Bibliography Tag: genotoxicity

Bibliography Index

Duforestel et al., 2019

Duforestel, Manon, Nadaradjane, Arulraj, Bougras-Cartron, Gwenola, Briand, Joséphine, Olivier, Christophe, Frenel, Jean-Sébastien, Vallette, François M., Lelièvre, Sophie A., & Cartron, Pierre-François; “Glyphosate Primes Mammary Cells for Tumorigenesis by Reprogramming the Epigenome in a TET3-Dependent Manner;” Frontiers in Genetics, 2019, 10; DOI: 10.3389/fgene.2019.00885.

ABSTRACT:

The acknowledgment that pollutants might influence the epigenome raises serious concerns regarding their long-term impact on the development of chronic diseases. The herbicide glyphosate has been scrutinized for an impact on cancer incidence, but reports demonstrate the difficulty of linking estimates of exposure and response analysis. An approach to better apprehend a potential risk impact for cancer is to follow a synergistic approach, as cancer rarely occurs in response to one risk factor. The known influence of glyphosate on estrogen-regulated pathway makes it a logical target of investigation in breast cancer research. We have used nonneoplastic MCF10A cells in a repeated glyphosate exposure pattern over 21 days. Glyphosate triggered a significant reduction in DNA methylation, as shown by the level of 5-methylcytosine DNA; however, in contrast to strong demethylating agent and cancer promoter UP peptide, glyphosate-treated cells did not lead to tumor development. Whereas UP acts through a DNMT1/PCNA/UHRF1 pathway, glyphosate triggered increased activity of ten-eleven translocation (TET)3. Combining glyphosate with enhanced expression of microRNA (miR) 182-5p associated with breast cancer induced tumor development in 50% of mice. Culture of primary cells from resected tumors revealed a luminal B (ER+/PR-/HER2-) phenotype in response to glyphosate-miR182-5p exposure with sensitivity to tamoxifen and invasive and migratory potentials. Tumor development could be prevented either by specifically inhibiting miR 182-5p or by treating glyphosate-miR 182-5p-cells with dimethyloxallyl glycine, an inhibitor of TET pathway. Looking for potential epigenetic marks of TET-mediated gene regulation under glyphosate exposure, we identified MTRNR2L2 and DUX4 genes, the hypomethylation of which was sustained even after stopping glyphosate exposure for 6 weeks. Our findings reveal that low pressure but sustained DNA hypomethylation occurring via the TET pathway primes cells for oncogenic response in the presence of another potential risk factor. These results warrant further investigation of glyphosate-mediated breast cancer risk. FULL TEXT

Stur et al., 2019

Stur, E., Aristizabal-Pachon, A. F., Peronni, K. C., Agostini, L. P., Waigel, S., Chariker, J., Miller, D. M., Thomas, S. D., Rezzoug, F., Detogni, R. S., Reis, R. S. D., Silva Junior, W. A., & Louro, I. D.; “Glyphosate-based herbicides at low doses affect canonical pathways in estrogen positive and negative breast cancer cell lines;” Plos One, 2019, 14(7), e0219610; DOI: 10.1371/journal.pone.0219610.

ABSTRACT:

Glyphosate is a broad-spectrum herbicide that is used worldwide. It represents a potential harm to surface water, and when commercially mixed with surfactants, its uptake is greatly magnified. The most well-known glyphosate-based product is Roundup. This herbicide is potentially an endocrine disruptor and many studies have shown the cytotoxicity potential of glyphosate-based herbicides. In breast cancer (BC) cell lines it has been demonstrated that glyphosate can induce cellular proliferation via estrogen receptors. Therefore, we aimed to identify gene expression changes in ER+ and ER- BC cell lines treated with Roundup and AMPA, to address changes in canonical pathways that would be related or not with the ER pathway, which we believe could interfere with cell proliferation. Using the Human Transcriptome Arrays 2.0, we identified gene expression changes in MCF-7 and MDA-MB-468 exposed to low concentrations and short exposure time to Roundup Original and AMPA. The results showed that at low concentration (0.05% Roundup) and short exposure (48h), both cell lines suffered deregulation of 11 canonical pathways, the most important being cell cycle and DNA damage repair pathways. Enrichment analysis showed similar results, except that MDA-MB-468 altered mainly metabolic processes. In contrast, 48h 10mM AMPA showed fewer differentially expressed genes, but also mainly related with metabolic processes. Our findings suggest that Roundup affects survival due to cell cycle deregulation and metabolism changes that may alter mitochondrial oxygen consumption, increase ROS levels, induce hypoxia, damage DNA repair, cause mutation accumulation and ultimately cell death. To our knowledge, this is the first study to analyze the effects of Roundup and AMPA on gene expression in triple negative BC cells. Therefore, we conclude that both compounds can cause cellular damage at low doses in a relatively short period of time in these two models, mainly affecting cell cycle and DNA repair. FULL TEXT

Lamure et al., 2019

Lamure, S., Carles, C., Aquereburu, Q., Quittet, P., Tchernonog, E., Paul, F., Jourdan, E., Waultier, A., Defez, C., Belhadj, I., Sanhes, L., Burcheri, S., Donadio, D., Exbrayat, C., Saad, A., Labourey, J. L., Baldi, I., Cartron, G., & Fabbro-Peray, P., “Association of Occupational Pesticide Exposure With Immunochemotherapy Response and Survival Among Patients With Diffuse Large B-Cell Lymphoma,” JAMA Network Open, 2019, 2(4), e192093. DOI: 10.1001/ jamanetworkopen.2019.2093.

ABSTRACT:

IMPORTANCE: Professional use of pesticides is a risk factor for non-Hodgkin lymphoma. The main biological mechanisms of pesticides and chemotherapy are genotoxicity and reactive oxygen species generation. Cellular adaptation among patients exposed to low doses of genotoxic and oxidative compounds might hinder chemotherapy efficiency in patients with lymphoma.

OBJECTIVE: To examine the association of occupational exposure to pesticides with immunochemotherapy response and survival among patients treated for diffuse large B-cell lymphoma.

DESIGN, SETTING, AND PARTICIPANTS: This retrospective cohort study assessed patients treated from July 1, 2010, to May 31, 2015, for diffuse large B-cell lymphoma, with a 2-year follow-up. The study took place at 6 university and nonuniversity hospitals in Languedoc-Roussillon, France. A total of 404 patients with newly diagnosed diffuse large B-cell lymphoma treated with anthracycline-based immunochemotherapy were included before the study began. Occupational history was reconstructed for 244 patients and analyzed with the PESTIPOP French job-exposure matrix to determine likelihood of occupational exposure to pesticides. Analysis of the data was performed from July 15, 2017, to July 15, 2018.

MAIN OUTCOMES AND MEASURES: Treatment failure (ie, partial response, stable disease, disease progression, or interruption for toxic effects) rate, 2-year event-free survival, and overall survival between exposed and nonexposed patients after adjustment for confounding factors.

RESULTS: A total of 244 patients (mean [SD] age, 61.3 [15.2] years; 153 [62.7%] male) had complete occupational data. Of these patients, 67 (27.4%) had occupational exposure to pesticides, with 38 exposed through agricultural occupations. Occupational exposure was not associated with clinical and biological characteristics at diagnosis. Occupationally exposed patients had a significantly higher treatment failure rate (22.4% vs 11.3%; P = .03; adjusted odds ratio [AOR] for confounding factors, 3.0; 95% CI, 1.3-6.9); this difference was higher among patients with exposing agricultural occupations compared with other patients (29.0% vs 11.7%; AOR, 5.1; 95% CI, 2.0-12.8). Two-year event-free survival was 70% in the occupationally exposed group vs 82% in the unexposed group (adjusted hazard ratio [AHR] for confounding factors, 2.2; 95% CI, 1.3-3.9). Among patients with exposing agricultural occupations compared with other patients, the difference was more pronounced (2-year event-free survival, 56% vs 83%; AHR, 3.5; 95% CI, 1.9-6.5). Similarly, 2-year overall survival was lower in the group of patients with exposing agricultural occupations compared with other patients (81% vs 92%; AHR, 3.9; 95% CI, 1.5-10.0).

CONCLUSIONS AND RELEVANCE: This retrospective study showed that agricultural occupational exposure to pesticides was associated with treatment failure, event-free survival, and overall survival among patients with diffuse large B-cell lymphoma. FULL TEXT

Zhang et al., 2019a

Zhang, Luoping, Rana, Iemaan, Shaffer, Rachel M., Taioli, Emanuela, & Sheppard, Lianne, “Exposure to Glyphosate-Based Herbicides and Risk for Non-Hodgkin Lymphoma: A Meta-Analysis and Supporting Evidence,” Mutation Research/Reviews in Mutation Research, In Press, 2019. DOI: 10.1016/j.mrrev.2019.02.001.

ABSTRACT:

Glyphosate is the most widely used broad-spectrum systemic herbicide in the world. Recent evaluations of the carcinogenic potential of glyphosate-based herbicides (GBHs) by various regional, national, and international agencies have engendered controversy. We investigated whether there was an association between high cumulative exposures to GBHs and increased risk of non-Hodgkin lymphoma (NHL) in humans. We conducted a new meta-analysis that included the most recent update of the Agricultural Health Study (AHS) cohort published in 2018 along with five case-control studies. Using the highest exposure groups when available in each study, we report the overall meta-relative risk (meta-RR) of NHL in GBH-exposed individuals was increased by 41% (meta-RR = 1.41, 95% CI, confidence interval: 1.13–1.75). For comparison, we also performed a secondary meta-analysis using high-exposure groups with the earlier AHS (2005), and we determined a meta-RR for NHL of 1.45 (95% CI: 1.11–1.91), which was higher than the meta-RRs reported previously. Multiple sensitivity tests conducted to assess the validity of our findings did not reveal meaningful differences from our primary estimated meta-RR. To contextualize our findings of an increased NHL risk in individuals with high GBH exposure, we reviewed available animal and mechanistic studies, which provided supporting evidence for the carcinogenic potential of GBH. We documented further support from studies of malignant lymphoma incidence in mice treated with pure glyphosate, as well as potential links between GBH exposure and immunosuppression, endocrine disruption, and genetic alterations that are commonly associated with NHL. Overall, in accordance with evidence from experimental animal and mechanistic studies, our current meta-analysis of human epidemiological studies suggests a compelling link between exposures to GBHs and increased risk for NHL. FULL TEXT

Wozniak et al., 2018

Wozniak, E., Sicinska, P., Michalowicz, J., Wozniak, K., Reszka, E., Huras, B., Zakrzewski, J., & Bukowska, B., “The mechanism of DNA damage induced by Roundup 360 PLUS, glyphosate and AMPA in human peripheral blood mononuclear cells – genotoxic risk assessement,” Food and Chemical Toxicology, 2018, 120, 510-522. DOI: 10.1016/j.fct.2018.07.035.

ABSTRACT:

Glyphosate is the most heavily applied among pesticides in the world, and thus human exposure to this substance continues to increase. WHO changed classification of glyphosate to probably cancerogenic to humans, thus there is urgent need to assess in detail genotoxic mechanism of its action. We have assessed the effect of glyphosate, its formulation (Roundup 360 PLUS) and its main metabolite (aminomethylphosphonic acid, AMPA) in the concentration range from 1 to 1000muM on DNA damage in human peripheral blood mononuclear cells (PBMCs). The cells were incubated for 24h. The compounds studied and formulation induced DNA single and double strand-breaks and caused purines and pyrimidines oxidation. None of compounds examined was capable of creating adducts with DNA, while those substances increased ROS (including (*)OH) level in PBMCs. Roundup 360 PLUS caused damage to DNA even at 5muM, while glyphosate and particularly AMPA induced DNA lesions from the concentration of 250muM and 500muM, respectively. DNA damage induced by glyphosate and its derivatives increased in order: AMPA, glyphosate, Roundup 360 PLUS. We may conclude that observed changes were not associated with direct interaction of xenobiotics studied with DNA, but the most probably they occurred through ROS-mediated effects. FULL TEXT

Varayoud et al., 2017

Varayoud, J., Durando, M., Ramos, J. G., Milesi, M. M., Ingaramo, P. I., Munoz-de-Toro, M., & Luque, E. H., “Effects of a glyphosate-based herbicide on the uterus of adult ovariectomized rats,” Environmental Toxicology, 2017, 32(4), 1191-1201. DOI: 10.1002/tox.22316.

ABSTRACT:

Glyphosate is the active ingredient of several herbicide formulations. Different reports suggest that glyphosate-based herbicides (GBHs) may act as endocrine disruptors. We evaluated the potential estrogenic effects of a GBH formulation using the uterotrophic assay. Adult ovariectomized rats were sc injected for 3 consecutive days with: saline solution (vehicle control), 2.10(-5) g E2 /kg/day (uterotrophic dose; UE2 ), 2.10(-7) g E2 /kg/day (nonuterotrophic dose; NUE2), or 0.5, 5, or 50 mg GBH/kg/day of the. Twenty-four hours after the last injection, the uterus was removed and weighed and processed for histopathology and mRNA extraction. Epithelial cell proliferation and height and expression of estrogen-responsive genes were evaluated (estrogen receptors, ERalpha and ERbeta; progesterone receptor, PR; complement 3, C3). Uterine weight and epithelial proliferation were not affected by GBH. However, the luminal epithelial cell height increased at GBH0.5. ERalpha mRNA was downregulated by all GBH doses and E2 groups, whereas PR and C3 mRNA were diminished by GBH0.5. GBH5-, GBH50-, and UE2 -treated rats showed downregulated ERalpha protein expression in luminal epithelial cells, while the receptor was upregulated in the stroma. GBH upregulated ERbeta (GBH0.5-50) and PR (GBH5) expressions in glandular epithelial cells, similar effect to that of NUE2 group. These results indicate that, although the uterine weight was not affected, GBH modulates the expression of estrogen-sensitive genes. (c) 2016 Wiley Periodicals, Inc. Environ Toxicol 32: 1191-1201, 2017.

Townsend et al., 2017

Townsend, M., Peck, C., Meng, W., Heaton, M., Robison, R., & O’Neill, K., “Evaluation of various glyphosate concentrations on DNA damage in human Raji cells and its impact on cytotoxicity,” Regulatory Toxicology and Pharmacology, 2017, 85, 79-85. DOI: 10.1016/j.yrtph.2017.02.002.

ABSTRACT:

Glyphosate is a highly used active compound in agriculturally based pesticides. The literature regarding the toxicity of glyphosate to human cells has been highly inconsistent. We studied the resulting DNA damage and cytotoxicity of various glyphosate concentrations on human cells to evaluate DNA damaging potential. Utilizing human Raji cells, DNA damage was quantified using the comet assay, while cytotoxicity was further analyzed using MTT viability assays. Several glyphosate concentrations were assessed, ranging from 15 mM to 0.1 muM. We found that glyphosate treatment is lethal to Raji cells at concentrations above 10 mM, yet has no cytotoxic effects at concentrations at or below 100 muM. Treatment concentrations of 1 mM and 5 mM induce statistically significant DNA damage to Raji cells following 30-60 min of treatment, however, cells show a slow recovery from initial damage and cell viability is unaffected after 2 h. At these same concentrations, cells treated with additional compound did not recover and maintained high levels of DNA damage. While the cytotoxicity of glyphosate appears to be minimal for physiologically relevant concentrations, the compound has a definitive cytotoxic nature in human cells at high concentrations. Our data also suggests a mammalian metabolic pathway for the degradation of glyphosate may be present. FULL TEXT

Santovito et al., 2018

Santovito, A., Ruberto, S., Gendusa, C., & Cervella, P., “In vitro evaluation of genomic damage induced by glyphosate on human lymphocytes,” Environmental Science and Pollution Research International, 2018, 25(34), 34693-34700. DOI: 10.1007/s11356-018-3417-9.

ABSTRACT:

Glyphosate is an important broad-spectrum herbicide used in agriculture and residential areas for weed and vegetation control, respectively. In our study, we analyzed the in vitro clastogenic and/or aneugenic effects of glyphosate by chromosomal aberrations and micronuclei assays. Human lymphocytes were exposed to five glyphosate concentrations: 0.500, 0.100, 0.050, 0.025, and 0.0125 mug/mL, where 0.500 mug/mL represents the established acceptable daily intake value, and the other concentrations were tested in order to establish the genotoxicity threshold for this compound. We observed that chromosomal aberration (CA) and micronuclei (MNi) frequencies significantly increased at all tested concentrations, with exception of 0.0125 mug/mL. Vice versa, no effect has been observed on the frequencies of nuclear buds and nucleoplasmic bridges, with the only exception of 0.500 mug/mL of glyphosate that was found to increase in a significant manner the frequency of nucleoplasmic bridges. Finally, the cytokinesis-block proliferation index and the mitotic index were not significantly reduced, indicating that glyphosate does not produce effects on the proliferation/mitotic index at the tested concentrations. FULL TEXT

Rice et al., 2018

Rice, J.R., Dunlap, P., Ramaiahgari, S., Ferguson, S., Smith-Roe, S.L., & DeVito, M., “Poster: Effects of Glyphosate and its Formulations on Markers of Oxidative Stress and Cell Viability in HepaRG and HaCaT Cell Lines, 2018, Presented at the Society of Toxicology Conference.

ABSTRACT:

Glyphosate (GLY) is the active ingredient found in herbicide formulations worldwide. GLY is toxic to plants by disrupting the shikimate amino acid synthesis pathway. The present day intensive use of GLY began with the introduction of GLY-resistant crops in the late 1990s. Although GLY has a low toxicity profile for humans and mammals, conflicting reports exist as to whether it poses a cancer risk for humans. The USEPA and European regulatory agencies have described GLY as unlikely to pose a carcinogenic hazard to humans. However, the International Agency for Research on Cancer (IARC) has classified GLY as “probably carcinogenic to humans”.

IARC proposed that oxidative stress may be a mechanism by which GLY could potentially cause cancer. To address this hypothesis, we are testing GLY in human cell lines using several assays that detect reactive oxygen species (ROS) or their effects. Studies were designed to compare the point of departure for the effects of GLY on cell viability (CellTiter-Glo assay) to the point of departure for effects in oxidative damage assays. We also directly compared the effects of GLY versus GLY salts, as well as GLY and adjunct active ingredients versus formulations. We used a high content, 384-well plate approach to generate extensive dose-response curves for multiple comparisons.

Assays (CellTiter-Glo, ROS-Glo, and JC10) were performed after 1 or 24 h of exposure to test articles. GLY and GLY isopropylamine decreased cell viability and altered mitochondrial membrane potential (MMP) at ≥ 10 mM, but did not affect ROS production. The formulations were more potent than GLY alone. Cell viability and MMP were significantly altered at 1 h by the formulations. Based on GLY concentrations, these mixtures were over 1000x more potent than GLY alone. In contrast to the robust induction of ROS by positive controls at both time points, formulations had no effect on ROS at 1 h and showed a marginal increase in ROS at 24 h. These data suggest that GLY does not induce oxidative stress. In addition, the formulations marginally increased oxidative stress only after significant loss of cell viability. The results were very similar for both HepaRG and HaCaT cell lines, suggesting that xenobiotic metabolism has little impact on cell viability and oxidative stress induced by these chemicals. FULL TEXT

Milic et al., 2018

Milic, Mirta, Zunec, Suzana, Micek, Vedran, Kasuba, Vilena, Mikolic, Anja, Lovakovic, Blanka Tariba, Semren, Tanja Zivkovic, Pavicic, Ivan, Cermak, Ana Marija Marjanovic, Pizent, Alica, Vrdoljak, Ana Lucic, Valencia-Quintana, Rafael, Sanchez-Alarcon, Juana, & Zeljezic, Davor, “Oxidative stress, cholinesterase activity, and DNA damage in the liver, whole blood, and plasma of Wistar rats following a 28-day exposure to glyphosate,” Archives of Industrial Hygiene and Toxicology, 2018, 69(2), 154-168. DOI: 10.2478/aiht-2018-69-3114.

ABSTRACT:

In this 28 day-study, we evaluated the effects of herbicide glyphosate administered by gavage to Wistar rats at daily doses equivalent to 0.1 of the acceptable operator exposure level (AOEL), 0.5 of the consumer acceptable daily intake (ADI), 1.75 (corresponding to the chronic population-adjusted dose, cPAD), and 10 mg kg-1 body weight (bw) (corresponding to 100 times the AOEL). At the end of each treatment, the body and liver weights were measured and compared with their baseline values. DNA damage in leukocytes and liver tissue was estimated with the alkaline comet assay. Oxidative stress was evaluated using a battery of endpoints to establish lipid peroxidation via thiobarbituric reactive substances (TBARS) level, level of reactive oxygen species (ROS), glutathione (GSH) level, and the activity of glutathione peroxidase (GSH-Px). Total cholinesterase activity and the activities of acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) were also measured. The exposed animals gained less weight than control. Treatment resulted in significantly higher primary DNA damage in the liver cells and leukocytes. Glyphosate exposure significantly lowered TBARS in the liver of the AOEL, ADI, and cPAD groups, and in plasma in the AOEL and cPAD group. AChE was inhibited with all treatments, but the AOEL and ADI groups significantly differed from control. Total ChE and plasma/liver ROS/GSH levels did not significantly differ from control, except for the 35 % decrease in ChE in the AOEL and ADI groups and a significant drop in liver GSH in the cPAD and 100xAOEL groups. AOEL and ADI blood GSH-Px activity dropped significantly, but in the liver it significantly increased in the ADI, cPAD, and 100xAOEL groups vs. control. All these findings show that even exposure to low glyphosate levels can have serious adverse effects and points to a need to change the approach to risk assessment of low-level chronic/sub-chronic glyphosate exposure, where oxidative stress is not necessarily related to the genetic damage and AChE inhibition. FULL TEXT

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