@article{AdamAhrweilerSahaMoelleretal.1993, author = {Adam, W. and Ahrweiler, M. and Saha-M{\"o}ller, C. R. and Sauter, M. and Sch{\"o}nberger, A. and Epe, B. and M{\"u}ller, E. and Schiffmann, D. and Stopper, Helga and Wild, D.}, title = {Genotoxicity studies of benzofuran dioxetanes and epoxides with isolated DNA, bacteria and mammalian cells}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-63420}, year = {1993}, abstract = {1.2-Dioxetanes, very reactive and high energy molecules. are involved as labile intermediates in dioxygenase- activated aerobic metabolism and in physiological processes. Various toxico1ogica1 tests reveal that dioxetanes are indeed genotoxic. In supercoiled DNA of bacteriophage PM2 they induce endonucleasesensitive sites, most of them are FPG protein-sensitive base modifications (8-hydroxyguanine, fonnamidopyrimidines). Pyrimidinedimersand sites ofbase loss (AP sites) which were probed by UV endonuclease and exonuclease 111 are minor lesions in this system. While the alky1-substituted dioxetanes do not show any significant mutagenic activity in different Salmonella typhimurium strains, heteroarene dioxetanes such as benzofuran and furocoumarin dioxetanes are strongly mutagenic in S. typhimurium strain TA I 00. DNA adducts formed with an intermediary alkyJating agent appear to be responsible for the mutagenic activity of benzofuran dioxetane. We assume that the benzofuran epoxides, generated in situ from benzofuran dioxetanes by deoxygenation are the ultimate mutagens of the latter. since benzofuran epoxides are highly mutagenic in the S. typhimurium strain TAIOO and they form DNA adducts. as detected by the 212Ppostlabelling technique. Our results imply that the type of D NA darnage promoted by dioxetanes is dependent on the structural feature of dioxetanes. Furthermore, the direct photochemical DNA darnage by energy transfer. i.e., pyrimidine dimers, plays a minor role in the genotoxicity of dioxetanes. Instead, photooxidation dominates in isolated DNA. while radical darnage and alkylation prevail in the cellular system.}, subject = {Toxikologie}, language = {en} } @article{BankogluSchueleStopper2021, author = {Bankoglu, Ezgi Eyluel and Schuele, Carolin and Stopper, Helga}, title = {Cell survival after DNA damage in the comet assay}, series = {Archives of Toxicology}, volume = {95}, journal = {Archives of Toxicology}, number = {12}, doi = {10.1007/s00204-021-03164-3}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-265339}, pages = {3803-3813}, year = {2021}, abstract = {The comet assay is widely used in basic research, genotoxicity testing, and human biomonitoring. However, interpretation of the comet assay data might benefit from a better understanding of the future fate of a cell with DNA damage. DNA damage is in principle repairable, or if extensive, can lead to cell death. Here, we have correlated the maximally induced DNA damage with three test substances in TK6 cells with the survival of the cells. For this, we selected hydrogen peroxide (H\(_{2}\)O\(_{2}\)) as an oxidizing agent, methyl methanesulfonate (MMS) as an alkylating agent and etoposide as a topoisomerase II inhibitor. We measured cell viability, cell proliferation, apoptosis, and micronucleus frequency on the following day, in the same cell culture, which had been analyzed in the comet assay. After treatment, a concentration dependent increase in DNA damage and in the percentage of non-vital and apoptotic cells was found for each substance. Values greater than 20-30\% DNA in tail caused the death of more than 50\% of the cells, with etoposide causing slightly more cell death than H\(_{2}\)O\(_{2}\) or MMS. Despite that, cells seemed to repair of at least some DNA damage within few hours after substance removal. Overall, the reduction of DNA damage over time is due to both DNA repair and death of heavily damaged cells. We recommend that in experiments with induction of DNA damage of more than 20\% DNA in tail, survival data for the cells are provided.}, language = {en} } @article{BankogluStippGerberetal.2021, author = {Bankoglu, Ezgi Eyluel and Stipp, Franzisca and Gerber, Johanna and Seyfried, Florian and Heidland, August and Bahner, Udo and Stopper, Helga}, title = {Effect of cryopreservation on DNA damage and DNA repair activity in human blood samples in the comet assay}, series = {Archives of Toxicology}, volume = {95}, journal = {Archives of Toxicology}, number = {5}, doi = {10.1007/s00204-021-03012-4}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-265326}, pages = {1831-1841}, year = {2021}, abstract = {The comet assay is a commonly used method to determine DNA damage and repair activity in many types of samples. In recent years, the use of the comet assay in human biomonitoring became highly attractive due to its various modified versions, which may be useful to determine individual susceptibility in blood samples. However, in human biomonitoring studies, working with large sample numbers that are acquired over an extended time period requires some additional considerations. One of the most important issues is the storage of samples and its effect on the outcome of the comet assay. Another important question is the suitability of different blood preparations. In this study, we analysed the effect of cryopreservation on DNA damage and repair activity in human blood samples. In addition, we investigated the suitability of different blood preparations. The alkaline and FPG as well as two different types of repair comet assay and an in vitro hydrogen peroxide challenge were applied. Our results confirmed that cryopreserved blood preparations are suitable for investigating DNA damage in the alkaline and FPG comet assay in whole blood, buffy coat and PBMCs. Ex vivo hydrogen peroxide challenge yielded its optimal effect in isolated PBMCs. The utilised repair comet assay with either UVC or hydrogen peroxide-induced lesions and an aphidicolin block worked well in fresh PBMCs. Cryopreserved PBMCs could not be used immediately after thawing. However, a 16-h recovery with or without mitotic stimulation enabled the application of the repair comet assay, albeit only in a surviving cell fraction.}, language = {en} } @article{BenKhaledHammerYeetal.2022, author = {Ben Khaled, Najib and Hammer, Katharina and Ye, Liangtao and Alnatsha, Ahmed and Widholz, Sebastian A. and Piseddu, Ignazio and Sirtl, Simon and Schneider, Julia and Munker, Stefan and Mahajan, Ujjwal Mukund and Montero, Juan Jos{\´e} and Griger, Joscha and Mayerle, Julia and Reiter, Florian P. and De Toni, Enrico N.}, title = {TRAIL receptor targeting agents potentiate PARP inhibitor efficacy in pancreatic cancer independently of BRCA2 mutation status}, series = {Cancers}, volume = {14}, journal = {Cancers}, number = {21}, issn = {2072-6694}, doi = {10.3390/cancers14215240}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-290884}, year = {2022}, abstract = {Chemotherapy, the standard treatment for pancreatic ductal adenocarcinoma (PDAC), has only a modest effect on the outcome of patients with late-stage disease. Investigations of the genetic features of PDAC have demonstrated a frequent occurrence of mutations in genes involved in homologous recombination (HR), especially in the breast cancer susceptibility gene 2 (BRCA2). Olaparib, a poly(ADP-ribose) polymerase (PARP) inhibitor, is approved as a maintenance treatment for patients with advanced PDAC with germline BRCA1/2 mutations following a platinum-containing first-line regimen. Limitations to the use of PARP inhibitors are represented by the relatively small proportion of patients with mutations in BRCA1/2 genes and the modest capability of these substances of inducing objective response. We have previously shown that pancreatic cancer with BRCA2 mutations exhibits a remarkably enhanced sensitivity towards tumor-necrosis-factor-related apoptosis-inducing ligand (TRAIL) receptor-stimulating agents. We thus aimed to investigate the effect of combined treatment with PARP inhibitors and TRAIL receptor-stimulating agents in pancreatic cancer and its dependency on the BRCA2 gene status. The respective effects of TRAIL-targeting agents and the PARP inhibitor olaparib or of their combination were assessed in pancreatic cancer cell lines and patient-derived organoids. In addition, BRCA2-knockout and -complementation models were investigated. The effects of these agents on apoptosis, DNA damage, cell cycle, and receptor surface expression were assessed by immunofluorescence, Western blot, and flow cytometry. PARP inhibition and TRAIL synergized to cause cell death in pancreatic cancer cell lines and PDAC organoids. This effect proved independent of BRCA2 gene status in three independent models. Olaparib and TRAIL in combination caused a detectable increase in DNA damage and a concentration-dependent cell cycle arrest in the G2/M and S cell cycle phases. Olaparib also significantly increased the proportion of membrane-bound death receptor 5. Our results provide a preclinical rationale for the combination of PARP inhibitors and TRAIL receptor agonists for the treatment of pancreatic cancer and suggest that the use of PARP inhibitors could be extended to patients without BRCA2 mutations if used in combination with TRAIL agonists.}, language = {en} } @article{BrandAmannMandeletal.2014, author = {Brand, Susanne and Amann, Kerstin and Mandel, Philipp and Zimnol, Anna and Schupp, Nicole}, title = {Oxidative DNA Damage in Kidneys and Heart of Hypertensive Mice Is Prevented by Blocking Angiotensin II and Aldosterone Receptors}, series = {PLOS ONE}, volume = {9}, journal = {PLOS ONE}, number = {12}, issn = {1932-6203}, doi = {10.1371/journal.pone.0115715}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-118011}, pages = {e115715}, year = {2014}, abstract = {INTRODUCTION: Recently, we could show that angiotensin II, the reactive peptide of the blood pressure-regulating renin-angiotensin-aldosterone-system, causes the formation of reactive oxygen species and DNA damage in kidneys and hearts of hypertensive mice. To further investigate on the one hand the mechanism of DNA damage caused by angiotensin II, and on the other hand possible intervention strategies against end-organ damage, the effects of substances interfering with the renin-angiotensin-aldosterone-system on angiotensin II-induced genomic damage were studied. METHODS: In C57BL/6-mice, hypertension was induced by infusion of 600 ng/kg • min angiotensin II. The animals were additionally treated with the angiotensin II type 1 receptor blocker candesartan, the mineralocorticoid receptor blocker eplerenone and the antioxidant tempol. DNA damage and the activation of transcription factors were studied by immunohistochemistry and protein expression analysis. RESULTS: Administration of angiotensin II led to a significant increase of blood pressure, decreased only by candesartan. In kidneys and hearts of angiotensin II-treated animals, significant oxidative stress could be detected (1.5-fold over control). The redox-sensitive transcription factors Nrf2 and NF-κB were activated in the kidney by angiotensin II-treatment (4- and 3-fold over control, respectively) and reduced by all interventions. In kidneys and hearts an increase of DNA damage (3- and 2-fold over control, respectively) and of DNA repair (3-fold over control) was found. These effects were ameliorated by all interventions in both organs. Consistently, candesartan and tempol were more effective than eplerenone. CONCLUSION: Angiotensin II-induced DNA damage is caused by angiotensin II type 1 receptor-mediated formation of oxidative stress in vivo. The angiotensin II-mediated physiological increase of aldosterone adds to the DNA-damaging effects. Blocking angiotensin II and mineralocorticoid receptors therefore has beneficial effects on end-organ damage independent of blood pressure normalization.}, language = {en} } @article{DjelićBorozanDimitrijevićSrećkovićetal.2022, author = {Djelić, Ninoslav and Borozan, Sunčica and Dimitrijević-Srećković, Vesna and Pajović, Nevena and Mirilović, Milorad and Stopper, Helga and Stanimirović, Zoran}, title = {Oxidative stress and DNA damage in peripheral blood mononuclear cells from normal, obese, prediabetic and diabetic persons exposed to thyroid hormone in vitro}, series = {International Journal of Molecular Sciences}, volume = {23}, journal = {International Journal of Molecular Sciences}, number = {16}, issn = {1422-0067}, doi = {10.3390/ijms23169072}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-285988}, year = {2022}, abstract = {Diabetes, a chronic group of medical disorders characterized byhyperglycemia, has become a global pandemic. Some hormones may influence the course and outcome of diabetes, especially if they potentiate the formation of reactive oxygen species (ROS). There is a close relationship between thyroid disorders and diabetes. The main objective of this investigation was to find out whether peripheral blood mononuclear cells (PBMCs) are more prone to DNA damage by triiodothyronine (T\(_3\)) (0.1, 1 and 10 μM) at various stages of progression through diabetes (obese, prediabetics, and type 2 diabetes mellitus—T2DM persons). In addition, some biochemical parameters of oxidative stress (catalase-CAT, thiobarbituric acid reactive substances—TBARS) and lactate dehydrogenase (LDH) were evaluated. PBMCs from prediabetic and diabetic patients exhibited increased sensitivity for T\(_3\) regarding elevated level of DNA damage, inhibition of catalase, and increase of TBARS and LDH. PBMCs from obese patients reacted in the same manner, except for DNA damage. The results of this study should contribute to a better understanding of the role of thyroid hormones in the progression of T2DM.}, language = {en} } @article{DjuzenovaElsnerKatzeretal.2013, author = {Djuzenova, Cholpon S. and Elsner, Ines and Katzer, Astrid and Worschech, Eike and Distel, Luitpold V. and Flentje, Michael and Polat, B{\"u}lent}, title = {Radiosensitivity in breast cancer assessed by the histone γ-H2AX and 53BP1 foci}, series = {Radiation Oncology}, journal = {Radiation Oncology}, doi = {10.1186/1748-717X-8-98}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-96110}, year = {2013}, abstract = {Background High expression of constitutive histone γ-H2AX, a sensitive marker of DNA damage, might be indicative of defective DNA repair pathway or genomic instability. 53BP1 (p53-binding protein 1) is a conserved checkpoint protein with properties of a DNA double-strand breaks sensor. This study explores the relationship between the clinical radiosensitivity of tumor patients and the expression/induction of γ-H2AX and 53BP1 in vitro. Methods Using immunostaining, we assessed spontaneous and radiation-induced foci of γ-H2AX and 53 BP1 in peripheral blood mononuclear cells derived from unselected breast cancer (BC) patients (n=57) undergoing radiotherapy (RT). Cells from apparently healthy donors (n=12) served as references. Results Non-irradiated cells from controls and unselected BC patients exhibited similar baseline levels of DNA damage assessed by γ-H2AX and 53BP1 foci. At the same time, the γ-H2AX assay of in vitro irradiated cells revealed significant differences between the control group and the group of unselected BC patients with respect to the initial (0.5 Gy, 30 min) and residual (2 Gy, 24 h post-radiation) DNA damage. The numbers of 53BP1 foci analyzed in 35 BC patients were significantly higher than in controls only in case of residual DNA damage. A weak correlation was found between residual foci of both proteins tested. In addition, cells from cancer patients with an adverse acute skin reaction (grade 3) to RT showed significantly increased radiation-induced γ-H2AX foci and their protracted disappearance compared to the group of BC patients with normal skin reaction (grade 0-1). The mean number of γ-H2AX foci after 5 clinical fractions was significantly higher than that before RT, especially in clinically radiosensitive patients. Conclusions The γ-H2AX assay may have potential for screening individual radiosensitivity of breast cancer patients.}, subject = {DNS-Sch{\"a}digung}, language = {en} } @article{DjuzenovaFiedlerKatzeretal.2016, author = {Djuzenova, Cholpon S. and Fiedler, Vanessa and Katzer, Astrid and Michel, Konstanze and Deckert, Stefanie and Zimmermann, Heiko and Sukhorukov, Vladimir L. and Flentje, Michael}, title = {Dual PI3K-and mTOR-inhibitor PI-103 can either enhance or reduce the radiosensitizing effect of the Hsp90 inhibitor NVP-AUY922 in tumor cells: The role of drug-irradiation schedule}, series = {Oncotarget}, volume = {7}, journal = {Oncotarget}, number = {25}, doi = {10.18632/oncotarget.9501}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-177770}, pages = {38191-38209}, year = {2016}, abstract = {Inhibition of Hsp90 can increase the radiosensitivity of tumor cells. However, inhibition of Hsp90 alone induces the anti-apoptotic Hsp70 and thereby decreases radiosensitivity. Therefore, preventing Hsp70 induction can be a promising strategy for radiosensitization. PI-103, an inhibitor of PI3K and mTOR, has previously been shown to suppress the up-regulation of Hsp70. Here, we explore the impact of combining PI-103 with the Hsp90 inhibitor NVP-AUY922 in irradiated glioblastoma and colon carcinoma cells. We analyzed the cellular response to drug-irradiation treatments by colony-forming assay, expression of several marker proteins, cell cycle progression and induction/repair of DNA damage. Although PI-103, given 24 h prior to irradiation, slightly suppressed the NVP-AUY922-mediated up-regulation of Hsp70, it did not cause radiosensitization and even diminished the radiosensitizing effect of NVP-AUY922. This result can be explained by the activation of PI3K and ERK pathways along with G1-arrest at the time of irradiation. In sharp contrast, PI-103 not only exerted a radiosensitizing effect but also strongly enhanced the radiosensitization by NVP-AUY922 when both inhibitors were added 3 h before irradiation and kept in culture for 24 h. Possible reasons for the observed radiosensitization under this drug-irradiation schedule may be a down-regulation of PI3K and ERK pathways during or directly after irradiation, increased residual DNA damage and strong G2/M arrest 24 h thereafter. We conclude that duration of drug treatment before irradiation plays a key role in the concomitant targeting of PI3K/mTOR and Hsp90 in tumor cells.}, language = {en} } @article{DjuzenovaFiedlerMemmeletal.2019, author = {Djuzenova, Cholpon S. and Fiedler, Vanessa and Memmel, Simon and Katzer, Astrid and Sisario, Dmitri and Brosch, Philippa K. and G{\"o}hrung, Alexander and Frister, Svenja and Zimmermann, Heiko and Flentje, Michael and Sukhorukov, Vladimir L.}, title = {Differential effects of the Akt inhibitor MK-2206 on migration and radiation sensitivity of glioblastoma cells}, series = {BMC Cancer}, volume = {19}, journal = {BMC Cancer}, doi = {10.1186/s12885-019-5517-4}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-200290}, pages = {299}, year = {2019}, abstract = {Background Most tumor cells show aberrantly activated Akt which leads to increased cell survival and resistance to cancer radiotherapy. Therefore, targeting Akt can be a promising strategy for radiosensitization. Here, we explore the impact of the Akt inhibitor MK-2206 alone and in combination with the dual PI3K and mTOR inhibitor PI-103 on the radiation sensitivity of glioblastoma cells. In addition, we examine migration of drug-treated cells. Methods Using single-cell tracking and wound healing migration tests, colony-forming assay, Western blotting, flow cytometry and electrorotation we examined the effects of MK-2206 and PI-103 and/or irradiation on the migration, radiation sensitivity, expression of several marker proteins, DNA damage, cell cycle progression and the plasma membrane properties in two glioblastoma (DK-MG and SNB19) cell lines, previously shown to differ markedly in their migratory behavior and response to PI3K/mTOR inhibition. Results We found that MK-2206 strongly reduces the migration of DK-MG but only moderately reduces the migration of SNB19 cells. Surprisingly, MK-2206 did not cause radiosensitization, but even increased colony-forming ability after irradiation. Moreover, MK-2206 did not enhance the radiosensitizing effect of PI-103. The results appear to contradict the strong depletion of p-Akt in MK-2206-treated cells. Possible reasons for the radioresistance of MK-2206-treated cells could be unaltered or in case of SNB19 cells even increased levels of p-mTOR and p-S6, as compared to the reduced expression of these proteins in PI-103-treated samples. We also found that MK-2206 did not enhance IR-induced DNA damage, neither did it cause cell cycle distortion, nor apoptosis nor excessive autophagy. Conclusions Our study provides proof that MK-2206 can effectively inhibit the expression of Akt in two glioblastoma cell lines. However, due to an aberrant activation of mTOR in response to Akt inhibition in PTEN mutated cells, the therapeutic window needs to be carefully defined, or a combination of Akt and mTOR inhibitors should be considered.}, language = {en} } @article{DjuzenovaFischerKatzeretal.2021, author = {Djuzenova, Cholpon S. and Fischer, Thomas and Katzer, Astrid and Sisario, Dmitri and Korsa, Tessa and Streussloff, Gudrun and Sukhorukov, Vladimir L. and Flentje, Michael}, title = {Opposite effects of the triple target (DNA-PK/PI3K/mTOR) inhibitor PI-103 on the radiation sensitivity of glioblastoma cell lines proficient and deficient in DNA-PKcs}, series = {BMC Cancer}, volume = {21}, journal = {BMC Cancer}, doi = {10.1186/s12885-021-08930-1}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-265826}, year = {2021}, abstract = {Background: Radiotherapy is routinely used to combat glioblastoma (GBM). However, the treatment efficacy is often limited by the radioresistance of GBM cells. Methods: Two GBM lines MO59K and MO59J, differing in intrinsic radiosensitivity and mutational status of DNA-PK and ATM, were analyzed regarding their response to DNA-PK/PI3K/mTOR inhibition by PI-103 in combination with radiation. To this end we assessed colony-forming ability, induction and repair of DNA damage by gamma H2AX and 53BP1, expression of marker proteins, including those belonging to NHEJ and HR repair pathways, degree of apoptosis, autophagy, and cell cycle alterations. Results: We found that PI-103 radiosensitized MO59K cells but, surprisingly, it induced radiation resistance in MO59J cells. Treatment of MO59K cells with PI-103 lead to protraction of the DNA damage repair as compared to drug-free irradiated cells. In PI-103-treated and irradiated MO59J cells the foci numbers of both proteins was higher than in the drug-free samples, but a large portion of DNA damage was quickly repaired. Another cell line-specific difference includes diminished expression of p53 in MO59J cells, which was further reduced by PI-103. Additionally, PI-103-treated MO59K cells exhibited an increased expression of the apoptosis marker cleaved PARP and increased subG1 fraction. Moreover, irradiation induced a strong G2 arrest in MO59J cells (similar to 80\% vs. similar to 50\% in MO59K), which was, however, partially reduced in the presence of PI-103. In contrast, treatment with PI-103 increased the G2 fraction in irradiated MO59K cells. Conclusions: The triple-target inhibitor PI-103 exerted radiosensitization on MO59K cells, but, unexpectedly, caused radioresistance in the MO59J line, lacking DNA-PK. The difference is most likely due to low expression of the DNA-PK substrate p53 in MO59J cells, which was further reduced by PI-103. This led to less apoptosis as compared to drug-free MO59J cells and enhanced survival via partially abolished cell-cycle arrest. The findings suggest that the lack of DNA-PK-dependent NHEJ in MO59J line might be compensated by DNA-PK independent DSB repair via a yet unknown mechanism.}, language = {en} } @article{DjuzenovaZimmermannKatzeretal.2015, author = {Djuzenova, Cholpon S. and Zimmermann, Marcus and Katzer, Astrid and Fiedler, Vanessa and Distel, Luitpold V. and Gasser, Martin and Waaga-Gasser, Anna-Maria and Flentje, Michael and Polat, B{\"u}lent}, title = {A prospective study on histone γ-H2AX and 53BP1 foci expression in rectal carcinoma patients: correlation with radiation therapy-induced outcome}, series = {BMC Cancer}, volume = {15}, journal = {BMC Cancer}, number = {856}, doi = {10.1186/s12885-015-1890-9}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-125303}, year = {2015}, abstract = {Background The prognostic value of histone γ-H2AX and 53BP1 proteins to predict the radiotherapy (RT) outcome of patients with rectal carcinoma (RC) was evaluated in a prospective study. High expression of the constitutive histone γ-H2AX is indicative of defective DNA repair pathway and/or genomic instability, whereas 53BP1 (p53-binding protein 1) is a conserved checkpoint protein with properties of a DNA double-strand breaks sensor. Methods Using fluorescence microscopy, we assessed spontaneous and radiation-induced foci of γ-H2AX and 53BP1 in peripheral blood mononuclear cells derived from unselected RC patients (n = 53) undergoing neoadjuvant chemo- and RT. Cells from apparently healthy donors (n = 12) served as references. Results The γ-H2AX assay of in vitro irradiated lymphocytes revealed significantly higher degree of DNA damage in the group of unselected RC patients with respect to the background, initial (0.5 Gy, 30 min) and residual (0.5 Gy and 2 Gy, 24 h post-radiation) damage compared to the control group. Likewise, the numbers of 53BP1 foci analyzed in the samples from 46 RC patients were significantly higher than in controls except for the background DNA damage. However, both markers were not able to predict tumor stage, gastrointestinal toxicity or tumor regression after curative RT. Interestingly, the mean baseline and induced DNA damage was found to be lower in the group of RC patients with tumor stage IV (n = 7) as compared with the stage III (n = 35). The difference, however, did not reach statistical significance, apparently, because of the limited number of patients. Conclusions The study shows higher expression of γ-H2AX and 53BP1 foci in rectal cancer patients compared with healthy individuals. Yet the data in vitro were not predictive in regard to the radiotherapy outcome.}, language = {en} } @article{HenrikssonCalderonMontanoSolvieetal.2022, author = {Henriksson, Sofia and Calder{\´o}n-Monta{\~n}o, Jos{\´e} Manuel and Solvie, Daniel and Warpman Berglund, Ulrika and Helleday, Thomas}, title = {Overexpressed c-Myc sensitizes cells to TH1579, a mitotic arrest and oxidative DNA damage inducer}, series = {Biomolecules}, volume = {12}, journal = {Biomolecules}, number = {12}, issn = {2218-273X}, doi = {10.3390/biom12121777}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-297547}, year = {2022}, abstract = {Previously, we reported that MTH1 inhibitors TH588 and TH1579 selectively induce oxidative damage and kill Ras-expressing or -transforming cancer cells, as compared to non-transforming immortalized or primary cells. While this explains the impressive anti-cancer properties of the compounds, the molecular mechanism remains elusive. Several oncogenes induce replication stress, resulting in under replicated DNA and replication continuing into mitosis, where TH588 and TH1579 treatment causes toxicity and incorporation of oxidative damage. Hence, we hypothesized that oncogene-induced replication stress explains the cancer selectivity. To test this, we overexpressed c-Myc in human epithelial kidney cells (HA1EB), resulting in increased proliferation, polyploidy and replication stress. TH588 and TH1579 selectively kill c-Myc overexpressing clones, enforcing the cancer cell selective killing of these compounds. Moreover, the toxicity of TH588 and TH1579 in c-Myc overexpressing cells is rescued by transcription, proteasome or CDK1 inhibitors, but not by nucleoside supplementation. We conclude that the molecular toxicological mechanisms of how TH588 and TH1579 kill c-Myc overexpressing cells have several components and involve MTH1-independent proteasomal degradation of c-Myc itself, c-Myc-driven transcription and CDK activation.}, language = {en} } @article{HohenauerBerkingSchmidtetal.2013, author = {Hohenauer, Tobias and Berking, Carola and Schmidt, Andreas and Haferkamp, Sebastian and Senft, Daniela and Kammerbauer, Claudia and Fraschka, Sabine and Graf, Saskia Anna and Irmler, Martin and Beckers, Johannes and Flaig, Michael and Aigner, Achim and H{\"o}bel, Sabrina and Hoffmann, Franziska and Hermeking, Heiko and Rothenfusser, Simon and Endres, Stefan and Ruzicka, Thomas and Besch, Robert}, title = {The neural crest transcription factor Brn3a is expressed in melanoma and required for cell cycle progression and survival}, series = {EMBO Molecular Medicine}, volume = {5}, journal = {EMBO Molecular Medicine}, issn = {1757-4676}, doi = {10.1002/emmm.201201862}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-122193}, pages = {919-934}, year = {2013}, abstract = {Pigment cells and neuronal cells both are derived from the neural crest. Here, we describe the Pit-Oct-Unc (POU) domain transcription factor Brn3a, normally involved in neuronal development, to be frequently expressed in melanoma, but not in melanocytes and nevi. RNAi-mediated silencing of Brn3a strongly reduced the viability of melanoma cell lines and decreased tumour growth in vivo. In melanoma cell lines, inhibition of Brn3a caused DNA double-strand breaks as evidenced by Mre11/Rad50-containing nuclear foci. Activated DNA damage signalling caused stabilization of the tumour suppressor p53, which resulted in cell cycle arrest and apoptosis. When Brn3a was ectopically expressed in primary melanocytes and fibroblasts, anchorage-independent growth was increased. In tumourigenic melanocytes and fibroblasts, Brn3a accelerated tumour growth in vivo. Furthermore, Brn3a cooperated with proliferation pathways such as oncogenic BRAF, by reducing oncogene-induced senescence in non-malignant melanocytes. Together, these results identify Brn3a as a new factor in melanoma that is essential for melanoma cell survival and that promotes melanocytic transformation and tumourigenesis.}, language = {en} } @article{KroeberWengerSchwegleretal.2015, author = {Kroeber, Jana and Wenger, Barbara and Schwegler, Manuela and Daniel, Christoph and Schmidt, Manfred and Djuzenova, Cholpon S and Polat, B{\"u}lent and Flentje, Michael and Fietkau, Rainer and Distel, Luitpold V.}, title = {Distinct increased outliers among 136 rectal cancer patients assessed by \(\gamma\)H2AX}, series = {Radiation Oncology}, volume = {10}, journal = {Radiation Oncology}, number = {36}, doi = {10.1186/s13014-015-0344-5}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-144085}, year = {2015}, abstract = {Background: In recent years attention has focused on \(\gamma\)H2AX as a very sensitive double strand break indicator. It has been suggested that \(\gamma\)H2AX might be able to predict individual radiosensitivity. Our aim was to study the induction and repair of DNA double strand breaks labelled by \(\gamma\)H2AX in a large cohort. Methods: In a prospective study lymphocytes of 136 rectal cancer (RC) patients and 59 healthy individuals were ex vivo irradiated (IR) and initial DNA damage was compared to remaining DNA damage after 2 Gy and 24 hours repair time and preexisting DNA damage in unirradiated lymphocytes. Lymphocytes were immunostained with anti-\(\gamma\)H2AX antibodies and microscopic images with an extended depth of field were acquired. \(\gamma\)H2AX foci counting was performed using a semi-automatic image analysis software. Results: Distinct increased values of preexisting and remaining \(\gamma\)H2AX foci in the group of RC patients were found compared to the healthy individuals. Additionally there are clear differences within the groups and there are outliers in about 12\% of the RC patients after ex vivo IR. Conclusions: The \(\gamma\)H2AX assay has the capability to identify a group of outliers which are most probably patients with increased radiosensitivity having the highest risk of suffering radiotherapy-related late sequelae.}, language = {en} } @article{LeikamHufnagelOttoetal.2015, author = {Leikam, C and Hufnagel, AL and Otto, C and Murphy, DJ and M{\"u}hling, B and Kneitz, S and Nanda, I and Schmid, M and Wagner, TU and Haferkamp, S and Br{\"o}cker, E-B and Schartl, M and Meierjohann, S}, title = {In vitro evidence for senescent multinucleated melanocytes as a source for tumor-initiating cells}, series = {Cell Death and Disease}, volume = {6}, journal = {Cell Death and Disease}, number = {e1711}, doi = {10.1038/cddis.2015.71}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-148718}, year = {2015}, abstract = {Oncogenic signaling in melanocytes results in oncogene-induced senescence (OIS), a stable cell-cycle arrest frequently characterized by a bi-or multinuclear phenotype that is considered as a barrier to cancer progression. However, the long-sustained conviction that senescence is a truly irreversible process has recently been challenged. Still, it is not known whether cells driven into OIS can progress to cancer and thereby pose a potential threat. Here, we show that prolonged expression of the melanoma oncogene N-RAS\(^{61K}\) in pigment cells overcomes OIS by triggering the emergence of tumor-initiating mononucleated stem-like cells from senescent cells. This progeny is dedifferentiated, highly proliferative, anoikis-resistant and induces fast growing, metastatic tumors. Our data describe that differentiated cells, which are driven into senescence by an oncogene, use this senescence state as trigger for tumor transformation, giving rise to highly aggressive tumor-initiating cells. These observations provide the first experimental in vitro evidence for the evasion of OIS on the cellular level and ensuing transformation.}, language = {en} } @article{Lutz1990, author = {Lutz, Werner K.}, title = {Endogenous genotoxic agents and processes as a basis of spontaneous carcinogenesis}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-60816}, year = {1990}, abstract = {A list ofendogenaus DNA·damaging agents and processes is given. Endogenaus e/ectrophiles are found with the cosubstrates of physiological transfer reactions (S-adenosylrnethionine for methylation, A TP for phosphorylation, NAD\(^+\) for ADP-ribosylation, acetyl CoA for acetylation). Aldehyde groups (glyceraldehyde- 3-phosphate, formaldehyde, open forms of reducing sugars, degradation products of peroxidation) or alkylating degradation products derived from endogenaus nitrose compounds represent additional possibilities. Radical-forming reactions include leakage of the superoxide anion radical from terminal cytochromes and redox cycles, hydroxyl radical formation by the Fenton reaction from endogenaus hydrogen peroxide, and the formation of lipid peroxides. Genetic instability by spontaneaus deaminations and depurinations as well as replicative instability by tautomer errors andin the presence of mutagenic metal ions represent a third important dass of endogenaus genotoxic processes. The postulated endogenaus genotoxicity could form the mechanistic basis for what is called 'spontaneous' tumor incidence and explain the possibility of an increased tumor incidence after treatment of animals with non-genotoxic compounds exhibiting tumor-promoting activity only. Individual differences are expected to be seen also with endogenaus DNA damage. The presence of endogenaus DNA darnage implies that exogenaus DNAcarcinogen adducts give rise to an incremental darnage which is expected to be proportional to the carcinogen dose at lowest Ievels. An increased tumor risk due to exposure to exogenaus genotoxic carcinogens could therefore be assessed in terms of the background DNA damage~ for instance in multiples of the mean Ievel or of the interindividual variability in a population.}, subject = {Toxikologie}, language = {en} } @article{MaierhoferFlunkertDittrichetal.2017, author = {Maierhofer, Anna and Flunkert, Julia and Dittrich, Marcus and M{\"u}ller, Tobias and Schindler, Detlev and Nanda, Indrajit and Haaf, Thomas}, title = {Analysis of global DNA methylation changes in primary human fibroblasts in the early phase following X-ray irradiation}, series = {PLoS ONE}, volume = {12}, journal = {PLoS ONE}, number = {5}, doi = {10.1371/journal.pone.0177442}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-170895}, pages = {e0177442}, year = {2017}, abstract = {Epigenetic alterations may contribute to the generation of cancer cells in a multi-step process of tumorigenesis following irradiation of normal body cells. Primary human fibroblasts with intact cell cycle checkpoints were used as a model to test whether X-ray irradiation with 2 and 4 Gray induces direct epigenetic effects (within the first cell cycle) in the exposed cells. ELISA-based fluorometric assays were consistent with slightly reduced global DNA methylation and hydroxymethylation, however the observed between-group differences were usually not significant. Similarly, bisulfite pyrosequencing of interspersed LINE-1 repeats and centromeric α-satellite DNA did not detect significant methylation differences between irradiated and non-irradiated cultures. Methylation of interspersed ALU repeats appeared to be slightly increased (one percentage point; p = 0.01) at 6 h after irradiation with 4 Gy. Single-cell analysis showed comparable variations in repeat methylation among individual cells in both irradiated and control cultures. Radiation-induced changes in global repeat methylation, if any, were much smaller than methylation variation between different fibroblast strains. Interestingly, α-satellite DNA methylation positively correlated with gestational age. Finally, 450K methylation arrays mainly targeting genes and CpG islands were used for global DNA methylation analysis. There were no detectable methylation differences in genic (promoter, 5' UTR, first exon, gene body, 3' UTR) and intergenic regions between irradiated and control fibroblast cultures. Although we cannot exclude minor effects, i.e. on individual CpG sites, collectively our data suggest that global DNA methylation remains rather stable in irradiated normal body cells in the early phase of DNA damage response.}, language = {en} } @article{OthmanNaseemAwadetal.2016, author = {Othman, Eman M. and Naseem, Muhammed and Awad, Eman and Dandekar, Thomas and Stopper, Helga}, title = {The Plant Hormone Cytokinin Confers Protection against Oxidative Stress in Mammalian Cells}, series = {PLoS One}, volume = {11}, journal = {PLoS One}, number = {12}, doi = {10.1371/journal.pone.0168386}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-147983}, pages = {e0168386}, year = {2016}, abstract = {Modulating key dynamics of plant growth and development, the effects of the plant hormone cytokinin on animal cells gained much attention recently. Most previous studies on cytokinin effects on mammalian cells have been conducted with elevated cytokinin concentration (in the μM range). However, to examine physiologically relevant dose effects of cytokinins on animal cells, we systematically analyzed the impact of kinetin in cultured cells at low and high concentrations (1nM-10μM) and examined cytotoxic and genotoxic conditions. We furthermore measured the intrinsic antioxidant activity of kinetin in a cell-free system using the Ferric Reducing Antioxidant Power assay and in cells using the dihydroethidium staining method. Monitoring viability, we looked at kinetin effects in mammalian cells such as HL60 cells, HaCaT human keratinocyte cells, NRK rat epithelial kidney cells and human peripheral lymphocytes. Kinetin manifests no antioxidant activity in the cell free system and high doses of kinetin (500 nM and higher) reduce cell viability and mediate DNA damage in vitro. In contrast, low doses (concentrations up to 100 nM) of kinetin confer protection in cells against oxidative stress. Moreover, our results show that pretreatment of the cells with kinetin significantly reduces 4-nitroquinoline 1-oxide mediated reactive oxygen species production. Also, pretreatment with kinetin retains cellular GSH levels when they are also treated with the GSH-depleting agent patulin. Our results explicitly show that low kinetin doses reduce apoptosis and protect cells from oxidative stress mediated cell death. Future studies on the interaction between cytokinins and human cellular pathway targets will be intriguing.}, language = {en} } @article{PetrusevaNaumenkoKuperetal.2021, author = {Petruseva, Irina and Naumenko, Natalia and Kuper, Jochen and Anarbaev, Rashid and Kappenberger, Jeannette and Kisker, Caroline and Lavrik, Olga}, title = {The Interaction Efficiency of XPD-p44 With Bulky DNA Damages Depends on the Structure of the Damage}, series = {Frontiers in Cell and Developmental Biology}, volume = {9}, journal = {Frontiers in Cell and Developmental Biology}, issn = {2296-634X}, doi = {10.3389/fcell.2021.617160}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-231806}, year = {2021}, abstract = {The successful elimination of bulky DNA damages via the nucleotide excision repair (NER) system is largely determined by the damage recognition step. This step consists of primary recognition and verification of the damage. The TFIIH helicase XPD plays a key role in the verification step during NER. To date, the mechanism of damage verification is not sufficiently understood and requires further detailed research. This study is a systematic investigation of the interaction of ctXPD (Chaetomium thermophilum) as well as ctXPD-ctp44 with model DNAs, which contain structurally different bulky lesions with previously estimated NER repair efficiencies. We have used ATPase and DNA binding studies to assess the interaction of ctXPD with damaged DNA. The result of the analysis of ctXPD-ctp44 binding to DNA containing fluorescent and photoactivatable lesions demonstrates the relationship between the affinity of XPD for DNAs containing bulky damages and the ability of the NER system to eliminate the damage. Photo-cross-linking of ctXPD with DNA probes containing repairable and unrepairable photoactivatable damages reveals differences in the DNA interaction efficiency in the presence and absence of ctp44. In general, the results obtained indicate the ability of ctXPD-ctp44 to interact with a damage and suggest a significant role for ctp44 subunit in the verification process.}, language = {en} } @article{ReimannStopperHintzsche2020, author = {Reimann, Hauke and Stopper, Helga and Hintzsche, Henning}, title = {Long-term fate of etoposide-induced micronuclei and micronucleated cells in Hela-H2B-GFP cells}, series = {Archives of Toxicology}, volume = {94}, journal = {Archives of Toxicology}, issn = {0340-5761}, doi = {10.1007/s00204-020-02840-0}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-235039}, pages = {3553-3561}, year = {2020}, abstract = {Micronuclei are small nuclear cellular structures containing whole chromosomes or chromosomal fragments. While there is a lot of information available about the origin and formation of micronuclei, less is known about the fate of micronuclei and micronucleated cells. Possible fates include extrusion, degradation, reincorporation and persistence. Live cell imaging was performed to quantitatively analyse the fates of micronuclei and micronucleated cells occurring in vitro. Imaging was conducted for up to 96 h in HeLa-H2B-GFP cells treated with 0.5, 1 and 2 µg/ml etoposide. While a minority of micronuclei was reincorporated into the main nucleus during mitosis, the majority of micronuclei persisted without any alterations. Degradation and extrusion were observed rarely or never. The presence of micronuclei affected the proliferation of the daughter cells and also had an influence on cell death rates. Mitotic errors were found to be clearly increased in micronucleus-containing cells. The results show that micronuclei and micronucleated cells can, although delayed in cell cycle, sustain for multiple divisions.}, language = {en} } @article{ReimannStopperPolaketal.2020, author = {Reimann, Hauke and Stopper, Helga and Polak, Thomas and Lauer, Martin and Herrmann, Martin J. and Deckert, J{\"u}rgen and Hintzsche, Henning}, title = {Micronucleus frequency in buccal mucosa cells of patients with neurodegenerative diseases}, series = {Scientific Reports}, volume = {10}, journal = {Scientific Reports}, doi = {10.1038/s41598-020-78832-y}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-231430}, year = {2020}, abstract = {Neurodegenerative diseases show an increase in prevalence and incidence, with the most prominent example being Alzheimer's disease. DNA damage has been suggested to play a role in the pathogenesis, but the exact mechanisms remain elusive. We enrolled 425 participants with and without neurodegenerative diseases and analyzed DNA damage in the form of micronuclei in buccal mucosa samples. In addition, other parameters such as binucleated cells, karyolytic cells, and karyorrhectic cells were quantified. No relevant differences in DNA damage and cytotoxicity markers were observed in patients compared to healthy participants. Furthermore, other parameters such as lifestyle factors and diseases were also investigated. Overall, this study could not identify a direct link between changes in buccal cells and neurogenerative diseases, but highlights the influence of lifestyle factors and diseases on the human buccal cytome.}, language = {en} } @article{ScherzadMeyerKleinsasseretal.2017, author = {Scherzad, Agmal and Meyer, Till and Kleinsasser, Norbert and Hackenberg, Stephan}, title = {Molecular Mechanisms of Zinc Oxide Nanoparticle-Induced Genotoxicity Short Running Title: Genotoxicity of ZnO NPs}, series = {Materials}, volume = {10}, journal = {Materials}, number = {12}, doi = {10.3390/ma10121427}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-169948}, pages = {1427}, year = {2017}, abstract = {Background: Zinc oxide nanoparticles (ZnO NPs) are among the most frequently applied nanomaterials in consumer products. Evidence exists regarding the cytotoxic effects of ZnO NPs in mammalian cells; however, knowledge about the potential genotoxicity of ZnO NPs is rare, and results presented in the current literature are inconsistent. Objectives: The aim of this review is to summarize the existing data regarding the DNA damage that ZnO NPs induce, and focus on the possible molecular mechanisms underlying genotoxic events. Methods: Electronic literature databases were systematically searched for studies that report on the genotoxicity of ZnO NPs. Results: Several methods and different endpoints demonstrate the genotoxic potential of ZnO NPs. Most publications describe in vitro assessments of the oxidative DNA damage triggered by dissoluted Zn2+ ions. Most genotoxicological investigations of ZnO NPs address acute exposure situations. Conclusion: Existing evidence indicates that ZnO NPs possibly have the potential to damage DNA. However, there is a lack of long-term exposure experiments that clarify the intracellular bioaccumulation of ZnO NPs and the possible mechanisms of DNA repair and cell survival.}, language = {en} } @article{SchuhmannEberleinMuelleretal.2018, author = {Schuhmann, Sarah and Eberlein, Uta and M{\"u}ller, Jessica and Scherthan, Harry and Lassmann, Michael}, title = {Correlation of the absorbed dose to the blood and DNA damage in leukocytes after internal ex-vivo irradiation of blood samples with Ra-224}, series = {EJNMMI Research}, volume = {8}, journal = {EJNMMI Research}, number = {77}, doi = {10.1186/s13550-018-0422-4}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-176593}, year = {2018}, abstract = {Background: Irradiation with α-particles creates densely packed damage tracks along particle trajectories in exposed cells, including complex DNA damage and closely spaced double-strand breaks (DSBs) in hit nuclei. Here, we investigated the correlation of the absorbed dose to the blood and the number of α-induced DNA damage tracks elicited in human blood leukocytes after ex-vivo in-solution exposure with Ra-224. The aim was to compare the data to previously published data on Ra-223 and to investigate differences in DNA damage induction between the two radium isotopes. Results: Blood samples from three healthy volunteers were exposed ex-vivo to six different concentrations of Ra-224 dichloride. Absorbed doses to the blood were calculated assuming local energy deposition of all α- and β-particles of the Ra-224 decay chain, ranging from 0 to 127 mGy. γ-H2AX + 53BP1 DNA damage co-staining and analysis was performed on ethanol-fixed leukocytes isolated from the irradiated blood samples. For damage quantification, α-induced DNA damage tracks and small γ-H2AX + 53BP1 DSB foci were enumerated in the exposed leukocytes. This revealed a linear relationship between the frequency of α-induced γ-H2AX damage tracks and the absorbed dose to the blood, while the frequency of small γ-H2AX + 53BP1 DSB foci indicative of β-irradiation was similar to baseline values. Conclusions: Our data provide a first estimation of the DNA damage induced by Ra-224 in peripheral blood mononuclear cells. A comparison with our previously published Ra-223 data suggests that there is no difference in the induction of radiation-induced DNA damage between the two radium isotopes due to their similar decay properties.}, language = {en} } @article{SchumannEberleinLapaetal.2021, author = {Schumann, S. and Eberlein, U. and Lapa, C. and M{\"u}ller, J. and Serfling, S. and Lassmann, M. and Scherthan, H.}, title = {α-Particle-induced DNA damage tracks in peripheral blood mononuclear cells of [\(^{223}\)Ra]RaCl\(_{2}\)-treated prostate cancer patients}, series = {European Journal of Nuclear Medicine and Molecular Imaging}, volume = {48}, journal = {European Journal of Nuclear Medicine and Molecular Imaging}, number = {9}, issn = {1619-7089}, doi = {10.1007/s00259-020-05170-6}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-265462}, pages = {2761-2770}, year = {2021}, abstract = {Purpose One therapy option for prostate cancer patients with bone metastases is the use of [\(^{223}\)Ra]RaCl\(_{2}\). The α-emitter \(^{223}\)Ra creates DNA damage tracks along α-particle trajectories (α-tracks) in exposed cells that can be revealed by immunofluorescent staining of γ-H2AX+53BP1 DNA double-strand break markers. We investigated the time- and absorbed dose-dependency of the number of α-tracks in peripheral blood mononuclear cells (PBMCs) of patients undergoing their first therapy with [\(^{223}\)Ra]RaCl\(_{2}\). Methods Multiple blood samples from nine prostate cancer patients were collected before and after administration of [\(^{223}\)Ra]RaCl\(_{2}\), up to 4 weeks after treatment. γ-H2AX- and 53BP1-positive α-tracks were microscopically quantified in isolated and immuno-stained PBMCs. Results The absorbed doses to the blood were less than 6 mGy up to 4 h after administration and maximally 16 mGy in total. Up to 4 h after administration, the α-track frequency was significantly increased relative to baseline and correlated with the absorbed dose to the blood in the dose range < 3 mGy. In most of the late samples (24 h - 4 weeks after administration), the α-track frequency remained elevated. Conclusion The γ-H2AX+53BP1 assay is a potent method for detection of α-particle-induced DNA damages during treatment with or after accidental incorporation of radionuclides even at low absorbed doses. It may serve as a biomarker discriminating α- from β-emitters based on damage geometry.}, language = {en} } @article{SchuppStopperHeidland2016, author = {Schupp, Nicole and Stopper, Helga and Heidland, August}, title = {DNA Damage in Chronic Kidney Disease: Evaluation of Clinical Biomarkers}, series = {Oxidative Medicine and Cellular Longevity}, volume = {2016}, journal = {Oxidative Medicine and Cellular Longevity}, number = {3592042}, doi = {10.1155/2016/3592042}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-166569}, year = {2016}, abstract = {Patients with chronic kidney disease (CKD) exhibit an increased cancer risk compared to a healthy control population. To be able to estimate the cancer risk of the patients and to assess the impact of interventional therapies thereon, it is of particular interest to measure the patients' burden of genomic damage. Chromosomal abnormalities, reduced DNA repair, and DNA lesions were found indeed in cells of patients with CKD. Biomarkers for DNA damage measurable in easily accessible cells like peripheral blood lymphocytes are chromosomal aberrations, structural DNA lesions, and oxidatively modified DNA bases. In this review the most common methods quantifying the three parameters mentioned above, the cytokinesis-block micronucleus assay, the comet assay, and the quantification of 8-oxo-7,8-dihydro-2′-deoxyguanosine, are evaluated concerning the feasibility of the analysis and regarding the marker's potential to predict clinical outcomes.}, language = {en} } @article{TrifaultMamontovaBurger2022, author = {Trifault, Barbara and Mamontova, Victoria and Burger, Kaspar}, title = {In vivo proximity labeling of nuclear and nucleolar proteins by a stably expressed, DNA damage-responsive NONO-APEX2 fusion protein}, series = {Frontiers in Molecular Biosciences}, volume = {9}, journal = {Frontiers in Molecular Biosciences}, issn = {2296-889X}, doi = {10.3389/fmolb.2022.914873}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-276707}, year = {2022}, abstract = {Cellular stress can induce DNA lesions that threaten the stability of genes. The DNA damage response (DDR) recognises and repairs broken DNA to maintain genome stability. Intriguingly, components of nuclear paraspeckles like the non-POU domain containing octamer-binding protein (NONO) participate in the repair of DNA double-strand breaks (DSBs). NONO is a multifunctional RNA-binding protein (RBP) that facilitates the retention and editing of messenger (m)RNA as well as pre-mRNA processing. However, the role of NONO in the DDR is poorly understood. Here, we establish a novel human U2OS cell line that expresses NONO fused to the engineered ascorbate peroxidase 2 (U2OS:NONO-APEX2-HA). We show that NONO-APEX2-HA accumulates in the nucleolus in response to DNA damage. Combining viability assays, subcellular localisation studies, coimmunoprecipitation experiments and in vivo proximity labeling, we demonstrate that NONO-APEX2-HA is a stably expressed fusion protein that mimics endogenous NONO in terms of expression, localisation and bona fide interactors. We propose that in vivo proximity labeling in U2OS:NONO-APEX2-HA cells is capable for the assessment of NONO interactomes by downstream assays. U2OS:NONO-APEX2-HA cells will likely be a valuable resource for the investigation of NONO interactome dynamics in response to DNA damage and other stimuli.}, language = {en} } @article{WinkelbeinerWandtEbertetal.2020, author = {Winkelbeiner, Nicola and Wandt, Viktoria K. and Ebert, Franziska and Lossow, Kristina and Bankoglu, Ezgi E. and Martin, Maximilian and Mangerich, Aswin and Stopper, Helga and Bornhorst, Julia and Kipp, Anna P. and Schwerdtle, Tanja}, title = {A multi-endpoint approach to base excision repair incision activity augmented by PARylation and DNA damage levels in mice: impact of sex and age}, series = {International Journal of Molecular Sciences}, volume = {21}, journal = {International Journal of Molecular Sciences}, number = {18}, issn = {1422-0067}, doi = {10.3390/ijms21186600}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-285706}, year = {2020}, abstract = {Investigation of processes that contribute to the maintenance of genomic stability is one crucial factor in the attempt to understand mechanisms that facilitate ageing. The DNA damage response (DDR) and DNA repair mechanisms are crucial to safeguard the integrity of DNA and to prevent accumulation of persistent DNA damage. Among them, base excision repair (BER) plays a decisive role. BER is the major repair pathway for small oxidative base modifications and apurinic/apyrimidinic (AP) sites. We established a highly sensitive non-radioactive assay to measure BER incision activity in murine liver samples. Incision activity can be assessed towards the three DNA lesions 8-oxo-2'-deoxyguanosine (8-oxodG), 5-hydroxy-2'-deoxyuracil (5-OHdU), and an AP site analogue. We applied the established assay to murine livers of adult and old mice of both sexes. Furthermore, poly(ADP-ribosyl)ation (PARylation) was assessed, which is an important determinant in DDR and BER. Additionally, DNA damage levels were measured to examine the overall damage levels. No impact of ageing on the investigated endpoints in liver tissue were found. However, animal sex seems to be a significant impact factor, as evident by sex-dependent alterations in all endpoints investigated. Moreover, our results revealed interrelationships between the investigated endpoints indicative for the synergetic mode of action of the cellular DNA integrity maintaining machinery.}, language = {en} }