RESUMEN
BRCA2 tumor suppressor protein ensures genome integrity by mediating DNA repair via homologous recombination (HR). This function is executed in part by its canonical DNA binding domain located at the C-terminus (BRCA2CTD), the only folded domain of the protein. Most germline pathogenic missense variants are located in this highly conserved region which binds to single-stranded DNA (ssDNA) and to the acidic protein DSS1. These interactions are essential for the HR function of BRCA2. Here, we report that the variant R2645G, identified in breast cancer and located at the DSS1 interface, unexpectedly increases the ssDNA binding activity of BRCA2CTDin vitro. Human cells expressing this variant display a hyper-recombination phenotype, chromosomal instability in the form of chromatid gaps when exposed to DNA damage, and increased PARP inhibitor sensitivity. In mouse embryonic stem cells (mES), this variant alters viability and confers sensitivity to cisplatin and Mitomycin C. These results suggest that BRCA2 interaction with ssDNA needs to be tightly regulated to limit HR and prevent chromosomal instability and we propose that this control mechanism involves DSS1. Given that several missense variants located within this region have been identified in breast cancer patients, these findings might have clinical implications for carriers.
Asunto(s)
Proteína BRCA2 , ADN de Cadena Simple , Unión Proteica , Humanos , Proteína BRCA2/genética , Proteína BRCA2/metabolismo , Animales , Ratones , ADN de Cadena Simple/metabolismo , ADN de Cadena Simple/genética , Inestabilidad Cromosómica , Neoplasias de la Mama/genética , Neoplasias de la Mama/metabolismo , Cisplatino/farmacología , Daño del ADN , Mutación Missense , Femenino , Inhibidores de Poli(ADP-Ribosa) Polimerasas/farmacología , Células Madre Embrionarias de Ratones/metabolismo , Línea Celular Tumoral , Mitomicina/farmacología , Proteínas de Unión al ADN/metabolismo , Proteínas de Unión al ADN/genética , Complejo de la Endopetidasa ProteasomalRESUMEN
BACKGROUND: CDH1 and CTNNA1 remain as the main genes for hereditary gastric cancer. However, they only explain a small fraction of gastric cancer cases with suspected inherited basis. In this study, we aimed to identify new hereditary genes for early-onset gastric cancer patients (EOGC; < 50 years old). METHODS: After germline exome sequencing in 20 EOGC patients and replication of relevant findings by gene-panel sequencing in an independent cohort of 152 patients, CTNND1 stood out as an interesting candidate gene, since its protein product (p120ctn) directly interacts with E-cadherin. We proceeded with functional characterization by generating two knockout CTNND1 cellular models by gene editing and introducing the detected genetic variants using a lentiviral delivery system. We assessed ß-catenin and E-cadherin levels, cell detachment, as well as E-cadherin localization and cell-to-cell interaction by spheroid modeling. RESULTS: Three CTNND1 germline variants [c.28_29delinsCT, p.(Ala10Leu); c.1105C > T, p.(Pro369Ser); c.1537A > G, p.(Asn513Asp)] were identified in our EOGC cohorts. Cells encoding CTNND1 variants displayed altered E-cadherin levels and intercellular interactions. In addition, the p.(Pro369Ser) variant, located in a key region in the E-cadherin/p120ctn binding domain, showed E-cadherin mislocalization. CONCLUSIONS: Defects in CTNND1 could be involved in germline predisposition to gastric cancer by altering E-cadherin and, consequently, cell-to-cell interactions. In the present study, CTNND1 germline variants explained 2% (3/172) of the cases, although further studies in larger external cohorts are needed.
Asunto(s)
Cadherinas , Cateninas , Catenina delta , Predisposición Genética a la Enfermedad , Mutación de Línea Germinal , Neoplasias Gástricas , Neoplasias Gástricas/genética , Neoplasias Gástricas/patología , Humanos , Masculino , Cateninas/genética , Cateninas/metabolismo , Femenino , Persona de Mediana Edad , Adulto , Cadherinas/genética , Comunicación Celular , Edad de Inicio , Antígenos CDRESUMEN
Cutaneous neurofibromas (cNFs) are benign Schwann cell (SC) tumors arising from subepidermal glia. Individuals with neurofibromatosis type 1 (NF1) may develop thousands of cNFs, which greatly affect their quality of life. cNF growth is driven by the proliferation of NF1-/- SCs and their interaction with the NF1+/- microenvironment. We analyzed the crosstalk between human cNF-derived SCs and fibroblasts (FBs), identifying an expression signature specific to the SC-FB interaction. We validated the secretion of proteins involved in immune cell migration, suggesting a role of SC-FB crosstalk in immune cell recruitment. The signature also captured components of developmental signaling pathways, including the cAMP elevator G protein-coupled receptor 68 (GPR68). Activation of Gpr68 by ogerin in combination with the MEK inhibitor (MEKi) selumetinib reduced viability and induced differentiation and death of human cNF-derived primary SCs, a result corroborated using an induced pluripotent stem cell-derived 3D neurofibromasphere model. Similar results were obtained using other Gpr68 activators or cAMP analogs/adenylyl cyclase activators in combination with selumetinib. Interestingly, whereas primary SC cultures restarted their proliferation after treatment with selumetinib alone was stopped, the combination of ogerin-selumetinib elicited a permanent halt on SC expansion that persisted after drug removal. These results indicate that unbalancing the Ras and cAMP pathways by combining MEKi and cAMP elevators could be used as a potential treatment for cNFs.
Asunto(s)
Neurofibroma , Neurofibromatosis 1 , Neoplasias Cutáneas , Triazinas , Humanos , Calidad de Vida , Neurofibroma/tratamiento farmacológico , Neurofibromatosis 1/tratamiento farmacológico , Neurofibromatosis 1/patología , Alcoholes Bencílicos , Neoplasias Cutáneas/patología , Inhibidores de Proteínas Quinasas/farmacología , Microambiente Tumoral , Receptores Acoplados a Proteínas GRESUMEN
BACKGROUND: Up to 70% of suspected Lynch syndrome patients harboring MMR deficient tumors lack identifiable germline pathogenic variants in MMR genes, being referred to as Lynch-like syndrome (LLS). Previous studies have reported biallelic somatic MMR inactivation in a variable range of LLS-associated tumors. Moreover, translating tumor testing results into patient management remains controversial. Our aim is to assess the challenges associated with the implementation of tumoral MMR gene testing in routine workflows. METHODS: Here, we present the clinical characterization of 229 LLS patients. MMR gene testing was performed in 39 available tumors, and results were analyzed using two variant allele frequency (VAF) thresholds (≥5% and ≥10%). RESULTS AND DISCUSSION: More biallelic somatic events were identified at VAF ≥ 5% than ≥10% (35.9% vs. 25.6%), although the rate of nonconcordant results regarding immunohistochemical pattern increased (30.8% vs. 20.5%). Interpretation difficulties question the current utility of the identification of MMR somatic hits in the diagnostic algorithm of suspected LS cases.
Asunto(s)
Neoplasias Encefálicas , Neoplasias Colorrectales Hereditarias sin Poliposis , Neoplasias Colorrectales , Síndromes Neoplásicos Hereditarios , Humanos , Neoplasias Colorrectales/genética , Neoplasias Colorrectales Hereditarias sin Poliposis/diagnóstico , Neoplasias Colorrectales Hereditarias sin Poliposis/genética , Neoplasias Colorrectales Hereditarias sin Poliposis/patología , Mutación de Línea Germinal , Reparación de la Incompatibilidad de ADN/genéticaRESUMEN
The molecular diagnosis of mismatch repair-deficient cancer syndromes is hampered by difficulties in sequencing the PMS2 gene, mainly owing to the PMS2CL pseudogene. Next-generation sequencing short reads cannot be mapped unambiguously by standard pipelines, compromising variant calling accuracy. This study aimed to provide a refined bioinformatic pipeline for PMS2 mutational analysis and explore PMS2 germline pathogenic variant prevalence in an unselected hereditary cancer (HC) cohort. PMS2 mutational analysis was optimized using two cohorts: 192 unselected HC patients for assessing the allelic ratio of paralogous sequence variants, and 13 samples enriched with PMS2 (likely) pathogenic variants screened previously by long-range genomic DNA PCR amplification. Reads were forced to align with the PMS2 reference sequence, except those corresponding to exon 11, where only those intersecting gene-specific invariant positions were considered. Afterward, the refined pipeline's accuracy was validated in a cohort of 40 patients and used to screen 5619 HC patients. Compared with our routine diagnostic pipeline, the PMS2_vaR pipeline showed increased technical sensitivity (0.853 to 0.956, respectively) in the validation cohort, identifying all previously PMS2 pathogenic variants found by long-range genomic DNA PCR amplification. Fifteen HC cohort samples carried a pathogenic PMS2 variant (15 of 5619; 0.285%), doubling the estimated prevalence in the general population. The refined open-source approach improved PMS2 mutational analysis accuracy, allowing its inclusion in the routine next-generation sequencing pipeline streamlining PMS2 screening.
Asunto(s)
Biología Computacional , Pruebas Genéticas , Secuenciación de Nucleótidos de Alto Rendimiento , Endonucleasa PMS2 de Reparación del Emparejamiento Incorrecto , Humanos , Endonucleasa PMS2 de Reparación del Emparejamiento Incorrecto/genética , Secuenciación de Nucleótidos de Alto Rendimiento/métodos , Biología Computacional/métodos , Pruebas Genéticas/métodos , Análisis Mutacional de ADN/métodos , Mutación de Línea Germinal , Síndromes Neoplásicos Hereditarios/genética , Síndromes Neoplásicos Hereditarios/diagnósticoRESUMEN
BACKGROUND: Hereditary leiomyomatosis and renal cell cancer syndrome is a rare autosomal dominant hereditary syndrome. Previously, we published the largest cohort of FH mutation carriers in Spain and observed a highly recurrent missense heterozygous variant, FH(NM_000143.4):c.1118A > G p.(Asn373Ser), in 104 individuals from 31 apparently unrelated families. Here, we aimed to establish its founder effect and characterize the associated clinical phenotype. RESULTS: Haplotype analysis confirmed that families shared a common haplotype (32/38 markers) spanning 0.61-0.82 Mb, indicating this recurrent variant was inherited from a founder ancestor. Cutaneous and uterine leiomyomatosis were diagnosed in 64.6% (64/99) and 98% (50/51) of patients, respectively, and renal cell cancer was present in 10.4% (10/96). The pathogenic FH_c.1118A > G variant is a Spanish founder mutation that originated 12-26 generations ago. We estimate that the variant may have appeared between 1370 and 1720. Individuals carrying this founder mutation had similar frequency of renal cell cancer and a higher frequency of renal cysts and leiomyomas than those in other cohorts of this syndrome. CONCLUSIONS: In the Spanish province of Alicante there is a high prevalence of HLRCC because of the founder mutation FH c.1118A > G; p.(Asn373Ser). The characterization of founder mutations provides accurate and specific information regarding their penetrance and expressivity. In individuals with suspected HLRCC from the province of Alicante, genetic testing by direct analysis of the founder FH c.1118A > G; p.(Asn373Ser) mutation may be a faster and more efficient diagnostic tool compared with complete gene sequencing.
Asunto(s)
Carcinoma de Células Renales , Neoplasias Renales , Leiomiomatosis , Síndromes Neoplásicos Hereditarios , Neoplasias Cutáneas , Neoplasias Uterinas , Femenino , Humanos , Leiomiomatosis/genética , Leiomiomatosis/patología , Neoplasias Renales/genética , Neoplasias Cutáneas/patología , Mutación/genética , SíndromeRESUMEN
PURPOSE: Establishing accurate age-related penetrance figures for the broad range of cancer types that occur in individuals harboring a pathogenic germline variant in the TP53 gene is essential to determine the most effective clinical management strategies. These figures also permit optimal use of cosegregation data for classification of TP53 variants of unknown significance. Penetrance estimation can easily be affected by bias from ascertainment criteria, an issue not commonly addressed by previous studies. MATERIALS AND METHODS: We performed a maximum likelihood penetrance estimation using full pedigree data from a multicenter study of 146 TP53-positive families, incorporating adjustment for the effect of ascertainment and population-specific background cancer risks. The analysis included pedigrees from Australia, Spain, and United States, with phenotypic information for 4,028 individuals. RESULTS: Core Li-Fraumeni syndrome (LFS) cancers (breast cancer, adrenocortical carcinoma, brain cancer, osteosarcoma, and soft tissue sarcoma) had the highest hazard ratios of all cancers analyzed in this study. The analysis also detected a significantly increased lifetime risk for a range of cancers not previously formally associated with TP53 pathogenic variant status, including colorectal, gastric, lung, pancreatic, and ovarian cancers. The cumulative risk of any cancer type by age 50 years was 92.4% (95% CI, 82.2 to 98.3) for females and 59.7% (95% CI, 39.9 to 81.3) for males. Females had a 63.3% (95% CI, 35.6 to 90.1) cumulative risk of developing breast cancer by age 50 years. CONCLUSION: The results from maximum likelihood analysis confirm the known high lifetime risk for the core LFS-associated cancer types providing new risk estimates and indicate significantly increased lifetime risks for several additional cancer types. Accurate cancer risk estimates will help refine clinical recommendations for TP53 pathogenic variant carriers and improve TP53 variant classification.
Asunto(s)
Neoplasias de la Mama , Síndrome de Li-Fraumeni , Masculino , Femenino , Humanos , Estados Unidos , Persona de Mediana Edad , Síndrome de Li-Fraumeni/diagnóstico , Síndrome de Li-Fraumeni/genética , Genes p53/genética , Linaje , Proteína p53 Supresora de Tumor/genética , Predisposición Genética a la Enfermedad/genética , Neoplasias de la Mama/genética , Factores de RiesgoRESUMEN
BACKGROUND: The immune system has a central role in preventing carcinogenesis. Alteration of systemic immune cell levels may increase cancer risk. However, the extent to which common genetic variation influences blood traits and cancer risk remains largely undetermined. Here, we identify pleiotropic variants and predict their underlying molecular and cellular alterations. METHODS: Multivariate Cox regression was used to evaluate associations between blood traits and cancer diagnosis in cases in the UK Biobank. Shared genetic variants were identified from the summary statistics of the genome-wide association studies of 27 blood traits and 27 cancer types and subtypes, applying the conditional/conjunctional false-discovery rate approach. Analysis of genomic positions, expression quantitative trait loci, enhancers, regulatory marks, functionally defined gene sets, and bulk- and single-cell expression profiles predicted the biological impact of pleiotropic variants. Plasma small RNAs were sequenced to assess association with cancer diagnosis. RESULTS: The study identified 4093 common genetic variants, involving 1248 gene loci, that contributed to blood-cancer pleiotropism. Genomic hotspots of pleiotropism include chromosomal regions 5p15-TERT and 6p21-HLA. Genes whose products are involved in regulating telomere length are found to be enriched in pleiotropic variants. Pleiotropic gene candidates are frequently linked to transcriptional programs that regulate hematopoiesis and define progenitor cell states of immune system development. Perturbation of the myeloid lineage is indicated by pleiotropic associations with defined master regulators and cell alterations. Eosinophil count is inversely associated with cancer risk. A high frequency of pleiotropic associations is also centered on the regulation of small noncoding Y-RNAs. Predicted pleiotropic Y-RNAs show specific regulatory marks and are overabundant in the normal tissue and blood of cancer patients. Analysis of plasma small RNAs in women who developed breast cancer indicates there is an overabundance of Y-RNA preceding neoplasm diagnosis. CONCLUSIONS: This study reveals extensive pleiotropism between blood traits and cancer risk. Pleiotropism is linked to factors and processes involved in hematopoietic development and immune system function, including components of the major histocompatibility complexes, and regulators of telomere length and myeloid lineage. Deregulation of Y-RNAs is also associated with pleiotropism. Overexpression of these elements might indicate increased cancer risk.
Asunto(s)
Estudio de Asociación del Genoma Completo , Neoplasias , Humanos , Femenino , Fenotipo , Sitios de Carácter Cuantitativo , Pleiotropía Genética , Neoplasias/genética , Polimorfismo de Nucleótido Simple , Predisposición Genética a la EnfermedadRESUMEN
Accurate classification of genetic variants is crucial for clinical decision-making in hereditary cancer. In Spain, genetic diagnostic laboratories have traditionally approached this task independently due to the lack of a dedicated resource. Here we present SpadaHC, a web-based database for sharing variants in hereditary cancer genes in the Spanish population. SpadaHC is implemented using a three-tier architecture consisting of a relational database, a web tool and a bioinformatics pipeline. Contributing laboratories can share variant classifications and variants from individuals in Variant Calling Format (VCF) format. The platform supports open and restricted access, flexible dataset submissions, automatic pseudo-anonymization, VCF quality control, variant normalization and liftover between genome builds. Users can flexibly explore and search data, receive automatic discrepancy notifications and access SpadaHC population frequencies based on many criteria. In February 2024, SpadaHC included 18 laboratory members, storing 1.17 million variants from 4306 patients and 16 343 laboratory classifications. In the first analysis of the shared data, we identified 84 genetic variants with clinically relevant discrepancies in their classifications and addressed them through a three-phase resolution strategy. This work highlights the importance of data sharing to promote consistency in variant classifications among laboratories, so patients and family members can benefit from more accurate clinical management. Database URL: https://spadahc.ciberisciii.es/.
Asunto(s)
Bases de Datos Genéticas , Humanos , España , Variación Genética , Neoplasias/genética , Genes Relacionados con las Neoplasias , Predisposición Genética a la EnfermedadRESUMEN
El diagnóstico genético de los síndromes de cáncer hereditario ofrece la oportunidad de establecer unas medidas de predicción/prevención eficaces en el paciente y sus familiares que se traducen en una disminución de la morbimortalidad por cáncer en las familias de alto riesgo genético. La secuenciación masiva (NGS) ofrece una considerable mejora de la eficiencia del diagnóstico genético, permitiendo un aumento del rendimiento diagnóstico con una reducción sustancial del tiempo de respuesta y costes económicos. En consecuencia, la implementación de esta nueva tecnología es una gran oportunidad de mejora en el manejo clínico de las familias afectas. El objetivo de la presente guía es establecer un marco de recomendaciones útiles para una implementación planificada y controlada de la NGS en el contexto de la predisposición hereditaria a cáncer, que permita potenciar las fortalezas y oportunidades que ofrece dicha tecnología y minimizar las debilidades y amenazas que puedan derivarse de su uso. Está inspirada en las recomendaciones de sociedades internacionales, habiendo sido adaptada a nuestro entorno, y teniendo en cuenta aspectos coyunturales a nivel organizativo y biojurídico. Se aportan 41 declaraciones agrupadas en 6 apartados: utilidad clínica y diagnóstica, consentimiento informado y asesoramiento genético pretest y postest, validación de los procedimientos analíticos, informe de resultados, gestión de la información y distinción entre ámbito de investigación y ámbito asistencial. Esta guía ha sido elaborada por la Asociación Española de Genética Humana (AEGH), la Sociedad Española de Medicina de Laboratorio (SEQC-ML) y la Sociedad Española de Oncología Médica (SEOM)
Genetic diagnosis of hereditary cancer syndromes offers the opportunity to establish more effective predictive and preventive measures for the patient and their families. The ultimate objective is to decrease cancer morbidity and mortality in high genetic risk families. Next Generation Sequencing (NGS) offers an important improvement in the efficiency of genetic diagnosis, allowing an increase in diagnostic yield with a substantial reduction in response times and economic costs. Consequently, the implementation of this new technology is a great opportunity for improvement in the clinical management of affected families. The aim of these guidelines is to establish a framework of useful recommendations for planned and controlled implementation of NGS in the context of hereditary cancer. These will help to consolidate the strengths and opportunities offered by this technology, and minimise the weaknesses and threats which may derive from its use. The recommendations of international societies have been adapted to our environment, taking the Spanish context into account at organisational and juridical levels. Forty-one statements are grouped under six headings: clinical and diagnostic utility, informed consent and genetic counselling pre-test and post-test, validation of analytical procedures, results report, management of information and distinction between research and clinical context. This guide has been developed by the Spanish Association of Human Genetics (AEGH), the Spanish Society of Laboratory Medicine (SEQC-ML) and the Spanish Society of Medical Oncology (SEOM)
Asunto(s)
Neoplasias/genética , Análisis de Secuencia/métodos , Neoplasias/diagnóstico , Pruebas Genéticas/métodos , Guías de Práctica Clínica como AsuntoRESUMEN
FUNDAMENTO: Identificación de las regiones de predisposición a psoriasis en población española. Estudio de las regiones 6p, 17q, 4q y 1cenq21. PACIENTES Y MÉTODO: Análisis de un grupo de 27 familias de origen español con psoriasis. Estudio con 22 marcadores microsatélites mediante análisis de ligamiento de las regiones candidatas con métodos paramétricos y no paramétricos. RESULTADOS: Evidencia de ligamiento (p < 0,05) mediante métodos no paramétricos en la región 6p. Ausencia de ligamiento en las regiones 17q, 4q y 1cen-q21. CONCLUSIÓN: Se demuestra la importancial del locus PSORS1 (6p21.3) como causante de psoriasis en la población española (AU)