| 1. |
- Godoy, Patricio, et al.
(författare)
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Recent advances in 2D and 3D in vitro systems using primary hepatocytes, alternative hepatocyte sources and non-parenchymal liver cells and their use in investigating mechanisms of hepatotoxicity, cell signaling and ADME
- 2013
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Ingår i: Archives of Toxicology. - : Springer Science and Business Media LLC. - 0340-5761 .- 1432-0738. ; 87:8, s. 1315-1530
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Forskningsöversikt (refereegranskat)abstract
- This review encompasses the most important advances in liver functions and hepatotoxicity and analyzes which mechanisms can be studied in vitro. In a complex architecture of nested, zonated lobules, the liver consists of approximately 80 % hepatocytes and 20 % non-parenchymal cells, the latter being involved in a secondary phase that may dramatically aggravate the initial damage. Hepatotoxicity, as well as hepatic metabolism, is controlled by a set of nuclear receptors (including PXR, CAR, HNF-4 alpha, FXR, LXR, SHP, VDR and PPAR) and signaling pathways. When isolating liver cells, some pathways are activated, e.g., the RAS/MEK/ERK pathway, whereas others are silenced (e.g. HNF-4 alpha), resulting in up- and downregulation of hundreds of genes. An understanding of these changes is crucial for a correct interpretation of in vitro data. The possibilities and limitations of the most useful liver in vitro systems are summarized, including three-dimensional culture techniques, co-cultures with non-parenchymal cells, hepatospheres, precision cut liver slices and the isolated perfused liver. Also discussed is how closely hepatoma, stem cell and iPS cell-derived hepatocyte-like-cells resemble real hepatocytes. Finally, a summary is given of the state of the art of liver in vitro and mathematical modeling systems that are currently used in the pharmaceutical industry with an emphasis on drug metabolism, prediction of clearance, drug interaction, transporter studies and hepatotoxicity. One key message is that despite our enthusiasm for in vitro systems, we must never lose sight of the in vivo situation. Although hepatocytes have been isolated for decades, the hunt for relevant alternative systems has only just begun.
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| 2. |
- Hellerbrand, Claus, et al.
(författare)
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Cylindromatosis-A Protective Molecule against Liver Diseases.
- 2016
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Ingår i: Medicinal Research Reviews. - : Wiley. - 1098-1128 .- 0198-6325. ; 36:2, s. 342-359
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Forskningsöversikt (refereegranskat)abstract
- Cylindromatosis (CYLD) is a deubiquitination enzyme involved in the regulation of different cellular processes including inflammation, fibrosis, and cancer. The function of CYLD is via deubiquitination of specific substrates in different signaling pathways including NF-κB, Notch, and JNK. CYLD contributes to hepatic homeostasis and restoration upon liver injury. Mutation or disruption of the activity of CYLD in animals aggravates acute as well as chronic liver injury and promotes development and progression of hepatocellular cancer. This is mediated by a shift of the balance toward pro-inflammatory, pro-fibrogenic, and pro-oncogenic pathways. In this review, we will explain the liver-associated signaling pathways that CYLD regulates in hepatocytes and nonparenchymal liver cells under physiological and pathological conditions. We will also describe the most recent findings concerning CYLD-mediated downstream signaling in the liver in situations such as injury, infection, inflammation, and cancer. Furthermore, we will discuss the potential of novel diagnostic tools and treatment strategies utilizing CYLD and its target genes.
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| 3. |
- Hellerbrand, Claus, et al.
(författare)
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Reduced expression of CYLD in human colon and hepatocellular carcinomas
- 2007
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Ingår i: Carcinogenesis. - : Oxford University Press (OUP). - 0143-3334 .- 1460-2180. ; 28:1, s. 21-27
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Tidskriftsartikel (refereegranskat)abstract
- CYLD was originally identified as a tumor suppressor that is mutated in familial cylindromatosis. Recent studies suggested a role for CYLD in nuclear factor-kappaB (NF-kappaB) regulation. NF-kappaB activation has been connected with multiple aspects of oncogenesis but the underlying molecular mechanisms of persistent NF-kappaB activation in tumors remain largely unknown. Thus, we evaluated CYLD transcription in different colon and hepatocellular carcinoma cell lines and tissue samples, respectively. CYLD was downregulated or lost in all tumor cell lines investigated as compared with primary human colonic epithelial cells and hepatocytes, respectively. Further, quantitative PCR analysis revealed reduced CYLD mRNA expression in most tumor samples compared with non-tumorous tissue. Analysis on protein level confirmed these findings. Functional assays with CYLD transfected cell lines revealed that CYLD expression decreased NF-kappaB activity. Thus, functional relevant loss of CYLD expression may contribute to tumor development and progression, and may provide a new target for therapeutic strategies.
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| 4. |
- Kuphal, Silke, et al.
(författare)
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UVB radiation represses CYLD expression in melanocytes
- 2017
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Ingår i: Oncology Letters. - : Spandidos Publications. - 1792-1074 .- 1792-1082. ; 14:6, s. 7262-7268
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Tidskriftsartikel (refereegranskat)abstract
- CYLD lysine 63 deubiquitinase (CYLD) was originally identified as a tumor suppressor that is mutated in familial cylindromatosis. Unlike in cylindromatosis, downregulation of the deubiquitinase CYLD in melanoma, a highly aggressive tumor, is not caused by mutations in the CYLD gene, but rather by a constitutive and high expression of the snail family transcriptional repressor 1 (SNAIL1). A reduced CYLD level leads to B-cell lymphoma-3/p50/p52-dependent nuclear factorκB activation, which in turn triggers the expression of genes such as cyclin D1 and N-cadherin. Elevated levels of cyclin D1 and N-cadherin promote melanoma proliferation and invasion. By analyzing the regulation of CYLD expression in melanocytes, the present study identified a signaling pathway that is regulated in response to ultraviolet B (UVB) radiation in melanocytes. UVB light leads to an extracellular signal-regulated kinase-mediated induction of SNAIL1 and subsequent downregulation of CYLD expression in normal human epithelial melanocytes. The UVB-mediated suppression of CYLD in melanocytes may have a key role in the reaction to UV stimuli, and may also potentially be involved in the early malignant transformation processes.
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| 5. |
- Massoumi, Ramin, et al.
(författare)
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Down-regulation of CYLD expression by Snail promotes tumor progression in malignant melanoma
- 2009
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Ingår i: Journal of Experimental Medicine. - : Rockefeller University Press. - 1540-9538 .- 0022-1007. ; 206:1, s. 221-232
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Tidskriftsartikel (refereegranskat)abstract
- High malignancy and early metastasis are hallmarks of melanoma. Here, we report that the transcription factor Snail1 inhibits expression of the tumor suppressor CYLD in melanoma. As a direct consequence of CYLD repression, the protooncogene BCL-3 translocates into the nucleus and activates Cyclin D1 and N-cadherin promoters, resulting in proliferation and invasion of melanoma cells. Rescue of CYLD expression in melanoma cells reduced proliferation and invasion in vitro and tumor growth and metastasis in vivo. Analysis of a tissue microarray with primary melanomas from patients revealed an inverse correlation of Snail1 induction and loss of CYLD expression. Importantly, tumor thickness and progression-free and overall survival inversely correlated with CYLD expression. Our data suggest that Snail1-mediated suppression of CYLD plays a key role in melanoma malignancy.
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| 6. |
- Rajeswara, Pannem Rao, et al.
(författare)
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CYLD controls c-MYC expression through the JNK-dependent signaling pathway in hepatocellular carcinoma.
- 2014
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Ingår i: Carcinogenesis. - : Oxford University Press (OUP). - 0143-3334 .- 1460-2180. ; 35:2, s. 461-468
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Tidskriftsartikel (refereegranskat)abstract
- Post-translational modification of different proteins via direct ubiquitin attachment is vital for mediating various cellular processes. CYLD, a deubiquitination enzyme, is able to cleave the polyubiquitin chains from the substrate, and to regulate different signaling pathways. Loss, or reduced expression, of CYLD is observed in different types of human cancer, such as hepatocellular carcinoma (HCC). However, the molecular mechanism by which CYLD affects cancerogenesis has to date not been unveiled. The aim of the present study was to examine how CYLD regulates cellular functions and signaling pathways during hepatocancerogenesis. We found that mice lacking CYLD were highly susceptible to chemically induced liver cancer. The mechanism behind proved to be an elevated proliferation rate of hepatocytes, owing to sustained JNK1-mediated signaling via ubiquitination of TRAF2 and expression of c-MYC. Overexpression of wild type CYLD in an HCC cell lines prevented cell proliferation, without affecting apoptosis, adhesion, and migration. A combined immunohistochemical and tissue microarray analysis of 81 human HCC tissues revealed that CYLD expression is negatively correlated with expression of proliferation marker Ki-67 and c-MYC. To conclude, we found that downregulation of CYLD induces tumor cell proliferation, consequently contributing to the aggressive growth of HCC. Our findings suggest that CYLD holds potential to serve as a marker for HCC progression, and its link to c-MYC via JNK1 may provide the foundation for new therapeutic strategies for HCC-patients.
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| 7. |
- Rajeswara, Pannem Rao, et al.
(författare)
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CYLD regulates HGF expression in hepatic stellate cells via interaction with HDAC7.
- 2014
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Ingår i: Hepatology. - : Ovid Technologies (Wolters Kluwer Health). - 1527-3350 .- 0270-9139. ; 60:3, s. 1066-1081
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Tidskriftsartikel (refereegranskat)abstract
- Hepatic fibrosis is considered as a physiological wound-healing response to liver injury. The process involves several factors, such as the hepatocyte growth factor (HGF), which restrain hepatic injury and facilitate the reversibility of the fibrotic reaction in response to an acute insult. Chronic liver injury and sustained inflammation cause progressive fibrosis and, ultimately, organ dysfunction. The mechanisms tipping the balance from restoration to progressive liver tissue scarring are not well understood. In the present study, we identify a mechanism in which the tumor suppressor gene, cylindromatosis (CYLD), confers protection from hepatocellular injury and fibrosis. Mice lacking CYLD (CYLD(-/-) ) were highly susceptible to hepatocellular damage, inflammation and fibrosis and revealed significantly lower hepatic HGF-levels compared with wild-type animals. Exogenous application of HGF rescued the liver injury phenotype of CYLD(-/-) mice. In the absence of CYLD, gene transcription of HGF in hepatic stellate cells was repressed through the binding of histone deacetylase 7 (HDAC7) to the promoter of HGF. In wildtype cells, CYLD removed HDAC7 from HGF promoter and induced HGF expression. Noteworthy, this interaction occurred independent of deubiquitinating activity of CYLD. Conclusions: Our findings highlight a novel link between CYLD and HDAC7, offering mechanistic insight into the contribution of these proteins to the progression of liver disease. Thus, through the regulation of the HGF level, CYLD ameliorates hepatocellular damage and liver fibrogenesis. (Hepatology 2014).
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