Activation of the Nrf2 signaling pathway in usnic acid-induced toxicity in HepG2 cells

Chen, Si; Zhang, Zhuhong; Qing, Tao; Ren, Zhen; Yu, Dianke; Couch, Letha H.; Mei, Nan; Shi, Leming; Tolleson, William H.; Guo, Lei

doi:10.1007/s00204-016-1775-y

Cited by 40 publications

(22 citation statements)

References 59 publications

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“…Previous studies demonstrated that several key mechanisms of drug induced liver toxicity such as mitochondrial dysfunction, apoptosis, and ER stress are mediated by the MAPK signaling pathway (Chen et al, 2017; Ren et al, 2016). In the current study, another important finding is that the activation of JNK and ERK1/2, two branches of the MAPK cascade, contributes to the toxicity of leflunomide.…”

Section: Discussionmentioning

confidence: 99%

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Endoplasmic reticulum stress and MAPK signaling pathway activation underlie leflunomide-induced toxicity in HepG2 Cells

et al. 2017

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Leflunomide, used for the treatment of rheumatoid arthritis, has been reported to cause severe liver problems and liver failure; however, the underlying mechanisms are not clear. In this study, we used multiple approaches including genomic analysis to investigate and characterize the possible molecular mechanisms of the cytotoxicity of leflunomide in hepatic cells. We found that leflunomide caused endoplasmic reticulum (ER) stress and activated an unfolded protein response, as evidenced by increased expression of related genes including CHOP and GADD34; and elevated protein levels of typical ER stress markers including CHOP, ATF-4, p-eIF2α, and spliced XBP1. The secretion of Gaussia luciferase was suppressed in cells treated with leflunomide in an ER stress reporter assay. Inhibition of ER stress with an ER stress inhibitor 4-phenylbutyrate, and knockdown of ATF-4 and CHOP genes partially protected cells upon leflunomide exposure. In addition, both genomic and biochemical analyses revealed that JNK and ERK1/2 of MAPK signaling pathways were activated, and both contributed to the leflunomide-induced cytotoxicity. Inhibiting JNK activation using a JNK inhibitor attenuated the ER stress and cytotoxicity of leflunomide, whereas inhibiting ERK1/2 using an ERK1/2 inhibitor or ERK1/2 siRNA increased the adverse effect caused by leflunomide, suggesting opposite roles for the two pathways. In summary, our data indicate that both ER stress and the activation of JNK and ERK1/2 contribute to leflunomide-induced cytotoxicity.

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Section: Discussionmentioning

confidence: 99%

“…RNA-seq libraries were constructed and sequenced using the TruSeq protocol on an Illumina HiSeq 2000 platform. Data analysis was as described previously (Chen et al, 2017). The read counts for each sample were normalized as reads per million mapped reads (RPM) and transformed to log 2 scale for further analysis.…”

Section: Methodsmentioning

confidence: 99%

Endoplasmic reticulum stress and MAPK signaling pathway activation underlie leflunomide-induced toxicity in HepG2 Cells

et al. 2017

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“…Intracellular ROS production was measured as described previously (Chen et al 2017). Briefly, cells were seeded in 96-well plates; after 12 h, cells were treated with 10 μM H 2 DCF-DA for 45 min at 37 °C in the dark, and then they were washed with PBS to remove unincorporated dye.…”

Section: Methodsmentioning

confidence: 99%

ROS generation and JNK activation contribute to 4-methoxy-TEMPO-induced cytotoxicity, autophagy, and DNA damage in HepG2 cells

et al. 2017

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4-Methoxy-TEMPO, a derivative of 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO), is a stable nitroxide radical and is generally used in organic and pharmaceutical syntheses for the oxidation of alcohols. Previously, we reported the involvement of reactive oxygen species (ROS) and c-Jun N-terminal kinases (JNK) in TEMPO-induced apoptosis in mouse L5178Y cells. In this study, we investigated 4-methoxy-TEMPO induced toxicity in human HepG2 hepatoma cells and its underlying mechanisms. Treatments with 4-methoxy-TEMPO (0.5–5 mM for 2–6 h) caused oxidative stress as demonstrated by increased intensity of the ROS indicator H2DCF-DA, decreased levels of glutathione. 4-Methoxy-TEMPO treatment also induced DNA damage as characterized by increased levels of DNA tail intensity in the Comet assay, increased phosphorylation of related proteins including γ-H2A.X, p-Chk1, and p-Chk2, and activation of MAPK signaling pathways. In addition, 4-methoxy-TEMPO also induced autophagy as demonstrated by the conversion of LC3B-I to II, decreased level of p62, and the appearance of GFP-LC3B punctae. To investigate the crosstalk between different signaling pathways, pretreatment of HepG2 with N-acetylcysteine, an ROS scavenger, attenuated 4-methoxy-TEMPO-induced DNA damage, suppressed JNK activation, and diminished autophagy induction. Furthermore, inhibiting JNK activation by a JNK-specific inhibitor, SP600125, decreased DNA damage levels induced by 4-methoxy-TEMPO. These results suggest that multiple mechanisms including ROS generation, DNA damage, and MAPK activation contribute to 4-methoxy-TEMPO-induced toxicity.

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“…To explore further the possible mechanisms of DNA damage induced by dronedarone, we assessed the generation of reactive oxygen species (ROS), which has been Environmental and Molecular Mutagenesis. DOI 10.1002/em recognized as a prominent trigger of DNA damage (Evans and Cooke, 2004;Chen et al, 2017). No significant alternation of intracellular ROS level was observed in dronedarone treated cells as measured by H 2 DCFDA staining (data not shown).…”

Section: Dronedarone Downregulates the Expression Of Topoisomerase IImentioning

confidence: 89%

“…DOI 10.1002/em recognized as a prominent trigger of DNA damage (Evans and Cooke, 2004;Chen et al, 2017). DOI 10.1002/em recognized as a prominent trigger of DNA damage (Evans and Cooke, 2004;Chen et al, 2017).…”

Section: Dronedarone Downregulates the Expression Of Topoisomerase IImentioning

confidence: 99%

DNA damage‐induced apoptosis and mitogen‐activated protein kinase pathway contribute to the toxicity of dronedarone in hepatic cells

Chen

Ren

et al. 2018

Environ and Mol Mutagen

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Dronedarone, an antiarrhythmic drug, has been marketed as an alternative to amiodarone. The use of dronedarone has been associated with severe liver injury; however, the mechanisms remain unclear. In this study, the possible mechanisms of dronedarone induced liver toxicity were characterized in HepG2 cells. Dronedarone decreased cells viability and induced apoptosis and DNA damage in a concentration- and time-dependent manner. Pretreatment of the HepG2 cells with apoptosis inhibitors (caspase-3, -8, and -9) or the necrosis inhibitor (Necrox-5), partially, but significantly, reduced the release of lactate dehydrogenase. Dronedarone caused the release of cytochrome c from mitochondria to cytosol, a prominent feature of apoptosis. In addition, the activation of caspase-2 was involved in dronedarone induced DNA damage and the activation of JNK and p38 signaling pathways. Inhibition of JNK and p38 by specific inhibitors attenuated dronedarone-induced cell death, apoptosis, and DNA damage. Additionally, suppression of caspase-2 decreased the activities of JNK and p38. Dronedarone triggered DNA damage was regulated by downregulation of topoisomerase IIα at both transcriptional and post-transcriptional levels. Taken together, our data show that DNA damage, apoptosis, and the activation of JNK and p38 contribute to dronedarone-induced cytotoxicity. Environ. Mol. Mutagen. 59:278-289, 2018. © 2018 Wiley Periodicals, Inc.

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Activation of the Nrf2 signaling pathway in usnic acid-induced toxicity in HepG2 cells

Cited by 40 publications

References 59 publications

Endoplasmic reticulum stress and MAPK signaling pathway activation underlie leflunomide-induced toxicity in HepG2 Cells

Endoplasmic reticulum stress and MAPK signaling pathway activation underlie leflunomide-induced toxicity in HepG2 Cells

ROS generation and JNK activation contribute to 4-methoxy-TEMPO-induced cytotoxicity, autophagy, and DNA damage in HepG2 cells

DNA damage‐induced apoptosis and mitogen‐activated protein kinase pathway contribute to the toxicity of dronedarone in hepatic cells

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