RESUMEN
OBJECTIVE: We aimed to evaluate the inactivation of COX-2, HMLH1 and CDKN2A by promoter methylation and its relationship with the infection by different Helicobacter pylori strains in gastric cancer. METHODS: DNA extracted from 76 H. pylori-positive gastric tumor samples was available for promoter methylation identification by methylation-specific PCR and H. pylori subtyping by PCR. Immunohistochemistry was used to determine COX-2, p16(INK4A) and HMLH1 expression. RESULTS: A strong negative correlation was found between the expression of these markers and the presence of promoter methylation in their genes. Among cardia tumors, negativity of p16(INK4A) was a significant finding. On the other hand, in noncardia tumors, the histological subtypes had different gene expression patterns. In the intestinal subtype, a significant finding was HMLH1 inactivation by methylation, while in the diffuse subtype, CDKN2A inactivation by methylation was the significant finding. Tumors with methylated COX-2 and HMLH1 genes were associated with H. pylori vacA s1 (p = 0.025 and 0.047, respectively), and the nonmethylated tumors were associated with the presence of the gene flaA. CONCLUSIONS: These data suggest that the inactivation of these genes by methylation occurs by distinct pathways according to the histological subtype and tumor location and depends on the H. pylori genotype.
Asunto(s)
Adenocarcinoma/genética , Adenocarcinoma/microbiología , Adenocarcinoma/patología , Genes p16 , Neoplasias Gástricas/genética , Neoplasias Gástricas/microbiología , Neoplasias Gástricas/patología , Proteínas Adaptadoras Transductoras de Señales/genética , Anciano , Ciclooxigenasa 2/genética , Metilación de ADN , Femenino , Genotipo , Infecciones por Helicobacter/complicaciones , Infecciones por Helicobacter/genética , Infecciones por Helicobacter/microbiología , Helicobacter pylori/genética , Humanos , Inmunohistoquímica , Masculino , Persona de Mediana Edad , Homólogo 1 de la Proteína MutL , Estadificación de Neoplasias , Proteínas Nucleares/genética , Reacción en Cadena de la Polimerasa , Regiones Promotoras Genéticas/genéticaRESUMEN
Evidence suggests that the carcinogenic process guided by Helicobacter pylori is related to the expression of cell cycle and apoptosis proteins as BCL-2, BAX, and MYC. However, the literature is conflicting regarding the expression frequency in the histological subtypes and did not consider cagA gene presence. To investigate the expression of these proteins considering the histological subtypes of gastric cancer associated with H. pylori (cagA), a total of 89 cases were used. H. pylori infection and cagA status were determined by PCR. Immunodetection was performed for MYC, BCL-2, and BAX proteins. H. pylori was found in 95.5% of the patients, among them, 65.8% were cagA(+). Nuclear MYC was detected in 36.4%, BAX in 55.7%, while BCl-2 in just 5%. Nuclear MYC staining was significantly lower in the intestinal than diffuse subtype (p = 0.008) and was related with the presence of H. pylori cagA(+). Additionally, most of the few cases cytoplasmic MYC positive were in the intestinal subtype. In diffuse tumors, although most nuclear MYC positive cases were cagA(+), it was not significant. No difference was observed between BCL-2 or BAX expression considering the presence of cagA gene in the histological subtypes. It seems that MYC could be relevant for the diffuse tumorigenic pathway associated with H. pylori and possibly influenced by the presence of cagA gene, while in intestinal tumors, the tumorigenic pathway does not occur through the MYC expression.
Asunto(s)
Adenocarcinoma/metabolismo , Helicobacter pylori/aislamiento & purificación , Neoplasias Intestinales/metabolismo , Proteínas Proto-Oncogénicas c-myc/metabolismo , Neoplasias Gástricas/metabolismo , Adenocarcinoma/microbiología , Adenocarcinoma/patología , Adulto , Anciano , Anciano de 80 o más Años , Biomarcadores de Tumor/metabolismo , Femenino , Genotipo , Helicobacter pylori/genética , Humanos , Neoplasias Intestinales/microbiología , Neoplasias Intestinales/patología , Masculino , Persona de Mediana Edad , Proteínas Proto-Oncogénicas c-bcl-2/metabolismo , Estudios Retrospectivos , Neoplasias Gástricas/microbiología , Neoplasias Gástricas/patología , Proteína X Asociada a bcl-2/metabolismoRESUMEN
PURPOSE: To investigate the frequency and the association of vacA alleles, cagA, cagE and virB11 genes of Helicobacter pylori from patients with gastric cancer, considering the clinic histopathological parameters. METHODS: One hundred and one gastric adenocarcinoma tissues were assessed by PCR to detect H. pylori and vacA alleles, cagA, cagE and virB11. RESULTS: The distribution of cases according to the presence of the genes studied showed that the group containing vacA s1m1, cagA, cagE and virB11 H. pylori genes was significantly more frequent, followed by the group with at least one marker on the right side and left of the island. They were also present in the early stages and were the most frequent in nearly all histopathological grades. CONCLUSIONS: This study verified that vacAs1m1 and cag-PAI genes, cagA, cagE and virB11 are important H. pylori markers for gastric cancer development. Also, this study corroborates the importance of cagE and cagA together as cag-PAI marker.
Asunto(s)
Antígenos Bacterianos/genética , Proteínas Bacterianas/genética , Helicobacter pylori/genética , Neoplasias Gástricas/patología , Neoplasias Gástricas/virología , Factores de Virulencia/genética , Adenocarcinoma/genética , Adenocarcinoma/patología , Adenocarcinoma/virología , Adulto , Anciano , Anciano de 80 o más Años , Brasil/epidemiología , ADN Viral/genética , Femenino , Estudios de Seguimiento , Infecciones por Helicobacter/genética , Infecciones por Helicobacter/patología , Infecciones por Helicobacter/virología , Helicobacter pylori/patogenicidad , Humanos , Masculino , Persona de Mediana Edad , Estadificación de Neoplasias , Reacción en Cadena de la Polimerasa , Prevalencia , Pronóstico , Neoplasias Gástricas/epidemiología , Neoplasias Gástricas/genética , Adulto JovenRESUMEN
MTHFR C677T and Helicobacter pylori infection are believed to play critical roles in the DNA methylation process, an epigenetic feature frequently found in gastric cancer. The aim of this study was to verify the associations between the MTHFR C677T polymorphism and the methylation status of three gastric cancer-related genes. The influence of H. pylori strains was also assessed. DNA extracted from 71 gastric tumor samples was available for MTHFR C677T genotyping by PCR-RFLP, promoter methylation identification by MS-PCR and H. pylori detection and posterior subtyping (cagA and vacA genes) by PCR. In the distal tumors, a positive correlation was found between the methylation of CDKN2A and the allele T carriers (r=0.357; p=0.009). Considering the eldest patients (age ≥60 years old), this correlation was even higher (r=0,417; p=0.014). H. pylori infection by highly pathogenic strains (cagA+/vacAs1m1) was also found correlated to promoter methylation of CDKN2A and the allele T carriers in distal tumors (r=0.484; p=0.026). No significant correlation was verified between MTHFR C677T genotype and promoter methylation status when we analyzed the general sample. DNA methylation in CDKN2A associated to the MTHFR 677T carrier is suggested to be a distal tumor characteristic, especially in those 60 years old or older, and it seems to depend on the infection by H. pylori cagA/vacAs1m1 strains.
Asunto(s)
Adenocarcinoma/genética , Metilación de ADN/fisiología , ADN de Neoplasias/fisiología , Infecciones por Helicobacter/complicaciones , Metilenotetrahidrofolato Reductasa (NADPH2)/genética , Polimorfismo Genético/genética , Neoplasias Gástricas/genética , Proteínas Adaptadoras Transductoras de Señales/genética , Adenocarcinoma/fisiopatología , Adulto , Anciano , Anciano de 80 o más Años , Alelos , Inhibidor p16 de la Quinasa Dependiente de Ciclina/genética , Ciclooxigenasa 2/genética , Femenino , Genotipo , Infecciones por Helicobacter/fisiopatología , Helicobacter pylori , Humanos , Masculino , Persona de Mediana Edad , Homólogo 1 de la Proteína MutL , Proteínas Nucleares/genética , Estudios Retrospectivos , Neoplasias Gástricas/fisiopatologíaRESUMEN
Promoter hypermethylation of CDKN2A (p16INK4A protein) is the main mechanism of gene inactivation. However, its association with Helicobacter pylori infection is a controversial issue. Therefore, we examined a series of gastric adenocarcinomas to assess the association between p16INK4A inactivation and H. pylori genotype (vacA, cagA, cagE, virB11 and flaA) according to the location and histological subtype of the tumors. p16INK4A expression and CDKN2A promoter methylation were found in 77 gastric adenocarcinoma samples by immunohistochemistry and methylation-specific PCR, respectively. Helicobacter pylori infection and genotype were determined by PCR. A strong negative correlation between immunostaining and CDKN2A promoter region methylation was found. In diffuse subtype tumors, the inactivation of p16INK4A by promoter methylation was unique in noncardia tumors (p=0.022). In addition, H. pylori-bearing flaA was associated with non-methylation tumors (p=0.008) and H. pylori strain bearing cagA or vacAs1m1 genes but without flaA was associated with methylated tumors (p=0.022 and 0.003, respectively). Inactivation of p16INK4A in intestinal and diffuse subtypes showed distinct carcinogenic pathways, depending on the tumor location. Moreover, the process of methylation of the CDKN2A promoter seems to depend on the H. pylori genotype. The present data suggest that there is a differential influence and relevance of H. pylori genotype in gastric cancer development.
Asunto(s)
Adenocarcinoma/genética , Genes p16 , Infecciones por Helicobacter/genética , Neoplasias Gástricas/genética , Adenocarcinoma/microbiología , Adenocarcinoma/patología , Inhibidor p16 de la Quinasa Dependiente de Ciclina/genética , Metilación de ADN/genética , Femenino , Silenciador del Gen , Infecciones por Helicobacter/microbiología , Infecciones por Helicobacter/patología , Helicobacter pylori/genética , Humanos , Inmunohistoquímica , Masculino , Persona de Mediana Edad , Reacción en Cadena de la Polimerasa , Regiones Promotoras Genéticas/genética , Neoplasias Gástricas/microbiología , Neoplasias Gástricas/patologíaRESUMEN
BACKGROUND: The association between Helicobacter pylori gene diversity and gastric cancer has been poorly reported, although it is one of the important ways to explain the gastric pathogenesis. The aim of this study was to investigate the frequency of cagE and virB11 genes in H. pylori isolated from patients with gastric cancer and to analyze the histology profiles. MATERIALS AND METHODS: The presence of H. pylori and subtypes (cagE and virB11) was detected by PCR from the genomic DNA of 101 patients who had been diagnosed with gastric cancer. The cases were grouped according to the presence/absence of the genes studied and were analyzed in relation to histopathological parameters. RESULTS: H. pylori infection was detected in 94 out of 101 (93.1%) gastric carcinomas. The cases were categorized into the following groups: cagE+/virB11+, cagE+/virB11-, cagE-/virB11+, and cagE-/virB11-. Frequencies were: 50% (47/94) cagE+/virB11+, 3.2% (3/94) cagE+/virB11-, 10.6% (10/94) cagE-/virB11+, and 36.2% (34/94) cagE-/virB11-. Tumors in the gastric antrum were predominant. An exception was the cagE-/virB11- group, in which tumors had a tendency to be located in the gastric cardia; the majority of the cardia tumors (56% (14/25)) were in this group. Intestinal histology type was the most frequent, but the cagE+/virB11- group only had diffuse tumors. H. pyloricagE+/virB11+ occurred most frequently (except at stage III), and was present at all gastric cancer stages. CONCLUSIONS: This study is the first to include a relevant number of gastric cancer cases with H. pylori infection, reporting the frequency and relationship of cagE and virB11 genes and the genesis of this tumor. The presence of these cag pathogenicity island genes shows that they are important factors for the pathogenesis and malignancy of gastric cancer related to H. pylori.
Asunto(s)
Antígenos Bacterianos/genética , Proteínas Bacterianas/genética , Helicobacter pylori/genética , Neoplasias Gástricas/virología , Adulto , Anciano , Anciano de 80 o más Años , ADN Bacteriano/análisis , ADN Bacteriano/aislamiento & purificación , Femenino , Infecciones por Helicobacter/genética , Infecciones por Helicobacter/patología , Infecciones por Helicobacter/virología , Helicobacter pylori/metabolismo , Helicobacter pylori/patogenicidad , Humanos , Masculino , Persona de Mediana Edad , Reacción en Cadena de la Polimerasa/métodos , Neoplasias Gástricas/genética , Neoplasias Gástricas/patología , Virulencia/genética , Adulto JovenRESUMEN
OBJECTIVE: Decreases in p27(KIP1) and C-MYC expression have been associated with Helicobacter pylori infection. Furthermore, C-MYC seems to be a transcriptional repressor of p27(KIP1). Therefore, in a series of gastric adenocarcinomas we studied the association of p27(KIP1) expression with H. pylori genotype (vacA, cagA, cagE and virB11) and the involvement of C-MYC in this process. MATERIAL AND METHODS: Expression of p27(KIP1) and C-MYC was determined by immunohistochemistry in 84 gastric adenocarcinoma samples and H. pylori infection and genotype were determined by polymerase chain reaction. RESULTS: Most p27(KIP1)-negative cases (94.0%) were H. pylori-positive and 44.8% were C-MYC-positive. In the diffuse gastric cancer subtype, p27-negative-C-MYC-positive was the most frequent combination (cluster II), and was associated with the more pathogenic H. pylori strains. Although an association with p27(KIP1) and H. pylori strain was found in the intestinal gastric cancer subtype, negativity for p27(KIP1) and C-MYC markers was the most frequent cluster, followed by cluster II, and both were present, independent of the H. pylori genotype. CONCLUSIONS: Reduced expression of p27(KIP1) was closely linked to H. pylori infection, and was dependent on the more pathogenic strains. Moreover, intestinal and diffuse subtypes showed distinct carcinogenic pathways influenced by H. pylori strains. These data add insight to the differential influence and relevance of H. pylori genotype in gastric cancer development.
Asunto(s)
Adenocarcinoma/genética , Infecciones por Helicobacter/genética , Helicobacter pylori/genética , Helicobacter pylori/patogenicidad , Péptidos y Proteínas de Señalización Intracelular/genética , Neoplasias Gástricas/genética , Adulto , Anciano , Anciano de 80 o más Años , Antígenos Bacterianos/genética , Proteínas Bacterianas/genética , Distribución de Chi-Cuadrado , Inhibidor p27 de las Quinasas Dependientes de la Ciclina , Electroforesis en Gel de Agar , Femenino , Gastrectomía , Genotipo , Humanos , Técnicas para Inmunoenzimas , Masculino , Persona de Mediana Edad , Reacción en Cadena de la Polimerasa , Neoplasias Gástricas/cirugíaRESUMEN
AIM: To investigate the interrelationship between H pylori and Epstein-Barr virus (EBV) infection in the gastric carcinogenesis having in focus the p53 mutation and the c-Myc, Bcl-2 and Bax expression. METHODS: seventy-one gastric carcinoma tissues were assessed by polymerase chain reaction (PCR) for H pylori and in situ hybridization for EBV. c-Myc, Bcl-2 and Bax expression were detected by immunohistochemistry and single-stranded conformational polymorphism (SSCP) for p53 mutation. RESULTS: The positivity rates for H pylori and EBV were 94.4% and 8.45%, respectively. The majority of the cases displayed only the H pylori presence. All EBV positive cases were also H pylori positive. None infectious agent was observed in 5.55% of the cases. The intestinal type tumor was more frequent in the co-infected and non-infected groups. The female predominated in the non-infected group showing statistical significance (70.4% vs 29.6%, P = 0.039). The Bcl-2 was only detected in the group exclusively infected by H pylori. However, c-Myc and Bax were detected in the three groups but with a low frequency in the co-infected group. Mutation of p53 was present in all groups, with the highest frequencies in the H pylori positive groups. CONCLUSION: The frequency of H pylori infection in gastric carcinomas was high. The presented data indicated that gastric carcinogenesis has different pathways depending of the presence of the two investigated infectious agents, suggesting a possible involvement of H pylori with apoptotic process. The low expression of c-Myc and Bax in the EBV-positive groups suggests that EBV may inhibit the expression of these proteins. Nevertheless, p53 mutation shows to be a relevant alteration, independent of both infectious agents.
