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BACKGROUND: The incidence of early-onset colorectal cancer (EOCRC; diagnosed <50 years of age) is rising globally; however, the causes underlying this trend are largely unknown. CRC has strong genetic and environmental determinants, yet common genetic variants and causal modifiable risk factors underlying EOCRC are unknown. We conducted the first EOCRC-specific genome-wide association study (GWAS) and Mendelian randomization (MR) analyses to explore germline genetic and causal modifiable risk factors associated with EOCRC. PATIENTS AND METHODS: We conducted a GWAS meta-analysis of 6176 EOCRC cases and 65 829 controls from the Genetics and Epidemiology of Colorectal Cancer Consortium (GECCO), the Colorectal Transdisciplinary Study (CORECT), the Colon Cancer Family Registry (CCFR), and the UK Biobank. We then used the EOCRC GWAS to investigate 28 modifiable risk factors using two-sample MR. RESULTS: We found two novel risk loci for EOCRC at 1p34.1 and 4p15.33, which were not previously associated with CRC risk. We identified a deleterious coding variant (rs36053993, G396D) at polyposis-associated DNA repair gene MUTYH (odds ratio 1.80, 95% confidence interval 1.47-2.22) but show that most of the common genetic susceptibility was from noncoding signals enriched in epigenetic markers present in gastrointestinal tract cells. We identified new EOCRC-susceptibility genes, and in addition to pathways such as transforming growth factor (TGF) ß, suppressor of Mothers Against Decapentaplegic (SMAD), bone morphogenetic protein (BMP) and phosphatidylinositol kinase (PI3K) signaling, our study highlights a role for insulin signaling and immune/infection-related pathways in EOCRC. In our MR analyses, we found novel evidence of probable causal associations for higher levels of body size and metabolic factors-such as body fat percentage, waist circumference, waist-to-hip ratio, basal metabolic rate, and fasting insulin-higher alcohol drinking, and lower education attainment with increased EOCRC risk. CONCLUSIONS: Our novel findings indicate inherited susceptibility to EOCRC and suggest modifiable lifestyle and metabolic targets that could also be used to risk-stratify individuals for personalized screening strategies or other interventions.
Assuntos
Neoplasias Colorretais , Predisposição Genética para Doença , Estudo de Associação Genômica Ampla , Análise da Randomização Mendeliana , Adulto , Feminino , Humanos , Masculino , Idade de Início , Estudos de Casos e Controles , Neoplasias Colorretais/genética , Neoplasias Colorretais/epidemiologia , Polimorfismo de Nucleotídeo Único , Fatores de RiscoRESUMO
Pleiotropic variants (i.e., genetic polymorphisms influencing more than one phenotype) are often associated with cancer risk. A scan of pleiotropic variants was successfully conducted ten years ago in relation to pancreatic ductal adenocarcinoma susceptibility. However, in the last decade, genetic association studies performed on several human traits have greatly increased the number of known pleiotropic variants. Based on the hypothesis that variants already associated with a least one trait have a higher probability of association with other traits, 61,052 variants reported to be associated by at least one genome wide association study (GWAS) with at least one human trait were tested in the present study consisting of two phases (discovery and validation), comprising a total of 16,055 pancreatic ductal adenocarcinoma (PDAC) cases and 212,149 controls. The meta-analysis of the two phases showed two loci (10q21.1-rs4948550 (P=6.52×10-5) and 7q36.3-rs288762 (P=3.03×10-5) potentially associated with PDAC risk. 10q21.1-rs4948550 shows a high degree of pleiotropy and it is also associated with colorectal cancer risk while 7q36.3-rs288762 is situated 28,558 base pairs upstream of the Sonic Hedgehog (SHH) gene, which is involved in the cell differentiation process and PDAC etiopathogenesis. In conclusion, none of the single nucleotide polymorphisms (SNPs) showed a formally statistically significant association after correction for multiple testing. However, given their pleiotropic nature and association with various human traits including colorectal cancer, the two SNPs showing the best associations with PDAC risk merit further investigation through fine mapping and ad hoc functional studies.
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OBJECTIVES: Colorectal cancer (CRC) remains a major health burden. Although screening is recommended and considered beneficial, further data on its positive effects are needed for worldwide implementation. STUDY DESIGN: The aim of our national multicentre prospective observational study was to reveal and document clinicopathological differences in CRC diagnosed by screening and presented by disease symptoms as well as assess the efficiency of the screening programme in the Czech Republic. METHODS: Between March 2013 and September 2015, a total of 265 patients were enrolled in 12 gastroenterology centres across the Czech Republic. Patients were divided into screening and symptomatic groups and compared for pathology status and clinical characteristics. Screening was defined as a primary screening colonoscopy or a colonoscopy after a positive faecal occult blood test in an average-risk population. RESULTS: The distribution of CRC stages was significantly (statistically and clinically) favourable in the screening group (predominance of stages 0, I and II) compared with the non-screening group (P < 0.001). The presence of distant and local metastases was significantly less frequent in the screening group than in the symptomatic group (P < 0.001). Patients in the screening group had a higher probability of radical surgery (R0) than those diagnosed based on symptoms (P < 0.001). Systemic palliative treatment was indicated in two patients in the screening group compared with 23 patients in the non-screening group (P = 0.018). CONCLUSION: CRC diagnosed by screening disclosed less advanced clinicopathological characteristics and results in patients with a higher probability of radical surgery (R0) than diagnoses established based on symptoms, with subsequent management differing accordingly between both groups. These results advocate the implementation of a suitable worldwide screening programme.
Assuntos
Neoplasias Colorretais/epidemiologia , Detecção Precoce de Câncer , Programas de Rastreamento/métodos , Idoso , Colonoscopia , Neoplasias Colorretais/diagnóstico , República Tcheca/epidemiologia , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Sangue Oculto , Estudos Prospectivos , Fatores de Risco , Índice de Gravidade de DoençaRESUMO
BACKGROUND: This study addresses involvement of major 5-fluorouracil (5-FU) pathway genes in the prognosis of colorectal carcinoma patients. METHODS: Testing set and two validation sets comprising paired tumor and adjacent mucosa tissue samples from 151 patients were used for transcript profiling of 15 5-FU pathway genes by quantitative real-time PCR and DNA methylation profiling by high resolution melting analysis. Intratumoral molecular profiles were correlated with clinical data of patients. Protein levels of two most relevant candidate markers were assessed by immunoblotting. RESULTS: Downregulation of DPYD and upregulation of PPAT, UMPS, RRM2, and SLC29A1 transcripts were found in tumors compared to adjacent mucosa in testing and validation sets of patients. Low RRM2 transcript level significantly associated with poor response to the first-line palliative 5-FU-based chemotherapy in the testing set and with poor disease-free interval of patients in the validation set irrespective of 5-FU treatment. UPP2 was strongly methylated while its transcript absent in both tumors and adjacent mucosa. DPYS methylation level was significantly higher in tumor tissues compared to adjacent mucosa samples. Low intratumoral level of UPB1 methylation was prognostic for poor disease-free interval of the patients (P = 0.0002). The rest of the studied 5-FU genes were not methylated in tumors or adjacent mucosa. CONCLUSIONS: The observed overexpression of several 5-FU activating genes and DPYD downregulation deduce that chemotherapy naïve colorectal tumors share favorable gene expression profile for 5-FU therapy. Low RRM2 transcript and UPB1 methylation levels present separate poor prognosis factors for colorectal carcinoma patients and should be further investigated.
Assuntos
Antimetabólitos Antineoplásicos/farmacologia , Neoplasias Colorretais/genética , Fluoruracila/farmacologia , Perfilação da Expressão Gênica , Regulação Neoplásica da Expressão Gênica/efeitos dos fármacos , Transcriptoma , Idoso , Idoso de 80 Anos ou mais , Neoplasias Colorretais/metabolismo , Neoplasias Colorretais/mortalidade , Neoplasias Colorretais/patologia , Ilhas de CpG , Metilação de DNA , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Gradação de Tumores , Estadiamento de Neoplasias , Regiões Promotoras Genéticas , Ribonucleosídeo Difosfato Redutase/genética , Ribonucleosídeo Difosfato Redutase/metabolismo , Transdução de Sinais/efeitos dos fármacosRESUMO
BACKGROUND: Colorectal cancer (CRC) remains a major health burden with an incidence of 1.3 million new cases worldwide and a mortality of almost 8.5%. It is the 2nd most common cancer in women (1st breast carcinoma) and 3rd most common in men (1st lung carcinoma, 2nd prostate carcinoma). CRC alongside breast, lung, prostate and stomach cancer is in the top five most common cancers in men and women worldwide. There are still more than 50% of CRC patients diagnosed with advanced disease (stage III and IV) in the Czech Republic. Genetically, CRC is a very heterogeneous disease with many factors playing key roles in pathogenesis. There are two types of CRC, hereditary with an incidence of between 5% and 10% with APC (FAP, aFAP) or MMR (HNPCC) genes affected, and sporadic colorectal cancer with an incidence of 90-95% with a lot of mutations in variable genes that accumulate during pathogenesis (APC, KRAS, MMR, microRNA, CIMP etc.). Knowledge of the molecular pathogenesis of CRC (hereditary, sporadic) is crucial for treatment, assessment of risk, prognosis, and patient follow-up. CONCLUSION: This article summarizes the molecular pathogenesis of sporadic and hereditary CRC.
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Neoplasias Colorretais/genética , Proteína da Polipose Adenomatosa do Colo/genética , Neoplasias Colorretais/epidemiologia , Neoplasias Colorretais/terapia , Receptor DCC , Reparo de Erro de Pareamento de DNA/genética , Humanos , MicroRNAs/genética , Prognóstico , Proteínas Proto-Oncogênicas p21(ras)/genética , Receptores de Superfície Celular/genética , Medição de Risco , Proteínas Smad/genética , Proteína Supressora de Tumor p53/genética , Proteínas Supressoras de Tumor/genéticaRESUMO
A functionally normal TP53 is essential to protect organisms from developing cancer. Somatic mutations in the gene represent one of the highest recurring perturbations in human tumours, including colorectal cancer (CRC). However, the variegated phenotype of wide spectrum of somatic mutations in TP53 and the complexity of the disease prevent a straight interpretation of the mutational analysis in tumours. In addition to the presence of somatic mutations, polymorphic features of the gene may also contribute to alteration of the normal TP53 functioning and variants, mainly in the form of single nucleotide polymorphisms, can be expected to impact susceptibility to sporadic CRC. In the present study, we reviewed the potential role of alterations in the TP53 gene, both somatic mutations and inherited sequence variations, in predisposition to CRC and in the prognosis and response to therapy. The available data from association studies have mostly shown contradictory outcomes. The majority of the studies were based on limited sample sizes and focussed on a limited number of polymorphisms, with main being the rs1042522 (Arg72Pro). Thus far, there is no possible generalisation of the role of TP53 as also a predictor of therapeutic response and prognosis. The effects of TP53, and its abnormalities, on the response of tumours to cytotoxic drugs, radiation and chemoradiation are complex. However, from studies it is emerging that the inherited genetics of TP53 pathway components could be utilised to further define patient populations in their abilities to induce p53 activity in response to either DNA damaging or p53-targeted therapies.
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Neoplasias Colorretais/genética , Predisposição Genética para Doença , Mutação/genética , Polimorfismo Genético/genética , Proteína Supressora de Tumor p53/genética , Humanos , PrognósticoRESUMO
Worldwide, colorectal cancer (CRC) is the third most common cancer, with the highest mortality rates occurring in Central Europe. The use of chemotherapy to treat CRC is limited by the inter-individual variability in drug response and the development of cancer cell resistance. ATP-binding cassette (ABC) transporters play a crucial role in the development of resistance by the efflux of anticancer agents outside of cancer cells. The aim of this study was to explore transcript levels of all human ABCs in tumours and non-neoplastic control tissues from CRC patients collected before the first line of treatment by 5-fluorouracil (5-FU)-containing regimen. The prognostic potential of ABCs was evaluated by the correlation of transcript levels with clinical factors. Relations between transcript levels of ABCs in tumours and chemotherapy efficacy were also addressed. The transcript profile of all known human ABCs was assessed using real-time polymerase chain reaction with a relative standard curve. The majority of the studied ABCs were down-regulated or unchanged between tumours and control tissues. ABCA12, ABCA13, ABCB6, ABCC1, ABCC2 and ABCE1 were up-regulated in tumours versus control tissues. Transcript levels of ABCA12, ABCC7 and ABCC8 increased in direction from colon to rectum. Additionally, transcript levels of ABCB9, ABCB11, ABCG5 and ABCG8 followed the reverse significant trend, i.e. a decrease in direction from colon to rectum. The transcript level of ABCC10 in tumours correlated with the grade (P = 0.01). Transcript levels of ABCC6, ABCC11, ABCF1 and ABCF2 were significantly lower in non-responders to palliative chemotherapy in comparison with responders. The disease-free interval of patients treated by adjuvant chemotherapy was significantly shorter in patients with low transcript levels of ABCA7, ABCA13, ABCB4, ABCC11 and ABCD4. In conclusion, ABCC11 may be a promising candidate marker for a validation study on 5-FU therapy outcome.
Assuntos
Transportadores de Cassetes de Ligação de ATP/genética , Neoplasias Colorretais/genética , Idoso , Antineoplásicos/uso terapêutico , Estudos de Casos e Controles , Quimioterapia Adjuvante , Colo/metabolismo , Neoplasias Colorretais/tratamento farmacológico , Neoplasias Colorretais/mortalidade , Progressão da Doença , Feminino , Regulação Neoplásica da Expressão Gênica , Humanos , Masculino , Pessoa de Meia-Idade , Proteína 2 Associada à Farmacorresistência Múltipla , Metástase Neoplásica , Projetos Piloto , Prognóstico , RNA Mensageiro/genética , Reação em Cadeia da Polimerase em Tempo Real , Reto/metabolismo , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Taxa de SobrevidaRESUMO
AIM: Ornithine decarboxylase (ODC) is a modifier of adenomatous polyposis coli-dependent tumourigenesis. The G316 > A polymorphism in intron 1 of the ODC gene lies between two myc-binding domains and alters the expression of the gene to affect polyamine metabolism. This variant may be associated with recurrence of colorectal adenoma. We examined whether this variant also modified the susceptibility to sporadic colorectal cancer (CRC). METHOD: The G316 > A variant was analysed in a large (n = 754) CRC case-controlled series of hospital patient volunteers (n = 627) in the Czech Republic, and the relationship with cancer risk was estimated by conditional logistic regression. RESULTS: After adjusting for age and sex, G316 > A was associated with no decrease in CRC risk for either heterozygotes [odds ratio 0.98, 95% confidence interval (CI) 0.77-1.23] or rare allele homozygotes (odds ratio 0.92, 95% CI 0.61-1.37). CONCLUSION: The G316 > A functional variant in the ODC gene is unlikely to make much impact on reducing CRC risk regardless of the reduction in risk found for the recurrence of colorectal adenoma.
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Carcinoma/genética , Neoplasias do Colo/genética , Ornitina Descarboxilase/genética , Polimorfismo de Nucleotídeo Único , Neoplasias Retais/genética , Adulto , Idoso , Idoso de 80 Anos ou mais , Estudos de Casos e Controles , República Tcheca , Feminino , Genótipo , Humanos , Íntrons , Modelos Logísticos , Masculino , Pessoa de Meia-IdadeRESUMO
Huntington's disease (HD), as well as Parkinson's disease and Alzheimer's disease, belong to a group of neurodegenerative diseases characterized by common features, such as the progressive loss of neurons and the presence of pathogenic forms of misfolded protein aggregates. A quality control system such as autophagy is crucial for the clearance of protein aggregates and dysfunctional organelles and thus essential for the maintenance of neuronal homeostasis. The constant high energy demand of neuronal tissue links neurodegeneration to mitochondria. Inefficient removal of damaged mitochondria is thought to contribute to the pathogenesis of neurodegenerative diseases such as HD. In addition, direct involvement of the huntingtin protein in the autophagic machinery has been described. In this review, we focus on mitophagy, a selective form of autophagy responsible for mitochondrial turnover. We also discuss the relevance of pharmacological regulation of mitophagy in the future therapeutic approach to neurodegenerations, including HD.
Assuntos
Proteína Huntingtina/metabolismo , Doença de Huntington/metabolismo , Mitocôndrias/metabolismo , Mitofagia/fisiologia , Agregados Proteicos/fisiologia , Animais , Produtos Biológicos/uso terapêutico , Humanos , Proteína Huntingtina/genética , Doença de Huntington/tratamento farmacológico , Doença de Huntington/genética , Doença de Huntington/patologia , Mitocôndrias/genética , Mitocôndrias/patologia , Neurônios/metabolismo , Neurônios/patologia , Fármacos Neuroprotetores/uso terapêuticoRESUMO
Pancreatic carcinoma is the fourth leading cause of cancer-related deaths in the Czech Republic, with only a minimum of patients surviving 5 years. The aetiology and molecular pathogenesis are still weakly understood. TP53 has a fundamental role in cell cycle and apoptosis and is frequently mutated in solid tumours, including pancreatic cancer. Based on the assumption that genetic variation may affect susceptibility to cancer development, the role of TP53 polymorphisms in modulating the risk of pancreatic cancer may be of major importance. We investigated four selected polymorphisms in TP53 (rs17878362:A(1)>A(2), rs1042522:G>C, rs12947788:C>T and rs17884306:G>A) in association with pancreatic cancer risk in a case-control study, including 240 cases and controls (for a total of 1827 individuals) from the Czech Republic. Carriers of the variant C allele of rs1042522 polymorphism were at an increased risk of pancreatic cancer [odds ratio (OR) 1.73; 95% confidence interval (CI) 1.26-2.39; P = 0.001]. Haplotype analysis showed that in comparison with the most common haplotype (A(1)GCG), the A(2)CCG haplotype was associated with an increased risk (OR 1.39; 95% CI 1.02-1.88; P = 0.034) and the A(1)CCG with a reduced risk (OR 0.30; 95% CI 0.12-0.76; P = 0.011) for this cancer. These results reflect previous findings of a recent association study, where haplotypes constructed on the same TP53 variants were associated with colorectal cancer risk [Polakova et al. (2009) Genotype and haplotype analysis of cell cycle genes in sporadic colorectal cancer in the Czech Republic. Hum. Mutat., 30, 661-668.]. Genetic variation in TP53 may contribute, alone or in concert with other risk factors, to modify the inherited susceptibility to pancreatic cancer, as well as to other gastrointestinal cancers.
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Genes p53 , Haplótipos , Neoplasias Pancreáticas/genética , Adulto , Idoso , Idoso de 80 Anos ou mais , República Tcheca , Feminino , Predisposição Genética para Doença , Genótipo , Humanos , Masculino , Pessoa de Meia-Idade , RiscoRESUMO
It is now recognised that a part of the inherited risk of colorectal cancer (CRC) can be explained by the co-inheritance of low-penetrance genetic variants. The accumulated experience to date in identifying these variants has served to highlight difficulties in conducting statistically and methodologically rigorous studies and follow-up analyses. The COGENT (COlorectal cancer GENeTics) consortium includes 20 research groups in Europe, Australia, the Americas, China and Japan. The overarching goal of COGENT is to identify and characterise low-penetrance susceptibility variants for CRC through association-based analyses. In this study, we review the rationale for identifying low-penetrance variants for CRC and our proposed strategy for establishing COGENT.
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Neoplasias Colorretais/genética , Polimorfismo Genético , Predisposição Genética para Doença , Humanos , Penetrância , Prognóstico , Risco , Fatores de RiscoRESUMO
BACKGROUND: Restless legs syndrome (RLS) is associated with common variants in three intronic and intergenic regions in MEIS1, BTBD9, and MAP2K5/LBXCOR1 on chromosomes 2p, 6p and 15q. METHODS: Our study investigated these variants in 649 RLS patients and 1230 controls from the Czech Republic (290 cases and 450 controls), Austria (269 cases and 611 controls) and Finland (90 cases and 169 controls). Ten single nucleotide polymorphisms (SNPs) within the three genomic regions were selected according to the results of previous genome-wide scans. Samples were genotyped using Sequenom platforms. RESULTS: We replicated associations for all loci in the combined samples set (rs2300478 in MEIS1, p = 1.26 x 10(-5), odds ratio (OR) = 1.47, rs3923809 in BTBD9, p = 4.11 x 10(-5), OR = 1.58 and rs6494696 in MAP2K5/LBXCOR1, p = 0.04764, OR = 1.27). Analysing only familial cases against all controls, all three loci were significantly associated. Using sporadic cases only, we could confirm the association only with BTBD9. CONCLUSION: Our study shows that variants in these three loci confer consistent disease risks in patients of European descent. Among the known loci, BTBD9 seems to be the most consistent in its effect on RLS across populations and is also most independent of familial clustering.
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Polimorfismo de Nucleotídeo Único , Síndrome das Pernas Inquietas/genética , Adulto , Idoso , Áustria , Proteínas Correpressoras , República Tcheca , Feminino , Finlândia , Frequência do Gene , Predisposição Genética para Doença , Genótipo , Proteínas de Homeodomínio/genética , Humanos , MAP Quinase Quinase 5/genética , Masculino , Pessoa de Meia-Idade , Proteína Meis1 , Proteínas de Neoplasias/genética , Proteínas do Tecido Nervoso , Razão de Chances , Proteínas Repressoras/genética , Fatores de Transcrição/genéticaRESUMO
The question of susceptibility to squamous cell carcinoma of head and neck (SCCHN) in the environmental context was addressed by analysis of functional polymorphisms in enzymes metabolizing smoke constituents and/or alcohol (CYP2A13, CYP1B1, EPHX1, NQO1, GSTM1, GSTP1, GSTT1, ADH1B and ADH1C). Case-control study of 122 age- and sex-matched pairs of subjects was performed using so far unexplored Central European Slavic population with high level of tobacco and alcohol abuse. Age-, gender-, smoking- and alcohol-adjusted logistic regression failed to demonstrate any significant association of the analyzed polymorphisms with the SCCHN risk. When interactions between potential modifiers of effect, i.e. smoking and alcohol were tested, drinkers seemed to be at lower risk than nondrinkers when carrying the heterozygous genotype Ile/Val in codon 432 of CYP1B1 (OR=0.42; 95% CI=0.21-0.83; p=0.013 vs. OR=1.02; 95% CI=0.34-2.94; p=0.977). Similarly, drinkers were at lower risk than nondrinkers when carrying the heterozygous genotype Pro/Ser in codon 187 of NQO1 (OR=0.41; 95% CI=0.19-0.88; p=0.022 vs. OR=0.96; 95% CI=0.29-3.12; p=0.948). More interestingly, drinkers carrying the rare homozygous genotype Val/Val in codon 350 of ADH1C were at significantly higher risk than nondrinkers carrying this genotype (OR=4.01; 95% CI=1.61-10.01; p=0.003 vs. OR=0.93; 95% CI=0.25-3.57; p=0.919). This result confirmed findings of previously published studies. Smoking did not significantly modify the effect of genotypes. Our data thus demonstrate that genetic susceptibility to SCCHN shall be further followed on populations with different genetic background and lifestyle.
Assuntos
Carcinoma de Células Escamosas/enzimologia , Carcinoma de Células Escamosas/genética , Neoplasias de Cabeça e Pescoço/enzimologia , Neoplasias de Cabeça e Pescoço/genética , Polimorfismo Genético , Adulto , Idoso , Idoso de 80 Anos ou mais , Álcool Desidrogenase/genética , Hidrocarboneto de Aril Hidroxilases , Carcinoma de Células Escamosas/etnologia , Carcinoma de Células Escamosas/etiologia , Estudos de Casos e Controles , Citocromo P-450 CYP1B1 , Sistema Enzimático do Citocromo P-450/genética , Europa (Continente)/epidemiologia , Feminino , Genótipo , Neoplasias de Cabeça e Pescoço/etnologia , Neoplasias de Cabeça e Pescoço/etiologia , Humanos , Modelos Logísticos , Masculino , Pessoa de Meia-Idade , NAD(P)H Desidrogenase (Quinona)/genética , Risco , FumarRESUMO
The Czech Republic has one of the highest incidences of colorectal cancer (CRC) in the world. To assess the role of genetic variants on the disease, we genotyped polymorphisms in the TP53 (rs17878362:A(1)>A(2), rs1042522:G>C, rs12947788:C>T, and rs17884306:G>A), CDKN1A (rs1801270:C>A and rs1059234:C>T), and CDKN2A (rs3731249:G>A, rs11515:C>G, and rs3088440:C>T) genes in 614 hospital-based CRC cases and 614 matched controls from the country. Despite the tendency toward differential distribution of variant allele frequencies for some polymorphisms, none was significantly associated with CRC risk. We observed differential distribution of major haplotypes arising from four polymorphisms in the TP53 gene between cases and controls (global P<0.0001). The two most common haplotypes, A(1)GCG and A(2)CCG, were present in 81% of the cases compared to 71% of the controls. In comparison to the most common haplotype (A(1)GCG), the haplotype A(2)CCG was associated with an increased risk (odds ratio [OR], 1.40; 95% confidence interval [CI], 1.07-1.82), while the four other haplotypes A(1)CCG (OR, 0.60; 95% CI, 0.45-0.79), A(2)GCG (OR, 0.53; 95% CI, 0.35-0.81), A(1)GTG (OR, 0.31; 95% CI, 0.15-0.64), and A(1)GCA (OR, 0.19; 95% CI, 0.07-0.51) were associated with a decreased risk. The effect of haplotypes in the TP53 gene was similar in colon (global P<0.0001) and rectal cancers (P=0.006). No association with the disease was observed with haplotypes of the CDKN1A and CDKN2A polymorphisms. The results from this study suggest that prevalent haplotypes within the TP53 gene may modulate CRC risks in the population.
Assuntos
Proteínas de Ciclo Celular/genética , Neoplasias Colorretais/genética , Haplótipos , Adulto , Alelos , Estudos de Casos e Controles , Neoplasias Colorretais/patologia , Inibidor p16 de Quinase Dependente de Ciclina/genética , Inibidor de Quinase Dependente de Ciclina p21/genética , República Tcheca , Feminino , Frequência do Gene , Predisposição Genética para Doença , Genótipo , Humanos , Modelos Logísticos , Masculino , Razão de Chances , Polimorfismo de Nucleotídeo Único , Fatores de Risco , Proteína Supressora de Tumor p53/genéticaRESUMO
Colorectal cancer represents a complex disease where susceptibility may be influenced by genetic polymorphisms in the DNA repair system. In the present study we investigated the role of nine single nucleotide polymorphisms in eight DNA repair genes on the risk of colorectal cancer in a hospital-based case-control population (532 cases and 532 sex- and age-matched controls). Data analysis showed that the variant allele homozygotes for the Asn148Glu polymorphism in the APE1 gene were at a statistically non-significant increased risk of colorectal cancer. The risk was more pronounced for colon cancer (odds ratio, OR: 1.50; 95% confidence interval, CI: 1.01-2.22; p=0.05). The data stratification showed increased risk of colorectal cancer in the age group 64-86 years in both individuals heterozygous (OR: 1.79; 95% CI: 1.04-3.07; p=0.04) and homozygous (OR: 2.57; 95% CI: 1.30-5.06; p=0.007) for the variant allele of the APE1 Asn148Glu polymorphism. Smokers homozygous for the variant allele of the hOGG1 Ser326Cys polymorphism showed increased risk of colorectal cancer (OR: 4.17; 95% CI: 1.17-15.54; p=0.03). The analysis of binary genotype combinations showed increased colorectal cancer risk in individuals simultaneously homozygous for the variant alleles of APE1 Asn148Glu and hOGG1 Ser326Cys (OR: 6.37; 95% CI: 1.40-29.02; p=0.02). Considering the subtle effect of the DNA repair polymorphisms on the risk of colorectal cancer, exploration of gene-gene and gene-environmental interactions with a large sample size with sufficient statistical power are recommended.
Assuntos
Neoplasias Colorretais/genética , Reparo do DNA , Polimorfismo de Nucleotídeo Único , Adulto , Fatores Etários , Idoso , Idoso de 80 Anos ou mais , Estudos de Casos e Controles , República Tcheca , Feminino , Predisposição Genética para Doença , Genótipo , Humanos , Masculino , Pessoa de Meia-Idade , Risco , Fatores de Risco , FumarRESUMO
The Czech Republic presents one of the highest incidences of colorectal cancer in the world. We genotyped 10 single nucleotide polymorphisms in five DNA mismatch repair genes in 614 colorectal cancer cases and 614 matched controls from this country. The carriers of T-allele of the hMSH6-556G>T polymorphism were at increased risk of colorectal cancer (OR 1.29; 95% CI 1.02-1.62). The stratification of data showed that risk associated with the polymorphism was confined to rectal cancer (OR 1.42; 95% CI 1.03-1.95). The A-allele of the Ex1-145G>A polymorphism in the hMSH6 gene was associated with a decreased risk of colorectal cancer (OR 0.76; 95% CI 0.60-0.98). The C-allele of the IVS4-101G>C polymorphism in hMSH6 was associated with an increased risk of colon cancer (OR 1.34; 95% CI 1.03-1.74). The carriers of the variant allele for the polymorphism IVS9-1406C>T in hMLH1 exhibited a decreased risk of rectal cancer (OR 0.71; 95% CI 0.51-0.98). We observed a differential distribution of haplotypes based on three hMSH6 polymorphisms (-556G>T-Ex1-145G>A-IVS4-101G>C) in the cases and controls (global P=0.02). The TAG haplotype was associated with a decreased risk of colorectal cancer (OR 0.74; 95% CI 0.59-0.92), whereas the most frequent haplotype GGG was associated with increased risk of rectal cancer (OR 1.32; 95% CI 1.05-1.65). However, multiple hypotheses testing diminishes a statistical significance of above associations. Our data suggest a limited role for the investigated individual variants in mismatch repair genes for the susceptibility to the disease. The haplotypes covering hMSH6 gene may, however, be involved in risk modulation in this population.
Assuntos
Carcinoma/genética , Neoplasias Colorretais/genética , Reparo de Erro de Pareamento de DNA/genética , Haplótipos/fisiologia , Polimorfismo de Nucleotídeo Único/fisiologia , Adulto , Idoso , Idoso de 80 Anos ou mais , Estudos de Casos e Controles , Feminino , Frequência do Gene , Predisposição Genética para Doença , Humanos , Desequilíbrio de Ligação , Masculino , Pessoa de Meia-Idade , Fatores de RiscoRESUMO
Colorectal cancer (CRC) therapy using conventional chemotherapeutics represents a considerable burden for the patient's organism because of high toxicity while the response is relatively low. Our review summarizes the findings about natural compounds as chemoprotective agents for decreasing risk of CRC. It also identifies natural compounds which possess anti-tumor effects of various characteristics, mainly in vitro on colorectal cell lines or in vivo studies on experimental models, but also in a few clinical trials. Many of natural compounds suppress proliferation by inducing cell cycle arrest or induce apoptosis of CRC cells resulting in the inhibition of tumor growth. A novel employment of natural substances is a so-called combination therapy - administration of two or more substances - conventional chemotherapeutics and a natural compound or more natural compounds at a time. Some natural compounds may sensitize to conventional cytotoxic therapy, reinforce the drug effective concentration, intensify the combined effect of both administered therapeutics or exert cytotoxic effects specifically on tumor cells. Moreover, combined therapy by targeting multiple signaling pathways, uses various mechanisms to reduce the development of resistance to antitumor drugs. The desired effect could be to diminish burden on the patient's organism by replacing part of the dose of a conventional chemotherapeutic with a natural substance with a defined effect. Many natural compounds are well tolerated by the patients and do not cause toxic effects even at high doses. Interaction of conventional chemotherapeutics with natural compounds introduces a new aspect in the research and therapy of cancer. It could be a promising approach to potentially achieve improvements, while minimizing of adverse effects associated with conventional chemotherapy.
Assuntos
Protocolos de Quimioterapia Combinada Antineoplásica/farmacologia , Produtos Biológicos/farmacologia , Neoplasias Colorretais/tratamento farmacológico , Animais , Protocolos de Quimioterapia Combinada Antineoplásica/química , Produtos Biológicos/química , Produtos Biológicos/isolamento & purificação , Proliferação de Células/efeitos dos fármacos , Neoplasias Colorretais/patologia , Relação Dose-Resposta a Droga , Humanos , Estrutura Molecular , Relação Estrutura-AtividadeRESUMO
Genotoxic effects related to exposure to styrene have been a matter of investigation for many years by employing markers of exposure, effect and susceptibility. The role of individual DNA-repair capacity in response to exposure to styrene may explain the controversial results so far obtained, but it is still scarcely explored. In the present study, we measured capacity to repair oxidative DNA damage in cell extracts obtained from 24 lamination workers occupationally exposed to styrene and 15 unexposed controls. The capacity to repair oxidative DNA damage was determined by use of a modified comet assay, as follows: HeLa cells, pre-treated with photosensitizer and irradiated with a halogen lamp in order to induce 7,8-dihydroxy-8-oxoguanine, were incubated with cell extracts from mononuclear leukocytes of each subject. The level of strand breaks reflects the removal of 7,8-dihydroxy-8-oxoguanine from substrate DNA by the enzymatic extract. In styrene-exposed subjects a moderate, non-significant increase in oxidative DNA repair was observed. Stratification for sex and smoking habit showed that unexposed males (P=0.010) and unexposed smokers (P=0.037) exhibited higher DNA-repair rates. The repair capacity did not correlate with parameters of styrene exposure and biomarkers of genotoxic effects (DNA strand breaks, N1-styrene-adenine DNA adducts, chromosomal aberrations and mutant frequencies at the HPRT locus). Significantly higher levels of DNA-repair capacity were observed in carriers of GSTM1-plus, compared to those with a deletion in GSTM1. The DNA-repair capacity was significantly lower in individuals with variant Gln/Gln genotype in XRCC1 Arg399Gln than in those with heterozygous Arg/Gln and wild-type Arg/Arg genotypes. Significantly lower repair capacity was also found in individuals with the wild-type Lys/Lys genotype in XPC Lys939Gln as compared with those homozygous for the Gln/Gln variant genotype.
Assuntos
Biomarcadores/análise , Reparo do DNA , Guanina/análogos & derivados , Exposição Ocupacional , Estireno/toxicidade , Adulto , Ensaio Cometa , Dano ao DNA , Suscetibilidade a Doenças , Feminino , Genótipo , Guanina/metabolismo , Células HeLa , Humanos , Masculino , Pessoa de Meia-Idade , Testes de Mutagenicidade , Polimorfismo GenéticoRESUMO
The mismatch repair gene MLH1 is a gene encoding the mismatch repair protein MutL homolog 1 (MLH1), important for repairing mutations generated during DNA replication. MLH1 absence has been observed in human gastrointestinal tumours as well as tumours of the female reproductive tract. We describe the functions of MLH 1 in cell cycle regulation and DNA mismatch repair. In this sense we discuss foriegn knowledges, in which the canine colon adencarcinoma is less frequently diagnosed in Czech and Slovak regions. We briefly described a molecular mechanism of evolution of MSI+ and MSI- colorectal carcinomas in human, and this was confronted with the current opinion of canine colon adenocarcinomas. We suppose that canine colon adenocarcinomas may occur in higher frequency, but they are underdiagnosed in the clinical veterinary practice. At the end, we describe two cases of dogs diagnosed with colorectal adenocarcinoma. The authors propose the centralized collection of colon adenocarcinoma samples from dogs, in one reference veterinary histopathological laboratory, which would analyse mismatch repair proteins.
Assuntos
Adenocarcinoma/veterinária , Neoplasias do Colo/veterinária , Doenças do Cão/genética , Proteína 1 Homóloga a MutL/genética , Adenocarcinoma/diagnóstico , Adenocarcinoma/genética , Animais , Colo/patologia , Neoplasias do Colo/diagnóstico , Neoplasias do Colo/genética , Doenças do Cão/patologia , Cães , MasculinoRESUMO
1-SO-adenine DNA adducts, DNA single-strand breaks (SBs), chromosomal aberrations (CAs), mutant frequency (MF) at the HPRT gene, and immune parameters (hematological and of humoral immunity) were studied in styrene-exposed human subjects and controls. Results were correlated with genetic polymorphisms in DNA repair genes (XPD, exon 23, XPG, exon 15, XPC, exon 15, XRCC1, exon 10, XRCC3, exon 7) and cell cycle gene cyclin D1. Results for biomarkers of genotoxicity after stratification for the different DNA repair genetic polymorphisms showed that the polymorphism in exon 23 of the XPD gene modulates levels of chromosomal and DNA damage, HPRT MF, and moderately affects DNA adduct levels. The highest levels of biomarkers were associated with the wild-type homozygous AA genotype. The exposed individuals with the wild-type GG genotype for XRCC1 gene exhibited the lowest CA frequencies, compared to those with an A allele (P < 0.05). Cyclin D1 polymorphism seems to modulate the number of leukocytes and lymphocytes in the analyzed subjects. The number of eosinophiles was positively associated with XPD variant C allele and negatively with XRCC1 variant A allele (P < 0.05) and XPC variant C allele (P < 0.05). Immunoglobulin IgA was positively associated with an XRCC3 variant T allele (P < 0.01) and negatively with XPC variant C allele (P < 0.05). Both C3- and C4-complement components were lower in individuals with XRCC3 CT (P < 0.05) and TT genotypes (P < 0.01). Adhesion molecules sL-selectin and sICAM-1 were associated with XPC genotype (P < 0.05). Individual susceptibility may be reflected in genotoxic and immunotoxic responses to environmental and occupational exposures to xenobiotics.