ABERRANT ALPHA-1-]2FUCOSYLTRANSFERASES FOUND IN HUMAN COLORECTAL-CARCINOMA INVOLVED IN THE ACCUMULATION OF LE(B) AND Y-ANTIGENS IN COLORECTA L TUMORS

Evidence indicates that the presence of aberrant alpha --> 2fucosylation pathways is responsible for the accumulation of large quantities of Le(b) and Y antigens in human colorectal carcinoma. Significantly higher activities of alpha1 --> 2 as well as alpha1 --> 3 and alpha1 --> 4fucosyltransferases were found in most of the tissues from carcinoma than in the adjacent normal tissues and in healthy subjects. Alpha1 --> 2Fucosyltransferases associated with the synthesis of Le(b) (Fucalpha1 --> 2Galbeta1 -->3[Fucalpha1 --> 4]GlcNAcbeta) and Y (Fucalpha1 --> 2Galbeta1 -->4[Fucalpha1 --> 3]GlcNAcbeta) structures from Le(a) (Galbeta1 --> 3[Fucalpha1 --> 4]GlcNAcbeta) and X (Galbeta1 --> 4[Fucalpha1 --> 3]GlcNAcbeta) ones, respectively, were demonstrated in colorectal carcinomas and in colorectal carcinoma cell lines (COLO201, LS174T and SW1116). The activation of alpha1 --> 2fucosyltransferase with such new substrate specificities in colorectal carcinoma might result in the preferential synthesis of Le(b) and Y structures from Le(a) and X rather than from H type 1 and H type 2 structures.