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ABSTRACT: Aberrant expression of Lewis antigens has been demonstrated in gastric lesions, namely gastritis, intestinal metaplasia (IM) and gastric carcinoma (GC), and can be partly due to overexpression of the Lewis (FUT3) enzyme. Our aim was to evaluate the role of promoter methylation in FUT3 and Le(a) expression in gastric carcinoma cell lines. MKN45 cell line showed low amounts of Le(a), in the absence of FUT3; GP220 expressed high levels of Le(a) and FUT3. After 5aza-2'deoxycytidine MKN45 showed increased levels of FUT3 and Le(a), by immunohistochemistry and Real-Time PCR, whereas GP220 showed an increase in FUT3 without increase of Le(a). Enzyme activity assays confirmed an increase in alpha-1,4 fucosyltransferase activity in both cell lines by 5aza-2'deoxycytidine. Luciferase reporter gene assays, using methylated and unmethylated deletion constructs of FUT3 promoter, showed that FUT3 expression is regulated by methylation. Summing up, we showed that FUT3 overexpression in gastric cells depends upon promoter hypomethylation and that FUT3 is responsible for overexpression of Le(a) in gastric cells, in vitro. FUT3, Lea, Methylation.
Cancer Letters 11/2006; 242(2):191-7. · 4.24 Impact Factor
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ABSTRACT: Metaplasia, in general, and intestinal metaplasia, in particular, are transdifferentiation processes triggered by environmental aggressions. The heterogeneity of different morphologic variants of metaplasia and distinction from close morphologic entities--heterotopia and hamartoma--is reviewed. Recent data on the characterization of the molecular and epidemiological data involved in the development and progression of lesions of gastric intestinal metaplasia are discussed. A redefinition of intestinal metaplasia is proposed.
Critical reviews in oncogenesis 08/2006; 12(1-2):3-26.
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Epidemiology and Infection 11/2004; 132(5):997-8; author reply 998-9. · 2.84 Impact Factor
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ABSTRACT: Secretor status is defined by the expression of H type 1 antigen on gastric surface epithelium and external secretions. The H type 1 structure, and other fucosylated carbohydrates (Le(a), sialyl-Le(a), Le(b), Le(x), sialyl-Le(x) and Le(y)), can serve as ligands for several pathogens, including Helicobacter pylori, and are cancer-associated antigens. Secretor individuals are more susceptible to some bacterial and viral infections of the genito-urinary and digestive tracts. The aim of the present study was to examine FUT2 (fucosyltransferase 2 gene) polymorphisms in a Caucasian population of non-secretor individuals (n=36) from northern Portugal and to evaluate the activity of the mutant FUT2 enzymes. The secretor status was determined by UEAI [Ulex europaeus (gorse) lectin] histochemistry in gastric mucosa, and FUT2 polymorphisms were studied by restriction-fragment-length polymorphism and direct sequencing. The majority of non-secretors (88.9%) were homozygous for 428G-->A polymorphism; 5.6% were homozygous for 571C-->T and 5.6% were homozygous for two new missense polymorphisms, 739G-->A (2.8%) and 839T-->C (2.8%). By kinetic studies it was demonstrated that the two new FUT2 mutants (739G-->A and 839T-->C) are almost inactive and are responsible for some non-secretor cases.
Biochemical Journal 11/2004; 383(Pt. 3):469-74. · 4.90 Impact Factor
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Epidemiology and Infection 09/2004; 132(05):997 - 999. · 2.84 Impact Factor
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ABSTRACT: Lewis epithelial antigen expression has a role in Helicobacter pylori adherence, presumably mainly in cagA-positive strains. The authors investigated whether Lewis antigen expression in children's gastric mucosa was associated with H. pylori infection, cagA status, patient age, or presence of duodenal ulcer (DU).
The expression of Lewis A (Le(a)), B (Le(b)), X (Le(x)), and Y (Le(y)) was detected by immunohistochemistry in the antral and oxyntic mucosae of 70 children. Children were divided in four age groups (<4 years; 4-8 years; 9-12 years; and 13-18 years).
Forty-seven of the 70 children had H. pylori and 17 had DU. The cagA status was determined by polymerase chain reaction in 34 patients. Le(a) and Le(b) were expressed in 64% and 44% of the patients, respectively; Le(x) and Le(y) were expressed in the glands in all of the patients and in the superficial epithelium. Le(b) expression was more common among patients without H. pylori (15/23, 65%) than in those with H. pylori (16/47, 34%) (P = 0.03). In noninfected patients, Le(b) and superficial Le(y) expression were associated with increased age. Le(b) expression was more common in patients with chronic gastritis than in those with DU. Le(x) superficial expression was significantly associated with DU in patients with H. pylori.
In children, the expression of Le(b) and Le(y) in the superficial gastric epithelium depends on age. Other receptors, such as Le(x), may have a role in H. pylori colonization, especially in patients with DU. Studies assessing the expression of Lewis antigens in children may contribute to an understanding of the mechanisms of acquisition of H. pylori infection.
Journal of Pediatric Gastroenterology and Nutrition 01/2004; 38(1):85-91. · 2.30 Impact Factor
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Patrícia Mesquita,
Nicolas Jonckheere,
Raquel Almeida,
Marie-Paule Ducourouble, Jacinta Serpa,
Elisabete Silva,
Pascal Pigny,
Filipe Santos Silva,
Celso Reis,
Debra Silberg,
Isabelle Van Seuningen,
Leonor David
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ABSTRACT: In intestinal metaplasia and 30% of gastric carcinomas, MUC2 intestinal mucin and the intestine-specific transcription factors Cdx-1 and Cdx-2 are aberrantly expressed. The involvement of Cdx-1 and Cdx-2 in the intestinal development and their role in transcription of several intestinal genes support the hypothesis that Cdx-1 and/or Cdx-2 play important roles in the aberrant intestinal differentiation program of intestinal metaplasia and gastric carcinoma. To clarify the mechanisms of transcriptional regulation of the MUC2 mucin gene in gastric cells, pGL3 deletion constructs covering 2.6 kb of the human MUC2 promoter were used in transient transfection assays, enabling us to identify a relevant region for MUC2 transcription in all gastric cell lines. To evaluate the role of Cdx-1 and Cdx-2 in MUC2 transcription we performed co-transfection experiments with expression vectors encoding Cdx-1 and Cdx-2. In two of the four gastric carcinoma cell lines and in all colon carcinoma cell lines we observed transactivation of the MUC2 promoter by Cdx-2. Using gel shift assays we identified two Cdx-2 binding sites at -177/-171 and -191/-187. Only simultaneous mutation of the two sites resulted in inhibition of Cdx-2-mediated transactivation of MUC2 promoter, implying that both Cdx-2 sites are active. Finally, stable expression of Cdx-2 in a gastric cell line initially not expressing Cdx-2, led to induction of MUC2 expression. In conclusion, this work demonstrates that Cdx-2 activates the expression of MUC2 mucin gene in gastric cells, inducing an intestinal transdifferentiation phenotype that parallels what is observed both in intestinal metaplasia and some gastric carcinomas.
Journal of Biological Chemistry 01/2004; 278(51):51549-56. · 4.77 Impact Factor
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ABSTRACT: The human alpha-1,3/4 fucosyltransferase III (FucT III) catalyses the synthesis of Lewis antigens including Le(b) antigen which is a ligand for Helicobacter pylori adhesion. Several polymorphisms have been described in the FUT3 gene affecting both the transmembrane and catalytic domains, some of which affect the enzyme activity. The aim of the present work was to study the Lewis gene polymorphisms in a Caucasian Portuguese population, with a high rate of H. pylori infection, and to evaluate the implications of mutant enzymes in Le(b) expression in the gastric mucosa. We studied 460 asymptomatic or dyspeptic individuals from northern Portugal. Screening for Lewis gene polymorphisms was performed by SSCP and direct sequencing. Lewis phenotype in gastric mucosa was determined by immunohistochemistry. In 47 individuals with a Lewis negative blood group, we found FUT3 gene polymorphisms that were previously described in other populations: 59T>G, 202T>C, 314C>T, 508G>A and 1067T>A. Among the 47 Lewis negative individuals in blood, only nine were also negative in gastric mucosa, suggesting the existence of another alpha 1-4 fucosyltransferase that is responsible for Le(a) and Le(b) synthesis in gastric mucosa.
Journal of Human Genetics 01/2003; 48(4):183-9. · 2.57 Impact Factor
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ABSTRACT: Mucins and mucin-associated carbohydrates have a distinct expression pattern that can be modified under pathological conditions. Normal gastric mucosa expresses MUC1 and MUC5AC in foveolar epithelium and MUC6 in the glands. Lewis type-1 chain antigens (Le(a) and Le(b)) are expressed in foveolar epithelium, whereas Lewis type-2 chain antigens (Le(x) and Le(y)) are expressed in the glands. In this study we used monoclonal antibodies to evaluate the pattern of mucins and Lewis type-1 carbohydrates in intestinal metaplasia (IM) and compared it with IM types determined using histochemistry. In type-I or complete IM we found expression of MUC2 intestinal mucin and decreased/absent expression of MUC1, MUC5AC and MUC6. In type-II/III or incomplete IM there was co-expression of MUC2 and the mucins expressed in the stomach. No major differences were detected among the three IM types regarding expression of Lewis antigens. Furthermore we observed that sialylated compounds other than sialyl-Le(a) are responsible for histochemical detection of sialomucins and that sulpho-Le(a/c) is expressed in the presence or absence of sulphomucins detected using histochemistry. We conclude that mucin immunohistochemistry may replace classic histochemistry for the classification of IM into complete and incomplete types. The present study challenges the distinction of type-II from type-III IM since we did not observe major differences in the expression profile of mucins and Lewis type-1 carbohydrates. Finally, it seems necessary to evaluate the predictive value of IM according to the presence of specific sulphated carbohydrates (e.g. sulpho-Le(a/c)) rather than histochemically detected sulphomucins.
Archiv für Pathologische Anatomie und Physiologie und für Klinische Medicin 04/2002; 440(3):311-7. · 2.49 Impact Factor
