BaCKgRoUND aND aIMS: Despite the availability of new-generation drugs, hepatocellular carcinoma (HCC) is still the third most frequent cause of cancer-related deaths worldwide. Cerium oxide nanoparticles (CeO 2 NPs) have emerged as an antioxidant agent in experimental liver disease because of their antioxidant, anti-inflammatory, and antisteatotic properties. In the present study, we aimed to elucidate the potential of CeO 2 NPs as therapeutic agents in HCC. appRoaCH aND ReSUltS: HCC was induced in 110 Wistar rats by intraperitoneal administration of diethylnitrosamine for 16 weeks. Animals were treated with vehicle or CeO 2 NPs at weeks 16 and 17. At the eighteenth week, nanoceria biodistribution was assessed by mass spectrometry (MS). The effect of CeO 2 NPs on tumor progression and animal survival was investigated. Hepatic tissue MS-based phosphoproteomics as well as analysis of principal lipid components were performed. The intracellular uptake of CeO 2 NPs by human ex vivo perfused livers and human hepatocytes was analyzed. Nanoceria was mainly accumulated in the liver, where it reduced macrophage infiltration and inflammatory gene expression. Nanoceria treatment increased liver apoptotic activity, while proliferation was attenuated. Phosphoproteomic analysis revealed that CeO 2 NPs affected the phosphorylation of proteins mainly related to cell adhesion and RNA splicing. CeO 2 NPs decreased phosphatidylcholine-derived arachidonic acid and reverted the HCC-induced increase of linoleic acid in several lipid components. Furthermore, CeO 2 NPs reduced serum alpha-protein levels and improved the survival of HCC rats. Nanoceria uptake by ex vivo perfused human livers and in vitro human hepatocytes was also demonstrated. CoNClUSIoNS: These data indicate that CeO 2 NPs partially revert the cellular mechanisms involved in tumor progression and significantly increase survival in HCC rats, suggesting that they could be effective in patients with HCC.

Oxidative stress induced by the overproduction of free radicals or reactive oxygen species (ROS) has been considered as a key pathogenic mechanism contributing to the initiation and progression of injury in liver diseases. Consequently, during the last few years antioxidant substances, such as superoxide dismutase (SOD), resveratrol, colchicine, eugenol, and vitamins E and C have received increasing interest as potential therapeutic agents in chronic liver diseases. These substances have demonstrated their efficacy in equilibrating hepatic ROS metabolism and thereby improving liver functionality. However, many of these agents have not successfully passed the scrutiny of clinical trials for the prevention and treatment of various diseases, mainly due to their unspecificity and consequent uncontrolled side effects, since a minimal level of ROS is needed for normal functioning. Recently, cerium oxide nanoparticles (CeO2NPs) have emerged as a new powerful antioxidant agent with therapeutic properties in experimental liver disease. CeO2NPs have been reported to act as a ROS and reactive nitrogen species (RNS) scavenger and to have multi-enzyme mimetic activity, including SOD activity (deprotionation of superoxide anion into oxygen and hydrogen peroxide), catalase activity (conversion of hydrogen peroxide into oxygen and water), and peroxidase activity (reducing hydrogen peroxide into hydroxyl radicals). Consequently, the beneficial effects of CeO2NPs treatment have been reported in many different medical fields other than hepatology, including neurology, ophthalmology, cardiology, and oncology. Unlike other antioxidants, CeO2NPs are only active at pathogenic levels of ROS, being inert and innocuous in healthy cells. In the current article, we review the potential of CeO2NPs in several experimental models of liver disease and their safety as a therapeutic agent in humans as well.

Non-alcoholic fatty liver disease (NAFLD) is the most common cause of chronic liver disease worldwide, ranging from steatosis to non-alcoholic steatohepatitis (NASH). Recently, cerium oxide nanoparticles (CeO 2 NPs) have emerged as a new antioxidant agent with hepatoprotective properties in experimental liver disease. The aim of the current investigation was to elucidate whether CeO 2 NPs display beneficial effects in an experimental model of NAFLD.Therefore, fifteen Wistar rats were subjected to a methionine and choline deficient diet (MCDD) for 6 weeks and intravenously treated with CeO 2 NP or vehicle during the weeks three and four of the diet. The effect of CeO 2 NPs on serum biochemistry, hepatic steatosis, inflammation, fatty acid content and expression of reactive oxygen species (ROS) and lipid metabolism related genes was assessed. MCDD fed rats showed increased inflammation, enhanced hepatic lipid accumulation of both saturated and unsaturated fatty acids (FAs) and overexpression of genes related to fatty liver and ROS metabolism. Treatment with CeO 2 NPs was able to reduce the size and content of hepatocyte lipid droplets, the hepatic concentration of triglyceride- and cholesterol ester-derived FAs and the expression of several genes involved in cytokine, adipokine and chemokine signaling pathways. These findings suggest that CeO 2 NPs could be of beneficial value in NAFLD.