A peptide with three hyaluronan binding motifs inhibits tumor growth and induces apoptosis.

A number of hyaluronan (HA) binding proteins such as soluble CD44, receptor for hyaluronan-mediated motility (RHAMM), and metastatin inhibit tumor growth and metastasis. To determine whether the HA binding motif is the element responsible for the antitumor effect of this family of proteins, we examined the biological activity of a 42-amino acid peptide (designated as BH-P) that contains three HA binding motifs [B(X(7))B] from human brain HA binding protein. In initial experiments with cultured cells, we found that synthetic BH-P inhibited the proliferation and colony formation of tumor cells. It also blocked the growth of tumors on the chorioallantoic membranes of 10-day chicken embryos. In addition, MDA-435 melanoma cells that had been transfected with an expression vector for BH-P grew at a slower rate in nude mice than the vector-alone transfectants. Final studies revealed that the BH-P could activate caspase-8, caspase-3, and poly(ADP-ribose) polymerase and trigger the apoptosis of tumor cells. Taken together, these results suggest that the HA binding motif that is present in HA binding proteins may be responsible for the antitumor effect exerted by the members of this family.