Loss of Wnt-5a protein expression in breast carcinoma patients is associated with a shorter recurrence-free survival as well as increased motility in mammary cell lines. Based on sequence analysis of Wnt-5a 13 peptide fragments were identified and investigated for their ability to mimic the effects of the Wnt-5a protein on mammary cell adhesion and motility. Two of these peptides significantly increased adhesion and impaired the motility of non-tumourigenic breast cancer cell lines, both low in endogenous Wnt-5a protein expression. To identify the shortest possible peptide that still had an anti-motile effect, sequential deletions of two amino acids from the N-terminal side of the shorter of these two peptides were performed. The effect on tumour cell adhesion was gradually lost, and when only 6 amino acids remained the effect was not detectable. However, formylation of the N-terminal methionine of this hexapeptide restored its effect on adhesion and reduced tumour cell motility. The novel formyl-Met-Asp-Gly-Cys-Glu-Leu peptide ligand can serve as a lead substance for anti-metastatic treatment in the «50% of human breast cancers where the endogenous expression of Wnt-5a is reduced.La perte de lexpression de la protéine Wnt-5a chez des patientes atteints dun carcinome mammaire est associée à une survie exempte de récurrence plus courte ainsi quà une motilité accrue dans les lignées cellulaires mammaires. Sur la base dune analyse de séquence Wnt-5a, 13 fragments peptidiques ont été identifiés et analysés en vue dune détermination de leur capacité à reproduire les effets de la protéine Wnt-5a sur ladhésion et la motilité des cellules mammaires. Deux de ces peptides ont considérablement augmenté ladhésion et réduit la motilité de lignées de cellules cancéreuses du sein non tumorigènes, dans les deux cas avec une faible expression de la protéine Wnt-5a. Pour identifier le peptide le plus court possible possédant encore un effet anti-motilité, on a réalisé les délétions s
