Sircoulomb F.,French Institute of Health and Medical Research |
Bekhouche I.,French Institute of Health and Medical Research |
Finetti P.,French Institute of Health and Medical Research |
Adelaide J.,French Institute of Health and Medical Research |
And 18 more authors.
BMC Cancer | Year: 2010
Background: Around 20% of breast cancers (BC) show ERBB2 gene amplification and overexpression of the ERBB2 tyrosine kinase receptor. They are associated with a poor prognosis but can benefit from targeted therapy. A better knowledge of these BCs, genomically and biologically heterogeneous, may help understand their behavior and design new therapeutic strategies.Methods: We defined the high resolution genome and gene expression profiles of 54 ERBB2-amplified BCs using 244K oligonucleotide array-comparative genomic hybridization and whole-genome DNA microarrays. Expression of ERBB2, phosphorylated ERBB2, EGFR, IGF1R and FOXA1 proteins was assessed by immunohistochemistry to evaluate the functional ERBB2 status and identify co-expressions.Results: First, we identified the ERBB2-C17orf37-GRB7 genomic segment as the minimal common 17q12-q21 amplicon, and CRKRS and IKZF3 as the most frequent centromeric and telomeric amplicon borders, respectively. Second, GISTIC analysis identified 17 other genome regions affected by copy number aberration (CNA) (amplifications, gains, losses). The expression of 37 genes of these regions was deregulated. Third, two types of heterogeneity were observed in ERBB2-amplified BCs. The genomic profiles of estrogen receptor-postive (ER+) and negative (ER-) ERBB2-amplified BCs were different. The WNT/β-catenin signaling pathway was involved in ER- ERBB2-amplified BCs, and PVT1 and TRPS1 were candidate oncogenes associated with ER+ ERBB2-amplified BCs. The size of the ERBB2 amplicon was different in inflammatory (IBC) and non-inflammatory BCs. ERBB2-amplified IBCs were characterized by the downregulated and upregulated mRNA expression of ten and two genes in proportion to CNA, respectively. IHC results showed (i) a linear relationship between ERBB2 gene amplification and its gene and protein expressions with a good correlation between ERBB2 expression and phosphorylation status; (ii) a potential signaling cross-talk between EGFR or IGF1R and ERBB2, which could influence response of ERBB2-positive BCs to inhibitors. FOXA1 was frequently coexpressed with ERBB2 but its expression did not impact on the outcome of patients with ERBB2-amplified tumors.Conclusion: We have shown that ER+ and ER- ERBB2-amplified BCs are different, distinguished ERBB2 amplicons in IBC and non-IBC, and identified genomic features that may be useful in the design of alternative therapeutical strategies. © 2010 Sircoulomb et al; licensee BioMed Central Ltd.
Messaoud O.,Pasteur Institute of Tunis |
Ben Rekaya M.,Pasteur Institute of Tunis |
Cherif W.,Pasteur Institute of Tunis |
Talmoudi F.,Pasteur Institute of Tunis |
And 6 more authors.
International Journal of Dermatology | Year: 2010
Background: Xeroderma Pigmentosum (XP) is a rare autosomal recessive disorder characterized by cutaneous and ocular alterations. Eight genes, Xeroderma Pigmentosum group A (XPA) to Xeroderma Pigmentosum group G (XPG) and Xeroderma Pigmentosum group V (XPV), are known to be responsible for the disease and products of these genes are involved in the repair of deoxyribonucleic acid (DNA) lesions generated by UV radiation. Several XP patients suffer from neurological defects, found in the XPA (the most common form), D and G groups. The aim of this study was to investigate the mutational spectrum of XPA in Tunisia, in order to propose a simple tool for molecular diagnosis. Methods: This study was carried out on six unrelated families with nine Tunisian XPA patients. Clinical features were recorded. As a previous study showed the presence of the R228X mutation in Tunisia, patients were first screened for this mutation by polymerase chain reaction-restriction fragment length polymorphism and then confirmed by direct sequencing. Results: The results showed that all patients carried the XPA R228X mutation. This mutation corresponds to a C to T transition, which creates a premature stop codon at position 228, thus causing a DNA repair defect. Conclusions: The XPA R228X mutation is common in Tunisian population. This mutation is associated with a relatively moderate phenotype of the XPA. As all explored patients presented the recurrent mutation XPA R228X, a potential founder effect was searched and confirmed by haplotype analysis. Taking into account similar genetic background, investigation of this mutation should allow a cost effective and rapid diagnosis of XPA in north-African populations. © 2010 The International Society of Dermatology.
Riahi A.,Tunis el Manar University |
Messaoudi A.,Higher Institute of Biotechnology of Beja |
Mrad R.,Charles Nicolle Hospital |
Fourati A.,Salah Azaiz Institute |
And 2 more authors.
Journal of Theoretical Biology | Year: 2016
The significance of many BRCA unclassified variants (UVs) has not been evaluated. Classification of these variations as neutral or pathogenic presents a significant challenge and has important implications for breast and ovarian cancer genetic counseling. Here we report a combined molecular and computational approach to classify BRCA UVs missense variations. By using the LOH (Loss of heterozygosity) analysis at the BRCA1/BRCA2 loci, five bioinformatics approaches namely fathmm, PhD-SNP, SNAP, MutationTaster and Human Splicing Finder and the association with the clinico-pathological characteristics related to BRCA tumors, we were able to classify the R2787H (in BRCA2 gene) variant as pathogenic. Then, to investigate the functional role of the R2787H variation in altering BRCA2 structure, the homology model of this variant was constructed using the Rattus norvegicus BRCA2 (PDB ID: 1IYJ) as a template. The predicted model was then assessed for stereochemical quality and side chain environment. Furthermore, docking and binding free energy simulations were performed to investigate the ssDNA-BRCA2 complex interaction. Binding energy value calculation proves that this substitution affects the complex stability. Moreover, this alteration was not found in one hundred healthy controls. These findings suggest that R2787H variant could have potential functional impact. Our approach might be useful for evaluation of BRCA unclassified variants. However additional functional analyzes may provide appropriate assessment to classify such variants. © 2016 Elsevier Ltd.
Riahi A.,Tunis el Manar University |
Ghourabi M.E.,University of Tunis |
Fourati A.,Salah Azaiz Institute |
Chaabouni-Bouhamed H.,Charles Nicolle Hospital
Breast Cancer | Year: 2016
Background: With the increasing request for BRCA1/BRCA2 mutation tests, several risk models have been developed to predict the presence of mutation in these genes; in this study, we have developed an efficient BRCA genetic testing strategy. Method: As first step, to identify predictor variables associated with BRCA status, we have undertaken a cumulative mutation analysis including data from three Tunisian studies. Then, we have developed a logistic regression model for predicting the likelihood of harboring a BRCA mutation. Using receiver operating characteristic curves (ROC), an effective evaluation was performed. A total of 92 Tunisian families were included. Overall, 27 women were positive for BRCA1/BRCA2 deleterious mutations. Results: Tow recurrent mutations (c.211dupA and c.5266dupC) explained 76 % of BRCA1-related families and three recurrent mutations (c.1310_1313del, c.1542_1547delAAGA and c.7887_7888insA) explained 90 % of BRCA2-related families. Early age at diagnosis of breast cancer, ovarian cancer, bilateral breast cancer were associated with BRCA1, whereas male breast cancer and four or more breast cancer cases in the family were associated with BRCA2. The area under the receiver operating characteristic curve of the risk score was 0.802 (95 % confidence interval = 0.0699–0. 905). Conclusion: Logistic regression reported particular profiles related to BRCA germline mutation carriers in our population, as well as an efficient prediction model that may be a useful tool for increasing the cost-effectiveness of genetic testing strategy. © 2016 The Japanese Breast Cancer Society
Boussen H.,Institute Salah Azaiz |
Bouzaiene H.,Salah Azaiz Institute |
Hassouna J.B.,Salah Azaiz Institute |
Dhiab T.,Salah Azaiz Institute |
And 7 more authors.
Cancer | Year: 2010
Inflammatory breast cancer (IBC) is characterized by a peculiar geographic distribution in incidence, being described as more common in Tunisia and the region of North Africa. The authors performed a systematic review of published literature on rapidly progressing breast cancer and IBC in Tunisia and analyzed the evolution in epidemiology, clinical presentation, treatment, and therapeutic results. They collected, analyzed, and compared all the indexed Tunisian articles about rapidly progressing breast cancer and IBC since the 1970s opening of the Institut Salah Azaiz Institute in Tunis. In the 1970s, rapidly progressing breast cancer diagnosis was based on the Poussée Évolutive classification (1-3). Since the 1990s, IBC diagnosis has been based on the American Joint Committee on Cancer Poussée Évolutive 3/T4d staging. The authors compared the historical data to the most recent publications in terms of epidemiology, clinical features, treatment, and therapeutic results. The most important historical report of rapidly progressing breast cancer concerned 340 patients, representing 58.5% of a cohort of 581 breast cancer patients collected from 1969 to 1974, including 320 (55.2%) with inflammatory signs, 37(6.5%) with Poussée Évolutive 2, and 283 (48.7%) with Poussée Évolutive 3. Subsequent papers have documented a steady decrease in incidence to the current 5% to 7% T4d/IBC. Since the 1970s, Poussée Évolutive in premenopausal woman has increased from 52.5% to 75%; rural predominance has persisted. The 5-year overall survival reached 28% by the year 2000. The authors' analysis demonstrated a trend of decreasing incidence of IBC diagnoses from 50% to presently <10%, probably related to a combination of factors, including the use of more stringent criteria (Poussée Évolutive 3/T4d) for IBC diagnosis and an improvement in the socioeconomic level of Tunisia. © 2010 American Cancer Society.