Publications by authors named "Aurélie Morin"

22 Publications

  • Page 1 of 1

Loss of SDHB Promotes Dysregulated Iron Homeostasis, Oxidative Stress, and Sensitivity to Ascorbate.

Cancer Res 2021 Jul 14;81(13):3480-3494. Epub 2021 Jun 14.

PARCC, INSERM UMR970, Equipe Labellisée par la Ligue Contre le Cancer, Paris, France.

Succinate dehydrogenase is a key enzyme in the tricarboxylic acid cycle and the electron transport chain. All four subunits of succinate dehydrogenase are tumor suppressor genes predisposing to paraganglioma, but only mutations in the SDHB subunit are associated with increased risk of metastasis. Here we generated an knockout chromaffin cell line and compared it with deficient cells. Both cell types exhibited similar SDH loss of function, metabolic adaptation, and succinate accumulation. In contrast, cells showed hallmarks of mesenchymal transition associated with increased DNA hypermethylation and a stronger pseudo-hypoxic phenotype compared with cells. Loss of SDHB specifically led to increased oxidative stress associated with dysregulated iron and copper homeostasis in the absence of NRF2 activation. High-dose ascorbate exacerbated the increase in mitochondrial reactive oxygen species, leading to cell death in cells. These data establish a mechanism linking oxidative stress to iron homeostasis that specifically occurs in -deficient cells and may promote metastasis. They also highlight high-dose ascorbate as a promising therapeutic strategy for SDHB-related cancers. SIGNIFICANCE: Loss of different succinate dehydrogenase subunits can lead to different cell and tumor phenotypes, linking stronger 2-OG-dependent dioxygenases inhibition, iron overload, and ROS accumulation following SDHB mutation.
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http://dx.doi.org/10.1158/0008-5472.CAN-20-2936DOI Listing
July 2021

TET-Mediated Hypermethylation Primes SDH-Deficient Cells for HIF2α-Driven Mesenchymal Transition.

Cell Rep 2020 03;30(13):4551-4566.e7

Université de Paris, PARCC, INSERM, Equipe Labellisée par la Ligue contre le Cancer, 75015 Paris, France. Electronic address:

Loss-of-function mutations in the SDHB subunit of succinate dehydrogenase predispose patients to aggressive tumors characterized by pseudohypoxic and hypermethylator phenotypes. The mechanisms leading to DNA hypermethylation and its contribution to SDH-deficient cancers remain undemonstrated. We examine the genome-wide distribution of 5-methylcytosine and 5-hydroxymethylcytosine and their correlation with RNA expression in SDHB-deficient tumors and murine Sdhb cells. We report that DNA hypermethylation results from TET inhibition. Although it preferentially affects PRC2 targets and known developmental genes, PRC2 activity does not contribute to the DNA hypermethylator phenotype. We also prove, in vitro and in vivo, that TET silencing, although recapitulating the methylation profile of Sdhb cells, is not sufficient to drive their EMT-like phenotype, which requires additional HIF2α activation. Altogether, our findings reveal synergistic roles of TET repression and pseudohypoxia in the acquisition of metastatic traits, providing a rationale for targeting HIF2α and DNA methylation in SDH-associated malignancies.
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http://dx.doi.org/10.1016/j.celrep.2020.03.022DOI Listing
March 2020

Germline Mutations in the Mitochondrial 2-Oxoglutarate/Malate Carrier Gene Confer a Predisposition to Metastatic Paragangliomas.

Cancer Res 2018 04 5;78(8):1914-1922. Epub 2018 Feb 5.

INSERM, UMR970, Paris-Centre de Recherche Cardiovasculaire, Paris, France; Equipe labellisée Ligue contre le Cancer.

Comprehensive genetic analyses have identified germline and gene mutations as predominant causes of metastatic paraganglioma and pheochromocytoma. However, some suspicious cases remain unexplained. In this study, we performed whole-exome sequencing of a paraganglioma exhibiting an -like molecular profile in the absence of or mutations and identified a germline mutation in the gene, which encodes the mitochondrial 2-oxoglutarate/malate carrier. Germline mutations were identified in six other patients, five of whom had metastatic disease. These mutations were associated with loss of heterozygosity, suggesting that acts as a tumor-suppressor gene. Pseudohypoxic and hypermethylator phenotypes comparable with those described in - and -related tumors were observed both in tumors with mutated and in immortalized mouse chromaffin knockout cells generated by CRISPR-Cas9 technology. These data show that is a novel paraganglioma susceptibility gene for which loss of function correlates with metastatic presentation. A gene encoding a mitochondrial carrier is implicated in a hereditary cancer predisposition syndrome, expanding the role of mitochondrial dysfunction in paraganglioma. .
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http://dx.doi.org/10.1158/0008-5472.CAN-17-2463DOI Listing
April 2018

Rodent models of pheochromocytoma, parallels in rodent and human tumorigenesis.

Cell Tissue Res 2018 05 9;372(2):379-392. Epub 2018 Feb 9.

INSERM UMR970, Paris-Cardiovascular Research Center, Equipe Labellisée Ligue Contre le Cancer, 56 rue Leblanc, F-75015, Paris, France.

Paragangliomas and pheochromocytomas are rare neuroendocrine tumors characterized by a large spectrum of hereditary predisposition. Based on gene expression profiling classification, they can be classically assigned to either a hypoxic/angiogenic cluster (cluster 1 including tumors with mutations in SDHx, VHL and FH genes) or a kinase-signaling cluster (cluster 2 consisting in tumors related to RET, NF1, TMEM127 and MAX genes mutations, as well as most of the sporadic tumors). The past 15 years have seen the emergence of an increasing number of genetically engineered and grafted models to investigate tumorigenesis and develop new therapeutic strategies. Among them, only cluster 2-related predisposed models have been successful but grafted models are however available to study cluster 1-related tumors. In this review, we present an overview of existing rodent models targeting predisposition genes involved or not in human pheochromocytoma/paraganglioma susceptibility and their contribution to the improvement of pheochromocytoma experimental research.
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http://dx.doi.org/10.1007/s00441-018-2797-yDOI Listing
May 2018

Establishment of a mouse xenograft model of metastatic adrenocortical carcinoma.

Oncotarget 2017 Aug 7;8(31):51050-51057. Epub 2017 Apr 7.

Université Côte d'Azur, Valbonne, Sophia Antipolis, France.

Adrenocortical carcinoma is a rare neoplasm with a poor prognosis. Very important advances have been made in the identification of the genetic determinants of adrenocortical carcinoma pathogenesis but our understanding is still limited about the mechanisms that determine cancer spread and metastasis. One major problem hindering preclinical experimentation for new therapies for adrenocortical carcinoma is represented by the lack of suitable animal models for metastatic disease. With the aim to overcome these limitations, in this study we tested several protocols in order to establish a mouse xenograft model of metastatic adrenocortical carcinoma. The most efficient method, based upon intrasplenic injection followed by splenectomy, produced metastases with high efficiency, whose development could be followed over time by bioluminescence measurements. We expect that the availability of this model will greatly improve the possibilities for preclinical testing of new treatments for advanced-stage disease.
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http://dx.doi.org/10.18632/oncotarget.16909DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5584229PMC
August 2017

Dosage-dependent regulation of expression by steroidogenic factor-1 drives adrenocortical carcinoma cell invasion.

Sci Signal 2017 Mar 7;10(469). Epub 2017 Mar 7.

Université Côte d'Azur, Sophia Antipolis, 06560 Valbonne, France.

Adrenocortical carcinoma (ACC) is a rare endocrine malignancy with a dismal prognosis. Genomic studies have enabled progress in our understanding of the molecular bases of ACC, but factors that influence its prognosis are lacking. Amplification of the gene encoding the transcription factor steroidogenic factor-1 (SF-1; also known as NR5A1) is one of the genetic alterations common in ACC. We identified a transcriptional regulatory mechanism involving increased abundance of VAV2, a guanine nucleotide exchange factor for small GTPases that control the cytoskeleton, driven by increased expression of the gene encoding SF-1 in ACC. Manipulating SF-1 and VAV2 abundance in cultured ACC cells revealed that VAV2 was a critical factor for SF-1-induced cytoskeletal remodeling and invasion in culture (Matrigel) and in vivo (chicken chorioallantoic membrane) models. Analysis of ACC patient cohorts indicated that greater VAV2 abundance robustly correlated with poor prognosis in ACC patients. Because VAV2 is a druggable target, our findings suggest that blocking VAV2 may be a new therapeutic approach to inhibit metastatic progression in ACC patients.
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http://dx.doi.org/10.1126/scisignal.aal2464DOI Listing
March 2017

Loss of succinate dehydrogenase activity results in dependency on pyruvate carboxylation for cellular anabolism.

Nat Commun 2015 Nov 2;6:8784. Epub 2015 Nov 2.

Institute of Metabolism and Systems Research, College of Medical and Dental Sciences, University of Birmingham, Birmingham B15 2TT, UK.

The tricarboxylic acid (TCA) cycle is a central metabolic pathway responsible for supplying reducing potential for oxidative phosphorylation and anabolic substrates for cell growth, repair and proliferation. As such it thought to be essential for cell proliferation and tissue homeostasis. However, since the initial report of an inactivating mutation in the TCA cycle enzyme complex, succinate dehydrogenase (SDH) in paraganglioma (PGL), it has become clear that some cells and tissues are not only able to survive with a truncated TCA cycle, but that they are also able of supporting proliferative phenotype observed in tumours. Here, we show that loss of SDH activity leads to changes in the metabolism of non-essential amino acids. In particular, we demonstrate that pyruvate carboxylase is essential to re-supply the depleted pool of aspartate in SDH-deficient cells. Our results demonstrate that the loss of SDH reduces the metabolic plasticity of cells, suggesting vulnerabilities that can be targeted therapeutically.
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http://dx.doi.org/10.1038/ncomms9784DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4632646PMC
November 2015

In Vivo Detection of Succinate by Magnetic Resonance Spectroscopy as a Hallmark of SDHx Mutations in Paraganglioma.

Clin Cancer Res 2016 Mar 21;22(5):1120-9. Epub 2015 Oct 21.

INSERM, UMR970, Paris Cardiovascular Research Center, Paris, France. Université Paris Descartes, Sorbonne Paris Cité, Faculté de Médecine, Paris, France. Assistance Publique-Hôpitaux de Paris, Hôpital Européen Georges Pompidou, Service de Radiologie, Paris, France.

Purpose: Germline mutations in genes encoding mitochondrial succinate dehydrogenase (SDH) are found in patients with paragangliomas, pheochromocytomas, gastrointestinal stromal tumors, and renal cancers. SDH inactivation leads to a massive accumulation of succinate, acting as an oncometabolite and which levels, assessed on surgically resected tissue are a highly specific biomarker of SDHx-mutated tumors. The aim of this study was to address the feasibility of detecting succinate in vivo by magnetic resonance spectroscopy.

Experimental Design: A pulsed proton magnetic resonance spectroscopy ((1)H-MRS) sequence was developed, optimized, and applied to image nude mice grafted with Sdhb(-/-) or wild-type chromaffin cells. The method was then applied to patients with paraganglioma carrying (n = 5) or not (n = 4) an SDHx gene mutation. Following surgery, succinate was measured using gas chromatography/mass spectrometry, and SDH protein expression was assessed by immunohistochemistry in resected tumors.

Results: A succinate peak was observed at 2.44 ppm by (1)H-MRS in all Sdhb(-/-)-derived tumors in mice and in all paragangliomas of patients carrying an SDHx gene mutation, but neither in wild-type mouse tumors nor in patients exempt of SDHx mutation. In one patient, (1)H-MRS results led to the identification of an unsuspected SDHA gene mutation. In another case, it helped define the pathogenicity of a variant of unknown significance in the SDHB gene.

Conclusions: Detection of succinate by (1)H-MRS is a highly specific and sensitive hallmark of SDHx mutations. This noninvasive approach is a simple and robust method allowing in vivo detection of the major biomarker of SDHx-mutated tumors.
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http://dx.doi.org/10.1158/1078-0432.CCR-15-1576DOI Listing
March 2016

Deciphering the molecular basis of invasiveness in Sdhb-deficient cells.

Oncotarget 2015 Oct;6(32):32955-65

INSERM, UMR970, Paris Cardiovascular Research Centre, F-75015 Paris, France.

Metastatic pheochromocytomas and paragangliomas (PPGL) are malignant neuroendocrine tumors frequently associated with germline mutations in the SDHB gene. SDHB-mutated PPGL display a hypermethylator phenotype associated with hallmarks of epithelial-to-mesenchymal transition (EMT). In the present study, we report the characterization of a unique model of Sdhb knockout in mouse chromaffin cells. Sdhb deficient cells exhibit a metastatic phenotype as highlighted by increased individual cell migration (characterized by faster motility and increased persistence) as well as high invasive and adhesion abilities. This phenotype is associated with the modulation of Twist1, Twist2, Tcf3, Snai1, N-cadherin or Krt19 expression, reflecting an EMT-like reprogramming of cells. Krt19 is epigenetically silenced in Sdhb-deficient cells and re-expressed after treatment by the demethylating agent decitabine. Krt19 rescue by lentiviral transduction in Sdhb-deficient cells and Krt19 inhibition by RNA interference in wild-type cells were performed. Both studies revealed the involvement of KRT19 in the invasive phenotype by modulating collective and individual migration and cell/extra-cellular matrix adhesion properties. These findings underline the role of hypermethylation and EMT in the in vitro acquisition of metastatic properties, following SDHB loss of function.
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http://dx.doi.org/10.18632/oncotarget.5106DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4741742PMC
October 2015

From Nf1 to Sdhb knockout: Successes and failures in the quest for animal models of pheochromocytoma.

Mol Cell Endocrinol 2016 Feb 27;421:40-8. Epub 2015 Jun 27.

INSERM, UMR970, Paris-Cardiovascular Research Center, F-75015 Paris, France; Université Paris Descartes, Sorbonne Paris Cité, Faculté de Médecine, F-75006 Paris, France. Electronic address:

Pheochromocytomas and paragangliomas (PPGL) are rare neuroendocrine tumors characterized by a high frequency of hereditary forms. Based on transcriptome classification, PPGL can be classified in two different clusters. Cluster 1 tumors are caused by mutations in SDHx, VHL and FH genes and are characterized by a pseudohypoxic signature. Cluster 2 PPGL carry mutations in RET, NF1, MAX or TMEM127 genes and display an activation of the MAPK and mTOR signaling pathways. Many genetically engineered and allografted mouse models have been generated these past 30 years to investigate the mechanisms of PPGL tumorigenesis and test new therapeutic strategies. Among them, only Cluster 2-related models have been successful while no Cluster 1-related knockout mouse was so far reported to develop a PPGL. In this review, we present an overview of existing, successful or not, PPGL models, and a description of our own experience on the quest of Sdhb knockout mouse models of PPGL.
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http://dx.doi.org/10.1016/j.mce.2015.06.027DOI Listing
February 2016

Multi-omics analysis defines core genomic alterations in pheochromocytomas and paragangliomas.

Nat Commun 2015 Jan 27;6:6044. Epub 2015 Jan 27.

1] INSERM, UMR970, Paris-Cardiovascular Research Center, F-75015 Paris, France [2] Université Paris Descartes, Sorbonne Paris Cité, Faculté de Médecine, F-75006 Paris, France [3] Department of Genetics, Assistance Publique-Hôpitaux de Paris, Hôpital Européen Georges Pompidou, F-75015 Paris, France [4] Rare Adrenal Cancer Network COMETE, F-75006 Paris, France.

Pheochromocytomas and paragangliomas (PCCs/PGLs) are neural crest-derived tumours with a very strong genetic component. Here we report the first integrated genomic examination of a large collection of PCC/PGL. SNP array analysis reveals distinct copy-number patterns associated with genetic background. Whole-exome sequencing shows a low mutation rate of 0.3 mutations per megabase, with few recurrent somatic mutations in genes not previously associated with PCC/PGL. DNA methylation arrays and miRNA sequencing identify DNA methylation changes and miRNA expression clusters strongly associated with messenger RNA expression profiling. Overexpression of the miRNA cluster 182/96/183 is specific in SDHB-mutated tumours and induces malignant traits, whereas silencing of the imprinted DLK1-MEG3 miRNA cluster appears as a potential driver in a subgroup of sporadic tumours. Altogether, the complete genomic landscape of PCC/PGL is mainly driven by distinct germline and/or somatic mutations in susceptibility genes and reveals different molecular entities, characterized by a set of unique genomic alterations.
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http://dx.doi.org/10.1038/ncomms7044DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4354166PMC
January 2015

Oncometabolites-driven tumorigenesis: From genetics to targeted therapy.

Int J Cancer 2014 Nov 14;135(10):2237-48. Epub 2014 Aug 14.

INSERM, UMR970, Paris-Cardiovascular Research Center at HEGP, Paris, France; Faculté de Médecine, Université Paris Descartes, Paris, France.

Although the alteration of cellular metabolism in cancer was reported by Warburg in the early 1930s, a regain of interest in cancer metabolism has more recently followed the discovery of germline or somatic mutations in genes coding for metabolic enzymes (succinate dehydrogenase, fumarate hydratase and isocitrate dehydrogenase) that are associated with tumor susceptibility. Mutations in these genes are found in numerous tumor types including paragangliomas, kidney cancers, leiomyomas, glioblastomas and acute myeloid leukemia. They lead to the accumulation of so-called oncometabolites that behave as competitors of 2-oxoglutarate-dependent dioxygenases, involved in a broad spectrum of pathways such as hypoxic response and epigenetic reprogramming. Here, we review the diverse pathways affected by oncometabolites, their potential role in cancer formation, maintenance, metastasis and sensitivity to chemotherapies, as well as emerging new therapeutic strategies.
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http://dx.doi.org/10.1002/ijc.29080DOI Listing
November 2014

Germline mutations in FH confer predisposition to malignant pheochromocytomas and paragangliomas.

Hum Mol Genet 2014 May 13;23(9):2440-6. Epub 2013 Dec 13.

INSERM, UMR970, Paris-Cardiovascular Research Center, F-75015, Paris, France.

Malignant pheochromocytoma (PCC) and paraganglioma (PGL) are mostly caused by germline mutations of SDHB, encoding a subunit of succinate dehydrogenase. Using whole-exome sequencing, we recently identified a mutation in the FH gene encoding fumarate hydratase, in a PCC with an 'SDH-like' molecular phenotype. Here, we investigated the role of FH in PCC/PGL predisposition, by screening for germline FH mutations in a large international cohort of patients. We screened 598 patients with PCC/PGL without mutations in known PCC/PGL susceptibility genes. We searched for FH germline mutations and large deletions, by direct sequencing and multiplex ligation-dependent probe amplification methods. Global alterations in DNA methylation and protein succination were assessed by immunohistochemical staining for 5-hydroxymethylcytosine (5-hmC) and S-(2-succinyl) cysteine (2SC), respectively. We identified five pathogenic germline FH mutations (four missense and one splice mutation) in five patients. Somatic inactivation of the second allele, resulting in a loss of fumarate hydratase activity, was demonstrated in tumors with FH mutations. Low tumor levels of 5-hmC, resembling those in SDHB-deficient tumors, and positive 2SC staining were detected in tumors with FH mutations. Clinically, metastatic phenotype (P = 0.007) and multiple tumors (P = 0.02) were significantly more frequent in patients with FH mutations than those without such mutations. This study reveals a new role for FH in susceptibility to malignant and/or multiple PCC/PGL. Remarkably, FH-deficient PCC/PGLs display the same pattern of epigenetic deregulation as SDHB-mutated malignant PCC/PGL. Therefore, we propose that mutation screening for FH should be included in PCC/PGL genetic testing, at least for tumors with malignant behavior.
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http://dx.doi.org/10.1093/hmg/ddt639DOI Listing
May 2014

Of mice and men: fuzzy tandem repeats and divergent p53 transcriptional repertoires.

Transcription 2013 Mar-Apr;4(2):67-71. Epub 2013 Feb 14.

Institut Curie, Centre de Recherche, Paris, France.

The clinical importance of tumor suppressor p53 makes it one of the most studied transcription factors. A comparison of mammalian p53 transcriptional repertoires may help identify fundamental principles in genome evolution and better understand cancer processes. Here we summarize mechanisms underlying the divergence of mammalian p53 transcriptional repertoires, with an emphasis on the rapid evolution of fuzzy tandem repeats containing p53 response elements.
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http://dx.doi.org/10.4161/trns.23772DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3646056PMC
December 2013

Key role of intramolecular metal chelation and hydrogen bonding in the cobalt-mediated radical polymerization of N-vinyl amides.

Chemistry 2012 Oct 21;18(40):12834-44. Epub 2012 Aug 21.

Center for Education and Research on Macromolecules, Chemistry Department, University of Liège, Belgium.

This work reveals the preponderance of an intramolecular metal chelation phenomenon in a controlled radical polymerization system involving the reversible trapping of the radical chains by a cobalt complex bis(acetylacetonato)cobalt(II). The cobalt-mediated radical polymerization (CMRP) of a series of N-vinyl amides was considered with the aim of studying the effect of the cobalt chelation by the amide moiety of the last monomer unit of the chain. The latter reinforces the cobalt-polymer bond in the order N-vinylpyrrolidone
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http://dx.doi.org/10.1002/chem.201201456DOI Listing
October 2012

Risk of hormone escape in a human prostate cancer model depends on therapy modalities and can be reduced by tyrosine kinase inhibitors.

PLoS One 2012 6;7(8):e42252. Epub 2012 Aug 6.

Translational Research Department, Institut Curie, Paris, France.

Almost all prostate cancers respond to androgen deprivation treatment but many recur. We postulated that risk of hormone escape--frequency and delay--are influenced by hormone therapy modalities. More, hormone therapies induce crucial biological changes involving androgen receptors; some might be targets for escape prevention. We investigated the relationship between the androgen deprivation treatment and the risk of recurrence using nude mice bearing the high grade, hormone-dependent human prostate cancer xenograft PAC120. Tumor-bearing mice were treated by Luteinizing-Hormone Releasing Hormone (LHRH) antagonist alone, continuous or intermittent regimen, or combined with androgen receptor (AR) antagonists (bicalutamide or flutamide). Tumor growth was monitored. Biological changes were studied as for genomic alterations, AR mutations and protein expression in a large series of recurrent tumors according to hormone therapy modalities. Therapies targeting Her-2 or AKT were tested in combination with castration. All statistical tests were two-sided. Tumor growth was inhibited by continuous administration of the LH-RH antagonist degarelix (castration), but 40% of tumors recurred. Intermittent castration or complete blockade induced by degarelix and antiandrogens combination, inhibited tumor growth but increased the risk of recurrence (RR) as compared to continuous castration (RR(intermittent): 14.5, RR(complete blockade): 6.5 and 1.35). All recurrent tumors displayed new quantitative genetic alterations and AR mutations, whatever the treatment modalities. AR amplification was found after complete blockade. Increased expression of Her-2/neu with frequent ERK/AKT activation was detected in all variants. Combination of castration with a Her-2/neu inhibitor decreased recurrence risk (0.17) and combination with an mTOR inhibitor prevented it. Anti-hormone treatments influence risk of recurrence although tumor growth inhibition was initially similar. Recurrent tumors displayed genetic instability, AR mutations, and alterations of phosphorylation pathways. We postulated that Her-2/AKT pathways allowed salvage of tumor cells under castration and we demonstrated that their inhibition prevented tumor recurrence in our model.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0042252PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3412862PMC
January 2013

Fuzzy tandem repeats containing p53 response elements may define species-specific p53 target genes.

PLoS Genet 2012 Jun 28;8(6):e1002731. Epub 2012 Jun 28.

Institut Curie, Centre de Recherche, Paris, France.

Evolutionary forces that shape regulatory networks remain poorly understood. In mammals, the Rb pathway is a classic example of species-specific gene regulation, as a germline mutation in one Rb allele promotes retinoblastoma in humans, but not in mice. Here we show that p53 transactivates the Retinoblastoma-like 2 (Rbl2) gene to produce p130 in murine, but not human, cells. We found intronic fuzzy tandem repeats containing perfect p53 response elements to be important for this regulation. We next identified two other murine genes regulated by p53 via fuzzy tandem repeats: Ncoa1 and Klhl26. The repeats are poorly conserved in evolution, and the p53-dependent regulation of the murine genes is lost in humans. Our results indicate a role for the rapid evolution of tandem repeats in shaping differences in p53 regulatory networks between mammalian species.
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http://dx.doi.org/10.1371/journal.pgen.1002731DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3386156PMC
June 2012

Thrombospondin-1 triggers cell migration and development of advanced prostate tumors.

Cancer Res 2011 Dec 28;71(24):7649-58. Epub 2011 Oct 28.

CNRS, FRE3239, Université Paris Sud, Villejuif, France.

The antitumor effects of pharmacologic inhibitors of angiogenesis are hampered in patients by the rapid development of tumor resistance, notably through increased invasiveness and accelerated metastasis. Here, we reevaluated the role of the endogenous antiangiogenic thrombospondin 1 (TSP1) in prostate carcinomas in which angiogenesis is an active process. In xenografted tumors, we observed that TSP1 altogether inhibited angiogenesis and fostered tumor development. Our results show that TSP1 is a potent stimulator of prostate tumor cell migration. This effect required CD36, which also mediates TSP1 antiangiogenic activity, and was mimicked by an antiangiogenic TSP1-derived peptide. As suspected for pharmacologic inhibitors of angiogenesis, the TSP1 capacities to increase hypoxia and to trigger cell migration are thus inherently linked. Importantly, although antiangiogenic TSP1 increases hypoxia in vivo, our data show that, in turn, hypoxia induced TSP1, thus generating a vicious circle in prostate tumors. In radical prostatectomy specimens, we found TSP1 expression significantly associated with invasive tumors and with tumors which eventually recurred. TSP1 may thus help select patients at risk of prostate-specific antigen relapse. Together, the data suggest that intratumor disruption of the hypoxic cycle through TSP1 silencing will limit tumor invasion.
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http://dx.doi.org/10.1158/0008-5472.CAN-11-0833DOI Listing
December 2011

Identification of CAD as an androgen receptor interactant and an early marker of prostate tumor recurrence.

FASEB J 2012 Jan 7;26(1):460-7. Epub 2011 Oct 7.

Centre National de la Recherche Scientifique, University of Paris Sud,Villejuif, France.

Markers of prostate tumor recurrence after radical prostatectomy are lacking and highly demanded. The androgen receptor (AR) is a nuclear receptor that plays a pivotal role in normal and cancerous prostate tissue. AR interacts with a number of proteins modulating its stability, localization, and activity. To test the hypothesis that an increased expression of AR partners might foster tumor development, we immunopurified AR partners in human tumors xenografted into mice. One of the identified AR partners was the multifunctional enzyme carbamoyl-phosphate synthetase II, aspartate transcarbamylase, and dihydroorotase (CAD), which catalyzes the 3 initial steps of pyrimidine biosynthesis. We combined experiments in C4-2, LNCaP, 22RV1, and PC3 human prostate cell lines and analysis of frozen radical prostatectomy samples to study the CAD-AR interaction. We show here that in prostate tumor cells, CAD fosters AR translocation into the nucleus and stimulates its transcriptional activity. Notably, in radical prostatectomy specimens, CAD expression was not correlated with proliferation markers, but a higher CAD mRNA level was associated with local tumor extension (P=0.049) and cancer relapse (P=0.017). These results demonstrate an unsuspected function for a key metabolic enzyme and identify CAD as a potential predictive marker of cancer relapse.
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http://dx.doi.org/10.1096/fj.11-191296DOI Listing
January 2012

Systemic delivery and quantification of unformulated interfering RNAs in vivo.

Curr Top Med Chem 2009 ;9(12):1117-29

CNRS, FRE2944, Université Paris-Sud, 7 rue Guy Môquet, 94801 Villejuif, France.

Synthetic small interfering RNAs (siRNAs) open promising new therapeutic perspectives in acute and chronic pathologies. A number of experiments in mice demonstrated the ability of naked siRNAs injected under a normal pressure to trigger gene silencing in vivo, translating into a measurable phenotype. We focus in this review on the information that we can gain from these experiments, and discuss how the specificity of the gene silencing in vivo can be controlled. Because the activity of most drugs increases with the dosing, we are prone to consider that increasing the concentration of siRNAs within cells enhances the efficiency and the duration of the silencing. However, because RNAi is a saturable process, and because increasing the siRNA concentration into cells can induce undesirable side effects, this must be demonstrated. We compare in this review the methods used to quantify and study the biodistribution of siRNAs in living animals, and discuss how these methods can help in designing for each model and each siRNA the most adequate protocol to silence a cognate target gene in vivo.
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http://dx.doi.org/10.2174/156802609789630820DOI Listing
January 2010

SIRNA-directed in vivo silencing of androgen receptor inhibits the growth of castration-resistant prostate carcinomas.

PLoS One 2007 Oct 10;2(10):e1006. Epub 2007 Oct 10.

CNRS, University Paris-Sud, FRE2944, Epigenetics and Cancer, Institut André Lwoff, Villejuif, France.

Background: Prostate carcinomas are initially dependent on androgens, and castration or androgen antagonists inhibit their growth. After some time though, tumors become resistant and recur with a poor prognosis. The majority of resistant tumors still expresses a functional androgen receptor (AR), frequently amplified or mutated.

Methodology/principal Findings: To test the hypothesis that AR is not only expressed, but is still a key therapeutic target in advanced carcinomas, we injected siRNA targeting AR into mice bearing exponentially growing castration-resistant tumors. Quantification of siRNA into tumors and mouse tissues demonstrated their efficient uptake. This uptake silenced AR in the prostate, testes and tumors. AR silencing in tumors strongly inhibited their growth, and importantly, also markedly repressed the VEGF production and angiogenesis.

Conclusions/significance: Our results demonstrate that carcinomas resistant to hormonal manipulations still depend on the expression of the androgen receptor for their development in vivo. The siRNA-directed silencing of AR, which allows targeting overexpressed as well as mutated isoforms, triggers a strong antitumoral and antiangiogenic effect. siRNA-directed silencing of this key gene in advanced and resistant prostate tumors opens promising new therapeutic perspectives and tools.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0001006PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1994591PMC
October 2007

Testosterone regulates FGF-2 expression during testis maturation by an IRES-dependent translational mechanism.

FASEB J 2006 Mar 19;20(3):476-8. Epub 2006 Jan 19.

Institut National de la Santé et de la Recherche Médicale U589, Toulouse, France.

Spermatogenesis is a complex process involving cell proliferation, differentiation, and apoptosis. Fibroblast growth factor 2 (FGF-2) is involved in testicular function, but its role in spermatogenesis has not been fully documented. The control of FGF-2 expression particularly occurs at the translational level, by an internal ribosome entry site (IRES)-dependent mechanism driving the use of alternative initiation codons. To study IRES activity regulation in vivo, we have developed transgenic mice expressing a bicistronic construct coding for two luciferase genes. Here, we show that the FGF-2 IRES is age-dependently activated in mouse testis, whereas EMCV and c-myc IRESs are not. Real-time PCR confirms that this regulation is translational. By using immunohistological techniques, we demonstrate that FGF-2 IRES stimulation occurs in adult, but not in immature, type-A spermatogonias. This is correlated with activation of endogenous FGF-2 expression in spermatogonia; whereas FGF-2 mRNA transcription is known to decrease in adult testis. Interestingly, the FGF-2 IRES activation is triggered by testosterone and is partially inhibited by siRNA directed against the androgen receptor. Two-dimensional analysis of proteins bound to the FGF-2 mRNA 5'UTR after UV cross-linking reveals that testosterone treatment correlates with the binding of several proteins. These data suggest a paracrine loop where IRES-dependent FGF-2 expression, stimulated by Sertoli cells in response to testosterone produced by Leydig cells, would in turn activate Leydig function and testosterone production. In addition, nuclear FGF-2 isoforms could be involved in an intracrine function of FGF-2 in the start of spermatogenesis, mitosis, or meiosis initiation. This report demonstrates that mRNA translation regulation by an IRES-dependent mechanism participates in a physiological process.
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http://dx.doi.org/10.1096/fj.04-3314fjeDOI Listing
March 2006
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