ObjectiveThe HBV HBx regulatory protein is required for transcription from the covalently closed circular DNA (cccDNA) minichromosome and affects the epigenetic control of both viral and host cellular chromatin.DesignWe explored, in relevant cellular models of HBV replication, the functional consequences of HBx interaction with DLEU2, a long non-coding RNA (lncRNA) expressed in the liver and increased in human hepatocellular carcinoma (HCC), in the regulation of host target genes and the HBV cccDNA.ResultsWe show that HBx binds the promoter region, enhances the transcription and induces the accumulation of DLEU2 in infected hepatocytes. We found that nuclear DLEU2 directly binds HBx and the histone methyltransferase enhancer of zeste homolog 2 (EZH2), the catalytic active subunit of the polycomb repressor complex 2 (PRC2) complex. Computational modelling and biochemical evidence suggest that HBx and EZH2 share two preferential binding sites in DLEU2 intron 1. HBx and DLEU2 co-recruitment on the cccDNA displaces EZH2 from the viral chromatin to boost transcription and viral replication. DLEU2-HBx association with target host promoters relieves EZH2 repression and leads to the transcriptional activation of a subset of EZH2/PRC2 target genes in HBV-infected cells and HBV-related HCCs.ConclusionsOur results highlight the ability of HBx to bind RNA to impact on the epigenetic control of both viral cccDNA and host genes and provide a new key to understand the role of DLEU2 and EZH2 overexpression in HBV-related HCCs and HBx contribution to hepatocytes transformation.
Superficial pT1 bladder tumors are characterized by a high risk of recurrence and progression in grade and stage. Few studies provided evidence that loss of adipocyte-fatty acid binding protein (A-FABP) expression was associated with bladder cancer progression. A-FABP is a lipid binding protein playing a role in intracellular lipid transport and metabolism, as well as in signal transduction. We reported from bladder tumors that decrease of A-FABP transcript level significantly correlated to tumor stage and to histologic grade (p < 0.05). Namely, in poor prognosis high grade pT1 tumors there was a loss of A-FABP expression compared to good prognosis tumors suggesting that re-expression of A-FABP could be a therapeutic approach in early stage bladder cancer to prevent disease progression. We demonstrated for the first time that this marker is upregulated by Peroxisome Proliferator-Activated Receptor (PPAR) a, b and c in T24 cells (derived from an undifferentiated grade III carcinoma) and only by PPARb in RT4 cells (derived from a well differentiated grade I papillary tumor). This effect occurred through a PPAR-dependent transcriptional mechanism without modifying mRNA stability and interestingly required de novo protein synthesis. Data as a whole suggest a prognostic significance of A-FABP in bladder cancer outcome and the potential utility of overexpression of this protein by PPAR agonists open up new perspectives in the treatment of bladder cancer.
HCV induces oxidative stress but controls it tightly by inducing ROS scavengers. Among these, GPx4 plays an essential role in the HCV life cycle. Modulating oxidative stress in CHC by specifically targeting GPx4 may lower specific infectivity of virions and prevent hepatocarcinogenesis, especially in patients who remain difficult to be treated in the new era of interferon-free regimens.
Thiazolidinediones, including rosiglitazone and troglitazone, are insulin-sensitizing drugs and high-affinity ligands for the peroxisome proliferator-activated receptor c (PPARc). Apart from their antidiabetic activity, these molecules possess antitumor properties. We investigated their potential apoptotic effects on RT4 (derived from a well-differentiated Grade I papillary tumor) and T24 (derived from an undifferentiated Grade III carcinoma) bladder cancer cells. Rosiglitazone induced G2/M or G0/G1 phase cell cycle arrest in RT4 and T24 cells, respectively. Only troglitazone triggered apoptosis via extrinsic and intrinsic pathways in both cell lines. Interestingly, rosiglitazone amplified TRAIL-induced apoptosis in TRAIL-sensitive RT4 cells or let TRAIL-resistant T24 cells to respond to TRAIL. Thiazolidinediones acted through PPARc activation-independent mechanisms. The underlying mechanisms involved for the first time in cancer cells the upregulation of soluble and/or membrane-bound TRAIL. This was associated with increased cell surface death receptor 5 expression and c-FLIP and survivin downregulation, mediated in part through proteasome-dependent degradation in troglitazone-promoted cell death. Therefore, the combination of rosiglitazone and TRAIL could be clinically relevant as chemopreventive or therapeutic agents for the treatment of TRAILresistant high-grade urothelial cancers.Bladder cancer accounts for $5% of all cancer deaths in humans. Despite the advances with intravesical immuno-and chemotherapy, surgery and systemic chemotherapy in the management of patients and although new cytotoxic chemotherapeutic agents for either advanced or metastatic bladder cancer are used, no improvement in survival has been observed. Thus, targeted therapy with novel agents is a promising avenue to improve patient outcome.Thiazolidinediones (TZD), including rosiglitazone and troglitazone, are a class of insulin-sensitizing drugs. Besides, rosiglitazone is currently in clinical use for the treatment of type II diabetes.1,2 These TZD are high-affinity chemically synthesized ligands for the peroxisome proliferator-activated receptor c (PPARc).3 PPARc is a ligand-activated transcription factor of the nuclear hormone receptor superfamily. In addition to its known role in regulation of metabolism and inflammation, PPARc has also been implicated in carcinogenesis based on studies showing its ability to modulate cellular differentiation, proliferation and apoptosis. Apart from their antidiabetic activity, TZD elicit growth inhibitory effects in vitro on cancer cells of diverse tissue origins and in vivo. Few studies indicate that certain TZD members exhibited antiproliferative or proapoptotic activities against a broad spectrum of bladder cancer cell lines.5-8 Thus, treatment of the T24 bladder cancer cells with troglitazone induced G0/G1 cell cycle arrest and cell death.5 In addition, depending on TZD member, the induction of apoptosis is PPARc-dependent or -independent. 9 Interestingly, TZD could sensitize tumor cells to TRAI...
Hepatitis C virus (HCV) infection is a worldwide health problem and is one of the main causes of chronic hepatitis, liver cirrhosis, and hepatocellular carcinoma (HCC). Despite recent improvements, effective treatments for HCC are still missing and new tools for early detection are needed. Non-coding RNAs (ncRNAs) have emerged as important regulators of gene expression and key players in human carcinogenesis, including HCC. Aberrant expression of ncRNAs is associated with HCC metastasis, invasion, dissemination, and recurrence. This review will focus on the recent advances in ncRNA expression profiles, their dysregulation in HCV-related HCC, and the clinical perspective of ncRNA signatures for the early detection of HCC.
Background and Aims: Netrin-1 displays protumoral properties, though the pathological contexts and processes involved in its induction remain understudied. The liver is a major model of inflammation-associated cancer development, leading to HCC.
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Funding informationRomain Barnault and Ievgeniia Chicherova are recipients of a DevWeCan Labex (Laboratories of Excellence Network, ANR-LABX-061) and Agence Nationale de la Recherche sur le Sida et les Hepatites Virales (ECTZ63958) predoctoral fellowships, respectively.
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