DNA Damage Assays Research Articles

Supramolecular PEG-DNA-Ferrocene Nanogels for Synergistically Amplified Chemodynamic Therapy via Cascade Reactions.

Chemodynamic therapy (CDT) has been limited by the tumor microenvironment, such as the low concentration of hydrogen peroxide (H2O2). The combination of therapeutic strategies that increase H2O2 with CDT can synergistically enhance the therapeutic effect. Herein, a novel supramolecular PEG-DNA-ferrocene nanogel that can codeliver glucose oxidase (GOx) and the hypoxia-activable prodrug tirapazamine (TPZ) was developed to synergistically amplify CDT via cascade reactions. The DNA nanogel was size-controllable and DNase I-responsive and exhibited good biocompatibility. Induced by oxygen consumption and H2O2 generation in the catalytic reaction of GOx, the drugs TPZ and ferrocene in the nanogel underwent the hypoxia-based reaction and the Fenton reaction, respectively. The vitro model tests, intracellular ROS test, MTT experiments, and DNA damage assay demonstrated that the H2O2-based cascade Fenton reaction and the hypoxia-based cascade reaction obviously increased ·OH generation and promoted the apoptosis of cancer cells. This cascade supramolecular nanoplatform provided a promising therapeutic strategy to synergistically amplify CDT.

SGLT1 inhibition alleviates radiation-induced intestinal damage through promoting mitochondrial homeostasis

Radiation-induced intestinal injury (RIII) constitutes a challenge in radiotherapy. Ionizing radiation (IR) induces DNA and mitochondrial damage by increasing reactive oxygen species (ROS). Sodium–glucose cotransporter 1 (SGLT1) is abundant in the gastrointestinal tract and the protective effects of inhibited SGLT1 in kidney and cardiovascular disease have been widely reported. However, the function of SGLT1 in RIII remains unclear. Herein, we reported that IR induced intestinal epithelial cell damage along with upregulation of SGLT1 in vivo and in vitro, which was alleviated by inhibition of SGLT1. Specifically, maintaining intestinal cell homeostasis was detected through cellular proliferation, apoptosis, and DNA damage assays, promoting epithelial regeneration and lifespan extension. Considering the importance of mitochondrial function in cell fate, we next confirmed that SGLT inhibition maintains mitochondrial homeostasis through enhanced mitophagy in intestinal epithelial cells. Finally, based on the bioinformatics analysis and cell validation, we demonstrated that inhibition of SGLT1 suppresses the PI3K/AKT/mTOR pathway to enhance mitophagy activation post-irradiation. In addition, we preliminarily demonstrate that SGLT inhibitors do not affect the radiosensitivity of tumors. Hence, our findings suggest that inhibition of SGLT is a promising therapeutic strategy to protect against RIII. To the best of our knowledge, this is the first report on the potential effect of SGLT1 inhibition in RIII.

Biogenic silver nanoparticles from Simarouba glauca DC leaf extract: Synthesis, characterization, and anticancer efficacy in lung cancer cells with protective effects in Caenorhabditis elegans

This study explores the synthesis, characterization, and biomedical applications of silver nanoparticles (AgNPs) synthesized using Simarouba glauca leaf extract. The biogenic AgNPs were characterized through UV–visible spectroscopy, X-ray diffraction (XRD), particle size analysis, zeta potential analysis, energy dispersive X-ray spectroscopy (EDX), Fourier-transform infrared spectroscopy (FTIR), atomic force microscopy (AFM), and high-resolution transmission electron microscopy (HR-TEM). The nanoparticles exhibited a distinct absorbance peak at 413.5 nm, confirming their synthesis and surface plasmon resonance. XRD and HR-TEM analyses revealed a face-centered cubic structure with an average size of 12.45 nm, while AFM indicated a mean particle size of 18.34 nm. The particles demonstrated moderate stability with a zeta potential of −41.4 mV and exhibited various elemental compositions as confirmed by EDX. In the biomedical evaluation, the anticancer potential of SG-AgNPs was tested on L-132 and A549 cell lines using MTT, live/dead, and DNA damage assays. Results showed dose-dependent cytotoxicity, with significant effects observed at higher concentrations, particularly against A549 cells. Additionally, the protective effects of SG-AgNPs were assessed in Caenorhabditis elegans using survival and paralysis assays. The nanoparticles significantly improved survival rates and reduced paralysis in worms infected with Pseudomonas aeruginosa PAO1 and Staphylococcus aureus. These findings highlight the potential of biogenic SG-AgNPs as effective agents with both anticancer and antimicrobial properties. Future research should focus on elucidating the mechanisms underlying these effects and optimizing their therapeutic applications.

Synthesis and characterization of 7-diethylamino-4-Chloromethyl coumarin: Spectroscopic analysis, molecular docking, and anticancer activity on large intestine carcinoma cells

Cancer, characterized by uncontrolled cell growth and metastasis, poses a significant global health burden, ranking as a leading cause of mortality worldwide. Colorectal cancer (CRC) specifically accounts for a substantial portion of cancer cases, with increasing incidence projected over the coming decades. While conventional treatments exist, they often entail adverse effects and limited efficacy, driving interest in natural remedies like coumarin derivatives due to their diverse biological activities and perceived safety profile. This study focuses on the synthesis and characterization of a novel compound, 7-diethylamino-4-chloromethyl coumarin (referred to as 7D4C), derived from coumarin. Structural elucidation employed Fourier transform infrared spectroscopy (FT-IR), proton and carbon-13 nuclear magnetic resonance spectroscopy (1H and 13C NMR), and mass spectrometry (MALDI-TOF-MS). Molecular docking studies were conducted to explore potential biological interactions. Furthermore, the anti-cancer potential of 7D4C was assessed using human epithelial adenocarcinom (LoVo) and healthy fibroblast (CCD-18Co) cell lines. Viability analysis, comet assay for DNA damage, and evaluation of cancer biomarkers including apoptosis, intracellular reactive oxygen species (iROS) levels, mitochondrial membrane potential (MMP), intracellular glutathione (GSH) concentration, and intracellular calcium (iCa2+) levels were performed. The synthesis of 7D4C was successfully completed, and its structure was confirmed. Molecular docking results indicate that 7D4C exhibits strong binding affinity to the p53 protein, highlighting its potential as a novel modulator of p53 activity. Subsequent investigations revealed that the synthesized compound induced apoptosis in cancer cells by reducing MMP and triggering DNA damage through the production of iROS. The promising anti-cancer activity of 7D4C in the LoVo cell line highlights its importance in coumarin-based therapies. Introducing 7D4C could significantly enhance future research in this area, leveraging insights from in vitro coumarin studies.

Sea conch (Rapana venosa) peptide hydrolysate regulates NF‐κB pathway and restores intestinal immune homeostasis in DSS‐induced colitis mice

AbstractInflammatory bowel disease (IBD) is a chronic inflammatory condition of the gastrointestinal tract. Sea conch peptide hydrolysate (CPH) was produced by enzymatic digestion of fresh conch meat with trypsin enzyme. To analyze the molecular composition, functional groups, and structural morphology of the hydrolysate, we employed liquid chromatography–mass spectrometry (LC–MS), Fourier‐transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM). Results confirmed that crude protein could be effectively digested by enzymes to generate peptides. In this study, we evaluated the bioactivities of CPH on dextran sulfate solution (DSS)‐induced colitis in mice. The findings demonstrated that CPH supplementation improved body weight, food and water intake, and colon length. The therapeutic efficacy and immunoregulatory effect of CPH were further determined. Our results exhibited that CPH treatment significantly ameliorated pathological symptoms by enhancing intestinal integrity, mucin production, and goblet cell count. Moreover, the immunoregulatory effect of CPH on mRNA expression levels of different pro‐ and anti‐inflammatory cytokines was determined. Results exhibited a decrease in the expression of pro‐inflammatory cytokines and an increase in anti‐inflammatory cytokines in the colon. Additionally, the CPH administration modulates the nuclear factor kappa B (NF‐κB) pathway, preventing DNA damage and cell death. Assays for apoptosis and DNA damage revealed that CPH reduced oxidative DNA damage and apoptosis. These findings highlight the immunomodulatory and treatment amelioration effect of CPH in reducing the severity of colitis.

In vitro antifungal activity analysis of Streptomyces sp. strain 196 against Candida albicans and Aspergillus flavus.

Numerous bioactive compounds have been reported to be produced by the members of the genus Streptomyces. During our previous studies, Streptomyces sp. strain 196 was tested for its antimicrobial activity, and bioactive compounds produced by this strain were characterized LC-MS and 1H NMR. To examine the antifungal potential of strain 196 is the goal of the current investigation. Present investigation is focused on exploring antifungal activity of extract of strain 196 (196EA) on membrane disruption potential against two fungi Candida albicans ATCC 90028 and Aspergillus flavus ITCC 5599. Results revealed that the MIC value is higher for A. flavus than for C. albicans which is 450µg/mL and 250µg/mL, respectively. Disc diffusion and spot assay also correspond to the values of the MIC for their respective pathogen. In growth curve analysis, lag and log phase are significantly affected by the extract of strain 196. The effects of extract from strain 196 on plasma membrane disruption of Candida albicans and Aspergillus flavus were analyzed in terms of ergosterol quantification assay, cellular leakage, proton efflux measurement (PM-ATPase), plasma membrane integrity assay (PI), and DNA damage assay (DAPI). Results shown that the extract of strain 196 has the potential to inhibit the cell membrane of the both pathogenic fungi which was further confirmed with the help of scanning electron microscopic (SEM) studies.

Combining [177Lu]Lu-DOTA-TOC PRRT with PARP inhibitors to enhance treatment efficacy in small cell lung cancer.

Small cell lung cancer (SCLC) is a highly aggressive tumor with neuroendocrine origin. Although SCLC frequently express somatostatin receptor type 2 (SSTR2), a significant clinical benefit of SSTR2-targeted radionuclide therapies of SCLC was not observed so far. We hypothesize that combination treatment with a PARP inhibitor (PARPi) could lead to radiosensitization and increase the effectiveness of SSTR2-targeted therapy in SCLC. SSTR2-ligand uptake of the SCLC cell lines H69 and H446 was evaluated in vitro using flow cytometry, and in vivo using SPECT imaging and cut-and-count biodistribution. Single-agent (Olaparib, Rucaparib, [177Lu]Lu-DOTA-TOC) and combination treatment responses were determined in vitro via cell viability, clonogenic survival and γH2AX DNA damage assays. In vivo, we treated athymic nude mice bearing H69 or H446 xenografts with Olaparib, Rucaparib, or [177Lu]Lu-DOTA-TOC alone or with combination treatment regimens to assess the impact on tumor growth and survival of the treated mice. H446 and H69 cells exhibited low SSTR2 expression, i.e. 60 to 90% lower uptake of SSTR2-ligands compared to AR42J cells. In vitro, combination treatment of [177Lu]Lu-DOTA-TOC with PARPi resulted in 2.9- to 67-fold increased potency relative to [177Lu]Lu-DOTA-TOC alone. We observed decreased clonogenic survival and higher amounts of persistent DNA damage compared to single-agent treatment for both Olaparib and Rucaparib. In vivo, tumor doubling times increased to 1.6-fold (H446) and 2.2-fold (H69) under combination treatment, and 1.0 to 1.1-fold (H446) and 1.1 to 1.7-fold (H69) in monotherapies compared to untreated animals. Concurrently, median survival was higher in the combination treatment groups in both models compared to monotherapy and untreated mice. Fractionating the PRRT dose did not lead to further improvement of therapeutic outcome. The addition of PARPi can markedly improve the potency of SSTR2-targeted PRRT in SCLC models in SSTR2 low-expressing tumors. Further evaluation in humans seems justified based on the results as novel treatment options for SCLC are urgently needed.

Phase-separated super-enhancers confer an innate radioresistance on genomic DNA.

Recently, biomolecular condensates formed through liquid-liquid phase separation have been widely reported to regulate key intracellular processes involved in cell biology and pathogenesis. BRD4 is a nuclear protein instrumental to the establishment of phase-separated super-enhancers (SEs) to direct the transcription of important genes. We previously observed that protein droplets of BRD4 became hydrophobic as their size increase, implying an ability of SEs to limit the ionization of water molecules by irradiation. Here, we aim to establish if SEs confer radiation resistance in cancer cells. We established an in vitro DNA damage assay that measures the effect of radicals provoked by the Fenton reaction on DNA integrity. This revealed that DNA damage was markedly reduced when BRD4 underwent phase separation with DNA. Accordingly, co-focal imaging analyses revealed that SE foci and DNA damage foci are mutually exclusive in irradiated cells. Lastly, we observed that the radioresistance of cancer cells was significantly reduced when irradiation was combined with ARV-771, a BRD4 de-stabilizer. Our data revealed the existence of innately radioresistant genomic regions driven by phase separation in cancer cells. The disruption of these phase-separated components enfolding genomic DNA may represent a novel strategy to augment the effects of radiotherapy.

Fischer's oligopeptide ratio in ischemic hypoxia: prophylactic amendment of sophoretin and melatonin supplementation.

Aim: The fundamental pathophysiology of ischemic-hypoxia is oxygen depletion. Fischer's ratio is essential for monitoring hypoxia intensity. Methods: the current study highlighted the prophylactic role of sophoretin (QRC) and/or melatonin (MLN) versus sodium nitrite (SN) brain hypoxia. Results: Prophylactic treatment with sophoretin and MLN, was preceded with hypoxia-induction via sodium nitrite (60mg/kg, S.C.). SN decreased hemoglobin (Hb), elevatedHIF-α, HSP-70, IL-6 and TNF-α. Sophoretin and/or MLN restored the ameliorated inflammatory biomarkers, modulatednorepinephrine, dopamine, serotonin and gamma-aminobutyricacid (GABA). Similarly, single-cell gel electrophoresis (SCGE or COMET) DNA damage assay confirmed this finding. Conclusion: Treatment via sophoretin and MLN was the most effective therapy for improving sodium nitrite-induced brain injury.

An Overview Of The Biological Methods Used To Assess DNA Damage In Humans

The purpose of this work is to summarize the biological methods available for assessing DNA damage in humans at present. There are several methods for determining single-strand DNA breaks, alkali-labile sites, and crosslinks, including comet assays, micronucleus assays, cytogenetics (which include sister chromatid exchange and chromosomal aberration assays), DNA repair assays, oxidative DNA damage assays (measuring oxidized bases such as 8-oxo-7, 8-dihydro-2'-deoxyguanosine), and oxidized bases. There are many factors to consider when determining the best method, including how to achieve the study's objectives, what type of DNA damage to measure, and what resources are available. Combining different techniques may also contribute to a more comprehensive understanding of DNA damage and its effects on human health. By standardizing assays and advancing technology, we will be able to determine DNA damage in humans more accurately.

In Vitro Wound Healing and Anticancer Effects of Ixora coccinea in Malignant Melanoma Cell Lines.

Background Ixora coccinea is a medicinal plant with many active constituents that are responsible for wound healing and have anticancer properties. Herbal extracts increase the mechanisms related to wound healing, like blood clotting, fighting infection, and epithelialization. The effect responsible for this property may be the presence of phytoconstituents like flavonoids, polyphenols, and alkaloids. Many researchers have evaluated the wound-healing effect of I. coccinea leaf extract in aqueous methanol. This study aimed to determine the in vitro wound healing and anticancer efficacy of I. coccinea leaf ethyl acetate extract and evaluate the in silico docking of the selected phytoconstituents of I. coccinea in the 2vcj protein. Materials and methods The human dermal fibroblast cell line was used to determine the rates of cell migration and proliferation for evaluating the wound-healing effect of the I. coccinea leaf ethyl acetate fraction. 4',6-diamidino-2-phenylindole (DAPI)fluorescence labeling was used to estimate the rate of cell migration. The one-step TUNEL (TdT-mediated dUTP Nick-End Labeling) in situ apoptosis kit and the annexin V-FITC/7-AAD apoptosis kit were used to perform DNA damage assays in the malignant melanoma cell line. The ethyl acetate fraction of I. coccinea leaves was analyzed for its impact on wound healing markers, including keratin-10, keratin-14, type IV collagen, and α-SMA. Results The wound-healing nature was interesting in the ethyl acetate fraction at doses of 50 µg/mL and 100 µg/mL. Both studies involved in the DNA damage study against malignant melanoma cell lines showed the cleavage of apoptotic cancer cells, which was detected using a fluorescence microscope. When compared with the control, a dose of 100 μg/ml of ethyl acetate fraction from the leaves of I. coccinea showed fibroblast migration of cells into the wound area. The statistical values were considered significant at the level of P < 0.05. An in silico docking study on the 2vcj protein revealed that selected phytoconstituents of I. coccinea resulted in good docking scores to inhibit Hsp90. Conclusion I. coccinea ethyl acetate leaf extract can inhibit the growth of malignant melanoma cell lines and promote wound healing, as shown by the study results. It might be a viable therapeutic modality for skin cancer.

Indigo dyes: Toxicity, teratogenicity, and genotoxicity studies in zebrafish embryos

Wastewater released by textile dyeing industries is a major source of pollution. Untreated wastewater released from indigo dyeing operations affects aquatic ecosystems and threatens their biodiversity. We have assessed the toxicity of natural and synthetic indigo dye in zebrafish embryos, using the endpoints of teratogenicity, genotoxicity, and histopathology. The zebrafish embryo toxicity test (ZFET) was conducted, exposing embryos to ten concentrations of natural and synthetic indigo dyes; the 96-hour LC50 values were approximately 350 and 300 mg/L, respectively. Both dyes were teratogenic, causing egg coagulation, tail detachment, yolk sac edema, pericardial edema, and tail bend, with no significant difference in effects between the natural and synthetic dyes. Both dyes were genotoxic (using comet assay for DNA damage). Real-time RT-PCR studies showed upregulation of the DNA-repair genes FEN1 and ERCC1. Severe histological changes were seen in zebrafish larvae following exposure to the dyes. Our results show that indigo dyes may be teratogenic and genotoxic to aquatic organisms, underscoring the need for development of sustainable practices and policies for mitigating the environmental impacts of textile dyeing.

Abstract 2783: The exosomes from cord blood stem cells, containing novel miRNAs, induce apoptosis in melanoma cells and enhance T cell anticancer function

Abstract Regulatory T (Treg) cells expressing FOXP3 play a critical role in suppressing immune responses against anti-tumor immune responses. However, their presence in tumor tissues is often associated with poor prognosis. Cord blood stem cell-derived exosome vesicles (CBSC-EV) constitute a valuable source of lipids, microRNAs, and proteins, that are essential for cell-to-cell communication and provide therapeutic benefits. This study aimed to investigate the contents of CBSC-EV, identifying several known miRNAs (from Let7 and Let5 families) and two unknown miRNAs. Healthy lymphocytes, fibroblasts, and CHL1 amelanotic melanoma cell lines were transfected with these two novel miRNA inhibitors, and the changes before and after treatment compared to CBSC-EV and H2O2 were examined. Following treatment, the cells underwent a 24-hour incubation period, during which the level of cytotoxicity was assessed using CCK8, and the degree of DNA damage incurred was quantified with the Fast Microplate DNA damage assay. To further investigate the effects of treatment, RNA sequencing was conducted on both healthy and cancerous cells. The results demonstrated that CBSC-EV and novel miRNAs induced cytotoxicity in cancer cells, while in healthy cells, the DNA damage was repaired and cell viability was significantly increased (p&amp;lt;0.001). RNA sequencing revealed that following treatment with CBSC-EV and both CBSC-EV+N1 and N2 inhibitors in malignant melanoma cells, the expression of genes involved in the cytokine-mediated signaling pathway, cytokine-cytokine interaction, and cytokine activity were enhanced. In healthy cells treated with CBSC-EV and novel miRNA inhibitor transfection, the MT-CO1 gene was upregulated, contributing to cytochrome-c oxidase activity. This study presents evidence of the potential use of novel miRNAs as genetic material for cancer therapeutics in the future. Additionally, the findings suggest that these miRNAs could be used as an immune system modulator against melanoma. These findings demonstrate that miRNAs can effectively suppress resistance to anticancer cytotoxic therapy, which is a common feature of cancer cells. This suggests that miRNAs can potentially enhance current cancer therapies. Citation Format: Mojgan Mojgan Najafzadeh, Adi Baumgartner, Shohreh Jafarinejad, Zahra Karimi, Mohammad Isreb, Pouria Akhbari, Nader Ghaderi, Farshid Sefat, Saeed Heidari Keshel, Parisa Naeem, Rojan Ghaderi, Jacobo Elis Gomez, Diana Anderson, Andrew Wright. The exosomes from cord blood stem cells, containing novel miRNAs, induce apoptosis in melanoma cells and enhance T cell anticancer function [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 2783.

Use of CRISPR/Cas9 with Homology-Directed Repair to Gene-Edit Topoisomerase IIβ in Human Leukemia K562 Cells: Generation of a Resistance Phenotype.

DNA topoisomerase IIβ (TOP2β/180; 180 kDa) is a nuclear enzyme that regulates DNA topology by generation of short-lived DNA double-strand breaks, primarily during transcription. TOP2β/180 can be a target for DNA damage-stabilizing anticancer drugs, whose efficacy is often limited by chemoresistance. Our laboratory previously demonstrated reduced levels of TOP2β/180 (and the paralog TOP2α/170) in an acquired etoposide-resistant human leukemia (K562) clonal cell line, K/VP.5, in part due to overexpression of microRNA-9-3p/5p impacting post-transcriptional events. To evaluate the effect on drug sensitivity upon reduction/elimination of TOP2β/180, a premature stop codon was generated at the TOP2β/180 gene exon 19/intron 19 boundary (AGAA//GTAA→ATAG//GTAA) in parental K562 cells (which contain four TOP2β/180 alleles) by CRISPR/Cas9 editing with homology-directed repair to disrupt production of full-length TOP2β/180. Gene-edited clones were identified and verified by quantitative polymerase chain reaction and Sanger sequencing, respectively. Characterization of TOP2β/180 gene-edited clones, with one or all four TOP2β/180 alleles mutated, revealed partial or complete loss of TOP2β mRNA/protein, respectively. The loss of TOP2β/180 protein correlated with decreased (2-{4-[(7-chloro-2-quinoxalinyl)oxy]phenoxy}propionic acid)-induced DNA damage and partial resistance in growth inhibition assays. Partial resistance to mitoxantrone was also noted in the gene-edited clone with all four TOP2β/180 alleles modified. No cross-resistance to etoposide or mAMSA was noted in the gene-edited clones. Results demonstrated the role of TOP2β/180 in drug sensitivity/resistance in K562 cells and revealed differential paralog activity of TOP2-targeted agents. SIGNIFICANCE STATEMENT: Data indicated that CRISPR/Cas9 editing of the exon 19/intron 19 boundary in the TOP2β/180 gene to introduce a premature stop codon resulted in partial to complete disruption of TOP2β/180 expression in human leukemia (K562) cells depending on the number of edited alleles. Edited clones were partially resistant to mitoxantrone and XK469, while lacking resistance to etoposide and mAMSA. Results demonstrated the import of TOP2β/180 in drug sensitivity/resistance in K562 cells and revealed differential paralog activity of TOP2-targeted agents.

LC3B drives transcription-associated homologous recombination via direct interaction with R-loops.

Exploring the connection between ubiquitin-like modifiers (ULMs) and the DNA damage response (DDR), we employed several advanced DNA damage and repair assay techniques and identified a crucial role for LC3B. Notably, its RNA recognition motif (RRM) plays a pivotal role in the context of transcription-associated homologous recombination (HR) repair (TA-HRR), a particular subset of HRR pathways. Surprisingly, independent of autophagy flux, LC3B interacts directly with R-loops at DNA lesions within transcriptionally active sites via its RRM, promoting TA-HRR. Using native RNA immunoprecipitation (nRIP) coupled with high-throughput sequencing (nRIP-seq), we discovered that LC3B also directly interacts with the 3'UTR AU-rich elements (AREs) of BRCA1 via its RRM, influencing its stability. This suggests that LC3B regulates TA-HRR both proximal to and distal from DNA lesions. Data from our LC3B depletion experiments showed that LC3B knockdown disrupts end-resection for TA-HRR, redirecting it towards the non-homologous end joining (NHEJ) pathway and leading to chromosomal instability, as evidenced by alterations in sister chromatid exchange (SCE) and interchromosomal fusion (ICF). Thus, our findings unveil autophagy-independent functions of LC3B in DNA damage and repair pathways, highlighting its importance. This could reshape our understanding of TA-HRR and the interaction between autophagy and DDR.

Zeocin-induced DNA damage response in barley and its dependence on ATR

DNA damage response (DDR) is an essential mechanism by which living organisms maintain their genomic stability. In plants, DDR is important also for normal growth and yield. Here, we explored the DDR of a temperate model crop barley (Hordeum vulgare) at the phenotypic, physiological, and transcriptomic levels. By a series of in vitro DNA damage assays using the DNA strand break (DNA-SB) inducing agent zeocin, we showed reduced root growth and expansion of the differentiated zone to the root tip. Genome-wide transcriptional profiling of barley wild-type and plants mutated in DDR signaling kinase ATAXIA TELANGIECTASIA MUTATED AND RAD3-RELATED (hvatr.g) revealed zeocin-dependent, ATR-dependent, and zeocin-dependent/ATR-independent transcriptional responses. Transcriptional changes were scored also using the newly developed catalog of 421 barley DDR genes with the phylogenetically-resolved relationships of barley SUPRESSOR OF GAMMA 1 (SOG1) and SOG1-LIKE (SGL) genes. Zeocin caused up-regulation of specific DDR factors and down-regulation of cell cycle and histone genes, mostly in an ATR-independent manner. The ATR dependency was obvious for some factors associated with DDR during DNA replication and for many genes without an obvious connection to DDR. This provided molecular insight into the response to DNA-SB induction in the large and complex barley genome.

P161 The use of Novel Natural Treatments for Inflammatory Bowel Diseases

Abstract Background Background: Free radicals and reduced antioxidant levels lead to oxidative stress, which plays a role in causing Inflammatory Bowel Disease (IBD). IBD is a chronic gastrointestinal autoimmune condition that involves an abnormal immune response. This includes Crohn's disease (CD) and ulcerative colitis (UC). In the previous studies, we demonstrated the antioxidant effect of Inonotus obliquus (IO) and flavonoids such as quercetin and epicatechin on lymphocytes from IBD patients. In vitro studies have shown that Chaga extract is effective in reducing oxidative stress in lymphocytes of both healthy individuals and those with IBD. This suggests that Chaga extract may be a useful supplement for anyone looking to inhibit oxidative stress. Methods Methods: In our current study, Cord Blood Stem Cells -derived Exosomes (CBSC Exo) and their synthesised miRNAs were investigated as antioxidant/anti-inflammatory elements on lymphocytes and 3D intestinal epithelial model. There were seven miRNAs found in CBSCs Exo, and among them were two miRNAs that were identified as novel. The Peripheral Blood Monocyte Cells (PBMCs) from IBD patients and healthy individuals after challenging with H2O2 or Interleukin 6 were treated with CBSCs Exo, transfected with miRNA novels or both. The treatment method also was applied to the EpiltestinalTK 3D model from Mattek. Various techniques were utilised, including the Comet assay, Fast Microplate DNA damage assay, and CCK8. Results The findings of the study indicate that the administration of CBSC-derived Exo, Let-7c-mimic miRNA, Let7bSb miRNA, as well as Novel 1 and Novel 2 miRNAs on the 3D model intestine, significantly decreased the level of DNA damage when compared to the positive control H2O2 and IL6, as well as the untreated samples. Conclusion Conclusions: In conclusion, certain natural substances like flavonoids, Inonotus obliquus, and exosomes derived from CBSCs may have an advantage in decreasing significantly oxidative stress and DNA damage in IBD Peripheral Blood Mononuclear Cells (PBMCs) and inflamed intestinal 3D models.

P064 Investigating the genotoxic effect of reduced glutathione, n-acetylcysteine, human umbilical cord-derived mesenchymal stem cell exosomes and let-7 miRNA mimics in human lymphocytes and EpiIntestinal cells

Abstract Background The current treatments for IBD frequently do not provide sufficient control over the disease, warranting the investigation of alternative therapeutic options with minimal risk of side effects. In IBD, the overgeneration and insufficient removal of reactive oxygen species (ROS) leads to oxidative stress. Reduced glutathione (GSH) and n-acetylcysteine (NAC) are antioxidants which may possess therapeutic potential in IBD, by modulating endogenous mechanisms that decrease ROS production or increase antioxidant enzymes. Additonally, exosomes from human umbilical cord blood derived mesenchymal stem cells (hucMSCs-exo) may be used to treat IBD. These are a subset of extracellular nanosized membrane vesicles which participate in intercellular communication by delivering their contents, such as functional miRNAs to recipient cells, thereby influencing the physiological and pathological processes in various diseases. The therapeutic potential of exosomes can be enhanced through the overexpression of the let-7 family of miRNAs. Methods The EpiIntestinal tissue model is a physiologically relevant predictor of drug-induced GI toxicity. EpiIntestinal cells and lymphocytes from 3 IBD patients were transfected with 50 μL miRNA mimics and inhibitors, and treated with 50μL hucMSC-exo, and 50 μL 1mM GSH and NAC. Next, in comparison to negative controls, single-stranded DNA damage was assessed in peripheral blood mononuclear cells (PBMCs) from IBD patients using the fast microplate DNA damage assay, and double-stranded DNA damage was assessed in EpiIntestinal cells using the alkaline Comet assay. In addition, the viability of healthy and IBD lymphocytes was assessed following treatment with selected concentrations of hucMSC-exo, GSH and NAC. Results Double-stranded DNA damage was significantly reduced in EpiIntestinal cells compared to the negative control following treatment with hucMSC-exo, GSH, NAC, and miRNA mimics for let-7a-5p, -7b-5p, -7c-3p, -7d-3p and -7d-5p. In addition, single-stranded DNA damage was reduced in IBD PBMCs compared to the negative control following treatment with hucMSC-exo, and let-7b-5p and -7c-3p mimics, but was increased following treatment with inhibitors for let-7b-5p, -7c-5p and two novel miRNAs. Additionally, GSH, NAC and hucMSC-exo increased cell viability in treated versus untreated lymphocytes from healthy individuals and IBD patients. Conclusion Selected concentrations of HucMSC-exo, GSH, NAC and/or let-7 miRNA mimics reduced DNA damage and increased cell viability in treated versus untreated cells which may reduce the risk of colorectal cancer in IBD patients. Acknowledgements Our gratitude goes to the MatTek Team for generously granting us a SMI-100-FT EpiIntestinal kit in support of this research.

Lung Cancer in Ever- and Never-Smokers: Findings from Multi-Population GWAS Studies.

Clinical, molecular, and genetic epidemiology studies displayed remarkable differences between ever- and never-smoking lung cancer. We conducted a stratified multi-population (European, East Asian, and African descent) association study on 44,823 ever-smokers and 20,074 never-smokers to identify novel variants that were missed in the non-stratified analysis. Functional analysis including expression quantitative trait loci (eQTL) colocalization and DNA damage assays, and annotation studies were conducted to evaluate the functional roles of the variants. We further evaluated the impact of smoking quantity on lung cancer risk for the variants associated with ever-smoking lung cancer. Five novel independent loci, GABRA4, intergenic region 12q24.33, LRRC4C, LINC01088, and LCNL1 were identified with the association at two or three populations (P < 5 × 10-8). Further functional analysis provided multiple lines of evidence suggesting the variants affect lung cancer risk through excessive DNA damage (GABRA4) or cis-regulation of gene expression (LCNL1). The risk of variants from 12 independent regions, including the well-known CHRNA5, associated with ever-smoking lung cancer was evaluated for never-smokers, light-smokers (packyear ≤ 20), and moderate-to-heavy-smokers (packyear > 20). Different risk patterns were observed for the variants among the different groups by smoking behavior. We identified novel variants associated with lung cancer in only ever- or never-smoking groups that were missed by prior main-effect association studies. Our study highlights the genetic heterogeneity between ever- and never-smoking lung cancer and provides etiologic insights into the complicated genetic architecture of this deadly cancer.

Amelioration of gold nanoparticles mediated through Ocimum oil extracts induces reactive oxygen species and mitochondrial instability against MCF-7 breast carcinoma.

Phytomedicines are potential immunity-boosting components with effective anticystic properties, minimal side effects, and biomedical applications, making them valuable for combating various diseases. India is renowned globally for Ayurveda, an ancient treatment methodology known for its holistic approach in identifying the root cause of diseases. Tulsi (Ocimum sanctum) is a common household medicine in India. While essential oils from plants like Tulsi have long been recognized for their medicinal properties, there is a gap in understanding their potential in synthesizing gold nanoparticles (AuNPs) and their efficacy against breast carcinoma, particularly in the context of immunosuppressive conditions. We investigated the potential application of essential oils isolated from O. sanctum in the synthesis of AuNPs and their efficacy against MCF-7 breast carcinoma. Gas chromatography-mass spectroscopy identified compounds with potential anticancer effects against breast cancer cells. Synthesised AuNPs displayed high hemocompatibility and antimicrobial activity against nosocomial Pseudomonas aeruginosa, Escherichia coli, Vibrio cholerae, and Bacillus subtilis strains. Os-AuNPs induced chromosomal instability and mitotic arrest in the G2/M cell cycle phase. Subsequent fluorescence and cell cytometry studies demonstrated the systemic release of ROS, depolarisation of mitochondrial membrane potential, and production of apoptotic bodies. DNA damage and comet assays confirmed the anticancer potential of synthesised AuNPs. This study illuminates the potential of O. sanctum-derived AuNPs in breast carcinoma treatment, paving the way for future AuNP-based therapies in biomedicine.