ABSTRACT
17-ß-hydroxysteroid dehydrogenase 13 (HSD17B13), a lipid droplet-associated enzyme, is primarily expressed in the liver and plays an important role in lipid metabolism. Targeted inhibition of enzymatic function is a potential therapeutic strategy for treating steatotic liver disease (SLD). The present study is aimed at investigating the effects of the first selective HSD17B13 inhibitor, BI-3231, in a model of hepatocellular lipotoxicity using human cell lines and primary mouse hepatocytes in vitro. Lipotoxicity was induced with palmitic acid in HepG2 cells and freshly isolated mouse hepatocytes and the cells were coincubated with BI-3231 to assess the protective effects. Under lipotoxic stress, triglyceride (TG) accumulation was significantly decreased in the BI-3231-treated cells compared with that of the control untreated human and mouse hepatocytes. In addition, treatment with BI-3231 led to considerable improvement in hepatocyte proliferation, cell differentiation, and lipid homeostasis. Mechanistically, BI-3231 increased the mitochondrial respiratory function without affecting ß-oxidation. BI-3231 inhibited the lipotoxic effects of palmitic acid in hepatocytes, highlighting the potential of targeting HSD17B13 as a specific therapeutic approach in steatotic liver disease.NEW & NOTEWORTHY 17-ß-Hydroxysteroid dehydrogenase 13 (HSD17B13) is a lipid droplet protein primarily expressed in the liver hepatocytes. HSD17B13 is associated with the clinical outcome of chronic liver diseases and is therefore a target for the development of drugs. Here, we demonstrate the promising therapeutic effect of BI-3231 as a potent inhibitor of HSD17B13 based on its ability to inhibit triglyceride accumulation in lipid droplets (LDs), restore lipid metabolism and homeostasis, and increase mitochondrial activity in vitro.
Subject(s)
Fatty Liver , Palmitic Acid , Humans , Animals , Mice , Palmitic Acid/toxicity , Enzyme Inhibitors/pharmacology , Hepatocytes , TriglyceridesABSTRACT
INTRODUCTION: WNT1-inducible signalling pathway protein 1 (WISP1) promotes progression of several tumor entities often correlating with worse prognosis. Here its expression regulation and role in the progression of chronic liver diseases (CLD) was investigated. METHODS: WISP1 expression was analyzed in human HCC datasets, in biopsies and serum samples and an HCC patient tissue microarray (TMA) including correlation to clinicopathological parameters. Spatial distribution of WISP1 expression was determined using RNAscope analysis. Regulation of WISP1 expression was investigated in cytokine-stimulated primary mouse hepatocytes (PMH) by array analysis and qRT-PCR. Outcome of WISP1 stimulation was analyzed by IncuCyte S3-live cell imaging, qRT-PCR, and immunoblotting in murine AML12 cells. RESULTS: In a TMA, high WISP1 expression was positively correlated with early HCC stages and male sex. Highest WISP1 expression levels were detected in patients with cirrhosis as compared to healthy individuals, patients with early fibrosis, and non-cirrhotic HCC in liver biopsies, expression datasets and serum samples. WISP1 transcripts were predominantly detected in hepatocytes of cirrhotic rather than tumorous liver tissue. High WISP1 expression was associated with better survival. In PMH, AML12 and HepaRG, WISP1 was identified as a specific TGF-ß1 target gene. Accordingly, expression levels of both cytokines positively correlated in human HCC patient samples. WISP1-stimulation induced the expression of Bcl-xL, PCNA and p21 in AML12 cells. CONCLUSIONS: WISP1 expression is induced by TGF-ß1 in hepatocytes and is associated with cirrhotic liver disease. We propose a crucial role of WISP1 in balancing pro- and anti-tumorigenic effects during premalignant stages of CLD.
Subject(s)
CCN Intercellular Signaling Proteins , Carcinogenesis , Gene Expression Regulation, Neoplastic , Liver Cirrhosis , Liver Neoplasms , Tumor Microenvironment , CCN Intercellular Signaling Proteins/genetics , CCN Intercellular Signaling Proteins/metabolism , Liver Cirrhosis/genetics , Liver Cirrhosis/pathology , Liver Neoplasms/genetics , Liver Neoplasms/pathology , Gene Expression Profiling , Survival Analysis , Humans , Male , Female , Animals , Mice , Hepatocytes/metabolism , Transforming Growth Factor beta1/genetics , Transforming Growth Factor beta1/metabolism , Apoptosis/genetics , Cell Proliferation/genetics , Cell Cycle Checkpoints/genetics , Tumor Microenvironment/genetics , Carcinogenesis/geneticsABSTRACT
BACKGROUND AND AIMS: Current liver-directed gene therapies look for adeno-associated virus (AAV) vectors with improved efficacy. With this background, capsid engineering is explored. Whereas shuffled capsid library screenings have resulted in potent liver targeting variants with one first vector in human clinical trials, modifying natural serotypes by peptide insertion has so far been less successful. Here, we now report on two capsid variants, MLIV.K and MLIV.A, both derived from a high-throughput in vivo AAV peptide display selection screen in mice. APPROACH AND RESULTS: The variants transduce primary murine and human hepatocytes at comparable efficiencies, a valuable feature in clinical development, and show significantly improved liver transduction efficacy, thereby allowing a dose reduction, and outperform parental AAV2 and AAV8 in targeting human hepatocytes in humanized mice. The natural heparan sulfate proteoglycan binding ability is markedly reduced, a feature that correlates with improved hepatocyte transduction. A further property that might contribute to the improved transduction efficacy is the lower capsid melting temperature. Peptide insertion also caused a moderate change in sensitivity to human sera containing anti-AAV2 neutralizing antibodies, revealing the impact of epitopes located at the basis of the AAV capsid protrusions. CONCLUSIONS: In conclusion, MLIV.K and MLIV.A are AAV peptide display variants selected in immunocompetent mice with improved hepatocyte tropism and transduction efficiency. Because these features are maintained across species, MLIV variants provide remarkable potential for translation of therapeutic approaches from mice to men.
Subject(s)
Capsid , Dependovirus , Animals , Mice , Humans , Capsid/chemistry , Capsid/metabolism , Serogroup , Dependovirus/genetics , Transduction, Genetic , Genetic Vectors , Liver/metabolism , Peptides/analysis , Peptides/genetics , Peptides/metabolism , Genetic Therapy/methodsABSTRACT
Liver cirrhosis is the end stage of all chronic liver diseases and contributes significantly to overall mortality of 2% globally. The age-standardized mortality from liver cirrhosis in Europe is between 10 and 20% and can be explained by not only the development of liver cancer but also the acute deterioration in the patient's overall condition. The development of complications including accumulation of fluid in the abdomen (ascites), bleeding in the gastrointestinal tract (variceal bleeding), bacterial infections, or a decrease in brain function (hepatic encephalopathy) define an acute decompensation that requires therapy and often leads to acute-on-chronic liver failure (ACLF) by different precipitating events. However, due to its complexity and organ-spanning nature, the pathogenesis of ACLF is poorly understood, and the common underlying mechanisms leading to the development of organ dysfunction or failure in ACLF are still elusive. Apart from general intensive care interventions, there are no specific therapy options for ACLF. Liver transplantation is often not possible in these patients due to contraindications and a lack of prioritization. In this review, we describe the framework of the ACLF-I project consortium funded by the Hessian Ministry of Higher Education, Research and the Arts (HMWK) based on existing findings and will provide answers to these open questions.
Subject(s)
Acute-On-Chronic Liver Failure , End Stage Liver Disease , Esophageal and Gastric Varices , Humans , End Stage Liver Disease/complications , Esophageal and Gastric Varices/complications , Gastrointestinal Hemorrhage/complications , Liver Cirrhosis/complications , Liver Cirrhosis/therapy , Acute-On-Chronic Liver Failure/therapy , Acute-On-Chronic Liver Failure/etiologyABSTRACT
CEND-1 (iRGD) is a bifunctional cyclic peptide that can modulate the solid tumour microenvironment, enhancing the delivery and therapeutic index of co-administered anti-cancer agents. This study explored CEND-1's pharmacokinetic (PK) properties pre-clinically and clinically, and assessed CEND-1 distribution, tumour selectivity and duration of action in pre-clinical tumour models. Its PK properties were assessed after intravenous infusion of CEND-1 at various doses in animals (mice, rats, dogs and monkeys) and patients with metastatic pancreatic cancer. To assess tissue disposition, [3H]-CEND-1 radioligand was administered intravenously to mice bearing orthotopic 4T1 mammary carcinoma, followed by tissue measurement using quantitative whole-body autoradiography or quantitative radioactivity analysis. The duration of the tumour-penetrating effect of CEND-1 was evaluated by assessing tumour accumulation of Evans blue and gadolinium-based contrast agents in hepatocellular carcinoma (HCC) mouse models. The plasma half-life was approximately 25 min in mice and 2 h in patients following intravenous administration of CEND-1. [3H]-CEND-1 localised to the tumour and several healthy tissues shortly after administration but was cleared from most healthy tissues by 3 h. Despite the rapid systemic clearance, tumours retained significant [3H]-CEND-1 several hours post-administration. In mice with HCC, the tumour penetration activity remained elevated for at least 24 h after the injection of a single dose of CEND-1. These results indicate a favourable in vivo PK profile of CEND-1 and a specific and sustained tumour homing and tumour penetrability. Taken together, these data suggest that even single injections of CEND-1 may elicit long-lasting tumour PK improvements for co-administered anti-cancer agents.
Subject(s)
Antineoplastic Agents , Carcinoma, Hepatocellular , Liver Neoplasms , Rats , Mice , Animals , Dogs , Infusions, Intravenous , Peptides , Tumor MicroenvironmentABSTRACT
Hepatocellular carcinoma (HCC) is highly resistant to anticancer therapy and novel therapeutic strategies are needed. Chronotherapy may become a promising approach because it may improve the efficacy of antimitotic radiation and chemotherapy by considering timing of treatment. To date little is known about time-of-day dependent changes of proliferation and DNA damage in HCC. Using transgenic c-myc/transforming growth factor (TGFα) mice as HCC animal model, we immunohistochemically demonstrated Ki67 as marker for proliferation and γ-H2AX as marker for DNA damage in HCC and surrounding healthy liver (HL). Core clock genes (Per1, Per2, Cry1, Cry2, Bmal 1, Rev-erbα and Clock) were examined by qPCR. Data were obtained from samples collected ex vivo at four different time points and from organotypic slice cultures (OSC). Significant differences were found between HCC and HL. In HCC, the number of Ki67 immunoreactive cells showed two peaks (ex vivo: ZT06 middle of day and ZT18 middle of night; OSC: CT04 and CT16). In ex vivo samples, the number of γ-H2AX positive cells in HCC peaked at ZT18 (middle of the night), while in OSC their number remained high during subjective day and night. In both HCC and HL, clock gene expression showed a time-of-day dependent expression ex vivo but no changes in OSC. The expression of Per2 and Cry1 was significantly lower in HCC than in HL. Our data support the concept of chronotherapy of HCC. OSC may become useful to test novel cancer therapies.
Subject(s)
Carcinoma, Hepatocellular/genetics , Liver Neoplasms/genetics , Neoplasms, Experimental/genetics , Period Circadian Proteins/genetics , Animals , Carcinoma, Hepatocellular/chemically induced , Carcinoma, Hepatocellular/pathology , Carcinoma, Hepatocellular/therapy , Cell Proliferation/genetics , Chlorides/administration & dosage , Chlorides/toxicity , Chronotherapy , DNA Damage , Gene Expression Regulation, Neoplastic , Humans , Liver/pathology , Liver Neoplasms/chemically induced , Liver Neoplasms/pathology , Liver Neoplasms/therapy , Mice , Mice, Transgenic , Neoplasms, Experimental/chemically induced , Neoplasms, Experimental/therapy , Photoperiod , Proto-Oncogene Proteins c-myc/genetics , Transforming Growth Factor alpha/genetics , Tumor Cells, Cultured , Zinc Compounds/administration & dosage , Zinc Compounds/toxicityABSTRACT
OBJECTIVE: TGF-ß2 (TGF-ß, transforming growth factor beta), the less-investigated sibling of TGF-ß1, is deregulated in rodent and human liver diseases. Former data from bile duct ligated and MDR2 knockout (KO) mouse models for human cholestatic liver disease suggested an involvement of TGF-ß2 in biliary-derived liver diseases. DESIGN: As we also found upregulated TGFB2 in liver tissue of patients with primary sclerosing cholangitis (PSC) and primary biliary cholangitis (PBC), we now fathomed the positive prospects of targeting TGF-ß2 in early stage biliary liver disease using the MDR2-KO mice. Specifically, the influence of TgfB2 silencing on the fibrotic and inflammatory niche was analysed on molecular, cellular and tissue levels. RESULTS: TgfB2-induced expression of fibrotic genes in cholangiocytes and hepatic stellate cellswas detected. TgfB2 expression in MDR2-KO mice was blunted using TgfB2-directed antisense oligonucleotides (AON). Upon AON treatment, reduced collagen deposition, hydroxyproline content and αSMA expression as well as induced PparG expression reflected a significant reduction of fibrogenesis without adverse effects on healthy livers. Expression analyses of fibrotic and inflammatory genes revealed AON-specific regulatory effects on Ccl3, Ccl4, Ccl5, Mki67 and Notch3 expression. Further, AON treatment of MDR2-KO mice increased tissue infiltration by F4/80-positive cells including eosinophils, whereas the number of CD45-positive inflammatory cells decreased. In line, TGFB2 and CD45 expression correlated positively in PSC/PBC patients and localised in similar areas of the diseased liver tissue. CONCLUSIONS: Taken together, our data suggest a new mechanistic explanation for amelioration of fibrogenesis by TGF-ß2 silencing and provide a direct rationale for TGF-ß2-directed drug development.
Subject(s)
Cholangitis, Sclerosing , Gene Silencing , Liver Cirrhosis, Biliary , Liver Cirrhosis , Oligonucleotides, Antisense , Transforming Growth Factor beta2/genetics , Transforming Growth Factor beta2/metabolism , ATP Binding Cassette Transporter, Subfamily B/genetics , Animals , Cholangitis, Sclerosing/metabolism , Cholangitis, Sclerosing/pathology , Disease Models, Animal , Drug Discovery , Gene Expression Regulation , Hepatic Stellate Cells/metabolism , Humans , Liver Cirrhosis/metabolism , Liver Cirrhosis/pathology , Liver Cirrhosis/prevention & control , Liver Cirrhosis, Biliary/metabolism , Liver Cirrhosis, Biliary/pathology , Mice , Mice, Knockout , Up-Regulation , ATP-Binding Cassette Sub-Family B Member 4ABSTRACT
BACKGROUND/AIMS: Signaling of Gs protein-coupled receptors (GsPCRs) is accomplished by stimulation of adenylyl cyclase, causing an increase of the intracellular cAMP concentration, activation of the intracellular cAMP effectors protein kinase A (PKA) and Epac, and an efflux of cAMP, the function of which is still unclear. METHODS: Activation of adenylyl cyclase by GsPCR agonists or cholera toxin was monitored by measurement of the intracellular cAMP concentration by ELISA, anti-phospho-PKA substrate motif phosphorylation by immunoblotting, and an Epac-FRET assay in the presence and absence of adenosine receptor antagonists or ecto-nucleotide phosphodiesterase/pyrophosphatase2 (eNPP2) inhibitors. The production of AMP from cAMP by recombinant eNPP2 was measured by HPLC. Extracellular adenosine was determined by LC-MS/MS, extracellular ATP by luciferase and LC-MS/MS. The expression of eNPP isoenzymes 1-3 was examined by RT-PCR. The expression of multidrug resistance protein 4 was suppressed by siRNA. RESULTS: Here we show that the activation of GsPCRs and the GsPCRs-independent activation of Gs proteins and adenylyl cyclase by cholera toxin induce stimulation of cell surface adenosine receptors (A2A or A2B adenosine receptors). In PC12 cells stimulation of adenylyl cyclase by GsPCR or cholera toxin caused activation of A2A adenosine receptors by an autocrine signaling pathway involving cAMP efflux through multidrug resistance protein 4 and hydrolysis of released cAMP to AMP by eNPP2. In contrast, in PC3 cells cholera toxin- and GsPCR-induced stimulation of adenylyl cyclase resulted in the activation of A2B adenosine receptors. CONCLUSION: Our findings show that stimulation of adenylyl cyclase causes a remarkable activation of cell surface adenosine receptors.
Subject(s)
Adenylyl Cyclases/metabolism , Receptor, Adenosine A2A/metabolism , Receptor, Adenosine A2B/metabolism , Animals , Cyclic AMP/metabolism , Enzyme Activation , GTP-Binding Protein alpha Subunits, Gs/metabolism , PC12 Cells , Rats , Signal TransductionABSTRACT
Radiation therapy is one of the most commonly used non-surgical interventions in tumor treatment and is often combined with other modalities to enhance its efficacy. Despite recent advances in radiation oncology, treatment responses, however, vary considerably between individual patients. A variety of approaches have been developed to enhance radiation response or to counteract resistance to ionizing radiation. Among them, a relatively novel class of radiation sensitizers comprises nanoparticles (NPs) which are highly efficient and selective systems in the nanometer range. NPs can either encapsulate radiation sensitizing agents, thereby protecting them from degradation, or sensitize cancer cells to ionizing radiation via their physicochemical properties, e.g. high Z number. Moreover, they can be chemically modified for active molecular targeting and the imaging of tumors. In this review we will focus on recent developments in nanotechnology, different classes and modifications of NPs and their radiation sensitizing properties.
Subject(s)
Nanoparticles , Radiotherapy , Antineoplastic Agents/therapeutic use , Clinical Trials as Topic , Drug Carriers , Humans , Magnetics , PhotochemotherapyABSTRACT
BACKGROUND & AIMS: Hepatocyte death is an important factor in development and progression of cirrhosis. Cytokeratin 18-based serum markers reflecting apoptotic (M30) and overall epithelial cell death (M65 and M65EpiDeath) have been used as prognostic parameters for survival in patients with acute liver failure. However, there has been no trial investigating M30, M65 and M65EpiDeath as survival parameters in patients with cirrhosis and acute-on-chronic liver failure. METHODS: Patients with cirrhosis were enrolled and followed until death, liver transplantation or last contact. M30, M65 and M65EpiDeath serum levels were quantified in patient's sera. RESULTS: Three hundred and thirty-one patients were screened and 211 patients could be included in this study. The median duration of follow-up was 322 days with a range of 1-1382 days. All three cell death parameters correlated with the extent of the severity of the disease. However, M65EpiDeath was the only of the three parameters which was associated with the severe complications of cirrhosis including ascites, spontaneous bacterial peritonitis and hepatorenal syndrome. Additionally, M65EpiDeath was the only cell death parameter which was independently from liver function and its surrogate parameter such as Child-Pugh score and the model of end-stage liver disease associated with overall survival. CONCLUSIONS: Epithelial cell death reflected by M65EpiDeath serum levels is an indicator for the severity of cirrhosis and a prognostic survival parameter in cirrhotic patients.
Subject(s)
Cell Death , Keratin-18/blood , Liver Cirrhosis/blood , Liver Cirrhosis/mortality , Peptide Fragments/blood , Adult , Aged , Ascites/etiology , Biomarkers/blood , Disease Progression , Female , Germany , Hepatorenal Syndrome/etiology , Humans , Liver Cirrhosis/complications , Male , Middle Aged , Multivariate Analysis , Peritonitis/etiology , Peritonitis/microbiology , Prognosis , Proportional Hazards Models , Prospective StudiesABSTRACT
The impact of the RNA-binding protein HuR for the post-transcriptional deregulation of tumor-relevant genes is well established. Despite of elevations in HuR expression levels, an increase in cytoplasmic HuR abundance in many cases correlates with a high grade of malignancy. Here, we demonstrated that administration of the actin-depolymerizing macrolide latrunculin A, or blebbistatin, an inhibitor of myosin II ATPase activity, caused a dose- and time-dependent reduction in the high cytoplasmic HuR content of HepG2 and Huh7 hepatocellular carcinoma (HCC) cells. Subcellular fractionation revealed that in addition, both inhibitors strongly attenuated cytoskeletal and membrane-bound HuR abundance and conversely increased the HuR amount in nuclear cell fractions. Concomitant with changes in intracellular HuR localization, both cytoskeletal inhibitors markedly decreased the half-lives of cyclooxygenase-2 (COX-2), cyclin A and cyclin D1 encoding mRNAs resulting in a significant reduction in their expression levels in HepG2 cells. Importantly, a similar reduction in the expression of these HuR targets was achieved by a RNA interference (RNAi)-mediated knockdown of either HuR or nonmuscle myoin IIA. Using polysomal fractionation, we further demonstrate that the decrease in cytoplasmic HuR by latrunculin A or blebbistatin is accompanied by a marked change in the allocation of HuR and its mRNA cargo from polysomes to ribonucleoprotein (RNP) particles. Functionally, the basal migration and prostaglandin E2 synthesis are similarly impaired in inhibitor-treated and stable HuR-knockdown HepG2 cells. Our data demonstrate that interfering with the actomyosin-dependent HuR trafficking may comprise a valid therapeutic option for antagonizing pathologic posttranscriptional gene expression by HuR and furthermore emphasize the potential benefit of HuR inhibitory strategies for treatment of HCC.
Subject(s)
Antineoplastic Agents/pharmacology , Bridged Bicyclo Compounds, Heterocyclic/pharmacology , Carcinoma, Hepatocellular/metabolism , ELAV Proteins/metabolism , Heterocyclic Compounds, 4 or More Rings/pharmacology , Liver Neoplasms/metabolism , Thiazolidines/pharmacology , Cyclin A/genetics , Cyclin A/metabolism , Cyclin D/genetics , Cyclin D/metabolism , Cyclooxygenase 2/genetics , Cyclooxygenase 2/metabolism , Cytoskeleton/drug effects , Dinoprostone/metabolism , Hep G2 Cells , Humans , Nonmuscle Myosin Type IIA/genetics , Nonmuscle Myosin Type IIA/metabolism , Polyribosomes/metabolism , Protein Transport , RNA, Messenger/genetics , RNA, Messenger/metabolism , Ribonucleoproteins/metabolismABSTRACT
Sorafenib is the standard treatment for patients with advanced hepatocellular carcinoma (HCC). However, the median overall survival (OS) benefit is only ~3 months, and sufficient biomarkers predicting treatment response are not available. The aim of the present study was to evaluate miRNA expression patterns from HCC tissue biopsies as potential biomarkers in patients under sorafenib treatment. Nineteen patients with advanced HCC treated with sorafenib were included. RNA was extracted from formalin-fixed paraffin-embedded (FFPE) liver biopsies. miRNA expression profiling of 818 mature miRNAs was performed using GeneChip® miRNA Array 2.0 (Affymetrix). Global miRNA patterns were assessed using unsupervised hierarchical clustering analysis (UCA), and specific miRNAs with correlation with disease control rate (DCR) or good OS were evaluated by pairwise supervised analyses. UCA divided the patients into three distinct groups by their miRNA expression patterns. However, DCR or OS did not correlate with these sub-groups. We have identified several miRNAs that correlated with either DCR or OS (P<0.05). However, with correction for multiple testing, these results did not reach statistical significance in this small cohort. Global miRNA analysis from very low input RNA deriving from liver biopsies showed distinctive clustering of molecular sub-groups in patients with intermediate and advanced HCC. Clinical response including OS under sorafenib did not correlate with global miRNA expression patterns, but we have identified candidate miRNAs for the prediction of DCR and OS to be evaluated in prospective studies and larger patient cohorts.
Subject(s)
Antineoplastic Agents/therapeutic use , Carcinoma, Hepatocellular/metabolism , Liver Neoplasms/metabolism , MicroRNAs/metabolism , Niacinamide/analogs & derivatives , Phenylurea Compounds/therapeutic use , Biopsy, Fine-Needle , Carcinoma, Hepatocellular/drug therapy , Carcinoma, Hepatocellular/pathology , Feasibility Studies , Female , Gene Expression Profiling/methods , Gene Expression Regulation, Neoplastic/drug effects , Gene Expression Regulation, Neoplastic/genetics , Genetic Markers/genetics , Humans , Liver Neoplasms/drug therapy , Liver Neoplasms/pathology , Male , Middle Aged , Niacinamide/therapeutic use , Oligonucleotide Array Sequence Analysis/methods , Real-Time Polymerase Chain Reaction , Retrognathia , Sorafenib , Treatment OutcomeABSTRACT
Autophagy is a highly conserved cellular process that allows degradation of large macromolecules. p62/SQSTM1 is a key adaptor protein that interacts both with material to be degraded and with LC3 at the autophagosome, enabling degradation of cargos such as protein aggregates, lipid droplets and damaged organelles by selective autophagy. Dysregulation of autophagy contributes to the pathogenesis of many diseases. In this study, we investigated if the interaction of p62/SQSTM1 with LC3B could be regulated. We purified full-length p62/SQSTM1 and established an in vitro assay that measures the interaction with LC3B. We used the assay to determine the role of the different domains of p62/SQSTM1 in the interaction with LC3B. We identified a mechanism of regulation of p62/SQSTM1 where the ZZ and the PB1 domains regulate the exposure of the LIR-sequence to enable or inhibit the interaction with LC3B. A mutation to mimic the phosphorylation of a site on the ZZ domain leads to increased interaction with LC3B. Also, a small compound that binds to the ZZ domain enhances interaction with LC3B. Dysregulation of these mechanisms in p62/SQSTM1 could have implications for diseases where autophagy is affected. In conclusion, our study highlights the regulated nature of p62/SQSTM1 and its ability to modulate the interaction with LC3B through a LIR-sequence Accessibility Mechanism (LAM). Furthermore, our findings suggest the potential for pharmacological modulation of the exposure of LIR, paving the way for future therapeutic strategies.
Subject(s)
Autophagosomes , Microtubule-Associated Proteins , Autophagosomes/metabolism , Sequestosome-1 Protein/genetics , Sequestosome-1 Protein/metabolism , Microtubule-Associated Proteins/genetics , Microtubule-Associated Proteins/metabolism , Adaptor Proteins, Signal Transducing/genetics , Adaptor Proteins, Signal Transducing/metabolism , Autophagy/geneticsABSTRACT
BACKGROUND: The accuracy of blood-based early tumour recognition is compromised by signal production at non-tumoral sites, low amount of signal produced by small tumours, and variable tumour production. Here we examined whether tumour-specific enhancement of vascular permeability by the particular tumour homing peptide, iRGD, which carries dual function of binding to integrin receptors overexpressed in the tumour vasculature and is known to promote extravasation via neuropilin-1 receptor upon site-specific cleavage, might be useful to improve blood-based tumour detection by inducing a yet unrecognised vice versa tumour-to-blood transport. METHODS: To detect an iRGD-induced tumour-to-blood transport, we examined the effect of intravenously injected iRGD on blood levels of α-fetoprotein (AFP) and autotaxin in several mouse models of hepatocellular carcinoma (HCC) or in mice with chronic liver injury without HCC, and on prostate-specific antigen (PSA) levels in mice with prostate cancer. FINDINGS: Intravenously injected iRGD rapidly and robustly elevated the blood levels of AFP in several mouse models of HCC, but not in mice with chronic liver injury. The effect was primarily seen in mice with small tumours and normal basal blood AFP levels, was attenuated by an anti-neuropilin-1 antibody, and depended on the concentration gradient between tumour and blood. iRGD treatment was also able to increase blood levels of autotaxin in HCC mice, and of PSA in mice with prostate cancer. INTERPRETATION: We conclude that iRGD induces a tumour-to-blood transport in a tumour-specific fashion that has potential of improving diagnosis of early stage cancer. FUNDING: Deutsche Krebshilfe, DKTK, LOEWE-Frankfurt Cancer Institute.
Subject(s)
Biomarkers, Tumor , Carcinoma, Hepatocellular , Disease Models, Animal , Liver Neoplasms , Phosphoric Diester Hydrolases , Animals , Mice , Biomarkers, Tumor/blood , Phosphoric Diester Hydrolases/blood , Phosphoric Diester Hydrolases/metabolism , Carcinoma, Hepatocellular/blood , Carcinoma, Hepatocellular/diagnosis , Liver Neoplasms/blood , Liver Neoplasms/diagnosis , Liver Neoplasms/metabolism , alpha-Fetoproteins/metabolism , Male , Humans , Cell Line, Tumor , Prostatic Neoplasms/diagnosis , Prostatic Neoplasms/blood , Prostatic Neoplasms/pathology , Prostatic Neoplasms/metabolism , Oligopeptides/administration & dosageABSTRACT
Protein kinase C-related protein kinases (PRKs) are effectors of the Rho family of small GTPases and play a role in the development of diseases such as prostate cancer and hepatitis C. Here we examined the mechanism underlying the regulation of PRK2 by its N-terminal region. We show that the N-terminal region of PRK2 prevents the interaction with its upstream kinase, the 3-phosphoinositide-dependent kinase 1 (PDK1), which phosphorylates the activation loop of PRK2. We confirm that the N-terminal region directly inhibits the kinase activity of PRK2. However, in contrast to previous models, our data indicate that this inhibition is mediated in trans through an intermolecular PRK2-PRK2 interaction. Our results also suggest that amino acids 487-501, located in the linker region between the N-terminal domains and the catalytic domain, contribute to the PRK2-PRK2 dimer formation. This dimerization is further supported by other N-terminal domains. Additionally, we provide evidence that the region C-terminal to the catalytic domain intramolecularly activates PRK2. Finally, we discovered that the catalytic domain mediates a cross-talk between the inhibitory N-terminal region and the activating C-terminal region. The results presented here describe a novel mechanism of regulation among AGC kinases and offer new insights into potential approaches to pharmacologically regulate PRK2.
Subject(s)
Protein Kinase C/metabolism , Protein Multimerization/physiology , Enzyme Activation/physiology , HEK293 Cells , Humans , Phosphorylation/physiology , Protein Kinase C/genetics , Protein Serine-Threonine Kinases/genetics , Protein Serine-Threonine Kinases/metabolism , Protein Structure, Secondary , Protein Structure, Tertiary , Pyruvate Dehydrogenase Acetyl-Transferring KinaseABSTRACT
Epithelial-mesenchymal transition (EMT) is an important mechanism to initiate cancer invasion and metastasis. Bone morphogenetic protein (BMP)-9 is a member of the transforming growth factor (TGF)-ß superfamily. It has been suggested to play a role in cancer development in some non-hepatic tumors. In the present study, two hepatocellular carcinoma (HCC) lines, HLE and HepG2, were treated with BMP-9 in vitro, and phenotypic changes and cell motility were analyzed. In situ hybridization (ISH) and immunohistochemical analyses were performed with human HCC tissue samples in order to assess expression levels of BMP-9. In vivo, BMP-9 protein and mRNA were expressed in all the tested patients to diverse degrees. At the protein level, mildly positive (1 + ) BMP-9 staining could be observed in 25/41 (61%), and moderately to strongly positive (2 + ) in 16/41 (39%) of the patients. In 27/41 (65%) patients, the BMP-9 protein expression level was consistent with the mRNA expression level as measured by ISH. In those patients with 2 + protein level, nuclear pSmad1 expression in cancer cells was also significantly increased. Expression of BMP-9 was positively related to nuclear Snail expression and reversely correlated to cell surface E-cadherin expression, although this did not reach statistical significance. Expression levels of BMP-9 were significantly associated with the T stages of the investigated tumors and high levels of BMP-9 were detected by immunofluorescence especially at the tumor borders in samples from an HCC mouse model. In vitro, BMP-9 treatment caused a reduction of E-cadherin and ZO-1 and an induction of Vimentin and Snail expression. Furthermore, cell migration was enhanced by BMP-9 in both HCC cell lines. These results imply that EMT induced by BMP-9 is related to invasiveness of HCC.
Subject(s)
Carcinoma, Hepatocellular/metabolism , Carcinoma, Hepatocellular/pathology , Liver Neoplasms/metabolism , Liver Neoplasms/pathology , Cadherins/metabolism , Cell Line, Tumor , Epithelial-Mesenchymal Transition , Female , Growth Differentiation Factor 2 , Humans , Male , Middle AgedABSTRACT
BACKGROUND & AIMS: Soluble CD163 (sCD163) is shed in the blood circulation by activated macrophages, correlates strongly with the hepatic venous pressure gradient (HVPG) and is thereby a good indicator of portal hypertension. It is unknown whether sCD163 correlates with the risk of variceal bleeding and overall survival (OS) in patients with liver cirrhosis. We performed a prospective study to investigate if sCD163 serum levels correlate with the risk of variceal bleeding and OS in cirrhotic patients. METHODS: Patients with liver cirrhosis were prospectively enrolled and followed until death or last contact. At the day of inclusion in the study, blood samples were taken and sCD163 serum levels were assessed by ELISA (enzyme-linked immunosorbent assay). The time until the end points death and variceal bleeding was assessed and the risks of death or variceal bleeding were calculated with uni- and multivariate Cox regression analyses. RESULTS: High sCD163 levels (>4100 ng/L) were associated with death independently of the MELD (model of end stage liver disease) score, CRP (C-reactive protein), age and gender. Furthermore, high sCD163 levels were associated with gastrointestinal bleeding independently of the variceal stage and red spots. CONCLUSIONS: The sCD163 serum level is a new independent non-invasive risk factor for death and variceal bleeding in cirrhotic patients.
Subject(s)
Esophageal and Gastric Varices/diagnosis , Esophageal and Gastric Varices/epidemiology , Liver Cirrhosis/diagnosis , Liver Cirrhosis/mortality , Macrophage Activation/physiology , Adult , Aged , Aged, 80 and over , Antigens, CD/blood , Antigens, Differentiation, Myelomonocytic/blood , Biomarkers/blood , Esophageal and Gastric Varices/immunology , Female , Humans , Hypertension, Portal/diagnosis , Hypertension, Portal/epidemiology , Hypertension, Portal/immunology , Liver Cirrhosis/immunology , Male , Middle Aged , Prognosis , Prospective Studies , Receptors, Cell Surface/blood , Risk Factors , Severity of Illness Index , Survival RateABSTRACT
BACKGROUND & AIMS: The serum cell death parameters M30 and M65 and the macrophage activation marker sCD163 (soluble CD163) are elevated in patients with acute and chronic liver diseases. However, their diagnostic and prognostic potential in patients with hepatocellular carcinoma (HCC) has not yet been investigated. METHODS: Serum levels of M30, M65, and sCD163 were measured in two cohorts of HCC patients and a cohort of cirrhotic patients. The parameters were compared between patients with and without HCC and the overall survival (OS) times according to M30, M65, and sCD163 were assessed. RESULTS: M30 and M65 levels were higher in HCC patients than in cirrhotic patients (both p < 0.001). M65 was an independent parameter for non-invasive identification of HCC patients by logistic regression analysis and could supplement AFP (alpha-fetoprotein) and abdominal ultrasound in non-invasive detection of HCC patients. High M65 serum levels as well as high sCD163 concentrations were associated with an impaired prognosis in univariate Cox regression analysis. The sCD163 level was associated with OS independently of the CLIP (Cancer of the Liver Italian Program) score, the BCLC (Barcelona Clinic Liver Cancer) stage, and the CRP (C-reactive protein) level in a multivariate Cox regression model. CONCLUSIONS: Serum M65 has the potential as a new diagnostic parameter for HCC and serum sCD163 is a new prognostic parameter in HCC patients.
Subject(s)
Antigens, CD/blood , Antigens, Differentiation, Myelomonocytic/blood , Biomarkers, Tumor/blood , Carcinoma, Hepatocellular/blood , Keratin-18/blood , Liver Neoplasms/blood , Macrophage Activation , Peptide Fragments/blood , Receptors, Cell Surface/blood , Aged , Carcinoma, Hepatocellular/diagnosis , Case-Control Studies , Cell Death , Cohort Studies , Female , Humans , Liver Cirrhosis/blood , Liver Neoplasms/diagnosis , Male , Middle Aged , PrognosisABSTRACT
Different from regular small molecule contrast agents, nanoparticle-based contrast agents have a longer circulation time and can be modified with ligands to confer tissue-specific contrasting properties. We evaluated the tissue distribution of polymeric nanoparticles (NPs) prepared from human serum albumin (HSA), loaded with gadolinium-diethylenetriaminepentaacetic acid (Gd-DTPA) (Gd-HSA-NP), and coated with folic acid (FA) (Gd-HSA-NP-FA) in mice by magnetic resonance imaging (MRI). FA increases the affinity of the Gd-HSA-NP to FA receptor-expressing cells. Clinical 3 T MRI was used to evaluate the signal intensities in the different organs of mice injected with Gd-DTPA, Gd-HSA-NP, or Gd-HSA-NP-FA. Signal intensities were measured and standardized by calculating the signal to noise ratios. In general, the NP-based contrast agents provided stronger contrasting than Gd-DTPA. Gd-HSA-NP-FA provided a significant contrast enhancement (CE) in the brain (p â=â .0032), whereas Gd-DTPA or Gd-HSA-NP did not. All studied MRI contrast agents showed significant CE in the blood, kidney, and liver (p < .05). Gd-HSA-NP-FA elicited significantly higher CE in the blood than Gd-HSA-NP (p â=â .0069); Gd-HSA-NP and Gd-HSA-NP-FA did not show CE in skeletal muscle and gallbladder; Gd-HSA-NP, but not Gd-HSA-NP-FA, showed CE in the cardiac muscle. Gd-HSA-NP-FA has potential as an MRI contrast agent in the brain.