Quantification of circulating HBV RNA expressed from intrahepatic cccDNA in untreated and NUC treated patients with chronic hepatitis B.

OBJECTIVE: A convenient, reproducible biomarker of hepatitis B virus (HBV) covalently closed circular DNA (cccDNA) transcriptional activity is lacking. We measured circulating HBV RNA (cirB-RNA) in untreated and nucleos(t)ide analogues (NUC) treated chronic hepatitis B (CHB) patients to define its correlation with intrahepatic viral markers and HBV core-related antigen (HBcrAg). DESIGN: Paired liver biopsy and serum samples were collected from 122 untreated and 30 NUC-treated CHB patients. We measured cirB-RNA, HBV DNA, hepatitis B surface antigen (HBsAg), HBcrAg and alanine aminotransferase levels. cirB-RNA was quantified using an investigational HBV RNA assay for use on the cobas 6800 system. The test detects a region spanning the HBV canonical polyadenylation site. cccDNA and 3.5 kb RNA in liver tissue were assessed by quantitative PCR and droplet digital PCR. RESULTS: cirB-RNA was detectable in 100% of HBeAg(+) chronic hepatitis (CH), 57% and 14% of HBeAg(-) CH and chronic infection untreated patients and 47% of NUC-treated patients. cirB-RNA undetectability was associated with lower intrahepatic cccDNA transcriptional activity, as well as serum HBcrAg, but no significant differences in HBsAg, in both untreated and treated patients. In untreated HBeAg(-) patients, cirB-RNA correlated with intrahepatic 3.5 kb RNA and cccDNA transcriptional activity, serum HBV DNA and HBcrAg, but not with HBsAg or total cccDNA levels. Combined undetectability of both cirB-RNA and HBcrAg detection in untreated HBeAg(-) patients identified a subgroup with the lowest levels of intrahepatic transcriptionally active cccDNA. CONCLUSION: Our results support the usefulness of quantification of circulating HBV RNA expressed from cccDNA as an indicator of intrahepatic active viral reservoir in both untreated and NUC-treated CHB patients. TRIAL REGISTRATION NUMBER: NCT02602847.

Evaluation of the HBV liver reservoir with fine needle aspirates.

Background & Aims: Finite duration of treatment associated with HBsAg loss is the current goal for improved therapeutic approaches against chronic HBV infection, as it indicates elimination or durable inactivation of intrahepatic covalently closed circular DNA (cccDNA). To assist drug development, the definition of early predictive markers of HBsAg loss by assessing their value in reflecting intrahepatic cccDNA levels and transcriptional activity is essential. Fine needle aspirates (FNAs) have recently emerged as a less invasive alternative to core liver biopsy (CLB) and showed to be useful for investigating intrahepatic immune responses. The aim of this study was to optimise and validate the use of FNA vs. CLB to evaluate the intrahepatic viral reservoir. Methods: Paired FNA/CLB samples were obtained from patients with HBeAg+ chronic hepatitis (n = 4), HBeAg- chronic hepatitis (n = 4), and HBeAg- chronic infection (n = 1). One HBeAg+ patient was undergoing tenofovir treatment. HBV 3.5-kb RNA and cccDNA were quantified by droplet digital PCR. Results: cccDNA was quantifiable in all but one FNA/CLB pair, showing the highest levels in untreated HBeAg+ patients, except for the tenofovir-treated patient. Similarly, 3.5-kb RNA was detectable in all but one FNA sample and showed higher levels in HBeAg+ patients. When comparing cccDNA and 3.5-kb RNA quantification in FNA vs. CLB samples, no statistically significant differences were identified. Conclusions: These results demonstrate the possibility to quantify cccDNA and assess its transcriptional activity in patients with chronic hepatitis B by combining FNA and droplet digital PCR. This supports the use of FNA in clinical trials to evaluate the intrahepatic viral reservoir during the development of new antivirals and immunomodulatory agents. Impact and implications: Chronic hepatitis B infection is characterised by a complex interplay between immune responses and viral replication in the liver, which determines the long-term outcome of the disease. In this study, we show that fine needle aspiration of the liver, a less-invasive alternative to core biopsies, allows the assessment of the hepatic viral reservoir.

Hepatic inflammation elicits production of proinflammatory netrin-1 through exclusive activation of translation.

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. APPROACH AND RESULTS: A panel of cell biology and biochemistry approaches (reverse transcription quantitative polymerase chain reaction, reporter assays, run-on, polysome fractionation, cross linking immunoprecipitation, filter binding assay, subcellular fractionation, western blotting, immunoprecipitation, stable isotope labeling by amino acids in cell culture) on in vitro-grown primary hepatocytes, human liver cell lines, mouse samples and clinical samples was used. We identify netrin-1 as a hepatic inflammation-inducible factor and decipher its mode of activation through an exhaustive eliminative approach. We show that netrin-1 up-regulation relies on a hitherto unknown mode of induction, namely its exclusive translational activation. This process includes the transfer of NTN1 (netrin-1) mRNA to the endoplasmic reticulum and the direct interaction between the Staufen-1 protein and this transcript as well as netrin-1 mobilization from its cell-bound form. Finally, we explore the impact of a phase 2 clinical trial-tested humanized anti-netrin-1 antibody (NP137) in two distinct, toll-like receptor (TLR) 2/TLR3/TLR6-dependent, hepatic inflammatory mouse settings. We observe a clear anti-inflammatory activity indicating the proinflammatory impact of netrin-1 on several chemokines and Ly6C+ macrophages. CONCLUSIONS: These results identify netrin-1 as an inflammation-inducible factor in the liver through an atypical mechanism as well as its contribution to hepatic inflammation.

Heparanase-1 is upregulated by hepatitis C virus and favors its replication.

BACKGROUND & AIMS: Over time, chronic HCV infection can lead to hepatocellular carcinoma (HCC), a process that involves changes to the liver extracellular matrix (ECM). However, the exact mechanisms by which HCV induces HCC remain unclear. Therefore, we sought to investigate the impact of HCV on the liver ECM, with a focus on heparanase-1 (HPSE). METHODS: HPSE expression was assessed by quantitative reverse-transcription PCR, immunoblotting and immunofluorescence in liver biopsies infected or not with HCV, and in 10-day-infected hepatoma Huh7.5 cells. Cell lines deficient for or overexpressing HPSE were established to study its role during infection. RESULTS: HCV propagation led to significant HPSE induction, in vivo and in vitro. HPSE enhanced infection when exogenously expressed or supplemented as a recombinant protein. Conversely, when HPSE expression was downregulated or its activity blocked, HCV infection dropped, suggesting a role of HPSE in the HCV life cycle. We further studied the underlying mechanisms of such observations and found that HPSE favored HCV release by enhancing CD63 synthesis and exosome secretion, but not by stimulating HCV entry or genome replication. We also showed that virus-induced oxidative stress was involved in HPSE induction, most likely through NF-κB activation. CONCLUSIONS: We report for the first time that HCV infection is favored by HPSE, and upregulates HPSE expression and secretion, which may result in pathogenic alterations of the ECM. LAY SUMMARY: Chronic hepatitis C virus (HCV) infection can lead to hepatocellular carcinoma development in a process that involves derangement of the extracellular matrix (ECM). Herein, we show that heparanase-1, a protein involved in ECM degradation and remodeling, favors HCV infection and is upregulated by HCV infection; this upregulation may result in pathogenic alterations of the ECM.

Copper Isotope Evidence of Oxidative Stress-Induced Hepatic Breakdown and the Transition to Hepatocellular Carcinoma.

Background and Aims: Hepatocellular carcinoma (HCC) is the third leading cause of cancer-related death worldwide, and finding a single reliable biomarker to follow liver degradation is a challenging task. To document the relationship between liver failure, hypoxia, and HCC, copper isotope variations (δ65Cu) were evaluated in the serum of HCC-negative and HCC-positive patients as a biomarker of hepatic failure. Methods: We analyzed Cu isotope variations in serum samples from 293 patients with potentially degraded liver functions presenting hepatitis B virus, hepatitis C virus, nonalcoholic steatohepatitis, and alcohol uptake (OH) etiologies and 105 controls. Ninety-five of the patients were diagnosed with HCC. Results: On average, the δ65Cu values of the serum of patients with F3-F4 fibrosis score or HCC-positive are low. The Cu isotope data are strikingly bimodal with well-defined δ65Cu modes which imperfectly reflect etiology. The population with normal values (ca -0.3‰) is progressively replaced by a population with atypical δ65Cu values (ca -0.8‰), which reflects the progressive degradation of hepatic functions. Conclusion: The clear bimodality does not correspond to a progressive shift of the δ65Cu values but to a replacement of one population by another. This bimodality sheds light on the persisting difficulties epitomized by α-fetoprotein in finding high-sensitivity and high-specificity HCC biomarkers. It is interpreted as a switch in the resistance of hepatic tissues to the oxidative stress that eventually leads to HCC oncogenesis.

Hepatitis B protein HBx binds the DLEU2 lncRNA to sustain cccDNA and host cancer-related gene transcription.

OBJECTIVE: The 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. DESIGN: We 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. RESULTS: We 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. CONCLUSIONS: Our 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.

Non-Coding RNAs and Hepatitis C Virus-Induced Hepatocellular Carcinoma.

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.

Hepatocellular carcinoma-associated depletion of the netrin-1 receptor Uncoordinated Phenotype-5A (UNC5A) skews the hepatic unfolded protein response towards prosurvival outcomes.

In the liver, HBV and HCV infections, exposure to toxics, genetic and metabolic disorders may induce endoplasmic reticulum (ER) stress and the unfolding protein response (UPR). The UPR allows cells to reach ER homeostasis after lumen overload, but also fosters survival of damaged cells and therefore HCC onset. Dependence receptors such as UNC5A trigger apoptosis when unbound to their ligands. We have previously shown that the main dependence receptor ligand, netrin-1, could protect cells against UPR-induced apoptosis through sustained translation. In this study, we show that UNC5A is cumulatively downregulated by the UPR at the transcriptional level in vitro and at the translational level both in vitro and in vivo. We have found that the 5'-untranslated region of the UNC5A mRNA shares a certain homology degree with that of netrin-1, suggesting linked translational regulatory mechanisms, at least during the initial stages of the UPR. RNAi and forced expression studies identified UNC5A as a modulator of cell death in the context of the UPR. UNC5A decrease of association with polysomes and expression oriented cells towards UPR-associated hepatocytic survival. Such data indicate that cooperation between the UPR and UNC5A depletion as previously observed by ourselves in HCC patients samples may foster liver cancer development and growth.

Cell death and restoration of TRAIL-sensitivity by ciglitazone in resistant cervical cancer cells.

Known activators of the Peroxisome Proliferator-Activated Receptor γ (PPARγ), thiazolidinediones (TZD) induce apoptosis in a variety of cancer cells through dependent and/or independent mechanisms of the receptor. We tested a panel of TZD (Rosiglitazone, Pioglitazone, Ciglitazone) to shed light on their potential therapeutic effects on three cervical cancer cell lines (HeLa, Ca Ski, C-33 A). In these cells, only ciglitazone triggered apoptosis through PPARγ-independent mechanisms and in particular via both extrinsic and intrinsic pathways in Ca Ski cells containing Human PapillomaVirus (HPV) type 16. It also inhibits cervical cancer xenograft development in nude mice. Ciglitazone kills cervical cancer cells by activating death receptor signalling pathway, caspase cascade and BH3 interacting-domain death agonist (Bid) cleavage through the up-regulation of Death Receptor 4 (DR4)/DR5 and soluble and membrane-bound TNF related apoptosis inducing ligand (TRAIL). Importantly, the drug let TRAIL-resistant Ca Ski cells to respond to TRAIL through the downregulation of cellular FLICE-Like Inhibitory Protein (c-FLIP) level. For the first time, we revealed that ciglitazone is able to decrease E6 viral oncoprotein expression known to block TRAIL pathway and this was associated with cell death. Our results highlight the capacity of ciglitazone to restore TRAIL sensitivity and to prevent E6 blocking action to induce apoptosis in cervical cancer cells.

Epidermal Growth Factor Receptor-Dependent Mutual Amplification between Netrin-1 and the Hepatitis C Virus.

Hepatitis C virus (HCV) is an oncogenic virus associated with the onset of hepatocellular carcinoma (HCC). The present study investigated the possible link between HCV infection and Netrin-1, a ligand for dependence receptors that sustains tumorigenesis, in particular in inflammation-associated tumors. We show that Netrin-1 expression is significantly elevated in HCV+ liver biopsies compared to hepatitis B virus (HBV+) and uninfected samples. Furthermore, Netrin-1 was upregulated in all histological stages of HCV+ hepatic lesions, from minimal liver fibrosis to cirrhosis and HCC, compared to histologically matched HCV- tissues. Both cirrhosis and HCV contributed to the induction of Netrin-1 expression, whereas anti-HCV treatment resulted in a reduction of Netrin-1 expression. In vitro, HCV increased the level and translation of Netrin-1 in a NS5A-La-related protein 1 (LARP1)-dependent fashion. Knockdown and forced expression experiments identified the receptor uncoordinated receptor-5 (UNC5A) as an antagonist of the Netrin-1 signal, though it did not affect the death of HCV-infected cells. Netrin-1 enhanced infectivity of HCV particles and promoted viral entry by increasing the activation and decreasing the recycling of the epidermal growth factor receptor (EGFR), a protein that is dysregulated in HCC. Netrin-1 and HCV are, therefore, reciprocal inducers in vitro and in patients, as seen from the increase in viral morphogenesis and viral entry, both phenomena converging toward an increase in the level of infectivity of HCV virions. This functional association involving a cancer-related virus and Netrin-1 argues for evaluating the implication of UNC5 receptor ligands in other oncogenic microbial species.

Netrin-1 Protects Hepatocytes Against Cell Death Through Sustained Translation During the Unfolded Protein Response.

BACKGROUND & AIMS: Netrin-1, a multifunctional secreted protein, is up-regulated in cancer and inflammation. Netrin-1 blocks apoptosis induced by the prototypical dependence receptors deleted in colorectal carcinoma and uncoordinated phenotype-5. Although the unfolded protein response (UPR) triggers apoptosis on exposure to stress, it first attempts to restore endoplasmic reticulum homeostasis to foster cell survival. Importantly, UPR is implicated in chronic liver conditions including hepatic oncogenesis. Netrin-1's implication in cell survival on UPR in this context is unknown. METHODS: Isolation of translational complexes, determination of RNA secondary structures by selective 2'-hydroxyl acylation and primer extension/dimethyl sulfate, bicistronic constructs, as well as conventional cell biology and biochemistry approaches were used on in vitro-grown hepatocytic cells, wild-type, and netrin-1 transgenic mice. RESULTS: HepaRG cells constitute a bona fide model for UPR studies in vitro through adequate activation of the 3 sensors of the UPR (protein kinase RNA-like endoplasmic reticulum kinase (PERK)), inositol requiring enzyme 1α (IRE1α), and activated transcription factor 6 (ATF6). The netrin-1 messenger RNA 5'-end was shown to fold into a complex double pseudoknot and bear E-loop motifs, both of which are representative hallmarks of related internal ribosome entry site regions. Cap-independent translation of netrin 5' untranslated region-driven luciferase was observed on UPR in vitro. Unlike several structurally related oncogenic transcripts (l-myc, c-myc, c-myb), netrin-1 messenger RNA was selected for translation during UPR both in human hepatocytes and in mice livers. Depletion of netrin-1 during UPR induces apoptosis, leading to cell death through an uncoordinated phenotype-5A/C-mediated involvement of protein phosphatase 2A and death-associated protein kinase 1 in vitro and in netrin transgenic mice. CONCLUSIONS: UPR-resistant, internal ribosome entry site-driven netrin-1 translation leads to the inhibition of uncoordinated phenotype-5/death-associated protein kinase 1-mediated apoptosis in the hepatic context during UPR, a hallmark of chronic liver disease.

Glutathione peroxidase 4 is reversibly induced by HCV to control lipid peroxidation and to increase virion infectivity.

OBJECTIVE: Inflammation and oxidative stress drive disease progression in chronic hepatitis C (CHC) towards hepatocellular carcinoma. HCV is known to increase intracellular levels of reactive oxygen species (ROS), but how it eliminates ROS is less well known. The role of the ROS scavenger glutathione peroxidase 4 (GPx4), induced by HCV, in the viral life cycle was analysed. DESIGN: The study was performed using a replicative in vitro HCV infection model and liver biopsies derived from two different CHC patient cohorts. RESULTS: A screen for HCV-induced peroxide scavengers identified GPx4 as a host factor required for HCV infection. The physiological role of GPx4 is the elimination of lipid peroxides from membranes or lipoproteins. GPx4-silencing reduced the specific infectivity of HCV by up to 10-fold. Loss of infectivity correlated with 70% reduced fusogenic activity of virions in liposome fusion assays. NS5A was identified as the protein that mediates GPx4 induction in a phosphatidylinositol-3-kinase-dependent manner. Levels of GPx4 mRNA were found increased in vitro and in CHC compared with control liver biopsies. Upon successful viral eradication, GPx4 transcript levels returned to baseline in vitro and also in the liver of patients. CONCLUSIONS: 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.

Diversity of hepatocellular carcinoma clones bearing hematopoietic malignancies-related chromosomal translocation.

Interpatient heterogeneity of hepatocellular carcinoma has been in-depth addressed. Intrapatient heterogeneity is less known. Four clones were freshly isolated from an Edmondson grade I HCV-associated hepatocellular carcinoma. Biochemical approaches, functional assays and cytogenetics were used. Albumin inducibility was uncoupled from canonical cytokeratin profiles, suggesting pathological combinations of hepatospecific and biliary markers. Poor differentiation and TGFß's proproliferative effect on all clones were observed. TGFß, Interferon α and doxorubicin sensitivity levels were found highly heterogeneous. Progenitor and stem cells markers OV6 and EpCAM were mutually exclusively expressed. All clones were CD44+, while none expressed CD90, CD133, or CD117. Three clones displayed a liver progenitor OV6+ phenotype, and were susceptible to hepatocytic differentiation, among which one fibroblastoid clone displayed intrahepatic parenchymal engraftment capability. A fourth clone, the less motile, displayed a cancer stem cell EpCAM+ phenotype, was essentially ß-catenin negative, and was as expected devoid of hepatocytic differentiation capability, yet the most sensitive to doxorubicin treatment. Cytogenetics evidenced in all clones a t(12;22)(p11;q11) translocation found in several myelodysplastic syndromes. All clones, that probably derive from EpCAM+ tumor cells, display aberrant E-cadherin cytosolic localization. Because of their diverse pathophysiolocal features, these freshly isolated, low population doubling-defined, HCC clones may provide novel opportunities to tackle HCC heterogeneity in a single patient background for therapy improvement purposes, especially regarding recently developed targeted strategies.

The antidiabetic drug ciglitazone induces high grade bladder cancer cells apoptosis through the up-regulation of TRAIL.

BACKGROUND: Ciglitazone belongs to the thiazolidinediones class of antidiabetic drug family and is a high-affinity ligand for the Peroxisome Proliferator-Activated Receptor γ (PPARγ). Apart from its antidiabetic activity, this molecule shows antineoplastic effectiveness in numerous cancer cell lines. METHODOLOGY/PRINCIPAL FINDINGS: Using RT4 (derived from a well differentiated grade I papillary tumor) and T24 (derived from an undifferentiated grade III carcinoma) bladder cancer cells, we investigated the potential of ciglitazone to induce apoptotic cell death and characterized the molecular mechanisms involved. In RT4 cells, the drug induced G2/M cell cycle arrest characterized by an overexpression of p53, p21(waf1/CIP1) and p27(Kip1) in concomitance with a decrease of cyclin B1. On the contrary, in T24 cells, it triggered apoptosis via extrinsic and intrinsic pathways. Cell cycle arrest and induction of apoptosis occurred at high concentrations through PPARγ activation-independent pathways. We show that in vivo treatment of nude mice by ciglitazone inhibits high grade bladder cancer xenograft development. We identified a novel mechanism by which ciglitazone kills cancer cells. Ciglitazone up-regulated soluble and membrane-bound TRAIL and let TRAIL-resistant T24 cells to respond to TRAIL through caspase activation, death receptor signalling pathway and Bid cleavage. We provided evidence that TRAIL-induced apoptosis is partially driven by ciglitazone-mediated down-regulation of c-FLIP and survivin protein levels through a proteasome-dependent degradation mechanism. CONCLUSIONS/SIGNIFICANCE: Therefore, ciglitazone could be clinically relevant as chemopreventive or therapeutic agent for the treatment of TRAIL-refractory high grade urothelial cancers.

Sodium butyrate with UCN-01 has marked antitumour activity against cervical cancer cells.

AIM: The effect of combining sodium butyrate (NaB), a histone deacetylase inhibitor, and 7-hydroxy-staurosporine (UCN-01) on cytotoxicity in human cervical carcinoma cells was evaluated. MATERIALS AND METHODS: HeLa and CaSki cells were treated using NaB alone or in combination with staurosporine (STS) or its analog UCN-01. Cytotoxicity was determined by flow cytometry and morphological assays. Apoptotic pathways were characterized by Western blotting and immunostaining. CaSki cells were also xenografted into nude mice to assess the in vivo effects of NaB/UCN-01 combination. RESULTS: Treatment with NaB and STS or UCN-01 resulted in enhanced apoptosis of cancer cells. Apoptosis involved mitochondrial pathways and overexpression of p53 and p73. In concordance, co-treatment modulated some p53/p73 downstream targets such as p21, BAX, BCL-2 and BCL-X(L), leading to increased caspase-3 and poly(ADP-ribose) polymerase cleavage. In vivo, NaB/UCN-01 combination exerted a substantial tumour growth suppression effect compared with single treatment. CONCLUSION: UCN-01 was shown to be a potentiator of NaB therapy for cervical cancer cells.

Insights on distinct pathways of thiazolidinediones (PPARgamma ligand)-promoted apoptosis in TRAIL-sensitive or -resistant malignant urothelial cells.

Thiazolidinediones, including rosiglitazone and troglitazone, are insulin-sensitizing drugs and high-affinity ligands for the peroxisome proliferator-activated receptor gamma (PPARgamma). 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 PPARgamma 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 TRAIL-resistant high-grade urothelial cancers.

A-FABP, a candidate progression marker of human transitional cell carcinoma of the bladder, is differentially regulated by PPAR in urothelial cancer cells.

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) alpha, beta and gamma in T24 cells (derived from an undifferentiated grade III carcinoma) and only by PPARbeta 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. (c) 2008 Wiley-Liss, Inc.

The human papillomavirus type 18 E6 oncoprotein induces Vascular Endothelial Growth Factor 121 (VEGF121) transcription from the promoter through a p53-independent mechanism.

Altered angiogenic response is associated with high-grade cervical dysplasia and with invasive squamous carcinoma of the cervix. Vascular Endothelial Growth Factor (VEGF) is one of the most potent inducers of angiogenesis and is up-regulated in carcinoma of the cervix. Infection by high-risk human papillomavirus and persistent expression of viral oncogene E6 are etiologically linked to the development of cervical cancer. E6 is able to immortalize cells and induce malignant transformation by inactivating p53. In cervical cancer, regulation of VEGF expression is poorly described. Thus, we investigated whether E6 oncoprotein could regulate VEGF expression in HPV18-positive cervical cancer-derived HeLa cells harboring a wild-type p53. The alternative splicing of vegf mRNA renders three major isoforms of 121, 165 and 189 amino-acids in humans. We have designed isoform specific real time QRT-PCR assays to quantitate vegf transcripts and VEGF121 was the predominant isoform. Silencing HPV18 E6 mRNA with specific siRNA reduced VEGF121 expression by at least 50% whereas silencing of p53 did not alter its expression. Treatment with cycloheximide did not inhibit E6-induced VEGF121 expression. Collectively, these results suggest that HPV18 E6 oncoprotein contributes to tumor angiogenesis by inducing VEGF transcription from the promoter in a p53-independent manner.