Mutagenesis最新文献

Gut barrier dysfunction and related inflammation are known to be associated with the development and progression of colorectal cancer (CRC). We investigated associations of 292 single-nucleotide polymorphisms (SNPs) from 27 genes related to endotoxins/lipopolysaccharide (LPS) sensing and tolerance, mucin synthesis, inflammation, and Crohn's disease with colon and rectal cancer risks. Incident CRC cases (N=1,374; colon=871, rectum=503) were matched 1:1 to controls nested within the European Prospective Investigation into Cancer and Nutrition cohort. Previously measured serum concentrations of gut barrier function and inflammation biomarkers (flagellin/LPS-specific immunoglobulins and C-reactive protein [CRP]) were available for a sub-set of participants (Ncases=1,001; Ncontrols=667). Forty-two unique SNPs from 19 different genes were associated with serum biomarkers at Punadjusted≤0.05 among controls. Among SNPs associated with a gut permeability score, 24 SNPs were in genes related to LPS sensing and mucin synthesis. Nine out of 12 SNPs associated with CRP were in genes related to inflammation or Crohn's disease. TLR4 was associated with colon cancer at the SNP level (nine SNPs, all Punadjusted≤0.04) and at the gene level (Punadjusted≤0.01). TLR4 rs10759934 was associated with rectal cancer but not colon cancer. Similarly, IL10 was associated with rectal cancer risk at a SNP and gene level (both Punadjusted ≤ 0.01), but not colon cancer. Genes and SNPs were selected a priori therefore we present unadjusted P-values. However, no association was statistically significant after multiple testing correction. This large and comprehensive study has identified gut barrier function and inflammation-related genes possibly contributing to CRC risk in European populations and is consistent with potential etiological links between host genetic background, gut barrier permeability, microbial endotoxemia and CRC development.

Nonspecific structural chromosomal aberrations (CAs) are found in around 1% of circulating lymphocytes from healthy individuals but the frequency may be higher after exposure to carcinogenic chemicals or radiation. CAs have been used in the monitoring of persons exposed to genotoxic agents and radiation. Previous studies on occupationally exposed individuals have shown associations between the frequency of CAs in peripheral blood lymphocytes and subsequent cancer risk. The cause for CA formation are believed to be unrepaired or insufficiently repaired DNA double-strand breaks or other DNA damage, and additionally telomere shortening. CAs include chromosome (CSAs) and chromatid type aberrations (CTAs). In the present review, we first describe the types of CAs, the conventional techniques used for their detection and some aspects of interpreting the results. We then focus on germline genetic variation in the frequency and type of CAs measured in a genome-wide association study (GWAS) in healthy individuals in relation to occupational and smoking-related exposure compared to non-exposed referents. The associations (at p<10-5) on 1473 healthy individuals were broadly classified in candidate genes from functional pathways related to DNA damage response/repair, including PSMA1, UBR5, RRM2B, PMS2P4, STAG3L4, BOD1, COPRS and FTO; another group included genes related to apoptosis, cell proliferation, angiogenesis and tumorigenesis, COPB1, NR2C1, COPRS, RHOT1, ITGB3, SYK, and SEMA6A; a third small group mapped to genes KLF7, SEMA5A and ITGB3 which were related to autistic traits, known to manifest frequent CAs. Dedicated studies on 153 DNA repair genes showed associations for some 30 genes, expression of which could be modified by the implicated variants. We finally point out that monitoring of CAs is so far the only method of assessing cancer risk in healthy human populations, and the use of the technology should be made more attractive by developing automated performance steps and incorporating artificial intelligence methods into the scoring.

Several bioactive compounds, such as polyphenols, demonstrate low toxicity and prominent effects on cancer cells with antioxidant, anti-inflammatory, and antitumor activities. Such compounds can be found in Amazon mosses Leucobryum martianum (Hornsch.) Hampe ex Müll. Hal. (Hornsch.) and Leucobryum laevifolium (Broth). Antimutagenic assay with Salmonella enterica serovar Typhimurium and cytotoxicity with different eukaryotic cell lines were carried out to screen aqueous, hydroalcoholic, and ethanolic extracts of those Amazon mosses for anticancer potential. The results indicate the capacity of all extracts of both mosses to exert chemopreventive effects against 4-nitroquinoline-N-oxide (4NQO) and 2-aminoanthracene (2-AA), which are direct or indirect mutagens. In particular, the ethanolic and aqueous extract from L. martianum. The ethanolic extract from L. martianum induces significant cytotoxicity by mitochondrial metabolism and cell membrane disruption pathways to tumor or non-tumor cells. The aqueous extract from L. martianum showed a mainly cytotoxic response in the HepG2 cells, a human liver carcinoma, reaching ~90% cytotoxicity. The same extract did not induce significant damage to normal liver cells (F C3H cells) by membrane interaction pathway. The selective cytotoxicity in the aqueous extract of L. martianum makes it a candidate against liver cancer. Further studies, including in vivo models, are necessary to validate the efficacy and safety of the aqueous extract of L. martianum.

DNA oxidation is a serious threat to genome integrity and is involved in mutations and cancer initiation. The G base is most frequently damaged, and 8-oxo-7,8-dihydroguanine (GO, 8-hydroxyguanine) is one of the predominant damaged bases. In human cells, GO causes a G:C→T:A transversion mutation at the modified site, and also induces untargeted substitution mutations at the G bases of 5'-GpA-3' dinucleotides (action-at-a-distance mutations). The 5'-GpA-3' sequences are complementary to the 5'-TpC-3' sequences, the preferred substrates for apolipoprotein B mRNA-editing enzyme, catalytic polypeptide-like 3 (APOBEC3) cytosine deaminases, and thus their contribution to mutagenesis has been considered. In this study, APOBEC3B, the most abundant APOBEC3 protein in human U2OS cells, was knocked down in human U2OS cells, and a GO-shuttle plasmid was then transfected into the cells. The action-at-a-distance mutations were reduced to ~25% by the knockdown, indicating that GO-induced action-at-a-distance mutations are highly dependent on APOBEC3B in this cell line.

Somatic DNA damage and causative factors (occupational exposures, foods, habits, etc.) are thought to contribute to the pathogenesis of atherosclerosis, although knowledge about their role in coronary artery disease (CAD) is still insufficient. This study aimed to determine the effects of lymphocyte-DNA damage and blood trace element concentrations on CAD. The single-cell alkaline comet was used in the measuring of the lymphocyte DNA damage in blood samples obtained from patients (n = 99) whose CAD grade was determined by the syntax score while the angiographic intervention was carried out. Blood trace element (n = 14) concentrations were monitored by the inductively coupled plasma-optical emission spectroscopy (ICP-OES) after microwave digestion. The relationship between the DNA damage frequencies of the participants and their syntax scores, blood trace element concentrations, and other demographic and clinic parameters were statistically analyzed. Significant correlations were detected between comet data and syntax score (r = 0.858, P < .001), age (r = 0.337, P < .001), blood-urea (r = 0.360, P < .001), creatinine (r = 0.388, P < .001), HbA1c (0.218, P < .05), ECG-QRS time (r = 0.286, P < .01), ECHO-EF (r = -0.377, P < .001), and platelet (r = -0.222, P < .05). The DNA damage frequencies of the groups formed according to their CAD scores were significantly different from the control group (P < .001) and also each other (P ≤ .01). Comet frequencies and CAD grades were found to be correlated with aging (P < .05). DNA damage frequency and syntax score values were significantly (P < .05) higher in males compared to females. Syntax scores were correlated with aging (r = 0.348, P < .01), ECHO-EF (r = 0.374, P < .001), blood-urea (r = 0.398, P < .001), creatinine (r = 0.433, P < .001), glucose (0.218, P < .05), and HbA1c (r = 0.200, P < .05). Significant correlations were observed between trace elements and demographic values, blood parameters, diseases, angio parameters, ECHO, and ECG parameters. It was observed that the concentrations of trace elements detected in the blood were 93.4% correlated with each other. Lymphocyte DNA damage is a strong biomarker for the atherosclerotic indicator of CAD. Aging is an effective factor both in the DNA damage frequency and CAD risk index. Creatinine and urea are factors that have the power to change the CAD risk index and DNA damage frequency. The higher DNA damage and CAD risk were monitored in males compared to females. The relationship between some biomarkers and blood trace element concentrations showed that further studies are needed to more accurately evaluate the relationship between trace elements, DNA damage frequencies, and CAD.

The translocation of mitochondrial DNA (mtDNA) sequences into the nuclear genome, resulted in the occurrence of nuclear sequences of mitochondrial origin (NUMTs) which can be detected in nearly all sequenced eukaryotes. However, de novo mtDNA insertions can contribute to the development of pathological conditions including cancer. Recent data indicate that de novo mtDNA translocation into chromosomes can occur due to genotoxic influence of DNA double-strand break-inducing environmental mutagens. This confirms the hypothesis of the involvement of genome instability in the occurrence of mtDNA fragments in chromosomes. Mounting evidence indicates that mitochondria can be transferred from normal cells to cancer cells and recover cellular respiration. These exchanged mitochondria can facilitate cancer progression and metastasis. This review article provides a comprehensive overview of the potential carcinogenicity of mtDNA insertions, and the relevance of mtDNA escape in cancer progression, metastasis, and treatment resistance in humans. Potential molecular targets involved in mtDNA escape and exchange of mitochondria that can be of possible clinical benefits are presented and discussed. Understanding these processes could lead to improved diagnostic approaches, novel therapeutic strategies, and a deeper understanding of the intricate relationship between mitochondria, nuclear DNA, and cancer biology.

The quinolizidine alkaloids matrine and its N-oxide oxymatrine occur in plants of the genus Sophora. Recently, matrine was sporadically detected in liquorice products. Morphological similarity of the liquorice plant Glycyrrhiza glabra with Sophora species and resulting confusion during harvesting may explain this contamination, but use of matrine as pesticide has also been reported. The detection of matrine in liquorice products raised concern as some studies suggested a genotoxic activity of matrine and oxymatrine. However, these studies are fraught with uncertainties, putting the reliability and robustness into question. Another issue was that Sophora root extracts were usually tested instead of pure matrine and oxymatrine. The aim of this work was therefore to determine whether matrine and oxymatrine have potential for causing gene mutations. In a first step and to support a weight-of-evidence analysis, in silico predictions were performed to improve the database using expert and statistical systems by VEGA, Leadscope (Instem®), and Nexus (Lhasa Limited). Unfortunately, the confidence levels of the predictions were insufficient to either identify or exclude a mutagenic potential. Thus, in order to obtain reliable results, the bacterial reverse mutation assay (Ames test) was carried out in accordance with OECD Test Guideline 471. The test set included the plate incorporation and the preincubation assay. It was performed with five different bacterial strains in the presence or absence of metabolic activation. Neither matrine nor oxymatrine induced a significant increase in the number of revertants under any of the selected experimental conditions. Overall, it can be concluded that matrine and oxymatrine are unlikely to have a gene mutation potential. Any positive findings with Sophora extracts in the Ames test may be related to other components. Notably, the results also indicated a need to extend the application domain of respective (Q)SAR tools to secondary plant metabolites.

Cadmium chloride (CdCl2) is a known genotoxic carcinogen, with a mechanism of action thought to partly involve the generation of reactive oxygen species (ROS). We applied here a multi-endpoint approach in vitro to explore the impact of CdCl2 on both the genome and on wider cell biology pathways relevant to cancer. Multi-endpoint approaches are believed to offer greater promise in terms of understanding the holistic effects of carcinogens in vitro. This richer understanding may help better classification of carcinogens as well as allowing detailed mechanisms of action to be identified. We found that CdCl2 caused DNA damage [micronuclei (MN)] in both TK6 and NH32 cells in a dose-dependent manner after 4 h exposure (plus 23 h recovery), with lowest observable effect levels (LOELs) for MN induction of 1 μM (TK6) and 1.6 μM (NH32). This DNA damage induction in TK6 cells was ROS dependent as pretreatment with the antioxidant N-Acetyl Cysteine (1 mM), abrogated this effect. However, 2',7'-dichlorofluorescin diacetate was not capable of detecting the ROS induced by CdCl2. The use of NH32 cells allowed an investigation of the role of p53 as they are a p53 null cell line derived from TK6. NH32 showed a 10-fold increase in MN in untreated cells and a similar dose-dependent effect after CdCl2 treatment. In TK6 cells, CdCl2 also caused activation of p53 (accumulation of total and phosphorylated p53), imposition of cell cycle checkpoints (G2/M) and intriguingly the production of smaller and more eccentric (elongated) cells. Overall, this multi-endpoint study suggests a carcinogenic mechanism of CdCl2 involving ROS generation, oxidative DNA damage and p53 activation, leading to cell cycle abnormalities and impacts of cell size and shape. This study shows how the integration of multiple cell biology endpoints studied in parallel in vitro can help mechanistic understanding of how carcinogens disrupt normal cell biology.

Hepatic leukemia factor (HLF), a transcription factor, is dysregulated in many cancers. This study investigates the function of HLF in prostate cancer (PCa) and its relation to tensin 1 (TNS1). Clinical tissues were collected from 24 PCa patients. Duke University 145 (DU145) and PC3 cells overexpressing HLF were established. HLF signaling was downregulated in PCa tissues compared to adjacent tissues and in DU145 and PC3 cells compared to prostate epithelial cells RWPE-1 or prostate stromal cells (WPMY-1). PCa cell lines with overexpression of HLF had reduced proliferative, migratory, and invasive activity, increased apoptosis, and cell mitosis mostly in the G0/G1 phase. HLF induced the TNS1 transcription to activate the p53 pathway. Depletion of TNS1 reversed the anti-tumor effects of HLF on PCa cells and tumor growth and metastasis in vivo. In summary, our findings suggest that HLF suppressed PCa progression by upregulating TNS1 expression and inducing the p53 pathway activation, which might provide insights into novel strategies for combating PCa.