RESUMEN
Considering that mutations in known prostate cancer (PrCa) predisposition genes, including those responsible for hereditary breast/ovarian cancer and Lynch syndromes, explain less than 5% of early-onset/familial PrCa, we have sequenced 94 genes associated with cancer predisposition using next generation sequencing (NGS) in a series of 121 PrCa patients. We found monoallelic truncating/functionally deleterious mutations in seven genes, including ATM and CHEK2, which have previously been associated with PrCa predisposition, and five new candidate PrCa associated genes involved in cancer predisposing recessive disorders, namely RAD51C, FANCD2, FANCI, CEP57 and RECQL4. Furthermore, using in silico pathogenicity prediction of missense variants among 18 genes associated with breast/ovarian cancer and/or Lynch syndrome, followed by KASP genotyping in 710 healthy controls, we identified "likely pathogenic" missense variants in ATM, BRIP1, CHEK2 and TP53. In conclusion, this study has identified putative PrCa predisposing germline mutations in 14.9% of early-onset/familial PrCa patients. Further data will be necessary to confirm the genetic heterogeneity of inherited PrCa predisposition hinted in this study.
Asunto(s)
Mutación de Línea Germinal , Neoplasias de la Próstata/genética , Adulto , Edad de Inicio , Proteínas de la Ataxia Telangiectasia Mutada/genética , Neoplasias de la Mama/genética , Estudios de Casos y Controles , Quinasa de Punto de Control 2/genética , Neoplasias Colorrectales Hereditarias sin Poliposis/genética , Simulación por Computador , Proteínas de Unión al ADN/genética , Proteína del Grupo de Complementación D2 de la Anemia de Fanconi/genética , Proteínas del Grupo de Complementación de la Anemia de Fanconi/genética , Femenino , Genes p53 , Predisposición Genética a la Enfermedad , Variación Genética , Secuenciación de Nucleótidos de Alto Rendimiento , Humanos , Masculino , Proteínas Asociadas a Microtúbulos/genética , Persona de Mediana Edad , Mutación Missense , Proteínas Nucleares/genética , Neoplasias Ováricas/genética , Linaje , ARN Helicasas/genética , RecQ Helicasas/genética , Análisis de Secuencia de ADNRESUMEN
Since the first studies reporting the TP53 p.R337H mutation as founder mutation in Southern and Southeastern Brazil, there has been controversy on its origin. Preliminary analysis of a small subset of Brazilian mutation carriers revealed that the haplotype incided on a Caucasian background. The vast majority of carriers identified today reside in Brazil or, if identified in other countries, are Brazilian immigrants. To our knowledge, the only two exceptions of carriers without a recognizable link with Brazil are two European families, from Portugal and Germany. Haplotype analysis in the Portuguese family revealed the same haplotype identified in Brazilian individuals, but in the German family, a distinct haplotype was found. Knowing that a significant proportion of women with breast cancer (BC) in Southern Brazil are p.R337H carriers, we analyzed p.R337H in a Portuguese cohort of women diagnosed with this disease. Median age at diagnosis among the first 573 patients tested was 60 years and 100 (17.4%) patients had been diagnosed at or under the age of 45 years. Mutation screening failed to identify the mutation in the 573 patients tested. These results are in contrast with the mutation frequency observed in a study including 815 BC-affected women from Brazil, in which carrier frequencies of 12.1 and 5.1% in pre- and postmenopausal women were observed, respectively. These findings suggest that the Brazilian founder mutation p.R337H, the most frequent germline TP53 mutation reported to date, is not a common germline alteration in Portuguese women diagnosed with BC.
Asunto(s)
Neoplasias de la Mama/genética , Predisposición Genética a la Enfermedad , Mutación , Proteína p53 Supresora de Tumor/genética , Adulto , Femenino , Humanos , Síndrome de Li-Fraumeni/genética , Persona de Mediana Edad , Portugal , Población BlancaRESUMEN
Aneuploidy has been strongly linked to cancer development, and published evidence has suggested that aneuploidy can have an oncogenic or a tumor suppressor role depending on the tissue context. Using the Drosophila midgut as a model, we have recently described that adult intestinal stem cells (ISCs), do not activate programmed cell death upon aneuploidy induction, leading to an increase in ISC proliferation rate, and tissue dysplasia. How aneuploidy impacts ISCs in intestinal tumorigenic models remains to be investigated, and it represents a very important biological question to address since data from multiple in vivo models suggests that the cellular impact of aneuploidy is highly dependent on the cellular and tissue context. Using manipulation of different genetic pathways such as EGFR, JAK-STAT and Notch that cause dysplastic phenotypes in the Drosophila gut, we found that concomitant aneuploidy induction by impairment of the spindle assembly checkpoint (SAC) consistently leads to a more severe progression of intestinal dysplasia or tumorigenesis. This is characterized by an accumulation of progenitor cells, high tissue cell density and higher stem cell proliferation rates, revealing an additive or synergistic effect depending on the misregulated pathway in which aneuploidy was induced. Thus, our data suggests that in the Drosophila gut, both dysplasia and tumorigenic phenotypes can be fueled by inducing genomic instability of resident stem cells.
Asunto(s)
Aneuploidia , Carcinogénesis/genética , Drosophila/genética , Neoplasias Intestinales/genética , Lesiones Precancerosas/genética , Animales , Apoptosis/genética , Proliferación Celular/genética , Intestinos/metabolismo , Fenotipo , Células Madre/metabolismoRESUMEN
The cytoskeleton protein α-fodrin plays a major role in maintaining structural stability of membranes. It was also identified as part of the brain γ-tubulin ring complex, the major microtubule nucleator. Here, we investigated the requirement of α-fodrin for microtubule spindle assembly during mitotic progression. We found that α-fodrin depletion results in abnormal mitosis with uncongressed chromosomes, leading to prolonged activation of the spindle assembly checkpoint and a severe mitotic delay. Further, α-fodrin repression led to the formation of shortened spindles with unstable kinetochore-microtubule attachments. We also found that the mitotic kinesin CENP-E had reduced levels at kinetochores to likely account for the chromosome misalignment defects in α-fodrin-depleted cells. Importantly, we showed these cells to exhibit reduced levels of detyrosinated α-tubulin, which primarily drives CENP-E localization. Since proper microtubule dynamics and chromosome alignment are required for completion of normal mitosis, this study reveals an unforeseen role of α-fodrin in regulating mitotic progression. Future studies on these lines of observations should reveal important mechanistic insight for fodrin's involvement in cancer.
Asunto(s)
Proteínas Portadoras/metabolismo , Proteínas Cromosómicas no Histona/metabolismo , Puntos de Control de la Fase M del Ciclo Celular/genética , Proteínas de Microfilamentos/metabolismo , Microtúbulos/metabolismo , Mitosis/genética , Proteínas Portadoras/genética , Línea Celular Tumoral , Proteínas Cromosómicas no Histona/genética , Segregación Cromosómica , Humanos , Cinetocoros/metabolismo , Proteínas de Microfilamentos/genética , ARN Interferente Pequeño , Huso Acromático/metabolismo , Tubulina (Proteína)/metabolismo , Tirosina/metabolismoRESUMEN
Aneuploidy is associated with different human diseases including cancer. However, different cell types appear to respond differently to aneuploidy, either by promoting tumorigenesis or causing cell death. We set out to study the behavior of adult Drosophila melanogaster intestinal stem cells (ISCs) after induction of chromosome missegregation either by abrogation of the spindle assembly checkpoint or through kinetochore disruption or centrosome amplification. These conditions induce moderate levels of aneuploidy in ISCs, and we find no evidence of apoptosis. Instead, we observe a significant accumulation of ISCs associated with increased stem cell proliferation and an excess of enteroendocrine cells. Moreover, aneuploidy causes up-regulation of the JNK pathway throughout the posterior midgut, and specific inhibition of JNK signaling in ISCs is sufficient to prevent dysplasia. Our findings highlight the importance of understanding the behavior of different stem cell populations to aneuploidy and how these can act as reservoirs for genomic alterations that can lead to tissue pathologies.