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Spontaneous hepatocarcinogenesis in farnesoid X receptor-null mice.

ABSTRACT: The farnesoid X receptor (FXR) controls the synthesis and transport of bile acids (BAs). Mice lacking expression of FXR, designated Fxr-null, have elevated levels of serum and hepatic BAs and an increase in BA pool size. Surprisingly, at 12 months of age, male and female Fxr-null mice had a high incidence of degenerative hepatic lesions, altered cell foci and liver tumors including hepatocellular adenoma, carcinoma and hepatocholangiocellular carcinoma, the latter of which is rarely observed in mice. At 3 months, Fxr-null mice had increased expression of the proinflammatory cytokine IL-1beta mRNA and elevated beta-catenin and its target gene c-myc. They also had increased cell proliferation as revealed by increased PCNA mRNA and BrdU incorporation. These studies reveal a potential role for FXR and BAs in hepatocarcinogenesis.

SUBMITTER: Kim I

PROVIDER: S-EPMC1858639 | biostudies-literature | 2007 May

REPOSITORIES: biostudies-literature

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Spontaneous hepatocarcinogenesis in farnesoid X receptor-null mice.

Kim Insook I Morimura Keiichirou K Shah Yatrik Y Yang Qian Q Ward Jerrold M JM Gonzalez Frank J FJ

Carcinogenesis 20061220 5

The farnesoid X receptor (FXR) controls the synthesis and transport of bile acids (BAs). Mice lacking expression of FXR, designated Fxr-null, have elevated levels of serum and hepatic BAs and an increase in BA pool size. Surprisingly, at 12 months of age, male and female Fxr-null mice had a high incidence of degenerative hepatic lesions, altered cell foci and liver tumors including hepatocellular adenoma, carcinoma and hepatocholangiocellular carcinoma, the latter of which is rarely observed in ...[more]

PMID: 17183066

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Farnesoid X receptor ablation sensitizes mice to hepatitis b virus X protein-induced hepatocarcinogenesis.

Project description:Chronic hepatitis B virus infection is a major risk factor for hepatocellular carcinoma (HCC). Hepatitis B virus X protein (HBx) is a hepatitis B virus protein that has multiple cellular functions, but its role in HCC pathogenesis has been controversial. Farnesoid X receptor (FXR) is a nuclear receptor with activities in anti-inflammation and inhibition of hepatocarcinogenesis. However, whether or how FXR can impact hepatitis B virus/HBx-induced hepatocarcinogenesis remains unclear. In this study, we showed that HBx can interact with FXR and function as a coactivator of FXR. Expression of HBx in vivo enhanced FXR-responsive gene regulation. HBx also increased the transcriptional activity of FXR in a luciferase reporter gene assay. The HBx-FXR interaction was confirmed by coimmunoprecipitation and glutathione S-transferase pull-down assays, and the FXR activation function 1 domain was mapped to bind to the third α helix in the C terminus of HBx. We also found that the C-terminally truncated variants of HBx, which were found in clinical HCC, were not effective at transactivating FXR. Interestingly, recruitment of the full-length HBx, but not the C-terminally truncated HBx, enhanced the binding of FXR to its response element. In vivo, FXR ablation markedly sensitized mice to HBx-induced hepatocarcinogenesis.ConclusionsWe propose that transactivation of FXR by full-length HBx may represent a protective mechanism to inhibit HCC and that this inhibition may be compromised upon the appearance of C-terminally truncated HBx or when the expression and/or activity of FXR is decreased. (Hepatology 2017;65:893-906).

| S-EPMC5319891 | biostudies-literature

Increased activation of the Wnt/?-catenin pathway in spontaneous hepatocellular carcinoma observed in farnesoid X receptor knockout mice.

Project description:Farnesoid X receptor (FXR), the primary bile acid-sensing nuclear receptor, also is known for its anticancer properties. It is known that FXR deficiency in mice results in spontaneous hepatocellular carcinoma (HCC), but the mechanisms are not completely understood. We report that sustained activation of the Wnt/?-catenin pathway is associated with spontaneous HCC in FXR-knockout (KO) mice. HCC development was studied in FXR-KO mice at 3, 8, and 14 months of age. No tumors were observed at either 3 or 8 months, but the presence of HCC was observed in 100% of the FXR-KO mice at the age of 14 months. Further analysis revealed no change in ?-catenin activation in the livers of 3-month-old FXR-KO mice, but a moderate increase was observed in 8-month-old FXR-KO mice. ?-Catenin activation further increased significantly in 14-month-old tumor-bearing mice. Further analysis revealed that two independent mechanisms might be involved in ?-catenin activation in the livers of FXR-KO mice. Activation of canonical Wnt signaling was evident as indicated by increased Wnt4 and dishevelled expression along with glycogen synthase kinase-3? inactivation. We also observed decreased expression of E-cadherin, a known regulator of ?-catenin, in FXR-KO mice. The decrease in E-cadherin expression was accompanied by increased expression of its transcriptional repressor, Snail. Consistent with the increased HCC in FXR-KO mice, we observed a significant decrease in FXR expression and activity in human HCC samples. Taken together, these data indicate that a temporal increase in the activation of Wnt/?-catenin is observed during spontaneous HCC development in FXR-KO mice and is potentially critical for tumor development.

| S-EPMC3126651 | biostudies-literature

Rlip depletion prevents spontaneous neoplasia in TP53 null mice.

Project description:TP53 (p53) is a tumor suppressor whose functions are lost or altered in most malignancies. p53 homozygous knockout (p53-/-) mice uniformly die of spontaneous malignancy, typically T-cell lymphoma. RALBP1 (RLIP76, Rlip) is a stress-protective, mercapturic acid pathway transporter protein that also functions as a Ral effector involved in clathrin-dependent endocytosis. In stark contrast to p53-/- mice, Rlip-/- mice are highly resistant to carcinogenesis. We report here that partial Rlip deficiency induced by weekly administration of an Rlip-specific phosphorothioate antisense oligonucleotide, R508, strongly inhibited spontaneous as well as benzo(a)pyrene-induced carcinogenesis in p53-/- mice. This treatment effectively prevented large-scale methylomic and transcriptomic abnormalities suggestive of inflammation found in cancer-bearing p53-/- mice. The remarkable efficiency with which Rlip deficiency suppresses spontaneous malignancy in p53-/- mice has not been observed with any previously reported pharmacologic or genetic intervention. These findings are supported by cross-breeding experiments demonstrating that hemizygous Rlip deficiency also reduces the spontaneous malignancy phenotype of p53+/- mice. Rlip is found on the cell surface, and antibodies directed against Rlip were found to inhibit growth and promote apoptosis of cell lines as effectively as Rlip siRNA. The work presented here investigates several features, including oxidative DNA damage of the Rlip-p53 association in malignant transformation, and offers a paradigm for the mechanisms of tumor suppression by p53 and the prospects of suppressing spontaneous malignancy in hereditary cancer syndromes such as Li-Fraumeni.

| S-EPMC5899455 | biostudies-literature

Transcription profiling of liver from farnesoid X receptor knockout mice

Project description:Expression profiling of whole body (WB) FXR knockout (KO) mice (FXR WB KO), liver-specific FXR KO mice (AFXR Cre+) and enterocyte specific FXR KO mice (VFXR Cre+) on a C57BL/6J genetic background Whole body (WB) FXR knockout (KO) mice (FXR WB KO), liver-specific FXR KO mice (AFXR Cre+) and enterocyte specific FXR KO mice (VFXR Cre+) on a C57BL/6J genetic background were bred and maintained in the laboratory animal research facility at the University of Kansas Medical Center in rooms under a 12-hour light-dark cycle. All experiments used 10-16 week-old male mice. FXR was activated by treatment with the FXR synthetic agonist, GW4064, at 150 mg/kg. GW4064 or vehicle was administered by oral gavage at 6 p.m., followed by a second administration at 8 a.m. the next morning. Two hours later, the liver was harvested.

2014-01-31 | E-GEOD-54557 | biostudies-arrayexpress

Impaired Intestinal Farnesoid X Receptor Signaling in Cystic Fibrosis Mice.

Project description:Background & aimsThe bile acid (BA)-activated farnesoid X receptor (FXR) controls hepatic BA synthesis and cell proliferation via the intestinal hormone fibroblast growth factor 19. Because cystic fibrosis (CF) is associated with intestinal dysbiosis, anomalous BA handling, and biliary cirrhosis, we investigated FXR signaling in CF.MethodsIntestinal and hepatic expression of FXR target genes and inflammation markers was assessed in Cftr null mice and controls. Localization of the apical sodium-dependent BA transporter was assessed, and BAs in gastrointestinal tissues were analyzed. The CF microbiota was characterized and FXR signaling was investigated in intestinal tissue and organoids.ResultsIleal murine fibroblast growth factor 19 ortholog (Fgf15) expression was strongly reduced in CF mice, compared with controls. Luminal BA levels and localization of apical sodium-dependent BA transporter was not affected, and BAs induced Fgf15 up to normal levels in CF ileum, ex vivo, and CF organoids. CF mice showed a dysbiosis that was associated with a marked up-regulation of genes involved in host-microbe interactions, including those involved in mucin glycosylation, antimicrobial defense, and Toll-like receptor signaling. Antibiotic treatment reversed the up-regulation of inflammatory markers and restored intestinal FXR signaling in CF mice. Conversely, FXR-dependent gene induction in ileal tissue and organoids was repressed by bacterial lipopolysaccharide and proinflammatory cytokines, respectively. Loss of intestinal FXR activity was associated with a markedly blunted hepatic trophic response to oral BA supplementation, and with impaired repression of Cyp7a1, the gene encoding the rate-limiting enzyme in BA synthesis.ConclusionsIn CF mice, the gut microbiota represses intestinal FXR activity, and, consequently, FXR-dependent hepatic cell proliferation and feedback control of BA synthesis.

| S-EPMC6881665 | biostudies-literature

Farnesoid X receptor (FXR) gene deficiency impairs urine concentration in mice.

Project description:The farnesoid X receptor (FXR) is a ligand-activated transcription factor belonging to the nuclear receptor superfamily. FXR is mainly expressed in liver and small intestine, where it plays an important role in bile acid, lipid, and glucose metabolism. The kidney also has a high FXR expression level, with its physiological function unknown. Here we demonstrate that FXR is ubiquitously distributed in renal tubules. FXR agonist treatment significantly lowered urine volume and increased urine osmolality, whereas FXR knockout mice exhibited an impaired urine concentrating ability, which led to a polyuria phenotype. We further found that treatment of C57BL/6 mice with chenodeoxycholic acid, an FXR endogenous ligand, significantly up-regulated renal aquaporin 2 (AQP2) expression, whereas FXR gene deficiency markedly reduced AQP2 expression levels in the kidney. In vitro studies showed that the AQP2 gene promoter contained a putative FXR response element site, which can be bound and activated by FXR, resulting in a significant increase of AQP2 transcription in cultured primary inner medullary collecting duct cells. In conclusion, the present study demonstrates that FXR plays a critical role in the regulation of urine volume, and its activation increases urinary concentrating capacity mainly via up-regulating its target gene AQP2 expression in the collecting ducts.

| S-EPMC3926076 | biostudies-literature

Farnesoid X Receptor Protects against Kidney Injury in Uninephrectomized Obese Mice.

Project description:Activation of the farnesoid X receptor (FXR) has indicated a therapeutic potential for this nuclear bile acid receptor in the prevention of diabetic nephropathy and obesity-induced renal damage. Here, we investigated the protective role of FXR against kidney damage induced by obesity in mice that had undergone uninephrectomy, a model resembling the clinical situation of kidney donation by obese individuals. Mice fed a high-fat diet developed the core features of metabolic syndrome, with subsequent renal lipid accumulation and renal injury, including glomerulosclerosis, interstitial fibrosis, and albuminuria. The effects were accentuated by uninephrectomy. In human renal biopsies, staining of 4-hydroxynonenal (4-HNE), glucose-regulated protein 78 (Grp78), and C/EBP-homologous protein, markers of endoplasmic reticulum stress, was more prominent in the proximal tubules of 15 obese patients compared with 16 non-obese patients. In mice treated with the FXR agonist obeticholic acid, renal injury, renal lipid accumulation, apoptosis, and changes in lipid peroxidation were attenuated. Moreover, disturbed mitochondrial function was ameliorated and the mitochondrial respiratory chain recovered following obeticholic acid treatment. Culturing renal proximal tubular cells with free fatty acid and FXR agonists showed that FXR activation protected cells from free fatty acid-induced oxidative stress and endoplasmic reticulum stress, as denoted by a reduction in the level of reactive oxygen species staining and Grp78 immunostaining, respectively. Several genes involved in glutathione metabolism were induced by FXR activation in the remnant kidney, which was consistent with a decreased glutathione disulfide/glutathione ratio. In summary, FXR activation maintains endogenous glutathione homeostasis and protects the kidney in uninephrectomized mice from obesity-induced injury.

| S-EPMC4732222 | biostudies-literature

Cell-Autonomous Role of EGFR in Spontaneous Duodenal Tumors in LRIG1 Null Mice.

Project description: Not available

| S-EPMC8413138 | biostudies-literature

Transcription profiling of liver from farnesoid X receptor knockout mice

2014-01-31 | GSE54557 | GEO

Genomic analysis of hepatic farnesoid X receptor binding sites reveals altered binding in obesity and direct gene repression by farnesoid X receptor in mice.

Project description:UnlabelledThe nuclear bile acid receptor, farnesoid X receptor (FXR), is an important transcriptional regulator of liver metabolism. Despite recent advances in understanding its functions, how FXR regulates genomic targets and whether the transcriptional regulation by FXR is altered in obesity remain largely unknown. Here, we analyzed hepatic genome-wide binding sites of FXR in healthy and dietary obese mice by chromatin immunoprecipitation sequencing (ChIP-seq) analysis. A total of 15,263 and 5,272 FXR binding sites were identified in livers of healthy and obese mice, respectively, after a short 1-hour treatment with the synthetic FXR agonist, GW4064. Of these sites, 7,440 and 2,344 were detected uniquely in healthy and obese mice. FXR-binding sites were localized mostly in intergenic and intron regions at an inverted repeat 1 motif in both groups, but also clustered within 1 kilobase of transcription start sites. FXR-binding sites were detected near previously unknown target genes with novel functions, including diverse cellular signaling pathways, apoptosis, autophagy, hypoxia, inflammation, RNA processing, metabolism of amino acids, and transcriptional regulators. Further analyses of randomly selected genes from both healthy and obese mice suggested that more FXR-binding sites are likely functionally inactive in obesity. Surprisingly, occupancies of FXR, retinoid X receptor alpha, RNA polymerase II, and epigenetic gene activation and repression histone marks, and messenger RNA levels of genes examined, suggested that direct gene repression by agonist-activated FXR is common.ConclusionComparison of genomic FXR-binding sites in healthy and obese mice suggested that FXR transcriptional signaling is altered in dietary obese mice, which may underlie aberrant metabolism and liver function in obesity.

| S-EPMC3343176 | biostudies-literature

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