Transcriptomic and Proteomic Analysis of Clear Cell Foci (CCF) in the Human Non-Cirrhotic Liver Identifies Several Differentially Expressed Genes and Proteins with Functions in Cancer Cell Biology and Glycogen Metabolism.

Christoph Metzendorf,Baodong Sun,Silvia Ribback,Diego F Calvisi,Katharina Wineberger,Kristin Peters,Frank Dombrowski,Antonio Cigliano,Jenny Rausch,Daniela Mennerich,Thomas Kietzmann

doi:10.3390/molecules25184141

Christoph Metzendorf, Baodong Sun + Show 9 more

Open Access

https://doi.org/10.3390/molecules25184141

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Abstract

Clear cell foci (CCF) of the liver are considered to be pre-neoplastic lesions of hepatocellular adenomas and carcinomas. They are hallmarked by glycogen overload and activation of AKT (v-akt murine thymoma viral oncogene homolog)/mTOR (mammalian target of rapamycin)-signaling. Here, we report the transcriptome and proteome of CCF extracted from human liver biopsies by laser capture microdissection. We found 14 genes and 22 proteins differentially expressed in CCF and the majority of these were expressed at lower levels in CCF. Using immunohistochemistry, the reduced expressions of STBD1 (starch-binding domain-containing protein 1), USP28 (ubiquitin-specific peptidase 28), monad/WDR92 (WD repeat domain 92), CYB5B (Cytochrome b5 type B), and HSPE1 (10 kDa heat shock protein, mitochondrial) were validated in CCF in independent specimens. Knockout of Stbd1, the gene coding for Starch-binding domain-containing protein 1, in mice did not have a significant effect on liver glycogen levels, indicating that additional factors are required for glycogen overload in CCF. Usp28 knockout mice did not show changes in glycogen storage in diethylnitrosamine-induced liver carcinoma, demonstrating that CCF are distinct from this type of cancer model, despite the decreased USP28 expression. Moreover, our data indicates that decreased USP28 expression is a novel factor contributing to the pre-neoplastic character of CCF. In summary, our work identifies several novel and unexpected candidates that are differentially expressed in CCF and that have functions in glycogen metabolism and tumorigenesis.

Highlights

The early processes underlying human hepatocellular carcinogenesis are poorly understood.Very diverse conditions, such as the cirrhotic liver, non-cirrhotic liver with glycogen storage disease type I [1], as well as metabolic disorders, obesity [2], hyperinsulinism, alcohol abuse, and type 2 diabetes mellitus [3,4], are known to be risk factors for hepatocellular carcinoma (HCC) development
In the human cirrhotic liver, different types of foci of altered hepatocytes were described by Bannasch: glycogen-storing foci (clear cell foci (CCF), with pale hematoxylin and eosin (HE)
Using the intraportal pancreatic islet transplantation model of hepatocarcinogenesis [12,13,14,15], we found the AKT (v-akt murine thymoma viral oncogene homolog)/mTOR and the Ras/MAPK pathways to be activated throughout the development of Clear cell foci (CCF) to HCC, where they play important roles as major oncogenic downstream effectors of insulin signaling [16,17]

Summary

Introduction

The early processes underlying human hepatocellular carcinogenesis are poorly understood Very diverse conditions, such as the cirrhotic liver, non-cirrhotic liver with glycogen storage disease type I [1], as well as metabolic disorders (alpha-1-antitrypsin deficiency and hemochromatosis), obesity [2], hyperinsulinism, alcohol abuse, and type 2 diabetes mellitus [3,4], are known to be risk factors for hepatocellular carcinoma (HCC) development. To better understand the mechanisms underlying carcinogenesis, it is important to better characterize the precursor stages—pre-neoplastic lesions—for improving early diagnosis and treatment of HCC. This is increasingly important as primary liver cancer is the fifth most frequent malignancy worldwide and the proportion of HCCs in the background of type 2 diabetes and obesity is becoming more common [2].

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