RESUMEN
In schwannomatosis, germline SMARCB1 or LZTR1 mutations predispose to the development of multiple benign schwannomas. Besides these, other tumors may occur in schwannomatosis patients. We present a 45-year-old male patient who developed multiple schwannomas and in addition a malignant type 1 papillary renal cell carcinoma (pRCC1). We identified a duplication of exon 7 of SMARCB1 on chromosome 22 in the constitutional DNA of the patient (c.796-2246_986 + 5250dup7686), resulting in the generation of a premature stop codon in the second exon 7 copy (p.Glu330*). The mutant SMARCB1 allele proved to be retained in three schwannomas and in the pRCC1 of the patient. Loss of heterozygosity analysis demonstrated partial loss of the wild-type SMARCB1 allele containing chromosome 22, suggesting loss of that chromosome in only a subset of tumor cells, in all four tumors. Immunohistochemical staining with a SMARCB1 antibody revealed a mosaic SMARCB1 expression pattern in the three benign schwannomas, but absence of expression in the malignant tumor cells of the pRCC1. To our knowledge, this difference in SMARCB1 protein expression has not been reported before. We conclude that a germline SMARCB1 mutation may predispose to the development of pRCC1, thereby further widening the spectrum of tumors that can develop in the context of schwannomatosis.
Asunto(s)
Proteínas Cromosómicas no Histona/genética , Proteínas de Unión al ADN/genética , Neoplasias Renales/genética , Neurilemoma/genética , Factores de Transcripción/genética , Carcinoma de Células Renales/genética , Cromosomas Humanos Par 22 , Perfilación de la Expresión Génica , Mutación de Línea Germinal , Humanos , Masculino , Persona de Mediana Edad , Proteína SMARCB1RESUMEN
Osteosarcomas are primary tumors of bone that most often develop in adolescents. They are characterized by complex genomic changes including amplifications, deletions, and translocations. The chromosome region 17p11.2p12 is frequently amplified in human high grade osteosarcomas (25% of cases), suggesting the presence of one or more oncogenes. In previous studies, we identified 9 candidate oncogenes in this region (GID4, ARGHAP44, LRRC75A-AS1, TOP3A, COPS3, SHMT1, PRPSAP2, PMP22, and RASD1). The aim of the present study was to determine their oncogenic properties. Therefore, we generated osteosarcoma cell lines overexpressing these genes, except for LRRC75A-AS1 and PRPSAP2, and subjected these to functional oncogenic assays. We found that TOP3A, SHMT1, and RASD1 overexpression provided increased proliferation and that ARGHAP44, COPS3, and PMP22 overexpression had a stimulatory effect on migration and invasion of the cells. COPS3 and PMP22 overexpression additionally improved the ability of the cells to form new colonies. No oncogenic effect could be demonstrated for GID4 overexpression. We conclude that the concerted amplification-mediated overexpression of these genes in 17p11.2p12 may contribute to the oncogenic process in malignant osteosarcoma.
Asunto(s)
Cromosomas Humanos Par 17/genética , Oncogenes/genética , Osteosarcoma/genética , Osteosarcoma/patología , Complejo del Señalosoma COP9 , Línea Celular Tumoral , Movimiento Celular/genética , Proliferación Celular/genética , ADN-Topoisomerasas de Tipo I/genética , ADN-Topoisomerasas de Tipo I/metabolismo , Proteínas Activadoras de GTPasa/genética , Proteínas Activadoras de GTPasa/metabolismo , Glicina Hidroximetiltransferasa/genética , Glicina Hidroximetiltransferasa/metabolismo , Humanos , Proteínas de la Mielina/genética , Proteínas de la Mielina/metabolismo , Invasividad Neoplásica/genética , Proteínas Proto-Oncogénicas/genética , Proteínas Proto-Oncogénicas/metabolismo , Transfección , Proteínas ras/genética , Proteínas ras/metabolismoRESUMEN
In schwannomatosis, germline SMARCB1 mutations predispose to the development of multiple schwannomas, but not vestibular schwannomas. Many of these are missense or splice-site mutations or in-frame deletions, which are presumed to result in the synthesis of altered SMARCB1 proteins. However, also nonsense and frameshift mutations, which are characteristic for rhabdoid tumors and are predicted to result in the absence of SMARCB1 protein via nonsense-mediated mRNA decay, have been reported in schwannomatosis patients. We investigated the consequences of four of the latter mutations, i.e. c.30delC, c.34C>T, c.38delA, and c.46A>T, all in SMARCB1-exon 1. We could demonstrate for the c.30delC and c.34C>T mutations that the respective mRNAs were still present in the schwannomas of the patients. We hypothesized that these were prevented from degradation by translation reinitiation at the AUG codon encoding methionine at position 27 of the SMARCB1 protein. To test this, we expressed the mutations in MON cells, rhabdoid cells without endogenous SMARCB1 protein, and found that all four resulted in synthesis of the N-terminally truncated protein. Mutation of the reinitiation methionine codon into a valine codon prevented synthesis of the truncated protein, thereby confirming its identity. Immunohistochemistry with a SMARCB1 antibody revealed a mosaic staining pattern in schwannomas of the patients with the c.30delC and c.34C>T mutations. Our findings support the concept that, in contrast to the complete absence of SMARCB1 expression in rhabdoid tumors, altered SMARCB1 proteins with modified activity and reduced (mosaic) expression are formed in the schwannomas of schwannomatosis patients with a germline SMARCB1 mutation.
Asunto(s)
Proteínas Cromosómicas no Histona/genética , Proteínas Cromosómicas no Histona/metabolismo , Proteínas de Unión al ADN/genética , Proteínas de Unión al ADN/metabolismo , Mutación/genética , Neurilemoma/genética , Tumor Rabdoide/genética , Factores de Transcripción/genética , Factores de Transcripción/metabolismo , Línea Celular Tumoral , Análisis Mutacional de ADN , Femenino , Regulación Neoplásica de la Expresión Génica/genética , Humanos , Masculino , Persona de Mediana Edad , Mutagénesis Sitio-Dirigida , ARN Mensajero/metabolismo , Tumor Rabdoide/patología , Proteína SMARCB1 , TransfecciónRESUMEN
BACKGROUND: Glioblastoma is a highly malignant brain tumor for which no cure is available. To identify new therapeutic targets, we performed a mutation analysis of kinase genes in glioblastoma. METHODS: Database mining and a literature search identified 76 kinases that have been found to be mutated at least twice in multiple cancer types before. Among those we selected 34 kinase genes for mutation analysis. We also included IDH1, IDH2, PTEN, TP53 and NRAS, genes that are known to be mutated at considerable frequencies in glioblastoma. In total, 174 exons of 39 genes in 113 glioblastoma samples from 109 patients and 16 high-grade glioma (HGG) cell lines were sequenced. RESULTS: Our mutation analysis led to the identification of 148 non-synonymous somatic mutations, of which 25 have not been reported before in glioblastoma. Somatic mutations were found in TP53, PTEN, IDH1, PIK3CA, EGFR, BRAF, EPHA3, NRAS, TGFBR2, FLT3 and RPS6KC1. Mapping the mutated genes into known signaling pathways revealed that the large majority of them plays a central role in the PI3K-AKT pathway. CONCLUSIONS: The knowledge that at least 50% of glioblastoma tumors display mutational activation of the PI3K-AKT pathway should offer new opportunities for the rational development of therapeutic approaches for glioblastomas. However, due to the development of resistance mechanisms, kinase inhibition studies targeting the PI3K-AKT pathway for relapsing glioblastoma have mostly failed thus far. Other therapies should be investigated, targeting early events in gliomagenesis that involve both kinases and non-kinases.
Asunto(s)
Análisis Mutacional de ADN , Glioblastoma/enzimología , Glioblastoma/genética , Fosfotransferasas/genética , Adolescente , Adulto , Anciano , Anciano de 80 o más Años , Línea Celular Tumoral , Femenino , GTP Fosfohidrolasas/genética , Humanos , Isocitrato Deshidrogenasa/genética , Sistema de Señalización de MAP Quinasas , Masculino , Proteínas de la Membrana/genética , Persona de Mediana Edad , Mutación , Fosfohidrolasa PTEN/genética , Proteína p53 Supresora de Tumor/genética , Adulto JovenRESUMEN
Schwannomatosis is the third major form of neurofibromatosis and is characterized by the development of multiple schwannomas in the absence of bilateral vestibular schwannomas. The 2011 Schwannomatosis Update was organized by the Children's Tumor Foundation (www.ctf.org) and held in Los Angeles, CA, from June 5-8, 2011. This article summarizes the highlights presented at the Conference and represents the "state-of-the-field" in 2011. Genetic studies indicate that constitutional mutations in the SMARCB1 tumor suppressor gene occur in 40-50% of familial cases and in 8-10% of sporadic cases of schwannomatosis. Tumorigenesis is thought to occur through a four-hit, three-step model, beginning with a germline mutation in SMARCB1 (hit 1), followed by loss of a portion of chromosome 22 that contains the second SMARCB1 allele and one NF2 allele (hits 2 and 3), followed by mutation of the remaining wild-type NF2 allele (hit 4). Insights from research on HIV and pediatric rhabdoid tumors have shed light on potential molecular pathways that are dysregulated in schwannomatosis-related schwannomas. Mouse models of schwannomatosis have been developed and promise to further expand our understanding of tumorigenesis and the tumor microenvironment. Clinical reports have described the occurrence of intracranial meningiomas in schwannomatosis patients and in families with germline SMARCB1 mutations. The authors propose updated diagnostic criteria to incorporate new clinical and genetic findings since 2005. In the next 5 years, the authors expect that advances in basic research in the pathogenesis of schwannomatosis will lead toward clinical investigations of potential drug therapies.
Asunto(s)
Neurilemoma/genética , Neurofibromatosis/genética , Neoplasias Cutáneas/genética , Animales , Proteínas Cromosómicas no Histona/fisiología , Proteínas de Unión al ADN/fisiología , Modelos Animales de Enfermedad , Humanos , Neurilemoma/patología , Neurilemoma/terapia , Neurofibromatosis/patología , Neurofibromatosis/terapia , Proteína SMARCB1 , Neoplasias Cutáneas/patología , Neoplasias Cutáneas/terapia , Factores de Transcripción/fisiología , Carga TumoralRESUMEN
Schwannomatosis is a rare hereditary cancer syndrome in which patients develop multiple non-vestibular schwannomas. The chromatin remodelling gene SMARCB1 (also known as INI1, hSNF5, and BAF47) has been identified as a schwannomatosis predisposing gene, being involved in a subset of sporadic and familial cases. Recent studies have shown that SMARCB1 may also be involved in the development of multiple meningiomas. Previously, we demonstrated that the SMARCB1 exon 2 missense mutation c.143 C > T segregates with the presence of meningiomas in five members of a large family with multiple meningiomas and schwannomas. We extended our genetic analyses by screening 44 additional at-risk family members and identified 13 new carriers. Eleven of these were subjected to magnetic resonance imaging (MRI) of brain and spine. In addition, we analyzed four meningiomas and two schwannomas from family members for the presence of schwannomatosis-specific changes. We found in each tumor retention of the SMARCB1 exon 2 mutation, acquisition of an independent neurofibromatosis type 2 (NF2) gene mutation, and loss of heterozygosity at SMARCB1 and NF2 by loss of the wild-type copy of both genes. The MRI scans revealed one or more falx meningiomas in seven of 11 (64%) newly identified SMARCB1 mutation carriers. We conclude that the SMARCB1 exon 2 missense mutation in this family predisposes to the development of meningiomas as well as schwannomas, occurring via the same genetic pathways, and that this mutation preferentially induces cranial meningiomas located at the falx cerebri.
Asunto(s)
Proteínas Cromosómicas no Histona/genética , Proteínas de Unión al ADN/genética , Duramadre/patología , Predisposición Genética a la Enfermedad , Mutación de Línea Germinal , Neoplasias Meníngeas/genética , Meningioma/genética , Neurilemoma/genética , Factores de Transcripción/genética , Adulto , Anciano , Secuencia de Bases , Análisis Mutacional de ADN , Femenino , Pruebas Genéticas , Humanos , Masculino , Neoplasias Meníngeas/patología , Meningioma/patología , Repeticiones de Microsatélite , Persona de Mediana Edad , Datos de Secuencia Molecular , Mutación Missense , Neurilemoma/patología , Linaje , Proteína SMARCB1 , Adulto JovenRESUMEN
AIMS: Epithelioid sarcoma (ES) is a distinct sarcoma-type with a specific morphology and immunophenotype. Whereas focal myxoid change does occur, to our knowledge only two cases of ES with diffuse myxoid stroma have been reported previously. To characterize more clearly the myxoid variant of ES, we describe six additional cases and discuss the differential diagnoses. METHODS AND RESULTS: Cases were retrieved from the authors' files and studied histologically, immunohistochemically and by molecular methods. The age of the patients, four females and two males, ranged from 16 to 74 years (median: 33 years). The neoplasms arose in an extremity (two cases), the abdominal wall, groin, perineum and shoulder (one case each). Histologically, four cases were of the conventional type, and two were of the proximal type and the immunophenotype was typical for ES. The tumour stroma, however, revealed prominent myxoid changes, ranging from 50 to 90% (median: 75%). Only one of the proximal type ES showed a SMARCB1 mutation, whereas the other tumours showed no mutation. CONCLUSIONS: The myxoid variant of ES represents a diagnostic challenge and may be confused with other benign and malignant myxoid neoplasms. The main differential diagnosis is myoepithelioma of the skin and soft tissue.
Asunto(s)
Mioepitelioma/patología , Sarcoma/patología , Adolescente , Adulto , Anciano , Proteínas Cromosómicas no Histona/genética , Proteínas de Unión al ADN/genética , Femenino , Humanos , Masculino , Persona de Mediana Edad , Mioepitelioma/diagnóstico , Mioepitelioma/genética , Proteína SMARCB1 , Sarcoma/diagnóstico , Sarcoma/genética , Factores de Transcripción/genéticaRESUMEN
PURPOSE: To investigate the radiosensitizing potential of temozolomide (TMZ) for human glioblastoma multiforme (GBM) cell lines using single-dose and fractionated gamma-irradiation. METHODS AND MATERIALS: Three genetically characterized human GBM cell lines (AMC-3046, VU-109, and VU-122) were exposed to various single (0-6 Gy) and daily fractionated doses (2 Gy per fraction) of gamma-irradiation. Repeated TMZ doses were given before and concurrent with irradiation treatment. Immediately plated clonogenic cell-survival curves were determined for both the single-dose and the fractionated irradiation experiments. To establish the net effect of clonogenic cell survival and cell proliferation, growth curves were determined, expressed as the number of surviving cells. RESULTS: All three cell lines showed MGMT promoter methylation, lacked MGMT protein expression, and were sensitive to TMZ. The isotoxic TMZ concentrations used were in a clinically feasible range of 10 micromol/L (AMC-3046), 3 micromol/L (VU-109), and 2.5 micromol/L (VU-122). Temozolomide was able to radiosensitize two cell lines (AMC 3046 and VU-122) using single-dose irradiation. A reduction in the number of surviving cells after treatment with the combination of TMZ and fractionated irradiation was seen in all three cell lines, but only AMC 3046 showed a radiosensitizing effect. CONCLUSIONS: This study on TMZ-sensitive GBM cell lines shows that TMZ can act as a radiosensitizer and is at least additive to gamma-irradiation. Enhancement of the radiation response by TMZ seems to be independent of the epigenetically silenced MGMT gene.
Asunto(s)
Neoplasias Encefálicas/radioterapia , Dacarbazina/análogos & derivados , Glioblastoma/radioterapia , Proteínas de Neoplasias/metabolismo , O(6)-Metilguanina-ADN Metiltransferasa/metabolismo , Tolerancia a Radiación/efectos de los fármacos , Fármacos Sensibilizantes a Radiaciones/uso terapéutico , Neoplasias Encefálicas/enzimología , Neoplasias Encefálicas/genética , Línea Celular Tumoral , Proliferación Celular/efectos de los fármacos , Proliferación Celular/efectos de la radiación , Supervivencia Celular/efectos de los fármacos , Supervivencia Celular/efectos de la radiación , Terapia Combinada/métodos , Metilación de ADN , Dacarbazina/uso terapéutico , Fraccionamiento de la Dosis de Radiación , Genes Supresores de Tumor , Glioblastoma/enzimología , Glioblastoma/genética , Humanos , Temozolomida , Ensayos Antitumor por Modelo de Xenoinjerto/métodosRESUMEN
OBJECT: In nearly all patients with glioblastoma multiforme (GBM) a local recurrence develops within a short period of time. In this paper the authors describe two patients in whom a second GBM developed after a relatively long time interval at a site remote from the primary tumor. The genetic profiles of the tumors were compared to discriminate between distant recurrence and a second primary tumor. METHODS: Both patients harboring a supratentorial GBM were treated with surgery and local high-dose radiotherapy. Local control of the disease at the primary tumor site was achieved. Within 2 years, a second GBM developed in both patients, not only outside the previously irradiated target areas but infratentorially in one patient and in the opposite hemisphere in the other. The tumors were examined for the presence of several genetic alterations that are frequently found in GBMs--a loss of heterozygosity at chromosome regions 1p36, 10pl5, 19q13, and 22q13, and at the CDKN2A, PTEN, DMBT1, and TP53 gene regions; a TP53 mutation; and EGFR amplification. In the first patient, genetic profiling revealed that the primary tumor had an allelic imbalance for markers in several chromosome regions for which the second tumor displayed a complete loss. In the second patient, genetic profiling demonstrated the presence of genetic changes in the second tumor that were identical with and additional to those found in the primary tumor. CONCLUSIONS: Based on the similarities between the genetic profiles of the primary and the second tumors in these patients, the authors decided that in each case the second distant GBM was a distant recurrence rather than a second independent primary tumor.
Asunto(s)
Lóbulo Frontal , Glioblastoma/genética , Glioblastoma/secundario , Neoplasias Infratentoriales/genética , Neoplasias Supratentoriales/genética , Neoplasias Supratentoriales/patología , Adulto , Diagnóstico Diferencial , Glioblastoma/terapia , Humanos , Neoplasias Infratentoriales/secundario , Masculino , Persona de Mediana Edad , Neoplasias Primarias Secundarias/diagnóstico , Neoplasias Primarias Secundarias/genética , Neoplasias Supratentoriales/terapia , Factores de TiempoRESUMEN
The peripheral myelin protein (PMP22) gene is highly expressed in peripheral Schwann cells and encodes an important constituent of the myelin sheath. It is also expressed at lower levels in other normal tissues in which the protein is supposed to be involved in cell growth regulation. We recently reported frequent amplification and overexpression of PMP22 in high-grade osteosarcoma. Here, we analyzed PMP22 expression in five osteosarcoma tumors and three osteosarcoma cell lines. In normal Schwann cells, transcription of PMP22 starts at three promoters, P1A, P1B, and P2, which results in the synthesis of three alternatively spliced transcripts that all code for the same protein. We found a comparable expression pattern in normal osteoblasts. However, promoter P1A-driven transcripts were absent in all investigated tumors and cell lines and, compared to normal osteoblasts, the P1B/P2 transcript ratio was found to be increased in two of three cases with PMP22 overexpression and decreased in all five cases without overexpression. In normal Schwann cells and in NIH3T3 cells, PMP22 expression increases upon serum starvation-induced growth arrest. In contrast to this, serum withdrawal caused a considerable decrease of PMP22 expression in the osteosarcoma cell lines. We conclude that the different PMP22 expression in osteosarcoma may result in alternative availability of the PMP22 protein during the cell cycle and aberrant regulation of cell growth control in osteosarcoma tumorigenesis.
Asunto(s)
Neoplasias Óseas/genética , Regulación Neoplásica de la Expresión Génica/genética , Proteínas de la Mielina/genética , Osteosarcoma/genética , Empalme Alternativo , Animales , Apoptosis , Ciclo Celular , Humanos , Ratones , Células 3T3 NIH/citología , Células 3T3 NIH/metabolismo , Osteoblastos/citología , Osteoblastos/metabolismo , Regiones Promotoras Genéticas , ARN Mensajero/genética , Células de Schwann/citología , Células de Schwann/metabolismo , Suero/metabolismo , Inanición , Transcripción Genética , Células Tumorales CultivadasRESUMEN
We summarize and briefly discuss recent findings with respect to the amplification and overexpression of candidate oncogenes in 17p11.2 ~p12 in high-grade osteosarcomas. Amplification of this region occurs in about 25% of cases. The amplification profiles are often complex and suggest the involvement of more than one oncogene. The 17p11.2 ~ p12 region harbors many low-copy repeats (LCRs). We propose LCR-mediated repeated duplication by mitotic nonallelic homologous recombination as mechanism for the generation of the amplifications in this region. Genes PMP22 and COPS3 and three expressed sequence tags from within 17p11.2 ~ p12 have been found to be frequently overexpressed and consistently overexpressed after amplification, which identifies them as candidate oncogenes in this region. Overexpression of COPS3 has been linked to TP53 protein degradation and, being equivalent to TP53 mutation, the induction of genomic instability, which frequently occurs in high-grade osteosarcoma. These findings may serve as a framework for future work aimed to identify the causative oncogenes in 17p11.2 ~p12, to clarify the mechanism of their amplification, and to determine their importance in osteosarcoma tumorigenesis.
Asunto(s)
Neoplasias Óseas/genética , Cromosomas Humanos Par 17/genética , Regulación Neoplásica de la Expresión Génica , Osteosarcoma/genética , Complejo del Señalosoma COP9 , Transformación Celular Neoplásica/genética , ADN de Neoplasias/genética , Etiquetas de Secuencia Expresada , Amplificación de Genes , Perfilación de la Expresión Génica , Humanos , Modelos Genéticos , Proteínas de la Mielina/genética , Proteínas de Neoplasias/genética , Proteínas de Neoplasias/metabolismo , Hibridación de Ácido Nucleico , Oncogenes , Proteínas Proto-Oncogénicas/genética , Proteína p53 Supresora de Tumor/metabolismoRESUMEN
We reported previously the amplification of DNA markers in 17p12 in 3 of 60 high-grade gliomas. To detect additional cases, we screened in total 104 gliomas of various types and grades by Southern blot analysis using marker 745R, which is within the commonly amplified region. However, no other caseswith significant amplification (amplification level > 4) were found. To investigate in detail the extent of the amplifications in the three tumors, which were all glioblastomas, we determined 17p11.2 approximately p12 amplification profiles by semiquantitative polymerase chain reaction using 15 microsatellite markers and seven candidate genes. Distinct and high-level amplifications, with maximum levels ranging from 15 to 38, were found in these tumors. The 0.8 Mb-region between D17S1525 and MAP2K4 in 17p12 proved to be commonly amplified in these tumors. In one tumor, a heterogeneous distribution of the amplification in 17p12 was found, suggesting that it is a late event during glioma tumorigenesis. Another tumor showed additional high-level amplification of PMP22 and D17S1843 in 17p11.2. From the high-level amplifications we conclude that at least one, but possibly more, putative oncogenes are present in 17p11.2 approximately p12 whose amplifications and/or overexpressions contribute to glioma tumorigenesis.
Asunto(s)
Cromosomas Humanos Par 17/genética , Amplificación de Genes , Glioma/genética , Southern Blotting , Neoplasias Óseas/genética , Transformación Celular Neoplásica/genética , Aberraciones Cromosómicas , Cromosomas Humanos Par 17/ultraestructura , ADN de Neoplasias/genética , Humanos , Repeticiones de Microsatélite , Osteosarcoma/genética , Reacción en Cadena de la PolimerasaRESUMEN
Osteosarcomas are malignant tumors of the bone that are characterized by complex genetic changes, including loss and amplification of chromosome regions. Region 17p11.2 approximately p12 is frequently found to be amplified in this tumor, suggesting the presence of an oncogene (or oncogenes) important in osteosarcoma tumorigenesis. We had previously determined amplification profiles for this region. Reasoning that amplification of a causative oncogene in a tumor should result in increased expression of that gene, we have now determined the expression status of genes and expressed sequence tags (ESTs) in 17p11.2 approximately p12. We constructed a 17p11.2 approximately p12-specific macroarray containing 40 genes and 21 ESTs from this region, which was used for expression profiling of 11 osteosarcoma samples (9 tumors and 2 cell lines) and of normal human osteoblasts. Compared to normal osteoblasts, genes with at least threefold increased expression were considered to be overexpressed in the tumor. Genes PMP22 and COPS3, EST AA126939 (encoding part of the hypothetical protein FLJ20343), and two anonymous ESTs (AA918483 and R02360) were found to be most consistently overexpressed after amplification. By real-time reverse transcriptase polymerase chain reaction, we could confirm the overexpression status of PMP22 and COPS3 but not of FLJ20343. We conclude that PMP22 and COPS3, and possibly also the three ESTs, are candidate amplification targets in 17p11.2 approximately p12 in osteosarcoma.
Asunto(s)
Neoplasias Óseas/genética , Cromosomas Humanos Par 17/genética , Amplificación de Genes , Osteoblastos/metabolismo , Osteosarcoma/genética , Adulto , Neoplasias Óseas/patología , Complejo del Señalosoma COP9 , Mapeo Cromosómico , Humanos , Proteínas de la Membrana/genética , Microcuerpos , Osteosarcoma/patología , Proteínas Proto-Oncogénicas/genéticaRESUMEN
Amplification of region 17p11.2 approximately p12 has been found in 13%-29% of high-grade osteosarcomas, suggesting the presence of an oncogene or oncogenes that may contribute to their development. To determine the location of these putative oncogenes, we established 17p11.2 approximately p12 amplification profiles by semiquantitative PCR, using 15 microsatellite markers and seven candidate genes in 19 high-grade osteosarcomas. Most of the tumors displayed complex amplification profiles, with frequent involvement of marker D17S2041 in 17p12 and TOP3A in 17p11.2 and, in some cases, very high-level amplification of PMP22 and MAPK7 in 17p11.2. Our findings suggest that multiple amplification targets, including PMP22, TOP3A, and MAPK7 or genes close to these candidate oncogenes, may be present in 17p11.2 approximately p12 and thus contribute to osteosarcoma tumorigenesis.
Asunto(s)
Neoplasias Óseas/genética , Cromosomas Humanos Par 17/ultraestructura , ADN-Topoisomerasas de Tipo I/genética , Amplificación de Genes , Proteínas de la Membrana/genética , Proteínas Quinasas Activadas por Mitógenos/genética , Oncogenes , Osteosarcoma/genética , Neoplasias Óseas/patología , Mapeo Cromosómico , Cromosomas Humanos Par 17/genética , ADN de Neoplasias/genética , Marcadores Genéticos , Humanos , Repeticiones de Microsatélite , Proteína Quinasa 7 Activada por Mitógenos , Osteosarcoma/patología , Reacción en Cadena de la PolimerasaRESUMEN
Germline SMARCB1 mutations predispose in schwannomatosis patients to the development of multiple benign schwannomas and, in some cases, meningiomas. Here, we report on a 34-year-old female patient who developed multiple schwannomas at various locations and in addition a leiomyoma of the cervix uteri. She carried a c.362+1G>A mutation that inactivates the donor splice site of exon 3. This mutation caused the schwannomatosis phenotype in this patient and was also demonstrated to be present in her affected mother. The leiomyoma displayed the genetic features that are characteristic for germline SMARCB1 mutation-associated tumors. The mutant allele retained in the tumor, whereas the wild-type allele was lost by loss of heterozygosity. Furthermore, the loss of heterozygosity involved net loss of chromosome 22. An NF2 mutation was not found. However, quantitative polymerase chain reaction suggested that both NF2 copies were lost in the tumor. Immunostaining with a SMARCB1 antibody revealed the mosaic expression pattern that is typical for schwannomatosis-associated tumors. To our knowledge, this is the first reported case of leiomyoma associated with a germline SMARCB1 mutation. As such, it widens the spectrum of benign tumors associated with a germline SMARCB1 mutation.
Asunto(s)
Proteínas Cromosómicas no Histona/genética , Proteínas de Unión al ADN/genética , Mutación de Línea Germinal , Leiomioma/genética , Neurilemoma/genética , Neurofibromatosis/genética , Neoplasias Cutáneas/genética , Factores de Transcripción/genética , Neoplasias del Cuello Uterino/genética , Adulto , Proteínas Cromosómicas no Histona/análisis , Análisis Mutacional de ADN , Proteínas de Unión al ADN/análisis , Femenino , Genes de la Neurofibromatosis 2 , Predisposición Genética a la Enfermedad , Herencia , Humanos , Inmunohistoquímica , Leiomioma/química , Pérdida de Heterocigocidad , Neurilemoma/química , Linaje , Fenotipo , Proteína SMARCB1 , Neoplasias Cutáneas/química , Factores de Transcripción/análisis , Neoplasias del Cuello Uterino/químicaRESUMEN
Osteosarcoma is an aggressive bone tumor that preferentially develops in adolescents. The tumor is characterized by an abundance of genomic aberrations, which hampers the identification of the driver genes involved in osteosarcoma tumorigenesis. Our study aims to identify these genes by the investigation of focal copy number aberrations (CNAs, <3 Mb). For this purpose, we subjected 26 primary tumors of osteosarcoma patients to high-resolution single nucleotide polymorphism array analyses and identified 139 somatic focal CNAs. Of these, 72 had at least one gene located within or overlapping the focal CNA, with a total of 94 genes. For 84 of these genes, the expression status in 31 osteosarcoma samples was determined by expression microarray analysis. This enabled us to identify the genes of which the over- or underexpression was in more than 35% of cases in accordance to their copy number status (gain or loss). These candidate genes were subsequently validated in an independent set and furthermore corroborated as driver genes by verifying their role in other tumor types. We identified CMTM8 as a new candidate tumor suppressor gene and GPR177 as a new candidate oncogene in osteosarcoma. In osteosarcoma, CMTM8 has been shown to suppress EGFR signaling. In other tumor types, CMTM8 is known to suppress the activity of the oncogenic protein c-Met and GPR177 is known as an overexpressed upstream regulator of the Wnt-pathway. Further studies are needed to determine whether these proteins also exert the latter functions in osteosarcoma tumorigenesis.
Asunto(s)
Neoplasias Óseas/genética , Quimiocinas/genética , Variaciones en el Número de Copia de ADN/genética , Péptidos y Proteínas de Señalización Intracelular/genética , Proteínas con Dominio MARVEL/genética , Osteosarcoma/genética , Receptores Acoplados a Proteínas G/genética , Adolescente , Adulto , Transformación Celular Neoplásica/genética , Niño , Aberraciones Cromosómicas , Hibridación Genómica Comparativa , Femenino , Dosificación de Gen/genética , Perfilación de la Expresión Génica , Regulación Neoplásica de la Expresión Génica , Humanos , Masculino , Persona de Mediana Edad , Análisis de Secuencia por Matrices de Oligonucleótidos , Oncogenes/genética , Polimorfismo de Nucleótido Simple , Proteínas Proto-Oncogénicas c-met/antagonistas & inhibidores , Proteínas Supresoras de Tumor/genética , Vía de Señalización Wnt/genética , Adulto JovenRESUMEN
BACKGROUND: Genetic and epigenetic profiling of glioblastomas has provided a comprehensive list of altered cancer genes of which only O(6)-methylguanine-methyltransferase (MGMT) methylation is used thus far as a predictive marker in a clinical setting. We investigated the prognostic significance of genetic and epigenetic alterations in glioblastoma patients. METHODS: We screened 98 human glioblastoma samples for genetic and epigenetic alterations in 10 genes and chromosomal loci by PCR and multiplex ligation-dependent probe amplification (MLPA). We tested the association between these genetic and epigenetic alterations and glioblastoma patient survival. Subsequently, we developed a 2-gene survival predictor. RESULTS: Multivariate analyses revealed that mutations in isocitrate dehydrogenase 1 (IDH1), promoter methylation of MGMT, irradiation dosage, and Karnofsky Performance Status (KFS) were independent prognostic factors. A 2-gene predictor for glioblastoma survival was generated. Based on the genetic and epigenetic status of IDH1 and MGMT, glioblastoma patients were stratified into 3 clinically different genotypes: glioblastoma patients with IDH1mt/MGMTmet had the longest survival, followed by patients with IDH1mt/MGMTunmet or IDH1wt/MGMTmet, and patients with IDH1wt/MGMTunmet had the shortest survival. This 2-gene predictor was an independent prognostic factor and performed significantly better in predicting survival than either IDH1 mutations or MGMT methylation alone. The predictor was validated in 3 external datasets. DISCUSSION: The combination of IDH1 mutations and MGMT methylation outperforms either IDH1 mutations or MGMT methylation alone in predicting survival of glioblastoma patients. This information will help to increase our understanding of glioblastoma biology, and it may be helpful for baseline comparisons in future clinical trials.
Asunto(s)
Neoplasias Encefálicas/genética , Neoplasias Encefálicas/mortalidad , Metilasas de Modificación del ADN/genética , Enzimas Reparadoras del ADN/genética , Glioblastoma/genética , Glioblastoma/mortalidad , Isocitrato Deshidrogenasa/genética , Mutación , Proteínas Supresoras de Tumor/genética , Adulto , Anciano , Anciano de 80 o más Años , Metilación de ADN , Epigénesis Genética , Femenino , Humanos , Masculino , Persona de Mediana Edad , Análisis de SupervivenciaRESUMEN
Osteosarcoma is the most common primary malignancy of bone. The tumours are characterized by high genomic instability, including the occurrence of multiple regions of amplifications and deletions. Chromosome region 17p11.2-p12 is amplified in about 25% of cases. In previous studies, COPS3 and PMP22 have been identified as candidate oncogenes in this region. Considering the complexity and variation of the amplification profiles for this segment, the involvement of additional causative oncogenes is to be expected. The aim of the present investigation is to identify novel candidate oncogenes in 17p11.2-p12. We selected 26 of in total 85 osteosarcoma samples (31%) with amplification events in 17p11.2-p12, using quantitative PCR for 8 marker genes. These were subjected to high-resolution SNP array analysis and subsequent GISTIC analysis to identify the most significantly amplified regions. Two major amplification peaks were found in the 17p11.2-p12 region. Overexpression as a consequence of gene amplification is a major mechanism for oncogene activation in tumours. Therefore, to identify the causative oncogenes, we next determined expression levels of all genes within the two segments using expression array data that could be generated for 20 of the selected samples. We identified 11 genes that were overexpressed through amplification in at least 50% of cases. Nine of these, c17orf39, RICH2, c17orf45, TOP3A, COPS3, SHMT1, PRPSAP2, PMP22, and RASD1, demonstrated a significant association between copy number and expression level. We conclude that these genes, including COPS3 and PMP22, are candidate oncogenes in 17p11.2-p12 of importance in osteosarcoma tumourigenesis.
Asunto(s)
Neoplasias Óseas/genética , Cromosomas Humanos Par 17/genética , Clonación Molecular , Oncogenes/genética , Osteosarcoma/genética , Adolescente , Adulto , Anciano , Neoplasias Óseas/patología , Niño , Clonación Molecular/métodos , Estudios de Cohortes , Femenino , Estudios de Asociación Genética , Humanos , Masculino , Persona de Mediana Edad , Análisis de Secuencia por Matrices de Oligonucleótidos , Osteosarcoma/patología , Células Tumorales Cultivadas , Adulto JovenRESUMEN
Patients with schwannomatosis develop multiple schwannomas but no vestibular schwannomas diagnostic of neurofibromatosis type 2. We report an inactivating germline mutation in exon 1 of the tumor-suppressor gene INI1 in a father and daughter who both had schwannomatosis. Inactivation of the wild-type INI1 allele, by a second mutation in exon 5 or by clear loss, was found in two of four investigated schwannomas from these patients. All four schwannomas displayed complete loss of nuclear INI1 protein expression in part of the cells. Although the exact oncogenetic mechanism in these schwannomas remains to be elucidated, our findings suggest that INI1 is the predisposing gene in familial schwannomatosis.
Asunto(s)
Proteínas Cromosómicas no Histona/genética , Proteínas de Unión al ADN/genética , Predisposición Genética a la Enfermedad , Mutación de Línea Germinal/genética , Neurilemoma/genética , Factores de Transcripción/genética , Adulto , Secuencia de Bases , Proteínas Cromosómicas no Histona/metabolismo , Cartilla de ADN , Proteínas de Unión al ADN/metabolismo , Exones/genética , Femenino , Humanos , Inmunohistoquímica , Masculino , Datos de Secuencia Molecular , Neurilemoma/patología , Proteína SMARCB1 , Análisis de Secuencia de ADN , Factores de Transcripción/metabolismoRESUMEN
Ependymomas frequently display allelic loss of chromosome 22 in the absence of mutations in the known tumor-suppressor genes on chromosome 22, suggesting the role of an alternative predisposing gene or genes from this chromosome. In an effort to localize these genes, 37 ependymomas derived from 33 patients were analyzed for the presence of copy number changes by use of a high-resolution chromosome 22 genomic microarray. Eighteen ependymomas (49%) displayed an array-CGH profile consistent with monosomy of chromosome 22. However, in 10 of these tumors, the fluorescence ratios for 22q clones scored as deleted were different from those at the single gene copy level. This suggests either analysis of mixed populations of tumor and normal stromal cells or analysis of mixed tumor cell populations with different genetic profiles. Four ependymomas derived from two patients showed overlapping interstitial deletions of 2.2 Mb and approximately 510 kb. Further analyses revealed that these deletions were present in the constitutional DNA of these two patients as well as in some of their unaffected relatives. Detailed microsatellite analysis of these families refined the commonly deleted segment to a region of 320 kb between markers RH13801 and D22S419. Our results provide additional evidence for the involvement of genes on chromosome 22 in the development of ependymoma and suggest the presence of a low-penetrance ependymoma susceptibility locus at 22q11.