TY - JOUR A1 - Pagáčová, Eva A1 - Štefančíková, Lenka A1 - Schmidt-Kaler, Franz A1 - Hildenbrand, Georg A1 - Vičar, Tomáš A1 - Depeš, Daniel A1 - Lee, Jin-Ho A1 - Bestvater, Felix A1 - Lacombe, Sandrine A1 - Porcel, Erika A1 - Roux, Stéphane A1 - Wenz, Frederik A1 - Kopecna, Olga A1 - Falková, Iva A1 - Hausmann, Michael A1 - Falk, Martin T1 - Challenges and Contradictions of Metal Nano-Particle Applications for Radio-Sensitivity Enhancement in Cancer Therapy JF - International Journal of Molecular Sciences N2 - From the very beginnings of radiotherapy, a crucial question persists with how to target the radiation effectiveness into the tumor while preserving surrounding tissues as undamaged as possible. One promising approach is to selectively pre-sensitize tumor cells by metallic nanoparticles. However, though the “physics” behind nanoparticle-mediated radio-interaction has been well elaborated, practical applications in medicine remain challenging and often disappointing because of limited knowledge on biological mechanisms leading to cell damage enhancement and eventually cell death. In the present study, we analyzed the influence of different nanoparticle materials (platinum (Pt), and gold (Au)), cancer cell types (HeLa, U87, and SKBr3), and doses (up to 4 Gy) of low-Linear Energy Transfer (LET) ionizing radiation (γ- and X-rays) on the extent, complexity and reparability of radiation-induced γH2AX + 53BP1 foci, the markers of double stand breaks (DSBs). Firstly, we sensitively compared the focus presence in nuclei during a long period of time post-irradiation (24 h) in spatially (three-dimensionally, 3D) fixed cells incubated and non-incubated with Pt nanoparticles by means of high-resolution immunofluorescence confocal microscopy. The data were compared with our preliminary results obtained for Au nanoparticles and recently published results for gadolinium (Gd) nanoparticles of approximately the same size (2–3 nm). Next, we introduced a novel super-resolution approach—single molecule localization microscopy (SMLM)—to study the internal structure of the repair foci. In these experiments, 10 nm Au nanoparticles were used that could be also visualized by SMLM. Altogether, the data show that different nanoparticles may or may not enhance radiation damage to DNA, so multi-parameter effects have to be considered to better interpret the radiosensitization. Based on these findings, we discussed on conclusions and contradictions related to the effectiveness and presumptive mechanisms of the cell radiosensitization by nanoparticles. We also demonstrate that SMLM offers new perspectives to study internal structures of repair foci with the goal to better evaluate potential differences in DNA damage patterns. KW - Krebs, Medizin KW - Strahlentherapie Y1 - 2019 U6 - https://doi.org/https://doi.org/10.3390/ijms20030588 SN - 1422-0067 VL - 20 IS - 3 PB - MDPI AG ER - TY - JOUR A1 - Hausmann, Michael A1 - Neitzel, Charlotte A1 - Bobkova, Elizaveta A1 - Nagel, David A1 - Hofmann, Andreas A1 - Chramko, Tatyana A1 - Smirnova, Elena A1 - Kopecna, Olga A1 - Pagáčová, Eva A1 - Boreyko, Alla A1 - Krasavin, Evgeny A1 - Falkova, Iva A1 - Heermann, Dieter W. A1 - Pilarczyk, Götz A1 - Hildenbrand, Georg A1 - Bestvater, Felix A1 - Falk, Martin T1 - Single Molecule Localization Microscopy Analyses of DNA-Repair Foci and Clusters Detected Along Particle Damage Tracks JF - Frontiers in Physics KW - Krebszelle KW - Strahlentherapie KW - Genom KW - Zellkern Y1 - 2020 U6 - https://doi.org/https://doi.org/10.3389/fphy.2020.578662 SN - 2296-424X VL - 8 PB - Frontiers Media SA ER - TY - JOUR A1 - Dobešová, Lucie A1 - Gier, Theresa A1 - Kopecna, Olga A1 - Pagáčová, Eva A1 - Vičar, Tomáš A1 - Bestvater, Felix A1 - Toufar, Jiří A1 - Bačíková, Alena A1 - Kopel, Pavel A1 - Fedr, Radek A1 - Hildenbrand, Georg A1 - Falková, Iva A1 - Falk, Martin A1 - Hausmann, Michael T1 - Incorporation of Low Concentrations of Gold Nanoparticles: Complex Effects on Radiation Response and Fate of Cancer Cells JF - Pharmaceutics N2 - (1) Background: In oncology research, a long-standing discussion exists about pros and cons of metal nanoparticle-enhanced radiotherapy and real mechanisms behind the tumor cell response to irradiation (IR) in presence of gold nanoparticles (GNPs). A better understanding of this response is, however, necessary to develop more efficient and safety nanoparticle (NP) types designed to disturb specific processes in tumor cells. (2) Aims and Methods: We combined 3D confocal microscopy and super-resolution single molecule localization microscopy (SMLM) to analyze, at the multiscale, the early and late effects of 10 nm-GNPs on DNA double strand break (DSB) induction and repair in tumor cells exposed to different doses of photonic low-LET (linear energy transfer) radiation. The results were correlated to different aspects of short and long-term cell viability. SkBr3 breast cancer cells (selected for the highest incidence of this cancer type among all cancers in women, and because most breast tumors are treated with IR) were incubated with low concentrations of GNPs and irradiated with 60Co γ-rays or 6 MV X-rays. In numerous post-irradiation (PI) times, ranging from 0.5 to 24 h PI, the cells were spatially (3D) fixed and labeled with specific antibodies against γH2AX, 53BP1 and H3K9me3. The extent of DSB induction, multi-parametric micro- and nano-morphology of γH2AX and 53BP1 repair foci, DSB repair kinetics, persistence of unrepaired DSBs, nanoscale clustering of γH2AX and nanoscale (hetero)chromatin re-organization were measured by means of the mentioned microscopy techniques in dependence of radiation dose and GNP concentration. (3) Results: The number of γH2AX/53BP1 signals increased after IR and an additional increase was observed in GNP-treated (GNP(+)) cells compared to untreated controls. However, this phenomenon reflected slight expansion of the G2-phase cell subpopulation in irradiated GNP(+) specimens instead of enhanced DNA damage induction by GNPs. This statement is further supported by some micro- and nano-morphological parameters of γH2AX/53BP1 foci, which slightly differed for cells irradiated in absence or presence of GNPs. At the nanoscale, Ripley’s distance frequency analysis of SMLM signal coordinate matrices also revealed relaxation of heterochromatin (H3K9me3) clusters upon IR. These changes were more prominent in presence of GNPs. The slight expansion of radiosensitive G2 cells correlated with mostly insignificant but systematic decrease in post-irradiation survival of GNP(+) cells. Interestingly, low GNP concentrations accelerated DSB repair kinetics; however, the numbers of persistent γH2AX/53BP1 repair foci were slightly increased in GNP(+) cells. (4) Conclusions: Low concentrations of 10-nm GNPs enhanced the G2/M cell cycle arrest and the proportion of radiosensitive G2 cells, but not the extent of DNA damage induction. GNPs also accelerated DSB repair kinetics and slightly increased presence of unrepaired γH2AX/53BP1 foci at 24 h PI. GNP-mediated cell effects correlated with slight radiosensitization of GNP(+) specimens, significant only for the highest radiation dose tested (4 Gy). KW - Strahlentherapie KW - Krebs, Medizin KW - Tumorzelle KW - Gold KW - Nanopartikel Y1 - 2022 U6 - https://doi.org/https://doi.org/10.3390/pharmaceutics14010166 SN - 1999-4923 VL - 14 IS - 1 PB - MDPI AG ER - TY - JOUR A1 - Bobkova, Elizaveta A1 - Depes, Daniel A1 - Lee, Jin-Ho A1 - Jezkova, Lucie A1 - Falkova, Iva A1 - Pagacova, Eva A1 - Kopecna, Olga A1 - Zadneprianetc, Mariia A1 - Bacikova, Alena A1 - Kulikova, Elena A1 - Smirnova, Elena A1 - Bulanova, Tatiana A1 - Boreyko, Alla A1 - Krasavin, Evgeny A1 - Wenz, Frederik A1 - Bestvater, Felix A1 - Hildenbrand, Georg A1 - Hausmann, Michael A1 - Falk, Martin T1 - Recruitment of 53BP1 Proteins for DNA Repair and Persistence of Repair Clusters Differ for Cell Types as Detected by Single Molecule Localization Microscopy JF - International Journal of Molecular Sciences N2 - DNA double stranded breaks (DSBs) are the most serious type of lesions introduced into chromatin by ionizing radiation. During DSB repair, cells recruit different proteins to the damaged sites in a manner dependent on local chromatin structure, DSB location in the nucleus, and the repair pathway entered. 53BP1 is one of the important players participating in repair pathway decision of the cell. Although many molecular biology details have been investigated, the architecture of 53BP1 repair foci and its development during the post-irradiation time, especially the period of protein recruitment, remains to be elucidated. Super-resolution light microscopy is a powerful new tool to approach such studies in 3D-conserved cell nuclei. Recently, we demonstrated the applicability of single molecule localization microscopy (SMLM) as one of these highly resolving methods for analyses of dynamic repair protein distribution and repair focus internal nano-architecture in intact cell nuclei. In the present study, we focused our investigation on 53BP1 foci in differently radio-resistant cell types, moderately radio-resistant neonatal human dermal fibroblasts (NHDF) and highly radio-resistant U87 glioblastoma cells, exposed to high-LET 15N-ion radiation. At given time points up to 24 h post irradiation with doses of 1.3 Gy and 4.0 Gy, the coordinates and spatial distribution of fluorescently tagged 53BP1 molecules was quantitatively evaluated at the resolution of 10–20 nm. Clusters of these tags were determined as sub-units of repair foci according to SMLM parameters. The formation and relaxation of such clusters was studied. The higher dose generated sufficient numbers of DNA breaks to compare the post-irradiation dynamics of 53BP1 during DSB processing for the cell types studied. A perpendicular (90°) irradiation scheme was used with the 4.0 Gy dose to achieve better separation of a relatively high number of particle tracks typically crossing each nucleus. For analyses along ion-tracks, the dose was reduced to 1.3 Gy and applied in combination with a sharp angle irradiation (10° relative to the cell plane). The results reveal a higher ratio of 53BP1 proteins recruited into SMLM defined clusters in fibroblasts as compared to U87 cells. Moreover, the speed of foci and thus cluster formation and relaxation also differed for the cell types. In both NHDF and U87 cells, a certain number of the detected and functionally relevant clusters remained persistent even 24 h post irradiation; however, the number of these clusters again varied for the cell types. Altogether, our findings indicate that repair cluster formation as determined by SMLM and the relaxation (i.e., the remaining 53BP1 tags no longer fulfill the cluster definition) is cell type dependent and may be functionally explained and correlated to cell specific radio-sensitivity. The present study demonstrates that SMLM is a highly appropriate method for investigations of spatiotemporal protein organization in cell nuclei and how it influences the cell decision for a particular repair pathway at a given DSB site. KW - Genom KW - Krebs, Medizin KW - Strahlentherapie Y1 - 2018 U6 - https://doi.org/https://doi.org/10.3390/ijms19123713 SN - 1422-0067 VL - 19 IS - 12 PB - MDPI AG ER -