Sunitinib induced hepatotoxicity in L02 cells via ROS-MAPKs signaling pathway

In vitro assessment of the role of endoplasmic reticulum stress in sunitinib-induced liver and kidney toxicity

Sunitinib, a multi-targeted tyrosine kinase inhibitor, is prescribed for the treatment of metastatic gastrointestinal stromal tumors, advanced metastatic renal cell carcinoma, and pancreatic neuroendocrine tumors. Hepatotoxicity and nephrotoxicity are significant adverse effects of sunitinib administration; however, there is limited information regarding the molecular mechanisms of these adverse effects. The aim of the present study was to elucidate the role of endoplasmic reticulum stress in hepatotoxicity and nephrotoxicity induced by sunitinib. In addition to endoplasmic reticulum stress, oxidative stress and mitochondrial membrane potential were evaluated to investigate the molecular mechanism more comprehensively. Findings revealed that sunitinib exposure significantly increased the reactive oxygen species levels and decreased the Nrf2 gene expression and GSH/GSSG ratio, suggesting oxidative stress induction in normal hepatocyte (AML12) and normal kidney (HK-2) cell lines. Endoplasmic reticulum stress markers, including ATF4, CHOP, IRE1α, XBP1s and ATF6 mRNA expressions, were upregulated in AML12 cells. Furthermore, enhanced intracellular calcium levels also indicate endoplasmic reticulum stress in hepatocytes. In contrast, sunitinib exposure did not alter endoplasmic reticulum-related gene expression levels and intracellular calcium levels in HK-2 cells. In terms of mitochondrial membrane potential and caspase-3 activity, sunitinib induced mitochondrial membrane damage and increased caspase-3 activation not only in AML12 cells but also in HK-2 cells. The research findings indicate that sunitinib may induce cytotoxic effects in hepatocytes through mechanisms involving oxidative stress, endoplasmic reticulum stress, and mitochondrial damage. However, in the kidney, the toxicity mechanism is different from that of liver, and the endoplasmic reticulum stress does not seem to be involved in this mechanism.

Gut microbiota depletion and FXR inhibition exacerbates zonal hepatotoxicity of sunitinib

Rationale: Sunitinib is a small-molecule tyrosine kinase inhibitor associated with the side-effect of liver injury. The impaired cell type in liver and the hepatotoxicity mechanisms is still unclear. Methods: Spatial metabolomics, transmission electron microscopy, immunofluorescence co-staining, and isolation of bile duct cells and liver sinusoidal endothelial cells (LSECs) were used to evaluate the zonated hepatotoxicity of sunitinib. Farnesoid X receptor (FXR) conditional knockout mice, metagenomics analysis, bacteria clearance, bacterial culture, Parabacteroides distasonis and 3-oxolithocholic acid supplementation were used to evaluate the hepatotoxicity mechanisms of sunitinib. Results: Phenotype analysis found that hepatic autophagy, apoptosis, and mitochondrial injury were observed in vivo or in vitro after sunitinib treatment. By using spatial metabolomics and isolation of bile duct cells and LSECs, the zonated drug toxicity was observed around the portal vein. Hepatocytes, bile duct cells, and LSECs were damaged after sunitinib treatment. FXR inhibition and gut microbiota depletion aggravated sunitinib-induced liver injury. For diurnal variation, sunitinib-induced liver injury was enhanced at night compared with that at day, and FXR and gut microbiota participated in circadian rhythmic hepatotoxicity induced by sunitinib. Conclusions: Our data suggested activation of FXR and Parabacteroides distasonis supplementation may be used to improve sunitinib-induced hepatotoxicity.

Bi-directional regulation of type I interferon signaling by heme oxygenase-1

Moderate activation of IFN-I contributes to the body's immune response, but its abnormal expression, stimulated by oxidative stress or other factors causes pathological damage. Heme oxygenase-1 (HO-1), induced by stress stimuli in the body, exerts a central role in cellular protection. Here we showed that HO-1 could promote IFN-1 under Spring Viremia of Carp virus (SVCV) infection and concomitantly attenuate the replication of SVCV. Further characterization of truncated mutants of HO-1 confirmed that intact HO-1 was essential for its antiviral function via IFN-I. Importantly, HO-1 inhibited the IFN-I signal by degrading the IRF3/7 through the autophagy pathway when it was triggered by H2O2 treatment. The iron ion-binding site (His28) was critical for HO-1 to degrade IRF3/7. HO-1 degradation of IRF3/7 is conserved in fish and mammals. Collectively, HO-1 regulates IFN-I positively under viral infection and negatively under oxidative stress, elucidating a mechanism by which HO-1 regulates IFN-I signaling in bi-directions.