Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 73
Filtrar
1.
Artigo em Inglês | MEDLINE | ID: mdl-33318029

RESUMO

BACKGROUND: Evidence for aspirin's chemopreventative properties on colorectal cancer (CRC) is substantial, but its mechanism of action is not well-understood. We combined a proteomic approach with Mendelian randomization (MR) to identify possible new aspirin targets that decrease CRC risk. METHODS: Human colorectal adenoma cells (RG/C2) were treated with aspirin (24 hours) and a stable isotope labeling with amino acids in cell culture (SILAC) based proteomics approach identified altered protein expression. Protein quantitative trait loci (pQTLs) from INTERVAL (N = 3,301) and expression QTLs (eQTLs) from the eQTLGen Consortium (N = 31,684) were used as genetic proxies for protein and mRNA expression levels. Two-sample MR of mRNA/protein expression on CRC risk was performed using eQTL/pQTL data combined with CRC genetic summary data from the Colon Cancer Family Registry (CCFR), Colorectal Transdisciplinary (CORECT), Genetics and Epidemiology of Colorectal Cancer (GECCO) consortia and UK Biobank (55,168 cases and 65,160 controls). RESULTS: Altered expression was detected for 125/5886 proteins. Of these, aspirin decreased MCM6, RRM2, and ARFIP2 expression, and MR analysis showed that a standard deviation increase in mRNA/protein expression was associated with increased CRC risk (OR: 1.08, 95% CI, 1.03-1.13; OR: 3.33, 95% CI, 2.46-4.50; and OR: 1.15, 95% CI, 1.02-1.29, respectively). CONCLUSIONS: MCM6 and RRM2 are involved in DNA repair whereby reduced expression may lead to increased DNA aberrations and ultimately cancer cell death, whereas ARFIP2 is involved in actin cytoskeletal regulation, indicating a possible role in aspirin's reduction of metastasis. IMPACT: Our approach has shown how laboratory experiments and population-based approaches can combine to identify aspirin-targeted proteins possibly affecting CRC risk.

2.
BMC Med ; 18(1): 396, 2020 12 17.
Artigo em Inglês | MEDLINE | ID: mdl-33327948

RESUMO

BACKGROUND: Higher adiposity increases the risk of colorectal cancer (CRC), but whether this relationship varies by anatomical sub-site or by sex is unclear. Further, the metabolic alterations mediating the effects of adiposity on CRC are not fully understood. METHODS: We examined sex- and site-specific associations of adiposity with CRC risk and whether adiposity-associated metabolites explain the associations of adiposity with CRC. Genetic variants from genome-wide association studies of body mass index (BMI) and waist-to-hip ratio (WHR, unadjusted for BMI; N = 806,810), and 123 metabolites from targeted nuclear magnetic resonance metabolomics (N = 24,925), were used as instruments. Sex-combined and sex-specific Mendelian randomization (MR) was conducted for BMI and WHR with CRC risk (58,221 cases and 67,694 controls in the Genetics and Epidemiology of Colorectal Cancer Consortium, Colorectal Cancer Transdisciplinary Study, and Colon Cancer Family Registry). Sex-combined MR was conducted for BMI and WHR with metabolites, for metabolites with CRC, and for BMI and WHR with CRC adjusted for metabolite classes in multivariable models. RESULTS: In sex-specific MR analyses, higher BMI (per 4.2 kg/m2) was associated with 1.23 (95% confidence interval (CI) = 1.08, 1.38) times higher CRC odds among men (inverse-variance-weighted (IVW) model); among women, higher BMI (per 5.2 kg/m2) was associated with 1.09 (95% CI = 0.97, 1.22) times higher CRC odds. WHR (per 0.07 higher) was more strongly associated with CRC risk among women (IVW OR = 1.25, 95% CI = 1.08, 1.43) than men (IVW OR = 1.05, 95% CI = 0.81, 1.36). BMI or WHR was associated with 104/123 metabolites at false discovery rate-corrected P ≤ 0.05; several metabolites were associated with CRC, but not in directions that were consistent with the mediation of positive adiposity-CRC relations. In multivariable MR analyses, associations of BMI and WHR with CRC were not attenuated following adjustment for representative metabolite classes, e.g., the univariable IVW OR for BMI with CRC was 1.12 (95% CI = 1.00, 1.26), and this became 1.11 (95% CI = 0.99, 1.26) when adjusting for cholesterol in low-density lipoprotein particles. CONCLUSIONS: Our results suggest that higher BMI more greatly raises CRC risk among men, whereas higher WHR more greatly raises CRC risk among women. Adiposity was associated with numerous metabolic alterations, but none of these explained associations between adiposity and CRC. More detailed metabolomic measures are likely needed to clarify the mechanistic pathways.

3.
Gut Pathog ; 12: 46, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-33005238

RESUMO

Fusobacterium nucleatum (Fn) is frequently found in colorectal cancers (CRCs). High loads of Fn DNA are detected in CRC tissues with microsatellite instability-high (MSI-H), or with the CpG island hypermethylation phenotype (CIMP). Fn infection is also associated with the inflammatory tumor microenvironment of CRC. A subtype of CRC exhibits inflammation-associated microsatellite alterations (IAMA), which are characterized by microsatellite instability-low (MSI-L) and/or an elevated level of microsatellite alterations at selected tetra-nucleotide repeats (EMAST). Here we describe two independent CRC cohorts in which heavy or moderate loads of Fn DNA are associated with MSI-H and L/E CRC respectively. We also show evidence that Fn produces factors that induce γ-H2AX, a hallmark of DNA double strand breaks (DSBs), in the infected cells.

4.
Gastroenterology ; 2020 Oct 12.
Artigo em Inglês | MEDLINE | ID: mdl-33058866

RESUMO

BACKGROUND AND AIMS: Susceptibility genes and the underlying mechanisms for the majority of risk loci identified by genome-wide association studies (GWAS) for colorectal cancer (CRC) risk remain largely unknown. We conducted a transcriptome-wide association study (TWAS) to identify putative susceptibility genes. METHODS: Gene-expression prediction models were built using transcriptome and genetic data from the 284 normal transverse colon tissues of European descendants from the Genotype-Tissue Expression (GTEx), and model performance was evaluated using data from The Cancer Genome Atlas (n = 355). We applied the gene-expression prediction models and GWAS data to evaluate associations of genetically predicted gene-expression with CRC risk in 58,131 CRC cases and 67,347 controls of European ancestry. Dual-luciferase reporter assays and knockdown experiments in CRC cells and tumor xenografts were conducted. RESULTS: We identified 25 genes associated with CRC risk at a Bonferroni-corrected threshold of P < 9.1 × 10-6, including genes in 4 novel loci, PYGL (14q22.1), RPL28 (19q13.42), CAPN12 (19q13.2), MYH7B (20q11.22), and MAP1L3CA (20q11.22). In 9 known GWAS-identified loci, we uncovered 9 genes that have not been reported previously, whereas 4 genes remained statistically significant after adjusting for the lead risk variant of the locus. Through colocalization analysis in GWAS loci, we additionally identified 12 putative susceptibility genes that were supported by TWAS analysis at P < .01. We showed that risk allele of the lead risk variant rs1741640 affected the promoter activity of CABLES2. Knockdown experiments confirmed that CABLES2 plays a vital role in colorectal carcinogenesis. CONCLUSIONS: Our study reveals new putative susceptibility genes and provides new insight into the biological mechanisms underlying CRC development.

5.
PLoS Genet ; 16(8): e1008947, 2020 08.
Artigo em Inglês | MEDLINE | ID: mdl-32833970

RESUMO

Genome-wide association studies (GWAS) have successfully identified tens of thousands of genetic variants associated with various phenotypes, but together they explain only a fraction of heritability, suggesting many variants have yet to be discovered. Recently it has been recognized that incorporating functional information of genetic variants can improve power for identifying novel loci. For example, S-PrediXcan and TWAS tested the association of predicted gene expression with phenotypes based on GWAS summary statistics by leveraging the information on genetic regulation of gene expression and found many novel loci. However, as genetic variants may have effects on more than one gene and through different mechanisms, these methods likely only capture part of the total effects of these variants. In this paper, we propose a summary statistics-based mixed effects score test (sMiST) that tests for the total effect of both the effect of the mediator by imputing genetically predicted gene expression, like S-PrediXcan and TWAS, and the direct effects of individual variants. It allows for multiple functional annotations and multiple genetically predicted mediators. It can also perform conditional association analysis while adjusting for other genetic variants (e.g., known loci for the phenotype). Extensive simulation and real data analyses demonstrate that sMiST yields p-values that agree well with those obtained from individual level data but with substantively improved computational speed. Importantly, a broad application of sMiST to GWAS is possible, as only summary statistics of genetic variant associations are required. We apply sMiST to a large-scale GWAS of colorectal cancer using summary statistics from ∼120, 000 study participants and gene expression data from the Genotype-Tissue Expression (GTEx) project. We identify several novel and secondary independent genetic loci.


Assuntos
Neoplasias Colorretais/genética , Predisposição Genética para Doença , Estudo de Associação Genômica Ampla , Locos de Características Quantitativas/genética , Neoplasias Colorretais/patologia , Biologia Computacional , Regulação Neoplásica da Expressão Gênica/genética , Variação Genética/genética , Genótipo , Humanos , Modelos Estatísticos , Fenótipo , Polimorfismo de Nucleotídeo Único/genética
6.
Nat Commun ; 11(1): 597, 2020 01 30.
Artigo em Inglês | MEDLINE | ID: mdl-32001714

RESUMO

Physical activity has been associated with lower risks of breast and colorectal cancer in epidemiological studies; however, it is unknown if these associations are causal or confounded. In two-sample Mendelian randomisation analyses, using summary genetic data from the UK Biobank and GWA consortia, we found that a one standard deviation increment in average acceleration was associated with lower risks of breast cancer (odds ratio [OR]: 0.51, 95% confidence interval [CI]: 0.27 to 0.98, P-value = 0.04) and colorectal cancer (OR: 0.66, 95% CI: 0.48 to 0.90, P-value = 0.01). We found similar magnitude inverse associations for estrogen positive (ER+ve) breast cancer and for colon cancer. Our results support a potentially causal relationship between higher physical activity levels and lower risks of breast cancer and colorectal cancer. Based on these data, the promotion of physical activity is probably an effective strategy in the primary prevention of these commonly diagnosed cancers.


Assuntos
Neoplasias da Mama/genética , Neoplasias Colorretais/genética , Exercício Físico , Predisposição Genética para Doença , Análise da Randomização Mendeliana , Acelerometria , Feminino , Humanos , Razão de Chances , Polimorfismo de Nucleotídeo Único/genética , Fatores de Risco
7.
Clin Gastroenterol Hepatol ; 18(9): 1980-1986, 2020 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31634580

RESUMO

BACKGROUND & AIMS: The prevalence of diverticulosis differs with demographic features of patients, but evidence is limited. Well-defined demographic studies are necessary to understand diverticulosis biology. We estimated the prevalence of diverticulosis among patients of different ages, sexes, and races and ethnicities and calculated odds ratios. DESIGN: Using data from an endoscopic database, we identified 271,181 colonoscopy procedures performed from 2000 through 2012 at 107 sites in the United States. Our analysis included individuals 40 years and older who underwent colonoscopy examination for average-risk screening. The outcome was any reported diverticulosis on colonoscopy. Multivariate analyses were performed using logistic regression to estimate odds ratios (ORs) and 95% CI values, adjusting for confounding variables. RESULTS: The prevalence of diverticulosis increased with age in men and women of all races and ethnicities. Women 40-49 years old had significantly lower odds of any diverticulosis (OR, 0.71; 95% CI, 0.63-0.80) compared with men 40-49 years old, after adjustment. The strength of this association decreased with age. Compared with non-Hispanic white individuals, non-Hispanic black individuals (OR, 0.80; 95% CI, 0.77-0.83) and Asian/Pacific Islanders (OR, 0.38; 95% CI, 0.35-0.41) had lower odds of any diverticulosis. However, non-Hispanic black individuals (OR, 1.53, 95% CI, 1.44-1.62) had increased odds of any proximal diverticulosis, whereas Asian/Pacific Islanders (OR, 3.12; 95% CI, 2.67-3.66) had increased odds of only proximal diverticulosis. CONCLUSIONS: In an analysis of data from 271,181 colonoscopy procedures, diverticulosis was less prevalent in women compared with men in the same age groups, indicating that sex hormones might affect pathogenesis. Differences in the odds of diverticulosis by race and ethnicity indicate a genetic contribution to risk.

8.
Gut ; 69(8): 1460-1471, 2020 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31818908

RESUMO

OBJECTIVE: To provide an understanding of the role of common genetic variations in colorectal cancer (CRC) risk, we report an updated field synopsis and comprehensive assessment of evidence to catalogue all genetic markers for CRC (CRCgene2). DESIGN: We included 869 publications after parallel literature review and extracted data for 1063 polymorphisms in 303 different genes. Meta-analyses were performed for 308 single nucleotide polymorphisms (SNPs) in 158 different genes with at least three independent studies available for analysis. Scottish, Canadian and Spanish data from genome-wide association studies (GWASs) were incorporated for the meta-analyses of 132 SNPs. To assess and classify the credibility of the associations, we applied the Venice criteria and Bayesian False-Discovery Probability (BFDP). Genetic associations classified as 'positive' and 'less-credible positive' were further validated in three large GWAS consortia conducted in populations of European origin. RESULTS: We initially identified 18 independent variants at 16 loci that were classified as 'positive' polymorphisms for their highly credible associations with CRC risk and 59 variants at 49 loci that were classified as 'less-credible positive' SNPs; 72.2% of the 'positive' SNPs were successfully replicated in three large GWASs and the ones that were not replicated were downgraded to 'less-credible' positive (reducing the 'positive' variants to 14 at 11 loci). For the remaining 231 variants, which were previously reported, our meta-analyses found no evidence to support their associations with CRC risk. CONCLUSION: The CRCgene2 database provides an updated list of genetic variants related to CRC risk by using harmonised methods to assess their credibility.

9.
Gastroenterology ; 158(5): 1300-1312.e20, 2020 04.
Artigo em Inglês | MEDLINE | ID: mdl-31884074

RESUMO

BACKGROUND & AIMS: Human studies examining associations between circulating levels of insulin-like growth factor 1 (IGF1) and insulin-like growth factor binding protein 3 (IGFBP3) and colorectal cancer risk have reported inconsistent results. We conducted complementary serologic and Mendelian randomization (MR) analyses to determine whether alterations in circulating levels of IGF1 or IGFBP3 are associated with colorectal cancer development. METHODS: Serum levels of IGF1 were measured in blood samples collected from 397,380 participants from the UK Biobank, from 2006 through 2010. Incident cancer cases and cancer cases recorded first in death certificates were identified through linkage to national cancer and death registries. Complete follow-up was available through March 31, 2016. For the MR analyses, we identified genetic variants associated with circulating levels of IGF1 and IGFBP3. The association of these genetic variants with colorectal cancer was examined with 2-sample MR methods using genome-wide association study consortia data (52,865 cases with colorectal cancer and 46,287 individuals without [controls]) RESULTS: After a median follow-up period of 7.1 years, 2665 cases of colorectal cancer were recorded. In a multivariable-adjusted model, circulating level of IGF1 associated with colorectal cancer risk (hazard ratio per 1 standard deviation increment of IGF1, 1.11; 95% confidence interval [CI] 1.05-1.17). Similar associations were found by sex, follow-up time, and tumor subsite. In the MR analyses, a 1 standard deviation increment in IGF1 level, predicted based on genetic factors, was associated with a higher risk of colorectal cancer risk (odds ratio 1.08; 95% CI 1.03-1.12; P = 3.3 × 10-4). Level of IGFBP3, predicted based on genetic factors, was associated with colorectal cancer risk (odds ratio per 1 standard deviation increment, 1.12; 95% CI 1.06-1.18; P = 4.2 × 10-5). Colorectal cancer risk was associated with only 1 variant in the IGFBP3 gene region (rs11977526), which also associated with anthropometric traits and circulating level of IGF2. CONCLUSIONS: In an analysis of blood samples from almost 400,000 participants in the UK Biobank, we found an association between circulating level of IGF1 and colorectal cancer. Using genetic data from 52,865 cases with colorectal cancer and 46,287 controls, a higher level of IGF1, determined by genetic factors, was associated with colorectal cancer. Further studies are needed to determine how this signaling pathway might contribute to colorectal carcinogenesis.


Assuntos
Biomarcadores Tumorais/sangue , Neoplasias Colorretais/epidemiologia , Proteína 3 de Ligação a Fator de Crescimento Semelhante à Insulina/sangue , Fator de Crescimento Insulin-Like I/análise , Idoso , Biomarcadores Tumorais/genética , Estudos de Casos e Controles , Neoplasias Colorretais/sangue , Neoplasias Colorretais/genética , Feminino , Seguimentos , Humanos , Incidência , Proteína 3 de Ligação a Fator de Crescimento Semelhante à Insulina/genética , Fator de Crescimento Insulin-Like I/genética , Fator de Crescimento Insulin-Like II/análise , Masculino , Análise da Randomização Mendeliana , Pessoa de Meia-Idade , Polimorfismo de Nucleotídeo Único , Sistema de Registros/estatística & dados numéricos , Medição de Risco/métodos , Fatores de Risco , Fatores Sexuais , Reino Unido/epidemiologia
10.
Gastroenterology ; 158(5): 1274-1286.e12, 2020 04.
Artigo em Inglês | MEDLINE | ID: mdl-31866242

RESUMO

BACKGROUND & AIMS: Early-onset colorectal cancer (CRC, in persons younger than 50 years old) is increasing in incidence; yet, in the absence of a family history of CRC, this population lacks harmonized recommendations for prevention. We aimed to determine whether a polygenic risk score (PRS) developed from 95 CRC-associated common genetic risk variants was associated with risk for early-onset CRC. METHODS: We studied risk for CRC associated with a weighted PRS in 12,197 participants younger than 50 years old vs 95,865 participants 50 years or older. PRS was calculated based on single nucleotide polymorphisms associated with CRC in a large-scale genome-wide association study as of January 2019. Participants were pooled from 3 large consortia that provided clinical and genotyping data: the Colon Cancer Family Registry, the Colorectal Transdisciplinary Study, and the Genetics and Epidemiology of Colorectal Cancer Consortium and were all of genetically defined European descent. Findings were replicated in an independent cohort of 72,573 participants. RESULTS: Overall associations with CRC per standard deviation of PRS were significant for early-onset cancer, and were stronger compared with late-onset cancer (P for interaction = .01); when we compared the highest PRS quartile with the lowest, risk increased 3.7-fold for early-onset CRC (95% CI 3.28-4.24) vs 2.9-fold for late-onset CRC (95% CI 2.80-3.04). This association was strongest for participants without a first-degree family history of CRC (P for interaction = 5.61 × 10-5). When we compared the highest with the lowest quartiles in this group, risk increased 4.3-fold for early-onset CRC (95% CI 3.61-5.01) vs 2.9-fold for late-onset CRC (95% CI 2.70-3.00). Sensitivity analyses were consistent with these findings. CONCLUSIONS: In an analysis of associations with CRC per standard deviation of PRS, we found the cumulative burden of CRC-associated common genetic variants to associate with early-onset cancer, and to be more strongly associated with early-onset than late-onset cancer, particularly in the absence of CRC family history. Analyses of PRS, along with environmental and lifestyle risk factors, might identify younger individuals who would benefit from preventive measures.


Assuntos
Neoplasias Colorretais/genética , Predisposição Genética para Doença , Idade de Início , Estudos de Casos e Controles , Estudos de Coortes , Análise Mutacional de DNA , Conjuntos de Dados como Assunto , Feminino , Estudo de Associação Genômica Ampla , Técnicas de Genotipagem , Humanos , Estilo de Vida , Masculino , Anamnese , Pessoa de Meia-Idade , Taxa de Mutação , Polimorfismo de Nucleotídeo Único , Fatores de Risco , Sequenciamento Completo do Genoma
11.
Cancer Med ; 8(5): 2503-2513, 2019 05.
Artigo em Inglês | MEDLINE | ID: mdl-31001917

RESUMO

An association between genetic variants in the vitamin D receptor (VDR) gene and epithelial ovarian cancer (EOC) was previously reported in women of African ancestry (AA). We sought to examine associations between genetic variants in VDR and additional genes from vitamin D biosynthesis and pathway targets (EGFR, UGT1A, UGT2A1/2, UGT2B, CYP3A4/5, CYP2R1, CYP27B1, CYP24A1, CYP11A1, and GC). Genotyping was performed using the custom-designed 533,631 SNP Illumina OncoArray with imputation to the 1,000 Genomes Phase 3 v5 reference set in 755 EOC cases, including 537 high-grade serous (HGSOC), and 1,235 controls. All subjects are of African ancestry (AA). Logistic regression was performed to estimate odds ratios (OR) and 95% confidence intervals (CI). We further evaluated statistical significance of selected SNPs using the Bayesian False Discovery Probability (BFDP). A significant association with EOC was identified in the UGT2A1/2 region for the SNP rs10017134 (per allele OR = 1.4, 95% CI = 1.2-1.7, P = 1.2 × 10-6 , BFDP = 0.02); and an association with HGSOC was identified in the EGFR region for the SNP rs114972508 (per allele OR = 2.3, 95% CI = 1.6-3.4, P = 1.6 × 10-5 , BFDP = 0.29) and in the UGT2A1/2 region again for rs1017134 (per allele OR = 1.4, 95% CI = 1.2-1.7, P = 2.3 × 10-5 , BFDP = 0.23). Genetic variants in the EGFR and UGT2A1/2 may increase susceptibility of EOC in AA women. Future studies to validate these findings are warranted. Alterations in EGFR and UGT2A1/2 could perturb enzyme efficacy, proliferation in ovaries, impact and mark susceptibility to EOC.


Assuntos
Afro-Americanos/genética , Carcinoma Epitelial do Ovário/genética , Glucuronosiltransferase/genética , Neoplasias Ovarianas/genética , Receptores de Calcitriol/genética , Teorema de Bayes , Carcinoma Epitelial do Ovário/metabolismo , Carcinoma Epitelial do Ovário/patologia , Receptores ErbB/genética , Feminino , Estudos de Associação Genética , Humanos , Modelos Logísticos , Pessoa de Meia-Idade , Gradação de Tumores , Neoplasias Ovarianas/metabolismo , Neoplasias Ovarianas/patologia , Polimorfismo de Nucleotídeo Único , Vitamina D/biossíntese
12.
Sci Rep ; 8(1): 9470, 2018 06 21.
Artigo em Inglês | MEDLINE | ID: mdl-29930328

RESUMO

Differences in tumor characteristics might partially account for mortality disparities between African American (AA) and European American (EA) colorectal cancer patients. We evaluated effect modification by race for exposure and patient-outcomes associations with colorectal tumor methylation among 218 AA and 267 EA colorectal cancer cases from the population-based North Carolina Colon Cancer Study. Tumor methylation was assessed in CACNA1G, MLH1, NEUROG1, RUNX3, and SOCS1. We used logistic regression to assess whether associations between several lifestyle factors-intake of fruits, vegetables, folate, and non-steroidal anti-inflammatory drugs-and tumor methylation were modified by race. Proportional hazards models were used to evaluate whether race modified associations between tumor methylation and time to all-cause mortality. Greater fruit consumption was associated with greater odds of high NEUROG1 methylation among EA at methylation cut points of 15-35% (maximum OR 3.44, 95% CI 1.66, 7.13) but not among AA. Higher folate intake was associated with lower odds of high CACNA1G methylation among EAs but not AAs. Tumor methylation was not associated with all-cause mortality for either group. Race might modify associations between lifestyle factors and colorectal tumor methylation, but in this sample did not appear to modify associations between tumor methylation and all-cause mortality.


Assuntos
Adenocarcinoma/genética , Afro-Americanos/estatística & dados numéricos , Neoplasias Colorretais/genética , Metilação de DNA , Grupo com Ancestrais do Continente Europeu/estatística & dados numéricos , Adenocarcinoma/epidemiologia , Adenocarcinoma/etnologia , Afro-Americanos/genética , Idoso , Fatores de Transcrição Hélice-Alça-Hélice Básicos/genética , Canais de Cálcio Tipo T/genética , Neoplasias Colorretais/epidemiologia , Neoplasias Colorretais/etnologia , Subunidade alfa 3 de Fator de Ligação ao Core/genética , Dieta , Grupo com Ancestrais do Continente Europeu/genética , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Mortalidade , Proteína 1 Homóloga a MutL/genética , Proteínas do Tecido Nervoso/genética , Proteína 1 Supressora da Sinalização de Citocina/genética
13.
Sci Rep ; 8(1): 4951, 2018 03 21.
Artigo em Inglês | MEDLINE | ID: mdl-29563543

RESUMO

Colonic diverticula are protrusions of the mucosa through weak areas of the colonic musculature. The etiology of diverticulosis is poorly understood, but could be related to gut bacteria. Using mucosal biopsies from the sigmoid colon of 226 subjects with and 309 subjects without diverticula during first-time screening colonoscopy, we assessed whether individuals with incidental colonic diverticulosis have alternations in the adherent bacterial communities in the sigmoid colon. We found little evidence of substantial associations between the microbial community and diverticulosis among cases and controls. Comparisons of bacterial abundances across all taxonomic levels showed differences for phylum Proteobacteria (p = 0.038) and family Comamonadaceae (p = 0.035). The r-squared values measuring the strength of these associations were very weak, however, with values ~2%. There was a similarly small association between the abundance of each taxa and total diverticula counts. Cases with proximal only diverticula and distal only diverticula likewise showed little difference in overall microbiota profiles. This large study suggests little association between diverticula and the mucosal microbiota overall, or by diverticula number and location. We conclude that the mucosal adherent microbiota community composition is unlikely to play a substantial role in development of diverticulosis.


Assuntos
Colo Sigmoide/microbiologia , Diverticulose Cólica/microbiologia , Microbioma Gastrointestinal/fisiologia , Mucosa Intestinal/microbiologia , Idoso , Idoso de 80 Anos ou mais , Bactérias , Biópsia , Estudos de Casos e Controles , Colo Sigmoide/diagnóstico por imagem , Colo Sigmoide/patologia , Colonoscopia , Comamonadaceae/isolamento & purificação , Comamonadaceae/fisiologia , Diverticulose Cólica/diagnóstico , Diverticulose Cólica/patologia , Feminino , Humanos , Mucosa Intestinal/diagnóstico por imagem , Mucosa Intestinal/patologia , Masculino , Pessoa de Meia-Idade , Proteobactérias/isolamento & purificação , Proteobactérias/fisiologia , Índice de Gravidade de Doença
14.
BMC Cancer ; 18(1): 82, 2018 01 16.
Artigo em Inglês | MEDLINE | ID: mdl-29338703

RESUMO

BACKGROUND: Metastases play a role in about 90% of cancer deaths. Markers of epithelial-mesenchymal transition (EMT) measured in primary tumor cancer cells might provide diagnostic information about the likelihood that cancer cells have detached from the primary tumor. Used together with established diagnostic tests of detachment-lymph node evaluation and radiologic imaging-EMT marker measurements might improve the ability of clinicians to assess the patient's risk of metastatic disease. Translation of EMT markers to clinical use has been hampered by a lack of valid analyses of clinically-informative parameters. Here, we demonstrate a rigorous approach to estimating the sensitivity, specificity, and prediction increment of an EMT marker to assess cancer cell detachment from primary tumors. METHODS: We illustrate the approach using immunohistochemical measurements of the EMT marker E-cadherin in a set of colorectal primary tumors from a population-based prospective cohort in North Carolina. Bayesian latent class analysis was used to estimate sensitivity and specificity in a setting of multiple imperfect diagnostic tests and no gold standard. Risk reclassification analysis was used to assess the extent to which addition of the marker to the panel of established diagnostic tests would improve mortality prediction. We explored how changing the latent class conditional dependence assumptions and definition of marker positivity would impact the results. RESULTS: All diagnostic accuracy and prediction increment statistics varied with the choice of cut point to define marker positivity. When comparing different definitions of marker positivity to each other, numerous trade-offs were observed in terms of sensitivity, specificity, predictive discrimination, and prediction model calibration. We then discussed several implementation considerations and the plausibility of analytic assumptions. CONCLUSIONS: The approaches presented here can be extended to any EMT marker, to most forms of cancer, and to different kinds of EMT marker measurements, such as RNA or gene methylation data. These methods provide valid, clinically-informative assessment of whether and how to use a given EMT marker to refine tumor staging and consequent treatment decisions.


Assuntos
Biomarcadores Tumorais/genética , Caderinas/genética , Neoplasias Colorretais/diagnóstico , Transição Epitelial-Mesenquimal/genética , Adulto , Idoso , Neoplasias Colorretais/diagnóstico por imagem , Neoplasias Colorretais/genética , Neoplasias Colorretais/patologia , Feminino , Regulação Neoplásica da Expressão Gênica , Humanos , Linfonodos/diagnóstico por imagem , Linfonodos/patologia , Masculino , Pessoa de Meia-Idade , Estadiamento de Neoplasias , Fatores de Risco
15.
Am J Perinatol ; 35(1): 24-30, 2018 01.
Artigo em Inglês | MEDLINE | ID: mdl-28750469

RESUMO

OBJECTIVE: To measure maternal gut microbiome biodiversity in pregnancy. MATERIALS AND METHODS: In phase 1, maternal fecal samples were collected by rectal swab in 20 healthy pregnant women (14-28 weeks gestation) to measure bacterial abundance. In phase 2, fecal samples were collected from 31 women at enrollment (<20 weeks gestation, baseline) and at 36 to 39 weeks of gestation (follow-up). We assessed cluster analysis to assess bacterial community profiles at the phylum level longitudinally through pregnancy. DNA was extracted from swabs, followed by PCR of the bacterial 16s rRNA gene and multiplex high-throughput sequencing (Ion Torrent). RESULTS: In phase 1, 16 of 20 samples yielded usable data. White women (n = 10) had greater abundance of Firmicutes (23 ± 0.15 vs. 16% ± 0.75, p = 0.007) and Bacteroidetes (24 ± 0.14 vs. 19% ± 0.68, p = 0.015) compared with non-White women (n = 6). In the 11 paired specimens, Bacteroidetes increased in abundance from baseline to follow-up. Compared with women who gained weight below the median gestational weight gain (GWG, <15.4 kg), those who gained above the median GWG had increased abundance of Bacteroidetes (p = 0.02) and other phyla (p = 0.04). CONCLUSION: Maternal microbiome biodiversity changes as pregnancy progresses and correlates with GWG.


Assuntos
Bacteroidetes/classificação , Biodiversidade , Microbioma Gastrointestinal , Ganho de Peso na Gestação , Análise por Conglomerados , Estudos Transversais , Fezes/microbiologia , Feminino , Trato Gastrointestinal/microbiologia , Idade Gestacional , Sequenciamento de Nucleotídeos em Larga Escala , Humanos , Estudos Longitudinais , Obesidade/microbiologia , Gravidez , RNA Ribossômico 16S/genética
16.
Clin Gastroenterol Hepatol ; 16(6): 884-891.e1, 2018 06.
Artigo em Inglês | MEDLINE | ID: mdl-28603053

RESUMO

BACKGROUND & AIMS: Colonic diverticulosis has been reported to be associated with low-grade mucosal inflammation, possibly leading to chronic gastrointestinal symptoms. However, there is poor evidence for this association. We aimed to determine mucosal inflammation and whether diverticula are associated with chronic gastrointestinal symptoms. We explored whether inflammation was present among symptomatic participants with and without diverticula. METHODS: We analyzed data from a prospective study of 619 patients undergoing a screening colonoscopy from 2013 through 2015 at the University of North Carolina Hospital in Chapel Hill, North Carolina. Among our participants, 255 (41%) had colonic diverticula. Colonic mucosal biopsy specimens were analyzed for levels of interleukin 6 (IL6), IL10, and tumor necrosis factor messenger RNAs by quantitative reverse-transcriptase polymerase chain reaction, and numbers of immune cells (CD4+, CD8+, CD57+, and mast cell tryptase) by immunohistochemistry. Gastrointestinal symptoms were assessed using Rome III criteria. Proportional odds models were used to estimate odds ratios (ORs) and 95% confidence interval (CIs). RESULTS: After adjustment for potential confounders, there was no association between diverticulosis and tumor necrosis factor (OR, 0.85; 95% CI, 0.63-1.16), and no association with CD4+ cells (OR, 1.18; 95% CI, 0.87-1.60), CD8+ cells (OR, 0.97; 95% CI, 0.71-1.32), or CD57+ cells (OR, 0.80; 95% CI, 0.59-1.09). Compared with controls without diverticulosis, biopsy specimens from individuals with diverticulosis were less likely to express the inflammatory cytokine IL6 (OR, 0.59; 95% CI, 0.36-0.96). There was no association between diverticulosis and irritable bowel syndrome (OR, 0.53; 95% CI, 0.26-1.05) or chronic abdominal pain (OR, 0.68; 95% CI, 0.38-1.23). There was no evidence for inflammation in patients with symptoms when patients with vs without diverticulosis were compared. CONCLUSIONS: We found no evidence that colonic diverticulosis is associated with mucosal inflammation or gastrointestinal symptoms. Among patients with symptoms and diverticula, we found no mucosal inflammation.


Assuntos
Colite/etiologia , Colite/patologia , Divertículo do Colo/complicações , Mucosite/etiologia , Mucosite/patologia , Adulto , Idoso , Idoso de 80 Anos ou mais , Biópsia , Colonoscopia , Citocinas/análise , Feminino , Humanos , Imuno-Histoquímica , Masculino , Pessoa de Meia-Idade , North Carolina , Estudos Prospectivos
17.
Int J Cancer ; 140(12): 2728-2733, 2017 06 15.
Artigo em Inglês | MEDLINE | ID: mdl-28295283

RESUMO

Genome-wide association studies (GWAS) in ethnic/racial minority populations can help to fine-map previously identified risk regions or discover new risk loci because of the genetic diversity in these populations. We conducted a GWAS of colorectal cancer (CRC) in 6,597 African Americans (1,894 cases and 4,703 controls) (Stage 1) and followed up the most promising markers in a replication set of 2,041 participants of African descent (891 cases and 1,150 controls) (Stage 2). We identified a novel variant, rs56848936 in the gene SYMPK at 19q13.3, associated with colon cancer risk (odds ratio 0.61 for the risk allele G, p = 2.4 × 10-8 ). The frequency of the G allele was 0.06 in African Americans, compared to <0.01 in Europeans, Asians and Amerindians in the 1000 Genomes project. In addition, a variant previously identified through fine-mapping in this GWAS in the region 19q13.1, rs7252505, was confirmed to be more strongly associated with CRC in the African American replication set than the variant originally reported in Europeans (rs10411210). The association between rs7252505 and CRC was of borderline significance (p = 0.05) in a Hispanic population GWAS with 1,611 CRC cases and 4,330 controls. With the three datasets combined, the odds ratio was 0.84 for the risk allele A (95% confidence interval 0.79-0.89, p = 3.7 × 10-8 ). This study further highlights the importance of conducting GWAS studies in diverse ancestry populations.


Assuntos
Neoplasias do Colo/genética , Predisposição Genética para Doença/genética , Estudo de Associação Genômica Ampla/métodos , Polimorfismo de Nucleotídeo Único , Adulto , Afro-Americanos/genética , Idoso , Alelos , Grupo com Ancestrais do Continente Asiático/genética , Cromossomos Humanos Par 19/genética , Neoplasias do Colo/etnologia , Feminino , Frequência do Gene , Predisposição Genética para Doença/etnologia , Genótipo , Hispano-Americanos/genética , Humanos , Masculino , Pessoa de Meia-Idade , Proteínas Nucleares/genética , Fatores de Risco
18.
Curr Biol ; 27(4): 483-494, 2017 Feb 20.
Artigo em Inglês | MEDLINE | ID: mdl-28162896

RESUMO

SIRT1, the most conserved mammalian NAD+-dependent protein deacetylase, plays a vital role in the regulation of metabolism, stress responses, and genome stability. However, the role of SIRT1 in the multi-step process leading to transformation and/or tumorigenesis, as either a tumor suppressor or tumor promoter, is complex and may be dependent upon the context in which SIRT1 activity is altered, and the role of SIRT1 in tumor metabolism is unknown. Here, we demonstrate that SIRT1 dose-dependently regulates cellular glutamine metabolism and apoptosis, which in turn differentially impact cell proliferation and cancer development. Heterozygous deletion of Sirt1 induces c-Myc expression, enhancing glutamine metabolism and subsequent proliferation, autophagy, stress resistance, and cancer formation. In contrast, homozygous deletion of Sirt1 triggers cellular apoptotic pathways, increases cell death, diminishes autophagy, and reduces cancer formation. Consistent with the observed dose dependence in cells, intestine-specific Sirt1 heterozygous mice have enhanced intestinal tumor formation, whereas intestine-specific Sirt1 homozygous knockout mice have reduced development of colon cancer. Furthermore, SIRT1 reduction, but not deletion, is associated with human colorectal tumors, and colorectal cancer patients with low protein expression of SIRT1 have a poor prognosis. Taken together, our findings indicate that the dose-dependent regulation of tumor metabolism and possibly apoptosis by SIRT1 mechanistically contribute to the observed dual roles of SIRT1 in tumorigenesis. Our study highlights the importance of maintenance of a suitable SIRT1 dosage for metabolic and tissue homeostasis, which will have important implications in SIRT1-small-molecule-activator/inhibitor-based therapeutic strategies for cancers.


Assuntos
Apoptose/genética , Carcinogênese/genética , Proliferação de Células , Neoplasias Colorretais/genética , Glutamina/metabolismo , Haploinsuficiência/genética , Sirtuína 1/genética , Animais , Humanos , Camundongos , Camundongos Knockout , Sirtuína 1/metabolismo
19.
Clin Exp Metastasis ; 33(1): 53-62, 2016 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-26507436

RESUMO

Most cancer deaths are due to metastases. Markers of epithelial-mesenchymal transition (EMT) measured in primary tumor cancer cells could be helpful to assess patient risk of metastatic disease, even among those otherwise diagnosed with local disease. Previous studies of EMT markers and patient outcomes used inconsistent methods and did not compare the clinical impact of different expression cut points for the same marker. Using digital image analysis, we measured the EMT markers Snail and E-cadherin in primary tumor specimens from 190 subjects in tissue microarrays from a population-based prospective cohort of colorectal cancer patients and estimated their associations with time-to-death. After measuring continuous marker expression data, we performed a systematic search for the cut point for each marker with the best model fit between dichotomous marker expression and time-to-death. We also assessed the potential clinical impact of different cut points for the same marker. After dichotomizing expression status at the statistically-optimal cut point, we found that Snail expression was not associated with time-to-death. When measured as a weighted average of tumor cores, low E-cadherin expression was associated with a greater risk of dying within 5 years of surgery than high expression (risk difference = 33 %, 95 % confidence interval 3-62 %). Identifying a clinically-optimal cut point for an EMT marker requires trade-offs between strength and precision of the association with patient outcomes, as well as consideration of the number of patients whose treatments might change based on using the marker at a given cut point.


Assuntos
Biomarcadores Tumorais/análise , Neoplasias Colorretais/patologia , Transição Epitelial-Mesenquimal/fisiologia , Metástase Neoplásica/patologia , Idoso , Caderinas/análise , Neoplasias Colorretais/mortalidade , Feminino , Humanos , Processamento de Imagem Assistida por Computador , Imuno-Histoquímica , Estimativa de Kaplan-Meier , Masculino , Pessoa de Meia-Idade , Modelos de Riscos Proporcionais , Fatores de Risco , Fatores de Transcrição da Família Snail , Análise Serial de Tecidos , Fatores de Transcrição/análise
20.
PLoS One ; 10(12): e0144955, 2015.
Artigo em Inglês | MEDLINE | ID: mdl-26683305

RESUMO

Heterocyclic aromatic amines formed in cooked meat may be an underlying mechanism for the red meat-colorectal cancer (CRC) association. These compounds require bioactivaction by N-acetyltransferase 2 (NAT2). An interaction effect between red meat consumption and NAT2 in increasing CRC risk has been inconsistently reported in whites. We investigated this interaction in two populations in which the high-activity rapid NAT2 phenotype is 10- and 2-fold more common than in whites. We meta-analyzed four studies of Japanese (2,217 cases, 3,788 controls) and three studies of African Americans (527 cases, 4,527 controls). NAT2 phenotype was inferred from an optimized seven-SNP genotyping panel. Processed and total red meat intakes were associated with an increased CRC risk in Japanese and in both ethnic groups combined (P's ≤ 0.002). We observed an interaction between processed meat intake and NAT2 in Japanese (P = 0.04), African Americans (P = 0.02), and in both groups combined (P = 0.006). The association of processed meat with CRC was strongest among individuals with the rapid NAT2 phenotype (combined analysis, OR for highest vs. lowest quartile: 1.62, 95% CI: 1.28-2.05; Ptrend = 8.0×10-5), intermediate among those with the intermediate NAT2 phenotype (1.29, 95% CI: 1.05-1.59; Ptrend = 0.05) and null among those with the slow phenotype (Ptrend = 0.45). A similar interaction was found for NAT2 and total red meat (Pinteraction = 0.03). Our findings support a role for NAT2 in modifying the association between red meat consumption and CRC in Japanese and African Americans.


Assuntos
Afro-Americanos/legislação & jurisprudência , Arilamina N-Acetiltransferase/genética , Grupo com Ancestrais do Continente Asiático/genética , Neoplasias Colorretais/etiologia , Carne Vermelha/efeitos adversos , Idoso , Neoplasias Colorretais/genética , Feminino , Predisposição Genética para Doença , Estudo de Associação Genômica Ampla , Genótipo , Humanos , Japão , Masculino , Pessoa de Meia-Idade , Polimorfismo de Nucleotídeo Único , Fatores de Risco , Estados Unidos/etnologia
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA