Oxidative stress with subsequent premutagenic oxidative DNA damage has been implicated in colorectal carcinogenesis. The repair of oxidative DNA damage is initiated by lesion-specific DNA glycosylases (hOGG1, NTH1, MUTYH). The direct evidence of the role of oxidative DNA damage and its repair is proven by hereditary syndromes (MUTYH-associated polyposis, NTHL1-associated tumor syndrome), where germline mutations cause loss-of-function in glycosylases of base excision repair, thus enabling the accumulation of oxidative DNA damage and leading to the adenoma-colorectal cancer transition. Unrepaired oxidative DNA damage often results in G:C>T:A mutations in tumor suppressor genes and proto-oncogenes and widespread occurrence of chromosomal copy-neutral loss of heterozygosity. However, the situation is more complicated in complex and heterogeneous disease, such as sporadic colorectal cancer. Here we summarized our current knowledge of the role of oxidative DNA damage and its repair on the onset, prognosis and treatment of sporadic colorectal cancer. Molecular and histological tumor heterogeneity was considered. Our study has also suggested an additional important source of oxidative DNA damage due to intestinal dysbiosis. The roles of base excision repair glycosylases (hOGG1, MUTYH) in tumor and adjacent mucosa tissues of colorectal cancer patients, particularly in the interplay with other factors (especially microenvironment), deserve further attention. Base excision repair characteristics determined in colorectal cancer tissues reflect, rather, a disease prognosis. Finally, we discuss the role of DNA repair in the treatment of colon cancer, since acquired or inherited defects in DNA repair pathways can be effectively used in therapy.

• Klíčová slova
• DNA repair, base excision repair (BER)glycosylases, colorectal cancer, oxidative DNA damage,
• MeSH
• buněčné mikroprostředí MeSH
• cílená molekulární terapie MeSH
• DNA-glykosylasy metabolismus   MeSH
• kolorektální nádory etiologie   metabolismus   patologie   terapie   MeSH
• lidé MeSH
• náchylnost k nemoci * MeSH
• nádorová transformace buněk genetika   metabolismus   MeSH
• oprava DNA MeSH
• oxidační stres * MeSH
• poškození DNA * MeSH
• střevní sliznice metabolismus   mikrobiologie   patologie   MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• přehledy MeSH
• Názvy látek
• DNA-glykosylasy MeSH

Interindividual differences in DNA repair systems may play a role in modulating the individual risk of developing colorectal cancer. To better ascertain the role of DNA repair gene polymorphisms on colon and rectal cancer risk individually, we evaluated 15,419 single nucleotide polymorphisms (SNPs) within 185 DNA repair genes using GWAS data from the Colon Cancer Family Registry (CCFR) and the Genetics and Epidemiology of Colorectal Cancer Consortium (GECCO), which included 8,178 colon cancer, 2,936 rectum cancer cases and 14,659 controls. Rs1800734 (in MLH1 gene) was associated with colon cancer risk (p-value = 3.5 × 10-6 ) and rs2189517 (in RAD51B) with rectal cancer risk (p-value = 5.7 × 10-6 ). The results had statistical significance close to the Bonferroni corrected p-value of 5.8 × 10-6 . Ninety-four SNPs were significantly associated with colorectal cancer risk after Binomial Sequential Goodness of Fit (BSGoF) procedure and confirmed the relevance of DNA mismatch repair (MMR) and homologous recombination pathways for colon and rectum cancer, respectively. Defects in MMR genes are known to be crucial for familial form of colorectal cancer but our findings suggest that specific genetic variations in MLH1 are important also in the individual predisposition to sporadic colon cancer. Other SNPs associated with the risk of colon cancer (e.g., rs16906252 in MGMT) were found to affect mRNA expression levels in colon transverse and therefore working as possible cis-eQTL suggesting possible mechanisms of carcinogenesis.

• Klíčová slova
• DNA repair, cancer susceptibility, colon cancer, genome-wide association studies, rectal cancer, single nucleotide polymorphisms,
• MeSH
• biologická variabilita populace genetika   MeSH
• DNA modifikační methylasy genetika   MeSH
• DNA vazebné proteiny genetika   MeSH
• dospělí MeSH
• enzymy opravy DNA genetika   MeSH
• genetická predispozice k nemoci * MeSH
• hodnocení rizik MeSH
• jednonukleotidový polymorfismus MeSH
• karcinogeneze genetika   MeSH
• kolon patologie   MeSH
• lidé středního věku MeSH
• lidé MeSH
• mladý dospělý MeSH
• MutL homolog 1 genetika   MeSH
• nádorové supresorové proteiny genetika   MeSH
• nádory rekta genetika   patologie   MeSH
• nádory tračníku genetika   patologie   MeSH
• oprava DNA genetika   MeSH
• registrace statistika a číselné údaje   MeSH
• rektum patologie   MeSH
• senioři MeSH
• studie případů a kontrol MeSH
• Check Tag
• dospělí MeSH
• lidé středního věku MeSH
• lidé MeSH
• mladý dospělý MeSH
• mužské pohlaví MeSH
• senioři MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Research Support, N.I.H., Extramural MeSH
• Názvy látek
• DNA modifikační methylasy MeSH
• DNA vazebné proteiny MeSH
• enzymy opravy DNA MeSH
• MGMT protein, human MeSH Prohlížeč
• MLH1 protein, human MeSH Prohlížeč
• MutL homolog 1 MeSH
• nádorové supresorové proteiny MeSH
• RAD51B protein, human MeSH Prohlížeč

Genetic variations in 3' untranslated regions of target genes may affect microRNA binding, resulting in differential protein expression. microRNAs regulate DNA repair, and single-nucleotide polymorphisms in miRNA binding sites (miRSNPs) may account for interindividual differences in the DNA repair capacity. Our hypothesis is that miRSNPs in relevant DNA repair genes may ultimately affect cancer susceptibility and impact prognosis.In the present study, we analysed the association of polymorphisms in predicted microRNA target sites of double-strand breaks (DSBs) repair genes with colorectal cancer (CRC) risk and clinical outcome. Twenty-one miRSNPs in non-homologous end-joining and homologous recombination pathways were assessed in 1111 cases and 1469 controls. The variant CC genotype of rs2155209 in MRE11A was strongly associated with decreased cancer risk when compared with the other genotypes (OR 0.54, 95% CI 0.38-0.76, p = 0.0004). A reduced expression of the reporter gene was observed for the C allele of this polymorphism by in vitro assay, suggesting a more efficient interaction with potentially binding miRNAs. In colon cancer patients, the rs2155209 CC genotype was associated with shorter survival while the TT genotype of RAD52 rs11226 with longer survival when both compared with their respective more frequent genotypes (HR 1.63, 95% CI 1.06-2.51, p = 0.03 HR 0.60, 95% CI 0.41-0.89, p = 0.01, respectively).miRSNPs in DSB repair genes involved in the maintenance of genomic stability may have a role on CRC susceptibility and clinical outcome.

• Klíčová slova
• 3′UTR polymorphisms, MRE11A, colorectal cancer risk and clinical outcomes, double-strand break repair (DSBR) genes, miRNA binding sites,
• MeSH
• 3' nepřekládaná oblast genetika   MeSH
• DNA opravný a rekombinační protein Rad52 genetika   MeSH
• dospělí MeSH
• genetická predispozice k nemoci MeSH
• genotyp MeSH
• homologní protein MRE11 genetika   MeSH
• jednonukleotidový polymorfismus * MeSH
• kolorektální nádory genetika   patologie   MeSH
• lidé středního věku MeSH
• lidé MeSH
• mikro RNA genetika   MeSH
• míra přežití MeSH
• mladý dospělý MeSH
• nádorové biomarkery genetika   MeSH
• následné studie MeSH
• oprava DNA genetika   MeSH
• prognóza MeSH
• senioři nad 80 let MeSH
• senioři MeSH
• studie případů a kontrol MeSH
• vazebná místa MeSH
• Check Tag
• dospělí MeSH
• lidé středního věku MeSH
• lidé MeSH
• mladý dospělý MeSH
• mužské pohlaví MeSH
• senioři nad 80 let MeSH
• senioři MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• 3' nepřekládaná oblast MeSH
• DNA opravný a rekombinační protein Rad52 MeSH
• homologní protein MRE11 MeSH
• mikro RNA MeSH
• MRE11 protein, human MeSH Prohlížeč
• nádorové biomarkery MeSH
• RAD52 protein, human MeSH Prohlížeč

Variations in the TP53 gene have been suggested to play a role in many cancers, including breast. We previously observed an association between TP53 haplotypes based on four polymorphisms (rs17878362, rs1042522, rs12947788, and rs17884306) and the risk of colorectal and pancreatic cancer. Based on these results, in the present study, we have investigated the same polymorphisms and their haplotypes in 705 breast cancer cases and 611 healthy controls in relation to the disease risk, histopathological features of the tumor and clinical outcomes. In comparison to the most common haplotype A1-G-C-G, all the other identified haplotypes were globally associated with a significantly decreased breast cancer risk (P = 0.006). In particular, the A2-G-C-G haplotype was associated with a marked decreased risk of breast cancer when compared with the common haplotype (P = 0.0001). Moreover, rs1042522 in patients carrying the GC genotype and receiving only the anthracycline-based chemotherapy was associated with both overall and disease-free survival (recessive model for overall survival HR = 0.30 95% CI 0.11-0.80, P = 0.02 and for disease-free survival HR = 0.42 95% CI 0.21-0.84, P = 0.01). Present results suggest common genetic features in the susceptibility to breast and gastrointestinal cancers in respect to TP53 variations. In fact, similar haplotype distributions were observed for breast, colorectal, and pancreatic patients in associations with cancer risk. Rs1042522 polymorphism (even after applying the Dunn-Bonferroni correction for multiple testing) appears to be an independent prognostic marker in breast cancer patients.

• MeSH
• genetická predispozice k nemoci genetika   MeSH
• genotyp MeSH
• geny p53 genetika   MeSH
• haplotypy genetika   MeSH
• jednonukleotidový polymorfismus genetika   MeSH
• lidé středního věku MeSH
• lidé MeSH
• nádory prsu genetika   MeSH
• rizikové faktory MeSH
• senioři nad 80 let MeSH
• senioři MeSH
• studie případů a kontrol MeSH
• Check Tag
• lidé středního věku MeSH
• lidé MeSH
• senioři nad 80 let MeSH
• senioři MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

PURPOSE: Increased levels of vitamin D may protect against colorectal cancer (CRC) development and recurrence. Accumulating epidemiologic evidence suggests these effects may be partly mediated by genetic variants of the vitamin D receptor (VDR) proposed to be associated with altered risk of CRC. We wished to determine if common VDR polymorphisms affected CRC risk in the Czech Republic, a homogenous European population with a high CRC incidence rate. METHODS: Frequencies of the common VDR gene polymorphisms rs2238136, rs1544410 (BsmI), rs7975232 (ApaI), and rs731236 (TaqI) were determined using allele-specific PCR in a case control analysis of a series of 754 CRC patients and 627 patients without malignant disease recruited from centers throughout the Czech Republic. Unconditional logistic regression was used to calculate odds ratios and 95% confidence intervals for the association between these variants and risk of CRC. RESULTS: None of the four polymorphisms tested had any significant effect on CRC risk. No significant differences were observed in susceptibility when the population was stratified by anatomical sub-site, sex, BMI, smoking, alcohol, or presence of polyps. CONCLUSIONS: We conclude that common variation in the VDR gene had little effect on its own on predisposition to sporadic CRC in the Czech population.

• MeSH
• DNA genetika   MeSH
• dospělí MeSH
• kolon metabolismus   MeSH
• kolorektální nádory genetika   MeSH
• lidé středního věku MeSH
• lidé MeSH
• polymerázová řetězová reakce MeSH
• polymorfismus genetický genetika   MeSH
• prognóza MeSH
• receptory kalcitriolu genetika   MeSH
• rektum metabolismus   MeSH
• rizikové faktory MeSH
• senioři nad 80 let MeSH
• senioři MeSH
• studie případů a kontrol MeSH
• vitamin D metabolismus   MeSH
• Check Tag
• dospělí MeSH
• lidé středního věku MeSH
• lidé MeSH
• mužské pohlaví MeSH
• senioři nad 80 let MeSH
• senioři MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• srovnávací studie MeSH
• Geografické názvy
• Česká republika MeSH
• Názvy látek
• DNA MeSH
• receptory kalcitriolu MeSH
• vitamin D MeSH

The Czech Republic has one of the highest incidences of colorectal cancer (CRC) in Europe. To evaluate whether sporadic CRCs in Czech patients have specific mutational profiles we analysed somatic genetic changes in known CRC genes (APC, KRAS, TP53, CTNNB1, MUTYH and BRAF, loss of heterozygosity (LOH) at the APC locus, microsatellite instability (MSI), and methylation of the MLH1 promoter) in 103 tumours from 102 individuals. The most frequently mutated gene was APC (68.9% of tumours), followed by KRAS (31.1%), TP53 (27.2%), BRAF (8.7%) and CTNNB1 (1.9%). Heterozygous germline MUTYH mutations in 2 patients were unlikely to contribute to the development of their CRCs. LOH at the APC locus was found in 34.3% of tumours, MSI in 24.3% and MLH1 methylation in 12.7%. Seven tumours (6.9%) were without any changes in the genes tested. The analysis yielded several findings possibly specific for the Czech cohort. Somatic APC mutations did not cluster in the mutation cluster region (MCR). Tumours with MSI but no MLH1 methylation showed earlier onset and more severe mutational profiles compared to MSI tumours with MLH1 methylation. TP53 mutations were predominantly located outside the hot spots, and transitions were underrepresented. Our analysis supports the observation that germline MUTYH mutations are rare in Czech individuals with sporadic CRCs. Our findings suggest the influence of specific ethnic genetic factors and/or lifestyle and dietary habits typical for the Czech population on the development of these cancers.

• MeSH
• adaptorové proteiny signální transdukční genetika   MeSH
• běloši genetika   MeSH
• beta-katenin genetika   MeSH
• DNA-glykosylasy genetika   MeSH
• dospělí MeSH
• jaderné proteiny genetika   MeSH
• kolorektální nádory genetika   MeSH
• lidé středního věku MeSH
• lidé MeSH
• metylace DNA genetika   MeSH
• mikrosatelitní nestabilita MeSH
• mladiství MeSH
• mladý dospělý MeSH
• MutL homolog 1 MeSH
• nádorový supresorový protein p53 genetika   MeSH
• promotorové oblasti (genetika) genetika   MeSH
• protein familiární adenomatózní polypózy genetika   MeSH
• protoonkogenní proteiny B-Raf genetika   MeSH
• protoonkogenní proteiny p21(ras) MeSH
• protoonkogenní proteiny genetika   MeSH
• Ras proteiny genetika   MeSH
• senioři nad 80 let MeSH
• senioři MeSH
• zárodečné mutace genetika   MeSH
• ztráta heterozygozity genetika   MeSH
• Check Tag
• dospělí MeSH
• lidé středního věku MeSH
• lidé MeSH
• mladiství MeSH
• mladý dospělý MeSH
• mužské pohlaví MeSH
• senioři nad 80 let MeSH
• senioři MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Geografické názvy
• Česká republika MeSH
• Názvy látek
• adaptorové proteiny signální transdukční MeSH
• APC protein, human MeSH Prohlížeč
• beta-katenin MeSH
• BRAF protein, human MeSH Prohlížeč
• CTNNB1 protein, human MeSH Prohlížeč
• DNA-glykosylasy MeSH
• jaderné proteiny MeSH
• KRAS protein, human MeSH Prohlížeč
• MLH1 protein, human MeSH Prohlížeč
• MutL homolog 1 MeSH
• mutY adenine glycosylase MeSH Prohlížeč
• nádorový supresorový protein p53 MeSH
• protein familiární adenomatózní polypózy MeSH
• protoonkogenní proteiny B-Raf MeSH
• protoonkogenní proteiny p21(ras) MeSH
• protoonkogenní proteiny MeSH
• Ras proteiny MeSH