GDF11 restricts aberrant lipogenesis and changes in mitochondrial structure and function in human hepatocellular carcinoma cells.

Growth differentiation factor 11 (GDF11) has been characterized as a key regulator of differentiation in cells that retain stemness features. Recently, it has been reported that GDF11 exerts tumor-suppressive properties in hepatocellular carcinoma cells, decreasing clonogenicity, proliferation, spheroid formation, and cellular function, all associated with a decrement in stemness features, resulting in mesenchymal to epithelial transition and loss of aggressiveness. The aim of the present work was to investigate the mechanism associated with the tumor-suppressive properties displayed by GDF11 in liver cancer cells. Hepatocellular carcinoma-derived cell lines were exposed to GDF11 (50 ng/ml), RNA-seq analysis in Huh7 cell line revealed that GDF11 exerted profound transcriptomic impact, which involved regulation of cholesterol metabolic process, steroid metabolic process as well as key signaling pathways, resembling endoplasmic reticulum-related functions. Cholesterol and triglycerides determination in Huh7 and Hep3B cells treated with GDF11 exhibited a significant decrement in the content of these lipids. The mTOR signaling pathway was downregulated, and this was associated with a reduction in key proteins involved in the mevalonate pathway. In addition, real-time metabolism assessed by Seahorse technology showed abridged glycolysis as well as glycolytic capacity, closely related to an impaired oxygen consumption rate and decrement in adenosine triphosphate production. Finally, transmission electron microscopy revealed mitochondrial abnormalities, such as cristae disarrangement, consistent with metabolic changes. Results provide evidence that GDF11 impairs cancer cell metabolism targeting lipid homeostasis, glycolysis, and mitochondria function and morphology.

Differential modulation of interleukin 8 by interleukin 4 and interleukin 10 in HepG2 cells treated with acetaldehyde.

BACKGROUND/AIM: Pro-inflammatory cytokines and chemokines, such as interleukin (IL) 8, are important mediators of hepatic injury and repair following an insult. The purpose of this work was to study the regulation of IL-8 by IL-10 and IL-4 in HepG2 cells treated with acetaldehyde (Ac). METHODS: HepG2 cells were pretreated with IL-10 or IL-4 before exposure to Ac, examining IL-8 expression by reverse transcription polymerase chain reaction and Western blot. RESULTS: Ac treatment produced an increment in IL-8 induction and secretion that was prevented by IL-4 pretreatment, while IL-10 pretreatment failed to decrease Ac-induced IL-8 production. Consistent with these findings Ac increased NF-kappa B and AP-1 activation that were prevented by IL-4 but not by IL-10, findings accompanied by greater I kappa B-alpha levels in IL-4 but not IL-10 pretreated cells. In contrast to the pro-inflammatory role of IL-10 in HepG2, IL-10 did not show any change in the activation of NF-kappa B by Ac in WRL-68 cells, a human fetal hepatic cell line. Moreover, IL-10 did not induce the degradation of I kappa B-alpha in cellular extract from rat primary cultured cells. CONCLUSIONS: While the present findings demonstrate the anti-inflammatory role of IL-4 in preventing the expression of IL-8 by Ac, the regulation of chemokines by anti-inflammatory cytokines is complex and depends on the cellular lineage.

Alcohol-induced liver disease: when fat and oxidative stress meet.

Reactive oxygen species (ROS) act as signaling intermediates regulating multiple cellular processes. The fate and disposal of the signaling species are determined by the actions of antioxidants, particularly glutathione (GSH). The mitochondrial pool of GSH (mGSH) arises from the transport of cytosol GSH by a specific mitochondrial carrier and is responsible for the maintenance of a healthy competent organelle. The depletion of mGSH upon impairment of the mitochondrial transport activity leaves mitochondria unprotected from damaging effects of ROS overgeneration within the mitochondrial electron transport chain. Tumor necrosis factor-alpha (TNF-alpha) has emerged as a key player in the progression of the alcohol-induced liver disease (ALD), and is known to target mitochondria. Key components of TNF signaling include sphingolipids, particularly ceramide generated from acidic sphingomyelinase activation serving as a source for gangliosides. In experimental models alcohol consumption enhances cholesterol levels and subsequent deposition into mitochondria resulting in selective decrease in the mGSH stores which is sufficient by itself to sensitize hepatocytes to TNF-alpha-mediated cell death. Thus, the combination of TNF-alpha overproduction, enhanced glycosphingolipid generation and selective mGSH depletion by alcohol intake cooperate making the liver sensitive to alcohol.

Alcohol-induced liver disease: from molecular damage to treatment.

Although the interaction between alcohol and the liver has been the subject of intensive investigation since many years, several uncertainties remain to be solved. Good examples of what we need to learn are: The real number of patients with alcohol-induced liver disease (AILD), the dose of alcohol "safe" for the liver, the genetic predisposition to the damage or, on the other side of the coin, protecting from the damage. Rather recently, however, part of these questions started to be clarified, thus permitting a better definition of the role of each of these factors in AILD. In parallel to the clinical approach to AILD, the unveiling of the molecular and biochemical mechanisms involved in AILD has progressed and proved to be important in both a better understanding of the disease and, more important, in a more rational treatment of these disorders. This review will focus on what we currently know of AILD in clinical, biochemical and molecular terms and what we need to address in the future.

Alcohol induced liver disease: from molecular damage to treatment

Although the interaction between alcohol and the liver has been the subject of intensive investigation since many years, several uncertainties remain to be solved. Good examples of what we need to learn are: The real number of patients with alcohol-induced liver disease (AILD), the dose of alcohol "safe" for the liver, the genetic predisposition to the damage or, on the other side of the coin, protecting from the damage. Rather recently, however, part of these questions started to be clarified, thus permitting a better definition of the role of each of these factors in AILD. In parallel to the clinical approach to AILD, the unveiling of the molecular and biochemical mechanisms involved in AILD has progressed and proved to be important in both a better understanding of the disease and, more important, in a more rational treatment of these disorders. This review will focus on what we currently know of AILD in clinical, biochemical and molecular terms and what we need to address in the future