Changes in the fucose content of haptoglobin in breast and ovarian cancer: Association with disease progression

Abstract

There is increasing evidence for changes in fucosylation in cancer. Previously, we showed that the fucose-specific lectin,Lotus tetragonolobus, extracts an abnormal form of haptoglobin (Hp) from cancer sera. This study investigates the monosaccharide content of Hp obtained from women with ovarian and breast cancer at different stages of their disease. In both cancers, Hp fucose was low when the disease was benign or in remission and much higher when the disease was progressive. This occurred whether the data was expressed per mole of protein or per three mannose residues. Changes in other monosaccharides were minor compared with fucose. There were small increases in theN-acetylglucosamine and galactose content (per three mannoses) in ovarian cancer, suggesting that some glycan chains have increased branching. The latter was independent of disease activity which may be due to some indirect cause such as cytotoxic therapy or an inflammatory response. When ovarian cancer patients were in remission, the number of glycosylation sites on Hp was reduced. Hp isolated from patients with early, but not advanced breast cancer also appeared to have increased glycan branching. The increased fucosylated Hp may interfere with fucose-mediated adhesion reactions of cancer cells.