α(1,2)fucosylation in human colorectal carcinoma

Abstract

Abstract. lewis b and lewis y (le) antigens are known to be elevated in colorectal tumours. Alterations in the catalytic behaviour of gDP-l-fucose:β-D-galactoside α(1,2) fucosyltransferase [α(1,2)Ft, ec: 2.4.1.69], the key enzyme in their synthesis, have been suggested as being responsible for these changes. In particular, an aberrant tumour-specific α(1,2)Ft activity that converts le a and le x to le b and le y determinants, respectively, has been reported in colorectal cancer tissues. to clarify the catalytic function of this enzyme during colorectal tumorigenesis, we analyzed α(1,2)Ft activity levels in healthy and tumour colon specimens using different acceptor substrates and determined the kinetic properties of the enzyme. to complete the study, the aberrant le a /le x α(1,2) fucosylation was determined in healthy and tumour colorectal tissues. A correlation analysis between the activity levels and various standard clinicopathological features, such as tumour stage, was also carried out to elucidate the role of these activities in tumour progression. The results obtained confirm the enhanced α(1,2)fucosylation in colorectal neoplastic tissues and the importance of the aberrant le a /le x α(1,2)Ft activity in this increase. However, taking into account the high levels of le a /le x fucosylation observed in healthy control tissues, we must rule out the idea of a colorectal tumour-specific α(1,2) FT. On the other hand, no significant association was observed between α(1,2)Ft activity levels and the clinicopathological characteristics. overall, our results suggest that α(1,2)Ft activity plays a critical role in the accumulation of le b and le y antigens in human colorectal carcinoma. IntroductionAlterations in glycosylation patterns are one of the characteristics associated with differentiation and malignant transformation (1). the oligosaccharide portions of cellular glycoconjugates, glycolipids and glycoproteins, convey specific immunodeterminants, such as the blood group and related antigens (2). these antigens are known to play an important role in cell recognition, interaction, adhesion and motility. Accordingly, changes in these antigens during carcinogenesis may be crucial in tumour progression and may be involved in extravasation and metastatic phenomena (3).ABo and related determinants are the result of the sequential addition of monosaccharide units to one of the five disaccharide precursors described. type 1 [galβ (1,3)glcnac β1-r] and 2 [gal β(1,4)glcnac β1-r] precursors produce H 1 and H 2 structures, respectively, after the addition of a fucose in α(1,2) linkage to the terminal β-galactosyl residue. H 1 and H 2 determinants can subsequently be converted into le b and le y difucosylated antigens by fucosylation in α(1,4) or α(1,3) linkage, respectively. their positional isomers, the le a and le x antigens, show a similar structure, but the antigens are not fucosylated in α(1,2) (4). Specific alterations of Lewis antigens have been reported in multiple carcinomas and have been correlated with the pr...

Identification of a novel, alpha2-fucosylation-dependent uptake system in highly proliferative cells

“…Of the ten carbohydrate building blocks, alpha-l-fucose seems a critically important pathological effector (Miyoshi et al, 2008;Muinelo-Romay et al, 2011;Wu et al, 2012). In particular, over-expression of alpha2-fucosylated epitopes is reported to be associated with tumor cell phenotypes from multiple tissues, including pancreas (Takiyama et al, 1988), endometrium (Ambros and Kurman, 1993) and colon (Sun et al, 1995;Muinelo-Romay et al, 2010), and down-regulation of fucosyltransferase FUT1 is reported to impair angiogenesis in vitro (Moheler et al, 2008) and to inhibit tumor growth (Zhang et al, 2008). More specifically, alpha2-fucosylated glycans have been indicated as responsible for influencing cell motility and resistance to apoptosis in CD44 variants (Goupille et al, 2000) as well as for regulating functions of nucleolin in CVEC, including those involved in proliferation (Aldi et al, 2009;Palumberi et al, 2010).…”

Decreased Expression of Alpha-L-Fucosidase Gene FUCA1 in Human Colorectal Tumors

“…In CRC, qualitative, quantitative and distributive differences in the expression of glycoconjugates between adenocarcinoma - derived tissue and normal mucosa are well known [6–8]. Among these changes, increased fucosylation has been described and related with malignant transformation, invasion and metastasis [7,9,10]. Fucosylation is influenced by several factors, including the levels and activities of the enzymes involved, the levels of GDP-fucose and other monosaccharide-nucleotides and the transport of these substrates across the membranes of the endoplasmic reticulum and Golgi apparatus.…”

Screening of enzymatic synthesis and expression of Lewis determinants in human colorectal carcinoma

“…The synthesis of colon Le b (and Le y ) antigen is completed by other a(1,2)FT, which directly fucosylates Le a to Le b (and Le x to Le y ) (13). The genetic origin of this a(1,2) FT remains uncertain, but all evidence suggests that both activities are associated with the FUT3 gene encoding the a(1,3/4)FT or Lewis enzyme (31,32).…”

“…In sum, a) changes in H and Lewis antigen expression in colorectal carcinogenesis have been documented; b) the synthesis of these fucosylated determinants requires several tissue-specific FT acting on core 1 and core 2 precursors; and c) the kinetic alterations of some of these enzymes in CRC have recently been reported by our laboratory (13). Despite this background, contradictory data remain, and new insights in this field are required.…”

“…Total cell membranes were obtained as previously described (13). The protein concentration of the enzyme preparations was determined by means of the BCA protein assay, using BSA as the standard.…”