Mutagenesis最新文献

The in vitro Bacterial Reverse Mutation (Ames) Test is crucial for evaluating the mutagenicity of pharmaceutical impurities. For N-nitrosamines (NAs) historical data indicated that for certain members of this chemical class the outcomes of the Ames Test did not correlate with their associated rodent carcinogenicity outcomes. This has resulted in negative outcomes in an OECD aligned Ames Test alone (standard or enhanced) no longer being considered sufficient by regulatory authorities to assess potential carcinogenic risk of NAs if present as impurities in drug products. Consequently, extensive follow-up in vivo testing can be required to characterise the potential mutagenicity and genotoxic carcinogenicity of NA impurities (i.e., beyond that defined in the ICH M7 guideline for non-NA impurities). We previously demonstrated that the mutagenicity of alkyl-nitrosamines can be detected by the appropriately designed, OECD aligned Ames Test and identified those conditions that contributed most to assay sensitivity. This OECD aligned Ames Test design was used to assess seven NAs, i.e. (methyl(neopentyl)nitrosamine, N-methyl-N-nitroso-2-propanamine, N-nitrosodiisopropylamine, bis(2-methoxyethyl)nitrosoamine, N-nitroso-N-methyl-4-fluoroaniline, dinitrosoethambutol, (R,R)- and mononitrosocaffeidine) that were reported to be negative in historical Ames Tests but positive in rodent carcinogenicity studies. All seven of the NAs were demonstrated to be mutagenic in the OECD aligned Ames test and therefore these compounds should no longer be considered as discordant (false negatives) with respect to the correlation of the Ames Test and rodent carcinogenicity. These results confirm the sensitivity of the OECD aligned Ames Test for the detection of NA mutagenicity and provides further support of its pivotal placement within the ICH M7 framework for the assessment of mutagenic impurities in pharmaceuticals to limit potential carcinogenic risk. In addition, we present data for 1-cyclopentyl-4-nitrosopiperazine, that indicates it could serve as a suitable positive control to provide further confidence in the sensitivity of the Ames Test for the NA chemical class.

The proceedings of the 36th annual meeting of the Industrial Genotoxicology Group (IGG) are shared here. The meeting held at Lhasa Limited, Leeds, UK on 28th November 2023, focussed two aspects; New Approach Methodologies (NAM's), including those for the assessment of non-standard modalities such as gas-vapour assessments and nanomaterials, and addressing the regulatory challenges associated with understanding the genotoxic and carcinogenic potential of N-nitrosamines and N-nitrosamine impurities. New approach methodologies, such as error-corrected sequencing and enhanced Ames tests that may help address these challenges were also discussed.

Colorectal cancer is a global killer that causes approximately 940 thousand deaths annually. Terminalia ivorensis (TI) is a tropical tree, the bark of which is used in African traditional medicine for the treatment of diabetes, malaria and ulcer. This study investigated TI as a potential anticancer agent in human colon cells in vitro. TI was extracted sequentially with petroleum ether, chloroform, ethyl acetate and ethanol. Antioxidant activity was assessed by DPPH and FRAP, and differential effects on cell viability, growth, DNA damage, DNA repair, and migration were measured in human colon cancer cells (CaCo-2) and/or non-cancerous human colonocytes (NCM460). The TI phytochemicals most strongly associated with these effects were identified by partial least-squares discriminant analysis. DPPH and FRAP activity were highest in TI ethyl acetate and ethanol extracts (p=0.001). All TI extracts significantly inhibited cell viability and growth and induced DNA damage and inhibited DNA repair in both cell models. The majority of TI extracts were significantly (p=0.01) more toxic to cancer cells than non-cancerous colonocytes. DNA repair was significantly (p=0.001) inhibited in CaCo-2 cells by ethyl acetate extract compared with NCM460 cells. Migration was also significantly inhibited (p<0.001) in CaCo-2 by ethyl acetate (80%) and ethanol extracts (75%). Specific benzoic acids, flavonoids and phenols were identified to be strongly associated with these effects. TI displayed strong antioxidant activity and specific anticancer effects by inducing cell death and DNA damage, and by inhibiting DNA repair, cell proliferation and migration.

Doxorubicin, a well-known and widely used antineoplastic agent with direct ROS-accumulating activity, has proven effective in treating various cancer types. However, its non-specific cytotoxicity towards non-cancerous cells prompts concerns regarding potential adverse effects. Azithromycin is an antibiotic for treating bacterial infections and an anti-inflammatory agent, particularly beneficial in managing respiratory conditions like bronchitis and sinusitis. Despite azithromycin's well-documented antibacterial properties, its potential cellular/genomic protective effects remain unexplored. As an in vitro model, BEAS-2B cells (normal human bronchial epithelium cells) were employed in the present study to assess whether azithromycin possesses any protective properties against doxorubicin-induced cellular toxicity. Cells in pre-treatment culture were treated to various amounts of azithromycin (3.125, 6.25, 12.5, 25, and 50 μg/mL) in combination with doxorubicin at IC50 (0.08 μg/mL). Doxorubicin at 0.08 μg/mL highlighted cytotoxicity, oxidative stress, and genotoxicity. Azithromycin at 25 and 50 μg/mL markedly modulated oxidative stress and genomic damage by decreasing the ROS and LPO amounts, and suppressing DNA fragmentation in the comet assay parameters. Consequently, azithromycin may be regarded as a cytomodulating, antigenotoxic, and antioxidant agent.

The purposes of this review were to investigate the application of the comet assay in Allium cepa root cells to assess the genotoxicity of environmental samples and to analyse the experimental procedures employed. A literature search was performed selecting articles published between January 2000 and October 2023 from online databases using the combined search terms 'comet assay' and 'A. cepa'. Only 18 papers met the inclusion criteria. None of these were published in the first eight years (2000-2007), highlighting the increasing interest in using the comet assay on A. cepa to analyse environmental samples over the last decade. The majority of the selected studies (15/18, 83%) were performed on samples belonging to the water compartment on onion bulbs. Half of the selected studies (9/18) were conducted to demonstrate the DNA damaging effect of the sample, while the other half of the studies not only recognized the presence of genotoxic agents but also addressed possible remediation measures. Detailed analysis of the experimental procedures revealed heterogeneity in many key steps, such as exposure time, test controls, nuclei isolation solutions, duration of electrophoresis, and number of nuclei scored. This literature review has shown that the comet assay on A. cepa, although recognized as an appropriate tool, is underutilized in environmental toxicology. Greater standardization could lead to its more widespread use, providing valuable information on the genotoxicity of environmental samples and the ability of different processes to mitigate their negative effects on plants.

Diagnostic performance of molecular markers in surrogate tissues like stool may be affected by colorectal cancer (CRC) morphological heterogeneity. The mucinous histotype represents a subgroup of CRC with a peculiar molecular program and unfavorable disease progression. However, the percentage of mucinous morphology necessary to define this subtype is still a matter of debate. In this study, we investigated whether stool miRNA profiles of CRC patients differ in patients with mucinous histopathological subtypes compared to non-mucinous cancers. In this respect, we also explored how the stool miRNA signature reported in our previous multicentric study (Pardini et al., Gastroenterology 2023) behave in this histotype. Small-RNA sequencing was performed in fecal and tissue samples of an Italian cohort (n=172), including 27 CRC with mucinous morphology (mucinous cancers with >50% mucinous morphology and those with mucinous component >5% but <50%), 58 non-mucinous CRC, and 87 colonoscopy-negative controls. Results were compared with fecal miRNA profiles of a cohort from the Czech Republic (n=98). Most of the differentially expressed (DE) stool miRNAs (n=324) were in common between CRC with mucinous morphology and non-mucinous histopathological subtypes in comparison with healthy controls. Interestingly, the altered levels of 25 fecal miRNAs previously identified distinguishing CRC cases from controls in both cohorts were also confirmed after stratification for mucinous morphology. Forty-nine miRNAs were DE exclusively in CRC with mucinous morphology and 61 in non-mucinous CRC. Mucinous cancers and those with mucinous component showed fairly similar profiles that were comparable in the Czech cohort. Among the stool DE miRNAs observed in CRC with mucinous morphology, 20 were also altered in the comparison between tumor and adjacent mucosa tissue. This study highlights miRNAs specifically altered in CRC with mucinous morphology. Nevertheless, the performance of our stool miRNA signature in accurately distinguishing CRC cases from controls was not significantly affected by this histological subtype. This aspect further supports the use of stool miRNAs for noninvasive diagnosis and screening strategies.

The therapeutic potential of the human genome has been explored through the development of next-generation therapeutics, which have had a high impact on treating genetic disorders. Classical treatments have traditionally focused on common diseases that require repeated treatments. However, with the recent advancements in the development of nucleic acids, utilizing DNA and RNA to modify or correct gene expression in genetic disorders, there has been a paradigm shift in the treatment of rare diseases, offering more potential one-time cure options. Advanced technologies that use CRISPR-Cas 9, antisense oligonucleotides, siRNA, miRNA, and aptamers are promising tools that have achieved successful breakthroughs in the treatment of various genetic disorders. The advancement in the chemistry of these molecules has improved their efficacy, reduced toxicity, and expanded their clinical use across a wide range of tissues in various categories of human disorders. However, challenges persist regarding the safety and efficacy of these advanced technologies in translating into clinical practice. This review mainly focuses on the potential therapies for rare genetic diseases and considers how next-generation techniques enable drug development to achieve long-lasting curative effects through gene inhibition, replacement, and editing.

The current Organisation for Economic Co-Operation and Development test guideline number 487 (OECD TG No. 487) provides instruction on how to conduct the in vitro micronucleus assay. This assay is one of the gold standard approaches for measuring the mutagenicity of test items; however, it is directed at testing low molecular weight molecules and may not be appropriate for particulate materials (e.g. engineered nanoparticles [ENPs]). This study aimed to adapt the in vitro micronucleus assay for ENP testing and underpins the development of an OECD guidance document. A harmonized, nano-specific protocol was generated and evaluated by two independent laboratories. Cell lines utilized were human lymphoblastoid (TK6) cells, human liver hepatocytes (HepG2) cells, Chinese hamster lung fibroblast (V79) cells, whole blood, and buffy coat cells from healthy human volunteers. These cells were exposed to reference ENPs from the Joint Research Council (JRC): SiO2 (RLS-0102), Au5nm and Au30nm (RLS-03, RLS-010), CeO2 (NM212), and BaSO4 (NM220). Tungsten carbide-cobalt (WC/Co) was used as a trial particulate positive control. The chemical controls were positive in all cell cultures, but WC/Co was only positive in TK6 and buffy coat cells. In TK6 cells, mutagenicity was observed for SiO2- and both Au types. In HepG2 cells, Au5nm and SiO2 showed sub-two-fold increases in micronuclei. In V79 cells, whole blood, and buffy coat cells, no genotoxicity was detected with the test materials. The data confirmed that ENPs could be tested with the harmonized protocol, additionally, concordant data were observed across the two laboratories with V79 cells. WC/Co may be a suitable particulate positive control in the in vitro micronucleus assay when using TK6 and buffy coat cells. Detailed recommendations are therefore provided to adapt OECD TG No. 487 for testing ENP.