Do HPA and PHA-L have the same binding pattern in metastasizing human breast and colon cancers?

Glycoconjugates on the tumour cell surface are functionally important for the interaction of the tumour cell with its environment. Several studies have demonstrated that particular carbohydrate residues on primary cancers are associated with metastasis. Identification of such residues is possible using lectins, including Helix pomatia agglutinin (HPA) which has a nominal monosaccharide specificity for N-acetyl galactosamine (GalNAc) and Phaseolus vulgaris leucoagglutinin (PHA-L) which recognizes beta1-6 branched oligosaccharides. Both lectins have been reported to be valuable prognostic markers in breast and colon cancers. In the present study, the binding patterns of both lectins were investigated on serial sections of human breast cancers and on metastatic and non-metastatic human breast and colon cancer cell lines grown in severe combined immunodeficient (SCID) mice. The two lectins gave very different staining patterns and HPA was more often associated with metastases than PHA-L. Our results indicate that both lectins are not simply recognizing different oligosaccharides associated with the same common metastasis-related glycoconjugate.