Alteraciones genéticas en la vía canónica Wnt/β-catenina en cáncer colorrectal

El objetivo de esta revisión es comprender la complejidad de la vía de señalización canónica Wnt/β-catenina (VSC-WβC) en el cáncer colorrectal (CCR): funcionamiento, principales mutaciones y nuevas moléculas terapéuticas en investigación. Se buscaron los artículos médicos más relevantes del tema en PubMed, Scopus y SciELO. VSC-WβC controla importantes fenómenos biológicos celulares; las alteraciones genéticas de esta vía contribuyen significativamente al CCR. La VSC-WβC se activa por la unión del ligando Wnt con el receptor Frizzled y la proteína relacionada al receptor 5 o 6 de la lipoproteína de baja densidad (LRP5/6); este complejo ternario en la membrana extracelular activa a las quinasas que inducen la fosforilación del dominio intracelular de LRP5/6 e inicia la cascada de señalización celular. La VSC-WβC está alterada en más del 90 % de todos los CCR, y es el gen de la poliposis coli adenomatosa, uno de los componentes con mayores transgresiones en este tipo de cáncer. La VSC-WβC es un blanco importante en la investigación de los nuevos tratamientos del cáncer, en los últimos años; varios inhibidores de la vía se han desarrollado para el tratamiento de CCR (anticuerpos monoclonales, proteínas inhibidoras, pequeñas moléculas selectivas y otras familias innovadoras), la mayoría de ellos en etapas preclínicas. En conclusión, el CCR está asociado con mutaciones en VSC-WβC, cuya activación continua otorga a las células cancerosas propiedades de crecimiento autorrenovables y se asocia con la resistencia al tratamiento del CCR. Existe una activa investigación de nuevas moléculas innovadoras que modulan esta vía de señalización; sin embargo, ninguna ha sido aprobada para uso comercial hasta la fecha.

The goal of this study is to better understand the complexity of the canonical Wnt/β-catenin (C-WNT) signaling pathway in colorectal cancer (CRC): how it works, its key mutations and the novel therapeutic compounds under development. PubMed, Scopus and SciELO were used to find the most relevant medical literature on the issue. The C-WNT signaling pathway regulates essential cellular biological processes: genetic changes in this pathway are significant contributors to CRC. The Wnt ligand binding to the Frizzled receptor and low-density lipoprotein receptor-related protein 5 or 6 (LRP5/6) stimulates the C-WNT signaling pathway; this extracellular membrane ternary complex activates kinases that promote phosphorylation of the intracellular domain of LRP5/6 and starts the cell signaling cascade. The C-WNT signaling pathway is changed in more than 90 % of all CRCs, with the adenomatous polyposis coli gene showing the great majority of mutations in this type of cancer. In recent years, the C-WNT signaling pathway has been an important target for researching new cancer treatments; various inhibitors of the pathway (monoclonal antibodies, inhibitory proteins, selective small compounds and other novel families) have been developed for the treatment of CRC, being the majority of them still in preclinical phases. In conclusion, CRC is related to mutations in the C-WNT signaling pathway, whose persistent activation provides cancer cells with self-renewing growth capabilities and is linked to treatment resistance in CRC. There is active research on novel and innovative compounds that affect this signaling pathway; however, none has received commercial approval so far.

Relationship between APC gene 3'-untranslated region rs1804197 polymorphism and colorectal cancer susceptibility / 国际肿瘤学杂志

Objective To explore the relationship between the rs18004197 polymorphism in the 3'-untranslated region of adenomatous polyposis coli (APC) gene and colorectal cancer susceptibility.Methods Firstly,we collected the peripheral venous blood of 573 colorectal cancer cases and 588 controls,and then extracted DNA from blood samples,genotyped rs1804197 polymorphism using real-time PCR and assessed its association with the susceptibility of colorectal cancer.Results There were 387 CC (67.5％),153 AC (26.7％) and 33 AA (5.8％) genotypes in the colorectal cancer cases.In the control group,there were 427 CC (72.6％),144 AC (24.5％) and 17 AA (2.9％) genotypes.The AA genotype odds ratio (OR =2.14,95％ CI:1.17-3.91,P =0.011) and the A allele frequency (P =0.011) were significant difference in case and control groups.Further subgroup analysis showed that the differences of the frequency distribution in the male (P =0.048) and non-drinking (P =0.020) groups were statistically significant.In the male group,the risk of colorectal cancer was increased by 0.41 (OR =1.41,95％ CI:1.01-1.98) for individuals bearing the A allele.In the non-drinking group,the risk of colorectal cancer was increased by 0.22 (OR =1.22,95％ CI:0.91-1.64) for individuals bearing the A allele,but the result was not statistically significant.Conclusion The rs18004197 polymorphism in the 3'-untranslated region of APC gene is related to the susceptibility of colorectal cancer.The AA genotype may increase the susceptibility of colorectal cancer.

The destruction complex of beta-catenin in colorectal carcinoma and colonic adenoma / O complexo destruidor de betacatenina no carcinoma colorretal e no adenoma cólico

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.

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.

Identificação de mutações nos genes APC e MUTYH em famílias com polipose adenomatosa intestinal / Mutational screening of APC and MUTYH genes in families with adenomatous polyposis

Atualmente, pacientes com múltiplos adenomas colorretais são avaliados para mutações germinativas em dois genes, APC e MUTYH. Pacientes com mutações em APC apresentam Polipose Adenomatosa Familiar Clássica ou Atenuada (FAP/AFAP), enquanto que pacientes portadores de mutações bialélicas em MUTYH apresentam Polipose Associada ao MUTYH (MAP). O espectro das mutações em APC e MUTYH, assim como as correlações genótipo-fenótipo nestas síndromes, apresentam importante impacto clínico e podem ser distintas em cada população, tornando necessária a obtenção de dados genéticos e clínicos de diferentes populações. Além disso, cerca de 10-15% dos pacientes com polipose não apresentam mutações nesses genes, o que sugere a existência de outros genes de predisposição ainda desconhecidos. Assim, os objetivos deste estudo foram caracterizar mutações germinativas nos genes APC e MUTYH em pacientes Brasileiros com polipose, além de identificar novos genes associados com a síndrome através de sequenciamento de exoma dos pacientes negativos. No total, 23 pacientes não relacionados foram avaliados para mutações pontuais na região codificante dos genes APC e MUTYH através de sequenciamento capilar, e para rearranjos genômicos nos mesmos genes por meio de MLPA (Multiplex Ligation-Dependent Probe Amplification), arrays de hibridação genômica comparativa (CGH-array), e PCR duplex quantitativo. Este último método de avaliação do número de cópias genômicas foi desenvolvido e validado no presente estudo. Foram identificados 21 pacientes mutados nesta coorte (91%) - 6 pacientes apresentaram mutações patogênicas em MUTYH, 14 apresentaram mutações patogênicas em APC e um paciente foi portador de uma nova variante missense de significado clínico desconhecido em APC (p.Val1789Leu); seis mutações foram descritas pela primeira vez neste trabalho. Em um destes pacientes identificamos a primeira grande deleção genômica descrita no gene MUTYH. Correlações genótipo-fenótipo dos dados...

Patients with multiple colorectal adenomas are currently screened for germline mutations in two genes, APC and MUTYH. APC-mutated patients present classic or attenuated familial adenomatous polyposis (FAP/ AFAP), while patients carrying biallelic MUTYH mutations exhibit MUTYH-associated polyposis (MAP). The spectrum of APC and MUTYH mutations as well as the genotype-phenotype correlations in polyposis syndromes present clinical impact and can be population specific, making important to obtain genetic and clinical data from different populations. Furthermore, up to 10-15% of polyposis patients do not harbor mutations in these genes, suggesting that other yet unknown polyposis-predisposing genes could exist. Thus, the aim of this study was to characterize germline mutations in APC and MUTYH genes in Brazilian polyposis and to investigate novel susceptibility genes by exome sequencing of negative patients. At total, 23 unrelated polyposis patients were screened for APC/MUTYH point mutations through DNA capillary sequencing, and for APC and MUTYH genomic rearrangements through MLPA (multiplex ligation-dependent probe amplification), array-comparative genomic hybridization, and duplex quantitative PCR. This last gene dosage method was developed and validated in this study. We identified 21 mutated patients in this cohort (91%) – 6 patients carried MUTYH pathogenic mutations, 14 carried APC pathogenic mutations and one carried a novel APC missense variant of unknown clinical significance (p.Val1789Leu); six mutations were described for the first time in this series. One of these patients harbored the first large genomic deletion identified in MUTYH gene...

Study on the correlation between methylation of APC genes and expression in pancreatic cancer / 中华检验医学杂志

Objective To investigate the effect of methylation of the APC gene on expression and the correlation with clinical data in pancreatic cancer.Methods Sixty postoperative tissue samples with pancreatic cancer were collected in the First Affiliated Hospital of Zhengzhou University from August 2010 to January 2011,20 benign pancreatic disease tissues were collected as control groups.APC promoter methylation and gene expression levels were detected by Methylation Specific PCR (MSP),Real Time PCR (RT-PCR) and Western blot in 60 pancreatic carcinoma,42 metastasis and 20 benign pancreatic disease tissues,then analyze the relation between methylation of the APC gene and the clinical data.Results APC promoter methlation was observed 48.53％,46.67％ and 1.16％ in pancreatic carcinoma,metastasis and benign pancreatic disease tissue,respectively.Methylation of APC in pancreatic carcinoma and metastasis increased significantly compared with control tissues (x2 =12.903,14.402; P ＜ 0.05).There were no statistically significant differences of APC expression in these tissues (P ＞ 0.05).There was a significant correlation between methylation of APC and clinicopathological stage (x2 =6.801,P ＜ 0.05),but no correlation with gender,age,tumor size,histological grade and metastasis (x2 =0.727,1.311,0.372,0.148,0.017 ; P ＞ 0.05).Conclusion The methylation of APC gene is closely related with pancreatic carcinoma inogenesis and the clinicopathological stage,but do not effect the expression of APC in tissues.

Mutación homocigota en la línea germinal del gen MUTYH en una paciente chilena con poliposis adenomatosa familiar / Homozygous germline mutation in MUTYH gene in familial adenomatous polyposis

Recently, MUTYH mutations have been reported to predispose to the development of polyposis. However, polyposis caused by mutations in MUTYH has been characterized as an autosomal recessive hereditary disease, different from the autosomal dominant pattern observed in polyposis caused by APC mutations. We report a 41-year-old female consulting for anemia. Colonoscopy detected multiple sessile polyps and a cecal carcinoma. The patient was operated and in the surgical piece, the tumor invaded serosa and there was lymph node involvement. Approximately 100 polyps were found. The patient received 5-fluorouracil, as adjuvant therapy. The patient had a sister (of a total of 12 brothers) with a colorectal carcinoma. The genetic study identified a homozygous mutation of the MUTYH gene, called c.340T > C, that produces an amino acid change of tyrosine for histidine called p.Y114H. The sister with colorectal cancer was a heterozygous carrier of this mutation.

Expressions of APC,bcl-2 and c-met in gastric cancer and its precancerous lesion and their significances / 吉林大学学报(医学版)

Objective To investigate the role of the expressions of APC,bcl-2 and c-met gene in the progress of gastric cancer and their significances in the diagnosis of early gastric cancer.Methods The immunohistochemical technique was used to detect the expressions of APC,bcl-2 and c-met gene in 30 cases of human gastric carcinoma(GC),30 cases of intestinal metaplasia(IM),30 dysplasia(Dys) gastric mucosa,10 gastric adenoma(GA) and 20 normal gastric mucosa.Results ①The positive expression rates of APC in GC,IM,Dys and GA(53.3%,67.7% and 53.3%,respectively) were significantly lower than those in normal gastric mucosa(90.0%,P

HELICOBACTER PYLORI INFECTION IS NOT RELATED TO hMLH1 AND APC MUTATION AND PROMOTER METHYLATION IN GASTRIC CANCER / 解放军医学杂志

0 05). APC mutation was correlated with intestinal type of gastric cancer ( P 0 05). APC mutation was detected in all MSI Low or MSS, while no mutation was found in MSI H. Conclusion hMLH1 mutation and promoter methylation are involved in MSI pathway and APC mutation is involved in LOH pathway in gastric cancer. H pylori infection is not related to hMLH1, APC mutation and promoter methylation in gastric cancer.