UNASSIGNED: Autophagy is a process that allows the degradation of detrimental components through the lysosome to maintain cellular homeostasis under variable stimuli. SQSTM1 is a key molecule involved in functional autophagy and is linked to different signaling pathways, oxidative responses, and inflammation. Dysregulation of autophagy is reported in a broad spectrum of diseases. Accumulation of SQSTM1 reflects impaired autophagy, which is related to carcinogenesis and progression of various tumors, including hepatocellular carcinoma (HCC). This study investigated SQSTM1 protein expression in HCC and its relation to the clinicopathological features and the likelihood of tumor recurrence after radiofrequency ablation (RFA).
UNASSIGNED: This study included 50 patients with cirrhotic HCC of Barcelona Clinic Liver Cancer stages 0/A-B eligible for RFA. Tumor and peritumor biopsies were obtained just prior to local ablation and assessed for tumor pathological grade and SQSTM1 expression by immunohistochemistry. Patients were followed for one year after achieving complete ablation to detect any tumor recurrence.
UNASSIGNED: Serum alpha-fetoprotein level (U = 149.50, P = 0.027∗) and pathological grade of the tumor (χ2 = 12.702, P = 0.002∗) associated significantly with the tumor response to RFA. SQSTM1 expression level was significantly increased in HCC compared to the adjacent peritumor cirrhotic liver tissues (Z = 5.927, P < 0.001∗). Significant direct relation was found between SQSTM1 expression level in HCC and the pathological grade of the tumor (H = 33.789, P < 0.001∗). On follow-up, tumor and peritumor SQSTM1 expression levels performed significantly as a potential predictor of the overall survival, but not the disease recurrence.
UNASSIGNED: SQSTM1 expression could determine aggressive HCC, even with reasonable tumor size and number, and identify the subset of HCC patients with short overall survival and unfavorable prognosis. SQSTM1 expression could not predict post-RFA intrahepatic HCC recurrence. SQSTM1 may be a potential biomarker and target for the selection of HCC patients for future therapies.

Acetaminophen (APAP) is a widely used analgesic and antipyretic drug, which is safe at therapeutic doses but can cause severe liver injury and even liver failure after overdoses. The mouse model of APAP hepatotoxicity recapitulates closely the human pathophysiology. As a result, this clinically relevant model is frequently used to study mechanisms of drug-induced liver injury and even more so to test potential therapeutic interventions. However, the complexity of the model requires a thorough understanding of the pathophysiology to obtain valid results and mechanistic information that is translatable to the clinic. However, many studies using this model are flawed, which jeopardizes the scientific and clinical relevance. The purpose of this review is to provide a framework of the model where mechanistically sound and clinically relevant data can be obtained. The discussion provides insight into the injury mechanisms and how to study it including the critical roles of drug metabolism, mitochondrial dysfunction, necrotic cell death, autophagy and the sterile inflammatory response. In addition, the most frequently made mistakes when using this model are discussed. Thus, considering these recommendations when studying APAP hepatotoxicity will facilitate the discovery of more clinically relevant interventions.

Acetaminophen (APAP) overdose is the leading cause of drug-induced liver injury, and its prognosis depends on the balance between hepatocyte death and regeneration. Sirtuin 6 (SIRT6) has been reported to protect against oxidative stress-associated DNA damage. But whether SIRT6 regulates APAP-induced hepatotoxicity remains unclear. In this study, the protein expression of nuclear and total SIRT6 was up-regulated in mice liver at 6 and 48 h following APAP treatment, respectively. Sirt6 knockdown in AML12 cells aggravated APAP-induced hepatocyte death and oxidative stress, inhibited cell viability and proliferation, and downregulated CCNA1, CCND1 and CKD4 protein levels. Sirt6 knockdown significantly prevented APAP-induced NRF2 activation, reduced the transcriptional activities of GSTμ and NQO1 and the mRNA levels of Nrf2, Ho-1, Gstα and Gstμ. Furthermore, SIRT6 showed potential protein interaction with NRF2 as evidenced by co-immunoprecipitation (Co-IP) assay. Additionally, the protective effect of P53 against APAP-induced hepatocytes injury was Sirt6-dependent. The Sirt6 mRNA was significantly down-regulated in P53 -/- mice. P53 activated the transcriptional activity of SIRT6 and exerted interaction with SIRT6. Our results demonstrate that SIRT6 protects against APAP hepatotoxicity through alleviating oxidative stress and promoting hepatocyte proliferation, and provide new insights in the function of SIRT6 as a crucial docking molecule linking P53 and NRF2.

Gallic acid (GA) is a known phenolic compound with anti-inflammatory, antioxidant, and anti-cancer activities. The objective of this research is to evaluate the preventive role of GA against carbon tetrachloride (CCl4) induced liver fibrosis. Thirty-five (35) male Wistar rats were used in this study and were equally distributed into five groups (7 rats each). All groups were acclimatized for a week, Group I (control) rats were administered distilled water only. Group II rats were induced with a single dose of CCl4 (1.25 mL/kg in olive oil (1:1); IP) to cause hepatic damage, while Groups III, IV, and V, rats were intoxicated with CCl4. After 24 h the rats in groups III, IV, and V were given 50 mg/kg of silymarin, 50 mg/kg of GA, and 100 mg/kg of GA daily for one week respectively. Rats were sacrificed and fasting blood was estimated for biochemical analysis while the liver was excised for molecular studies. Results from this study revealed that GA significantly decreases serum hepatic enzymes, down-regulate the expression of pro-inflammatory cytokines, interleukin 1 beta (IL-1B), interleukin 6 (IL-6), cyclooxygenase 2 (COX 2), and tumor necrosis factor-alpha (TNF α), and up-regulate antioxidant gene expression (superoxide dismutase and catalase). The use of gallic acid as natural antioxidants can be promising in ameliorating liver diseases.

BACKGROUND: The therapeutic utility of the effective chemotherapeutic agent cisplatin is hampered by its nephrotoxic effect. We aimed from the current study to examine the possible protective effects of amlodipine through gamma-glutamyl transpeptidase (GGT) enzyme inhibition against cisplatin nephrotoxicity.
METHODS: Amlodipine (5 mg/kg, po) was administered to rats for 14 successive days. On the 10th day, nephrotoxicity was induced by a single dose of cisplatin (6.5 mg/kg, ip). On the last day, blood samples were collected for estimation of kidney function, while kidney samples were used for determination of GGT activity, oxidative stress, inflammatory, and apoptotic markers, along with histopathological evaluation.
RESULTS: Amlodipine alleviated renal injury that was manifested by significantly diminished serum creatinine and blood urea nitrogen levels, compared to cisplatin group. Amlodipine inhibited GGT enzyme, which participates in the metabolism of extracellular glutathione (GSH) and platinum-GSH-conjugates to a reactive toxic thiol. Besides, amlodipine diminished mRNA expression of NADPH oxidase in the kidney, while enhanced the anti-oxidant defense by activating Nrf2/HO-1 signaling. Additionally, it showed marked anti-inflammatory response by reducing expressions of p38 mitogen-activated protein kinase (p38 MAPK) and nuclear factor-kappa B (NF-κB), with subsequent down-regulation of tumor necrosis factor-alpha (TNF-α), interleukin-6 (IL-6), and vascular cell adhesion molecule-1 (VCAM-1). Moreover, amlodipine reduced Bax/Bcl-2 ratio and elevated hepatocyte growth factor (HGF), thus favoring renal cell survival.
CONCLUSIONS: Effective GGT inhibition by amlodipine associated with enhancement of anti-oxidant defense and suppression of inflammatory signaling and apoptosis support our suggestion that amlodipine could replace toxic GGT inhibitors in protection against cisplatin nephrotoxicity.

4-Nitrophenol (PNP), is generally regarded as an environmental endocrine disruptor (EED). Phytosterin (PS), a new feed additive, possesses highly efficient antioxidant activities. The transcription factor, nuclear factor-erythroid 2-related factor 2 (Nrf2), is an important regulator of cellular oxidative stress. Using rats, this study examined PNP-induced testicular oxidative damage and PS-mediated protection against that damage. The generation of MDA and H2O2 upon PNP and PS treatment was milder than that upon treatment with PNP alone. This mitigation was accompanied by partially reversed changes in SOD, CAT, GSH and GSH-Px. Moreover, PNP significantly reduced the caudal epididymal sperm counts and serum testosterone levels. Typical morphological changes were also observed in the testes of PNP-treated animals. PNP reduced the transcriptional level of Nrf2, as evaluated by RT-PCR, but it promoted the dissociation from the Nrf2 complex, stabilization and translocation into the nucleus, as evaluated by immunohistochemistry and Western blotting. In addition, PNP enhanced the Nrf2-dependent gene expression of heme oxygenase-1 (HO-1) and glutamate-cysteine ligase catalytic subunit (GCLC). These results suggest that the Nrf2 pathway plays an important role in PNP-induced oxidative damage and that PS possesses modulatory effects on PNP-induced oxidative damage in rat testes.

Hepatocellular carcinoma (HCC) is the third most frequent cause of cancer deaths throughout the world. This study was aimed to analyze oxidative stress and cell damage in a multistage model of liver carcinogenesis induced by diethylnitrosamine (DEN) in rats. Male Wistar rats weighing 145-150 g were divided into three groups: control, precancerous lesions (PL) (which received 100 mg DEN once a week every 6 weeks up to 28 weeks), and advanced HCC (50 mg DEN once/twice per week up to 19 weeks). Lipid peroxidation (TBARS), superoxide dismutase (SOD) activity, and expression of transforming growth factor-1 beta (TGF)-1β, endothelial and inducible nitric oxide syntahese (eNOS, iNOS), NADPH quinone oxireductase (NQO)-1, nuclear factor erythroid 2-related factor (NrF)2, kelch-like ECH-associated protein (Keap)1 and heat shock protein (HSP)70 were measured. TBARS concentration was augmented in the PL and advanced HCC groups. SOD activity, TGF-1β and Nrf2 expression were higher in animals with precancerous lesions. In advanced HCC, expression of NQO1 and iNOS increased while there was a decrease in HPS70 expression. Data obtained provide evidence for the differential activation of proteins involved in oxidative stress and cell damage during progression of carcinogenesis in an animal model of HCC.

The aim of the present study was to investigate the effects of livestock feed supplemented with grape pomace (GP) or olive oil mill wastewater (OMW) byproducts on the enzymatic activity and protein expression of antioxidants enzymes, in liver and spleen tissue of sheep. Thus, 36 male sheep of Chios breed were divided into 3 homogeneous groups, control group (n = 12), GP group (n = 12) and OMW group (n = 12), receiving standard or experimental feed. Liver and spleen tissues were collected at 42 and 70 days post-birth. The enzymatic activity of superoxide dismutase (SOD) and glutathione-s-transferase (GST) and also the protein expression of γ-synthase glutamyl custeine (γ-GCS) were determined in these tissues. The results showed GP group exhibited increased enzymatic activity of GST and protein expression of γ-GCS in liver compared to control group. In GP group\'s spleen, GST activity was increased compared to control but γ-GCS expression was not affected. In OMW group\'s liver, GST activity was increased and γ-GCS expression was reduced compared to control. In OMW group\'s spleen, GST activity was increased but GCS expression was not affected. SOD activity was not affected in both tissues either in GP or OMW group.

The Keap1-Nrf2-ARE pathway is an important antioxidant defense mechanism that protects cells from oxidative stress and the Keap1-Nrf2 protein-protein interaction (PPI) has become an important drug target to upregulate the expression of ARE-controlled cytoprotective oxidative stress response enzymes in the development of therapeutic and preventive agents for a number of diseases and conditions. However, most known Nrf2 activators/ARE inducers are indirect inhibitors of Keap1-Nrf2 PPI and they are electrophilic species that act by modifying the sulfhydryl groups of Keap1׳s cysteine residues. The electrophilicity of these indirect inhibitors may cause \"off-target\" side effects by reacting with cysteine residues of other important cellular proteins. Efforts have recently been focused on the development of direct inhibitors of Keap1-Nrf2 PPI. This article reviews these recent research efforts including the development of high throughput screening assays, the discovery of peptide and small molecule direct inhibitors, and the biophysical characterization of the binding of these inhibitors to the target Keap1 Kelch domain protein. These non-covalent direct inhibitors of Keap1-Nrf2 PPI could potentially be developed into effective therapeutic or preventive agents for a variety of diseases and conditions.

Keap1 protein acts as a cellular sensor for oxidative stresses and regulates the transcription level of antioxidant genes through the ubiquitination of a corresponding transcription factor, Nrf2. A small molecule capable of binding to the Nrf2 interaction site of Keap1 could be a useful medicine. Here, we report two crystal structures, referred to as the soaking and the cocrystallization forms, of the Kelch domain of Keap1 with a small molecule, Ligand1. In these two forms, the Ligand1 molecule occupied the binding site of Keap1 so as to mimic the ETGE motif of Nrf2, although the mode of binding differed in the two forms. Because the Ligand1 molecule mediated the crystal packing in both the forms, the influence of crystal packing on the ligand binding was examined using a molecular dynamics (MD) simulation in aqueous conditions. In the MD structures from the soaking form, the ligand remained bound to Keap1 for over 20 ns, whereas the ligand tended to dissociate in the cocrystallization form. The MD structures could be classified into a few clusters that were related to but distinct from the crystal structures, indicating that the binding modes observed in crystals might be atypical of those in solution. However, the dominant ligand recognition residues in the crystal structures were commonly used in the MD structures to anchor the ligand. Therefore, the present structural information together with the MD simulation will be a useful basis for pharmaceutical drug development.