Peptide-based urinary monitoring of fibrotic nonalcoholic steatohepatitis by mass-barcoded activity-based sensors.

Noninvasive detection of nonalcoholic steatohepatitis (NASH), the progressive form of nonalcoholic fatty liver disease, promises to improve patient screening, accelerate drug trials, and reduce health care costs. On the basis of protease dysregulation of the biological pathways of fibrotic NASH, we developed the Glympse Bio Test System (GBTS) for multiplexed quantification of liver protease activity. GBTS-NASH comprises a mixture of 19 mass-barcoded PEGylated peptides that is administered intravenously and senses liver protease activity by releasing mass-barcoded reporters into urine for analysis by mass spectrometry.

Haptoglobin 2 Allele is Associated With Histologic Response to Vitamin E in Subjects With Nonalcoholic Steatohepatitis.

Background: Haptoglobin (Hp) genotype has been linked to oxidative stress and cardiovascular outcomes in response to vitamin E (VitE) among patients with diabetes mellitus. Its effect on histologic response to VitE in nonalcoholic steatohepatitis (NASH) is unknown.

Goals: Our objective was to determine if Hp genotype associates with response to VitE in patients with NASH.

A diet-induced animal model of non-alcoholic fatty liver disease and hepatocellular cancer.

Background & Aims: The lack of a preclinical model of progressive non-alcoholic steatohepatitis (NASH) that recapitulates human disease is a barrier to therapeutic development.

Methods: A stable isogenic cross between C57BL/6J (B6) and 129S1/SvImJ (S129) mice were fed a high fat diet with ad libitum consumption of glucose and fructose in physiologically relevant concentrations and compared to mice fed a chow diet and also to both parent strains.

Results: Following initiation of the obesogenic diet, B6/129 mice developed obesity, insulin resistance, hypertriglyceridemia and increased LDL-cholesterol.

Molecular mechanisms of lipotoxicity and glucotoxicity in nonalcoholic fatty liver disease.

The exposure of hepatocytes to high concentrations of lipids and carbohydrates and the ensuing hepatocellular injury are termed lipotoxicity and glucotoxicity, respectively. A common denominator is metabolic derangement, especially in regards to intracellular energy homeostasis, which is brought on by glucose intolerance and insulin resistance in tissues. In this review, we highlight the lipids and carbohydrates that provoke hepatocyte injury and the mechanisms involved in lipotoxicity and glucotoxicity, including endoplasmic reticulum stress, oxidative stress and mitochondrial impairment.

KEAP the balance between life and death.

Hepatocyte apoptosis in association with oxidative stress represent key pathogenic factors involved in tumor development in patients with non-alcoholic fatty liver disease (NAFLD). In our recent study, we established that cellular degradation of Kelch-like ECH-associated protein 1 (KEAP1) through sequestrosome (SQSTM)1/p62-dependent autophagy activates c-Jun NH2 terminal kinase (JNK), upregulates expression of Bcl-2-interacting mediator (BIM) and p53 upregulated modulator of apoptosis (PUMA), and contributes to hepatocyte apoptosis induced by saturated free fatty acids. These findings raise the possibility that dysregulation of KEAP1 may contribute to liver cell death and tumorigenesis during chronic inflammatory liver disease.

Saturated free fatty acids induce cholangiocyte lipoapoptosis.

Unlabelled: Recent studies have identified a cholestatic variant of nonalcoholic fatty liver disease (NAFLD) with portal inflammation and ductular reaction. Based on reports of biliary damage, as well as increased circulating free fatty acids (FFAs) in NAFLD, we hypothesized the involvement of cholangiocyte lipoapoptosis as a mechanism of cellular injury. Here, we demonstrate that the saturated FFAs palmitate and stearate induced robust and rapid cell death in cholangiocytes.

Degradation of cIAPs contributes to hepatocyte lipoapoptosis.

Hepatocyte apoptosis is a hallmark of nonalcoholic steatohepatitis. We have previously observed that the saturated free fatty acids (FFAs) induce hepatocyte apoptosis in part via a death receptor 5 (DR5)-mediated signaling pathway. Cellular inhibitor of apoptosis protein 1 and 2 (cIAP-1 and cIAP-2) proteins are potent inhibitors of death receptor-mediated apoptosis.

A hedgehog survival pathway in 'undead' lipotoxic hepatocytes.

Background & Aims: Ballooned hepatocytes in non-alcoholic steatohepatitis (NASH) generate sonic hedgehog (SHH). This observation is consistent with a cellular phenotype in which the cell death program has been initiated but cannot be executed. Our aim was to determine whether ballooned hepatocytes have potentially disabled the cell death execution machinery, and if so, can their functional biology be modeled in vitro.

OSU-03012 suppresses GRP78/BiP expression that causes PERK-dependent increases in tumor cell killing.

We have further defined mechanism(s) by which the drug OSU-03012 (OSU) kills tumor cells. OSU lethality was suppressed by knock down of PERK and enhanced by knock down of ATF6 and IRE1α. OSU treatment suppressed expression of the chaperone, BiP/GRP78, and did so through reduced stability of the protein.

Myofibroblast-derived PDGF-BB promotes Hedgehog survival signaling in cholangiocarcinoma cells.

Unlabelled: Cholangiocarcinoma (CCA) cells paradoxically express the death ligand, tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) and, therefore, are dependent upon potent survival signals to circumvent TRAIL cytotoxicity. CCAs are also highly desmoplastic cancers with a tumor microenvironment rich in myofibroblasts (MFBs). Herein, we examine a role for MFB-derived CCA survival signals.

Mechanisms of lysophosphatidylcholine-induced hepatocyte lipoapoptosis.

Isolated hepatocytes undergo lipoapoptosis, a feature of hepatic lipotoxicity, on treatment with saturated free fatty acids (FFA) such as palmitate (PA). However, it is unknown if palmitate is directly toxic to hepatocytes or if its toxicity is indirect via the generation of lipid metabolites such as lysophosphatidylcholine (LPC). PA-mediated hepatocyte lipoapoptosis is associated with endoplasmic reticulum (ER) stress, c-Jun NH(2)-terminal kinase (JNK) activation, and a JNK-dependent upregulation of the potent proapoptotic BH3-only protein PUMA (p53 upregulated modulator of apoptosis).

Death receptor 5 signaling promotes hepatocyte lipoapoptosis.

Nonalcoholic steatohepatitis is characterized by hepatic steatosis, elevated levels of circulating free fatty acids (FFA), endoplasmic reticulum (ER) stress, and hepatocyte lipoapoptosis. Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) death receptor 5 (DR5) is significantly elevated in patients with nonalcoholic steatohepatitis, and steatotic hepatocytes demonstrate increased sensitivity to TRAIL-mediated cell death. Nonetheless, a role for TRAIL and/or DR5 in mediating lipoapoptotic pathways is unexplored.

A role for miR-296 in the regulation of lipoapoptosis by targeting PUMA.

Saturated free fatty acids (FFA) induce hepatocyte lipoapoptosis, a key mediator of liver injury in nonalcoholic fatty liver disease (NAFLD). Lipoapoptosis involves the upregulation of the BH3-only protein PUMA, a potent pro-apoptotic protein. Given that dysregulation of hepatic microRNA expression has been observed in NAFLD, we examined the role of miRNA in regulating PUMA expression during lipotoxicity.

Hedgehog inhibition promotes a switch from Type II to Type I cell death receptor signaling in cancer cells.

TRAIL is a promising therapeutic agent for human malignancies. TRAIL often requires mitochondrial dysfunction, referred to as the Type II death receptor pathway, to promote cytotoxicity. However, numerous malignant cells are TRAIL resistant due to inhibition of this mitochondrial pathway.

Glycogen synthase kinase-3 (GSK-3) inhibition attenuates hepatocyte lipoapoptosis.

Backgrounds & Aims: Saturated free fatty acids induce hepatocyte lipoapoptosis, a key pathologic feature of non-alcoholic steatohepatitis. The saturated free fatty acid palmitate induces hepatocyte lipoapoptosis via an endoplasmic reticulum stress pathway resulting in c-Jun-N-terminal (JNK) activation. Glycogen synthase kinase (GSK)-3 is a serine/threonine kinase which may also promote JNK activation.

Transcriptional suppression of mir-29b-1/mir-29a promoter by c-Myc, hedgehog, and NF-kappaB.

MicroRNAs regulate pathways contributing to oncogenesis, and thus the mechanisms causing dysregulation of microRNA expression in cancer are of significant interest. Mature mir-29b levels are decreased in malignant cells, and this alteration promotes the malignant phenotype, including apoptosis resistance. However, the mechanism responsible for mir-29b suppression is unknown.

CHOP and AP-1 cooperatively mediate PUMA expression during lipoapoptosis.

Endoplasmic reticulum (ER) stress-mediated apoptosis is a key feature of hepatocyte cytotoxicity by saturated free fatty acids (FFA). This lipoapoptosis is dependent, in part, on the transcriptional upregulation of the BH3-only protein PUMA (p53 upregulated modulator of apoptosis). Although the activator protein (AP)-1 complex facilitates PUMA expression by saturated FFA, the transcription factor CAAT/enhancer binding homologous protein (CHOP) is also induced by ER stress and promotes apoptosis.

Mechanisms and clinical implications of hepatocyte lipoapoptosis.

Nonalcoholic fatty liver disease (NAFLD) is characterized by insulin resistance, elevated serum levels of free fatty acids (FFAs) and fatty infiltration of the liver. Accumulation of triglycerides in the hepatocyte results from the uptake and esterification of circulating FFAs by the liver. Contrary to current theory, hepatic steatosis appears to be a detoxification process, as FFAs are directly cytotoxic for the hepatocyte and inhibition of triglyceride formation enhances FFAs toxicity.

JNK1-dependent PUMA expression contributes to hepatocyte lipoapoptosis.

Free fatty acids (FFA) induce hepatocyte lipoapoptosis by a c-Jun N-terminal kinase (JNK)-dependent mechanism. However, the cellular processes by which JNK engages the core apoptotic machinery during lipotoxicity, especially activation of BH3-only proteins, remain incompletely understood. Thus, our aim was to determine whether JNK mediates induction of BH3-only proteins during hepatocyte lipoapoptosis.

Additive effect of apicidin and doxorubicin in sulfatase 1 expressing hepatocellular carcinoma in vitro and in vivo.

Background/aims: There are limited chemotherapy options for hepatocellular carcinoma (HCC). The heparin-degrading endosulfatase SULF1 functions as a liver tumor suppressor. We investigated the effects of the histone deacetylase inhibitor apicidin in combination with doxorubicin in SULF1-expressing HCC cells in vitro and in SULF1-expressing xenografts in nude mice.

The JNK inhibitor SP600129 enhances apoptosis of HCC cells induced by the tumor suppressor WWOX.

Background/aims: The FRA16D fragile site gene WWOX is a tumor suppressor that participates in p53-mediated apoptosis. The c-jun N-terminal kinase JNK1 interacts with WWOX and inhibits apoptosis. We investigated the function of WWOX in human hepatocellular carcinoma (HCC) and the effect of JNK inhibition on WWOX-mediated apoptosis.