Identificação e caracterização molecular de mutações germinativas em indivíduos com síndrome de câncer de mama e ovário hereditário

Hereditary breast and ovarian cancer (HBOC) corresponds to 10-15% of all diagnosed cases of breast cancer in the world. The majority germline mutations are identified in BRCA1 and BRCA2 genes, however the application of multigene panels has increased the number of pathogenic variations detected in DNA repair genes. According to the current version of NCCN (National Comprehensive Cancer Network) Guideline, mutations in BRCA1, BRCA2, TP53 and PTEN confers high risk to develop breast cancer, and mutations in CDH1, CHEK2, PALB2, ATM and BRIP can increases over than 20% this risk. We analyzed 157 individuals with personal and/or familial breast cancer history. Genomic DNA was isolated from peripheral blood through saline-based extraction and samples were analyzed using next-generation sequencing (NGS). We identified 15 pathogenic variants and 4 VUS (Variants of Uncertain Significance) in 27 individuals (27/157; 17%), in which three are asymptomatic. Seven novel variants in 4 genes were identified: BRCA1_c.3409A>G; BRCA2_g.26826_30318del, BRCA2_c.5800C>T; BRCA2_c.5228G>A; BRCA2_c.5305delG; ATM_c.634delT and ATR_c.3043C>T. Sixty-eight percent (13/19; 68%) of variants was detected in BRCA1 and BRCA2 genes, while 32% (6/19) were identified in moderate risk genes ATM (2/19); ATR (1/19); CDH1 (1/19); MLH1 (1/19) and MSH6 (1/19). The individuals were separated in two groups for comparative analysis: high-risk genes and moderate risk genes. Among three asymptomatic individuals, two present variants in moderate risk genes ATM and MLH1. Among breast cancer individuals, eighteen patients (18/24; 75%) presented mutations in high-risk genes, while six (6/24; 25%) harbored mutations in moderate risk genes. Both groups had a high incidence of early-onset breast cancer, 83%. The group of individuals harboring variants in high-risk genes presented a greater occurrence of high-grade tumors (83% vs. 67%, P= 0.0090). In the group of individuals harboring mutation in moderate risk genes, tumors presented a more aggressive phenotype with bilateral cancer (33% vs. 11%, P= 0.0002), occurrence of metastasis (33% vs. 5.6%, PG; BRCA2_g.26826_30318del, BRCA2_c.5800C>T; BRCA2_c.5228G>A; BRCA2_c.5305delG; ATM_c.634delT e ATR_c.3043C>T. Sessenta e oito por cento (13/19; 68%) de variantes foi detectada nos genes BRCA1 e BRCA2, enquanto 32% (6/19) foram identificados nos genes de risco moderado ATM (2/19); ATR (1/19); CDH1 (1/19); MLH1 (1/19) e MSH6 (1/19). Os indivíduos foram separados em dois grupos para a análise comparativa: portadores de mutação nos genes de alto risco e nos genes de risco moderado. Entre os três indivíduos assintomáticos, duas variantes estão presentes nos genes de risco moderado ATM e MLH1. Entre os indivíduos com câncer de mama, dezoito pacientes (18/24; 75%) apresentaram mutações em genes de alto risco, enquanto seis (6/24; 25%) são portadores de mutações em genes de risco moderado. Ambos os grupos apresentaram alta incidência de câncer de mama precocemente (83% dos indivíduos). O grupo de portadores de mutação nos genes de alto risco apresentaram maior ocorrência de tumores de alto grau (83% vs 67%, P = 0,0090). No grupo de indivíduos com mutações em genes de risco moderado, os tumores apresentaram um fenótipo mais agressivo com câncer bilateral (33% versus 11%, P = 0,0002), ocorrência de metástases (33% vs 5,6%, P <0,0001) e óbito (33% vs 5,6%, P <0,0001). Ao todo, 1/3 de variantes foram identificadas em genes de risco moderado em pacientes com câncer mais agressivo. Estes resultados reforçam a importância da aplicação de análise multigênica em indivíduos em situação de risco para câncer de mama, especialmente em uma população heterogênea como brasileira

Leads from Physical, Chemical, and Thermal Characterization on Cytotoxic Effects of Xylan-Based Microparticles

Interfacial cross-linking (ICL) has been considered a feasible technique to produce polysaccharide-based microparticles (PbMs), even though only a few studies have been concerned with their biocompatibility. In this work, PbMs were prepared by the ICL method and characterized in regard to their in vitro biocompatibility, chemical linkages, and physical and thermal properties. First, the cell viability assay revealed that PbMs toxicity was concentration-dependent. Then, it was observed that the toxicity may be related to the way in which the binding occurred, and not exclusively to the stoichiometry between the polymer and the cross-linking agent. Moreover, the PbMs biosafety was predicted by the use of physicochemical procedures, which were able to identify unbound cross-linking agent residues and also to reveal the improvement of their thermal stability. Accordingly, this work suggests a step-by-step physicochemical procedure able to predict potential toxicity from micro-structured devices produced by polysaccharides. Likewise, the use of PbMs as a drug carrier should be cautiously considered