The Translational Bridge between Inflammation and Hepatocarcinogenesis.

Viral infections or persistent alcohol or drug abuse, together with intrinsic factors, lead to hepatitis, which often ends in the development of liver cirrhosis or hepatocellular carcinoma (HCC). With this review, we describe inflammatory liver diseases, such as acute liver failure, virus-induced hepatitis, alcoholic- and non-alcoholic steatohepatitis, and autoimmune hepatitis, and highlight their driving mechanisms. These include external factors such as alcohol misuse, viral infection and supernutrition, as well as intrinsic parameters such as genetic disposition and failure, in immune tolerance. Additionally, we describe what is known about the translational machinery within all these diseases. Distinct eukaryotic translation initiation factors (eIFs) with specific functional roles and aberrant expression in HCC are reported. Many alterations to the translational machinery are already triggered in the precancerous lesions described in this review, highlighting mTOR pathway proteins and eIFs to emphasize their putative clinical relevance. Here, we identified a lack of knowledge regarding the roles of single eIF proteins. A closer investigation will help to understand and treat HCC as well as the antecedent diseases.

Differential regulation of myc homologs by Wnt/ß-Catenin signaling in the early metazoan Hydra.

The c-Myc protein is a transcription factor with oncogenic potential controlling fundamental cellular processes. Homologs of the human c-myc protooncogene have been identified in the early diploblastic cnidarian Hydra (myc1, myc2). The ancestral Myc1 and Myc2 proteins display the principal design and biochemical properties of their vertebrate derivatives, suggesting that important Myc functions arose very early in metazoan evolution. c-Myc is part of a transcription factor network regulated by several upstream pathways implicated in oncogenesis and development. One of these signaling cascades is the Wnt/ß-Catenin pathway driving cell differentiation and developmental patterning, but also tumorigenic processes including aberrant transcriptional activation of c-myc in several human cancers. Here, we show that genetic or pharmacological stimulation of Wnt/ß-Catenin signaling in Hydra is accompanied by specific downregulation of myc1 at mRNA and protein levels. The myc1 and myc2 promoter regions contain consensus binding sites for the transcription factor Tcf, and Hydra Tcf binds to the regulatory regions of both promoters. The myc1 promoter is also specifically repressed in the presence of ectopic Hydra ß-Catenin/Tcf in avian cell culture. We propose that Hydra myc1 is a negative Wnt signaling target, in contrast to vertebrate c-myc, which is one of the best studied genes activated by this pathway. On the contrary, myc2 is not suppressed by ectopic ß-Catenin in Hydra and presumably represents the structural and functional c-myc ortholog. Our data implicate that the connection between ß-Catenin-mediated signaling and myc1 and myc2 gene regulation is an ancestral metazoan feature. Its impact on decision making in Hydra interstitial stem cells is discussed.

Stemness in Hydra - a current perspective.

Hydra is a classic and simple model for pattern formation and regeneration research. More recently, it has also been promoted as a model to study ancestral stem cell biology. Three independent cell lineages form the body of the polyp and exhibit characteristics of stem cell systems. In order to define differences in stemness between the ectodermal and endodermal epitheliomuscular cell lineages and the interstitial cell lineage, we compare cellular properties and decision making. We argue that these three lineages are expected to show substantial variation in their stemness-related gene regulatory networks. Finally, we discuss Wnt signalling pathways and Myc oncoproteins, which are beginning to offer a perspective on how proliferation and differentiation might be regulated.