Inhibition of tumor growth by plasminogen-related protein-B

Background: Various fragments of the fibrinolytic protein plasminogen can a ct as antiangiogenic factors and inhibit the growth of primary and metastat ic tumors in mice. Plasminogen-related gene-B encodes a putative 9 kDa prot ein virtually identical to the plasminogen N-terminal activation peptide, a 77-amino acid motif that is liberated from the parent plasminogen molecule during conversion to the serine proteinase plasmin. Previous data have doc umented enhanced transcription of plasminogen-related gene-B in neoplastic tissues. Materials and Methods: We have tested the effects of recombinant v ersions of plasminogen-related protein-B and the plasminogen N-terminal act ivation peptide on the growth of tumors in mice, employing murine tumor cel l lines implanted subcutaneously. Results: The recombinant plasminogen-rela ted protein-B significantly inhibited the growth of primary tumors in mice, while recombinant plasminogen N-terminal activation peptide elicited only a slight inhibition of tumor growth. Conclusion: These data suggest that pl asminogen-related protein-B may have utility as a novel cancer therapeutic.