RESUMEN

The Wnt/beta-catenin pathway has many key roles in the development of animals, including a conserved and central role in the specification of the primary (antero-posterior) body axis. The posterior expression of Wnt ligands and the anterior expression of secreted Wnt inhibitors are known to be conserved during the larval metamorphosis of tapeworms. However, their downstream signaling components for Wnt/beta-catenin signaling have not been characterized. In this work, we have studied the core components of the beta-catenin destruction complex of the human pathogen Echinococcus multilocularis, the causative agent of alveolar echinococcosis. We focused on two Axin paralogs that are conserved in tapeworms and other flatworm parasites. Despite their divergent sequences, both Axins could robustly interact with one E. multilocularis beta-catenin paralog and limited its accumulation in a heterologous mammalian expression system. Similarly to what has been described in planarians (free-living flatworms), other beta-catenin paralogs showed limited or no interaction with either Axin and are unlikely to function as effectors in Wnt signaling. Additionally, both Axins interacted with three divergent GSK-3 paralogs that are conserved in free-living and parasitic flatworms. Axin paralogs have highly segregated expression patterns along the antero-posterior axis in the tapeworms E. multilocularis and Hymenolepis microstoma, indicating that different beta-catenin destruction complexes may operate in different regions during their larval metamorphosis.

Asunto(s)

Proteína Axina/genética , Complejo de Señalización de la Axina/genética , Echinococcus multilocularis/genética , Glucógeno Sintasa Quinasa 3/genética , Proteínas del Helminto/genética , Hymenolepis/genética , beta Catenina/genética , Secuencia de Aminoácidos , Animales , Proteína Axina/química , Proteína Axina/metabolismo , Complejo de Señalización de la Axina/química , Echinococcus multilocularis/crecimiento & desarrollo , Echinococcus multilocularis/metabolismo , Perfilación de la Expresión Génica , Glucógeno Sintasa Quinasa 3/metabolismo , Proteínas del Helminto/química , Humanos , Hymenolepis/crecimiento & desarrollo , Hymenolepis/metabolismo , Larva/metabolismo , Filogenia , Alineación de Secuencia , beta Catenina/metabolismo

RESUMEN

OBJECTIVE: To evaluate the destruction complex of beta-catenin by the expression of the proteins beta-catetenin, adenomatous polyposis coli, GSK3ß, axin and ubiquitin in colorectal carcinoma and colonic adenoma. METHODS: Tissue samples from 64 patients with colorectal carcinoma and 53 patients with colonic adenoma were analyzed. Tissue microarray blocks and slides were prepared and subjected to immunohistochemistry with polyclonal antibodies in carcinoma, adjacent non-neoplastic mucosa, and adenoma tissues. The immunoreactivity was evaluated by the percentage of positive stained cells and by the intensity assessed through of the stained grade of proteins in the cytoplasm and nucleus of cells. In the statistical analysis, the Spearman correlation coefficient, Student's t, χ2, Mann-Whitney, and McNemar tests, and univariate logistic regression analysis were used. RESULTS: In colorectal carcinoma, the expressions of beta-catenin and adenomatous polyposis coli proteins were significantly higher than in colonic adenomas (p<0.001 and p<0.0001, respectively). The immunoreactivity of GSK3ß, axin 1 and ubiquitin proteins was significantly higher (p=0.03, p=0.039 and p=0.03, respectively) in colorectal carcinoma than in the colonic adenoma and adjacent non-neoplastic mucosa. The immunohistochemistry staining of these proteins did not show significant differences with the clinical and pathological characteristics of colorectal cancer and colonic adenoma. CONCLUSIONS: These results suggest that, in adenomas, the lower expression of the beta-catenin, axin 1 and GSK3ß proteins indicated that the destruction complex of beta-catenin was maintained, while in colorectal carcinoma, the increased expression of beta-catenin, GSK3ß, axin 1, and ubiquitin proteins indicated that the destruction complex of beta-catenin was disrupted. OBJETIVO: Avaliar o complexo de destruição da betacatenina no carcinoma colorretal e no adenoma do colo pela expressão das proteínas betacatenina, adenomatous polyposis coli, GSK3ß, axina e ubiquitina. MÉTODOS: Amostras de tecidos de 64 doentes com carcinoma colorretal e de 53 pacientes com adenoma do colo foram analisadas. Blocos de tecidos foram submetidos ao estudo imuno-histoquímico com anticorpos policlonais nos tecidos do carcinoma, mucosa não neoplásica adjacente e adenoma. A imunorreatividade foi avaliada pela porcentagem de positividade de células coradas e pela intensidade do grau de coloração das proteínas no citoplasma e no núcleo das células. Na análise estatística, foram utilizados o coeficiente de correlação de Spearman, os testes t de Student, χ2, Mann-Whitney e de McNemar, e a análise de regressão logística univariada. RESULTADOS: No carcinoma colorretal, as expressões da betacatenina e da adenomatous polyposis coli foram significativamente maiores do que em adenomas do colo (p<0,001 e p<0,0001, respectivamente). A imunorreatividade das proteínas GSK3ß, axina 1 e ubiquitina foi significativamente maior (p=0,03, p=0,039 e p=0,03, respectivamente) no carcinoma colorretal do que no adenoma e na mucosa não neoplásica adjacente. A coloração imuno-histoquímica dessas proteínas não apresentou diferenças significantes em relação às características clinicopatológicas do câncer colorretal e do adenoma. CONCLUSÕES: Em adenomas, as menores expressões de betacatenina, axina 1 e GSK3ß indicaram que o complexo de destruição da betacatenina estava conservado, enquanto que, no carcinoma colorretal, o aumento das expressões da betacatenina, GSK3ß, 1 axina, e ubiquitina indicaram que o complexo de destruição de betacatenina estava alterado.

Asunto(s)

Adenoma/metabolismo , Complejo de Señalización de la Axina/metabolismo , Carcinoma/metabolismo , Neoplasias del Colon/metabolismo , Proteínas de Neoplasias/metabolismo , Neoplasias del Recto/metabolismo , Adenoma/patología , Poliposis Adenomatosa del Colon/metabolismo , Anciano , Anciano de 80 o más Años , Proteína Axina/metabolismo , Carcinoma/patología , Neoplasias del Colon/patología , Femenino , Glucógeno Sintasa Quinasa 3 beta/metabolismo , Humanos , Inmunohistoquímica , Estudios Longitudinales , Masculino , Persona de Mediana Edad , Neoplasias del Recto/patología , Estudios Retrospectivos , Ubiquitina/metabolismo , Vía de Señalización Wnt , beta Catenina/metabolismo

RESUMEN

ABSTRACT Objective To evaluate the destruction complex of beta-catenin by the expression of the proteins beta-catetenin, adenomatous polyposis coli, GSK3β, axin and ubiquitin in colorectal carcinoma and colonic adenoma. Methods Tissue samples from 64 patients with colorectal carcinoma and 53 patients with colonic adenoma were analyzed. Tissue microarray blocks and slides were prepared and subjected to immunohistochemistry with polyclonal antibodies in carcinoma, adjacent non-neoplastic mucosa, and adenoma tissues. The immunoreactivity was evaluated by the percentage of positive stained cells and by the intensity assessed through of the stained grade of proteins in the cytoplasm and nucleus of cells. In the statistical analysis, the Spearman correlation coefficient, Student’s t, χ2, Mann-Whitney, and McNemar tests, and univariate logistic regression analysis were used. Results In colorectal carcinoma, the expressions of beta-catenin and adenomatous polyposis coli proteins were significantly higher than in colonic adenomas (p<0.001 and p<0.0001, respectively). The immunoreactivity of GSK3β, axin 1 and ubiquitin proteins was significantly higher (p=0.03, p=0.039 and p=0.03, respectively) in colorectal carcinoma than in the colonic adenoma and adjacent non-neoplastic mucosa. The immunohistochemistry staining of these proteins did not show significant differences with the clinical and pathological characteristics of colorectal cancer and colonic adenoma. Conclusions These results suggest that, in adenomas, the lower expression of the beta-catenin, axin 1 and GSK3β proteins indicated that the destruction complex of beta-catenin was maintained, while in colorectal carcinoma, the increased expression of beta-catenin, GSK3β, axin 1, and ubiquitin proteins indicated that the destruction complex of beta-catenin was disrupted.

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RESUMO Objetivo Avaliar o complexo de destruição da betacatenina no carcinoma colorretal e no adenoma do colo pela expressão das proteínas betacatenina, adenomatous polyposis coli, GSK3β, axina e ubiquitina. Métodos Amostras de tecidos de 64 doentes com carcinoma colorretal e de 53 pacientes com adenoma do colo foram analisadas. Blocos de tecidos foram submetidos ao estudo imuno-histoquímico com anticorpos policlonais nos tecidos do carcinoma, mucosa não neoplásica adjacente e adenoma. A imunorreatividade foi avaliada pela porcentagem de positividade de células coradas e pela intensidade do grau de coloração das proteínas no citoplasma e no núcleo das células. Na análise estatística, foram utilizados o coeficiente de correlação de Spearman, os testes t de Student, χ2, Mann-Whitney e de McNemar, e a análise de regressão logística univariada. Resultados No carcinoma colorretal, as expressões da betacatenina e da adenomatous polyposis coli foram significativamente maiores do que em adenomas do colo (p<0,001 e p<0,0001, respectivamente). A imunorreatividade das proteínas GSK3β, axina 1 e ubiquitina foi significativamente maior (p=0,03, p=0,039 e p=0,03, respectivamente) no carcinoma colorretal do que no adenoma e na mucosa não neoplásica adjacente. A coloração imuno-histoquímica dessas proteínas não apresentou diferenças significantes em relação às características clinicopatológicas do câncer colorretal e do adenoma. Conclusões Em adenomas, as menores expressões de betacatenina, axina 1 e GSK3β indicaram que o complexo de destruição da betacatenina estava conservado, enquanto que, no carcinoma colorretal, o aumento das expressões da betacatenina, GSK3β, 1 axina, e ubiquitina indicaram que o complexo de destruição de betacatenina estava alterado.

Asunto(s)

Humanos , Masculino , Femenino , Persona de Mediana Edad , Anciano , Anciano de 80 o más Años , Neoplasias del Recto/metabolismo , Carcinoma/metabolismo , Adenoma/metabolismo , Neoplasias del Colon/metabolismo , Complejo de Señalización de la Axina/metabolismo , Proteínas de Neoplasias/metabolismo , Neoplasias del Recto/patología , Inmunohistoquímica , Carcinoma/patología , Adenoma/patología , Estudios Retrospectivos , Estudios Longitudinales , Neoplasias del Colon/patología , Poliposis Adenomatosa del Colon/metabolismo , Ubiquitina/metabolismo , beta Catenina/metabolismo , Proteína Axina/metabolismo , Vía de Señalización Wnt , Glucógeno Sintasa Quinasa 3 beta/metabolismo

RESUMEN

AIM: The aim of this study was to investigate the association of the rs2240308 and rs1133683 polymorphisms in the AXIN2 gene with colorectal cancer (CRC) in Mexican patients. MATERIALS AND METHODS: Genomic DNAs from 201 CRC patients and 100 healthy blood donors were analyzed for AXIN2 gene polymorphisms by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) methodology. Statistical associations were calculated using the odds ratio (OR) test. RESULTS: The genotype distribution of the rs1133683 polymorphism C > T showed a statistical difference between the two study groups (p = 0.0019). Moreover, OR analyses demonstrated that individuals with either the C/T or T/T genotype have a decreased risk for CRC compared with individuals with the C/C genotype (OR = 0.47, 95% confidence interval [CI] = 0.25-0.86, p = 0.0134 and OR = 0.24, 95% CI = 0.10-0.57, p = 0.005, respectively). This association was also evident in a stratified analysis based on tumor-node-metastasis (TNM) stage. For the rs2240308 polymorphism C > T, the OR analysis showed a significantly increased risk for carriers of the T/T genotype (OR = 2.64, 95% CI = 1.12-6.24, p = 0.0236) and this association was also evident in the stratified analysis by TNM stage. CONCLUSION: Our results indicate the possibility that variations in the AXIN2 gene may play a significant role in promoting or preventing CRC development.

Asunto(s)

Proteína Axina/genética , Neoplasias Colorrectales/genética , Adenocarcinoma/epidemiología , Adenocarcinoma/genética , Adenocarcinoma/metabolismo , Adulto , Alelos , Proteína Axina/metabolismo , Estudios de Casos y Controles , Neoplasias Colorrectales/epidemiología , Neoplasias Colorrectales/metabolismo , Femenino , Frecuencia de los Genes , Estudios de Asociación Genética , Predisposición Genética a la Enfermedad , Humanos , Masculino , México/epidemiología , Persona de Mediana Edad , Polimorfismo de Nucleótido Simple , Regiones Promotoras Genéticas

RESUMEN

Background: In 2007, a Clinical-Case-Portfolio (CCP) was introduced as a new assessment instrument for fourth grade undergraduate medical students. Since then, several changes have been implemented such as reduction on the number of clinical cases, peer review and the introduction of virtual patient to the portfolio. Aim: To describe the virtual patient model incorporated to the CCP and assess the perception of this change and its effects on the performance of undergraduate students. Material and Methods: Virtual patients were implemented based on prototype clinical cases with specific syndromes. Students’ perceptions about CCP before and after the introduction of virtual patients were evaluated using a validated questionnaire that was answered voluntarily and anonymously. Results: Overall perception of CCP significantly improved after the incorporation of virtual patients (97.1 ± 24.9 and 111.3 ± 25.7 points; 57.8 and 66.2% respectively). The same improvements were observed for the domains “Student Learning”, “Organization and Evaluation”, “Teaching Methodology” and “Integration”. In both years, students obtained high grades in CCP evaluations. However CCP grades were not significantly correlated with integrated final grades. Conclusions: The incorporation of virtual patients improved undergraduate students’ perception of CCP.

Asunto(s)

Animales , Ratones , Apoptosis , Proteína Axina/metabolismo , Activación Enzimática , Poli(ADP-Ribosa) Polimerasas/metabolismo , Proteínas Serina-Treonina Quinasas/antagonistas & inhibidores , Adenosina Trifosfato/metabolismo , Factor Inductor de la Apoptosis/genética , Factor Inductor de la Apoptosis/metabolismo , Aurora Quinasas , Línea Celular , Membrana Celular/metabolismo , Membrana Celular/fisiología , Mitocondrias/metabolismo , Inhibidores de Proteínas Quinasas/farmacología , Interferencia de ARN , Imagen de Lapso de Tiempo

RESUMEN

OBJECTIVES: We investigated four components of the Wnt signaling pathway in medulloblastomas. Medulloblastoma is the most common type of malignant pediatric brain tumor, and the Wnt signaling pathway has been shown to be activated in this type of tumor. METHODS: Sixty-one medulloblastoma cases were analyzed for ß-catenin gene (CTNNB1) mutations, ß-catenin protein expression via immunostaining and Wnt signaling pathway-related gene expression. All data were correlated with histological subtypes and patient clinical information. RESULTS: CTNNB1 sequencing analysis revealed that 11 out of 61 medulloblastomas harbored missense mutations in residues 32, 33, 34 and 37, which are located in exon 3. These mutations alter the glycogen synthase kinase-3ß phosphorylation sites, which participate in ß-catenin degradation. No significant differences were observed between mutation status and histological medulloblastoma type, patient age and overall or progression-free survival times. Nuclear ß-catenin accumulation, which was observed in 27.9% of the cases, was not associated with the histological type, CTNNB1 mutation status or tumor cell dissemination. The relative expression levels of genes that code for proteins involved in the Wnt signaling pathway (CTNNB1, APC, AXIN1 and WNT1) were also analyzed, but no significant correlations were found. In addition, large-cell variant medulloblastomas presented lower relative CTNNB1 expression as compared to the other tumor variants. CONCLUSIONS: A small subset of medulloblastomas carry CTNNB1 mutations with consequent nuclear accumulation of ß-catenin. The Wnt signaling pathway plays a role in classic, desmoplastic and extensive nodularity medulloblastoma variants but not in large-cell medulloblastomas.

Asunto(s)

Proteína de la Poliposis Adenomatosa del Colon/análisis , Proteína Axina/análisis , Neoplasias Cerebelosas/patología , Meduloblastoma/patología , beta Catenina/análisis , Proteína de la Poliposis Adenomatosa del Colon/metabolismo , Adulto , Proteína Axina/metabolismo , Neoplasias Cerebelosas/genética , Neoplasias Cerebelosas/metabolismo , Distribución de Chi-Cuadrado , Niño , Supervivencia sin Enfermedad , Femenino , Expresión Génica , Humanos , Masculino , Meduloblastoma/genética , Meduloblastoma/metabolismo , Reacción en Cadena en Tiempo Real de la Polimerasa , Estadísticas no Paramétricas , Vía de Señalización Wnt , beta Catenina/metabolismo

RESUMEN

OBJECTIVES: We investigated four components of the Wnt signaling pathway in medulloblastomas. Medulloblastoma is the most common type of malignant pediatric brain tumor, and the Wnt signaling pathway has been shown to be activated in this type of tumor. METHODS: Sixty-one medulloblastoma cases were analyzed for β-catenin gene (CTNNB1) mutations, β-catenin protein expression via immunostaining and Wnt signaling pathway-related gene expression. All data were correlated with histological subtypes and patient clinical information. RESULTS: CTNNB1 sequencing analysis revealed that 11 out of 61 medulloblastomas harbored missense mutations in residues 32, 33, 34 and 37, which are located in exon 3. These mutations alter the glycogen synthase kinase-3β phosphorylation sites, which participate in β-catenin degradation. No significant differences were observed between mutation status and histological medulloblastoma type, patient age and overall or progression-free survival times. Nuclear β-catenin accumulation, which was observed in 27.9% of the cases, was not associated with the histological type, CTNNB1 mutation status or tumor cell dissemination. The relative expression levels of genes that code for proteins involved in the Wnt signaling pathway (CTNNB1, APC, AXIN1 and WNT1) were also analyzed, but no significant correlations were found. In addition, large-cell variant medulloblastomas presented lower relative CTNNB1 expression as compared to the other tumor variants. CONCLUSIONS: A small subset of medulloblastomas carry CTNNB1 mutations with consequent nuclear accumulation of β-catenin. The Wnt signaling pathway plays a role in classic, desmoplastic and extensive nodularity medulloblastoma variants but not in large-cell medulloblastomas.

Asunto(s)

Adulto , Niño , Femenino , Humanos , Masculino , Proteína de la Poliposis Adenomatosa del Colon/análisis , Proteína Axina/análisis , Neoplasias Cerebelosas/patología , Meduloblastoma/patología , beta Catenina/análisis , Proteína de la Poliposis Adenomatosa del Colon/metabolismo , Proteína Axina/metabolismo , Distribución de Chi-Cuadrado , Neoplasias Cerebelosas/genética , Neoplasias Cerebelosas/metabolismo , Supervivencia sin Enfermedad , Expresión Génica , Meduloblastoma/genética , Meduloblastoma/metabolismo , Reacción en Cadena en Tiempo Real de la Polimerasa , Estadísticas no Paramétricas , Vía de Señalización Wnt , beta Catenina/metabolismo