RESUMO
We report that ~1.8% of all mesothelioma patients and 4.9% of those younger than 55, carry rare germline variants of the BRCA1 associated RING domain 1 (BARD1) gene that were predicted to be damaging by computational analyses. We conducted functional assays, essential for accurate interpretation of missense variants, in primary fibroblasts that we established in tissue culture from a patient carrying the heterozygous BARD1V523A mutation. We found that these cells had genomic instability, reduced DNA repair, and impaired apoptosis. Investigating the underlying signaling pathways, we found that BARD1 forms a trimeric protein complex with p53 and SERCA2 that regulates calcium signaling and apoptosis. We validated these findings in BARD1-silenced primary human mesothelial cells exposed to asbestos. Our study elucidated mechanisms of BARD1 activity and revealed that heterozygous germline BARD1 mutations favor the development of mesothelioma and increase the susceptibility to asbestos carcinogenesis. These mesotheliomas are significantly less aggressive compared to mesotheliomas in asbestos workers.
Assuntos
Sinalização do Cálcio , Reparo do DNA , Predisposição Genética para Doença , Mutação em Linhagem Germinativa , Mesotelioma , Proteínas Supressoras de Tumor , Ubiquitina-Proteína Ligases , Humanos , Reparo do DNA/genética , Proteínas Supressoras de Tumor/genética , Proteínas Supressoras de Tumor/metabolismo , Ubiquitina-Proteína Ligases/genética , Ubiquitina-Proteína Ligases/metabolismo , Mesotelioma/genética , Sinalização do Cálcio/genética , Feminino , Masculino , Pessoa de Meia-Idade , Proteína Supressora de Tumor p53/genética , Proteína Supressora de Tumor p53/metabolismo , Apoptose/genética , Fibroblastos/metabolismo , Amianto/toxicidade , Instabilidade GenômicaRESUMO
Precise quantification of copy-number alterations (CNAs) in a tumor genome is difficult. We have applied a comprehensive copy-number analysis method, digital multiplex ligation-dependent probe amplification (digitalMLPA), for targeted gene copy-number analysis in clear cell renal cell carcinoma (ccRCC). Copy-number status of all chromosomal arms and 11 genes was determined in 60 ccRCC samples. Chromosome 3p loss and 5q gain, known as early changes in ccRCC development, as well as losses at 9p and 14q were detected in 56/60 (93.3%), 31/60 (51.7%), 11/60 (18.3%), and 33/60 (55%), respectively. Through gene expression analysis, a significant positive correlation was detected in terms of 14q loss determined using digitalMLPA and downregulation of mRNA expression ratios with HIF1A and L2HGDH (P = .0253 and .0117, respectively). Patients with early metastasis (<1 y) (n = 18) showed CNAs in 6 arms (in median), whereas metastasis-free patients (n = 34) showed those in significantly less arms (3 arms in median) (P = .0289). In particular, biallelic deletion of CDKN2A/2B was associated with multiple CNAs (≥7 arms) in 3 tumors. Together with sequence-level mutations in genes VHL, PBRM1, SETD2, and BAP1, we performed multiple correspondence analysis, which identified the association of 9p loss and 4q loss with early metastasis (both P < .05). This analysis indicated the association of 4p loss and 1p loss with poor survival (both, P < .05). These findings suggest that CNAs have essential roles in aggressiveness of ccRCC. We showed that our approach of measuring CNA through digitalMLPA will facilitate the selection of patients who may develop metastasis.
Assuntos
Carcinoma de Células Renais/genética , Cromossomos Humanos Par 14/genética , Cromossomos Humanos Par 1/genética , Cromossomos Humanos Par 9/genética , Variações do Número de Cópias de DNA , Neoplasias Renais/genética , Adulto , Idoso , Idoso de 80 Anos ou mais , Carcinoma de Células Renais/mortalidade , Estudos de Casos e Controles , Deleção Cromossômica , Regulação para Baixo , Feminino , Regulação Neoplásica da Expressão Gênica , Humanos , Neoplasias Renais/mortalidade , Masculino , Pessoa de Meia-Idade , Reação em Cadeia da Polimerase Multiplex , Metástase Neoplásica , Análise de SobrevidaRESUMO
Nutritional restriction leads to protein translation attenuation that results in the storage and degradation of free mRNAs in cytoplasmic assemblies. In this study, we show in Drosophila S2 cells that amino-acid starvation also leads to the inhibition of another major anabolic pathway, the protein transport through the secretory pathway, and to the formation of a novel reversible non-membrane bound stress assembly, the Sec body that incorporates components of the ER exit sites. Sec body formation does not depend on membrane traffic in the early secretory pathway, yet requires both Sec23 and Sec24AB. Sec bodies have liquid droplet-like properties, and they act as a protective reservoir for ERES components to rebuild a functional secretory pathway after re-addition of amino-acids acting as a part of a survival mechanism. Taken together, we propose that the formation of these structures is a novel stress response mechanism to provide cell viability during and after nutrient stress.