DNA damage response in a 2D-culture model by diffusing alpha-emitters radiation therapy (Alpha-DaRT).

Diffusing alpha-emitters radiation therapy (Alpha-DaRT) is a unique method, in which interstitial sources carrying 224Ra release a chain of short-lived daughter atoms from their surface. Although DNA damage response (DDR) is crucial to inducing cell death after irradiation, how the DDR occurs during Alpha-DaRT treatment has not yet been explored. In this study, we temporo-spatially characterized DDR such as kinetics of DNA double-strand breaks (DSBs) and cell cycle, in two-dimensional (2D) culture conditions qualitatively mimicking Alpha-DaRT treatments, by employing HeLa cells expressing the Fucci cell cycle-visualizing system. The distribution of the alpha-particle pits detected by a plastic nuclear track detector, CR-39, strongly correlated with γH2AX staining, a marker of DSBs, around the 224Ra source, but the area of G2 arrested cells was more widely spread 24 h from the start of the exposure. Thereafter, close time-lapse observation revealed varying cell cycle kinetics, depending on the distance from the source. A medium containing daughter nuclides prepared from 224Ra sources allowed us to estimate the radiation dose after 24 h of exposure, and determine surviving fractions. The present experimental model revealed for the first time temporo-spatial information of DDR occurring around the source in its early stages.

Induction of Chromosomal Aberrations after Exposure to the Auger Electron Emitter Iodine-125, the ß--emitter Tritium and Cesium-137 γ rays.

High-LET-type cell survival curves have been observed in cells that were allowed to incorporate 125I-UdR into their DNA. Incorporation of tritiated thymidine into the DNA of cells has also been shown to result in an increase in relative biological effectiveness in cell survival experiments, but the increase is smaller than observed after incorporation of 125I-UdR. These findings are explained in the literature by the overall complexity of the induced DNA damage resulting from energies of the ejected electron(s) during the decay of 3H and 125I. Chromosomal aberrations (CA) are defined as morphological or structural changes of one or more chromosomes, and can be induced by ionizing radiation. Whether the number of CA is associated with the linear energy transfer (LET) of the radiation and/or the actual complexity of the induced DNA double-strand breaks (DSB) remains elusive. In this study, we investigated whether DNA lesions induced at different cell cycle stages and by different radiation types [Auger-electrons (125I), ß- particles (3H), or γ radiation (137Cs)] have an impact on the number of CA induced after induction of the same number of DSB as determined by the γ-H2AX foci assay. Cells were synchronized and pulse-labeled in S phase with low activities of 125I-UdR or tritiated thymidine. For decay accumulation, cells were cryopreserved either after pulse-labeling in S phase or after progression to G2/M or G1 phase. Experiments with γ irradiation (137Cs) were performed with synchronized and cryopreserved cells in S, G2/M or G1 phase. After thawing, a CA assay was performed. All experiments were performed after a similar number of DSB were induced. CA induction after 125I-UdR was incorporated was 2.9-fold and 1.7-fold greater compared to exposure to γ radiation and radiation from incorporated tritiated thymidine, respectively, when measured in G2/M cells. In addition, measurement of CA in G2/M cells after incorporation of 125I-UdR was 2.5-fold greater when compared to cells in G1 phase. In contrast, no differences were observed between the three radiation qualities with respect to exposure after cryopreservation in S or G1 phase. The data indicate that the 3D organization of replicated DNA in G2/M cells seems to be more sensitive to induction of more complex DNA lesions compared to the DNA architecture in S or G1 cells. Whether this is due to the DNA organization itself or differences in DNA repair capability remains unclear.

Single-Cell Radiation Response Scoring with the Deep Learning Algorithm CeCILE 2.0.

External stressors, such as ionizing radiation, have massive effects on life, survival, and the ability of mammalian cells to divide. Different types of radiation have different effects. In order to understand these in detail and the underlying mechanisms, it is essential to study the radiation response of each cell. This allows abnormalities to be characterized and laws to be derived. Tracking individual cells over several generations of division generates large amounts of data that can no longer be meaningfully analyzed by hand. In this study, we present a deep-learning-based algorithm, CeCILE (Cell classification and in vitro lifecycle evaluation) 2.0, that can localize, classify, and track cells in live cell phase-contrast videos. This allows conclusions to be drawn about the viability of the cells, the cell cycle, cell survival, and the influence of X-ray radiation on these. Furthermore, radiation-specific abnormalities during division could be characterized. In summary, CeCILE 2.0 is a powerful tool to characterize and quantify the cellular response to external stressors such as radiation and to put individual responses into a larger context. To the authors knowledge, this is the first algorithm with a fully integrated workflow that is able to do comprehensive single-cell and cell composite analysis, allowing them to draw conclusions on cellular radiation response.

Understanding radiation response and cell cycle variation in brain tumour cells using Raman spectroscopy.

Radiation therapy is currently utilised in the treatment of approximately 50% of cancer patients. A move towards patient tailored radiation therapy would help to improve the treatment outcome for patients as the inter-patient and intra-patient heterogeneity of cancer leads to large differences in treatment responses. In radiation therapy, a typical treatment outcome is cell cycle arrest which leads to cell cycle synchronisation. As treatment is typically given over multiple fractions it is important to understand how variation in the cell cycle can affect treatment response. Raman spectroscopy has previously been assessed as a method for monitoring radiation response in cancer cells and has shown promise in detecting the subtle biochemical changes following radiation exposure. This study evaluated Raman spectroscopy as a potential tool for monitoring cellular response to radiation in synchronised versus unsynchronised UVW human glioma cells in vitro. Specifically, it was hypothesised that the UVW cells would demonstrate a greater radiation resistance if the cell cycle phase of the cells was synchronised to the G1/S boundary prior to radiation exposure. Here we evaluated whether Raman spectroscopy, combined with cell cycle analysis and DNA damage and repair analysis (γ-H2AX assay), could discriminate the subtle cellular changes associated with radiation response. Raman spectroscopy combined with principal component analysis (PCA) was able to show the changes in radiation response over 24 hours following radiation exposure. Spectral changes were assigned to variations in protein, specifically changes in protein signals from amides as well as changes in lipid expression. A different response was observed between cells synchronised in the cell cycle and unsynchronised cells. After 24 hours following irradiation, the unsynchronised cells showed greater spectral changes compared to the synchronised cells demonstrating that the cell cycle plays an important role in the radiation resistance or sensitivity of the UVW cells, and that radiation resistance could be induced by controlling the cell cycle. One of the main aims of cancer treatment is to stop the proliferation of cells by controlling or halting progression through the cell cycle, thereby highlighting the importance of controlling the cell cycle when studying the effects of cancer treatments such as radiation therapy. Raman spectroscopy has been shown to be a useful tool for evaluating the changes in radiation response when the cell cycle phase is controlled and therefore highlighting its potential for assessing radiation response and resistance.

Transcriptional Reprogramming Regulates Tumor Cell Survival in Response to Ionizing Radiation: a Role of p53.

Senexin B, a non-toxic selective inhibitor of cyclin-dependent protein kinases 8 and 19 (CDK8 and CDK19), in combination with γ-photon irradiation in doses of 2-10 Gy increased the death of colon adenocarcinoma cell line HCT116 (intact p53) in a logarithmically growing culture, which was accompanied by the prevention of cell cycle arrest and a decrease of "senescence" phenotype. The effect of senexin B in cells with intact p53 is similar to that of Tp53 gene knockout: irradiated HCT116p53KO cells passed through the interphase and died independently of senexin B. The inhibitor reduced the ability of cells to colony formation in response to irradiation; p53 status did not affect the effectiveness of the combination of radiation and senexin B. Thus, the CDK8/19 inhibitor senexin B increased cell sensitivity to radiotherapy by mechanisms dependent and independent of p53 status.

DAP3-mediated cell cycle regulation and its association with radioresistance in human lung adenocarcinoma cell lines.

Mitochondria play important roles in the cellular response to various types of stress, including that triggered by ionizing radiation. We have previously reported that the mitochondrial ribosomal protein death-associated protein 3 (DAP3) regulates the radioresistance of human lung adenocarcinoma (LUAD) cell lines A549 and H1299. However, the underlying mechanism of this regulation remains to be elucidated. To this end, we have herein investigated the role of DAP3 in the cell cycle regulation after irradiation. Notably, the DAP3 knockdown attenuated the radiation-induced increase of the G2/M cell population. Furthermore, western blotting analysis has revealed that the DAP3 knockdown decreased the expression of proteins related to the G2/M arrest, such as those of the phosphorylated cdc2 (Tyr15) and the phosphorylated checkpoint kinase 1 (Ser296), in irradiated A549 cells and H1299 cells. Moreover, by using a chk1 inhibitor, we were able to demonstrate that chk1 is involved in the radiation-induced G2/M arrest in both A549 and H1299 cells. Notably, the chk1 inhibitor was able to enhance the radiosensitivity of H1299 cells, while both chk1 inhibitor-abolished G2 arrest and inhibition of chk2-mediated events such as downregulation of radiation-induced p21 expression were required for enhancing radiosensitivity of A549 cells. Collectively, our findings reveal a novel role of DAP3 to regulate G2/M arrest through pchk1 in irradiated LUAD cells and suggest that chk1-mediated G2/M arrest regulates the radioresistance of H1299 cells, whereas both the chk1-mediated G2/M arrest and the chk2-mediated events contribute to the radioresistance of A549 cells.

Long-term p21 and p53 dynamics regulate the frequency of mitosis events and cell cycle arrest following radiation damage.

Radiation exposure of healthy cells can halt cell cycle temporarily or permanently. In this work, we analyze the time evolution of p21 and p53 from two single cell datasets of retinal pigment epithelial cells exposed to several levels of radiation, and in particular, the effect of radiation on cell cycle arrest. Employing various quantification methods from signal processing, we show how p21 levels, and to a lesser extent p53 levels, dictate whether the cells are arrested in their cell cycle and how frequently these mitosis events are likely to occur. We observed that single cells exposed to the same dose of DNA damage exhibit heterogeneity in cellular outcomes and that the frequency of cell division is a more accurate monitor of cell damage rather than just radiation level. Finally, we show how heterogeneity in DNA damage signaling is manifested early in the response to radiation exposure level and has potential to predict long-term fate.

Determination of Clonogenic Radiosensitivity of HeLa Cells in Early and Late G1 Phases.

BACKGROUND/AIM: Using a fluorescent ubiquitination-based cell cycle indicator (Fucci), we recently reported that post irradiation of HeLa cells, micronuclei frequency increased in the early G1 phase in comparison with that in the late G1 phase. This is inconsistent with the results of well-recognized studies that used clonogenic assays. In this study, we determined radiosensitivity of the cells using a clonogenic assay by making the best use of the Fucci property, while simultaneously characterizing cell cycle kinetics and DNA damage responses. MATERIALS AND METHODS: Early and late G1 phase cell fractions were isolated using a cell sorter by exploiting the different red fluorescence intensities of Fucci. Radiosensitivity was determined by the colony formation assay. Time-lapse imaging and immunostaining were performed to analyze cell cycle kinetics and DNA damage. RESULTS: Late G1 cells were more radioresistant than early G1 cells. Cells irradiated in the early and late G1 phases induced G2 arrest, while the latter demonstrated a significantly longer duration of G2 arrest. This difference became more evident as the radiation dose increased. Furthermore, 16 h after irradiation, a greater number of γH2AX foci remained in cells irradiated in the early G1 phase than in those irradiated in the late G1 phase. CONCLUSION: HeLa cells in the late G1 phase are more radioresistant than those in the early G1 phase, presumably because DNA damage is efficiently repaired during a longer G2 arrest in late G1 cells.

Differential molecular response in mice and human thymocytes exposed to a combined-dose radiation regime.

In the quest for more effective radiation treatment options that can improve both cell killing and healthy tissue recovery, combined radiation therapies are lately in the spotlight. The molecular response to a combined radiation regime where exposure to an initial low dose (priming dose) of ionizing radiation is administered prior to a subsequent higher radiation dose (challenging dose) after a given latency period have not been thoroughly explored. In this study we report on the differential response to either a combined radiation regime or a single challenging dose both in mouse in vivo and in human ex vivo thymocytes. A differential cell cycle response including an increase in the subG1 fraction on cells exposed to the combined regime was found. Together with this, a differential protein expression profiling in several pathways including cell cycle control (ATM, TP53, p21CDKN1A), damage response (γH2AX) and cell death pathways such as apoptosis (Cleaved Caspase-3, PARP1, PKCδ and H3T45ph) and ferroptosis (xCT/GPX4) was demonstrated. This study also shows the epigenetic regulation following a combined regime that alters the expression of chromatin modifiers such as DNMTs (DNMT1, DNMT2, DNMT3A, DNMT3B, DNMT3L) and glycosylases (MBD4 and TDG). Furthermore, a study of the underlying cellular status six hours after the priming dose alone showed evidence of retained modifications on the molecular and epigenetic pathways suggesting that the priming dose infers a "radiation awareness phenotype" to the thymocytes, a sensitization key to the differential response seen after the second hit with the challenging dose. These data suggest that combined-dose radiation regimes could be more efficient at making cells respond to radiation and it would be interesting to further investigate how can these schemes be of use to potential new radiation therapies.

Human mesenchymal stromal cells maintain their stem cell traits after high-LET particle irradiation - Potential implications for particle radiotherapy and manned space missions.

The influence of high-linear energy transfer (LET) particle radiation on the functionalities of mesenchymal stromal cells (MSCs) is largely unknown. Here, we analyzed the effects of proton (1H), helium (4He), carbon (12C) and oxygen (16O) ions on human bone marrow-MSCs. Cell cycle distribution and apoptosis induction were examined by flow cytometry, and DNA damage was quantified using γH2AX immunofluorescence and Western blots. Relative biological effectiveness values of MSCs amounted to 1.0-1.1 for 1H, 1.7-2.3 for 4He, 2.9-3.4 for 12C and 2.6-3.3 for 16O. Particle radiation did not alter the MSCs' characteristic surface marker pattern, and MSCs maintained their multi-lineage differentiation capabilities. Apoptosis rates ranged low for all radiation modalities. At 24 h after irradiation, particle radiation-induced ATM and CHK2 phosphorylation as well as γH2AX foci numbers returned to baseline levels. The resistance of human MSCs to high-LET irradiation suggests that MSCs remain functional after exposure to moderate doses of particle radiation as seen in normal tissues after particle radiotherapy or during manned space flights. In the future, in vivo models focusing on long-term consequences of particle irradiation on the bone marrow niche and MSCs are needed.

AZD3759 enhances radiation effects in non-small-cell lung cancer by a synergistic blockade of epidermal growth factor receptor and Janus kinase-1.

AZD3759 is a novel epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor (TKI) on the basis of gefitinib and has been proven to enter the central nervous system. Although the promising antitumor effects of AZD3759 on non-small cell lung cancer (NSCLC) have been demonstrated in clinical trials, the regulatory effects of this inhibitor on the antitumor efficacy of radiation (RA) are unclear. The present study aimed to compare the effects of AZD3759 and osimertinib on RA efficacy in NSCLC and explore the potential mechanism of action of AZD3759. We found that the survival in RA-treated NSCLC cells was significantly decreased by treatment with 500 nM AZD3759 and osimertinib at the RA dosage of 8 Gy. The apoptotic rate, cell cycle arrest, and DNA damage in RA-treated NSCLC cells and brain metastasis in RA-treated xenograft nude mice were significantly enhanced by the co-administration of AZD3759 and osimertinib, respectively. In addition, AZD3759 showed a significantly stronger efficacy than osimertinib did. Mechanistically, the receptor tyrosine kinase signaling antibody array revealed that Janus kinase-1 (JAK1) was specifically inhibited by AZD3759, but not by osimertinib. The effects of AZD3759 on RA efficacy in PC-9 cells and in a brain metastasis animal model were significantly abolished by the overexpression of JAK1. Collectively, our results suggested that AZD3759 promoted RA antitumor effects in NSCLC by synergistic blockade of EGFR and JAK1.

Antifungal Activity of a Neodymium-Doped Yttrium Aluminum Garnet 1,064-Nanometer Laser against Sporothrix globosa by Inducing Apoptosis and Pyroptosis via the NLRP3/Caspase-1 Signaling Pathway: In Vitro and In Vivo Study.

Sporotrichosis is a deep fungal infection caused by Sporothrix species. Currently, itraconazole is the main treatment, but fungal resistance, adverse effects, and drug interactions remain major concerns, especially in patients with immune dysfunction. Therefore, an alternative treatment is greatly in demand. This animal study aimed to investigate the inhibitory effect of neodymium-doped yttrium aluminum garnet (Nd:YAG) 1,064-nm laser treatment on Sporothrix globosa and to explore whether it happens through regulation of the Nod-like receptor thermoprotein domain-related protein 3 (NLRP3)/caspase-1 pyroptosis and apoptosis pathway. After laser irradiation, a series of studies, including assays of viability (using the cell counting kit-8 [CCK-8]), morphological structure changes, reactive oxygen species (ROS) accumulation, mitochondrial membrane potential, oxidative stress, cell cycle progression, and metacaspase activation, were conducted to estimate the effect of Nd:YAG 1,064-nm laser treatment on Sporothrix globosa cell apoptosis in vitro. For in vivo studies, mice were infected with S. globosa and then treated with laser or itraconazole, and their footpad skin lesions and the changes in the histology of tissue samples were compared. In addition, changes in the levels of NLRP3, caspase-1, and caspase-3 were assessed by immunohistochemistry, while the levels of interleukin 17 (IL-17), interferon gamma (IFN-γ), and transforming growth factor ß1 (TGF-ß1) in peripheral blood were tested by enzyme-linked immunosorbent assay (ELISA). The in vitro growth of S. globosa was inhibited and apoptosis was observed after laser treatment. According to the in vivo studies, the efficacy of the laser treatment was similar to that of itraconazole. Moreover, the NLRP3/caspase-1 pyroptosis pathway was activated, with a Th1/Th17 cell response, and the expression of caspase-3 was also upregulated. Nd:YAG 1,064-nm laser treatment can effectively inhibit the growth of S. globosa by activating fungal apoptosis and pyroptosis through the NLRP3/caspase-1 pathway. Therefore, Nd:YAG 1,064-nm laser irradiation is an alternative for sporotrichosis therapy. IMPORTANCE Nd:YAG 1,064-nm laser irradiation is a useful alternative for the treatment of sporotrichosis, especially in patients with liver dysfunction, pregnant women, and children, for whom the administration of antifungal drugs is not suitable. It may improve the overall treatment effect by shortening the duration of antifungal treatment and reducing tissue inflammation.

СHARACTERISTICS OF CYCLIN D1-MEDIATED REGULATION OF CELL CYCLE OF PERIPHERAL BLOOD LIMPHOCYTES OF CHORNOBYL CLEAN-UP WORKERS AND PERSONS WITH MALIGNANT NEOPLASMS OF THE ORAL CAVITY, OROPHARYNX AND LARYNGOPHARYNX. / KhARAKTERYSTYKA TsYKLIN D1-OPOSEREDKOVANOÏ REGULIaTsIÏ KLITYNNOGO TsYKLU LIMFOTsYTIV PERYFERYChNOÏ KROVI UChASNYKIV LIKVIDATsIÏ NASLIDKIV AVARIÏ NA ChAES TA OSIB, KhVORYKh NA ZLOIaKISNI NOVOUTVORENNIa POROZhNYNY ROTA, ROTOVOÏ TA GORTANNOÏ ChASTYN GLOTKY.

OBJECTIVE: to explore proliferative potential of peripheral blood lymphocytes of Chornobyl clean-up workers and persons with malignant neoplasms of the oral cavity, oropharynx and laryngopharynx by level of expression of cyclin D1 and quantitative parameters of cell cycle. MATERIALS AND METHODS: A total of 294 men aged (58.47 ± 7.32) were surveyed, 215 of them were Chornobyl clean"up workers (1986-1987), exposed at the dose range 10.43-3623.31 mSv; 49 persons of the control group and 30persons with malignant neoplasms of the oral cavity, oropharynx and laryngopharynx at III, IVА and IVВ stages ofthe disease. The analysis of parameters of cell cycle and proliferative activity of peripheral blood (PB) lymphocyteswas performed using the flow cytometry. The evaluation of distribution of cells by G0/G1, S, G2/M cell cycle phaseswas done in vivo and in in vitro. Proliferative potential was analyzed by level of expression of cytoplasmic protein ofcyclin D1. RESULTS: Proliferative potential of PB lymphocytes of Chornobyl clean"up workers and persons with malignant neo"plasms of the oral cavity, oropharynx and laryngopharynx was assessed. An increase in the level of spontaneousсyclin D1 expression and disturbance of сyclin D1-dependent regulation of cell cycle of PB lymphocytes after mito"gen activation were determined in the Chornobyl clean-up workers. An increase in pool of cells in the S" and G2/M"phases of cell cycle was detected, which characterizes high proliferative potential of PB lymphocytes. These changesare most pronounced in the subgroup of persons with a radiation dose of D > 500 mSv, and in persons with oncolo"gical pathology. CONCLUSIONS: A positive linear dependence has been established between the radiation dose and the number of cellsin the S"phase of cell cycle in the subgroup of Chornobyl clean"up workers with a radiation dose of D > 500 mSv. The detected changes of cyclin D1-dependent regulation of cell cycle and proliferative status of lymphocytes depend on the radiation dose, can be a manifestation of genome instability and be a cause for risks of oncogenesis, in a remote period after radiation exposure.

Activation of efficient DNA repair mechanisms after photon and proton irradiation of human chondrosarcoma cells.

Although particle therapy with protons has proven to be beneficial in the treatment of chondrosarcoma compared to photon-based (X-ray) radiation therapy, the cellular and molecular mechanisms have not yet been sufficiently investigated. Cell viability and colony forming ability were analyzed after X-ray and proton irradiation (IR). Cell cycle was analyzed using flow cytometry and corresponding regulator genes and key players of the DNA repair mechanisms were measured using next generation sequencing, protein expression and immunofluorescence staining. Changes in metabolic phenotypes were determined with nuclear magnetic resonance spectroscopy. Both X-ray and proton IR resulted in reduced cell survival and a G2/M phase arrest of the cell cycle. Especially 1 h after IR, a significant dose-dependent increase of phosphorylated γH2AX foci was observed. This was accompanied with a reprogramming in cellular metabolism. Interestingly, within 24 h the majority of clearly visible DNA damages were repaired and the metabolic phenotype restored. Involved DNA repair mechanisms are, besides the homology directed repair (HDR) and the non-homologous end-joining (NHEJ), especially the mismatch mediated repair (MMR) pathway with the key players EXO1, MSH3, and PCNA. Chondrosarcoma cells regenerates the majority of DNA damages within 24 h. These molecular mechanisms represent an important basis for an improved therapy.

DNA repair inhibitors sensitize cells differently to high and low LET radiation.

The aim of this study was to investigate effects of high LET α-radiation in combination with inhibitors of DDR (DNA-PK and ATM) and to compare the effect with the radiosensitizing effect of low LET X-ray radiation. The various cell lines were irradiated with α-radiation and with X-ray. Clonogenic survival, the formation of micronuclei and cell cycle distribution were studied after combining of radiation with DDR inhibitors. The inhibitors sensitized different cancer cell lines to radiation. DNA-PKi affected survival rates in combination with α-radiation in selected cell lines. The sensitization enhancement ratios were in the range of 1.6-1.85 in cancer cells. ATMi sensitized H460 cells and significantly increased the micronucleus frequency for both radiation qualities. ATMi in combination with α-radiation reduced survival of HEK293. A significantly elicited cell cycle arrest in G2/M phase after co-treatment of ATMi with α-radiation and X-ray. The most prominent treatment effect was observed in the HEK293 by combining α-radiation and inhibitions. ATMi preferentially sensitized cancer cells and normal HEK293 cells to α-radiation. DNA-PKi and ATMi can sensitize cancer cells to X-ray, but the effectiveness was dependent on cancer cells itself. α-radiation reduced proliferation in primary fibroblast without G2/M arrest.

DNMT3A and DNMT3B Targeting as an Effective Radiosensitizing Strategy in Embryonal Rhabdomyosarcoma.

Rhabdomyosarcoma (RMS) is the most common soft tissue sarcoma in childhood. Recently, we demonstrated the overexpression of both DNA methyltransferase 3A (DNMT3A) and 3B (DNMT3B) in RMS tumour biopsies and cell lines compared to normal skeletal muscle. Radiotherapy may often fail due to the abnormal expression of some molecules able to drive resistance mechanisms. The aim of this study was to analyse the involvement of DNMT3A and DNMT3B in radioresistance in RMS. RNA interference experiments against DNMT3A/3B were performed in embryonal RMS cells, upon ionizing radiation (IR) exposure and the effects of the combined treatment on RMS cells were analysed. DNMT3A and DNMT3B knocking down increased the sensitivity of RMS cells to IR, as indicated by the drastic decrease of colony formation ability. Interestingly, DNMT3A/3B act in two different ways: DNMT3A silencing triggers the cellular senescence program by up-regulating p16 and p21, whilst DNMT3B depletion induces significant DNA damage and impairs the DNA repair machinery (ATM, DNA-PKcs and Rad51 reduction). Our findings demonstrate for the first time that DNMT3A and DNMT3B overexpression may contribute to radiotherapy failure, and their inhibition might be a promising radiosensitizing strategy, mainly in the treatment of patients with metastatic or recurrent RMS tumours.

Effects of 445 nm, 520 nm, and 638 nm Laser Irradiation on the Dermal Cells.

Background: The invention of non-ionizing emission devices revolutionized science, medicine, industry, and the military. Currently, different laser systems are commonly used, generating the potential threat of excessive radiation exposure, which can lead to adverse health effects. Skin is the organ most exposed to laser irradiation; therefore, this study aims to evaluate the effects of 445 nm, 520 nm, and 638 nm non-ionizing irradiation on keratinocytes and fibroblasts. Methods: Keratinocytes and fibroblasts were exposed to a different fluency of 445 nm, 520 nm, and 638 nm laser irradiation. In addition, viability, type of cell death, cell cycle distribution, and proliferation rates were investigated. Results: The 445 nm irradiation was cytotoxic to BJ-5ta (≥58.7 J/cm2) but not to Ker-CT cells. Exposure influenced the cell cycle distribution of Ker-CT (≥61.2 J/cm2) and BJ-5ta (≥27.6 J/cm2) cells, as well as the Bj-5ta proliferation rate (≥50.5 J/cm2). The 520 nm irradiation was cytotoxic to BJ-5ta (≥468.4 J/cm2) and Ker-CT (≥385.7 J/cm2) cells. Cell cycle distribution (≥27.6 J/cm2) of Ker-CT cells was also affected. The 638 nm irradiation was cytotoxic to BJ-5ta and Ker-CT cells (≥151.5 J/cm2). The proliferation rate and cell cycle distribution of BJ-5ta (≥192.9 J/cm2) and Ker-CT (13.8 and 41.3 J/cm2) cells were also affected. Conclusions: At high fluences, 455 nm, 520 nm, and 638 nm irradiation, representing blue, green, and red light spectra, are hazardous to keratinocytes and fibroblasts. However, laser irradiation may benefit the cells at low fluences by modulating the cell cycle and proliferation rate.

Study of the radiosensitization of docetaxel in human esophageal squamous carcinoma ECA109 cell line.

The aim of this study was to determine the radio sensitization of docetaxel in human esophageal squamous carcinoma ECA109 cell line by observing the effects of docetaxel in ECA109 cell proliferation, cell cycle distribution, apoptosis rate and related protein expression. Docetaxel inhibits the proliferation in ECA109 cell line in a dose-dependent and time-dependent manner, and 1nM was chosen for radio sensitization according to the inhibition curves. The D0 and SF2 values of ECA109 cells were 3.00Gy and 0.95, respectively, and of docetaxel (1nM) with irradiation group were 2.54Gy and 0.88. G0/G1 decreased (P<0.05), G2/M phase saw a spike (P<0.05) in the docetaxel with radiation group at 12h, 24h and 48h, while the apoptotic index witnessed a surge at 24h and 48h (P<0.05). The docetaxel with radiation group obtained a higher expression of p21 and bax protein than the docetaxel group and the radiation group (P<0.05), and a higher ratio of bcl-2/bax than the others (P<0.05). Docetaxel could inhibit the proliferation in ECA109 cell line. p21, bax, bcl-2 and other related proteins can regulate cell cycle phase distribution and induce cell apoptosis, thereby increasing the radiosensitivity effect of docetaxel in ECA109 cell line.

Destabilizing Effects of Ionizing Radiation on Chromosomes: Sizing up the Damage.

For long-term survival and evolution, all organisms have depended on a delicate balance between processes involved in maintaining stability of their genomes and opposing processes that lead toward destabilization. At the level of mammalian somatic cells in renewal tissues, events or conditions that can tip this balance toward instability have attracted special interest in connection with carcinogenesis. Mutations affecting DNA (and its subsequent repair) would, of course, be a major consideration here. These may occur spontaneously through endogenous cellular processes or as a result of exposure to mutagenic environmental agents. It is in this context that we discuss the rather unique destabilizing effects of ionizing radiation (IR) in terms of its ability to cause large-scale structural rearrangements to the genome. We present arguments supporting the conclusion that these and other important effects of IR originate largely from microscopically visible chromosome aberrations.

Fractionated Irradiation of Right Thorax Induces Abscopal Damage on Bone Marrow Cells via TNF-α and SAA.

Radiation-induced abscopal effect (RIAE) outside of radiation field is becoming more attractive. However, the underlying mechanisms are still obscure. This work investigated the deleterious effect of thoracic irradiation (Th-IR) on distant bone marrow and associated signaling factors by irradiating the right thorax of mice with fractionated doses (8 Gy × 3). It was found that this localized Th-IR increased apoptosis of bone marrow cells and micronucleus formation of bone marrow polychromatic erythrocytes after irradiation. Tandem mass tagging (TMT) analysis and ELISA assay showed that the concentrations of TNF-α and serum amyloid A (SAA) in the mice were significantly increased after Th-IR. An immunohistochemistry assay revealed a robust increase in SAA expression in the liver rather than in the lungs after Th-IR. In vitro experiments demonstrated that TNF-α induced SAA expression in mouse hepatoma Hepa1-6 cells, and these two signaling factors induced DNA damage in bone marrow mesenchymal stem cells (BMSCs) by increasing reactive oxygen species (ROS). On the other hand, injection with TNF-α inhibitor before Th-IR reduced the secretion of SAA and attenuated the abscopal damage in bone marrow. ROS scavenger NAC could also mitigated Th-IR/SAA-induced bone marrow damage in mice. Our findings indicated that Th-IR triggered TNF-α release from lung, which further promoted SAA secretion from liver in a manner of cascade reaction. Consequently, these signaling factors resulted in induction of abscopal damage on bone marrow of mice.