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Colorectal cancer (CRC) is one of the most common malignant tumors. One of the factors increasing the risk of its occurrence may be the reduced efficiency of repairing DNA damage, both nuclear and mitochondrial. The main mechanism for repairing oxidative damage is the BER system (in mitochondria mtBER), whose key proteins NEIL1, NEIL2, OGG1, MUTYH, APE1 and LIG3 obtain full efficiency only at the appropriate level of acetylation. Sirtuin 3 is a key protein for mitochondrial homeostasis, regulating a number of metabolic processes related mainly to the control of the level of reactive oxygen species. Because Sirt3 possesses acetylase activity, it can modulate the level of activity of mtBER proteins by their deacetylation. The conducted study showed that the tested proteins NEIL1, NEIL2, OGG1, MUTYH, APE1 and LIG3 are the substrate for the enzymatic deacetylation activity of Sirt3, which may lead to modulation of the risk of CRC, and in cancer cells may be a potential therapeutic target enhancing the action of cytostatic drugs.

Introduction: Colorectal cancer is the second most common cancer worldwide. DNA double strand breaks (DSBs) are the most dangerous lesions which can lead to carcinogenesis. Nonhomologous end joining (NHEJ) is an important pathway, that allows for recovering DNA by direct end joining. The XRCC6 and LIG4 genes encode respectively Ku70 protein and human ATP-dependent DNA ligase, which are the components of the NHEJ repair pathway. The aim of our study was to evaluate the influence of XRCC6 C1310G and LIG4 T9I genes polymorphisms on colorectal cancer risk among Polish population., Materials and Method: Genotyping was performed using TaqMan probes based on analysis of PCR products amplified in Real Time PCR. The research has been carried out on the material obtained from 100 patients with colorectal cancer and 100 cancer-free individuals who were age and sex-matched as a control group. The results were developed using the chi - squer test and odds ratio (OR)., Results: Odd ratio analysis indicates reduced risk of colorectal cancer for LIG4 T9I polymorphism in heterozygotus model C/T (OR= 0.2717 95% CI= 0.1247-0,5918) and homozygous model T/T (OR= 0.3593 95% CI= 0.1394-0.9266). Similar situation we observed for XRCC6 C1310G gene polymorphism, which indicated on heterozygotus variant C/G (OR= 0.1181 95% CI= 0.0145-0.964) and homozygotus variant G/G (OR= 0.0972 95% CI= 0.0097-0.9713) to decrease the risk of colorectal cancer. Conslusions: Our research revealed XRCC6 C1310G and LIG4 T9I polymorphisms are associated with diminished risk of colorectal cancer. However, to confirm obtained results, a further investigations should be carried out.

Unlabelled: Colorectal cancer (CRC) is one of the deadliest cancers which lie in the incidence of morbidity in second place. Intensive research is to determine and confirm the genetic basis of this disease, which is believed may have a direct relationship with the reduced efficiency of DNA repair systems. The aim of this study was to determine the effect of APEX gene polymorphism Ile64Val on increasing the risk of colorectal cancer in the Polish population., Material and Methods: The blood samples collected from 150 patients diagnosed with colon cancer was used. The control group consisted of 150 healthy subjects. Genotyping was performed by TaqMan method., Results: The results indicate that genotype Ile Val is associated with an increased risk of colorectal cancer (OR 2.069; 95% CI 1,205-3,552; p = 0.008)., Conclusions: Based on these results, we conclude that the APEX gene polymorphism Ile64Val may be associated with an increased risk of colorectal cancer.

Unlabelled: Participation of DNA repair systems in the pathogenesis of cancer has been a suspected phenomenon for a long time. Decreased efficiency in DNA repair translates to their ability to fix and consequently leads to mutations and the process of carcinogenesis. Linking individual polymorphisms of DNA repair systems with an increased risk of colorectal cancer will allow the classification of patients to high-risk groups and their placement under preventive program. The aim of the study was to determine the effect of XPF gene polymorphism Ser835Ser on increasing the risk of colorectal cancer in the Polish population., Material and Methods: as the material blood collected from 146 patients diagnosed with colon cancer was used. The control group consisted of 149 healthy subjects. Genotyping was performed by Taq- Man method., Results: The results indicate that genotype TCC/TCT is associated with an decreased risk of colorectal cancer (OR 0.574; CI 95% 0.335-0.984; p=0.043)., Conclusions: Based on these results, we conclude that the XPF gene polymorphism Ser835Ser may be associated with a decreased risk of colorectal cancer.

Unlabelled: The incidence of colorectal cancer (CRC) is increasing from year to year. Despite intensive research CRC etiology remains unknown. Studies suggest that at the basis of the process of carcinogenesis can lie reduced efficiency of DNA repair mechanisms, often caused by polymorphisms in DNA repair genes. The aim of the study was to determine the relationship between gene polymorphism Lys589Glu of EXO1 gene and modulation of the risk of colorectal cancer in the Polish population. Determination of the molecular basis of carcinogenesis process and predicting increased risk will allow qualifying patients to increased risk group and including them in preventive program., Material and Methods: The material used in study was blood collected from 130 patients diagnosed with colorectal cancer. The control group consisted of 135 healthy people. Genotyping was performed by TaqMan method., Results: The results obtained indicate that the genotype Lys/Glu is associated with an increased risk of colorectal cancer (OR 1.811, 95% Cl 1.031-3.181, p = 0.038)., Conclusion: On the basis of these results, we conclude that Exo1 gene polymorphism Lys589Glu may be associated with an increased risk of colorectal cancer.