Propofol but not sevoflurane prevents mitochondrial dysfunction and oxidative stress by limiting HIF-1α activation in hepatic ischemia/reperfusion injury.

Mitochondrial dysfunction, reactive oxygen species (ROS) production and oxidative stress during reperfusion are determinant in hepatic ischemia/reperfusion (I/R) injury but may be impacted by different anesthetic agents. Thus, we aimed at comparing the effects of inhaled sevoflurane or intravenous propofol anesthesia on liver mitochondria in a rodent model of hepatic I/R injury. To this, male Wistar rats underwent I/R surgery using sevoflurane or propofol. In the I/R model, propofol limited the raise in serum aminotransferase levels as compared to sevoflurane. Mitochondrial oxygen uptake, respiratory activity, membrane potential and proton leak were altered in I/R; however, this impairment was significantly prevented by propofol but not sevoflurane. In addition, differently from sevoflurane, propofol limited hepatic I/R-induced mitochondria H2O2 production rate, free radical leak and hydroxynonenal-protein adducts levels. The I/R group anesthetized with propofol also showed a better recovery of hepatic ATP homeostasis and conserved integrity of mitochondrial PTP. Moreover, hypoxia-inducible factor 1 alpha (HIF-1α) expression was limited in such group. By using a cell model of desferoxamine-dependent HIF activation, we demonstrated that propofol was able to inhibit apoptosis and mitochondrial depolarization associated to HIF-1α action. In conclusion, hepatic I/R injury induces mitochondrial dysfunction that is not prevented by inhaled sevoflurane. On the contrary, propofol reduces liver damage and mitochondrial dysfunction by preserving respiratory activity, membrane potential and energy homeostasis, and limiting free radicals production as well as PTP opening. These hepatoprotective effects may involve the inhibition of HIF-1α.

Mitochondrial Signaling and Hepatocellular Carcinoma: Molecular Mechanisms and Therapeutic Implications.

BACKGROUND: Molecular pathogenesis of hepatocellular carcinoma is complex and implies a multistep process involving different genetic and epigenetic alterations, as well as altered molecular pathways. Among these features, oxidative stress and mitochondria dysfunction represent an important trigger to hepatocarcinogenesis regardless of underlying liver disease etiology. An important part of the actual cancer research is focused on the molecular mechanisms and the signaling pathways involved in the process of so called "mitochondrial malignancy". METHOD: Aim of this review is to summarize the main molecular mechanisms and the pathological consequences of oxidative stress and mitochondrial dysfunction in liver cancer. Furthermore, an up-to-date insight in therapeutic implications of the aforementioned processes is consistently developed. A literature search was conducted using PubMed until October 2015, based on English language journals. RESULTS: Mitochondrial dysfunction may dramatically alter cell growth and proliferation by means of several "retrograde" mitochondria-nucleus signaling pathways, all of which have been shown to play a significant role in hepatocarcinogenesis. Nuclear oncogenes and tumor suppressors alike regulate mitochondrial turnover and function in a thick cross-talk whose role is fundamental in human oncology. CONCLUSION: The current knowledge on the role of mitochondrial signaling and oxidative stress in hepatocarcinogenesis seems to support the use of antioxidant agents in hepatocarcinoma patients, for instance in the adjuvant setting after radical treatments where their favorable cost-effective and safety profile may enable long-terms therapies aimed at preventing tumor recurrence. Data from randomized-controlled trials are warranted in order to confirm these promising results.

Oxysterols induce mitochondrial impairment and hepatocellular toxicity in non-alcoholic fatty liver disease.

Non-alcoholic fatty liver disease (NAFLD) is a chronic hepatic disorder affecting up to 25% of the general population. Several intracellular events leading to NAFLD and progression to non-alcoholic steatohepatitis (NASH) have been identified, including lipid accumulation, mitochondrial dysfunction and oxidative stress. Emerging evidence links both hepatic free fatty acids (FFAs) and cholesterol (FC) accumulation in NAFLD development; in particular oxysterols, the oxidative products of cholesterol, may contribute to liver injury. We performed a targeted lipidomic analysis of oxysterols in the liver of male Wistar rats fed a high-fat (HF), high-cholesterol (HC) or high-fat/high-cholesterol (HF/HC) diet. Both HF and HC diets caused liver steatosis, but the HF/HC diet resulted in steatohepatitis with associated mitochondrial dysfunction. Above all, the oxysterol cholestane-3beta,5alpha,6beta-triol (triol) was particularly increased in the liver of rats fed diets rich in cholesterol. To verify the molecular mechanism involved in mitochondrial dysfunction and hepatocellular toxicity, Huh7 and primary rat hepatocytes were exposed to palmitic acid (PA) and/or oleic acid (OA), with or without triol. This compound induced apoptosis in cells co-exposed to both PA and OA, and this was associated with impaired mitochondrial respiration as well as down-regulation of PGC1-alpha, mTFA and NRF1.In conclusion, our data show that hepatic free fatty acid or oxysterols accumulation per se induce low hepatocellular toxicity. On the contrary, hepatic accumulation of both fatty acids and toxic oxysterols such as triol are determinant in the impairment of mitochondrial function and biogenesis, contributing to liver pathology in NAFLD.