RESUMO
Integration of transposable elements into the genome is mutagenic. Mechanisms targeting integrations into relatively safe locations, hence minimizing deleterious consequences for cell fitness, have emerged during evolution. In budding yeast, integration of the Ty1 LTR retrotransposon upstream of RNA polymerase III (Pol III)-transcribed genes requires interaction between Ty1 integrase (IN1) and AC40, a subunit common to Pol I and Pol III. Here, we identify the Ty1 targeting domain of IN1 that ensures (i) IN1 binding to Pol I and Pol III through AC40, (ii) IN1 genome-wide recruitment to Pol I- and Pol III-transcribed genes, and (iii) Ty1 integration only at Pol III-transcribed genes, while IN1 recruitment by AC40 is insufficient to target Ty1 integration into Pol I-transcribed genes. Swapping the targeting domains between Ty5 and Ty1 integrases causes Ty5 integration at Pol III-transcribed genes, indicating that the targeting domain of IN1 alone confers Ty1 integration site specificity.
Assuntos
Integrases/metabolismo , RNA Polimerase III/metabolismo , RNA Polimerase I/metabolismo , RNA de Transferência/genética , Retroelementos , Proteínas de Saccharomyces cerevisiae/metabolismo , Saccharomyces cerevisiae/metabolismo , Integrases/genética , RNA Polimerase I/genética , RNA Polimerase III/genética , Saccharomyces cerevisiae/genética , Proteínas de Saccharomyces cerevisiae/genéticaRESUMO
The aim of this study was to better define the clinical and biopathological features of patients with desmoplastic/nodular medulloblastoma (DNMB) and to further characterize this subgroup. 17 children aged < 5 years, with initial DNMB treated according to the HIT-SKK protocol, were evaluated. A retrospective central radiological review, a pathological and immunohistochemical study, and array-CGH and sequencing of germline SUFU and PTCH1 genes were performed. 15 histologically reviewed cases were confirmed as DNMB including three cases of medulloblastoma with extensive nodularity. Median age at diagnosis was 26 months. Radiology showed five cases with a vermis location and one with T2 hyperintensity. All cases showed a SHH immunoprofile. A 9q deletion was found in 6 cases, a MYCN-MYCL amplification in 1 case, and a SUFU germline mutation in 1 case (/9). The presence of SUFU and PTCH1 germline mutations agreed with previous reports. At 3 years, progression-free survival and overallsurvival rates were 72 ± 15% and 85 ± 10%, respectively. The rate of recurrence was relatively high (4 patients). This may have been because chemotherapy was delayed in two cases. Age > 3 years, and residual tumor may also have been an explanation for recurrence.
Assuntos
Neoplasias Cerebelares/patologia , Meduloblastoma/genética , Meduloblastoma/patologia , Biomarcadores Tumorais/análise , Neoplasias Cerebelares/genética , Neoplasias Cerebelares/mortalidade , Pré-Escolar , Feminino , Humanos , Imuno-Histoquímica , Lactente , Estimativa de Kaplan-Meier , Masculino , Meduloblastoma/mortalidade , Mutação , Estudos RetrospectivosRESUMO
Medulloblastomas (MB) are classified in four subgroups: the well defined WNT and Sonic Hedgehog (SHH) subgroups, and the less defined groups 3 and 4. They occasionally occur in the context of a cancer predisposition syndrome. While germline APC mutations predispose to WNT MB, germline mutations in SUFU, PTCH1, and TP53 predispose to SHH tumors. We report on a child with a Rubinstein-Taybi syndrome (RTS) due to a germline deletion in CREBBP, who developed a MB. Biological profilings demonstrate that this tumor belongs to the group 3. RTS may therefore be the first predisposition syndrome identified for non-WNT/non-SHH MB.
Assuntos
Proteína de Ligação a CREB/genética , Neoplasias Cerebelares/etiologia , Predisposição Genética para Doença , Mutação em Linhagem Germinativa/genética , Meduloblastoma/etiologia , Síndrome de Rubinstein-Taybi/complicações , Neoplasias Cerebelares/patologia , Hibridização Genômica Comparativa , Proteínas Hedgehog/genética , Humanos , Lactente , Masculino , Meduloblastoma/patologia , Prognóstico , Síndrome de Rubinstein-Taybi/genética , Síndrome de Rubinstein-Taybi/patologia , Deleção de Sequência , Proteínas Wnt/genéticaRESUMO
AIMS: Renal medullary carcinoma (RMC), a rare and highly aggressive tumour which occurs in patients with sickle-cell disease, shares many clinicopathological features with collecting duct carcinoma (CDC). The molecular mechanisms underlying RMC and CDC are mainly unknown, and there is ongoing debate about their status as distinct entities. Loss of expression of SMARCB1/INI1, a chromatin remodelling regulator and repressor of cyclin D1 transcription, has been reported recently in RMC. The aim of our study was to investigate if such loss of expression is specific for RMC. SMARCB1/INI1 genetic alterations and cyclin D1 expression were also studied. METHODS AND RESULTS: Using immunochemistry, neoplastic cells showed complete loss of SMARCB1/INI1 expression in all six cases of RMC but in only one of 22 cases of CDC. In two RMC cases investigated, comparative genomic hybridization demonstrated complete loss of one SMARCB1/INI1 allele, with no other genomic imbalances, and no mutations were found on the remaining allele. Cyclin D1 was expressed in all RMCs, suggesting that SMARCB1/INI1 inactivation may result in increased cyclin D1 transcription. CONCLUSIONS: The specific SMARCB1/INI1 inactivation observed in RMCs suggests that RMC and CDC are different entities.
Assuntos
Carcinoma Medular/genética , Carcinoma de Células Renais/genética , Proteínas Cromossômicas não Histona/genética , Proteínas de Ligação a DNA/genética , Neoplasias Renais/genética , Fatores de Transcrição/genética , Adulto , Idoso , Idoso de 80 Anos ou mais , Carcinoma Ductal/genética , Carcinoma Ductal/metabolismo , Carcinoma Medular/metabolismo , Carcinoma de Células Renais/metabolismo , Proteínas Cromossômicas não Histona/análise , Proteínas Cromossômicas não Histona/biossíntese , Hibridização Genômica Comparativa , Proteínas de Ligação a DNA/análise , Proteínas de Ligação a DNA/biossíntese , Humanos , Imuno-Histoquímica , Hibridização in Situ Fluorescente , Neoplasias Renais/metabolismo , Pessoa de Meia-Idade , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Proteína SMARCB1 , Fatores de Transcrição/análise , Fatores de Transcrição/biossínteseAssuntos
Neoplasias Cerebelares/genética , Meduloblastoma/genética , Receptor Tipo 2 de Fator de Crescimento de Fibroblastos/genética , Receptor Tipo 3 de Fator de Crescimento de Fibroblastos/genética , Adulto , Sequência de Bases , Neoplasias Cerebelares/mortalidade , Pré-Escolar , Análise Mutacional de DNA , Feminino , Expressão Gênica , Estudos de Associação Genética , Mutação em Linhagem Germinativa , Humanos , Masculino , Meduloblastoma/mortalidade , Mutação de Sentido Incorreto , Receptor Tipo 2 de Fator de Crescimento de Fibroblastos/metabolismo , Receptor Tipo 3 de Fator de Crescimento de Fibroblastos/metabolismoRESUMO
Rhabdoid tumours (RTs) are highly aggressive tumours of infancy, frequently localized in the central nervous system (CNS) where they are termed atypical teratoid/rhabdoid tumours (AT/RTs) and characterized by bi-allelic inactivation of the SMARCB1 tumour suppressor gene. In this study, by temporal control of tamoxifen injection in Smarcb1(flox/flox);Rosa26-Cre(ERT2) mice, we explore the phenotypes associated with Smarcb1 inactivation at different developmental stages. Injection before E6, at birth or at 2 months of age recapitulates previously described phenotypes including embryonic lethality, hepatic toxicity or development of T-cell lymphomas, respectively. Injection between E6 and E10 leads to high penetrance tumours, mainly intra-cranial, with short delays (median: 3 months). These tumours demonstrate anatomical, morphological and gene expression profiles consistent with those of human AT/RTs. Moreover, intra- and inter-species comparisons of tumours reveal that human and mouse RTs can be split into different entities that may underline the variety of RT cells of origin.
Assuntos
Neoplasias Encefálicas/genética , Proteínas Cromossômicas não Histona/genética , Tumor Rabdoide/genética , Animais , Neoplasias Encefálicas/induzido quimicamente , Neoplasias Encefálicas/metabolismo , Pré-Escolar , Proteínas Cromossômicas não Histona/metabolismo , Proteínas de Ligação a DNA/genética , Proteínas de Ligação a DNA/metabolismo , Feminino , Regulação Neoplásica da Expressão Gênica , Inativação Gênica , Humanos , Masculino , Camundongos , Tumor Rabdoide/induzido quimicamente , Tumor Rabdoide/metabolismo , Proteína SMARCB1 , Tamoxifeno/toxicidade , Fatores de Transcrição/genética , Fatores de Transcrição/metabolismoRESUMO
The present study describes a new case of EWSR1-negative undifferentiated sarcoma with CIC/DUX4 gene fusion. This case is similar to tumors described as primitive undifferentiated round cell sarcomas that occur mainly in the trunk and display an aggressive behavior. To our knowledge, this is the first report of such a tumor presenting locoregional lymph node metastasis. In view of previous studies that prove the existence of a particular variant of undifferentiated sarcoma with Ewing-like morphology and CIC/DUX-4 gene fusion, a search for this gene fusion in all undifferentiated round cell sarcomas should be considered if a conclusive diagnosis cannot be reached following other conventional studies. Although additional cases with more extensive follow-up studies are needed, we believe that EWSR1-negative undifferentiated small round cell sarcoma with CIC/DUX4 gene fusion should be added to the list of new sarcoma variants with the possibility of lymph node metastasis.
Assuntos
Proteínas de Ligação a Calmodulina/genética , Proteínas de Homeodomínio/genética , Proteínas de Ligação a RNA/genética , Proteínas Repressoras/genética , Sarcoma de Células Pequenas/genética , Sarcoma de Células Pequenas/patologia , Humanos , Imuno-Histoquímica , Hibridização in Situ Fluorescente , Metástase Linfática/genética , Metástase Linfática/patologia , Masculino , Proteínas de Fusão Oncogênica/genética , Proteína EWS de Ligação a RNA , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Adulto JovemRESUMO
As prognostic factors, MYC and MYCN amplifications are routinely assessed in medulloblastomas. Fluorescence in situ hybridization (FISH) is currently considered as the technique of reference. Recently, array comparative genomic hybridization (aCGH) has been developed as an alternative technique to evaluate genomic abnormalities in other tumor types; however, this technique has not been widely adopted as a replacement for FISH in medulloblastoma. In this study, 34 tumors were screened by both FISH and aCGH. In all cases showing amplification by FISH, aCGH also unambiguously revealed the abnormality. The aCGH technique was also performed on tumors showing no amplification by FISH, and the absence of amplification was confirmed in all cases. Interestingly, one tumor showed a subclonal MYC amplification by FISH. This subclonal amplification was observed in approximately 20% of tumor cells and was clearly evident on aCGH. In conclusion, our analysis confirms that aCGH is as safe as FISH for the detection of MYC/MYCN gene amplification. Given its cost efficiency in comparison to two FISH tests and the global genomic information additionally provided by an aCGH experiment, this reproducible technique can be safely retained as an alternative to FISH for routine investigation of medulloblastoma.