Unknown,Transcriptomics,Genomics,Proteomics

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Oncogenic driver genes and the inflammatory microenvironment dictate liver tumor phenotype

ABSTRACT: The majority of hepatocellular carcinoma (HCC) develops in the background of chronic liver inflammation caused by viral hepatitis and alcoholic or non-alcoholic steatohepatitis. However, the impact of different types of chronic inflammatory microenvironments on the phenotypes of tumors generated by distinct oncogenes is largely unresolved. To address this issue, we generated murine liver tumors by constitutively active AKT-1 (AKT) and b-catenin (CAT) followed by induction of chronic liver inflammation by 3,5-diethoxycarbonyl-1,4-dihydrocollidine (DDC) and carbon tetrachloride (CCl4). Also, the impact of DDC-induced chronic liver inflammation was compared between two liver tumor models using a combination of AKT-CAT or AKT-NRASG12V. Treatment with DDC and CCl4 significantly facilitated the adenoma-to-carcinoma conversion and accelerated the growth of AKT-CAT tumors. Furthermore, DDC treatment altered the morphology of AKT-CAT tumors and caused loss of lipid droplets. Transcriptome analysis of AKT-CAT tumors revealed that cellular growth and proliferation was mainly affected by chronic inflammation. Integration with transcriptome profiles from human HCCs further demonstrated that AKT-CAT tumors generated in the context of chronic liver inflammation showed enrichment of poor prognosis gene sets or decrease of good prognosis gene sets. In contrast, DDC had a more subtle effect on AKT-NRASG12V tumors and primarily enhanced already existent tumor characteristics as supported by transcriptome analysis. However, it also reduced lipid droplets in AKT-NRASG12V tumors. Conclusion: Our study suggests that liver tumor phenotype is defined by a combination of driving oncogenes but also the nature of chronic liver inflammation. Total RNA isolated from AKT-CAT, AKT-CAT+DDC, AKT-CAT+CCl4, AKT-NRAS, AKT-NRAS+DCC, tumoral and non-tumoral tissue as well as PBS and DDC control tissue

ORGANISM(S): Mus musculus

SUBMITTER: Matthias Matter

PROVIDER: E-GEOD-77503 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress

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Project description:The liver has a remarkable capacity to regenerate and thus compensates for repeated injuries through toxic chemicals, drugs, alcohol, or malnutrition for decades. However, largely unknown is how and when alterations in the liver occur due to tolerable damaging insults. To that end, we induced repeated liver injuries over ten weeks in a mouse model injecting carbon tetrachloride (CCl4) twice a week. We lost 10% of the study animals within the first six weeks, which was accompanied by a steady deposition of extracellular matrix (ECM) regardless of metabolic activity of the liver. From week six onwards, all mice survived, and in these mice ECM deposition was rather reduced suggesting ECM remodelling as a liver response contributing to better coping with repeated injuries. The data of time-resolved paired transcriptome and proteome profiling of 18 mice was subjected to multi-level network inference, using Knowledge guided Multi-Omics Network inference (KiMONo), identified multi-level key markers exclusively associated with the injury-tolerant liver response. Interestingly, pathways of cancer and inflammation were lighting up and were validated using independent data sets compiled of 1034 samples from publicly available human cohorts. Interestingly, a yet undescribed link to lipid metabolism in this damage-tolerant phase was identified. Immunostaining revealed an unexpected accumulation of small lipid droplets (microvesicular steatosis) in parallel to a recovery of catabolic processes of the liver to pre-injury levels. Further, mild inflammation was experimentally validated. Taken together, we identified week six as a critical time point to switch the liver response program from an acute response that fosters ECM accumulation to a tolerant “survival” phase with pronounced deposition of small lipid droplets in hepatocytes potentially protecting against the repetitive injury with toxic chemicals. Our data suggest that microsteatosis formation plus a mild inflammatory state represent biomarkers and probably functional liver requirements to resist chronic damage.

Project description:Background and aims: Liver is a major target organ for alcohol-induced disease and the spectrum of pathological states elicited by alcohol in liver comprises steatosis, alcoholic steatohepatitis, progressive fibrosis and cirrhosis, conditions that may progress to hepatocellular carcinoma. Many experimental animal models of alcoholic steatohepatitis exist that vary in duration, mode of alcohol administration and the degree and types of liver injury produced. While most of these models, regardless whether alcohol is administered through liquid diet or intragastrically, produce steatohepatitis and mild fibrosis, it is widely acknowledged that these models fail to fully recapitulate key characteristics of severe forms of alcoholic liver disease, such as alcoholic hepatitis. Recent studies attempted to combine alcohol and fibrosis and achieved promising results in mouse models that achieve some of the key features of alcoholic liver disease accompanied by exacerbated fibrosis and acute renal injury. This study combined a chronic cholestatic liver fibrosis model induced by 3,5-diethoxycarbonyl-1,4-dihydrocollidine (DDC) with a mouse model of intragastric alcohol feeding. Methods: Adult male C57BL6/J mice were treated with 3,5-diethoxycarbonyl-1,4-dihydrocolidine (DDC) containing diet (0.05% w/w) to induce chronic liver fibrosis. Following DDC-induced fibrogenesis, ethyl alcohol (EtOH) (up to 27 g/ kg/day, up to 28 days) was administered continuously to mice via a gastric feeding tube (Tsukamoto-Frenchmodel of alcoholic liver disease). Results: Exposure to DDC or EtOH alone resulted in liver fibrosis or steatosis, respectively. Combined treatment with DDC and EtOH lead to an additive effect on liver injury, as evident by the development of hepatic inflammation, steatosis, and pericellular fibrosis, and by increased serum transaminase levels, compared to mice treated with either agent alone. Liver transcriptomic changes specific to combined treatment group included pathways involved in the cell cycle and DNA damage. Analyses of feces from these mice revealed alcohol-associated changes to the bile acid profile and gut microbiome. Conclusions: Mice treated with DDC and EtOH displayed several key characteristics of human alcoholic hepatitis, including pericellular fibrosis, increased hepatic bacterial load with dysbiosis, reduced capacity of the microbiome to synthesize secondary bile acids.

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Oncogenic driver genes and the inflammatory microenvironment dictate liver tumor phenotype

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