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Significance of mitochondrial DNA in colorectal cancer
Danešová, Natálie ; Vodenková, Soňa (advisor) ; Polívková, Zdeňka (referee)
Colorectal cancer is the third most commonly diagnosed cancer worldwide and the second leading cause of cancer death. It is a heterogeneous and multifactorial disease, the development of which takes up to 15 years. In addition to genetic risk factors, external, influenceable factors also contribute to the development of the disease. Patients are often diagnosed in the late stages of the disease, which significantly reduces the chances of their successful treatment. It is therefore necessary to identify appropriate screening, diagnostic, prognostic and predictive biomarkers of the disease. Mitochondria are organelles found in almost all eukaryotic cells and their dysfunction is often involved in the development of cancer. Because mitochondria have their own DNA its changes could serve as a potential biomarker for a closer understanding of the pathogenesis and progression of colorectal cancer. The main goal of this bachelor thesis was to summarize previous studies focused on mitochondrial DNA changes in patients with colorectal cancer and their possible use in clinical practise. Keywords: Colorectal cancer; biomarkers; mitochondria; mtDNA
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The repair of the oxidative DNA damage in Chinese hamster cells deficient in nucleotide excision DNA repair.
Strejčková, Lada ; Hochmann, Jiří (advisor) ; Polívková, Zdeňka (referee)
Nucleotide excision repair (NER) is one of the mechanisms of how to repair DNA damaged by the external influences. First of all, it plays the role when removing the results caused by UV radiation. The damaged bases in the form of pyrimidine dimers are enzymatically splitted out from DNA as part of oligonucleotides. The effect of the UV light on DNA is however manifested also indirectly, by oxidation of the bases. In our experiment we tried to find out whether the cells deficient in nucleotide excision repair are able to repair the damages induced only by oxidative agent. We stated the extent of DNA damages in the cells in vitro and the ability of their re- paration after treatment with the dilution of hydrogen peroxide in different concentrations. During the experiments we used the cell lines of a Chinese hamster, namely the parental cell line AA8 and their derivative UV-20, which is defective in gene ERCC1. This gene takes part in creation of nucleases participating in NER. For measuring of DNA lesions we used the method of alkaline comet assay, the ba- sis of which is alkaline single-cell gel electrophoresis. The principle of this method consists in the detection of DNA strand breaks originating in the damaged alkali-labile sites. We evaluated the number of DNA single-strand breaks. We detected...
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Acquired chromosomal aberrationns in peripheral blood lymphocytes of patients with newly diagnosed cancer and healthy control individuals.
Vodenková, Soňa ; Polívková, Zdeňka (advisor) ; Langová, Martina (referee)
The majority of human cancers arise due to cells inabitily to maintain genomic stability. Cytogenetic changes (especially chromosomal aberrations) in peripheral blood lymphocytes which reflect not only the individual exposure to genotoxic factors, but also individual sensitivity to genotoxic effect and the tumor is late consequence to genotoxic effect. Summary epidemiological prospective studies over the last ten years have shown that increased level of chromosomal aberrations in peripheral blood lymphocytes is predictive of cancer risk. This thesis is focused on the detection of particular types of chromosomal damage in patients with choosed types of newly diagnosed cancers compared to healthy control persons. We cytogenetically analyzed 100 patients with colorectal cancer and 298 controls and 123 patients with breast cancer and 123 controls - healthy women. We compared the percentage of aberrant cells, the percentage of total aberrations, the percentages of chromatid and chromosome aberrations found in patients with both types of tumors and in controls and we verified the predictive value of chromosomal aberrations as a biomarker of cancer risk. In patients with colorectal cancer was statistically significantly increased only the level of chromatid aberrations (CHTA) (1,45±1,28) compared to...
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The influence of the epigallokatechin gallate, elagic acid and curcumin on the cytotoxic effect of mutagens.
Tlučhořová, Drahomíra ; Hochmann, Jiří (advisor) ; Polívková, Zdeňka (referee)
Naturally occurring phenols epigallocatechin gallate (EGCG), ellagic acid and curcumin exhibit antioxidant, antimutagenic and anticarcinogenic activity in a lot of in vivo and in vitro studies. In our study we used comet assay test to determine if these compounds are capable to affect DNA damage of AA8 and HepG2 cells caused by 2-amino-3-methylimidazo [4,5-f] quinoline (IQ), N-nitroso-N-methylurea (MNU) and UVC radiation. Results should say if comet assay test is an appropriate method for antimutagenity tests. We were interested if compounds, which are able to moderate effects of mutagens, would also affect their cytotoxicity. Except MNU and UVC radiation we used also hydrogen peroxide as a reference mutagen. In comet assay curcumin was not able to protect against MNU induced DNA damage sufficiently. However, ellagic acid effectively reduced mutagenic effect of MNU. EGCG decreased the level of DNA breaks induced by IQ and UVC radiation and affected both DNA damage induction and repair of cells incubated with MNU. We chose only EGCG for cytotoxicity tests because it showed the greatest antimutagenity. EGCG increased the number of formed colonies of cells treated with hydrogen peroxide, likely to its antioxidant properties. However EGCG did not decrease cytotoxicity of MNU and UVC radiation and the...
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Acquired chromosomal aberrationns in peripheral blood lymphocytes of patients with newly diagnosed cancer and healthy control individuals.
Vodenková, Soňa ; Polívková, Zdeňka (advisor) ; Langová, Martina (referee)
The majority of human cancers arise due to cells inabitily to maintain genomic stability. Cytogenetic changes (especially chromosomal aberrations) in peripheral blood lymphocytes which reflect not only the individual exposure to genotoxic factors, but also individual sensitivity to genotoxic effect and the tumor is late consequence to genotoxic effect. Summary epidemiological prospective studies over the last ten years have shown that increased level of chromosomal aberrations in peripheral blood lymphocytes is predictive of cancer risk. This thesis is focused on the detection of particular types of chromosomal damage in patients with choosed types of newly diagnosed cancers compared to healthy control persons. We cytogenetically analyzed 100 patients with colorectal cancer and 298 controls and 123 patients with breast cancer and 123 controls - healthy women. We compared the percentage of aberrant cells, the percentage of total aberrations, the percentages of chromatid and chromosome aberrations found in patients with both types of tumors and in controls and we verified the predictive value of chromosomal aberrations as a biomarker of cancer risk. In patients with colorectal cancer was statistically significantly increased only the level of chromatid aberrations (CHTA) (1,45±1,28) compared to...
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The influence of the epigallokatechin gallate, elagic acid and curcumin on the cytotoxic effect of mutagens.
Tlučhořová, Drahomíra ; Hochmann, Jiří (advisor) ; Polívková, Zdeňka (referee)
Naturally occurring phenols epigallocatechin gallate (EGCG), ellagic acid and curcumin exhibit antioxidant, antimutagenic and anticarcinogenic activity in a lot of in vivo and in vitro studies. In our study we used comet assay test to determine if these compounds are capable to affect DNA damage of AA8 and HepG2 cells caused by 2-amino-3-methylimidazo [4,5-f] quinoline (IQ), N-nitroso-N-methylurea (MNU) and UVC radiation. Results should say if comet assay test is an appropriate method for antimutagenity tests. We were interested if compounds, which are able to moderate effects of mutagens, would also affect their cytotoxicity. Except MNU and UVC radiation we used also hydrogen peroxide as a reference mutagen. In comet assay curcumin was not able to protect against MNU induced DNA damage sufficiently. However, ellagic acid effectively reduced mutagenic effect of MNU. EGCG decreased the level of DNA breaks induced by IQ and UVC radiation and affected both DNA damage induction and repair of cells incubated with MNU. We chose only EGCG for cytotoxicity tests because it showed the greatest antimutagenity. EGCG increased the number of formed colonies of cells treated with hydrogen peroxide, likely to its antioxidant properties. However EGCG did not decrease cytotoxicity of MNU and UVC radiation and the...
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The oxidative DNA damage and its relationship to the cytotoxic effect.
Blahová, Hana ; Hochmann, Jiří (advisor) ; Polívková, Zdeňka (referee)
This work has been focused on the study of oxidative DNA damage induced with hydrogen peroxide and on the relationship of this damage to cytotoxic effect . The repair of the oxidative DNA damage and the cell survival was followed both in normal Chinese hamster cells and their mutant derivative UV-20. The modified single cell gel electrophoresis (the comet assay,) was used to estimate the DNA damage. The cytotoxiciy was measured using the inhibition of colony forming capacity of cells. Both normal AA8 and mutant UV-20 cells repair the oxidative DNA damage with approximately the same velocity, and they show also the same sensitivity towards the hydrogen peroxide. These results indicate, that the defect in the nucleotide excision DNA repair in UV-20 cells does not play any important role in the response of these cells to the oxidative DNA damage, and therefore this mechanism is not involved in the removal of this damage. This may indicate, that the main mechanism of the repair of oxidative DNA damage is the base excision repair. Keywords: Oxidative DNA damage, hydrogen peroxide, comet assay, excision repair.
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The repair of the oxidative DNA damage in Chinese hamster cells deficient in nucleotide excision DNA repair.
Strejčková, Lada ; Hochmann, Jiří (advisor) ; Polívková, Zdeňka (referee)
Nucleotide excision repair (NER) is one of the mechanisms of how to repair DNA damaged by the external influences. First of all, it plays the role when removing the results caused by UV radiation. The damaged bases in the form of pyrimidine dimers are enzymatically splitted out from DNA as part of oligonucleotides. The effect of the UV light on DNA is however manifested also indirectly, by oxidation of the bases. In our experiment we tried to find out whether the cells deficient in nucleotide excision repair are able to repair the damages induced only by oxidative agent. We stated the extent of DNA damages in the cells in vitro and the ability of their re- paration after treatment with the dilution of hydrogen peroxide in different concentrations. During the experiments we used the cell lines of a Chinese hamster, namely the parental cell line AA8 and their derivative UV-20, which is defective in gene ERCC1. This gene takes part in creation of nucleases participating in NER. For measuring of DNA lesions we used the method of alkaline comet assay, the ba- sis of which is alkaline single-cell gel electrophoresis. The principle of this method consists in the detection of DNA strand breaks originating in the damaged alkali-labile sites. We evaluated the number of DNA single-strand breaks. We detected...
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