Anti-tumor Effect of Oleic Acid in Hepatocellular Carcinoma Cell Lines via Autophagy Reduction.

Oleic acid (OA) is a component of the olive oil. Beneficial health effects of olive oil are well-known, such as protection against liver steatosis and against some cancer types. In the present study, we focused on OA effects in hepatocellular carcinoma (HCC), investigating responses to OA treatment (50-300 µM) in HCC cell lines (Hep3B and Huh7.5) and in a healthy liver-derived human cell line (THLE-2). Upon OA administration higher lipid accumulation, perilipin-2 increase, and autophagy reduction were observed in HCC cells as compared to healthy cells. OA in the presence of 10% FBS significantly reduced viability of HCC cell lines at 300 µM through Alamar Blue staining evaluation, and reduced cyclin D1 expression in a dose-dependent manner while it was ineffective on healthy hepatocytes. Furthermore, OA increased cell death by about 30%, inducing apoptosis and necrosis in HCC cells but not in healthy hepatocytes at 300 µM dosage. Moreover, OA induced senescence in Hep3B, reduced P-ERK in both HCC cell lines and significantly inhibited the antiapoptotic proteins c-Flip and Bcl-2 in HCC cells but not in healthy hepatocytes. All these results led us to conclude that different cell death processes occur in these two HCC cell lines upon OA treatment. Furthermore, 300 µM OA significantly reduced the migration and invasion of both HCC cell lines, while it has no effects on healthy cells. Finally, we investigated autophagy role in OA-dependent effects by using the autophagy inducer torin-1. Combined OA/torin-1 treatment reduced lipid accumulation and cell death as compared to single OA treatment. We therefore concluded that OA effects in HCC cells lines are, at least, in part dependent on OA-induced autophagy reduction. In conclusion, we report for the first time an autophagy dependent relevant anti-cancer effect of OA in human hepatocellular carcinoma cell lines.

c-FLIP regulates autophagy by interacting with Beclin-1 and influencing its stability.

c-FLIP (cellular FLICE-like inhibitory protein) protein is mostly known as an apoptosis modulator. However, increasing data underline that c-FLIP plays multiple roles in cellular homoeostasis, influencing differently the same pathways depending on its expression level and isoform predominance. Few and controversial data are available regarding c-FLIP function in autophagy. Here we show that autophagic flux is less effective in c-FLIP-/- than in WT MEFs (mouse embryonic fibroblasts). Indeed, we show that the absence of c-FLIP compromises the expression levels of pivotal factors in the generation of autophagosomes. In line with the role of c-FLIP as a scaffold protein, we found that c-FLIPL interacts with Beclin-1 (BECN1: coiled-coil, moesin-like BCL2-interacting protein), which is required for autophagosome nucleation. By a combination of bioinformatics tools and biochemistry assays, we demonstrate that c-FLIPL interaction with Beclin-1 is important to prevent Beclin-1 ubiquitination and degradation through the proteasomal pathway. Taken together, our data describe a novel molecular mechanism through which c-FLIPL positively regulates autophagy, by enhancing Beclin-1 protein stability.

Metformin exerts anti-cancerogenic effects and reverses epithelial-to-mesenchymal transition trait in primary human intrahepatic cholangiocarcinoma cells.

Intrahepatic cholangiocarcinoma (iCCA) is a highly aggressive cancer with marked resistance to chemotherapeutics without therapies. The tumour microenvironment of iCCA is enriched of Cancer-Stem-Cells expressing Epithelial-to-Mesenchymal Transition (EMT) traits, being these features associated with aggressiveness and drug resistance. Treatment with the anti-diabetic drug Metformin, has been recently associated with reduced incidence of iCCA. We aimed to evaluate the anti-cancerogenic effects of Metformin in vitro and in vivo on primary cultures of human iCCA. Our results showed that Metformin inhibited cell proliferation and induced dose- and time-dependent apoptosis of iCCA. The migration and invasion of iCCA cells in an extracellular bio-matrix was also significantly reduced upon treatments. Metformin increased the AMPK and FOXO3 and induced phosphorylation of activating FOXO3 in iCCA cells. After 12 days of treatment, a marked decrease of mesenchymal and EMT genes and an increase of epithelial genes were observed. After 2 months of treatment, in order to simulate chronic administration, Cytokeratin-19 positive cells constituted the majority of cell cultures paralleled by decreased Vimentin protein expression. Subcutaneous injection of iCCA cells previously treated with Metformin, in Balb/c-nude mice failed to induce tumour development. In conclusion, Metformin reverts the mesenchymal and EMT traits in iCCA by activating AMPK-FOXO3 related pathways suggesting it might have therapeutic implications.

The Role of Autophagy in Liver Epithelial Cells and Its Impact on Systemic Homeostasis.

: Autophagy plays a role in several physiological and pathological processes as it controls the turnover rate of cellular components and influences cellular homeostasis. The liver plays a central role in controlling organisms' metabolism, regulating glucose storage, plasma proteins and bile synthesis and the removal of toxic substances. Liver functions are particularly sensitive to autophagy modulation. In this review we summarize studies investigating how autophagy influences the hepatic metabolism, focusing on fat accumulation and lipids turnover. We also describe how autophagy affects bile production and the scavenger function within the complex homeostasis of the liver. We underline the role of hepatic autophagy in counteracting the metabolic syndrome and the associated cardiovascular risk. Finally, we highlight recent reports demonstrating how the autophagy occurring within the liver may affect skeletal muscle homeostasis as well as different extrahepatic solid tumors, such as melanoma.