Marion Gauthier-Villars

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

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.

Common Breast Cancer-Predisposition Alleles Are Associated with Breast Cancer Risk in BRCA1 and BRCA2 Mutation Carriers

Germline mutations in BRCA1 and BRCA2 confer high risks of breast cancer. However, evidence suggests that these risks are modified by other genetic or environmental factors that cluster in families. A recent genome-wide association study has shown that common alleles at single nucleotide polymorphisms (SNPs) in FGFR2 (rs2981582), TNRC9 (rs3803662), and MAP3K1 (rs889312) are associated with increased breast cancer risks in the general population. To investigate whether these loci are also associated with breast cancer risk in BRCA1 and BRCA2 mutation carriers, we genotyped these SNPs in a sample of 10,358 mutation carriers from 23 studies. The minor alleles of SNP rs2981582 and rs889312 were each associated with increased breast cancer risk in BRCA2 mutation carriers (per-allele hazard ratio [HR] = 1.32, 95% CI: 1.20-1.45, p(trend) = 1.7 x 10(-8) and HR = 1.12, 95% CI: 1.02-1.24, p(trend) = 0.02) but not in BRCA1 carriers. rs3803662 was associated with increased breast cancer risk in both BRCA1 and BRCA2 mutation carriers (per-allele HR = 1.13, 95% CI: 1.06-1.20, p(trend) = 5 x 10(-5) in BRCA1 and BRCA2 combined). These loci appear to interact multiplicatively on breast cancer risk in BRCA2 mutation carriers. The differences in the effects of the FGFR2 and MAP3K1 SNPs between BRCA1 and BRCA2 carriers point to differences in the biology of BRCA1 and BRCA2 breast cancer tumors and confirm the distinct nature of breast cancer in BRCA1 mutation carriers.

Familial Invasive Breast Cancers: Worse Outcome Related to BRCA1 Mutations

PURPOSE Although all studies confirm that BRCA1 tumors are highly proliferative and poorly differentiated, their outcomes remain controversial. We propose to examine, through a cohort study, the pathologic characteristics, overall survival, local recurrence, and metastasis-free intervals of 40 patients with BRCA1 breast cancer. PATIENTS AND METHODS A cohort of 183 patients with invasive breast cancer, treated at the Institut Curie and presenting with a familial history of breast and/or ovarian cancer, were tested for BRCA1 germ-line mutation. Tumor characteristics and clinical events were extracted from our prospectively registered database. RESULTS Forty BRCA1 mutations were found among the 183 patients (22%). Median follow-up was 58 months. BRCA1 tumors were larger in size (P =.03), had a higher rate of grade 3 histoprognostic factors (P =.002), and had a higher frequency of negative estrogen (P =.003) and progesterone receptors (P =.002) compared with non-BRCA1 tumors. Overall survival was poorer for carriers than for noncarriers (5-year rate, 80% v 91%, P =.002). Because a long time interval between cancer diagnosis and genetic counseling artificially increases survival time due to unrecorded deaths, the analysis was limited to the 110 patients whose diagnosis-to-counseling interval was less than 36 months (19 BRCA1 patients and 91 non-BRCA1 patients). The differences between the BRCA1 and non-BRCA1 groups regarding overall survival and metastasis-free interval were dramatically increased (49% v 85% and 18% v 84%, respectively). Multivariate analysis showed that BRCA1 mutation was an independent prognostic factor. CONCLUSION Our results strongly support that among patients with familial breast cancer, those who have a BRCA1 mutation have a worse outcome than those who do not.

Evaluation of in silico splice tools for decision‐making in molecular diagnosis

It appears that all types of genomic nucleotide variations can be deleterious by affecting normal pre‐mRNA splicing via disruption/creation of splice site consensus sequences. As it is neither pertinent nor realistic to perform functional testing for all of these variants, it is important to identify those that could lead to a splice defect in order to restrict transcript analyses to the most appropriate cases. Web‐based tools designed to provide such predictions are available. We evaluated the performance of six of these tools (Splice Site Prediction by Neural Network [NNSplice], Splice‐Site Finder [SSF], MaxEntScan [MES], Automated Splice‐Site Analyses [ASSA], Exonic Splicing Enhancer [ESE] Finder, and Relative Enhancer and Silencer Classification by Unanimous Enrichment [RESCUE]‐ESE) using 39 unrelated retinoblastoma patients carrying different RB1 variants (31 intronic and eight exonic). These 39 patients were screened for abnormal splicing using puromycin‐treated cell lines and the results were compared to the predictions. As expected, 17 variants impacting canonical AG/GT splice sites were correctly predicted as deleterious. A total of 22 variations occurring at loosely defined positions (±60 nucleotides from an AG/GT site) led to a splice defect in 19 cases and 16 of them were classified as deleterious by at least one tool (84% sensitivity). In other words, three variants escaped in silico detection and the remaining three were correctly predicted as neutral. Overall our results suggest that a combination of complementary in silico tools is necessary to guide molecular geneticists (balance between the time and cost required by RNA analysis and the risk of missing a deleterious mutation) because the weaknesses of one in silico tool may be overcome by the results of another tool. Hum Mutat 29(7), 975–982, 2008.

Exposure to diagnostic radiation and risk of breast cancer among carriers of BRCA1/2 mutations: retrospective cohort study (GENE-RAD-RISK)

Objective To estimate the risk of breast cancer associated with diagnostic radiation in carriers of BRCA1/2 mutations. Design Retrospective cohort study (GENE-RAD-RISK). Setting Three nationwide studies (GENEPSO, EMBRACE, HEBON) in France, United Kingdom, and the Netherlands, Participants 1993 female carriers of BRCA1/2 mutations recruited in 2006-09. Main outcome measure Risk of breast cancer estimated with a weighted Cox proportional hazards model with a time dependent individually estimated cumulative breast dose, based on nominal estimates of organ dose and frequency of self reported diagnostic procedures. To correct for potential survival bias, the analysis excluded carriers who were diagnosed more than five years before completion of the study questionnaire. Results In carriers of BRCA1/2 mutations any exposure to diagnostic radiation before the age of 30 was associated with an increased risk of breast cancer (hazard ratio 1.90, 95% confidence interval 1.20 to 3.00), with a dose-response pattern. The risks by quarter of estimated cumulative dose <0.0020 Gy, ≥0.0020-0.0065 Gy, ≥0.0066-0.0173 Gy, and ≥0.0174 Gy were 1.63 (0.96 to 2.77), 1.78 (0.88 to 3.58), 1.75 (0.72 to 4.25), and 3.84 (1.67 to 8.79), respectively. Analyses on the different types of diagnostic procedures showed a pattern of increasing risk with increasing number of radiographs before age 20 and before age 30 compared with no exposure. A history of mammography before age 30 was also associated with an increased risk of breast cancer (hazard ratio 1.43, 0.85 to 2.40). Sensitivity analysis showed that this finding was not caused by confounding by indication of family history. Conclusion In this large European study among carriers of BRCA1/2 mutations, exposure to diagnostic radiation before age 30 was associated with an increased risk of breast cancer at dose levels considerably lower than those at which increases have been found in other cohorts exposed to radiation. The results of this study support the use of non-ionising radiation imaging techniques (such as magnetic resonance imaging) as the main tool for surveillance in young women with BRCA1/2 mutations.

Revisiting Li-Fraumeni Syndrome From TP53 Mutation Carriers

PURPOSE The aim of the study was to update the description of Li-Fraumeni syndrome (LFS), a remarkable cancer predisposition characterized by extensive clinical heterogeneity. PATIENTS AND METHODS From 1,730 French patients suggestive of LFS, we identified 415 mutation carriers in 214 families harboring 133 distinct TP53 alterations and updated their clinical presentation. RESULTS The 322 affected carriers developed 552 tumors, and 43% had developed multiple malignancies. The mean age of first tumor onset was 24.9 years, 41% having developed a tumor by age 18. In childhood, the LFS tumor spectrum was characterized by osteosarcomas, adrenocortical carcinomas (ACC), CNS tumors, and soft tissue sarcomas (STS) observed in 30%, 27%, 26%, and 23% of the patients, respectively. In adults, the tumor distribution was characterized by the predominance of breast carcinomas observed in 79% of the females, and STS observed in 27% of the patients. The TP53 mutation detection rate in children presenting with ACC or choroid plexus carcinomas, and in females with breast cancer before age 31 years, without additional features indicative of LFS, was 45%, 42% and 6%, respectively. The mean age of tumor onset was statistically different (P < .05) between carriers harboring dominant-negative missense mutations (21.3 years) and those with all types of loss of function mutations (28.5 years) or genomic rearrangements (35.8 years). Affected children, except those with ACC, harbored mostly dominant-negative missense mutations. CONCLUSION The clinical gradient of the germline TP53 mutations, which should be validated by other studies, suggests that it might be appropriate to stratify the clinical management of LFS according to the class of the mutation.

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

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.

Bar code screening on combed DNA for large rearrangements of the BRCA1 and BRCA2 genes in French breast cancer families

Identification of the BRCA1 and BRCA2 genes was a major advance in the understanding of the familial forms of breast cancer, as alterations of these genes result in a high predisposition to breast cancer.1,2 To date, analysis of BRCA1 and BRCA2 coding sequences by mutation screening methods based on PCR sequencing protocols has allowed the identification of at least 900 different point or small disease causing germline alterations (Breast Cancer Information Core, BIC database). Furthermore, several large BRCA1 rearrangements have been reported, detected by Southern blotting, lymphocyte transcript analysis, or long range PCR.3–14 The majority of characterised rearrangements result from unequal recombination events between Alu sequences. We have estimated that the contribution of large rearrangements to the spectrum of BRCA1 mutations is close to 10% in French breast-ovarian cancer families.15 Only two rearrangements of the BRCA2 gene have been detected to date: a 5 kb deletion skipping exon 3 and a 6.2 kb deletion removing exons 12-13.16,17 However, few groups have systematically looked for BRCA2 rearrangements in defined series of breast cancer cases.17–19 In order to detect such rearrangements, we have developed a bar code on combed DNA for the BRCA2 gene, which leads to a panoramic view of this gene and its flanking regions, as previously described for BRCA1. 20,21 We have concurrently used BRCA1 and BRCA2 bar codes to analyse a series of 26 highly selected French patients with a family history of breast cancer only, who were previously found to be negative for point or small mutations in both BRCA1 and BRCA2 genes. From January 1991 to December 1999, women with breast cancer (index cases), ascertained in the Institut Curie cancer genetic clinic were referred to our laboratory for BRCA1 / 2 analysis. Familial criteria for genetic …

A deep intronic mutation in the RB1 gene leads to intronic sequence exonisation.

Familial forms of retinoblastoma, an embryonic neoplasm of retinal origin, are caused by constitutional mutations of the RB1 gene. In this paper, we describe a family with retinoblastoma affecting two brothers with no previous family history of cancer. Complete RB1 mutational screening including point mutation and large rearrangement screening failed to demonstrate any mutation. The whole coding sequence was therefore investigated at the cDNA level, demonstrating a 103 bp intronic insertion between exons 23 and 24, leading to subsequent frameshift and premature termination of translation. This intronic exonisation was caused by a deep intronic mutation in intron 23 generating a cryptic 3′ splice site. This is the first report of a deep intronic mutation in RB1 and is a proof of concept that some undetected RB1 mutations should be investigated at the cDNA level, particularly in hereditary forms of retinoblastoma.

Results of a Multicenter Prospective Study on the Postoperative Treatment of Unilateral Retinoblastoma After Primary Enucleation

PURPOSE The objective of this prospective study was to assess overall survival and event-free survival in patients with intraocular unilateral retinoblastoma (Reese-Ellsworth group V) treated by primary enucleation with or without adjuvant therapy depending on histopathologic risk factors. PATIENTS AND METHODS Patients (n = 123) were divided into three groups on the basis of risk factors for extraocular relapse and metastasis assessed on centralized histologic examination of enucleated eyes. Group 1 (n = 70) had minimal or no choroidal involvement and/or prelaminar or no optic nerve involvement and received no adjuvant therapy. Group 2 (n = 52) had massive choroidal involvement and/or intra- or retrolaminar optic nerve involvement and/or anterior segment involvement and received four courses of adjuvant chemotherapy. Group 3 (n = 1) had invasion of the surgical margin of the optic nerve and/or microscopic extrascleral involvement and received six courses of adjuvant chemotherapy with intrathecal thiotepa, consolidation chemotherapy, and autologous stem-cell rescue. Genetic testing was also performed. RESULTS Median follow-up for the 123 patients was 71 months. No disease progression, relapse, or distant metastasis occurred during follow-up. No second malignancies occurred. This requires confirmation with longer follow-up. Secondary bilateralization occurred in two patients with identified RB1 germline mutation. Adjuvant chemotherapy was well tolerated, with limited toxicity. Molecular testing found constitutional RB1 gene mutations in only nine of 100 evaluated patients. CONCLUSION The survival rate of 100% was excellent, including 57% of patients who received no adjuvant therapy, suggesting that chemotherapy could be de-escalated in some patients, especially those with massive choroidal involvement.