A novel
peptide technology to produce mimicking
peptides of
carbohydrate moiety (which we propose to name glyco-replica
peptides) is a useful tool to elucidate the functions of
glycoconjugate.
Carbohydrate moiety of
ganglioside GD1alpha functions as a molecule involved in the adhesion between murine highly metastatic
lymphoma RAW117-H10 cells and hepatic sinusoidal endothelial (HSE) cells. To prepare
peptides which mimic the
carbohydrate structure of
GD1alpha, phage clones expressing
peptides which bound to a
monoclonal antibody against
GD1alpha (KA17) were isolated from a phage-displayed
random peptide library. Four phage clones having affinity to the
monoclonal antibody KA17 were isolated, and these clones showed inhibitory effect on the binding of KA17 to
GD1alpha. The amino acid sequences of the displayed pentadecamers were determined, and one of the phages displaying sequence WHWRHRIPLQLAAGR bound to HSE cells directly and showed the highest inhibitory effect on the adhesion between RAW117-H10 cells and HSE cells. The synthesized
peptides having the same sequences to the displayed 15mers in the four isolated phage clones also showed the inhibitory effect on the adhesion of RAW117-H10 cells to HSE cells, and, again, the WHWRHRIPLQLAAGR
peptide showed the highest inhibitory effect. Furthermore,
intravenous injection of the
peptide brought almost complete inhibition of the
metastasis of RAW117-H10 cells to lung and spleen, and about 50% inhibition of the liver
metastasis. These results indicate that
GD1alpha plays an important role for
metastasis of RAW117-H10 cells, and the
peptides obtained by the present procedure are able to mimic the functional role of the
glycoconjugate.