搜索结果：Genes and environment : the official journal of the Japanese Environmental Mutagen Society

The 48th Annual Meeting and International Conference of the Environmental Mutagen Society of India (EMSI) on 'Environmental Mutagenesis & Epigenomics in Relation to Human Health' was held at Jamshedpur Co-Operative College, in association with Kolhan University, Jharkhand, India, from January 29-31, 2026. There were 141 deliberations in total, with participation from researchers, academicians, Vice-Chancellors, and state government officials from India and eight other countries. The scientific topics, including environmental impact on humans and aquaculture, transgenerational plant protection, molecular insights into cancer research, plants with antimutagenic potential, and sustainable agriculture through the use of bio-pesticides and bio-fertilizers, broadly justified the conference theme. The molecular mechanisms of pathogenesis were discussed through lectures on signalling pathways, gene expression, and DNA damage and repair, highlighting targeted drug development. Additionally, in silico docking of synthetic drugs and nanoparticles was discussed in detail. Notably, nanotoxicology, microplastics, airborne particulate matter, and prenatal arsenic exposure were shown to have a significant impact on human health. As Jharkhand and neighbouring states depend largely on agricultural yield, discussions on the use of plant-based medicines, harnessing infection and immunity, and agricultural eco-toxicology suggested ways to protect farmers' health and the food chain from the overuse of chemicals. Altogether, the deliberations supported several Sustainable Development Goals and highlighted cost-effective agricultural modalities. These messages were disseminated to the public through local media via daily briefings. Notably, this EMSI conference provided a platform for scientific exchange that attracted administrators and pollution control regulators aimed at protecting human health by mitigating environmental exposure.

Although the in silico predictive ability of the Ames test results has recently made remarkable progress, there are still some chemical classes for which the predictive ability is not yet sufficient due to a lack of Ames test data. These classes include simple heterocyclic compounds. This study aimed to investigate the mutagenicity and structure-mutagenicity relationships for some heterocycles in the Ames test. In the present study, we selected 12 quinoline analogues containing one or two nitrogen atoms in the naphthalene ring and 12 indole analogues containing one to three nitrogen atoms in the indole ring, without any side moiety. The Ames test was performed with five standard bacterial strains (TA100, TA1535, TA98, TA1537, and WP2uvrA) using the pre-incubation method with and without rat liver S9. Five quinoline and two indole analogues were mutagenic. Among the five quinoline analogues, four were mutagenic in the presence of S9 mix with TA100, whereas cinnoline was mutagenic in the absence of S9 mix with TA1537. Among the two indole analogues, indazole was mutagenic in the presence and absence of S9 mix with WP2uvrA and 4-azaindole was mutagenic in the absence of S9 mix with TA1537. The mechanisms underlying the induction of mutagenesis appear to differ between quinoline and indole analogues. In addition, we performed in silico analysis of the mutagenicity of all these analogues using DEREK Nexus 6.1.1 (Lhasa Limited) and GT_EXPERT from CASE Ultra 1.8.0.5 (MultiCASE Inc.) as knowledge-based models and GT1_BMUT from CASE Ultra 1.8.0.5 (MultiCASE Inc.) as a statistical-based model. The knowledge-based model showed low sensitivity for both the quinoline and indole analogues (DEREK Nexus and GT_EXPERT: 20% for quinolines and 0% for indoles). Conversely, the statistical model showed high sensitivity (100% for both quinolines and indoles) and low specificity (43% for quinolines and 10% for indoles). Based on the Ames test results, we proposed structural alerts noting that quinoline analogues were mutagenic when they had nitrogens in any of the positions 2, 5, 7, or 8 in addition to 1, and indole analogues were mutagenic when they had nitrogens at positions 2 or 4 in addition to 1.

Exposure to chemical mixtures inherent in air pollution, has been shown to be associated with the risk of breast and lung cancers. However, studies on the molecular mechanisms of exposure to a mixture of these pollutants, such as hydrocarbons, in the development of breast and lung cancers are scarce. We utilized in silico toxicogenomic analysis to elucidate the molecular pathways linked to both cancers that are influenced by exposure to a mixture of selected hydrocarbons. The Comparative Toxicogenomics Database and Cytoscape software were used for data mining and visualization. Twenty-five hydrocarbons, common in air pollution with carcinogenicity classification of 1 A/B or 2 (known/presumed or suspected human carcinogen), were divided into three groups: alkanes and alkenes, halogenated hydrocarbons, and polyaromatic hydrocarbons. The in silico data-mining revealed 87 and 44 genes commonly interacted with most of the investigated hydrocarbons are linked to breast and lung cancer, respectively. The dominant interactions among the common genes are co-expression, physical interaction, genetic interaction, co-localization, and interaction in shared protein domains. Among these genes, only 16 are common in the development of both cancers. Benzo(a)pyrene and tetrachlorodibenzodioxin interacted with all 16 genes. The molecular pathways potentially affected by the investigated hydrocarbons include aryl hydrocarbon receptor, chemical carcinogenesis, ferroptosis, fluid shear stress and atherosclerosis, interleukin 17 signaling pathway, lipid and atherosclerosis, NRF2 pathway, and oxidative stress response. Within the inherent limitations of in silico toxicogenomics tools, we elucidated the molecular pathways associated with breast and lung cancer development potentially affected by hydrocarbons mixture. Our findings indicate adaptive responses to oxidative stress and inflammatory damages are instrumental in the development of both cancers. Additionally, ferroptosis-a non-apoptotic programmed cell death driven by lipid peroxidation and iron homeostasis-was identified as a new player in these responses. Finally, AHR potential involvement in modulating IL-8, a critical gene that mediates breast cancer invasion and metastasis to the lungs, was also highlighted. A deeper understanding of the interplay between genes associated with these pathways, and other survival signaling pathways identified in this study, will provide invaluable knowledge in assessing the risk of inhalation exposure to hydrocarbons mixture. The findings offer insights into future in vivo and in vitro laboratory investigations that focus on inhalation exposure to the hydrocarbons mixture.

We previously determined the antimutagenic activity of the juice of Actinidia arguta (hereafter referred to as sarunashi-juice) using the Ames test. The anticarcinogenic effect of sarunashi-juice was observed in lung and skin tumorigenesis in mice. We hypothesized that tea prepared from the leaves and twigs of A. arguta (hereafter referred to as sarunashi-tea) might also have antimutagenic and anticarcinogenic properties. We investigated the antimutagenic activity of sarunashi-tea using the Ames test, and its preventive effects on the formation of aberrant crypt foci (ACF) induced by 1,2-dimethylhydrazine (DMH) in mice. Antimutagenic results against aflatoxin B1, benzo(a)pyrene (B(a)P), 2-amino-3,8-dimethylimidazo[4,5-f]quinoxaline (MeIQx), 3-amino-1-methyl-5H-pyrido[4,3-b]indole (Trp-P-2) and 1-methyl-6-phenyl-1H-imidazo[4,5-b]pyridin-2-amine (PhIP) were observed with the administration of sarunashi-tea. The amounts of sarunashi-tea needed for 50% inhibition (ID50) toward B(a)P, MeIQx, and Trp-P-2 were 2.9, 2.5, and 6.3 times higher, respectively, than that of sarunashi-juice. The antimutagenic components present in the juice and tea prepared from sarunashi may be similar chemicals. However, the concentration of the antimutagenic substances may be 2.5–6.3 times lower in sarunashi-tea than in sarunashi-juice. The total number of ACF was significantly reduced in mice treated with DMH in the presence of sarunashi-tea compared to that in mice treated with DMH in the absence of sarunashi-tea. Further investigation of the mechanisms of antimutagenicity and anti-ACF formation and identification of active components in sarunashi-tea will be worthwhile.

When assessing the genotoxicity of substances containing probiotic candidates, such as lactic acid-producing bacteria, using the in vitro micronucleus test (MNT), bacterial growth in the test medium may reduce the pH of the medium. The low medium pH is known to induce cytotoxicity and false-positive results. In the TK6 cell system, it is difficult to completely remove the bacteria from the medium by washing post-treatment, leading to bacterial growth during the recovery period in the short-term treatment. In the present study, the low pH range yielding false positives in the TK6 cell MNT was investigated using media supplemented with acetic, lactic, or formic acids, which are non-genotoxic bacterial metabolites. Additionally, to suppress the bacterial growth during the recovery period using antibiotics, i.e., penicillin/streptomycin (P/S), gentamicin sulfate (GM), and amphotericin B (AP), the maximum applicable concentrations of them that did not affect TK6 cell growth or micronucleus induction were determined. Then, we conducted an MNT using a substance containing live lactic acid-producing bacteria to verify the effectiveness of the antibiotics. Acetic, lactic, and formic acids induced micronuclei in TK6 cells (false positive) at an initial pH of ≤ 6.2 and ≤ 6.0 in 3 h treatment with and without S9 mix, respectively, and of ≤ 6.7 in the continuous treatment. Media supplemented with P/S, GM, and AP did not affect TK6 cell growth or micronucleated cell frequencies in the negative and positive controls ≤ 400 unit/mL-400 µg/mL, ≤ 250, and ≤ 20 µg/mL, respectively. In an MNT with fermented milk containing live lactic acid-producing bacteria, supplementation with P/S or GM to media for the recovery cultures suppressed the bacterial growth, decreasing pH, and cytotoxicity. This study revealed the low pH ranges yielding false positives in the TK6 cell MNT under short-term and continuous treatment conditions. These values will serve as references for interpreting the biological relevance of results. Under short-term treatment, optimal antibiotic supplementation in recovery cultures suppressed bacterial growth in the test substance and prevented the decrease in pH that could yield false positives. This approach might be useful for evaluating the genotoxicity of test substances containing probiotic candidates using the MNT.

Both mutation induction and clonal expansion of mutated cells cause cancer. The probability of cancer development depends on mutations, clonal growth rates, and carcinogenic mechanisms. A recent study showed cases of occupational cholangiocarcinomas that originate multifocally, with higher mutation burden levels than those in common cholangiocarcinomas. This study aimed to identify the effect of clonal expansion on and estimate the risk of occupational and common intrahepatic cholangiocarcinomas (ICCs) using a multistage model modified to include the effect of cell expansion at any carcinogenic stage. The age-specific incidence of common ICC estimated from the Vital Statistics in Japan and the prognosis of ICC, and mutation frequencies of occupational and common ICC available from the previous report, were applied to a multistage model modified with cell proliferation effects. From the fittest model, the risk after exposure was estimated. The required number of stages for carcinogenesis was estimated to be three based on the incidences and mutation frequencies of occupational and common ICCs. Based on this estimation, the predicted incidence curve under the model was similar to that estimated from the ICC mortality rate, except for older adults. The model indicated a minor effect of clonal expansion on the observed occupational ICC risk. It predicted a rapid decrease in ICC risk after the cessation of occupational exposure, although the time of clinical detection of cancer after the exposure was affected by latency. The model predicted an increase in cancer risk in older adults caused by cell expansion and common background mutations. However, the risk in older adults was overestimated in the case of common ICC; this divergence could influence occupational ICC cases. Three-stage ICC carcinogenesis has been proposed. The high mutation burden levels caused by occupational exposure led to an immediate incidence of cancer. After a long period of relatively low cancer risk, an increased risk in older adults was also predicted.

Prediction of cytochrome P450 (CYP)-mediated metabolism is crucial for assessing the safety of chemicals. An in silico system to reproduce CYP1B1-mediated reactions has been developed by the reverse construction of ligand-accessible spaces from ligand assemblies as a fused grid Template* system. There are close similarities between Templates of CYP1B1 and previously established CYP1A1 (Genes & Environ 2023) in the distribution area, Site of oxidation, and the available Width, except for the use of Position 52’ (Pier-sitting) and the lack of use of the bottom in the middle region (Rings F and Ea) on CYP1B1-Template. Experiments using various substrates of both enzymes further suggested the distinct localization of Bay-2 residues on Templates of CYP1A1 and CYP1B1. More than 260 reactions of CYP1A1/1B1 ligands were examined on the present CYP1A1- and CYP1B1-Template systems. From their placements on the Templates and rules for interaction modes, verifications of good and poor substrates, regio/stereo-selectivity, and inhibition became faithfully available for these ligands. To understand the structural basis of the inhibitory interaction, various inhibitors were applied to the Templates and verified modes of the steric interactions. Both the hangings at Position 32 of CYP1A1 ligands and the adherence at Positions 24–52 of CYP1B1 ligands are suggested to retard the dissociation of Bay-2 residues from ligand molecules. Dissociation interference of ligands with Bay-2 residue is thus possible to be a mechanism of ligand-mediated inhibition on CYP1A1 and CYP1B1.

Error-corrected next-generation sequencing (ecNGS) technologies have enabled the direct evaluation of genome-wide mutations after exposure to mutagens. Previously, we reported an ecNGS methodology, Hawk-Seq™, and demonstrated its utility in evaluating mutagenicity. The evaluation of technical transferability is essential to further evaluate the reliability of ecNGS-based assays. However, cutting-edge sequencing platforms are continually evolving, which can affect the sensitivity of ecNGS. Therefore, the effect of differences in sequencing instruments on mutation data quality should be evaluated. We assessed the performance of four sequencing platforms (HiSeq2500, NovaSeq6000, NextSeq2000, and DNBSEQ-G400) with the Hawk-Seq™ protocol for mutagenicity evaluation using DNA samples from mouse bone marrow exposed to benzo[a]pyrene (BP). The overall mutation (OM) frequencies per 106 bp in vehicle-treated samples were 0.22, 0.36, 0.46, and 0.26 for HiSeq2500, NovaSeq6000, NextSeq2000, and DNBSEQ-G400, respectively. The OM frequency of NextSeq2000 was significantly higher than that of HiSeq2500, suggesting the difference to be based on the platform. The relatively higher value in NextSeq2000 was a consequence of the G:C to C:G mutations in NextSeq2000 data (0.67 per 106 G:C bp), which was higher than the mean of the four platforms by a ca. of 0.25 per 106 G:C bp. A clear dose-dependent increase in G:C to T:A mutation frequencies was observed in all four sequencing platforms after BP exposure. The cosine similarity values of the 96-dimensional trinucleotide mutation patterns between HiSeq and the three other platforms were 0.93, 0.95, and 0.92 for NovaSeq, NextSeq, and DNBSeq, respectively. These results suggest that all platforms can provide equivalent data that reflect the characteristics of the mutagens. All platforms sensitively detected mutagen-induced mutations using the Hawk-Seq™ analysis. The substitution types and frequencies of the background errors differed depending on the platform. The effects of sequencing platforms on mutagenicity evaluation should be assessed before experimentation.

Previously, Japanese Environmental Mutagen and Genome Society/Mammalian Mutagenicity Study Group/Toxicogenomics Study Group (JEMS/MMS toxicogenomic study group) proposed 12 genotoxic marker genes (Aen, Bax, Btg2, Ccnf, Ccng1, Cdkn1a, Gdf15, Lrp1, Mbd1, Phlda3, Plk2, and Tubb4b) to discriminate genotoxic hepatocarcinogens (GTHCs) from non-genotoxic hepatocarcinogens (NGTHCs) and non-genotoxic non-hepatocarcinogens (NGTNHCs) in mouse and rat liver using qPCR and RNA-Seq and confirmed in public rat toxicogenomics data, Open TG-GATEs, by principal component analysis (PCA). On the other hand, the U.S. Environmental Protection Agency (US EPA) suggested seven genotoxic marker genes (Bax, Btg2, Ccng1, Cgrrf1, Cdkn1a, Mgmt, and Tmem47) with Open TG-GATEs data. Four genes (Bax, Btg2, Ccng1, and Cdkn1a) were common in these two studies. In the present study, we examined the performance of these four genes in Open TG-GATEs data using PCA. The study's findings are of paramount significance, as these four genes proved to be highly effective in distinguishing five typical GTHCs (2-acetylaminofluorene, aflatoxin B1, 2-nitrofluorene, N-nitrosodiethylamine and N-nitrosomorpholine) from seven typical NGTHCs (clofibrate, ethanol, fenofibrate, gemfibrozil, hexachlorobenzene, phenobarbital, and WY-14643) and 11 NGTNHCs (allyl alcohol, aspirin, caffeine, chlorpheniramine, chlorpropamide, dexamethasone, diazepam, indomethacin, phenylbutazone, theophylline, and tolbutamide) by PCA at 24 h after a single administration with 100% accuracy. These four genes also effectively distinguished two typical GTHCs (2-acetylaminofluorene and N-nitrosodiethylamine) from seven NGTHCs and ten NGTNHCs by PCA on 29 days after 28 days-repeated administrations, with a similar or even better performance compared to the previous 12 genes. Furthermore, the study's analysis revealed that the three intermediate GTHC/NGTHCs (methapyrilene, monocrotaline, and thioacetamide, which were negative in the Salmonella test but positive in the in vivo rat liver test) were located in the intermediate region between typical GTHCs and typical NGTHCs by PCA. The present results unequivocally demonstrate the availability of four genotoxic marker genes ((Bax, Btg2, Ccng1, and Cdkn1a) and PCA in discriminating GTHCs from NGTHCs and NGTNHCs in Open TG-GATEs. These findings strongly support our recommendation that future rat liver in vivo toxicogenomics tests prioritize these four genotoxic marker genes, as they have proven to be highly effective in discriminating between different types of hepatocarcinogens.

The symposium "The New Era Shaped by Environmental Genome Monitoring," held in December 2024 by the Japanese Environmental Mutagen and Genome Society (JEMS), aimed to explore the interdisciplinary collaborations that are essential for the development of new scopes in environmental genome monitoring. This event highlighted the necessity of integrating mutagenicity research with ecological assessments to enhance public health and biodiversity conservation. Presentations focused on the evolving landscape of environmental genomics, including metagenomic analyses for antibiotic resistance, viral genomic surveillance in wastewater, and innovations in noninvasive biodiversity and stress monitoring through environmental DNA and RNA. This report summarizes the key discussions and presentations from the symposium, underscoring the critical role of environmental genome monitoring in shaping future safety research.

The open symposium of the Japanese Environmental Mutagen and Genome Society (JEMS) entitled "The Science Behind Safety in Our Daily Lives," was held as a hybrid in-person and online meeting on June 14, 2025. The rapid advancement of science and technology continues to profoundly alter our lifestyles. We face potential risks from chemical, biological, and physical agents, including chemical substances, bacteria/viruses, and radioactive substances, particularly in pharmaceuticals, food, and indoor environments. Furthermore, natural disasters such as earthquakes and heavy rains not only cause physical damage, but can also lead to health hazards from chemical substances and radiation. This underscores the urgent need for robust systems that can effectively respond to health crises. This symposium aimed to improve public understanding of safety science in daily life, including in pharmaceuticals, food, and living environments. In this symposium, we invited five scientists who are expanding the frontiers of health sciences. We organized this public event to be open to everyone, not just members of the JEMS. Herein, the organizers present a summary of the symposium.

Primary aromatic amines (PAAs) present significant challenges in the prediction of mutagenicity using current standard quantitative structure activity relationship (QSAR) systems, which are knowledge-based and statistics-based, because of their low positive prediction values (PPVs). Previous studies have suggested that PAAs are metabolized into genotoxic nitrenium ions. Moreover, ddE, a relative-energy based index derived from quantum chemistry calculations that measures the stability nitrenium ions, has been correlated with mutagenicity. This study aims to further examine the ability of the ddE-based approach in improving QSAR mutagenicity predictions for PAAs and to develop a refined method to decrease false positive predictions. Information on 1,177 PAAs was collected, of which 420 were from public databases and 757 were from in-house databases across 16 laboratories. The total dataset included 465 Ames test-positive and 712 test-negative chemicals. For internal PAAs, detailed Ames test data were scrutinized and final decisions were made using common evaluation criteria. In this study, ddE calculations were performed using a convenient and consistent protocol. An optimal ddE cutoff value of -5 kcal/mol, combined with a molecular weight ≤ 500 and ortho substitution groups yielded well-balanced prediction scores: sensitivity of 72.0%, specificity of 75.9%, PPV of 65.6%, negative predictive value of 80.9% and a balanced accuracy of 74.0%. The PPV of the ddE-based approach was greatly reduced by the presence of two ortho substituent groups of ethyl or larger, as because almost all of them were negative in the Ames test regardless of their ddE values, probably due to steric hindrance affecting interactions between the PAA and metabolic enzymes. The great majority of the PAAs whose molecular weights were greater than 500 were also negative in Ames test, despite ddE predictions indicating positive mutagenicity. This study proposes a refined approach to enhance the accuracy of QSAR mutagenicity predictions for PAAs by minimizing false positives. This integrative approach incorporating molecular weight, ortho substitution patterns, and ddE values, substantially can provide a more reliable basis for evaluating the genotoxic potential of PAAs.

Error-corrected next-generation sequencing (ecNGS) enables the sensitive detection of chemically induced mutations. Matsumura et al. reported Hawk-Seq™, an ecNGS method, demonstrating its utility in clarifying mutagenicity both qualitatively and quantitatively. To further promote the adoption of ecNGS-based assays, it is important to evaluate their inter-laboratory transferability and reproducibility. Therefore, we evaluated the inter-laboratory reproducibility of Hawk-Seq™ and its concordance with the transgenic rodent mutation (TGR) assay. The Hawk-Seq™ protocol was successfully transferred from the developer's laboratory (lab A) to two additional laboratories (labs B, C). Whole genomic mutations were analyzed independently using the same genomic DNA samples from the livers of gpt delta mice exposed to benzo[a]pyrene (BP), N-ethyl-N-nitrosourea (ENU), and N-methyl-N-nitrosourea (MNU). In all laboratories, clear dose-dependent increases in base substitution (BS) frequencies were observed, specific to each mutagen (e.g. G:C to T:A for BP). Statistically significant increases in overall mutation frequencies (OMFs) were identified at the same doses across all laboratories, suggesting high reproducibility in mutagenicity assessment. The correlation coefficient (r2) of the six types of BS frequencies exceeded 0.97 among the three laboratories for BP- or ENU-exposed samples. Thus, Hawk-Seq™ provides qualitatively and quantitatively reproducible results across laboratories. The OMFs in the Hawk-Seq™ analysis positively correlated (r2 = 0.64) with gpt mutant frequencies (MFs). The fold induction of OMFs in the Hawk-Seq™ analysis of ENU- and MNU-exposed samples was at least 14.2 and 4.5, respectively, compared to 6.1 and 2.5 for gpt MFs. Meanwhile, the fold induction of OMFs in BP-exposed samples was ≤ 4.6, compared to 8.2 for gpt MFs. These observations suggest that Hawk-Seq™ demonstrates good concordance with the transgenic rodent (TGR) gene mutation assay, whereas the induction of mutation frequency by each mutagen might not directly correspond. Hawk-Seq™-based whole-genome mutagenicity evaluation demonstrated high inter-laboratory reproducibility and concordance with gpt assay results. Our results contribute to the growing evidence that ecNGS assays provide a suitable, or improved, alternative to the TGR assay.

We previously investigated methods for separating mutagenic contaminants from aqueous solutions using cellulose-bearing covalently bound trisulfo-Cu-phthalocyanine (blue cotton and blue rayon). Mutagenic contaminants with three or more fused aromatic rings in their structures were adsorbed onto blue cotton and rayon. Since Cu-phthalocyanine is considered an unsuitable absorption ligand for byproducts of water chlorination, such as 3-chloro-4-(dichloromethyl)-5-hydroxy-2(5H)-furanone (Mutagen X or MX), we investigated the development of a new material for the elimination of MX from aqueous solvents. We selected green cellulose powder bearing ferrous phthalocyanine (FePh), hereafter referred to as green cellulose or GP, as the candidate material. GP is composed of cationized cellulose (white cellulose, WP) and FePh tetracarboxylic acid. The mutagenicity of MX dissolved in buffer or dimethyl sulfoxide (DMSO) solution significantly decreased after treatment with GP. The effects of GP on the elimination of MX from the solvent were very close to being expired after 70 cycles of repeated adsorption of the same GP, and the capacity of GP for MX removal was estimated to be exhausted after 120 cycles of repeated adsorption based on the extrapolation of the obtained result; thus, the interacting ligands on GP may be saturated after complete MX adsorption. The mutagenicity of MX dissolved in aqueous buffer significantly decreased after treatment at pH7.4 but not at pH 4.0. Since MX is dissociated to be the anionic form at pH 6 or higher, the negative charge of MX in the buffer at pH 7.4 may interact with the positive charge of ferrous ions in GP to create a linkage between MX and GP. After GP adsorbed MX, mutagenicity was extracted with water or acetonitrile and recovered in the eluent. Thus, the reversible interaction between MX and FePh may have caused adsorption of MX onto GP. GP could be used as a new eliminator and recovery agent for MX in chlorinated drinking water. Developing new materials for the removal and recovery of agents for the detection of mutagenic contaminant-related chlorination in water is beneficial for environmental health.

Previous research using the Ames assay showed that licoricidin (LCD) and isoliquiritigenin (ILTG) can block mutations caused by N-methyl-N-nitrosourea (MNU) in Salmonella typhimurium (S. typhimurium) TA1535. With the aim to clarify the antimutagenic mechanism of these flavonoids, we evaluated the noncovalent interactions of test compounds (LCD, ILTG, ethidium bromide (EtBr), or Hoechst 33258) with calf thymus DNA (ctDNA) using a UV-Vis spectrophotometer and quantified the DNA adducts formed when treated with a mixture of MNU and the test compounds. Additionally, we measured the half-life of MNU and the amount of each test compound remaining in the reaction mixture. The spectral and thermodynamic parameters indicated considerable binding between flavonoids (LCD and ILTG) and DNA. Intercalative EtBr and the minor-groove binder Hoechst 33258 inhibited MNU-induced mutagenicity in S. typhimurium TA1535. O6-Methylguanine (O6-MeG) and N3-methyladenine (N3-MeA) were quantified in a mixture of ctDNA and the test compounds (LCD, ILTG, EtBr, and Hoechst 33258) using LC‒MS/MS. The amount of the DNA adducts decreased with increasing concentrations of the compounds. Moreover, the half-lives of MNU were similar in the presence and absence of flavonoids (LCD and ILTG). No new products were detected, and no significant changes in the flavonoids remaining in the reaction mixture were observed, indicating that LCD and ILTG did not react directly with MNU. LCD and ILTG directly bind to DNA and suppress DNA adduct formation. However, interaction with DNA alone does not fully account for their antimutagenic activity, implying the involvement of other mechanisms.

Symposium 3 of the 53rd Annual Meeting of the Japanese Environmental Mutagen and Genome Society (JEMS), entitled "Potential for Computational Genotoxicity," was held at Shujitsu University, Okayama, Japan, on December 8, 2024. The symposium discussed the application of advanced informatics technologies, such as (quantitative) structure-activity relationship ((Q)SAR) and error-corrected next-generation sequencing (ecNGS), to the field of genotoxicity within the framework of computational genotoxicity. In this symposium, we invited three scientists who are global leaders in the field of computational genotoxicity. This report summarizes the key discussions and presentations from the symposium. The organizers hope this summary will increase awareness of computational genotoxicity.

BACKGROUND: The 5-year survival of pancreatic ductal adenocarcinoma (PDAC) remains about 10% despite therapeutic advances, underscoring the need for effective preventive and early intervention strategies. Ellagic acid (EA), a naturally occurring polyphenol, has been associated with demonstrated antitumor activity in several malignancies. However, its potential role in preventing PDAC development remains unclear. In this study, we examined the chemopreventive potential and underlying mechanisms of EA in a hamster model of PDAC induced by a high-fat diet and N-nitrosobis(2-oxopropyl)amine. RESULTS: Dietary EA (0.1% w/w) was associated with significantly reduction in both the incidence and multiplicity of PDACs compared to controls. The proportion of histologically normal pancreatic ducts increased and the Ki-67 labeling index decreased in pancreatic intraepithelial neoplasia (PanIN) following EA exposure. In vitro, cell proliferation decreased in a dose-dependent manner, G1 arrest was induced, and invasion was diminished after EA treatment. Multiplex Western blotting revealed lower inhibition of the IL-6/STAT3 pathway. The proportion of pSTAT3-positive cells in hamster PanINs and PDACs was significantly lower in the EA-treated groups than in controls. Because a high-fat diet is known to elevate adipocytokines, and resistin (Res) has been implicated in STAT3 regulation, the Res/STAT3 axis was also examined. Res-associated promotion of invasion was observed but there was no proliferation in vitro, and pSTAT3 expression did not increase. Similarly, serum Res levels did not differ significantly across groups, suggesting a limited contribution of the Res/STAT3 pathway in this hamster model. CONCLUSIONS: EA treatment was associated with reduced pancreatic carcinogenesis in vivo. The IL-6/STAT3 pathway appears to be a primary molecular target under our experimental conditions, whereas the contribution of Res is likely minimal. These findings support the potential of EA as a preventive agent against pancreatic cancer.

Echinops spinosus (ES), known as spiny globe thistle, has been widely used in traditional medicine to treat various ailments, such as splenic and renal disorders. However, the genoprotective effect of ES has not been examined previously. This report assessed the in vitro and in vivo genoprotective effects of crude extract of Echinops spinosus (CEES) and its aqueous fraction (AFES) against ethyl methanesulfonate (EMS) in mice. This study applied a battery of genotoxic endpoints, including chromosomal aberrations (CAs), the comet assay, and the micronucleus (MN) assay. Further, GC-MS and HPLC analyses were employed to identify the primary and secondary metabolites in the plant samples, respectively. Total polyphenol and flavonoid contents (TPC and TFC) were also colorimetrically measured. In vitro experiments were conducted using cultured primary mouse bone marrow and spleen. These cells were treated with two concentrations of CEES or AFES (250 and 500 µg/mL; for 24 h), followed by EMS treatment (300 µg/mL; for two hours) before the harvest. For the in vivo experiments, mice were orally administered CEES and AFES (250, 500 mg/kg; for 7 days), with or without intraperitoneal injection with EMS (300 mg/kg; for 24 h). GC-MS analysis demonstrated 25 primary metabolites in AFES, and the nitrogenous compound bis(trimethylsilyl) ethylamine was the main constituent. HPLC analysis reported 17 and 14 secondary compounds in CEES and AFES, respectively, in which chlorogenic acid was the main constituent in both samples. Colorimetric analysis showed that CEES exhibited higher TPC and TFC compared to AFES. Genotoxic results showed that EMS increased the levels of CAs and comet tail formation in vitro bone marrow and splenic cultures. Further, EMS caused chromosomal damage, as indicated by a significant increase in the frequency of CAs and MN in vivo mouse bone marrow cells. Supplementation with CEES and AFES alleviated chromosomal and DNA damage induced by EMS, and this reduction was more pronounced in vivo than in vitro experiments. High-polar constituents primarily mediated the antimutagenic activity of CEES and AFES. Meanwhile, other phytoconstituents in CEES, such as moderately polar and nonpolar constituents, synergistically potentiated the genoprotective activity, resulting in greater efficacy of CEES than AFES.

As a natural extraction, astaxanthin is gaining increasing attention because of its safety and anti-tumor properties. It has been reported to participate in the progression of various types of cancer such as gastric cancer and ovarian cancer. Nevertheless, the role of astaxanthin in nasopharyngeal carcinoma (NPC) has not been investigated. The study aimed to explore the anticancer mechanism of astaxanthin in regulating NPC cell proliferation, cell cycle progression, apoptosis, migration, and invasion. Human NPC cells (C666-1) were treated with different concentrations of astaxanthin (0, 1, 10, 20 mg/mL) followed by detection of cell viability. Then, C666-1 cell proliferation, apoptosis, cell cycle progression, invasion, and migration in response to 10 mg/mL astaxanthin, LY294002 (PI3K/AKT inhibitor) or parthenolide (PTL; NF-κB inhibitor) treatment were measured using cell counting kit-8 assay, colony forming assay, flow cytometry analyses, Transwell assay, and wound healing assay, respectively. Western blotting was performed to quantify protein levels of factors involved in PI3K/AKT and NF-κB signaling pathways, cell cycle phase markers (Cyclin D1, p21) and apoptotic markers (Bcl-2 and Bax). C666-1 cell proliferation, invasion, and migration were significantly suppressed by astaxanthin while cell apoptosis and cell cycle arrest at G1 phase were effectively enhanced in the context of 10 mg/mL astaxanthin. Protein levels of p-AKT, p-P65 and p-IκB levels were suppressed by astaxanthin treatment. After LY294002 or PTL treatment, the suppressive impact of astaxanthin on C666-1 cell process was strengthened, accompanied by the more obvious decrease in cell activity and cell colony number, more enhanced cell apoptosis and G1 phase arrest, and further inhibited cell migration and invasion. Moreover, the inhibitory effect of astaxanthin on Cyclin D1 and Bcl-2 protein levels as well as the promoting impact of astaxanthin on p21 and Bax were also amplified in combination with LY294002 or PTL treatment. Astaxanthin significantly suppresses NPC cell proliferation, cell cycle arrest, migration, invasion while promoting cell apoptosis by inactivating PI3K/AKT and NF-κB pathways. The study first reveals the anticancer role of astaxanthin in NPC, providing a potential candidate for NPC treatment.