Structures of N-linked sugar chains are species and tissue specific and change in the course of tumorigenesis. Sialyl linkages of human placental glycoproteins are exclusively Neu5Acα2→3Gal, whereas Fucα1→2Gal and Neu5Acα2→6Gal residues are expressed in human chorionic gonadotropin and alkaline phosphatase, which are produced in human choriocarcinoma JEG-3 and BeWo cells. In the present study, to elucidate the enzymological and molecular biological basis of the structural changes that occur in the course of tumorigenesis, α1→2 fucosyltransferase, α2→3 and α2→6 sialyltransferase activities, and the expression levels of the corresponding mRNAs were measured. The α2→3 sialyltransferase activity did not change as a result of tumorigenesis; however, the α2→6 sialyltransferase activity and α1→2 fucosyltransferase activity in JEG-3 and BeWo cells increased to levels several times higher than those in placenta. Competitive PCR analysis showed that the expression levels of mRNA encoding α1→2fucosyltransferase and mRNA encoding α2→6sialyltransferase increased significantly as a result of tumorigenesis, indicating that such structural changes are regulated at the level of transcription of these glycosyltransferase genes.

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This work was supported by grants-in-aid from the Uehara Memorial Foundation and Core Research for Evolutional Science and Technology of Japan Science and Technology Corporation.

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©1998 American Association for Cancer Research.
1998
American Association for Cancer Research, Inc.