EXPRESSION OF ALPHA-(1,3)-FUCOSYLTRANSFERASES WHICH SYNTHESIZE SIALYLLE(X) AND SIALYL LE(A), THE CARBOHYDRATE LIGANDS FOR E-SELECTIN AND P-SELECTIN, IN HUMAN-MALIGNANT CELL-LINES

Transcripts of alpha-(1,3)-fucosyltransferases in human epithelial can cer and leukemia cell lines were analyzed by Northern blotting and rev erse transcriptase mediated-polymerase chain reaction using specific p robes and primers which can discriminate between the transcripts deriv ed from the four alpha-(1,3)-fucosyltransferase genes Fuc-TIII, IV, V, and VI. Flow cytometric analysis of the sialyl Le(x) and sialyl Le(a) antigens was also performed on the same cell lines. The sialyl Le(x) antigen was expressed on 14 of 15 epithelial cancer cell lines, and th e sialyl Le(a) antigen was detected on 8 of them. The message of Fuc-T III was detected in most of the epithelial cancer cell lines (14 of 15 ), which correlated with the surface expression of these carbohydrate determinants. In addition, the messages of Fuc-TIV and Fuc-TVI were de tected in most epithelial cancer cell lines, while the message of Fuc- TV was undetectable in most of them. On the other hand, all leukemia c ell lines were positively stained for sialyl Le(x), but none of them w as stained for sialyl Le(a) in flow cytometry. The messages of Fuc-TIV were detected in all leukemia cell lines tested. Small quantities of Fuc-TIII, V, and/or VI messages were also detected in some leukemia ce ll lines in reverse transcriptase mediated-polymerase chain reaction a nalysis. These studies indicate that alpha(1,3)-fucosyltransferase act ivities in epithelial cancer and leukemia cell lines are mixtures of m ultiple molecular species of alpha-(1,3)-fucosyltransferases. It is na tural that epithelial cancer cells contain a significant amount of Fuc -TIII mRNA and leukemia cell lines contain Fuc-TIV mRNA, since their n ormal counterparts, normal epithelial cells and leukocytes, respective ly, are known to contain these fucosyltransferases. The unexpectedly f requent occurrence of Fuc-TIV mRNA in epithelial cancer cell lines may be related to their retro-differentiation associated with tumorigenes is. Another unexpected finding was a weak but significant expression o f the alpha-(1,3)-fucosyltransferases Fuc-TIII, V, and/or VI in leukem ia cell lines detected by reverse transcriptase mediated-polymerase ch ain reaction analysis. Since these enzymes are known to be capable of synthesizing the sialyl Le(x) determinant, this finding implies a poss ibility that some of them may be involved in the synthesis of sialyl L e(x) in leukemia cells.