Breast cancer in West Africa: molecular analysis of BRCA genes in early-onset breast cancer patients in Burkina Faso.

BACKGROUND: Breast cancer (BC) is the most commonly diagnosed cancer and the second leading cause of cancer-related deaths among women in Africa after cervical cancer. Even if the epidemiological data are now aligned with those relating to industrialized countries, the knowledge concerning breast cancer in Africa, particularly in Western Africa, still lack clinical data, medical treatments, and the evaluation of genetic and non-genetic factors implicated in the etiology of the disease. The early onset and the aggressiveness of diagnosed breast cancers in patients of African ancestry strongly suggest that the genetic risk factor may be a key component, but so far, very few studies on the impact of germ line mutations in breast cancer in Africa have been conducted, with negative consequences on prevention, awareness and patient management. Through Next Generation sequencing (NGS), we analyzed all of the coding regions and the exon-intron junctions of BRCA1 and BRCA2 genes-the two most important genes in hereditary breast cancer-in fifty-one women from Burkina Faso with early onset of breast cancer with or without a family history. RESULTS: We identified six different pathogenic mutations (three in BRCA1, three in BRCA2), two of which were recurrent in eight unrelated women. Furthermore, we identified, in four other patients, two variants of uncertain clinical significance (VUS) and two variants never previously described in literature, although one of them is present in the dbSNP database. CONCLUSIONS: This is the first study in which the entire coding sequence of BRCA genes has been analyzed through Next Generation Sequencing in Burkinabe young women with breast cancer. Our data support the importance of genetic risk factors in the etiology of breast cancer in this population and suggest the necessity to improve the genetic cancer risk assessment. Furthermore, the identification of the most frequent mutations of BRCA1 and BRCA2 in the population of Burkina Faso will allow the development of an inexpensive genetic test for the identification of subjects at high genetic cancer risk, which could be used to design personalized therapeutic protocols.

Screening of EDA1 gene in X-linked anhidrotic ectodermal dysplasia using DHPLC: identification of 14 novel mutations in Italian patients.

Mutations within EDA1 gene, which encodes for the ectodysplasin, cause X-linked anhidrotic ectodermal dysplasia. In this study, 23 Italian patients with anhidrotic ectodermal dysplasia were analyzed for mutations in EDA1 gene. We set up a rapid protocol through denaturing high-performance liquid chromatography, followed by sequencing, that allowed the characterization of 18 mutations, 14 novel and 4 recurrent: 8 missense mutations (p.L51Q, p.H54R, p.R156H twice, p.C332F, p.D316H, p.T378M, and p.A349T), 3 in-frame deletions (p.G82_P84del, p.A179_P191del, and p.L354del), 1 gross deletion (p.G168_G265del, identified through direct sequencing and PCR), 4 altered splicing (c.949-13T > C, c.741 + 1G/T, c.793 + 4A > T, and c.924 + 1G/T), 1 nonsense (p.Y3X), and 1 synonymous mutation (c.741G > A). Moreover, structural analysis of three missense mutations shows that alteration of the electrostatic surface of the protein (p.D316N), the break of intermonomer interactions (p.A349T) and destabilization of the single monomer structure (p.T378M), may irreversibly invalidate the EDA-A1 binding properties. Our data confirm and extend the large spectrum of EDA1 mutations and provide a rapid and efficient molecular protocol for testing EDA1 mutations in EDA patients.

The tyrosine phosphatase Shp2 interacts with NPM-ALK and regulates anaplastic lymphoma cell growth and migration.

Anaplastic large cell lymphomas (ALCL) are mainly characterized by the reciprocal translocation t(2;5)(p23;q35) that involves the anaplastic lymphoma kinase (ALK) gene and generates the fusion protein NPM-ALK with intrinsic tyrosine kinase activity. NPM-ALK triggers several signaling cascades, leading to increased cell growth, resistance to apoptosis, and changes in morphology and migration of transformed cells. To search for new NPM-ALK interacting molecules, we developed a mass spectrometry-based proteomic approach in HEK293 cells expressing an inducible NPM-ALK and identified the tyrosine phosphatase Shp2 as a candidate substrate. We found that NPM-ALK was able to bind Shp2 in coprecipitation experiments and to induce its phosphorylation in the tyrosine residues Y542 and Y580 both in HEK293 cells and ALCL cell lines. In primary lymphomas, antibodies against the phosphorylated tyrosine Y542 of Shp2 mainly stained ALK-positive cells. In ALCL cell lines, Shp2-constitutive phosphorylation was dependent on NPM-ALK, as it significantly decreased after short hairpin RNA (shRNA)-mediated NPM-ALK knock down. In addition, only the constitutively active NPM-ALK, but not the kinase dead NPM-ALK(K210R), formed a complex with Shp2, Gab2, and growth factor receptor binding protein 2 (Grb2), where Grb2 bound to the phosphorylated Shp2 through its SH2 domain. Shp2 knock down by specific shRNA decreased the phosphorylation of extracellular signal-regulated kinase 1/2 and of the tyrosine residue Y416 in the activation loop of Src, resulting in impaired ALCL cell proliferation and growth disadvantage. Finally, migration of ALCL cells was reduced by Shp2 shRNA. These findings show a direct involvement of Shp2 in NPM-ALK lymphomagenesis, highlighting its critical role in lymphoma cell proliferation and migration.

Familial medullary thyroid carcinoma: clinical variability and low aggressiveness associated with RET mutation at codon 804.

Sixty-one heterozygotes harboring the germline V804L mutation of the RET protooncogene were identified in five independent families. A total of 31 subjects underwent surgery. Histology identified C cell hyperplasia in 30 cases, isolated in 12 and associated with medullary thyroid carcinoma (MTC) in 18. Six patients with MTC had lymph node metastases. Among the 14 patients with basal detectable calcitonin (CT) level, 12 had MTC and 2 had isolated C cell hyperplasia. In most individuals carrying 804 RET mutation, C cell disease displayed late onset and an indolent course; a pentagastrin test was negative in the majority of heterozygotes during the first 2 decades and was positive in only half of them during the third and fourth decades of life. Interestingly, concomitant somatic M918T was detected in a 12-yr-old girl with MTC and was likely to be responsible for both the early clinical appearance and the aggressiveness of the disease. Our data show that in these gene carriers, surgery may be postponed to the fourth decade of life or until the pentagastrin stimulation test becomes positive. Indeed, our data should be confirmed on a larger series of V804L carriers, but may offer a balanced strategy to keep under control and prevent development of the full disease phenotype.