Raquel Almeida | Centro Universitário Una (original) (raw)

Papers by Raquel Almeida

Biochemical and Biophysical Research Communications, 1991

Journal of Endodontics, 1992

Periapical tissue from 58 cases requiring periapical surgery was examined histologically and cult... more Periapical tissue from 58 cases requiring periapical surgery was examined histologically and cultured for the presence of microbes. Twenty-nine had a possible oral cavity communication and 29 did not. Approximately one-half of each biopsy was submitted for culture while the other portion was examined histologically. Cultures were positive for the presence of bacteria in 51 of 58 cases while bacteria were seen histologically in only 8 of 58 cases. A total of 50 different species of bacteria were isolated from the 58 cultures of periapical tissue. Of 133 isolates, 87 were strict anaerobes, 37 were facultative anaerobes, and g were aerobes. Bacteroides species were found in 17 cultures, always with additional bacteria. Seventeen of 58 biopsies contained foreign particulate matter thought to be root canal sealer. Bacteria were found in periapical granulomas, radicular cysts, and a periapical abscess. According to our data, bacteria, foreign material, missed canals, vertical root fractures, and periodontal disease may all contribute to the chronic, nonhealing periradicular lesion.

International Journal of Surgical Pathology, 2002

The HER-2/neu gene or c-erb B-2, localized on chromosome 17q, belongs to a family of tyrosine kin... more The HER-2/neu gene or c-erb B-2, localized on chromosome 17q, belongs to a family of tyrosine kinase receptors and shares extensive homology with the epidermal growth factor receptor. c-erb B-2 gene amplification and protein overexpression have been reported in several human cancers. The prognostic value of this genetic alteration in gastric carcinoma is far from being established. In the present study, formalin-fixed, paraffin-embedded gastric carcinoma tissues from 157 patients were evaluated for c-erb B-2 overexpression, by immunohistochemistry using a polyclonal antibody. c-erb B-2 expression was evaluated according to clinical and pathological parameters, and to the survival of the patients. Our results show that: (1). c-erb B-2 was overexpressed in 15.3% of gastric carcinoma cases; (2). c-erb B-2 overexpression was significantly more frequent in cardia (23.8%) and fundus/body (25.0%) carcinomas than in antrum (7.2%) carcinomas; (3). c-erb B-2 overexpression was significantly associated with venous invasion; (4). c-erb B-2 is a prognostic factor for gastric carcinoma.

Biochimica Et Biophysica Acta-general Subjects, 1999

Enzymatic glycosylation of proteins and lipids is an abundant and important biological process. A... more Enzymatic glycosylation of proteins and lipids is an abundant and important biological process. A great diversity of oligosaccharide structures and types of glycoconjugates is found in nature, and these are synthesized by a large number of glycosyltransferases. Glycosyltransferases have high donor and acceptor substrate specificities and are in general limited to catalysis of one unique glycosidic linkage. Emerging evidence indicates that formation of many glycosidic linkages is covered by large homologous glycosyltransferase gene families, and that the existence of multiple enzyme isoforms provides a degree of redundancy as well as a higher level of regulation of the glycoforms synthesized. Here, we discuss recent cloning strategies enabling the identification of these large glycosyltransferase gene families and exemplify the implication this has for our understanding of regulation of glycosylation by discussing two galactosyltransferase gene families. ß

Journal of Pathology, 2008

Helicobacter pylori infection induces intestinal metaplasia of the stomach, a preneoplastic lesio... more Helicobacter pylori infection induces intestinal metaplasia of the stomach, a preneoplastic lesion associated with an increased risk for gastric cancer development. Intestinal metaplasia is induced by the intestine-specific transcription factor CDX2 but the mechanisms responsible for this ectopic expression have never been described. We hypothesized that the BMP/SMAD pathway has a role in CDX2 regulation, in this context, for the following reasons: (1) the BMP pathway is crucial for normal intestinal differentiation and (2) there is an influx of BMP2 and BMP4-producing cells to the stomach upon Helicobacter pylori infection. We evaluated the expression of key elements of the BMP pathway in human stomach specimens with IM. Growth factor treatments, with BMP2 and BMP4, were performed in cultured cells and a knock-down experiment of SMAD4 was done using RNAi. We showed overexpression in IM of BMP2/4, BMPR1A, and SMAD4 in 56% of IM foci, and pSMAD1/5/8 in 100% of IM foci as compared to adjacent mucosa. In vitro, treatment of AGS cells with BMP2 and BMP4 increased endogenous CDX2 expression as well as the intestinal differentiation markers MUC2 and LI-cadherin. On the other hand, SMAD4 knock-down led to decreased endogenous CDX2, MUC2, and LI-cadherin in AGS. Treatment of the SMAD4 knock-down cells had no influence on CDX2 expression as opposed to wild-type cells. A 9.3 kb CDX2 promoter could be transactivated by SMAD4 and SMAD1 in a cell-dependent manner. In conclusion, we identified for the first time that the BMP pathway is active in intestinal metaplasia and that BMP2 and BMP4 regulate CDX2 expression and promote intestinal differentiation through the canonical signal transducers. Copyright © 2008 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

Cancer Letters, 2003

In the present work we investigated the methylation levels of mucin gene (MUC)2 promoter region i... more In the present work we investigated the methylation levels of mucin gene (MUC)2 promoter region in normal gastric mucosa and mucinous gastric carcinoma in order to access if the observed de novo expression of the intestinal mucin MUC2 in mucinous gastric carcinoma is associated with changes in MUC2 promoter methylation status. The results obtained by methylation-sensitive single nucleotide primer extension suggest that MUC2 expression in gastric cells is regulated by promoter methylation and further indicate that two specific cytosine guaine dinucleotide (CpG) sites may play a particularly important regulatory role. q

Journal of Pathology, 2005

Intestinal metaplasia (IM) is a preneoplastic lesion of the stomach in which there is transdiffer... more Intestinal metaplasia (IM) is a preneoplastic lesion of the stomach in which there is transdifferentiation of the gastric mucosa to an intestinal phenotype. The caudal-related homeobox gene CDX2 encodes an intestine-specific transcription factor crucial for the regulation of proliferation and differentiation of intestinal cells. In addition, CDX2 is involved in the induction of IM in the stomach. The aim of this study was to access the putative involvement of OCT-1 in the induction of CDX2 expression de novo in gastric mucosa leading to the onset of IM. OCT-1 protein expression was evaluated by immunohistochemistry in 31 biopsies with chronic gastritis, 15 biopsies with foci of IM and adjacent gastric mucosa and 42 gastric carcinomas. Furthermore, we evaluated OCT-1 binding by electrophoretic mobility shift assay and activation of the CDX2 promoter by co-transfecting a CDX2 promoter/reporter construct with an OCT-1 expression vector in two gastric carcinoma cell lines, GP220 and MKN45. Our results show that OCT-1 is expressed in chronic gastritis, particularly when it is adjacent to IM and is expressed in 87% of IM foci. Furthermore, 74% of the gastric carcinomas were positive for OCT-1 and a strong association was observed between OCT-1 expression and intestinal-type carcinoma. We identified that OCT-1 binds to the CDX2 promoter, although we could not see a transactivation effect in gastric carcinoma cell lines. In conclusion, we observed increased OCT-1 expression in IM and in intestinal gastric carcinomas and identified the capacity of OCT-1 to bind to the CDX2 promoter, although we could not demonstrate a direct effect of OCT-1 in the transactivation of CDX2. Copyright © 2005 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

Virchows Archiv, 2009

We estimated the prevalence of Helicobacter pylori infection, chronic gastritis, atrophy, and int... more We estimated the prevalence of Helicobacter pylori infection, chronic gastritis, atrophy, and intestinal metaplasia in dyspeptic patients from Maputo Central Hospital, Mozambique and evaluated the relationship between infection and histopathological features of chronic gastritis. Biopsies from 109 consecutive patients observed in 2005–2006 were collected from antrum, incisura angularis, and corpus for histopathological study according to the Modified Sydney system. H. pylori infection was assessed by histology and polymerase chain reaction. H. pylori prevalence was 94.5%. Chronic gastritis was the most frequent diagnosis (90.8%). Degenerative surface epithelial damage was associated with higher H. pylori density. Glandular atrophy (8.3%) and intestinal metaplasia (8.3%) were infrequent. Our results confirm previous observations in African countries with high prevalence of H. pylori infection and low rates of gastric cancer: high frequency of chronic H. pylori-associated gastritis with very low frequency of gastric atrophy and intestinal metaplasia.

Cancer Letters, 2006

Aberrant expression of Lewis antigens has been demonstrated in gastric lesions, namely gastritis,... more 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.

Journal of Histochemistry & Cytochemistry, 2003

European Journal of Human Genetics, 2003

Gastric cancer (GC) stands as the second most common cause of cancer death for males worldwide, a... more Gastric cancer (GC) stands as the second most common cause of cancer death for males worldwide, and intestinal metaplasia (IM) is a lesion that precedes GC development. In previous works it was shown that polymorphisms of MUC1 gene are associated with increased risk for GC and IM. The aim of the present study was to evaluate MUC1 gene polymorphism in patients with chronic gastritis from Colombia. A Portuguese population of patients with chronic gastritis was used for comparative purposes. A total of 67 Colombian cases and 52 Portuguese cases were analysed by restriction analysis and Southern blotting. MUC1 allele frequencies were significantly different between the two populations, with an overall prevalence of smaller alleles in Colombian samples. Colombian cases showed a lower prevalence of individuals homozygous for small MUC1 mucins in cases without IM (62.5%) when compared with cases with IM (86.0%). The same trend, although not statistically significant, is observed in the Portuguese population. In conclusion, our study shows that Colombian patients with chronic gastritis have a significantly higher prevalence of small MUC1 alleles than the Portuguese population. Our study also shows that small MUC1 genotypes are associated with increased risk for IM development in Colombian patients.

BLAST analysis of expressed sequence tags (ESTs) using the coding sequence of the human UDP-galac... more BLAST analysis of expressed sequence tags (ESTs) using the coding sequence of the human UDP-galactose:beta-N-acetylglucosamine beta1, 4-galactosyltransferase, designated beta4Gal-T1, revealed a large number of ESTs with identical as well as similar sequences. ESTs with sequences similar to that of beta4Gal-T1 could be grouped into at least two non-identical sequence sets. Analysis of the predicted amino acid sequence of the novel ESTs with beta4Gal-T1 revealed conservation of short sequence motifs as well as cysteine residues previously shown to be important for the function of beta4Gal-T1. The likelihood that the identified ESTs represented novel galactosyltransferase genes was tested by cloning and sequencing of the full coding region of two distinct genes, followed by expression. Expression of soluble secreted constructs in the baculovirus system showed that these genes represented genuine UDP-galactose:beta-N-acetylglucosamine beta1, 4-galactosyltransferases, thus designated beta4Gal-T2 and beta4Gal-T3. Genomic cloning of the genes revealed that they have identical genomic organizations compared with beta4Gal-T1. The two novel genes were located on 1p32-33 and 1q23. The results demonstrate the existence of a family of homologous galactosyltransferases with related functions. The existence of multiple beta4-galactosyltransferases with the same or overlapping functions may be relevant for interpretation of biological functions previously assigned to beta4Gal-T1.

The Sialyl-Tn antigen (Neu5Ac␣2-6GalNAc-O-Ser/Thr) is highly expressed in several human carcinoma... more The Sialyl-Tn antigen (Neu5Ac␣2-6GalNAc-O-Ser/Thr) is highly expressed in several human carcinomas and is associated with carcinoma aggressiveness and poor prognosis. We characterized two human sialyltransferases, CMP-Neu5Ac:GalNAc-R ␣2,6-sialyltransferase (ST6GalNAc)-I and ST6GalNAc-II, that are candidate enzymes for Sialyl-Tn synthases. We expressed soluble recombinant hST6GalNAc-I and hST6GalNAc-II and characterized the substrate specificity of both enzymes toward a panel of glycopeptides, glycoproteins, and other synthetic glycoconjugates. The recombinant ST6GalNAc-I and ST6GalNAc-II showed similar substrate specificity toward glycoproteins and GalNAc␣-O-Ser/Thr glycopeptides, such as glycopeptides derived from the MUC2 mucin and the HIVgp120. We also observed that the amino acid sequence of the acceptor glycopeptide contributes to the in vitro substrate specificity of both enzymes.

Aberrant glycosylation of mucins is a common phenomenon associated with oncogenic transformation.... more Aberrant glycosylation of mucins is a common phenomenon associated with oncogenic transformation. We investigated the association between expression of the tumor-associated antigens T, Tn, and sialyl-Tn and polymorphism in the length of the MUC1 mucin tandem repeat in a series of gastric carcinomas. We further evaluated the relevance of MUC1 tandem repeat length on the expression of these tumor-associated carbohydrate antigens (TACAs) using a gastric carcinoma cell line model expressing recombinant MUC1 constructs carrying 0, 3, 9, and 42 repeats. Gastric carcinomas showed a high prevalence of Tn and sialyl-Tn antigens, whereas T antigen was less frequently expressed. The expression of T antigen was significantly higher in gastric carcinomas from patients homozygous for MUC1 large tandem repeat alleles. No significant associations were found for Tn and sialyl-Tn antigens. This novel association was reinforced by the gastric carcinoma cell line model experiments, where de novo expression of T antigen was detected in clones transfected with larger VNTR regions. Our results indicate that polymorphism in the MUC1 tandem repeat influences the expression of TACAs in gastric cancer cells and may therefore allow the identification of subgroups of patients that develop more aggressive tumors expressing T antigen.

Journal of Human Genetics, 2003

The human α-1,3/4 fucosyltransferase III (FucT III) catalyses the synthesis of Lewis antigens inc... more The human α-1,3/4 fucosyltransferase III (FucT III) catalyses the synthesis of Lewis antigens including Leb 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 Leb 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 α 1-4 fucosyltransferase that is responsible for Lea and Leb synthesis in gastric mucosa.

Journal of Pathology, 2003

Intestinal metaplasia (IM) is part of a stepwise sequence of alterations of the gastric mucosa, l... more Intestinal metaplasia (IM) is part of a stepwise sequence of alterations of the gastric mucosa, leading ultimately to gastric cancer, and is strongly associated with chronic Helicobacter pylori infection. The molecular mechanisms underlying the onset of IM remain elusive. The aim of this study was to assess the putative involvement of two intestine-specific transcription factors, CDX1 and CDX2, in the pathogenesis of gastric IM and gastric carcinoma. Eighteen foci of IM and 46 cases of gastric carcinoma were evaluated by immunohistochemistry for CDX1 and CDX2 expression. CDX1 was expressed in all foci of IM and in 41% of gastric carcinomas; CDX2 was expressed in 17/18 foci of IM and in 54% of gastric carcinomas. In gastric carcinomas, a strong association was observed between the expression of CDX1 and CDX2, as well as between the intestinal mucin MUC2 and CDX1 and CDX2. No association was observed between the expression of CDX1 and CDX2 and the histological type of gastric carcinoma. In conclusion, these results show that aberrant expression of CDX1 and CDX2 is consistently observed in IM and in a subset of gastric carcinomas. The association of CDX1 and CDX2 with expression of the intestinal mucin MUC2, both in IM and in gastric carcinoma, indirectly implies that CDX1 and CDX2 may be involved in intestinal differentiation along the gastric carcinogenesis pathway. Copyright © 2002 John Wiley & Sons, Ltd.

Biochemical Journal, 2004

Secretor status is defined by the expression of H type 1 antigen on gastric surface epithelium an... more 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.

European Journal of Human Genetics, 2001

MUC1 like most mucin genes shows extensive length polymorphism in the central core region. In a p... more MUC1 like most mucin genes shows extensive length polymorphism in the central core region. In a previous study it was shown that individuals with small MUC1 alleles/genotypes have an increased risk for development of gastric carcinoma. Our aim was to see if MUC1 gene polymorphism was involved in susceptibility for the development of conditions that precede gastric carcinoma: chronic atrophic gastritis (CAG) and intestinal metaplasia (IM). We evaluated MUC1 polymorphism in a population of 174 individuals with chronic gastritis (CG) displaying (CAG) and/or intestinal metaplasia (IM). The population of patients with CG shows MUC1 allele frequencies significantly different from the gastric carcinoma patients and blood donors population. A significantly lower frequency of CAG and IM was observed in MUC1 VNTR heterozygotic patients. Within the group of patients with IM, MUC1 large VNTR homozygotes show a significantly higher frequency of complete IM while small VNTR homozygotes show a significantly higher frequency of incomplete IM. These findings show that MUC1 polymorphism may define different susceptibility backgrounds for the development of conditions that precede gastric carcinoma: chronic atrophic gastritis (CAG) and intestinal metaplasia (IM). European Journal of Human Genetics (2001) 9, 548 ± 552.

Current Opinion in Immunology, 1993

Avaliação Final parte 1 A

Biochemical and Biophysical Research Communications, 1991

Journal of Endodontics, 1992

Periapical tissue from 58 cases requiring periapical surgery was examined histologically and cult... more Periapical tissue from 58 cases requiring periapical surgery was examined histologically and cultured for the presence of microbes. Twenty-nine had a possible oral cavity communication and 29 did not. Approximately one-half of each biopsy was submitted for culture while the other portion was examined histologically. Cultures were positive for the presence of bacteria in 51 of 58 cases while bacteria were seen histologically in only 8 of 58 cases. A total of 50 different species of bacteria were isolated from the 58 cultures of periapical tissue. Of 133 isolates, 87 were strict anaerobes, 37 were facultative anaerobes, and g were aerobes. Bacteroides species were found in 17 cultures, always with additional bacteria. Seventeen of 58 biopsies contained foreign particulate matter thought to be root canal sealer. Bacteria were found in periapical granulomas, radicular cysts, and a periapical abscess. According to our data, bacteria, foreign material, missed canals, vertical root fractures, and periodontal disease may all contribute to the chronic, nonhealing periradicular lesion.

International Journal of Surgical Pathology, 2002

The HER-2/neu gene or c-erb B-2, localized on chromosome 17q, belongs to a family of tyrosine kin... more The HER-2/neu gene or c-erb B-2, localized on chromosome 17q, belongs to a family of tyrosine kinase receptors and shares extensive homology with the epidermal growth factor receptor. c-erb B-2 gene amplification and protein overexpression have been reported in several human cancers. The prognostic value of this genetic alteration in gastric carcinoma is far from being established. In the present study, formalin-fixed, paraffin-embedded gastric carcinoma tissues from 157 patients were evaluated for c-erb B-2 overexpression, by immunohistochemistry using a polyclonal antibody. c-erb B-2 expression was evaluated according to clinical and pathological parameters, and to the survival of the patients. Our results show that: (1). c-erb B-2 was overexpressed in 15.3% of gastric carcinoma cases; (2). c-erb B-2 overexpression was significantly more frequent in cardia (23.8%) and fundus/body (25.0%) carcinomas than in antrum (7.2%) carcinomas; (3). c-erb B-2 overexpression was significantly associated with venous invasion; (4). c-erb B-2 is a prognostic factor for gastric carcinoma.

Biochimica Et Biophysica Acta-general Subjects, 1999

Enzymatic glycosylation of proteins and lipids is an abundant and important biological process. A... more Enzymatic glycosylation of proteins and lipids is an abundant and important biological process. A great diversity of oligosaccharide structures and types of glycoconjugates is found in nature, and these are synthesized by a large number of glycosyltransferases. Glycosyltransferases have high donor and acceptor substrate specificities and are in general limited to catalysis of one unique glycosidic linkage. Emerging evidence indicates that formation of many glycosidic linkages is covered by large homologous glycosyltransferase gene families, and that the existence of multiple enzyme isoforms provides a degree of redundancy as well as a higher level of regulation of the glycoforms synthesized. Here, we discuss recent cloning strategies enabling the identification of these large glycosyltransferase gene families and exemplify the implication this has for our understanding of regulation of glycosylation by discussing two galactosyltransferase gene families. ß

Journal of Pathology, 2008

Helicobacter pylori infection induces intestinal metaplasia of the stomach, a preneoplastic lesio... more Helicobacter pylori infection induces intestinal metaplasia of the stomach, a preneoplastic lesion associated with an increased risk for gastric cancer development. Intestinal metaplasia is induced by the intestine-specific transcription factor CDX2 but the mechanisms responsible for this ectopic expression have never been described. We hypothesized that the BMP/SMAD pathway has a role in CDX2 regulation, in this context, for the following reasons: (1) the BMP pathway is crucial for normal intestinal differentiation and (2) there is an influx of BMP2 and BMP4-producing cells to the stomach upon Helicobacter pylori infection. We evaluated the expression of key elements of the BMP pathway in human stomach specimens with IM. Growth factor treatments, with BMP2 and BMP4, were performed in cultured cells and a knock-down experiment of SMAD4 was done using RNAi. We showed overexpression in IM of BMP2/4, BMPR1A, and SMAD4 in 56% of IM foci, and pSMAD1/5/8 in 100% of IM foci as compared to adjacent mucosa. In vitro, treatment of AGS cells with BMP2 and BMP4 increased endogenous CDX2 expression as well as the intestinal differentiation markers MUC2 and LI-cadherin. On the other hand, SMAD4 knock-down led to decreased endogenous CDX2, MUC2, and LI-cadherin in AGS. Treatment of the SMAD4 knock-down cells had no influence on CDX2 expression as opposed to wild-type cells. A 9.3 kb CDX2 promoter could be transactivated by SMAD4 and SMAD1 in a cell-dependent manner. In conclusion, we identified for the first time that the BMP pathway is active in intestinal metaplasia and that BMP2 and BMP4 regulate CDX2 expression and promote intestinal differentiation through the canonical signal transducers. Copyright © 2008 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

Cancer Letters, 2003

In the present work we investigated the methylation levels of mucin gene (MUC)2 promoter region i... more In the present work we investigated the methylation levels of mucin gene (MUC)2 promoter region in normal gastric mucosa and mucinous gastric carcinoma in order to access if the observed de novo expression of the intestinal mucin MUC2 in mucinous gastric carcinoma is associated with changes in MUC2 promoter methylation status. The results obtained by methylation-sensitive single nucleotide primer extension suggest that MUC2 expression in gastric cells is regulated by promoter methylation and further indicate that two specific cytosine guaine dinucleotide (CpG) sites may play a particularly important regulatory role. q

Journal of Pathology, 2005

Intestinal metaplasia (IM) is a preneoplastic lesion of the stomach in which there is transdiffer... more Intestinal metaplasia (IM) is a preneoplastic lesion of the stomach in which there is transdifferentiation of the gastric mucosa to an intestinal phenotype. The caudal-related homeobox gene CDX2 encodes an intestine-specific transcription factor crucial for the regulation of proliferation and differentiation of intestinal cells. In addition, CDX2 is involved in the induction of IM in the stomach. The aim of this study was to access the putative involvement of OCT-1 in the induction of CDX2 expression de novo in gastric mucosa leading to the onset of IM. OCT-1 protein expression was evaluated by immunohistochemistry in 31 biopsies with chronic gastritis, 15 biopsies with foci of IM and adjacent gastric mucosa and 42 gastric carcinomas. Furthermore, we evaluated OCT-1 binding by electrophoretic mobility shift assay and activation of the CDX2 promoter by co-transfecting a CDX2 promoter/reporter construct with an OCT-1 expression vector in two gastric carcinoma cell lines, GP220 and MKN45. Our results show that OCT-1 is expressed in chronic gastritis, particularly when it is adjacent to IM and is expressed in 87% of IM foci. Furthermore, 74% of the gastric carcinomas were positive for OCT-1 and a strong association was observed between OCT-1 expression and intestinal-type carcinoma. We identified that OCT-1 binds to the CDX2 promoter, although we could not see a transactivation effect in gastric carcinoma cell lines. In conclusion, we observed increased OCT-1 expression in IM and in intestinal gastric carcinomas and identified the capacity of OCT-1 to bind to the CDX2 promoter, although we could not demonstrate a direct effect of OCT-1 in the transactivation of CDX2. Copyright © 2005 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

Virchows Archiv, 2009

We estimated the prevalence of Helicobacter pylori infection, chronic gastritis, atrophy, and int... more We estimated the prevalence of Helicobacter pylori infection, chronic gastritis, atrophy, and intestinal metaplasia in dyspeptic patients from Maputo Central Hospital, Mozambique and evaluated the relationship between infection and histopathological features of chronic gastritis. Biopsies from 109 consecutive patients observed in 2005–2006 were collected from antrum, incisura angularis, and corpus for histopathological study according to the Modified Sydney system. H. pylori infection was assessed by histology and polymerase chain reaction. H. pylori prevalence was 94.5%. Chronic gastritis was the most frequent diagnosis (90.8%). Degenerative surface epithelial damage was associated with higher H. pylori density. Glandular atrophy (8.3%) and intestinal metaplasia (8.3%) were infrequent. Our results confirm previous observations in African countries with high prevalence of H. pylori infection and low rates of gastric cancer: high frequency of chronic H. pylori-associated gastritis with very low frequency of gastric atrophy and intestinal metaplasia.

Cancer Letters, 2006

Aberrant expression of Lewis antigens has been demonstrated in gastric lesions, namely gastritis,... more 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.

Journal of Histochemistry & Cytochemistry, 2003

European Journal of Human Genetics, 2003

Gastric cancer (GC) stands as the second most common cause of cancer death for males worldwide, a... more Gastric cancer (GC) stands as the second most common cause of cancer death for males worldwide, and intestinal metaplasia (IM) is a lesion that precedes GC development. In previous works it was shown that polymorphisms of MUC1 gene are associated with increased risk for GC and IM. The aim of the present study was to evaluate MUC1 gene polymorphism in patients with chronic gastritis from Colombia. A Portuguese population of patients with chronic gastritis was used for comparative purposes. A total of 67 Colombian cases and 52 Portuguese cases were analysed by restriction analysis and Southern blotting. MUC1 allele frequencies were significantly different between the two populations, with an overall prevalence of smaller alleles in Colombian samples. Colombian cases showed a lower prevalence of individuals homozygous for small MUC1 mucins in cases without IM (62.5%) when compared with cases with IM (86.0%). The same trend, although not statistically significant, is observed in the Portuguese population. In conclusion, our study shows that Colombian patients with chronic gastritis have a significantly higher prevalence of small MUC1 alleles than the Portuguese population. Our study also shows that small MUC1 genotypes are associated with increased risk for IM development in Colombian patients.

BLAST analysis of expressed sequence tags (ESTs) using the coding sequence of the human UDP-galac... more BLAST analysis of expressed sequence tags (ESTs) using the coding sequence of the human UDP-galactose:beta-N-acetylglucosamine beta1, 4-galactosyltransferase, designated beta4Gal-T1, revealed a large number of ESTs with identical as well as similar sequences. ESTs with sequences similar to that of beta4Gal-T1 could be grouped into at least two non-identical sequence sets. Analysis of the predicted amino acid sequence of the novel ESTs with beta4Gal-T1 revealed conservation of short sequence motifs as well as cysteine residues previously shown to be important for the function of beta4Gal-T1. The likelihood that the identified ESTs represented novel galactosyltransferase genes was tested by cloning and sequencing of the full coding region of two distinct genes, followed by expression. Expression of soluble secreted constructs in the baculovirus system showed that these genes represented genuine UDP-galactose:beta-N-acetylglucosamine beta1, 4-galactosyltransferases, thus designated beta4Gal-T2 and beta4Gal-T3. Genomic cloning of the genes revealed that they have identical genomic organizations compared with beta4Gal-T1. The two novel genes were located on 1p32-33 and 1q23. The results demonstrate the existence of a family of homologous galactosyltransferases with related functions. The existence of multiple beta4-galactosyltransferases with the same or overlapping functions may be relevant for interpretation of biological functions previously assigned to beta4Gal-T1.

The Sialyl-Tn antigen (Neu5Ac␣2-6GalNAc-O-Ser/Thr) is highly expressed in several human carcinoma... more The Sialyl-Tn antigen (Neu5Ac␣2-6GalNAc-O-Ser/Thr) is highly expressed in several human carcinomas and is associated with carcinoma aggressiveness and poor prognosis. We characterized two human sialyltransferases, CMP-Neu5Ac:GalNAc-R ␣2,6-sialyltransferase (ST6GalNAc)-I and ST6GalNAc-II, that are candidate enzymes for Sialyl-Tn synthases. We expressed soluble recombinant hST6GalNAc-I and hST6GalNAc-II and characterized the substrate specificity of both enzymes toward a panel of glycopeptides, glycoproteins, and other synthetic glycoconjugates. The recombinant ST6GalNAc-I and ST6GalNAc-II showed similar substrate specificity toward glycoproteins and GalNAc␣-O-Ser/Thr glycopeptides, such as glycopeptides derived from the MUC2 mucin and the HIVgp120. We also observed that the amino acid sequence of the acceptor glycopeptide contributes to the in vitro substrate specificity of both enzymes.

Aberrant glycosylation of mucins is a common phenomenon associated with oncogenic transformation.... more Aberrant glycosylation of mucins is a common phenomenon associated with oncogenic transformation. We investigated the association between expression of the tumor-associated antigens T, Tn, and sialyl-Tn and polymorphism in the length of the MUC1 mucin tandem repeat in a series of gastric carcinomas. We further evaluated the relevance of MUC1 tandem repeat length on the expression of these tumor-associated carbohydrate antigens (TACAs) using a gastric carcinoma cell line model expressing recombinant MUC1 constructs carrying 0, 3, 9, and 42 repeats. Gastric carcinomas showed a high prevalence of Tn and sialyl-Tn antigens, whereas T antigen was less frequently expressed. The expression of T antigen was significantly higher in gastric carcinomas from patients homozygous for MUC1 large tandem repeat alleles. No significant associations were found for Tn and sialyl-Tn antigens. This novel association was reinforced by the gastric carcinoma cell line model experiments, where de novo expression of T antigen was detected in clones transfected with larger VNTR regions. Our results indicate that polymorphism in the MUC1 tandem repeat influences the expression of TACAs in gastric cancer cells and may therefore allow the identification of subgroups of patients that develop more aggressive tumors expressing T antigen.

Journal of Human Genetics, 2003

The human α-1,3/4 fucosyltransferase III (FucT III) catalyses the synthesis of Lewis antigens inc... more The human α-1,3/4 fucosyltransferase III (FucT III) catalyses the synthesis of Lewis antigens including Leb 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 Leb 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 α 1-4 fucosyltransferase that is responsible for Lea and Leb synthesis in gastric mucosa.

Journal of Pathology, 2003

Intestinal metaplasia (IM) is part of a stepwise sequence of alterations of the gastric mucosa, l... more Intestinal metaplasia (IM) is part of a stepwise sequence of alterations of the gastric mucosa, leading ultimately to gastric cancer, and is strongly associated with chronic Helicobacter pylori infection. The molecular mechanisms underlying the onset of IM remain elusive. The aim of this study was to assess the putative involvement of two intestine-specific transcription factors, CDX1 and CDX2, in the pathogenesis of gastric IM and gastric carcinoma. Eighteen foci of IM and 46 cases of gastric carcinoma were evaluated by immunohistochemistry for CDX1 and CDX2 expression. CDX1 was expressed in all foci of IM and in 41% of gastric carcinomas; CDX2 was expressed in 17/18 foci of IM and in 54% of gastric carcinomas. In gastric carcinomas, a strong association was observed between the expression of CDX1 and CDX2, as well as between the intestinal mucin MUC2 and CDX1 and CDX2. No association was observed between the expression of CDX1 and CDX2 and the histological type of gastric carcinoma. In conclusion, these results show that aberrant expression of CDX1 and CDX2 is consistently observed in IM and in a subset of gastric carcinomas. The association of CDX1 and CDX2 with expression of the intestinal mucin MUC2, both in IM and in gastric carcinoma, indirectly implies that CDX1 and CDX2 may be involved in intestinal differentiation along the gastric carcinogenesis pathway. Copyright © 2002 John Wiley & Sons, Ltd.

Biochemical Journal, 2004

Secretor status is defined by the expression of H type 1 antigen on gastric surface epithelium an... more 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.

European Journal of Human Genetics, 2001

MUC1 like most mucin genes shows extensive length polymorphism in the central core region. In a p... more MUC1 like most mucin genes shows extensive length polymorphism in the central core region. In a previous study it was shown that individuals with small MUC1 alleles/genotypes have an increased risk for development of gastric carcinoma. Our aim was to see if MUC1 gene polymorphism was involved in susceptibility for the development of conditions that precede gastric carcinoma: chronic atrophic gastritis (CAG) and intestinal metaplasia (IM). We evaluated MUC1 polymorphism in a population of 174 individuals with chronic gastritis (CG) displaying (CAG) and/or intestinal metaplasia (IM). The population of patients with CG shows MUC1 allele frequencies significantly different from the gastric carcinoma patients and blood donors population. A significantly lower frequency of CAG and IM was observed in MUC1 VNTR heterozygotic patients. Within the group of patients with IM, MUC1 large VNTR homozygotes show a significantly higher frequency of complete IM while small VNTR homozygotes show a significantly higher frequency of incomplete IM. These findings show that MUC1 polymorphism may define different susceptibility backgrounds for the development of conditions that precede gastric carcinoma: chronic atrophic gastritis (CAG) and intestinal metaplasia (IM). European Journal of Human Genetics (2001) 9, 548 ± 552.

Current Opinion in Immunology, 1993

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