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Considerations for Applying Route-to-Route Extrapolation to Assess the Safety of Oral Exposure to Substances. Biomolecules 2022; 13:biom13010005. [PMID: 36671390 PMCID: PMC9855723 DOI: 10.3390/biom13010005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2022] [Revised: 12/13/2022] [Accepted: 12/14/2022] [Indexed: 12/24/2022] Open
Abstract
The safety evaluation of oral exposure to substances, such as food ingredients, additives, and their constituents, relies primarily on a careful evaluation and analysis of data from oral toxicity studies. When relevant oral toxicity studies are unavailable or may have significant data gaps that make them inadequate for use in safety evaluations, data from non-oral toxicity studies in animals, such as studies on inhalation, dermal exposure, etc., might be used in support of or in place of oral toxicity studies through route-to-route (R-t-R) extrapolation. R-t-R extrapolation is applied on a case-by-case basis as it requires attention to and comparison of substance-specific toxicokinetic (TK) and toxicodynamic (TD) data for oral and non-oral exposure routes. This article provides a commentary on the utility of R-t-R extrapolation to assess the safety of oral exposure to substances, with an emphasis on the relevance of TK and systemic toxicity data.
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Human Biomonitoring Initiative (HBM4EU): Human Biomonitoring Guidance Values Derived for Dimethylformamide. TOXICS 2022; 10:toxics10060298. [PMID: 35736906 PMCID: PMC9230076 DOI: 10.3390/toxics10060298] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/22/2022] [Revised: 05/13/2022] [Accepted: 05/26/2022] [Indexed: 02/04/2023]
Abstract
Within the European Joint Program on Human Biomonitoring HBM4EU, human biomonitoring guidance values (HBM-GVs) for the general population (HBM-GVGenPop) or for occupationally exposed adults (HBM-GVWorker) are derived for prioritized substances including dimethylformamide (DMF). The methodology to derive these values that was agreed upon within the HBM4EU project was applied. A large database on DMF exposure from studies conducted at workplaces provided dose–response relationships between biomarker concentrations and health effects. The hepatotoxicity of DMF has been identified as having the most sensitive effect, with increased liver enzyme concentrations serving as biomarkers of the effect. Out of the available biomarkers of DMF exposure studied in this paper, the following were selected to derive HBM-GVWorker: total N-methylformamide (tNMF) (sum of N-hydroxymethyl-N-methylformamide and NMF) and N-acetyl-S-(N-methylcarbamoyl)cysteine (AMCC) in urine. The proposed HBM-GVWorker is 10 mg·L−1 or 10 mg·g−1 creatinine for both biomarkers. Due to their different half-lives, tNMF (representative of the exposure of the day) and AMCC (representative of the preceding days’ exposure) are complementary for the biological monitoring of workers exposed to DMF. The levels of confidence for these HBM-GVWorker are set to “high” for tNMF and “medium-low” for AMCC. Therefore, further investigations are required for the consolidation of the health-based HBM-GV for AMCC in urine.
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Liu Y, Wen C, Zhang Y, Liu Z, He Q, Cui M, Peng H, Wang Y, Zhang X, Li X, Wang Q. Aberrant expression of SNHG12 contributes to N, N-dimethylformamide-induced hepatic apoptosis both in short-term and long-term DMF exposure. Toxicol Res (Camb) 2021; 10:1022-1033. [PMID: 34733487 DOI: 10.1093/toxres/tfab088] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2021] [Revised: 07/20/2021] [Accepted: 08/08/2021] [Indexed: 12/13/2022] Open
Abstract
N, N-Dimethylformamide (DMF) can cause liver damage in occupationally exposed workers, but the molecular mechanism of DMF-induced liver damage has not been fully elucidated. Researches have proved that lncRNA plays a major function in chemical-induced liver toxicity and can be used as a biomarker and therapeutic target for liver injury. In order to verify that lncRNA also participates in DMF-induced liver damage, we treated HL-7702 cells with 75 or 150 mM DMF, and obtained lncRNA expression profiles through high-throughput sequencing. Among the differentially expressed lncRNAs, lncRNA SNHG12 was proved to be significantly downregulated in DMF-treated HL-7702 cells and participate in DMF-mediated apoptosis, even under long-term low-dose DMF exposure (5-10 mM, 8 weeks). In addition, according to bioinformatics analysis, miR-218-5p is expected to be a potential target of SNHG12, which was verified by the dual luciferase reporter assay in HEK293FT cells. MiR-218-5p mimic can induce apoptosis in HL-7702 cells. Among the predicted targets of miR-218-5p, protein kinase C epsilon (PRKCE) was reported to be involved in apoptosis, and was indeed downregulated by miR-218-5p mimic in our study. Further experiments showed that changes of the expression of SNHG12 can affect the expression of PRKCE. In the epidemiological study of occupational population, we also found that SNHG12 was downregulated in the serum exosomes of workers exposed to DMF. These results indicated that SNHG12 can mediate DMF-induced apoptosis of HL-7702 cells through miR-218-5p/PRKCE pathway.
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Affiliation(s)
- Ye Liu
- School of Public Health, Sun Yat-sen University, Guangzhou 510080, China
| | - Cuiju Wen
- Guangdong Province Hospital for Occupational Disease Prevention and Treatment, Guangzhou 510300, China
| | - Yangchun Zhang
- School of Public Health, Sun Yat-sen University, Guangzhou 510080, China
| | - Ziqi Liu
- School of Public Health, Sun Yat-sen University, Guangzhou 510080, China
| | - Qianmei He
- School of Public Health, Sun Yat-sen University, Guangzhou 510080, China
| | - Mengxing Cui
- School of Public Health, Sun Yat-sen University, Guangzhou 510080, China
| | - Honghao Peng
- School of Public Health, Sun Yat-sen University, Guangzhou 510080, China
| | - Yuqing Wang
- School of Public Health, Sun Yat-sen University, Guangzhou 510080, China
| | - Xueying Zhang
- School of Public Health, Sun Yat-sen University, Guangzhou 510080, China
| | - Xudong Li
- Guangdong Province Hospital for Occupational Disease Prevention and Treatment, Guangzhou 510300, China
| | - Qing Wang
- School of Public Health, Sun Yat-sen University, Guangzhou 510080, China
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Hsa_circ_0005915 promotes N,N-dimethylformamide-induced oxidative stress in HL-7702 cells through NRF2/ARE axis. Toxicology 2021; 458:152838. [PMID: 34153373 DOI: 10.1016/j.tox.2021.152838] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2021] [Revised: 05/29/2021] [Accepted: 06/16/2021] [Indexed: 01/02/2023]
Abstract
N,N-dimethylformamide (DMF) is an organic compound widely used in industrial production processes as a solvent with a low evaporation rate. Excessive exposure to DMF may lead to liver damage. Oxidative stress has been reported as one of the main causes of DMF-induced hepatotoxicity. Several doses of DMF (0, 1, 5, and 10 mM) were used to treat HL-7702 cells for a relatively long period to simulate the actual exposure pattern in occupational settings, and oxidative stress was induced. Previous studies illustrated that circular RNA (circRNA) plays a vital role in sustaining hepatocyte physiological function. To explore whether aberrant circRNA expression is involved in DMF-induced excessive ROS generation and hepatotoxicity, high-throughput transcriptional sequencing was performed to identify the altered circRNA expression profiles in HL-7702 liver cells after treatment with 0, 75, or 150 mM DMF for 48 h. We found that levels of induced oxidative stress were similar to those in the long-term exposure model. Among the altered circRNAs, one circRNA (hsa_circ_0005915) was significantly upregulated after DMF exposure, and it affected DMF-mediated oxidative stress in HL-7702 cells. Further experiments revealed that hsa_circ_0005915 downregulated the expression of nuclear factor erythoid-2-related factor 2 (NRF2) at the post-transcriptional level via promoting the ubiquitination and degradation of NRF2, which led to the increase of ROS accumulation. Further investigation demonstrated that the expression levels of NRF2-regulated antioxidative genes-heme oxygenase 1 (HO1) and NAD(P)H quinone dehydrogenase 1 (NQO1)-indeed declined after the overexpression of hsa_circ_0005915. In vivo study also indicated that DMF exposure can upregulate the expression of mmu_circ_0007941 (homologous circRNA of hsa_circ_0005915) and downregulated Nrf2 and Ho1 proteins. In summary, our results revealed that hsa_circ_0005915 plays an important role in promoting DMF-induced oxidative stress by inhibiting the transcriptional activity of the NRF2/ARE axis, which provides a potential molecular mechanism of DMF-mediated hepatotoxicity.
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Jiang H, Li R, Zhang Z, Chang C, Liu Y, Liu Z, He Q, Wang Q. Retinoid X receptor α (RXRα)-mediated erythroid-2-related factor-2 (NRF2) inactivation contributes to N,N-dimethylformamide (DMF)-induced oxidative stress in HL-7702 and HuH6 cells. J Appl Toxicol 2019; 40:470-482. [PMID: 31875996 DOI: 10.1002/jat.3919] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2019] [Revised: 09/18/2019] [Accepted: 09/19/2019] [Indexed: 12/24/2022]
Abstract
N,N-dimethylformamide (DMF) is a colorless industrial solvent that is frequently used for chemical reactions. Epidemiologic studies and clinical case reports have consistently indicated that the main toxic effect after exposure to DMF is hepatotoxicity. Previous studies have suggested that oxidative stress is the pivotal molecular event of DMF-mediated hepatotoxicity; however, its underlying mechanism remains unclear. In this study, we found that DMF (0-150 mM) exposure induced an increase in reactive oxygen species (ROS) levels and inhibited the transcriptional activity of nuclear factor erythroid-2-related factor-2 (NRF2) in a dose-dependent manner. Subsequently, our research revealed that the elevated ROS levels and the decline in NRF2-mediated anti-oxidative response in HL-7702 and HuH6 cells might be due to the DMF-induced accumulation of retinoid X receptor α (RXRα) protein. Further investigation demonstrated that phosphorylation of the RXRα protein, which is mediated by the activation of extracellular signal-regulated kinase (ERK), leads to the inhibition of RXRα protein degradation and in turn the accumulation of RXRα after DMF exposure. These findings provide information that improves our understanding of the role of RXRα in DMF-induced hepatotoxicity.
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Affiliation(s)
- Hongmei Jiang
- Department of Toxicology, School of Public Health, Sun Yat-sen University, Guangzhou, Guangdong, China
| | - Ruobi Li
- Department of Toxicology, School of Public Health, Sun Yat-sen University, Guangzhou, Guangdong, China
| | - Zhen Zhang
- Department of Toxicology, School of Public Health, Sun Yat-sen University, Guangzhou, Guangdong, China
| | - Chong Chang
- Department of Toxicology, School of Public Health, Sun Yat-sen University, Guangzhou, Guangdong, China
| | - Ye Liu
- Department of Toxicology, School of Public Health, Sun Yat-sen University, Guangzhou, Guangdong, China
| | - Ziqi Liu
- Department of Toxicology, School of Public Health, Sun Yat-sen University, Guangzhou, Guangdong, China
| | - Qianmei He
- Department of Toxicology, School of Public Health, Sun Yat-sen University, Guangzhou, Guangdong, China
| | - Qing Wang
- Department of Toxicology, School of Public Health, Sun Yat-sen University, Guangzhou, Guangdong, China
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Kennedy GL. Toxicology of dimethyl and monomethyl derivatives of acetamide and formamide: a second update. Crit Rev Toxicol 2012; 42:793-826. [DOI: 10.3109/10408444.2012.725028] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
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