Publications by authors named "Sophie Gad"

31 Publications

Integrative analysis of dysregulated microRNAs and mRNAs in multiple recurrent synchronized renal tumors from patients with von Hippel-Lindau disease.

Int J Oncol 2018 Oct 19;53(4):1455-1468. Epub 2018 Jul 19.

Oncogenetics Laboratory, EPHE, PSL Research University, 75014 Paris, France.

Von Hippel-Lindau (VHL) disease is a rare autosomal dominant syndrome that is the main cause of inherited clear-cell renal cell carcinoma (ccRCC), which generally occurs in the form of multiple recurrent synchronized tumors. Affected patients are carriers of a germline mutation in the VHL tumor suppressor gene. Somatic mutations of this gene are also found in sporadic ccRCC and numerous pan-genomic studies have reported a dysregulation of microRNA (miRNA) expression in these sporadic tumors. In order to investigate the molecular mechanisms underlying the pathogenesis of VHL-associated ccRCC, particularly in the context of multiple tumors, the present study characterized the mRNA and miRNA transcriptome through an integrative analysis compared with sporadic renal tumors. In the present study, two series of ccRCC samples were used. The first set consisted of several samples from different tumors occurring in the same patient, for two independent patients affected with VHL disease. The second set consisted of 12 VHL-associated tumors and 22 sporadic ccRCC tumors compared with a pool of normal renal tissue. For each sample series, an expression analysis of miRNAs and mRNAs was conducted using microarrays. The results indicated that multiple tumors within the kidney of a patient with VHL disease featured a similar pattern of miRNA and gene expression. In addition, the expression levels of miRNA were able to distinguish VHL-associated tumors from sporadic ccRCC, and it was identified that 103 miRNAs and 2,474 genes were differentially expressed in the ccRCC series compared with in normal renal tissue. The majority of dysregulated genes were implicated in 'immunity' and 'metabolism' pathways. Taken together, these results allow a better understanding of the occurrence of ccRCC in patients with VHL disease, by providing insights into dysregulated miRNA and mRNA. In the set of patients with VHL disease, there were few differences in miRNA and mRNA expression, thus indicating a similar molecular evolution of these synchronous tumors and suggesting that the same molecular mechanisms underlie the pathogenesis of these hereditary tumors.
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http://dx.doi.org/10.3892/ijo.2018.4490DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6086628PMC
October 2018

Identification of a new exon and complex splicing alterations in familial erythrocytosis or von Hippel-Lindau disease.

Blood 2018 08 11;132(5):469-483. Epub 2018 Jun 11.

École Pratique des Hautes Études, PSL Research University, Paris, France.

Chuvash polycythemia is an autosomal recessive form of erythrocytosis associated with a homozygous p.Arg200Trp mutation in the von Hippel-Lindau () gene. Since this discovery, additional mutations have been identified in patients with congenital erythrocytosis, in a homozygous or compound-heterozygous state. is a major tumor suppressor gene, mutations in which were first described in patients presenting with VHL disease, which is characterized by the development of highly vascularized tumors. Here, we identify a new cryptic exon (termed E1') deep in intron 1 that is naturally expressed in many tissues. More importantly, we identify mutations in E1' in 7 families with erythrocytosis (1 homozygous case and 6 compound-heterozygous cases with a mutation in E1' in addition to a mutation in coding sequences) and in 1 large family with typical VHL disease but without any alteration in the other exons. In this study, we show that the mutations induced a dysregulation of splicing with excessive retention of E1' and were associated with a downregulation of VHL protein expression. In addition, we demonstrate a pathogenic role for synonymous mutations in exon 2 that altered splicing through E2-skipping in 5 families with erythrocytosis or VHL disease. In all the studied cases, the mutations differentially affected splicing, correlating with phenotype severity. This study demonstrates that cryptic exon retention and exon skipping are new alterations and reveals a novel complex splicing regulation of the gene. These findings open new avenues for diagnosis and research regarding the VHL-related hypoxia-signaling pathway.
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http://dx.doi.org/10.1182/blood-2018-03-838235DOI Listing
August 2018

Renal Cell Carcinoma Programmed Death-ligand 1, a New Direct Target of Hypoxia-inducible Factor-2 Alpha, is Regulated by von Hippel-Lindau Gene Mutation Status.

Eur Urol 2016 10 23;70(4):623-632. Epub 2015 Dec 23.

INSERM (Institut National de la Santé et de la Recherche Médicale) UMR1186, Laboratory Integrative Tumor Immunology and Genetic Oncology, Villejuif, France; INSERM, Gustave Roussy, Univ. Paris-Sud, Université Paris-Saclay, Villejuif, F-94805, France. Electronic address:

Background: Clear cell renal cell carcinomas (ccRCC) frequently display a loss of function of the von Hippel-Lindau (VHL) gene.

Objective: To elucidate the putative relationship between VHL mutation status and immune checkpoint ligand programmed death-ligand 1 (PD-L1) expression.

Design, Setting, And Participants: A series of 32 renal tumors composed of 11 VHL tumor-associated and 21 sporadic RCCs were used to evaluate PD-L1 expression levels after sequencing of the three exons and exon-intron junctions of the VHL gene. The 786-O, A498, and RCC4 cell lines were used to investigate the mechanisms of PD-L1 regulation.

Outcome Measurements And Statistical Analysis: Fisher's exact test was used for VHL mutation and Kruskal-Wallis test for PD-L1 expression. If no covariate accounted for the association of VHL and PD-L1, then a Kruskal-Wallis test was used; otherwise Cochran-Mantel-Haenzsel test was used. We also used the Fligner-Policello test to compare two medians when the distributions had different dispersions.

Results And Limitations: We demonstrated that tumors from ccRCC patients with VHL biallelic inactivation (ie, loss of function) display a significant increase in PD-L1 expression compared with ccRCC tumors carrying one VHL wild-type allele. Using the inducible VHL 786-O-derived cell lines with varying hypoxia-inducible factor-2 alpha (HIF-2α) stabilization levels, we showed that PD-L1 expression levels positively correlate with VHL mutation and HIF-2α expression. Targeting HIF-2α decreased PD-L1, while HIF-2α overexpression increased PD-L1 mRNA and protein levels in ccRCC cells. Interestingly, chromatin immunoprecipitation and luciferase assays revealed a direct binding of HIF-2α to a transcriptionally active hypoxia-response element in the human PD-L1 proximal promoter in 786-O cells.

Conclusions: Our work provides the first evidence that VHL mutations positively correlate with PD-L1 expression in ccRCC and may influence the response to ccRCC anti-PD-L1/PD-1 immunotherapy.

Patient Summary: We investigated the relationship between von Hippel-Lindau mutations and programmed death-ligand 1 expression. We demonstrated that von Hippel-Lindau mutation status significantly correlated with programmed death-ligand 1 expression in clear cell renal cell carcinomas.
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http://dx.doi.org/10.1016/j.eururo.2015.11.029DOI Listing
October 2016

Fumarate Hydratase-deficient Cell Line NCCFH1 as a New In Vitro Model of Hereditary Papillary Renal Cell Carcinoma Type 2.

Anticancer Res 2015 Dec;35(12):6639-53

Division of Medical Sciences, National Cancer Centre Singapore, Singapore, Republic of Singapore Division of Cancer and Stem Cell Biology, Duke-NUS Graduate Medical School, Singapore, Republic of Singapore

Background/aim: Hereditary leiomyomatosis and renal cell carcinoma (HLRCC) is a rare autosomal dominant disorder characterized by fumarate hydratase (FH) gene mutation. It is associated with the development of very aggressive kidney tumors, characterized by early onset and high metastatic potential, and has no effective therapy. The aim of the study was to establish a new preclinical platform for investigating morphogenetic and metabolic features, and alternative therapy of metastatic hereditary papillary renal cell carcinoma type 2 (PRCC2).

Materials And Methods: Fresh cells were collected from pleural fluid of a patient with metastatic hereditary PRCC2. Morphogenetic and functional characteristics were evaluated via microscopy, FH gene sequencing analysis, real-time polymerase chaine reaction and enzymatic activity measurement. We performed bioenergetic analysis, gene-expression profiling, and cell viability assay with 19 anti-neoplastic drugs.

Results: We established a new in vitro model of hereditary PRCC2 - the NCCFH1 cell line. The cell line possesses a c.1162 delA - p.Thr375fs frameshift mutation in the FH gene. Our findings indicate severe attenuation of oxidative phosphorylation and glucose-dependent growth of NCCFH1 cells that is consistent with the Warburg effect. Furthermore, gene-expression profiling identified that the most prominent molecular features reflected a high level of apoptosis, cell adhesion, and cell signaling. Drug screening revealed a marked sensitivity of FH(-/-) cells to mitoxantrone, epirubicin, topotecan and a high sensitivity to bortezomib.

Conclusion: We demonstrated that the NCCFH1 cell line is a very interesting preclinical model for studying the metabolic features and testing new therapies for hereditary PRCC2, while bortezomib may be a potential efficient therapeutic option.
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December 2015

Isolation and characterization of renal cancer stem cells from patient-derived xenografts.

Oncotarget 2016 Mar;7(13):15507-24

INSERM U 1186, Equipe labellisée Ligue Contre le Cancer, Gustave Roussy Campus, Villejuif, France.

As rapidly developing patient-derived xenografts (PDX) could represent potential sources of cancer stem cells (CSC), we selected and characterized non-cultured PDX cell suspensions from four different renal carcinomas (RCC). Only the cell suspensions from the serial xenografts (PDX-1 and PDX-2) of an undifferentiated RCC (RCC-41) adapted to the selective CSC medium. The cell suspension derived from the original tumor specimen (RCC-41-P-0) did not adapt to the selective medium and strongly expressed CSC-like markers (CD133 and CD105) together with the non-CSC tumor marker E-cadherin. In comparison, PDX-1 and PDX-2 cells exhibited evolution in their phenotype since PDX-1 cells were CD133high/CD105-/Ecadlow and PDX-2 cells were CD133low/CD105-/Ecad-. Both PDX subsets expressed additional stem cell markers (CD146/CD29/OCT4/NANOG/Nestin) but still contained non-CSC tumor cells. Therefore, using different cell sorting strategies, we characterized 3 different putative CSC subsets (RCC-41-PDX-1/CD132+, RCC-41-PDX-2/CD133-/EpCAMlow and RCC-41-PDX-2/CD133+/EpCAMbright). In addition, transcriptomic analysis showed that RCC-41-PDX-2/CD133- over-expressed the pluripotency gene ERBB4, while RCC-41-PDX-2/CD133+ over-expressed several tumor suppressor genes. These three CSC subsets displayed ALDH activity, formed serial spheroids and developed serial tumors in SCID mice, although RCC-41-PDX-1/CD132+ and RCC-41-PDX-2/CD133+ displayed less efficiently the above CSC properties. RCC-41-PDX-1/CD132+ tumors showed vessels of human origin with CSC displaying peri-vascular distribution. By contrast, RCC-41-PDX-2 originated tumors exhibiting only vessels of mouse origin without CSC peri-vascular distribution.Altogether, our results indicate that PDX murine microenvironment promotes a continuous redesign of CSC phenotype, unmasking CSC subsets potentially present in a single RCC or generating ex novo different CSC-like subsets.
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http://dx.doi.org/10.18632/oncotarget.6266DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4941257PMC
March 2016

A germline mutation in PBRM1 predisposes to renal cell carcinoma.

J Med Genet 2015 Jun 24;52(6):426-30. Epub 2015 Apr 24.

Ecole Pratique des Hautes Etudes, Paris, France Laboratoire de Génétique Oncologique EPHE, INSERM U753, Villejuif, France Faculté de Médecine Université Paris-Sud, Le Kremlin-Bicêtre, France.

Background: Many cases of familial renal cell carcinoma (RCC) remain unexplained by mutations in the known predisposing genes or shared environmental factors. There are therefore additional, still unidentified genes involved in familial RCC. PBRM1 is a tumour suppressor gene and somatic mutations are found in 30-45% of sporadic clear cell (cc) RCC.

Methods: We selected 35 unrelated patients with unexplained personal history of ccRCC and at least one affected first-degree relative, and sequenced the PBRM1 gene.

Results: A germline frameshift mutation (c.3998_4005del [p.Asp1333Glyfs]) was found in one patient. The patient's mother, his sister and one niece also had ccRCC. The mutation co-segregated with the disease as the three affected relatives were carriers, while an unaffected sister was not, according with autosomal-dominant transmission. Somatic studies supported these findings, as we observed both loss of heterozygosity for the mutation and loss of protein expression in renal tumours.

Conclusions: We show for the first time that an inherited mutation in PBRM1 predisposes to RCC. International studies are necessary to estimate the contribution of PBRM1 to RCC susceptibility, estimate penetrance and then integrate the gene into routine clinical practice.
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http://dx.doi.org/10.1136/jmedgenet-2014-102912DOI Listing
June 2015

Genetic evidence of a precisely tuned dysregulation in the hypoxia signaling pathway during oncogenesis.

Cancer Res 2014 Nov 4;74(22):6554-64. Epub 2014 Nov 4.

Laboratoire de Génétique Oncologique de l'Ecole Pratique des Hautes Etudes (EPHE), Villejuif, France. Unité Mixte de Recherche (UMR) INSERM U892, CNRS 6299, Centre de Recherche en Cancérologie Nantes/Angers (CRCNA), Université de Nantes, Nantes, France.

The classic model of tumor suppression implies that malignant transformation requires full "two-hit" inactivation of a tumor-suppressor gene. However, more recent work in mice has led to the proposal of a "continuum" model that involves more fluid concepts such as gene dosage-sensitivity and tissue specificity. Mutations in the tumor-suppressor gene von Hippel-Lindau (VHL) are associated with a complex spectrum of conditions. Homozygotes or compound heterozygotes for the R200W germline mutation in VHL have Chuvash polycythemia, whereas heterozygous carriers are free of disease. Individuals with classic, heterozygous VHL mutations have VHL disease and are at high risk of multiple tumors (e.g., CNS hemangioblastomas, pheochromocytoma, and renal cell carcinoma). We report here an atypical family bearing two VHL gene mutations in cis (R200W and R161Q), together with phenotypic analysis, structural modeling, functional, and transcriptomic studies of these mutants in comparison with classical mutants involved in the different VHL phenotypes. We demonstrate that the complex pattern of disease manifestations observed in VHL syndrome is perfectly correlated with a gradient of VHL protein (pVHL) dysfunction in hypoxia signaling pathways. Thus, by studying naturally occurring familial mutations, our work validates in humans the "continuum" model of tumor suppression.
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http://dx.doi.org/10.1158/0008-5472.CAN-14-1161DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5555745PMC
November 2014

Case Report: Expanding the tumour spectrum associated with the Birt-Hogg-Dubé cancer susceptibility syndrome.

F1000Res 2014 11;3:159. Epub 2014 Jul 11.

Centre Expert National Cancers Rares PREDIR, Hôpital Bicêtre, AP-HP, Le Kremlin Bicêtre, 94275, France.

Patients with the Birt-Hogg-Dubé cancer susceptibility syndrome are at high risk of developing renal cell carcinoma, pulmonary cysts and pneumothorax, and skin lesions called fibrofolliculomas. Here we report the case of a Birt-Hogg-Dubé patient with a primary clear cell carcinoma of the thyroid (a very rare type of thyroid cancer), and FLCN loss of heterozygosity within the tumour, providing molecular evidence for this association. Our findings expand the tumour spectrum associated with this syndrome. It is paramount to identify individuals with Birt-Hogg-Dubé so that they, and subsequently their affected relatives, can benefit from tailored cancer screening and prevention.
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http://dx.doi.org/10.12688/f1000research.4205.1DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4168750PMC
September 2014

MET is a potential target across all papillary renal cell carcinomas: result from a large molecular study of pRCC with CGH array and matching gene expression array.

Clin Cancer Res 2014 Jul 21;20(13):3411-21. Epub 2014 Mar 21.

Authors' Affiliations: Department of Cancer Medicine, Institut Gustave Roussy, Villejuif, France; INSERM U753, IGR, Villejuif, France;

Purpose: Papillary renal cell carcinomas (pRCC) are the most common nonclear cell RCC subtype. Germline mutations of the MET oncogene at 7q31 have been detected in patients with hereditary type I pRCC and in 13% of sporadic type I pRCC. Recent report of MET inhibition strengthened the role of c-Met inhibition across pRCC.

Experimental Design: We collected 220 frozen samples of sporadic pRCC through the French RCC Network and quality controlled for percentage of malignant cells >70%. Gene expression was assessed on 98 pRCC using human whole-genome Agilent 8 × 60K arrays. Copy number alterations were analyzed using Agilent Human 2 × 400K and 4× 180K array for type II pRCC and comparative genomic microarray analysis method for type I pRCC. MET gene sequencing was performed on type I pRCC.

Results: MET expression level was high across all pRCC. We identified copy number alterations (gain) in 46% of type II pRCC and in 81% of type I pRCC. Correlation between DNA copy number alterations and mRNA expression level was highly significant. Eleven somatic mutations of MET gene were identified amongst 51 type I pRCC (21.6%), including 4 new mutations. We validated LRRK2 cokinase as highly correlated to MET expression.

Conclusion: The present report expands the role of MET activation as a potential target across all pRCC subtypes. These data support investigating MET inhibitors in pRCC in correlation with MET activation status.
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http://dx.doi.org/10.1158/1078-0432.CCR-13-2173DOI Listing
July 2014

Germline BAP1 mutations predispose to renal cell carcinomas.

Am J Hum Genet 2013 Jun 16;92(6):974-80. Epub 2013 May 16.

Institut Curie, Inserm U830, Paris 75248, France.

The genetic cause of some familial nonsyndromic renal cell carcinomas (RCC) defined by at least two affected first-degree relatives is unknown. By combining whole-exome sequencing and tumor profiling in a family prone to cases of RCC, we identified a germline BAP1 mutation c.277A>G (p.Thr93Ala) as the probable genetic basis of RCC predisposition. This mutation segregated with all four RCC-affected relatives. Furthermore, BAP1 was found to be inactivated in RCC-affected individuals from this family. No BAP1 mutations were identified in 32 familial cases presenting with only RCC. We then screened for germline BAP1 deleterious mutations in familial aggregations of cancers within the spectrum of the recently described BAP1-associated tumor predisposition syndrome, including uveal melanoma, malignant pleural mesothelioma, and cutaneous melanoma. Among the 11 families that included individuals identified as carrying germline deleterious BAP1 mutations, 6 families presented with 9 RCC-affected individuals, demonstrating a significantly increased risk for RCC. This strongly argues that RCC belongs to the BAP1 syndrome and that BAP1 is a RCC-predisposition gene.
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http://dx.doi.org/10.1016/j.ajhg.2013.04.012DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3675229PMC
June 2013

Telomere crisis in kidney epithelial cells promotes the acquisition of a microRNA signature retrieved in aggressive renal cell carcinomas.

Carcinogenesis 2013 May 27;34(5):1173-80. Epub 2013 Jan 27.

UMR3244, Telomeres and Cancer Laboratory, Institut Curie, 26 rue d'Ulm, Paris 75248, France.

Telomere shortening is a major source of chromosome instability (CIN) at early stages during carcinogenesis. However, the mechanisms through which telomere-driven CIN (T-CIN) contributes to the acquisition of tumor phenotypes remain uncharacterized. We discovered that human epithelial kidney cells undergoing T-CIN display massive microRNA (miR) expression changes that are not related to local losses or gains. This widespread miR deregulation encompasses a miR-200-dependent epithelial-to-mesenchymal transition (EMT) that confers to immortalized pre-tumoral cells phenotypic traits of metastatic potential. Remarkably, a miR signature of these cells, comprising a downregulation of miRs with conserved expression in kidney, was retrieved in poorly differentiated aggressive renal cell carcinomas. Our results reveal an unanticipated connection between telomere crisis and the activation of the EMT program that occurs at pre-invasive stages of epithelial cancers, through mechanisms that involve miR deregulation. Thus, this study provides a new rational into how telomere instability contributes to the acquisition of the malignant phenotype.
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http://dx.doi.org/10.1093/carcin/bgt029DOI Listing
May 2013

Von Hippel-Lindau: how a rare disease illuminates cancer biology.

Semin Cancer Biol 2013 Feb 30;23(1):26-37. Epub 2012 May 30.

Laboratoire de Génétique Oncologique EPHE, INSERM U743, Faculté de Médecine Paris-Sud, 94276 Le Kremlin-Bicêtre et Institut de cancérologie Gustave Roussy, 94800 Villejuif, France.

Von Hippel-Lindau (VHL) disease is a rare autosomal dominant syndrome (1/36,000 live births) with highly penetrance that predispose to the development of a panel of highly vascularized tumors (model of tumoral angiogenesis). Main manifestations include central nervous system (CNS) and retinal haemangioblastomas, endolymphatic sac tumors, clear-cell renal cell carcinomas (RCC), phaeochromocytomas and pancreatic neuroendocrine tumors. RCC has become the first potential cause of mortality and VHL disease is the main cause of inherited RCC. The disease is caused by germline mutations in the VHL tumor-suppressor gene that plays a major role in regulation of the oxygen-sensing pathway by targeting the hypoxia-inducible factor HIF for degradation in proteasome. VHL has also major HIF-independent functions, specially in regulation of primary cilium, extracellular matrix and apoptosis. Somatic inactivation of the VHL gene is the main molecular event in most sporadic RCC and the treatment of advanced RCC has been revolutionized by targeted therapy with drugs that block angiogenesis. These drugs are now in first line in metastatic sporadic RCC and have shown promising results for RCC, pancreatic neuroendocrine tumors and malignant pheochromocytomas in VHL patients.
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http://dx.doi.org/10.1016/j.semcancer.2012.05.005DOI Listing
February 2013

A SUMOylation-defective MITF germline mutation predisposes to melanoma and renal carcinoma.

Authors:
Corine Bertolotto Fabienne Lesueur Sandy Giuliano Thomas Strub Mahaut de Lichy Karine Bille Philippe Dessen Benoit d'Hayer Hamida Mohamdi Audrey Remenieras Eve Maubec Arnaud de la Fouchardière Vincent Molinié Pierre Vabres Stéphane Dalle Nicolas Poulalhon Tanguy Martin-Denavit Luc Thomas Pascale Andry-Benzaquen Nicolas Dupin Françoise Boitier Annick Rossi Jean-Luc Perrot Bruno Labeille Caroline Robert Bernard Escudier Olivier Caron Laurence Brugières Simon Saule Betty Gardie Sophie Gad Stéphane Richard Jérôme Couturier Bin Tean Teh Paola Ghiorzo Lorenza Pastorino Susana Puig Celia Badenas Hakan Olsson Christian Ingvar Etienne Rouleau Rosette Lidereau Philippe Bahadoran Philippe Vielh Eve Corda Hélène Blanché Diana Zelenika Pilar Galan François Aubin Bertrand Bachollet Céline Becuwe Pascaline Berthet Yves Jean Bignon Valérie Bonadona Jean-Louis Bonafe Marie-Noëlle Bonnet-Dupeyron Fréderic Cambazard Jacqueline Chevrant-Breton Isabelle Coupier Sophie Dalac Liliane Demange Michel d'Incan Catherine Dugast Laurence Faivre Lynda Vincent-Fétita Marion Gauthier-Villars Brigitte Gilbert Florent Grange Jean-Jacques Grob Philippe Humbert Nicolas Janin Pascal Joly Delphine Kerob Christine Lasset Dominique Leroux Julien Levang Jean-Marc Limacher Cristina Livideanu Michel Longy Alain Lortholary Dominique Stoppa-Lyonnet Sandrine Mansard Ludovic Mansuy Karine Marrou Christine Matéus Christine Maugard Nicolas Meyer Catherine Nogues Pierre Souteyrand Laurence Venat-Bouvet Hélène Zattara Valérie Chaudru Gilbert M Lenoir Mark Lathrop Irwin Davidson Marie-Françoise Avril Florence Demenais Robert Ballotti Brigitte Bressac-de Paillerets

Nature 2011 Oct 19;480(7375):94-8. Epub 2011 Oct 19.

1] INSERM, U895 (équipe 1), Equipe labélisée Ligue Contre le Cancer, C3M, 06204 Nice, France [2] Université of Nice Sophia-Antipolis, UFR Médecine, 06204 Nice, France [3] Centre Hospitalier Universitaire de Nice, Service de Dermatologie, 06204 Nice, France [4].

So far, no common environmental and/or phenotypic factor has been associated with melanoma and renal cell carcinoma (RCC). The known risk factors for melanoma include sun exposure, pigmentation and nevus phenotypes; risk factors associated with RCC include smoking, obesity and hypertension. A recent study of coexisting melanoma and RCC in the same patients supports a genetic predisposition underlying the association between these two cancers. The microphthalmia-associated transcription factor (MITF) has been proposed to act as a melanoma oncogene; it also stimulates the transcription of hypoxia inducible factor (HIF1A), the pathway of which is targeted by kidney cancer susceptibility genes. We therefore proposed that MITF might have a role in conferring a genetic predisposition to co-occurring melanoma and RCC. Here we identify a germline missense substitution in MITF (Mi-E318K) that occurred at a significantly higher frequency in genetically enriched patients affected with melanoma, RCC or both cancers, when compared with controls. Overall, Mi-E318K carriers had a higher than fivefold increased risk of developing melanoma, RCC or both cancers. Codon 318 is located in a small-ubiquitin-like modifier (SUMO) consensus site (ΨKXE) and Mi-E318K severely impaired SUMOylation of MITF. Mi-E318K enhanced MITF protein binding to the HIF1A promoter and increased its transcriptional activity compared to wild-type MITF. Further, we observed a global increase in Mi-E318K-occupied loci. In an RCC cell line, gene expression profiling identified a Mi-E318K signature related to cell growth, proliferation and inflammation. Lastly, the mutant protein enhanced melanocytic and renal cell clonogenicity, migration and invasion, consistent with a gain-of-function role in tumorigenesis. Our data provide insights into the link between SUMOylation, transcription and cancer.
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http://dx.doi.org/10.1038/nature10539DOI Listing
October 2011

Distinct deregulation of the hypoxia inducible factor by PHD2 mutants identified in germline DNA of patients with polycythemia.

Haematologica 2012 Jan 20;97(1):9-14. Epub 2011 Sep 20.

Villejuif et Faculté de Médecine Paris-Sud, Génétique Oncologique EPHE, INSERM U753, Institut de Cancérologie Gustave Roussy, Le Kremlin-Bicêtre, France.

Background: Congenital secondary erythrocytoses are due to deregulation of hypoxia inducible factor resulting in overproduction of erythropoietin. The most common germline mutation identified in the hypoxia signaling pathway is the Arginine 200-Tryptophan mutant of the von Hippel-Lindau tumor suppressor gene, resulting in Chuvash polycythemia. This mutant displays a weak deficiency in hypoxia inducible factor α regulation and does not promote tumorigenesis. Other von Hippel-Lindau mutants with more deleterious effects are responsible for von Hippel-Lindau disease, which is characterized by the development of multiple tumors. Recently, a few mutations in gene for the prolyl hydroxylase domain 2 protein (PHD2) have been reported in cases of congenital erythrocytosis not associated with tumor formation with the exception of one patient with a recurrent extra-adrenal paraganglioma.

Design And Methods: Five PHD2 variants, four of which were novel, were identified in patients with erythrocytosis. These PHD2 variants were functionally analyzed and compared with the PHD2 mutant previously identified in a patient with polycythemia and paraganglioma. The capacity of PHD2 to regulate the activity, stability and hydroxylation of hypoxia inducible factor α was assessed using hypoxia-inducible reporter gene, one-hybrid and in vitro hydroxylation assays, respectively.

Results: This functional comparative study showed that two categories of PHD2 mutants could be distinguished: one category with a weak deficiency in hypoxia inducible factor α regulation and a second one with a deleterious effect; the mutant implicated in tumor occurrence belongs to the second category.

Conclusions: As observed with germline von Hippel-Lindau mutations, there are functional differences between the PHD2 mutants with regards to hypoxia inducible factor regulation. PHD2 mutation carriers do, therefore, need careful medical follow-up, since some mutations must be considered as potential candidates for tumor predisposition.
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http://dx.doi.org/10.3324/haematol.2011.044644DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3248925PMC
January 2012

Birt-Hogg-Dubé renal tumors are genetically distinct from other renal neoplasias and are associated with up-regulation of mitochondrial gene expression.

BMC Med Genomics 2010 Dec 16;3:59. Epub 2010 Dec 16.

Laboratory of Computational Biology, Van Andel Research Institute, Grand Rapids, MI, USA.

Background: Germline mutations in the folliculin (FLCN) gene are associated with the development of Birt-Hogg-Dubé syndrome (BHDS), a disease characterized by papular skin lesions, a high occurrence of spontaneous pneumothorax, and the development of renal neoplasias. The majority of renal tumors that arise in BHDS-affected individuals are histologically similar to sporadic chromophobe renal cell carcinoma (RCC) and sporadic renal oncocytoma. However, most sporadic tumors lack FLCN mutations and the extent to which the BHDS-derived renal tumors share genetic defects associated with the sporadic tumors has not been well studied.

Methods: BHDS individuals were identified symptomatically and FLCN mutations were confirmed by DNA sequencing. Comparative gene expression profiling analyses were carried out on renal tumors isolated from individuals afflicted with BHDS and a panel of sporadic renal tumors of different subtypes using discriminate and clustering approaches. qRT-PCR was used to confirm selected results of the gene expression analyses. We further analyzed differentially expressed genes using gene set enrichment analysis and pathway analysis approaches. Pathway analysis results were confirmed by generation of independent pathway signatures and application to additional datasets.

Results: Renal tumors isolated from individuals with BHDS showed distinct gene expression and cytogenetic characteristics from sporadic renal oncocytoma and chromophobe RCC. The most prominent molecular feature of BHDS-derived kidney tumors was high expression of mitochondria-and oxidative phosphorylation (OXPHOS)-associated genes. This mitochondria expression phenotype was associated with deregulation of the PGC-1α-TFAM signaling axis. Loss of FLCN expression across various tumor types is also associated with increased nuclear mitochondrial gene expression.

Conclusions: Our results support a genetic distinction between BHDS-associated tumors and other renal neoplasias. In addition, deregulation of the PGC-1α-TFAM signaling axis is most pronounced in renal tumors that harbor FLCN mutations and in tumors from other organs that have relatively low expression of FLCN. These results are consistent with the recently discovered interaction between FLCN and AMPK and support a model in which FLCN is a regulator of mitochondrial function.
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http://dx.doi.org/10.1186/1755-8794-3-59DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3012009PMC
December 2010

The ancient mammalian KRAB zinc finger gene cluster on human chromosome 8q24.3 illustrates principles of C2H2 zinc finger evolution associated with unique expression profiles in human tissues.

BMC Genomics 2010 Mar 26;11:206. Epub 2010 Mar 26.

Institute of Immunology, University of Rostock, Schillingallee 70, 18055 Rostock, Germany.

Background: Expansion of multi-C2H2 domain zinc finger (ZNF) genes, including the Krüppel-associated box (KRAB) subfamily, paralleled the evolution of tetrapodes, particularly in mammalian lineages. Advances in their cataloging and characterization suggest that the functions of the KRAB-ZNF gene family contributed to mammalian speciation.

Results: Here, we characterized the human 8q24.3 ZNF cluster on the genomic, the phylogenetic, the structural and the transcriptome level. Six (ZNF7, ZNF34, ZNF250, ZNF251, ZNF252, ZNF517) of the seven locus members contain exons encoding KRAB domains, one (ZNF16) does not. They form a paralog group in which the encoded KRAB and ZNF protein domains generally share more similarities with each other than with other members of the human ZNF superfamily. The closest relatives with respect to their DNA-binding domain were ZNF7 and ZNF251. The analysis of orthologs in therian mammalian species revealed strong conservation and purifying selection of the KRAB-A and zinc finger domains. These findings underscore structural/functional constraints during evolution. Gene losses in the murine lineage (ZNF16, ZNF34, ZNF252, ZNF517) and potential protein truncations in primates (ZNF252) illustrate ongoing speciation processes. Tissue expression profiling by quantitative real-time PCR showed similar but distinct patterns for all tested ZNF genes with the most prominent expression in fetal brain. Based on accompanying expression signatures in twenty-six other human tissues ZNF34 and ZNF250 revealed the closest expression profiles. Together, the 8q24.3 ZNF genes can be assigned to a cerebellum, a testis or a prostate/thyroid subgroup. These results are consistent with potential functions of the ZNF genes in morphogenesis and differentiation. Promoter regions of the seven 8q24.3 ZNF genes display common characteristics like missing TATA-box, CpG island-association and transcription factor binding site (TFBS) modules. Common TFBS modules partly explain the observed expression pattern similarities.

Conclusions: The ZNF genes at human 8q24.3 form a relatively old mammalian paralog group conserved in eutherian mammals for at least 130 million years. The members persisted after initial duplications by undergoing subfunctionalizations in their expression patterns and target site recognition. KRAB-ZNF mediated repression of transcription might have shaped organogenesis in mammalian ontogeny.
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http://dx.doi.org/10.1186/1471-2164-11-206DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2865497PMC
March 2010

PHD2 mutation and congenital erythrocytosis with paraganglioma.

N Engl J Med 2008 Dec;359(25):2685-92

Génétique Oncologique, Ecole Pratique des Hautes Etudes and Centre National de la Recherche Scientifique (FRE 2939), Institut de Cancérologie Gustave Roussy, Villejuif, France.

Prolyl hydroxylase domain (PHD) proteins play a major role in regulating the hypoxia-inducible factor (HIF) that induces expression of genes involved in angiogenesis, erythropoiesis, and cell metabolism, proliferation, and survival. Germ-line mutations in the prolyl hydroxylase domain 2 gene (PHD2) have been reported in patients with familial erythrocytosis but not in association with tumors. We describe a patient with erythrocytosis and recurrent paraganglioma who carries a newly discovered PHD2 mutation. This mutation affects PHD2 function and stabilizes HIF-alpha proteins. In addition, we demonstrate loss of heterozygosity of PHD2 in the tumor, suggesting that PHD2 could be a tumor-suppressor gene.
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http://dx.doi.org/10.1056/NEJMoa0806277DOI Listing
December 2008

Familial non-VHL clear cell (conventional) renal cell carcinoma: clinical features, segregation analysis, and mutation analysis of FLCN.

Clin Cancer Res 2008 Sep;14(18):5925-30

Cancer Research UK Renal Molecular Oncology Group and Department of Medical and Molecular Genetics, University of Birmingham and West Midlands Regional Genetics Service, Birmingham Women's Hospital, United Kingdom.

Purpose: Familial renal cell carcinoma (RCC) is genetically heterogeneous. The most common histopathologic subtype of sporadic and familial RCC is clear cell (cRCC) and von Hippel-Lindau (VHL) disease is the most common cause of inherited cRCC. Familial cRCC may also be associated with chromosome 3 translocations and has recently been described in patients with Birt-Hogg-Dube (BHD) syndrome, caused by germline FLCN mutation. Fewer than 20 kindreds with familial cRCC without VHL disease or a constitutional translocation have been described. The purpose of this investigation was to define the clinical and genetic features of familial non-VHL cRCC (FcRCC) and to evaluate whether unrecognized BHD syndrome might be present in patients with apparent nonsyndromic RCC susceptibility.

Experimental Design: We analyzed the clinical features of, and undertook segregation analysis in, 60 kindreds containing two or more cases of RCC (at least one confirmed case of cRCC) and no evidence of an RCC susceptibility syndrome. We also undertook FLCN analysis to evaluate whether unrecognized BHD syndrome might be present in 69 patients with apparent nonsyndromic RCC susceptibility.

Results: FcRCC was characterized by an earlier age at onset than sporadic cases and more frequent occurrence of bilateral or multicentric tumors. Segregation analysis showed autosomal dominant inheritance with sex- and age-dependent penetrance. A germline FLCN mutation was detected in 3 of 69 (4.3%) patients with apparent nonsyndromic RCC susceptibility.

Conclusions: We describe the clinical and genetic features of the largest series of FcRCC and recommend these patients be offered FLCN analysis, in addition to constitutional cytogenetic and VHL analysis.
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http://dx.doi.org/10.1158/1078-0432.CCR-08-0608DOI Listing
September 2008

Trichloroethylene exposure and somatic mutations of the VHL gene in patients with Renal Cell Carcinoma.

J Occup Med Toxicol 2007 Nov 12;2:13. Epub 2007 Nov 12.

Laboratoire de Génétique Oncologique EPHE, Faculté de Médecine Paris-Sud, Le Kremlin-Bicêtre 94275 Le Kremlin-Bicêtre Cedex, France.

Background: We investigated the association between exposure to trichloroethylene (TCE) and mutations in the von Hippel-Lindau (VHL) gene and the subsequent risk for renal cell carcinoma (RCC).

Methods: Cases were recruited from a case-control study previously carried out in France that suggested an association between exposures to high levels of TCE and increased risk of RCC. From 87 cases of RCC recruited for the epidemiological study, 69 were included in the present study. All samples were evaluated by a pathologist in order to identify the histological subtype and then be able to focus on clear cell RCC. The majority of the tumour samples were fixed either in formalin or Bouin's solutions. The majority of the tumours were of the clear cell RCC subtype (48 including 2 cystic RCC). Mutation screening of the 3 VHL coding exons was carried out. A descriptive analysis was performed to compare exposed and non exposed cases of clear cell RCC in terms of prevalence of mutations in both groups.

Results: In the 48 cases of RCC, four VHL mutations were detected: within exon 1 (c.332G>A, p.Ser111Asn), at the exon 2 splice site (c.463+1G>C and c.463+2T>C) and within exon 3 (c.506T>C, p.Leu169Pro).No difference was observed regarding the frequency of mutations in exposed versus unexposed groups: among the clear cell RCC, 25 had been exposed to TCE and 23 had no history of occupational exposure to TCE. Two patients with a mutation were identified in each group.

Conclusion: This study does not confirm the association between the number and type of VHL gene mutations and exposure to TCE previously described.
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http://dx.doi.org/10.1186/1745-6673-2-13DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2211482PMC
November 2007

[Genetics and angiogenesis: the example of von Hippel-Lindau disease].

Bull Cancer 2007 Jul;94 Spec No:S170-9

Laboratoire de génétique oncologique Ephe, CNRS FRE 2939, Faculté de Médecine Paris-Sud, 94276 Le Kremlin-Bicêtre et Institut de cancérologie Gustave Roussy, 94800 Villejuif.

Von Hippel-Lindau (VHL) disease is the main cause of inherited kidney cancer and the model of tumoral angiogenesis. This rare syndrome is caused by germline mutations of the VHL tumor-suppressor gene that predispose to the development of a panel of highly vascularized tumors. Main manifestations include CNS and retinal haemangioblastomas, endolymphatic sac tumors, clear-cell renal cell carcinomas (RCC), phaeochromocytomas and pancreatic neuroendocrine tumors. The VHL gene plays a major role in regulation of the oxygen-sensing pathway by targeting the hypoxia-inducible factor HIF for degradation in proteasome. Somatic inactivation of the VHL gene occurs also in most sporadic RCC. Recent progress are pawing the way for the development of antiangiogenic targeted therapies that have already shown promising results in metastatic sporadic RCC.
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July 2007

Novel somatic mutations of the VHL gene in an erythropoietin-producing renal carcinoma associated with secondary polycythemia and elevated circulating endothelial progenitor cells.

Am J Hematol 2008 Feb;83(2):155-8

INSERM Unit 602, Villejuif, France.

Mutation of the VHL tumor suppressor gene is a frequent genetic event in the carcinogenesis of renal-cell carcinoma (RCC). Circulating endothelial progenitor cells (EPCs) have important role in neoangiogenesis, and mobilization of these cells is induced by various growth factors including erythropoietin (EPO). With this regard, we analyzed a patient with EPO-producing clear-cell RCC and polycythemia. DNA extraction and sequencing analysis of the VHL gene were performed from the tumor and the adjacent normal renal tissue. Isolated and cultured circulating EPCs from the blood taken with phlebotomy were characterized by flow cytometry and immunofluorescence analysis. This RCC had two novel somatic mutations of the VHL gene, p.Leu128Pro and p.Asn131Lys. Culture of blood mononuclear cells revealed a strikingly high number of endothelial cell colonies derived from EPCs (nearly 10-fold more than in controls). Elevated number of circulating EPCs seems to be related to high EPO production from RCC with novel double somatic mutation of the VHL gene in this patient.
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http://dx.doi.org/10.1002/ajh.21019DOI Listing
February 2008

Crypt-restricted proliferation and commitment to the Paneth cell lineage following Apc loss in the mouse intestine.

Development 2005 Mar 16;132(6):1443-51. Epub 2005 Feb 16.

Institut Cochin, INSERM U567, CNRS UMR8104, Université Paris V, 24 rue du Fb St-Jacques, 75014 Paris, France.

Loss of Apc appears to be one of the major events initiating colorectal cancer. However, the first events responsible for this initiation process are not well defined and the ways in which different epithelial cell types respond to Apc loss are unknown. We used a conditional gene-ablation approach in transgenic mice expressing tamoxifen-dependent Cre recombinase all along the crypt-villus axis to analyze the immediate effects of Apc loss in the small intestinal epithelium, both in the stem-cell compartment and in postmitotic epithelial cells. Within 4 days, Apc loss induced a dramatic enlargement of the crypt compartment associated with intense cell proliferation, apoptosis and impairment of cell migration. This result confirms the gatekeeper role of Apc in the intestinal epithelium in vivo. Although Apc deletion activated beta-catenin signaling in the villi, we observed neither proliferation nor morphological change in this compartment. This highlights the dramatic difference in the responses of immature and differentiated epithelial cells to aberrant beta-catenin signaling. These distinct biological responses were confirmed by molecular analyses, revealing that Myc and cyclin D1, two canonical beta-catenin target genes, were induced in distinct compartments. We also showed that Apc is a crucial determinant of cell fate in the murine intestinal epithelium. Apc loss perturbs differentiation along the enterocyte, goblet and enteroendocrine lineages, and promotes commitment to the Paneth cell lineage through beta-catenin/Tcf4-mediated transcriptional control of specific markers of Paneth cells, the cryptdin/defensin genes.
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http://dx.doi.org/10.1242/dev.01700DOI Listing
March 2005

Is the gene encoding Chibby implicated as a tumour suppressor in colorectal cancer ?

BMC Cancer 2004 Jul 9;4:31. Epub 2004 Jul 9.

UMR-S Inserm 490, Laboratoire de Toxicologie Moléculaire, Université René Descartes-Paris V, 75006 Paris, France.

Background: A novel member of the Wnt signalling pathway, Chibby, was recently identified. This protein inhibits Wnt/beta-catenin mediated transcriptional activation by competing with Lef-1 (the transcription factor and target of beta-catenin) to bind to beta-catenin. This suggests that Chibby could be a tumour suppressor protein. The C22orf2 gene coding Chibby is located on chromosome 22, a region recurrently lost in colorectal cancer. Activation of the Wnt pathway is a major feature of colorectal cancer and occurs through inactivation of APC or activation of beta-catenin. All of this led us to analyse the possible implication of Chibby in colorectal carcinogenesis.

Methods: First, 36 tumour and matched normal colonic mucosa DNA were genotyped with five microsatellite markers located on chromosome 22 to search for loss of heterozygosity. Then, mutation screening of the C22orf2 coding sequence and splice sites was performed in the 36 tumour DNA. Finally, expression of Chibby was analysed by quantitative RT-PCR on 10 patients, 4 with loss of heterozygosity (LOH) on chromosome 22.

Results: Loss of heterozygosity involving the C22orf2 region was detected in 11 out of 36 patients (30%). Sequencing analysis revealed a known variant, rs3747174, in exon 5: T321C leading to a silent amino acid polymorphism A107A. Allelic frequencies were 0.69 and 0.31 for T and C variants respectively. No other mutation was detected. Among the 10 patients studied, expression analysis revealed that Chibby is overexpressed in 2 tumours and underexpressed in 1. No correlations were found with 22q LOH status.

Conclusion: As no somatic mutation was detected in C22orf2 in 36 colorectal tumour DNA, our results do not support the implication of Chibby as a tumour suppressor in colorectal carcinogenesis. This was supported by the absence of underexpression of Chibby among the tumour samples with 22q LOH. The implication of other Wnt pathway members remains to be identified to explain the part of colorectal tumours without mutation in APC and beta-catenin.
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http://dx.doi.org/10.1186/1471-2407-4-31DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC471554PMC
July 2004

Matrix metalloproteinase 3 polymorphism: a predictive factor of response to neoadjuvant chemotherapy in head and neck squamous cell carcinoma.

Clin Cancer Res 2004 Apr;10(8):2594-9

Inserm 490 Laboratoire de Toxicologie Moléculaire, Université René Descartes ParisV, Paris.

Purpose: Treatment of head and neck cancer often associates different therapeutic modalities, including surgery, radiotherapy, and chemotherapy. In an attempt to optimize therapeutics, the identification of molecular markers linked to response to chemotherapy remains important. Recently, the involvement of metalloproteinases in resistance to chemotherapy was suggested through their interaction with the Fas/Fas ligand pathway. Indeed metalloproteinases enhance Fas ligand shedding modulating chemotherapy efficiency. On the basis of these findings, we tested the existence of a correlation between response to chemotherapy and four metalloproteinase polymorphisms in a prospective series of 148 head and neck cancer patients.

Experimental Design: Patients were genotyped using automated fragment analysis and 5'-nuclease allelic discrimination assay. Response to chemotherapy was clinically assessed without knowledge of the genotype status.

Results: A significant relation between the metalloproteinase type 3 (MMP3) -1612insA polymorphism and response to chemotherapy was identified. Indeed, patients with the 6A/6A genotype responded more frequently (86%) to treatment as compared with patients with the 5A/6A (65%) or 5A/5A (55%) genotypes (P = 0.04). A multivariate analysis, including tumor stage, gender, TP53 mutations, and MMP3 polymorphism, showed that the 6A/6A genotype was an independent factor of response to 5-fluorouracil-cisplatin chemotherapy in head and neck cancer patients with an odds ratio of 6.7 as compared with the 5A/5A genotype.

Conclusions: This work showed that genotyping the MMP3 gene enhancer polymorphism -1612insA could help predict chemosensitivity in head and neck cancer patients.
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http://dx.doi.org/10.1158/1078-0432.ccr-1116-03DOI Listing
April 2004

Characterisation of a 161 kb deletion extending from the NBR1 to the BRCA1 genes in a French breast-ovarian cancer family.

Hum Mutat 2003 Jun;21(6):654

Service de Génétique Oncologique, Institut Curie, Paris, France.

A large germline deletion removing exons 1 to 22 of the BRCA1 gene has been previously detected using quantitative PCR based methods (QMPSF and real time PCR gene dosage assay) in a woman affected with breast and ovarian cancer. Here, we report its characterisation by using colour bar code on combed DNA of the BRCA1 region. The 5' boundary is located in a Alu Y sequence in NBR1 intron 18 whereas the 3' boundary is located in a Alu Sc sequence in BRCA1 intron 22. This 161 kb deletion encompassing the NBR1, PsiBRCA1, NBR2 and BRCA1 genes is the largest BRCA1 deletion reported so far. No specific phenotype was associated with the hemizygosity of these four genes.
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http://dx.doi.org/10.1002/humu.9148DOI Listing
June 2003

BRCA1 wild-type allele modifies risk of ovarian cancer in carriers of BRCA1 germ-line mutations.

Cancer Epidemiol Biomarkers Prev 2003 Feb;12(2):90-5

Centre National de la Recherche Scientifique, UMR 5641, Lyon, France.

Strong inter- and intrafamilial variation of penetrance of breast and ovarian cancer is observed in BRCA1 mutation carriers. The wild-type copy of the BRCA1 gene is a plausible candidate as a cancer risk modifier given that the residual function corresponding to the intact BRCA1 allele may influence the process of tumor formation in BRCA1 carriers. Indeed, growing evidence is now becoming available on impaired reparation of double-strand DNA breaks in cells heterozygous for BRCA1 mutations, implying an enhanced mutability of BRCA1(+/-) cells. To determine whether certain variant forms of the wild-type BRCA1 allele are implicated in variation of the BRCA1-related cancer risk, their effect was studied in a panel of 591 women with BRCA1 germ-line mutations. We found that BRCA1 carriers with the wild-type BRCA1 copy bearing a common Gly1038 variant were at increased risk of ovarian cancer (hazards ratio, 1.50; 95% confidence interval, 1.03-2.19). The results of our study imply that a quite significant proportion of the interindividual variability in ovarian cancer penetrance in BRCA1 carriers may be explained by a common BRCA1 Gly1038 wild-type allele, given its high frequency (0.27).
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February 2003

Significant contribution of large BRCA1 gene rearrangements in 120 French breast and ovarian cancer families.

Oncogene 2002 Oct;21(44):6841-7

Service de Génétique Oncologique, Institut Curie, Paris, France.

Genetic linkage data have shown that alterations of the BRCA1 gene are responsible for the majority of hereditary breast-ovarian cancers. However, BRCA1 germline mutations are found much less frequently than expected, especially as standard PCR-based mutation detection approaches focus on point and small gene alterations. In order to estimate the contribution of large gene rearrangements to the BRCA1 mutation spectrum, we have extensively analysed a series of 120 French breast-ovarian cancer cases. Thirty-eight were previously found carrier of a BRCA1 point mutation, 14 of a BRCA2 point mutation and one case has previously been reported as carrier of a large BRCA1 deletion. The remaining 67 cases were studied using the BRCA1 bar code approach on combed DNA which allows a panoramic view of the BRCA1 region. Three additional rearrangements were detected: a recurrent 23.8 kb deletion of exons 8-13, a 17.2 kb duplication of exons 3-8 and a 8.6 kb duplication of exons 18-20. Thus, in our series, BRCA1 large rearrangements accounted for 3.3% (4/120) of breast-ovarian cancer cases and 9.5% (4/42) of the BRCA1 gene mutation spectrum, suggesting that their screening is an important step that should be now systematically included in genetic testing surveys.
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http://dx.doi.org/10.1038/sj.onc.1205685DOI Listing
October 2002

Rapid detection of novel BRCA1 rearrangements in high-risk breast-ovarian cancer families using multiplex PCR of short fluorescent fragments.

Hum Mutat 2002 Sep;20(3):218-26

INSERM EMI 9906, IFRMP, Faculté de Médecine et Pharmacie, Rouen, France.

Recent studies have revealed a significant proportion of BRCA1 exon deletions or duplications in breast-ovarian cancer families with high probability of BRCA1- or BRCA2-linked predisposition, in which mutations of these genes have not been found. The difficulty of detecting such heterozygous rearrangements has stimulated the development of several new screening methods. Quantitative fluorescent multiplex PCR is based on simultaneous amplification of multiple target sequences under conditions that allow rapid and reliable quantitative comparison of the fluorescence of each amplicon in test samples and in controls. The modified method described here, named quantitative multiplex PCR of short fluorescent fragments (QMPSF), is particularly well suited for large genes. All BRCA1 coding exons were analyzed using four multiplexes in 52 families without point mutations in the exons or splice-sites of BRCA1 and BRCA2, and selected because of high probability of a BRCA1- or BRCA2-linked genetic predisposition. Five distinct BRCA1 rearrangements were detected: a deletion of exons 8-13, a duplication of exons 3-8, a duplication of exons 18-20, a deletion of exons 15-16, and a deletion of exons 1-22-which is the largest deletion found so far within the BRCA1 gene. The method described here lends itself to rapid, sensitive, and cost-effective search of BRCA1 rearrangements and may be included into the routine molecular analysis of breast-ovarian cancer predispositions. Hum Mutat 20:218-226, 2002.
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http://dx.doi.org/10.1002/humu.10108DOI Listing
September 2002

Distinct BRCA1 rearrangements involving the BRCA1 pseudogene suggest the existence of a recombination hot spot.

Am J Hum Genet 2002 Apr 5;70(4):858-65. Epub 2002 Mar 5.

Laboratoire de Génétique, Unité Mixte de Recherche 5641 CNRS, Université Claude Bernard, 8 avenue Rockefeller, 69373 Lyon cedex 08, France.

The 5' end of the breast and ovarian cancer-susceptibility gene BRCA1 has previously been shown to lie within a duplicated region of chromosome band 17q21. The duplicated region contains BRCA1 exons 1A, 1B, and 2 and their surrounding introns; as a result, a BRCA1 pseudogene (PsiBRCA1) lies upstream of BRCA1. However, the sequence of this segment remained essentially unknown. We needed this information to investigate at the nucleotide level the germline deletions comprising BRCA1 exons 1A, 1B, and 2, which we had previously identified in two families with breast and ovarian cancer. We have analyzed the recently deposited nucleotide sequence of the 1.0-Mb region upstream of BRCA1. We found that 14 blocks of homology between the tandemly repeated copies (cumulative length = 11.5 kb) show similarity of 77%-92%. Gaps between blocks result from insertion or deletion, usually of repetitive elements. BRCA1 exon 1A and PsiBRCA1 exon 1A are 44.5 kb apart. In the two families with breast and ovarian cancer mentioned above, distinct homologous recombination events occurred between intron 2 of BRCA1 and intron 2 of PsiBRCA1, leading to 37-kb deletions. Breakpoint junctions were found to be located at close but distinct sites within segments that are 98% identical. The mutant alleles lack the BRCA1 promoter and harbor a chimeric gene consisting of PsiBRCA1 exons 1A, 1B, and 2, which lacks the initiation codon, fused to BRCA1 exons 3-24. Thus, we report a new mutational mechanism for the BRCA1 gene. The presence of a large region homologous to BRCA1 on the same chromosome appears to constitute a hot spot for recombination.
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http://dx.doi.org/10.1086/339434DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC379114PMC
April 2002