Colorectal cancer remains a major medical problem and survival of the patients is directly correlated to the possibility of metastases occurrence. We searched for biochemical differences between colorectal adenocarcinomas and their precursor normal cells with the aim of complementing histological methods for the classification and prognosis of human colorectal tumours. Increased fucosylation is one of the most common phenomena associated with malignant transformation, invasion and metastases. It might be expected that the enzyme alpha-L-fucosidase (alpha-L-fucosidase fucohydrolase E.C.3.2.1.51), involved in the breakdown of fucose-containing glycoproteins and glycolipids, would play an important role in the maintenance of the fucose content of aberrant fucosylated glycoconjugates. Statistical evaluation of 110 patients with colorectal adenocarcinoma has shown that there is a significant decrease of alpha-L-fucosidase activity in the malignant tissue compared with the healthy colonic mucosa of the same patient. Characterisation studies have shown that there are remarkable similarities in the physicochemical and kinetic properties of the enzyme in both tissues. Using an immunodetection assay we conclude that the observed decrease of alpha-L-fucosidase activity is due to a significant decrease of alpha-L-fucosidase protein in colorectal tumours. Our results further demonstrate that the alpha-L-fucosidase content (either as enzymatic activity or as enzymatic protein) is lower in primary tumours at advanced stages (Dukes' B and C) than in primaries at early stages (Dukes' A).

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