of NDF5 is between 1/10 and 1/100 that of NDF alpha 2. This suggests that other motifs, such as the Ig and spacer domains may be important elements in conferring full activity.