Hepatocellular carcinomas are well-vascularized tumors; the endothelial cells in these tumors have a specific phenotype. Our aim was to develop a new approach for tumor-specific drug delivery with monoclonal antibody targeting of endothelial ligands. CD146, a molecule expressed on the endothelial surface of hepatocellular carcinoma, was identified as a promising candidate for targeting. In the present study, endothelial cells immediately captured circulating anti-CD146 (ME-9F1) antibody, while antibody binding in tumors was significantly higher than in hepatic endothelium. Macroscopically, after intravenous injection, there were no differences in the mean accumulation of anti-CD146 antibody in tumor compared to liver tissue , due to a compensating higher blood vessel density in the liver tissue. Additional blockade of nontumoral epitopes and intra-arterial administration, improved selective antibody capture in the tumor microvasculature and largely prevented antibody distribution in the lung and liver. The potential practical use of this approach was demonstrated by imaging of radionuclide-labeled ME-9F1 antibody, which showed excellent tumor-selective uptake. Our results provide a promising principle for the use of endothelial markers for intratumoral drug delivery. Tumor endothelium-based access might offer new opportunities for the imaging and therapy of hepatocellular carcinoma and other liver malignancies.
The mammalian timeless (TIM) protein interacts with proteins of the endogenous clock and essentially contributes to the circadian rhythm. In addition, TIM is involved in maintenance of chromosome integrity, growth control and development. Thus, we hypothesized that TIM may exert a potential protumorigenic function in human hepatocarcinogenesis. TIM was overexpressed in a subset of human HCCs both at the mRNA and the protein level. siRNA-mediated knockdown of TIM reduced cell viability due to the induction of apoptosis and G2 arrest. The latter was mediated via CHEK2 phosphorylation. In addition, siRNA-treated cells showed a significantly reduced migratory capacity and reduced expression levels of various proteins. Mechanistically, TIM directly interacts with the eukaryotic elongation factor 1A2 (EEF1A2), which binds to actin filaments to promote tumor cell migration. siRNA-mediated knockdown of TIM reduced EEF1A2 protein levels thereby affecting ribosomal protein biosynthesis. Thus, overexpression of TIM exerts oncogenic function in human HCCs, which is mediated via CHEK2 and EEF1A2.
The S100A8/A9 heterodimer (calprotectin) acts as a danger signal when secreted into the extracellular space during inflammation and tissue damage. It promotes proinflammatory responses and drives tumor development in different models of inflammation-driven carcinogenesis. S100A8/A9 is strongly expressed in several human tumors, including hepatocellular carcinoma (HCC). Apart from this evidence, the role of calprotectin in hepatocyte transformation and tumor microenvironment is still unknown. The aim of this study was to define the function of S100A8/A9 in inflammation-driven HCC. Mice lacking S100a9 were crossed with the Mdr2(-) (/) (-) model, a prototype of inflammation-induced HCC formation. S100a9(-) (/) (-) Mdr2(-) (/) (-) (dKO) mice displayed no significant differences in tumor incidence or multiplicity compared to Mdr2(-) (/) (-) animals. Chronic liver inflammation, fibrosis and oval cell activation were not affected upon S100a9 deletion. Our data demonstrate that, although highly upregulated, calprotectin is dispensable in the onset and development of HCC, and in the maintenance of liver inflammation.
The cell adhesion molecule E-cadherin has critical functions in development and carcinogenesis. Impaired expression of E-cadherin has been associated with disrupted tissue homeostasis, progression of cancer and a worse patient prognosis. So far, the role of E-cadherin in homeostasis and carcinogenesis of the liver is not well understood. By use of a mouse model with liver-specific deletion of E-cadherin and administration of the carcinogen diethylnitrosamine, we demonstrate that loss of E-cadherin expression in hepatocytes results in acceleration of the growth of hepatocellular carcinoma (HCC). In contrast, liver regeneration is not disturbed in mice lacking E-cadherin expression in hepatocytes. In human HCC, we observed four different expression patterns of E-cadherin. Notably, atypical cytosolic expression of E-cadherin was positively correlated with a poorer patient prognosis. The median overall survival of patients with HCC expressing E-cadherin on the membrane only was 221 weeks (95% confidence interval: 51-391) compared with 131 weeks in patients with cytosolic expression (95% confidence interval: 71-191 weeks; P < 0.05). In conclusion, we demonstrate that impaired expression of E-cadherin promotes hepatocellular carcinogenesis and is associated with a worse prognosis in humans.
The ubiquitously expressed transcriptional regulator Serum Response Factor (SRF) is controlled by both Ras/MAPK and Rho/actin signaling pathways, which are frequently activated in hepatocellular carcinoma (HCC). We generated SRF-VP16(iHep) mice, which conditionally express constitutively active SRF-VP16 in hepatocytes, thereby controlling subsets of both Ras/MAPK- and Rho/actin-stimulated target genes. All SRF-VP16(iHep) mice develop hyper-proliferative liver nodules that progresses to lethal HCC. Some mHCCs acquire Ctnnb1 mutations equivalent to those in hHCC. Resulting transcript signatures mirror those of a distinct subgroup of hHCCs, with shared activation of oncofetal genes including Igf2, correlating with CpG hypo-methylation at the imprinted Igf2/H19 locus. Conclusion: SRF-VP16(iHep) mHCC reveal convergent Ras/MAPK and Rho/actin signaling as highly oncogenic driver mechanism for hepato-carcinogenesis. This suggests simultaneous inhibition of Ras/MAPK and Rho/actin signaling as treatment strategy in human HCC therapy. (Hepatology 2014;).
Proteins of the karyopherin superfamily including importins and exportins represent an essential part of the nucleocytoplasmic transport machinery. However, the functional relevance and regulation of karyopherins in hepatocellular carcinoma (HCC) is poorly understood. Here we identified cellular apoptosis susceptibility (CAS, exportin-2) and its transport substrate importin-?1 (imp-?1) among significantly up-regulated transport factor genes in HCC. Disruption of the CAS/imp-?1 transport cycle by RNAi in HCC cell lines resulted in decreased tumor cell growth and increased apoptosis. The apoptotic phenotype upon CAS depletion could be recapitulated by direct knockdown of the X-linked inhibitor of apoptosis (XIAP) and partially reverted by XIAP overexpression. In addition, XIAP and CAS mRNA expression levels were correlated in HCC patient samples (r=0.463; P<0.01), supporting the in vivo relevance of our findings. Furthermore, quantitative mass spectrometry analyses of murine HCC samples (p53-/- versus p53+/+) indicated higher protein expression of CAS and imp-?1 in p53-/- tumors. Consistent with a role of p53 in regulating the CAS/imp-?1 transport cycle, we observed that both transport factors were repressed upon p53 induction in a p21-dependent manner.
In solid tumors, resistance to therapy inevitably develops upon treatment with cytotoxic drugs or molecularly targeted therapies. Here, we describe a system that enables pooled shRNA screening directly in mouse hepatocellular carcinomas (HCC) in vivo to identify genes likely to be involved in therapy resistance. Using a focused shRNA library targeting genes located within focal genomic amplifications of human HCC, we screened for genes whose inhibition increased the therapeutic efficacy of the multikinase inhibitor sorafenib. Both shRNA-mediated and pharmacological silencing of Mapk14 (p38?) were found to sensitize mouse HCC to sorafenib therapy and prolong survival by abrogating Mapk14-dependent activation of Mek-Erk and Atf2 signaling. Elevated Mapk14-Atf2 signaling predicted poor response to sorafenib therapy in human HCC, and sorafenib resistance of p-Mapk14-expressing HCC cells could be reverted by silencing Mapk14. Our results suggest that a combination of sorafenib and Mapk14 blockade is a promising approach to overcoming therapy resistance of human HCC.
To histologically evaluate the efficacy and nontarget effects induced by transarterial chemoembolization as a "bridge" treatment of hepatocellular carcinoma (HCC) before liver transplantation (LT) and its relation to patient survival.
New technical devices for hepatic parenchymal transection have improved perioperative safety and patient survival. The aim of the present study was to determine the oncological outcome after stapler hepatectomy in patients with HCC.
Hepatocarcinogenesis is a stepwise process. It involves several genetic and epigenetic alterations, e.g., loss of tumor suppressor gene expression (TP53, PTEN, RB) as well as activation of oncogenes (c-MYC, MET, BRAF, RAS). However, the role of RNA-binding proteins (RBPs), which regulate tumor suppressor and oncogene expression at the posttranscriptional level, are not well understood in hepatocellular carcinoma (HCC). Here we analyzed RBPs induced in human liver cancer, revealing 116 RBPs with a significant and more than 2-fold higher expression in HCC compared to normal liver tissue. We focused our subsequent analyses on the Insulin-like growth factor 2 messenger RNA (mRNA)-binding protein 1 (IGF2BP1) representing the most strongly up-regulated RBP in HCC in our cohort. Depletion of IGF2BP1 from multiple liver cancer cell lines inhibits proliferation and induces apoptosis in vitro. Accordingly, murine xenograft assays after stable depletion of IGF2BP1 reveal that tumor growth, but not tumor initiation, strongly depends on IGF2BP1 in vivo. At the molecular level, IGF2BP1 binds to and stabilizes the c-MYC and MKI67 mRNAs and increases c-Myc and Ki-67 protein expression, two potent regulators of cell proliferation and apoptosis. These substrates likely mediate the impact of IGF2BP1 in human liver cancer, but certainly additional target genes contribute to its function.
After allogeneic hematopoietic cell transplantation (alloHCT) liver biopsy is performed for enigmatic liver disorders when noninvasive diagnostic steps have failed in establishing a definitive diagnosis. This document provides an updated consensus on the prerequisites for proper evaluation of liver biopsies in alloHCT patients and the histological diagnostic criteria for liver graft-versus-host disease (GvHD). The Working Group's recommendations for the histological diagnosis of liver GvHD were derived from the peer-reviewed literature and from the consensus diagnosis of a total of 30 coded liver biopsies. Acceptance of the recommendations was tested by a survey distributed to all HCT centers in Austria, Germany and Switzerland. Consensus was achieved for biopsy indications, methods of sample acquisition and processing, reporting and interpretation of biopsy findings. As GvHD is variably treated and the treatment modalities have changed over time, the panel endorses the use of more frequent biopsies in clinical studies in order to improve the present challenging clinical and diagnostic situation.
The deubiquitinase CYLD removes (K-63)-linked polyubiquitin chains from proteins involved in NF-?B, Wnt/ß-catenin and Bcl-3 signaling. Reduced CYLD expression has been reported in different tumor entities, including hepatocellular carcinoma (HCC). Furthermore, loss of CYLD has been shown to contribute to HCC development in knockout animal models. This study aimed to assess subcellular CYLD expression in tumor tissues and its prognostic significance in HCC patients undergoing liver resection or liver transplantation.
The p53 tumor suppressor coordinates a series of antiproliferative responses that restrict the expansion of malignant cells, and as a consequence, p53 is lost or mutated in the majority of human cancers. Here, we show that p53 restricts expression of the stem and progenitor-cell-associated protein nestin in an Sp1/3 transcription-factor-dependent manner and that Nestin is required for tumor initiation in vivo. Moreover, loss of p53 facilitates dedifferentiation of mature hepatocytes into nestin-positive progenitor-like cells, which are poised to differentiate into hepatocellular carcinomas (HCCs) or cholangiocarcinomas (CCs) in response to lineage-specific mutations that target Wnt and Notch signaling, respectively. Many human HCCs and CCs show elevated nestin expression, which correlates with p53 loss of function and is associated with decreased patient survival. Therefore, transcriptional repression of Nestin by p53 restricts cellular plasticity and tumorigenesis in liver cancer.
The cyclin-dependent kinase inhibitor p21 has been implicated as a tumour suppressor. Moreover, recent genetic studies suggest that p21 might be a potential therapeutic target to improve regeneration in chronic diseases. The aim of this study was to delineate the role of p21 in chronic liver injury and to specify its role in hepatocarcinogenesis in a mouse model of chronic cholestatic liver injury.
Oncogene-induced senescence (OIS) is crucial for tumour suppression. Senescent cells implement a complex pro-inflammatory response termed the senescence-associated secretory phenotype (SASP). The SASP reinforces senescence, activates immune surveillance and paradoxically also has pro-tumorigenic properties. Here, we present evidence that the SASP can also induce paracrine senescence in normal cells both in culture and in human and mouse models of OIS in vivo. Coupling quantitative proteomics with small-molecule screens, we identified multiple SASP components mediating paracrine senescence, including TGF-? family ligands, VEGF, CCL2 and CCL20. Amongst them, TGF-? ligands play a major role by regulating p15(INK4b) and p21(CIP1). Expression of the SASP is controlled by inflammasome-mediated IL-1 signalling. The inflammasome and IL-1 signalling are activated in senescent cells and IL-1? expression can reproduce SASP activation, resulting in senescence. Our results demonstrate that the SASP can cause paracrine senescence and impact on tumour suppression and senescence in vivo.
Complete surgical tumor resection (R0) for treatment of intrahepatic cholangiocarcinoma (ICC) is potentially curative, but the prognosis remains dismal due to frequent tumor recurrence and metastasis after surgery. Adjuvant therapies may improve the outcome, but clinical studies for an adjuvant approach are difficult and time-consuming for rare tumor entities. Therefore, animal models reflecting the clinical situation are urgently needed to investigate novel adjuvant therapies. To establish a mouse model of resectable cholangiocarcinoma including the most frequent genetic alterations of human ICC, we electroporated Sleeping Beauty-based oncogenic transposon plasmids into the left liver lobe of mice. KRas-activation in combination with p53-knockout in hepatocytes resulted in formation of a single ICC nodule within 3-5 weeks. Lineage tracing analyses confirmed the development of ICC by transdifferentiation of hepatocytes. Histologic examination demonstrated that no extrahepatic metastases were detectable during primary tumor progression. However, formation of tumor satellites close to the primary tumor and vascular invasion were observed, indicating early invasion into normal tissue adjacent to the tumor. After R0-resection of the primary tumor, we were able to prolong median survival, thereby observing tumor stage-dependent local recurrence, peritoneal carcinomatosis, and lung metastasis. Adjuvant gemcitabine chemotherapy after R0-resection significantly improved median survival of treated animals. Conclusion: We have developed a murine model of single, R0-resectable ICC with favorable characteristics for the study of recurrence patterns and mechanisms of metastasis after resection. This model holds great promise for preclinical evaluation of novel multimodal or adjuvant therapies to prevent recurrence and metastasis after R0-resection.
Focal nodular hyperplasia (FNH) and hepatocellular adenoma (HCA) are benign hepatocellular tumors. The risk of bleeding and malignant transformation of HCA are strong arguments to differentiate HCA from FNH. Despite great progress that has been made in the differential radiological diagnosis of the 2 types of nodules, liver biopsy is sometimes necessary to separate the 2 entities. Identification of HCA subtypes using immunohistochemical techniques, namely, HNF1A-inactivated HCA (35-40%), inflammatory HCA (IHCA), and beta-catenin-mutated inflammatory HCA (b-IHCA) (50-55%), beta-catenin-activated HCA (5-10%), and unclassified HCA (10%) has greatly improved the diagnostic accuracy of benign hepatocellular nodules. If HCA malignant transformation occurs in all HCA subgroups, the risk is by far the highest in the ? -catenin-mutated subgroups (b-HCA, b-IHCA). In the coming decade the management of HCA will be more dependent on the identification of HCA subtypes, particularly for smaller nodules (<5?cm) in terms of imaging, follow-up, and resection.
The liver harbors a distinct capacity for endogenous regeneration; however, liver regeneration is often impaired in disease and therefore insufficient to compensate for the loss of hepatocytes and organ function. Here we describe a functional genetic approach for the identification of gene targets that can be exploited to increase the regenerative capacity of hepatocytes. Pools of small hairpin RNAs (shRNAs) were directly and stably delivered into mouse livers to screen for genes modulating liver regeneration. Our studies identify the dual-specific kinase MKK4 as a master regulator of liver regeneration. MKK4 silencing robustly increased the regenerative capacity of hepatocytes in mouse models of liver regeneration and acute and chronic liver failure. Mechanistically, induction of MKK7 and a JNK1-dependent activation of the AP1 transcription factor ATF2 and the Ets factor ELK1 are crucial for increased regeneration of hepatocytes with MKK4 silencing.
The receptor for advanced glycation endproducts (RAGE) is a multiligand receptor and member of the immunoglobulin superfamily. RAGE is mainly involved in tissue damage and chronic inflammatory disorders, sustaining the inflammatory response upon engagement with damage-associated molecular pattern molecules (DAMPs) such as S100 proteins and high-mobility group box 1 (HMGB1). Enhanced expression of RAGE and its ligands has been demonstrated in distinct tumors and several studies support its crucial role in tumor progression and metastasis by still unknown mechanisms. Here we show that RAGE supports hepatocellular carcinoma (HCC) formation in the Mdr2(-/-) mouse model, a prototype model of inflammation-driven HCC formation, which mimics the human pathology. Mdr2(-/-) Rage(-/-) (dKO) mice developed smaller and fewer HCCs than Mdr2(-/-) mice. Interestingly, although in preneoplastic Mdr2(-/-) livers RAGE ablation did not affect the onset of inflammation, premalignant dKO livers showed reduced liver damage and fibrosis, in association with decreased oval cell activation. Oval cells expressed high RAGE levels and displayed reduced proliferation upon RAGE silencing. Moreover, stimulation of oval cells with HMGB1 promoted an ERK1/2-Cyclin D1-dependent oval cell proliferation in vitro. Finally, genetic and pharmacologic blockade of RAGE signaling impaired oval cell activation in an independent mouse model of oval cell activation, the choline deficient ethionine-supplemented dietary regime. Conclusion: Our data identified a novel function of RAGE in regulating oval cell activation and tumor development in inflammation-associated liver carcinogenesis.
Hepatocellular carcinoma (HCC) is a malignant tumour that is characterized by extensive vascular remodelling and responsiveness to treatment with the anti-angiogenic multikinase inhibitor sorafenib. The aim was to study endothelial remodelling in HCC.
Hepatocellular carcinoma (HCC) frequently arises in the context of chronic injury that promotes DNA damage and chromosomal aberrations. The cyclin-dependent kinase inhibitor p21 is an important transcriptional target of several tumor suppressors, which promotes cell cycle arrest in response to many stimuli. The aim of this study was to further delineate the role of p21 in the liver during moderate and severe injury and to specify its role in the initiation and progression of HCC. Deletion of p21 led to continuous hepatocyte proliferation in mice with severe injury allowing animal survival but also facilitated rapid tumor development, suggesting that control of compensatory proliferation by high levels of p21 is critical to the prevention of tumor development. Unexpectedly, however, liver regeneration and hepatocarcinogenesis was impaired in p21-deficient mice with moderate injury. Mechanistically, loss of p21 was compensated by activation of Sestrin2, which impaired mitogenic mammalian target of rapamycin (mTOR) signaling and activated cytoprotective Nrf2 signaling. Conclusion: The degree of liver injury and the strength of p21 activation determine its effects on liver regeneration and tumor development in the liver. Moreover, our data uncover a molecular link in the complex mTOR, Nrf2, and p53/p21-signaling network through activation of Sestrin2, which regulates hepatocyte proliferation and tumor development in mice with liver injury.
Selected long noncoding RNAs (lncRNAs) have been shown to play important roles in carcinogenesis. Although the cellular functions of these transcripts can be diverse, many lncRNAs regulate gene expression. In contrast, factors that control the expression of lncRNAs remain largely unknown. Here we investigated the impact of RNA binding proteins on the expression of the liver cancer-associated lncRNA HULC (highly up-regulated in liver cancer). First, we validated the strong up-regulation of HULC in human hepatocellular carcinoma. To elucidate posttranscriptional regulatory mechanisms governing HULC expression, we applied an RNA affinity purification approach to identify specific protein interaction partners and potential regulators. This method identified the family of IGF2BPs (IGF2 mRNA-binding proteins) as specific binding partners of HULC. Depletion of IGF2BP1, also known as IMP1, but not of IGF2BP2 or IGF2BP3, led to an increased HULC half-life and higher steady-state expression levels, indicating a posttranscriptional regulatory mechanism. Importantly, HULC represents the first IGF2BP substrate that is destabilized. To elucidate the mechanism by which IGF2BP1 destabilizes HULC, the CNOT1 protein was identified as a novel interaction partner of IGF2BP1. CNOT1 is the scaffold of the human CCR4-NOT deadenylase complex, a major component of the cytoplasmic RNA decay machinery. Indeed, depletion of CNOT1 increased HULC half-life and expression. Thus, IGF2BP1 acts as an adaptor protein that recruits the CCR4-NOT complex and thereby initiates the degradation of the lncRNA HULC. Conclusion: Our findings provide important insights into the regulation of lncRNA expression and identify a novel function for IGF2BP1 in RNA metabolism. (Hepatology 2013).
Recent evidence suggests an involvement of the tyrosine kinase signaling pathway in the development of ATP-binding cassette (ABC) protein-mediated multidrug resistance in cancer. The aim of our study was to determine the relevance of kinase and multidrug-resistance protein expression in human hepatocellular carcinoma (HCC).
Microdialysis (MD) can detect organ-related metabolic changes before they become measurable in plasma through the biochemical parameters. This study aims to evaluate the early detection of metabolic changes during experimental kidney transplantation (KTx).
Upon the aberrant activation of oncogenes, normal cells can enter the cellular senescence program, a state of stable cell-cycle arrest, which represents an important barrier against tumour development in vivo. Senescent cells communicate with their environment by secreting various cytokines and growth factors, and it was reported that this secretory phenotype can have pro- as well as anti-tumorigenic effects. Here we show that oncogene-induced senescence occurs in otherwise normal murine hepatocytes in vivo. Pre-malignant senescent hepatocytes secrete chemo- and cytokines and are subject to immune-mediated clearance (designated as senescence surveillance), which depends on an intact CD4(+) T-cell-mediated adaptive immune response. Impaired immune surveillance of pre-malignant senescent hepatocytes results in the development of murine hepatocellular carcinomas (HCCs), thus showing that senescence surveillance is important for tumour suppression in vivo. In accordance with these observations, ras-specific Th1 lymphocytes could be detected in mice, in which oncogene-induced senescence had been triggered by hepatic expression of Nras(G12V). We also found that CD4(+) T cells require monocytes/macrophages to execute the clearance of senescent hepatocytes. Our study indicates that senescence surveillance represents an important extrinsic component of the senescence anti-tumour barrier, and illustrates how the cellular senescence program is involved in tumour immune surveillance by mounting specific immune responses against antigens expressed in pre-malignant senescent cells.
In biomedical research, a variety of data like clinical, genetic, expression of coding or non-coding ribonucleic acid (RNA) transcripts, or proteomic data are processed to gain new insights into diseases and therapies. In transregional research networks, geographically distributed projects work on comparable research questions with data from different resources and in different formats. Providing an information platform that integrates the data of the projects can enable cross-project analysis and provides an overview of available data and resources (tissue, blood, etc.). For a German liver cancer research network consisting of 22 individual projects, we develop the integrated information platform pelican - platform enhancing liver cancer networked research. In our generic approach, data are made available to the research network by standardized data services based on technologies provided by the cancer Biomedical Informatics Grid (caBIG). It has shown that publishing service metadata in a corresponding repository is a major prerequisite for automated discovery, integration, and conversion of data records and data services. We identified data confidentiality and intellectual property considerations as major challenges while establishing such an integrated information platform. As a first result we implemented a working prototype to validate our approach.
In kidney transplantation (KTx), vascular thrombosis has a major impact on morbidity and graft survival. The ischaemia, caused by thrombosis, can lead to interstitial metabolite changes. The aim of this experimental study was to create conditions in which the graft would be prone to vascular thrombosis following KTx and then to evaluate the role of microdialysis (MD) for its early detection.
Matrix metalloproteinase-9 (MMP-9) plays a central role in tumor invasion and development of metastases. Expression of MMP-9 had been shown in human hepatocellular carcinomas (HCCs). However, it remained unclear whether MMP-9 could influence development of HCC. In order to address this issue, we generated transgenic mice overexpressing MMP-9 in the liver. In order to avoid embryonic lethality a Cre-lox system was utilized for conditional overexpression of MMP-9 under control of an albumin enhancer and promoter. Induction of MMP-9 overexpression in transgenic mice was achieved by i.v. injection of an adenovirus coding for the Cre recombinase. Initiation of liver carcinogenesis was achieved by injection of diethylnitrosamine (DEN) followed by Phenobarbital administration in drinking water. Transgene expression was induced at the age of 6 wk. Four and six months later mice were sacrificed and examined macroscopically and microscopically in a blinded manner. Alb/Cre/MMP-9-transgenic mice showed liver specific overexpression of MMP-9-mRNA and protein after induction. At the age of 6 months livers of transgenic mice showed 15.7 ± 11.6 tumors (mean ± SD) in contrast to wildtype mice with only 7.9 ± 11.0 tumors (P < 0.03). By histopathology examination of the livers HCCs were identified in 42% of the transgenic mouse livers but only 8% in wildtype animals. In summary, we established a novel MMP-9 transgenic mouse model, and report on a significantly increased susceptibility of MMP-9 transgenic mice to chemically induced carcinogenesis. This is the first in vivo proof that MMP-9 overexpression promotes liver tumor development.
Classical comparative genomic hybridization (CGH) has been used to identify recurrent genomic alterations in human HCC. As hepatocarcinogenesis is considered as a stepwise process, we applied oncogenetic tree modeling on all available classical CGH data to determine occurrence of genetic alterations over time. Nine losses (1p, 4q, 6q, 8p, 9p, 13q, 16p, 16q and 17p) and ten gains (1q, 5p, 6p, 7p, 7q, 8q, 17q, 20p, 20q and Xq) of genomic information were used to build the oncogenetic tree model. Whereas gains of 1q and 8q together with losses of 8p formed a cluster that represents early etiology-independent alterations, the associations of gains at 6q and 17q as well as losses of 6p and 9p were observed during tumor progression. HBV-induced HCCs had significantly more chromosomal aberrations compared to HBV-negative tumors. Losses of 1p, 4q and 13q were associated with HBV-induced HCCs, whereas virus-negative HCCs showed an association of gains at 5p, 7, 20q and Xq. Using five aberrations that were significantly associated with tumor dedifferentiation a robust progression model of stepwise human hepatocarcinogensis (gain 1q ? gain 8q ? loss 4q ? loss 16q ? loss 13q) was developed. In silico analysis revealed that protumorigenic candidate genes have been identified for each recurrently altered hotspot. Thus, oncogenic candidate genes that are coded on chromosome arms 1q and 8q are promising targets for the prevention of malignant transformation and the development of biomarkers for the early diagnosis of human HCC that may significantly improve the treatment options and thus prognosis of HCC patients.
Hepatitis C virus (HCV) is a major causative agent of chronic liver disease in humans. To gain insight into host factor requirements for HCV replication, we performed a siRNA screen of the human kinome and identified 13 different kinases, including phosphatidylinositol-4 kinase III alpha (PI4KIII?), as being required for HCV replication. Consistent with elevated levels of the PI4KIII? product phosphatidylinositol-4-phosphate (PI4P) detected in HCV-infected cultured hepatocytes and liver tissue from chronic hepatitis C patients, the enzymatic activity of PI4KIII? was critical for HCV replication. Viral nonstructural protein 5A (NS5A) was found to interact with PI4KIII? and stimulate its kinase activity. The absence of PI4KIII? activity induced a dramatic change in the ultrastructural morphology of the membranous HCV replication complex. Our analysis suggests that the direct activation of a lipid kinase by HCV NS5A contributes critically to the integrity of the membranous viral replication complex.
Differential expression of tumor-relevant proteins based on aberrant proteasomal degradation may contribute to human (hepato)carcinogenesis. Recently, we identified the E3 ubiquitin ligase seven in absentia homolog (SIAH)-1 as frequently dysregulated in human hepatocellular carcinoma (HCC). We therefore systematically analyzed the expression, functional relevance, as well as possible downstream effectors of SIAH-1 in human liver carcinogenesis.
Systemic iron homeostasis is mainly controlled by the liver through synthesis of the peptide hormone hepcidin (encoded by Hamp), the key regulator of duodenal iron absorption and macrophage iron release. Here we show that the liver-specific microRNA miR-122 is important for regulating Hamp mRNA expression and tissue iron levels. Efficient and specific depletion of miR-122 by injection of a locked-nucleic-acid-modified (LNA-modified) anti-miR into WT mice caused systemic iron deficiency, characterized by reduced plasma and liver iron levels, mildly impaired hematopoiesis, and increased extramedullary erythropoiesis in the spleen. Moreover, miR-122 inhibition increased the amount of mRNA transcribed by genes that control systemic iron levels, such as hemochromatosis (Hfe), hemojuvelin (Hjv), bone morphogenetic protein receptor type 1A (Bmpr1a), and Hamp. Importantly, miR-122 directly targeted the 3? untranslated region of 2 mRNAs that encode activators of hepcidin expression, Hfe and Hjv. These data help to explain the increased Hamp mRNA levels and subsequent iron deficiency in mice with reduced miR-122 levels and establish a direct mechanistic link between miR-122 and the regulation of systemic iron metabolism.
While improved imaging techniques have made it possible to detect focal liver lesions smaller than 1cm in diameter, differentiating benign lesions from hepatocellular carcinoma (HCC) still remains a challenge. To address this problem and obtain a definite diagnosis, needle core biopsies are often performed, leading to an increased need for supportive ancillary techniques in the histopathological assessment of highly differentiated hepatocellular tumors. Here we evaluate the diagnostic value of immunohistologically detected Annexin A2 (ANXA2) expression in highly differentiated liver tumors. ANXA2 is a calcium-dependent phospholipid-binding protein that has been linked to malignant transformation and HCC development. Our data show that adding sinusoidal ANXA2 expression to the already established marker panel (GPC3, GS, and HSP70) increases the accuracy for the detection of well-differentiated HCC (74% sensitivity, 100% specificity). In addition, in our series, the combinations ANXA2-GPC3 and ANXA2-GS performed better compared to the other established marker combinations. In conclusion, we suggest that adding ANXA2 to the established diagnostic marker panel increases the reliability and objectivity of HCC diagnosis in liver biopsies.
Hepatotoxic side effects of neoadjuvant chemotherapy for colorectal liver metastases increase perioperative morbidity and mortality. Glycine protects liver from injury in various animal models. Thus, this study was designed to assess its effect on liver after chemotherapy. Sprague-Dawley rats (200-220 g) were fed a synthetic diet containing 5% glycine for 5 days. Subsequently, chemotherapy (FOLFIRI: irinotecan, folinic acid and fluorouracil, or FOLFOX: oxaliplatin, folinic acid and fluorouracil) was administered at standard doses. Transaminases, histology, immunohistochemistry and in vivo microscopy were used to index liver injury, to monitor intrahepatic microperfusion and activation of Kupffer cells. Glycine significantly decreased transaminases after chemotherapy to 25-50% of control values (p < 0.05). Microvesicular steatosis was significantly reduced from 18.5 ± 3.4 and 57.1 ± 8.6% in controls to 9.5 ± 1.8 and 37.7 ± 4.4% after FOLFIRI and FOLFOX, respectively. Furthermore, phagocytosis of latex beads was reduced by about 50%, while leukocyte adherence in central and midzonal subacinar zones decreased to 60-80% after glycine (p < 0.05). Glycine significantly reduced expression of inducible nitric oxide synthase after chemotherapy, while hepatic microcirculation was increased (p < 0.05). This study shows for the first time that glycine reduces chemotherapy-induced liver injury. The underlying mechanisms most likely include Kupffer cells and an improved intrahepatic microperfusion.
The A kinase anchor protein 12 (AKAP12) is a central mediator of protein kinase A and protein kinase C signaling. Although AKAP12 has been described to act as a tumor suppressor and its expression is frequently down-regulated in several human malignancies, the underlying molecular mechanisms responsible for the AKAP12 reduction are poorly understood. We therefore analyzed the expression of AKAP12 and its genetic and epigenetic regulatory mechanisms in human hepatocarcinogenesis. Based on tissue microarray analyses (n = 388) and western immunoblotting, we observed a significant reduction of AKAP12 in cirrhotic liver (CL), premalignant lesions (DN), and hepatocellular carcinomas (HCCs) compared to histologically normal liver specimens (NL). Analyses of array comparative genomic hybridization data (aCGH) from human HCCs revealed chromosomal losses of AKAP12 in 36% of cases but suggested additional mechanisms underlying the observed reduction of AKAP12 expression in hepatocarcinogenesis. Quantitative methylation analysis by MassARRAY of NL, CL, DN, and HCC tissues, as well as of various tumorigenic and nontumorigenic liver cell lines revealed specific hypermethylation of the AKAP12? promoter but not of the AKAP12? promoter in HCC specimens and in HCC cell lines. Consequently, restoration experiments performed with 5-aza-2deoxycytidine drastically increased AKAP12? mRNA levels in a HCC cell line (AKN1) paralleled by AKAP12? promoter demethylation. As hypermethylation is not observed in CL and DN, we investigated microRNA-mediated posttranscriptional regulation as an additional mechanism to explain reduced AKAP12 expression. We found that miR-183 and miR-186 are up-regulated in CL and DN and are able to target AKAP12. Conclusion: In addition to genetic alterations, epigenetic mechanisms are responsible for the reduction of the tumor suppressor gene AKAP12 in human hepatocarcinogenesis.
To test if inflammation also interferes with liver stiffness (LS) assessment in alcoholic liver disease (ALD) and to provide a clinical algorithm for reliable fibrosis assessment in ALD by FibroScan (FS).
Polo-like kinase (PLK) proteins play critical roles in the control of cell cycle progression, either favoring or inhibiting cell proliferation, and in DNA damage response. Although either overexpression or down-regulation of PLK proteins occurs frequently in various cancer types, no comprehensive analysis on their function in human hepatocellular carcinoma (HCC) has been performed to date. In the present study, we define roles for PLK1, PLK2, PLK3, and PLK4 during hepatocarcinogenesis. Levels of PLK1, as assessed by means of real-time reverse-transcription PCR and western blot analysis, were progressively increased from nonneoplastic surrounding liver tissues to HCC, reaching the highest expression in tumors with poorer outcome (as defined by the length of patients survival) compared with normal livers. In sharp contrast, PLK2, PLK3, and PLK4 messenger RNA and protein expression gradually declined from nontumorous liver to HCC, with the lowest levels being detected in HCC with shorter survival. In liver tumors, PLK2-4 down-regulation was paralleled by promoter hypermethylation and/or loss of heterozygosity at the PLK2-4 loci. Subsequent functional studies revealed that PLK1 inhibition led to suppression of cell growth in vitro, whereas opposite effects followed PLK2-4 silencing in HCC cell lines. In particular, suppression of PLK1 resulted in a block in the G2/M phase of the cell cycle and in massive apoptosis of HCC cells in vitro regardless of p53 status. Conclusion: PLK1-4 proteins are aberrantly regulated and possess different roles in human HCC, with PLK1 acting as an oncogene and PLK2-4 being presumably tumor suppressor genes. Thus, therapeutic approaches aimed at inactivating PLK1 and/or reactivating PLK2-4 might be highly useful in the treatment of human liver cancer.
In many human cancers, lipogenic pathways are activated; in some tumors, such as hepatocellular carcinoma, this is reflected by the presence of visible lipid droplets. Yet, the biology of steatogenesis in malignant tumors is largely unknown. We have recently shown that lipid droplet-associated proteins of the PAT-family, named after their constituents perilipin (perilipin 1), adipophilin (perilipin 2), and TIP47 (perilipin 3) are differentially expressed in hepatic steatogenesis. We have comprehensively investigated PAT-expression in neoplastic steatogenesis as well as in respective normal tissues with immunohistology and electron microscopy as well as protein biochemical and molecular biological methods. By staining for PAT-proteins, we found lipid droplet accumulation to be a frequent phenomenon of carcinoma cells. Although adipophilin and TIP47 stained almost ubiquitously the rim of lipid droplets in various tumor types, especially those with clear cell phenotype, perilipin was restricted to lipid droplets of hepatocellular adenoma and carcinoma, sebaceous adenoma and carcinoma, and lipomatous tumors. In hepatocellular carcinoma, perilipin, adipophilin, and TIP47 were coexpressed, and showed regional heterogeneity with a predominantly mutually exclusive localization pattern. In step-wise carcinogenesis, adipophilin expression correlated with the proliferation rate and was upregulated during early tumorigenesis, whereas perilipin was often lost during hepatocarcinogenesis. In conclusion, expression analysis of PAT-proteins showed that by far more carcinomas contain (PAT-positive) lipid droplets than expected by conventional light microscopy. PAT-proteins, such as perilipin, are differentially expressed in different tumor types and thus may support diagnostic considerations. Because inhibition of lipogenesis has been shown to exert antineoplastic effects, PAT-proteins may represent targets for interventive strategies.
The nuclear factor-kappaB (NF-kappaB) signaling pathway has been recently shown to participate in inflammation-induced cancer progression. Here, we describe a detailed analysis of the NF-kappaB-dependent gene regulatory network in the well-established Mdr2 knockout mouse model of inflammation-associated liver carcinogenesis. Expression profiling of NF-kappaB-deficient and NF-kappaB-proficient hepatocellular carcinoma (HCC) revealed a comprehensive list of known and novel putative NF-kappaB target genes, including S100a8 and S100a9. We detected increased co-expression of S100A8 and S100A9 proteins in mouse HCC cells, in human HCC tissue, and in the HCC cell line Hep3B on ectopic RelA expression. Finally, we found a synergistic function for S100A8 and S100A9 in Hep3B cells resulting in a significant induction of reactive oxygen species (ROS), accompanied by enhanced cell survival.
Microtubule-dependent effects are partly regulated by factors that coordinate polymer dynamics such as the microtubule-destabilizing protein stathmin (oncoprotein 18). In cancer cells, increased microtubule turnover affects cell morphology and cellular processes that rely on microtubule dynamics such as mitosis and migration. However, the molecular mechanisms deregulating modifiers of microtubule activity in human hepatocarcinogenesis are poorly understood. Based on profiling data of human hepatocellular carcinoma (HCC), we identified far upstream element binding proteins (FBPs) as significantly coregulated with stathmin. Coordinated overexpression of two FBP family members (FBP-1 and FBP-2) in >70% of all analyzed human HCCs significantly correlated with poor patient survival. In vitro, FBP-1 predominantly induced tumor cell proliferation, while FBP-2 primarily supported migration in different HCC cell lines. Surprisingly, reduction of FBP-2 levels was associated with elevated FBP-1 expression, suggesting a regulatory interplay of FBP family members that functionally discriminate between cell division and mobility. Expression of FBP-1 correlated with stathmin expression in HCC tissues and inhibition of FBP-1 but not of FBP-2 drastically reduced stathmin at the transcript and protein levels. In contrast, further overexpression of FBP-1 did not affect stathmin bioavailability. Accordingly, analyzing nuclear and cytoplasmic areas of HCC cells revealed that reduced FBP-1 levels affected cell morphology and were associated with a less malignant phenotype.
Systemic complications including pancreatitis-associated lung injury (PALI) are critical factors that determine the outcome of severe necrotizing pancreatitis (SNP). The aim of the present study was to evaluate the role of chronic alcohol exposure on the development of PALI.
Pancreatic ductal adenocarcinoma (PDAC) is frequently associated with fibrosis and a prominent inflammatory infiltrate in the desmoplastic stroma. Moreover, in PDAC, an epithelial-to-mesenchymal transition (EMT) is observed. To explore a possible connection between the infiltrating cells, particularly the polymorphonuclear neutrophils (PMN) and the tumor cell transition, biopsies of patients with PDAC (n = 115) were analysed with regard to PMN infiltration and nuclear expression of ?-catenin and of ZEB1, well-established indicators of EMT. In biopsies with a dense PMN infiltrate, a nuclear accumulation of ?-catenin and of ZEB1 was observed. To address the question whether PMN could induce EMT, they were isolated from healthy donors and were cocultivated with pancreatic tumor cells grown as monolayers. Rapid dyshesion of the tumor cells was seen, most likely due to an elastase-mediated degradation of E-cadherin. In parallel, the transcription factor TWIST was upregulated, ?-catenin translocated into the nucleus, ZEB1 appeared in the nucleus, and keratins were downregulated. EMT was also induced when the tumor cells were grown under conditions preventing attachment to the culture plates. Here, also in the absence of elastase, E-cadherin was downmodulated. PMN as well as prevention of adhesion induced EMT also in liver cancer cell line. In conclusion, PMN via elastase induce EMT in vitro, most likely due to the loss of cell-to-cell contact. Because in pancreatic cancers the transition to a mesenchymal phenotype coincides with the PMN infiltrate, a contribution of the inflammatory response to the induction of EMT and-by implication-to tumor progression is possible.
The p53 tumor suppressor utilizes multiple mechanisms to selectively regulate its myriad target genes, which in turn mediate diverse cellular processes. Here, using conventional and single-molecule mRNA analyses, we demonstrate that the nucleoporin Nup98 is required for full expression of p21, a key effector of the p53 pathway, but not several other p53 target genes. Nup98 regulates p21 mRNA levels by a posttranscriptional mechanism in which a complex containing Nup98 and the p21 mRNA 3UTR protects p21 mRNA from degradation by the exosome. An in silico approach revealed another p53 target (14-3-3?) to be similarly regulated by Nup98. The expression of Nup98 is reduced in murine and human hepatocellular carcinomas (HCCs) and correlates with p21 expression in HCC patients. Our study elucidates a previously unrecognized function of wild-type Nup98 in regulating select p53 target genes that is distinct from the well-characterized oncogenic properties of Nup98 fusion proteins.
Flat epithelial atypia (FEA) of the breast typically is a localized alteration involving only few, neighboring terminal ducto-lobular units. However, occasionally there are cases with extensive FEA and morphologic evidence of direct transitions between FEA and classical low-grade ductal carcinoma in situ (lg-DCIS). To investigate the relationship between FEA and DCIS in these cases, we microdissected multiple foci of the respective lesions in a series of 10 cases and performed comparative allelotyping using a panel of 14 loss of heterozygosity markers. In addition, phylogenetic tree models were calculated on the basis of mitochondrial DNA sequencing to visualize the clonal relationship of the different lesions. FEA and lg-DCIS shared the majority of chromosomal imbalances; loss of diverging alleles was not detected in any of the 10 cases. Mitochondrial DNA sequencing and phylogenetic tree clustering revealed direct transitions between FEA and lg-DCIS in all 10 cases. However, in 3 patients, additional foci of FEA were present, which were not directly related to the rest of the FEA and the lg-DCIS. Our data demonstrate the presence of direct transitions between FEA and lg-DCIS and support the interpretation of FEA as part of the low-grade pathway in the development of breast cancer.
Highly promising preclinical data obtained in cultured cells and in nude mice bearing xenografts contrast with the rather modest clinical efficacy of Polo-like kinase 1 (Plk1) inhibitors. In the present study, we investigated if Plk1 might be a suitable target in hepatocellular carcinoma (HCC) and if a genetically engineered mouse tumor model that well reflects the tumor cell and micro-environmental features of naturally occurring cancers might be suitable to study anti-Plk1 therapy. Analysis of Plk1 expression in human HCC samples confirmed that HCC express much higher Plk1 levels than the adjacent normal liver tissue. Inhibition of Plk1 by an adenovirus encoding for a short hairpin RNA against Plk1 or by the small-molecule inhibitor BI 2536 reduced the viability of HCC cell lines and inhibited HCC xenograft progression in nude mice. Treatment of transforming growth factor (TGF) ?/c-myc bitransgenic mice with BI 2536 during hepatocarcinogenesis reduced the number of dysplastic foci and of Ki-67-positive cells within the foci, indicating diminished tumorigenesis. In contrast, BI 2536 had no significant effect on HCC progression in the transgenic mouse HCC model as revealed by magnetic resonance imaging. Measurement of BI 2536 by mass spectrometry revealed considerably lower BI 2536 levels in HCC compared with the adjacent normal liver tissue. In conclusion, low intratumoral levels are a novel mechanism of resistance to the Plk1 inhibitor BI 2536. Plk1 inhibitors achieving sufficient intratumoral levels are highly promising in HCC treatment.
CYLD is a tumor suppressor gene that is mutated in familial cylindromatosis, an autosomal dominant predisposition to tumors of skin appendages. Reduced CYLD expression has been observed in other tumor entities, including hepatocellular carcinoma. In the present study, we analyzed the role of CYLD in liver homeostasis and hepatocarcinogenesis in vivo.
Chronic liver disease promotes hepatocellular injury involving apoptosis and triggers compensatory regeneration that leads to the activation of quiescent stellate cells in the liver. The deposition of extracellular matrix from activated myofibroblasts promotes hepatic fibrosis and the progression to cirrhosis with deleterious effects on liver physiology. The role of apoptosis signaling pathways in the development of fibrosis remains undefined. The aim of the current study was to determine the involvement of the caspase-8 homologue cellular FLICE-inhibitory protein (cFLIP) during the initiation and progression of fibrosis. Liver injury and fibrosis from carbon tetrachloride (CCl(4)) and thioacetamide (TAA) were examined in mice exhibiting a hepatocyte-specific deletion of cFLIP (flip(-/-)). Acute liver injury from CCl(4) and TAA were enhanced in flip(-/-) mice. This was accompanied by increased activation of caspase-3 and -9, pronounced phosphorylation of JNK, and decreased phosphorylation of Erk. Deletion of the cJun NH(2)-terminal kinase 2 (JNK2) in flip(-/-) mice protected from injury. Hepatic fibrosis was increased at baseline in 12-wk-old flip(-/-) mice, and progression of fibrosis from TAA was accelerated compared with the wild type. In conclusion, deletion of cFLIP in hepatocytes leads to increased fibrosis and accelerated fibrosis progression. This is accompanied by increased injury involving the activation of caspases and JNK2. Thus predisposition to liver injury involving increased hepatocellular apoptosis is a critical mediator of accelerated fibrogenesis, and prevention of liver injury will be a most important measure for patients with chronic liver disease.
Steroid-refractory graft-versus-host disease causes significant morbidity and mortality after allogeneic stem cell transplantation. The pathomechanism of steroid resistance is currently not understood, but it has been suggested that endothelial cell dysfunction plays a role. Endothelial thrombomodulin was quantified along with histological markers of epithelial damage and cytotoxic T cells in colon biopsies from 51 allografted patients, and retrospectively correlated with response to steroids and survival. Loss of endothelial thrombomodulin was the strongest predictor of response to steroids (P=0.02) and nonrelapse mortality (P=0.01) in multivariate analyses adjusting for T-cell infiltrates, histological grading, vessel density, disease status, donor type, and conditioning therapy. Our data provide evidence that at disease onset, loss of endothelial thrombomodulin expression rather than excessive T-cell infiltration associates with steroid-refractory graft-versus-host disease and mortality. Prospective histological investigations are now warranted to improve diagnosis and prognostication of this core complication of stem cell transplantation.
To identify new tumor-suppressor gene candidates relevant for human hepatocarcinogenesis, we performed genome-wide methylation profiling and vertical integration with array-based comparative genomic hybridization (aCGH), as well as expression data from a cohort of well-characterized human hepatocellular carcinomas (HCCs). Bisulfite-converted DNAs from 63 HCCs and 10 healthy control livers were analyzed for the methylation status of more than 14,000 genes. After defining the differentially methylated genes in HCCs, we integrated their DNA copy-number alterations as determined by aCGH data and correlated them with gene expression to identify genes potentially silenced by promoter hypermethylation. Aberrant methylation of candidates was further confirmed by pyrosequencing, and methylation dependency of silencing was determined by 5-aza-2-deoxycytidine (5-aza-dC) treatment. Methylation profiling revealed 2,226 CpG sites that showed methylation differences between healthy control livers and HCCs. Of these, 537 CpG sites were hypermethylated in the tumor DNA, whereas 1,689 sites showed promoter hypomethylation. The hypermethylated set was enriched for genes known to be inactivated by the polycomb repressive complex 2, whereas the group of hypomethylated genes was enriched for imprinted genes. We identified three genes matching all of our selection criteria for a tumor-suppressor gene (period homolog 3 [PER3], insulin-like growth-factor-binding protein, acid labile subunit [IGFALS], and protein Z). PER3 was down-regulated in human HCCs, compared to peritumorous and healthy liver tissues. 5-aza-dC treatment restored PER3 expression in HCC cell lines, indicating that promoter hypermethylation was indeed responsible for gene silencing. Additionally, functional analysis supported a tumor-suppressive function for PER3 and IGFALS in vitro.
Stability of many tumor-relevant proteins is partly mediated by E3 ligases, which determine substrate specificity within the ubiquitin system. Recent data demonstrated that increased nuclear expression of the E3 ligase seven in absentia homologue (SIAH)-1 in human hepatocarcinogenesis supports tumor cell proliferation and migration. To define whether closely related SIAH-2 synergizes with protumorigenic SIAH-1, we systematically analyzed expression, localization and functional relevance of SIAH-2 in human hepatocellular carcinoma (HCC). Nuclear accumulation of SIAH-2 is detectable in more than 60% of all HCCs and correlates with tumor progression, cell proliferation and distant metastasis. An inverse correlation between nuclear SIAH-1 and SIAH-2 was detected, suggesting independent mechanisms for nuclear enrichment. Inhibition of nuclear SIAH-2 by RNAi in HCC cell lines reduced proliferation as well as lateral tumor cell motility and transmigration; however, combined knock down of both SIAH-1 and SIAH-2 did not further amplify biological effects compared to single gene inhibition. Reduction of SIAH-2 expression sensitizes HCC cells to the treatment with different cytostatic drugs, demonstrating that SIAH-2-targeting approaches may increase the response of HCC cells to conventional chemotherapy. Together, these data show that SIAH-2--as described for SIAH-1--accumulates in nuclei of HCC cells where it supports tumor growth and tumor cell dissemination. Because the nuclear pattern of SIAH-2 differs in HCC tissues from the SIAH-1 pattern and because the inactivation of SIAH-2 is not compensated by SIAH-1, the specific inhibition of SIAH-2 (especially in combination with other drugs) represents a promising therapeutic strategy for HCC.
Giant cell hepatitis is a well-known histological feature of several neonatal and infantile liver diseases. In contrast, postinfantile giant cell hepatitis is rarely identified in adult liver biopsies. It has been associated with varying etiologies, mainly viral infections, drug toxicity, and autoimmunity. Here, we report an 18-year-old, previously healthy man with acute liver failure, who showed giant cell hepatitis in a liver biopsy. There was no evidence of viral hepatitis A-E, autoimmunity, and no drug history. Diagnostic work-up revealed Wilsons disease as the underlying disease. As syncytial giant cell formation is thought to be a uniform reaction pattern not related to any specific etiology, copper toxicity in Wilsons disease might cause giant cell formation. In contrast, our patient recalled a recent cytomegalovirus infection, which was confirmed serologically. Therefore, the giant cell formation might also be a fingerprint of an intercurrent cytomegalovirus infection as the common trigger for both giant cell hepatitis and decompensation of Wilsons disease.
Immunotherapy of solid tumors is often hampered by the low frequency of tumor-specific T cells elicited by current vaccination strategies. Here we describe a prime-boost vaccination protocol based on the administration of antigen conjugated to PLGA microspheres followed by booster vaccination with Listeria monocytogenes vectors, which rapidly generates potent immune responses within two weeks. Compared with conventional vaccination with antigen-pulsed dendritic cells, the use of PLGA microspheres resulted in immune responses of significantly higher magnitude, which could be further enhanced via co-injection of Toll-like receptor 3 agonists. In an immunocompetent model of subcutaneous hepatocellular carcinoma, PLGA/Listeria vaccination resulted in complete remission of established tumors and prolonged survival. To further test the efficacy of the novel vaccination for the treatment of solid tumors, we developed an orthotopic liver cancer model based on the injection of transposon-flanked plasmids expressing oncogenes and model antigens. In this transgenic mouse model of liver cancer, PLGA/Listeria vaccination resulted in eradication of liver tumors, long-term survival of animals and establishment of stable cancer-specific memory CD8(+) T-cell populations. Therefore, combined PLGA/Listeria vaccination holds promise as a novel immunotherapeutic option for the treatment of solid cancers and as a means to boost the therapeutic efficacy of established cancer vaccines. This article is protected by copyright. All rights reserved.
Mouse Double Minute homolog 4 (MDM4) gene upregulation often occurs in human hepatocellular carcinoma (HCC), but the molecular mechanisms responsible for its induction remain poorly understood. Here, we investigated the role of the phosphoinositide-3-kinase/v-akt murine thymoma viral oncogene homolog/mammalian target of Rapamycin (PI3K/AKT/mTOR) axis in the regulation of MDM4 levels in HCC. The activity of MDM4 and the PI3K/AKT/mTOR pathway was modulated in human HCC cell lines via silencing and overexpression experiments. Expression of main pathway components was analyzed in an AKT mouse model and human HCCs. MDM4 inhibition resulted in growth restraint of HCC cell lines both in vitro and in vivo. Inhibition of the PI3K-AKT and/or mTOR pathways lowered MDM4 protein levels in HCC cells and reactivated p53-dependent transcription. De-ubiquitination by ubiquitin-specific protease 2a and AKT-mediated phosphorylation protected MDM4 from proteasomal degradation and increased AKT protein stability. The eukaryotic elongation factor 1A2 (EEF1A2) was identified as an upstream inducer of PI3K supporting MDM4 stabilization. Also, we detected MDM4 protein upregulation in an AKT mouse model and a strong correlation between the expression of EEF1A2, activated/phosphorylated AKT, and MDM4 in human HCC (each rho>.8, P<.001). Noticeably, a strong activation of this cascade was associated with shorter patients survival. Conclusions: The EEF1A2/PI3K/AKT/mTOR axis promotes the protumorigenic stabilization of the MDM4 protooncogene in human HCC via a post-transcriptional mechanism. The activation level of the EEF1A2/PI3K/AKT/mTOR/MDM4 axis significantly influences the survival probability of HCC patients in vivo and may thus represent a promising molecular target. (Hepatology 2013;).
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