The liver is frequently challenged by surgery-induced metabolic overload, viruses or toxins, which induce the formation of reactive oxygen species. To determine the effect of oxidative stress on liver regeneration and to identify the underlying signaling pathways, we studied liver repair in mice lacking the Nrf2 transcription factor. In these animals, expression of several cytoprotective enzymes was reduced in hepatocytes, resulting in oxidative stress. After partial hepatectomy, liver regeneration was significantly delayed. Using in vitro and in vivo studies, we identified oxidative stress-mediated insulin/insulin-like growth factor resistance as an underlying mechanism. This deficiency impaired the activation of p38 mitogenactivated kinase, Akt kinase and downstream targets after hepatectomy, resulting in enhanced death and delayed proliferation of hepatocytes. Our results reveal novel roles of Nrf2 in the regulation of growth factor signaling and in tissue repair. In addition, they provide new insight into the mechanisms underlying oxidative stress-induced defects in liver regeneration. These findings may provide the basis for the development of new strategies to improve regeneration in patients with acute or chronic liver damage.

Many phase II protective genes contain a cis-acting enhancer region known as the antioxidant response element (ARE). Increased expression of these genes contributes to the protection of cells from oxidative stress. Transgenic reporter mice were created that carry in their genome the core ARE coupled to the human placental alkaline phosphatase (hPAP) reporter gene. Primary cortical cultures derived from these mice were treated with tBHQ resulting in a dose-dependent increase in hPAP activity. Histochemical staining for hPAP activity was observed in both glia and neurons from tBHQ-treated cultures. The tBHQ-mediated increase in hPAP was not affected by the antioxidant glutathione monoethyl ester (GSHEE), whereas the increase in hPAP following DEM treatment was completely blocked by GSHEE. Pre-treatment of cultures with the PI3-kinase inhibitor LY 294002 demonstrated a dose-dependent decrease in tBHQ-induced hPAP activity. In addition, the tBHQ-mediated expression of ARE-driven genes in primary cortical cultures was blocked by LY 294002. Interestingly, basal expression of Nrf2 was also inhibited by LY 294002. We theorize that increased levels of genes controlled by the ARE are important for cellular protection against oxidative stress. These ARE-hPAP transgenic mice will be an important in vivo model for testing our hypothesis.

The liver is frequently exposed to insults, including toxic chemicals and alcohol, viral infection or metabolic overload. Although it can fully regenerate after acute injury, chronic liver damage causes liver fibrosis and cirrhosis, which can result in complete liver failure. In this study, we demonstrate that the NF-E2-related factor 2 (Nrf2) transcription factor protects the liver from acute and chronic toxin-mediated damage. Repair of the liver injury that occurs after a single treatment with the hepatotoxin carbon tetrachloride (CCl 4 ) was severely delayed in Nrf2-deficient mice. The defect in repair was accompanied by an enhanced and prolonged inflammatory and profibrotic response. After long-term CCl 4 treatment, liver fibrosis was strongly aggravated in the Nrf2 knockout mice and inflammation was enhanced. We demonstrate that these abnormalities are at least in part due to the reduced expression of known and novel Nrf2 target genes in hepatocytes, which encode enzymes involved in the detoxification of CCl 4 and its metabolites. These results suggest that activation of Nrf2 may be a novel strategy to prevent or ameliorate toxin-induced liver injury and fibrosis.

Background The cisplatin-resistance is still a main course for chemotherapy failure of lung cancer patients. Cisplatin-resistant cancer cells own higher malignance and exhibited increased metastatic ability, but the mechanism is not clear. In this study, we investigated the effects of Ataxia Telangiectasia Mutated (ATM) on lung cancer metastasis. Materials and methods Cisplatin-resistant A549CisR and H157CisR cell line were generated by long-term treating parental A549 and H157 cells (A549P and H157P) with cisplatin. Cell growth, cell migration and cell invasion were determined. Gene expressions were determined by Western Blot and qPCR. Tumor metastasis was investigated using a xenograft mouse model. Results The IC50 of the cisplatin-resistant cells (A549CisR and H157CisR cells) to cisplatin was 6–8 higher than parental cells. The A549CisR and H157CisR cells expressed lower level of E-cadherin and higher levels of N-cadherin, Vimentin and Snail compared to the parental A549P and H157P cells, and exhibited stronger capabilities of metastatic potential compared to the parental cells. The ATM expression was upregulated in A549CisR and H157CisR cells and cisplatin treatment also upregulated expression of ATM in parental cells, The inhibition of ATM by using specific ATM inhibitor CP466722 or knock-down ATM by siRNA suppressed Epithelial-to-Mesenchymal transition (EMT) and metastatic potential of A549CisR and H157CisR cells. These data suggest that ATM mediates the cisplatin-resistance in lung cancer cells. Expressions of JAK 1,2, 、 STAT 3 、PD-L1 and ATM were increased in A549CisR and H157CisR cells and could by induced by cisplatin in parental lung cancer cells. Interestedly, ATM upregulated PD-L1 expression via JAK 1,2 /STAT 3 pathway and inhibition of ATM decreased JAK/STAT3 signaling and decreased PD-L1 expression. The treatment of PD-L1 neutralizing Ab reduced EMT and cell invasion. Inhibition of JAK 1,2 /STAT 3 signaling by specific inhibitors suppressed ATM-induced PD-L1 expression, EMT and cell invasion. Importantly, inhibition of ATM suppressed EMT and tumor metastasis in cisplatin-resistant lung cancer cells in an orthotopic xenograft mouse model. Conclusions Our results show that ATM regulates PD-L1 expression through activation of JAK/STAT3 signaling in cisplatin-resistant cells. Overexpression of ATM contributes to cisplatin-resistance in lung cancer cells. Inhibition of ATM reversed EMT and inhibited cell invasion and tumor metastasis. Thus, ATM may be a potential target for the treatment of cisplatin-resistant lung cancer. Electronic supplementary material The online version of this article (10.1186/s13046-019-1161-8) contains supplementary material, which is available to authorized users.