N-glycolylneuraminic acid in human tumours

N-Glycolylneuraminic acid (Neu5Gc) is an abundant sialic acid, occurring in the glycoconjugates. of most deuterostome animals. Homo sapiens is a notab le exception, since Neu5Gc is effectively absent from normal human tissues. This is due to a deletion in the human gene coding for CMP-Neu5Ac hydroxyl ase, the enzyme usually responsible for Neu5Gc biosynthesis. Despite this m utation, persistent reports in the literature suggest that Neu5Gc occurs in the glycoconjugates of many human tumours, where it might be responsible f or the formation of so-called Hanganutziu-Deicher antibodies. However, the variety of systems studied and the various experimental approaches adopted have yielded a complex picture of Neu5Gc occurrence in human neoplasias. Th e aim of this paper is therefore to provide a critical review of the eviden ce for Neu5Gc in human tumours, paying particular attention to the analytic al methods employed. The possible clinical applications of Neu5Gc-containin g glycoconjugates and Hanganutziu-Deicher antibodies in the diagnosis and t reatment of breast cancer and melanoma are also discussed. In view of the l ack of CMP-Neu5Ac hydroxylase in human cells, alternative metabolic pathway s for the biosynthesis of glycoconjugate-bound Neu5Gc are considered. (C) 2 001 Societe francaise de biochimie et biologic moleculaire / Editions scien titiques et medicales Elsevier SAS. All rights reserved.