Hepatocellular Ballooning is Due to Highly Pronounced Glycogenosis Potentially Associated with Steatosis and Metabolic Reprogramming.

Background And Aims: Hepatocellular ballooning is a common finding in chronic liver disease, mainly characterized by rarefied cytoplasm that often contains Mallory-Denk bodies (MDB). Ballooning has mostly been attributed to degeneration but its striking resemblance to glycogenotic/steatotic changes characterizing preneoplastic hepatocellular lesions in animal models and chronic human liver diseases prompts the question whether ballooned hepatocytes (BH) are damaged cells on the path to death or rather viable cells, possibly involved in neoplastic development.

Methods: Using specimens from 96 cirrhotic human livers, BH characteristics were assessed for their glycogen/lipid stores, enzyme activities, and proto-oncogenic signaling cascades by enzyme- and immunohistochemical approaches with serial paraffin and cryostat sections.

Clear cell hepatocellular carcinoma: origin, metabolic traits and fate of glycogenotic clear and ground glass cells.

Clear cell hepatocellular carcinoma (CCHCC) has hitherto been considered an uncommon, highly differentiated variant of hepatocellular carcinoma (HCC) with a relatively favorable prognosis. CCHCC is composed of mixtures of clear and/or acidophilic ground glass hepatocytes with excessive glycogen and/or fat and shares histology, clinical features and etiology with common HCCs. Studies in animal models of chemical, hormonal and viral hepatocarcinogenesis and observations in patients with chronic liver diseases prone to develop HCC have shown that the majority of HCCs are preceded by, or associated with, focal or diffuse excessive storage of glycogen (glycogenosis) which later may be replaced by fat (lipidosis/steatosis).

PI3K/AKT/mTOR pathway plays a major pathogenetic role in glycogen accumulation and tumor development in renal distal tubules of rats and men.

Activation of the PI3K/AKT/mTOR pathway is a crucial molecular event in human clear cell renal cell carcinoma (ccRCC), and is also upregulated in diabetic nephropathy. In diabetic rats metabolic changes affect the renal distal tubular epithelium and lead to glycogen-storing Armanni-Ebstein lesions (AEL), precursor lesions of RCC in the diabetes induced nephrocarcinogenesis model. These lesions resemble human sporadic clear cell tubules (CCT) and tumor cells of human ccRCC.

Glycogenotic hepatocellular carcinoma with glycogen-ground-glass hepatocytes: a heuristically highly relevant phenotype.

Glycogenotic hepatocellular carcinoma (HCC) with glycogen-ground-glass hepatocytes has recently been described as an allegedly "novel variant" of HCC, but neither the historical background nor the heuristic relevance of this observation were put in perspective. In the present contribution, the most important findings in animal models and human beings related to the emergence and further evolution of excessively glycogen storing (glycogenotic) hepatocytes with and without ground glass features during neoplastic development have been summarized. Glycogenotic HCCs with glycogen-ground-glass hepatocytes represent highly differentiated neoplasms which contain subpopulations of cells phenotypically resembling those of certain types of preneoplastic hepatic foci and benign hepatocellular neoplasms.

Specific alterations of carbohydrate metabolism are associated with hepatocarcinogenesis in mitochondrially impaired mice.

Friedreich's ataxia is an inherited neurodegenerative disease caused by the reduced expression of the mitochondrially active protein frataxin. We have previously shown that mice with a hepatocyte-specific frataxin knockout (AlbFxn(-/-)) develop multiple hepatic tumors in later life. In the present study, hepatic carbohydrate metabolism in AlbFxn(-/-) mice at an early and late life stage was analyzed.

Upregulation of the insulin receptor and type I insulin-like growth factor receptor are early events in hepatocarcinogenesis.

The molecular mechanisms underlying the development of hepatocellular carcinoma (HCC) are not yet fully understood. Preneoplastic foci of altered hepatocytes regularly precede HCC in various species. The predominant earliest type of foci of altered hepatocytes, the glycogen storage focus (GSF), shows an excess of glycogen (glycogenosis) in the cytoplasm.

Toxicogenomic analysis of N-nitrosomorpholine induced changes in rat liver: comparison of genomic and proteomic responses and anchoring to histopathological parameters.

A common animal model of chemical hepatocarcinogenesis was used to examine the utility of transcriptomic and proteomic data to identify early biomarkers related to chemically induced carcinogenesis. N-nitrosomorpholine, a frequently used genotoxic model carcinogen, was applied via drinking water at 120 mg/L to male Wistar rats for 7 weeks followed by an exposure-free period of 43 weeks. Seven specimens of each treatment group (untreated control and 120 mg/L N-nitrosomorpholine in drinking water) were sacrificed at nine time points during and after N-nitrosomorpholine treatment.

Renal carcinogenesis in models of diabetes in rats: metabolic changes are closely related to neoplastic development.

Aims/hypothesis: There is an increased risk of renal cell carcinoma (RCC) in human diabetes mellitus. We therefore examined the influence of hyperglycaemia and glucose-lowering treatment on nephrocarcinogenesis in rats.

Methods: Rats (n = 850), which were either spontaneously diabetic, streptozotocin-diabetic or normoglycaemic, were examined with special reference to Armanni-Ebstein lesions (AEL).

Comparison of mode of action of four hepatocarcinogens: a model-based approach.

Within the scope of the Rat Liver Foci Bioassay the model carcinogens N-nitrosomorpholine (NNM), 2-acetylaminoflouren (2-AAF), phenobarbital (PB), and clofibrate (CF) were analyzed concerning their potency and dose-response relationship to induce foci of altered hepatocytes (FAHs), which are known to be precursor lesions of liver adenoma and carcinoma. The medium-term experiment follows an initiation-promotion protocol using diethylnitrosamine (DEN) as initiator. The present report deals with the application of two biologically based models for hepatocarcinogenesis, the two-stage clonal expansion model (TSCEM), and a color-shift model with beta distributed growth rates (CSMbeta).

Investigating the formation and growth of alpha-particle radiation-induced foci of altered hepatocytes: a model-based approach.

The effect of alpha-particle radiation on the formation and increase in volume of preneoplastic liver lesions was investigated in an animal experiment. Mice were divided into four groups; two groups received different doses of the alpha-particle-labeled antibody (213)Bi-anti CD19 ((213)Bi-CD19), Thorotrast was administered to one group, and one group was left untreated. Hematoxylin and eosin-stained liver sections were evaluated for preneoplastic foci of altered hepatocytes 6, 12 and 17 months after treatment.

Lifelong exposure to di-(2-ethylhexyl)-phthalate induces tumors in liver and testes of Sprague-Dawley rats.

The plasticizer di-(2-ethylhexyl)-phthalate (DEHP) is the most important phthalate with respect to its production, use and occurrence in the environment. In standard carcinogenicity experiments with F344 rats and B6C3F1 mice, DEHP has been shown to induce hepatocellular tumors. Moreover, DEHP is strongly suspected to be a developmental and reproductive toxicant.

Protein phosphatase inhibitor-1 mRNA expression correlates with neoplastic transformation of epithelial liver cells and progression of hepatocellular carcinomas.

Protein phosphatase inhibitor-1 plays an important role in the regulation of glycogen metabolism through inhibition of protein phosphatase-1 activity, and it has been implicated in the regulation of cell growth. Using real-time quantitative RT-PCR, we studied the mRNA expression of inhibitor-1 in hepatocellular carcinomas induced in rats by oral administration of N-nitrosomorpholine, and in a non-tumorigenic liver cell line (C1I), that stores glycogen in excess during early passages. In late passages, glycogen is gradually lost concomitant with cell transformation.

Comments on R. Karbe and R. L. Kerlin (2002). Cystic degeneration/spongiosis hepatis (Toxicol Pathol 30 (2), 216-227).

Karbe and Kerlin have questioned the classification of spongiosis hepatis as a preneoplastic lesion or even a benign neoplasm, designated as spongiotic pericytoma, and have proposed to use the term cystic degeneration for this lesion in rats and fish. However, the reclassification of spongiosis as cystic degeneration is unwarranted for several reasons. In the rat, spongiosis hepatis represents a specific pathomorphologic entity, originating from the perisinusoidal (Ito) cells; it may occur spontaneously in aged animals but its number and size increases significantly after exposure to various (hepato)carcinogens.

WY-14,643-mediated promotion of hepatocarcinogenesis in connexin32-wild-type and connexin32-null mice.

Connexin32 (Cx32) is the major gap junction forming protein in liver and lack of functional Cx32 enhances hepatocarcinogenesis. Many tumour-promoting agents block gap junctional intercellular communication, which may favour clonal expansion of neoplastic cells. We recently demonstrated that liver tumourigenesis is accelerated in Cx32-wild-type but not in Cx32-null mice by the model tumour promoter phenobarbital (PB).

Significance of hepatic preneoplasia in risk identification and early detection of neoplasia.

Among the different types of liver tumor, hepatocellular neoplasms predominate by far in both animals and man. Consequently, preneoplastic foci of altered hepatocytes (FAH), preceding both hepatocellular adenomas and carcinomas, represent the most prevalent form of hepatic preneoplasia observed in animals for a long time, and identified in human chronic liver diseases associated with, or predisposing to, hepatocellular carcinomas more recently. Morphological, microbiochemical, and molecular biological approaches in situ revealed striking similarities in specific changes of the cellular phenotype of preneoplastic FAH developing in experimental and human hepatocarcinogenesis, irrespective of whether this was elicited by chemicals, hormones, viruses or radiation.

Relevance of hepatic preneoplasia for human hepatocarcinogenesis.

Different lesions have been suggested to represent preneoplastic conditions in human liver. They include liver cell dysplasia, separated in large-cell change (LCC) and small-cell change (SCC), adenomatoid hyperplasia, and the more recently identified foci of altered hepatocytes (FAH) and nodules of altered hepatocytes (NAH). FAH have been demonstrated to represent preneoplastic lesions in various animal models of hepatocarcinogenesis.

Prevalidation of a rat liver foci bioassay (RLFB) based on results from 1600 rats: a study report.

A rat liver foci bioassay (RLFB) based on an initiation-promotion protocol employing preneoplastic foci of altered hepatocytes (FAH) as an endpoint, was prevalidated in 5 different laboratories. FAH were identified by immunohistochemical demonstration of glutathione-S-transferase (placental form, GSTP) and by staining with hematoxilin/eosin (H&E), and their area fraction was quantified morphometrically. The four model hepatocarcinogens N-nitrosomorpholine, 2-acetylaminofluoren, phenobarbital, and clofibrate were selected according to characteristic differences in their presumed mode of action, and tested in a total of 1,600 male and female rats at 2 different dose levels.

Woodchuck hepatitis virus replication and antigen expression gradually decrease in preneoplastic hepatocellular lineages.

Background/aims: Hepatocellular carcinomas elicited in woodchucks by the woodchuck hepatitis virus (WHV) emerge gradually from parenchymal areas of minimal structural deviation via two predominant preneoplastic hepatocellular lineages, composed of either glycogenotic/basophilic or amphophilic/basophilic cell foci. In this study we analyzed WHV replication during neoplastic development in both lineages.

Methods: In minimal deviation areas, preneoplastic hepatocellular foci, and hepatocellular neoplasms, developing in 16 WHV-carriers 31-38 months after WHV-inoculation, the proportion of hepatocytes containing WHV replicative intermediates (as detected by in situ hybridization for WHV DNA) and immunoreactive for WHV core and surface antigens was assessed.

Hormonal and hormone-like effects eliciting hepatocarcinogenesis.

In various species, the manifestation of hepatocellular neoplasms is regularly preceded by preneoplastic foci of altered hepatocytes (FAH), the cellular phenotype of which is strikingly similar in experimental and human hepatocarcinogenesis, irrespective of the etiology of this process. The different types of FAH have been related to three main preneoplastic hepatocellular lineages: 1) the glycogenotic-basophilic cell lineage, 2) its xenomorphic-tigroid cell variant, and 3) the amphophilic-basophilic cell lineage. The predominant glycogenotic-basophilic and tigroid cell lineages developed especially after exposure to DNA-reactive chemicals, radiation, viruses, transgenic oncogenes and local hyperinsulinism.

Cholangiocarcinoma with a background of hepatitis B virus-associated cirrhosis.

Recently, hepatitis virus-associated chronic hepatitis or cirrhosis has been suggested to be involved in the pathogenesis of cholangiocarcinoma (CC). A 52-year-old man was diagnosed as CC with a background of hepatitis B virus (HBV)-dependent cirrhosis. A minute hepatic tumor was found during the follow-up, and was diagnosed as CC on percutaneous biopsy.

Detection and quantification of protein phosphatase inhibitor-1 gene expression in total rat liver and isolated hepatocytes.

The mRNA expression of protein phosphatase inhibitor-1 (inhibitor-1) in rat liver was demonstrated using highly sensitive semi-quantitative reverse transcription polymerase chain reaction (RT-PCR). Quantification by real-time RT-PCR (LightCycler technology) yielded the same copy number of inhibitor-1 mRNA in total rat liver and isolated hepatocytes (12 copies per cell). This novel finding shows that rat liver expresses indeed inhibitor-1 mRNA, albeit in low amounts.

Significance of hepatic preneoplasia for cancer chemoprevention.

Hepatic preneoplasia represents an early stage in neoplastic development, preceding both benign and malignant neoplasia. This applies particularly to foci of altered hepatocytes (FAH), that precede the manifestation of hepatocellular adenomas and carcinomas in all species investigated. Morphological, microbiochemical and molecular biological approaches in situ have provided evidence for striking similarities in specific changes of the cellular phenotype of preneoplastic FAH emerging in experimental and human hepatocarcinogenesis, irrespective of whether this was elicited by chemicals, hormones, radiation, viruses or, in animal models, by transgenic oncogenes or Helicobacter hepaticus.