RESUMEN
Acute lymphoblastic leukemia (ALL), the most common malignant disorder in childhood, is typically associated with numerical chromosomal aberrations, fusion genes or small focal deletions, thought to represent important pathogenetic events in the development of the leukemia. Mutations, such as single nucleotide changes, have also been reported in childhood ALL, but these have only been studied by sequencing a small number of candidate genes. Herein, we report the first unbiased sequencing of the whole exome of two cases of pediatric ALL carrying the ETV6/RUNX1 (TEL/AML1) fusion gene (the most common genetic subtype) and corresponding normal samples. A total of 14 somatic mutations were identified, including four and seven protein-altering nucleotide substitutions in each ALL. Twelve mutations (86%) occurred in genes previously described to be mutated in other types of cancer, but none was found to be recurrent in an extended series of 29 ETV6/RUNX1-positive ALLs. The number of single nucleotide mutations was similar to the number of copy number alterations as detected by single nucleotide polymorphism arrays. Although the true pathogenetic significance of the mutations must await future functional evaluations, this study provides a first estimate of the mutational burden at the genetic level of t(12;21)-positive childhood ALL.
Asunto(s)
Aberraciones Cromosómicas , Exoma/genética , Mutación/genética , Proteínas de Fusión Oncogénica/genética , Polimorfismo de Nucleótido Simple/genética , Leucemia-Linfoma Linfoblástico de Células Precursoras/genética , Estudios de Casos y Controles , Niño , Subunidad alfa 2 del Factor de Unión al Sitio Principal , Dosificación de Gen , Fusión Génica , Humanos , Pronóstico , Análisis de Secuencia de ADNRESUMEN
Cancer is, at the cellular level, a genetic disease and acquired gene fusions play a causal role in the initiation of the neoplastic process either by activating proto-oncogenes or creating hybrid genes. We constructed a network by combining the 5' and 3' parts of all presently known gene fusions in human neoplasia and here we show that the observed network is fragmented and that the organization of the genes demonstrates a scale-free network topology with a power law degree distribution meeting the requirements of P(k) approximately k(-gamma), that is, conforming to the distributions found in naturally occurring networks such as the Internet and social or ecological networks. The results hence indicate that the complex system of pairwise interacting genes leading to neoplasia is governed by a universal principle.
Asunto(s)
Algoritmos , Regulación de la Expresión Génica/genética , Fusión Génica , Neoplasias/genética , Simulación por Computador , Duplicación de Gen , HumanosRESUMEN
Although many of the chromosomal abnormalities in hematologic malignancies are identifiable cytogenetically, some are only detectable using molecular methods. We describe a novel cryptic t(7;21)(p22;q22) in acute myeloid leukemia (AML). FISH, 3'RACE, and RT-PCR revealed a fusion involving RUNX1 and the ubiquitin-specific protease (USP) gene USP42. The genomic breakpoint was in intron 7 of RUNX1 and intron 1 of USP42. The reciprocal chimera was not detected - neither on the transcriptional nor on the genomic level - and FISH showed that the 5' part of USP42 was deleted. USP42 maps to a 7p22 region characterized by segmental duplications. Notably, 17 kb duplicons are present 1 Mb proximal to USP42 and 3 Mb proximal to RUNX1; these may be important in the genesis of t(7;21). This is the second cryptic RUNX1 translocation in hematologic malignancies and the first in AML. The USPs have not previously been reported to be rearranged in leukemias. The cellular context in which USP42 is active is unknown, but we here show that it is expressed in normal bone marrow, in primary AMLs, and in cancer cell lines. Its involvement in the t(7;21) suggests that deregulation of ubiquitin-associated pathways may be pathogenetically important in AML.
Asunto(s)
Cromosomas Humanos Par 21/genética , Cromosomas Humanos Par 7/genética , Subunidad alfa 2 del Factor de Unión al Sitio Principal/genética , Endopeptidasas/genética , Leucemia Mieloide/genética , Proteínas de Fusión Oncogénica/genética , Translocación Genética , Enfermedad Aguda , Línea Celular Tumoral , Niño , Análisis Citogenético/métodos , Perfilación de la Expresión Génica , Reordenamiento Génico , Humanos , Hibridación Fluorescente in Situ/métodos , Masculino , ARN Mensajero/genética , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa/métodos , Tioléster Hidrolasas , Transcripción Genética , Proteasas Ubiquitina-EspecíficasRESUMEN
Hematologic malignancies are characterized by fusion genes of biological/clinical importance. Immortalized cell lines with such aberrations are today widely used to model different aspects of leukemogenesis. Using cDNA microarrays, we determined the gene expression profiles of 40 cell lines as well as of primary leukemias harboring 11q23/MLL rearrangements, t(1;19)[TCF3/PBX1], t(12;21)[ETV6/RUNX1], t(8;21)[RUNX1/CBFA2T1], t(8;14)[IGH@/MYC], t(8;14)[TRA@/MYC], t(9;22)[BCR/ABL1], t(10;11)[PICALM/MLLT10], t(15;17)[PML/RARA], or inv(16)[CBFB/MYH11]. Unsupervised classification revealed that hematopoietic cell lines of diverse origin, but with the same primary genetic changes, segregated together, suggesting that pathogenetically important regulatory networks remain conserved despite numerous passages. Moreover, primary leukemias cosegregated with cell lines carrying identical genetic rearrangements, further supporting that critical regulatory pathways remain intact in hematopoietic cell lines. Transcriptional signatures correlating with clinical subtypes/primary genetic changes were identified and annotated based on their biological/molecular properties and chromosomal localization. Furthermore, the expression profile of tyrosine kinase-encoding genes was investigated, identifying several differentially expressed members, segregating with primary genetic changes, which may be targeted with tyrosine kinase inhibitors. The identified conserved signatures are likely to reflect regulatory networks of importance for the transforming abilities of the primary genetic changes and offer important pathogenetic insights as well as a number of targets for future rational drug design.
Asunto(s)
Perfilación de la Expresión Génica , Regulación Leucémica de la Expresión Génica , Leucemia/genética , Análisis de Secuencia por Matrices de Oligonucleótidos , Enfermedad Aguda , Linfoma de Burkitt/genética , Línea Celular Tumoral , Niño , Preescolar , Femenino , Humanos , Lactante , Leucemia Mielógena Crónica BCR-ABL Positiva/genética , Leucemia Mieloide/genética , Leucemia-Linfoma de Células T del Adulto/genética , Masculino , Leucemia-Linfoma Linfoblástico de Células Precursoras/genéticaRESUMEN
To ascertain the frequency of treatment-related acute myeloid leukemias and myelodysplastic syndromes (t-AML/t-MDS) in an unselected series, we have identified all adult cases analyzed in our department from 1976 to 1993. Further aims were to compare karyotypic features of t-AML/t-MDS with de novo AML/MDS, in our material as well as in 5098 unselected, cyto- genetically abnormal, published cases, and to analyze associations between type of prior therapy and karyotype. Among our 372 AML and 389 MDS, 47 (13%) were t-AML and 62 (16%) were t-MDS. Clonal abnormalities were significantly more common in t-AML and t-MDS than in de novo disease (68% vs 50%, P < 0.05 and 84% vs 45%, P < 0.001, respectively). Among the available 4230 AML and 1629 MDS (the present series and published cases), 14% were t-AML and 15% were t-MDS. In t-AML/t-MDS, the number of anomalies and the ploidy levels differed significantly from de novo cases, with complex and hypodiploid karyotypes being more common in t-AML/t-MDS. In t-AML, unbalanced changes in general, t(1;3), der(1;7), 3p-, -5, 5q-, -7, 7q-, t(9;11), t(11;19), t(11q23), der(12p), -17, der(17p), -18, and -21 were significantly more frequent than in de novo AML. In t-MDS, -5, -7, 7q-, 13q-, der(17p), and -18 were significantly more common. Type of prior treatment correlated significantly with number of anomalies in t-AML and with ploidy levels in t-AML/t-MDS. The frequencies of several aberrations varied with type of therapy, eg, 5q- was more frequent in radiotherapy-associated t-MDS, monosomy 7 was more common in t-AML and t-MDS after treatment with alkylators, and t(11q23) in t-AML was associated with topoisomerase II inhibitors. Abnormalities significantly more common in de novo disease were +8 as a sole anomaly, balanced changes in general, t(8;21), t(9;22), t(15;17), inv(16), and t(21q22) in AML, and -Y, 5q-, and 20q- as sole anomalies and +8 in MDS. The results emphasize the strong association between previous genotoxic exposure and karyotypic features.
Asunto(s)
Leucemia Mieloide/genética , Síndromes Mielodisplásicos/genética , Neoplasias Primarias Secundarias/genética , Enfermedad Aguda , Adulto , Anciano , Anciano de 80 o más Años , Antineoplásicos Alquilantes/efectos adversos , Aberraciones Cromosómicas , Inhibidores Enzimáticos/efectos adversos , Femenino , Humanos , Cariotipificación , Leucemia Mieloide/epidemiología , Leucemia Mieloide/mortalidad , Masculino , Persona de Mediana Edad , Síndromes Mielodisplásicos/epidemiología , Síndromes Mielodisplásicos/mortalidad , Neoplasias Primarias Secundarias/epidemiología , Neoplasias Primarias Secundarias/mortalidad , Radioterapia/efectos adversos , Estudios Retrospectivos , Tasa de Supervivencia , Inhibidores de Topoisomerasa IIRESUMEN
Acute myeloid leukemia (AML) with inv(16)(p13q22) or the variant t(16;16)(p13;q22), is strongly associated with the FAB subtype M4Eo. A high incidence of CNS involvement was reported in the 1980s, but otherwise little is known about the pattern of extamedullary leukemia (EML) manifestations in this AML type. We have compiled clinical and cytogenetic data on 27 consecutive AML cases with inv(16)/t(16;16) from southern Sweden. In general, these AMLs displayed the clinical features that have previously been described as characteristic for this disease entity: low median age, hyperleukocytosis, M4Eo morphology, and a favorable prognosis. However, CNS leukemia was only seen in relapse in one patient diagnosed in 1980, whereas the most common EML manifestation in our series was lymphadenopathy (5/27, 19%), most often cervical with or without gross tonsillar enlargement. A review of previously published, clinically informative cases corroborates that lymphadenopathy, with preference for the cervical region, is the most common EML at diagnosis in inv(16)-positive AML (58/175, 33%). CNS leukemia, on the other hand, has been reported in only 17% of the cases, mostly in the relapse setting, with a diminishing frequency over time, possibly due to protective effects of high-dose cytarabine. Other reported EML sites include the scalp, ovaries, and the intestine. Cervicotonsillar EML was in our series associated with a shorter duration of first remission, (P < 0.05), and may hence prove to be an important clinical parameter when deciding treatment strategies in AML with inv(16)/t(16;16).
Asunto(s)
Inversión Cromosómica , Cromosomas Humanos Par 16/genética , Leucemia Mielomonocítica Aguda/epidemiología , Infiltración Leucémica , Ganglios Linfáticos/patología , Tonsila Palatina/patología , Adulto , Anciano , Sistema Nervioso Central/patología , Niño , Preescolar , Cromosomas Humanos Par 16/ultraestructura , Femenino , Humanos , Leucemia Mielomonocítica Aguda/genética , Leucemia Mielomonocítica Aguda/patología , Masculino , Pronóstico , Estudios Retrospectivos , Resultado del TratamientoRESUMEN
Relatively little is known about the cytogenetic features of multiple myeloma (MM) when compared to other hematologic malignancies. The reasons for this are most likely manifold, and include a low mitotic index of the malignant cells and the presence of cytogenetically cryptic abnormalities as well as of complex karyotypes with poor chromosome morphology. In the present study, we have investigated whether various culture conditions may influence the yield of abnormal metaphases in MM and, in the related plasma cell dyscrasias, monoclonal gammopathy of undetermined significance (MGUS) and plasmacytomas (PC). In addition, the possible impact of age, gender, and disease phase on the cytogenetic features has been analyzed. A total of 95 samples from 74 cases (68 MM, three PC, and three MGUS patients) were obtained for cytogenetic analysis. The samples were cultured either in conventional medium or in medium containing IL-6 and GM-CSF, and the culture times varied from 24 to 120 h. In total, 186 cultures were analyzed. Metaphase fluorescence in situ hybridization analysis using probes specific for 14q32, i.e. IGH rearrangements, could be performed in 57 of the 74 cases, and revealed 14q32 aberrations in 10 cases not seen by conventional G-banding. Abnormal karyotypes were detected in 77 (41%) of the 186 cultures, 46 (48%) of the 95 samples, and in 41 (55%) of the 74 patients, revealing a total of 20 chromosomal aberrations previously not reported in plasma cell dyscrasias. We found no evidence that gender, age, disease phase, culture time, or cytokine stimulation significantly influences the karyotypic features of MM.
Asunto(s)
Médula Ósea/patología , Aberraciones Cromosómicas , Mapeo Cromosómico , Citocinas/fisiología , Mieloma Múltiple/genética , Mieloma Múltiple/inmunología , Adulto , Factores de Edad , Anciano , Anciano de 80 o más Años , Técnicas de Cultivo de Célula/métodos , Femenino , Reordenamiento Génico , Humanos , Cadenas Pesadas de Inmunoglobulina/genética , Cariotipificación , Masculino , Persona de Mediana Edad , Mieloma Múltiple/patología , Plasmacitoma/genética , Plasmacitoma/inmunología , Plasmacitoma/patología , Caracteres Sexuales , Células Tumorales CultivadasRESUMEN
The purpose of this study was to investigate the prognostic implications of BCL6 rearrangement in a uniformly treated population of patients with diffuse large B-cell lymphoma (DLBCL) and to characterise the relationship between BCL6 rearrangement and prognostic factors. A total of 269 patients with DLBCL entered a randomised trial comparing the chemotherapy regimen CHOP (cyclophosphamide, doxorubicin, vincristine, prednisone) to the MACOP-B (methotrexate, doxorubicin, cyclophosphamide, vincristine, prednisone, bleomycin) regimen. In 44 cases, frozen tissue was available for assessment of BCL6 status by Southern blot analysis. BCL6 was rearranged in six of 43 evaluable cases (14%), and was associated with elevated lactate dehydrogenase (LDH), and a higher patient age. No association between BCL6 status and expression of BCL2, Ki-67 or TP53 was found. Patients presenting with BCL6 rearrangement displayed a weak trend towards better overall and failure-free survival (67 and 67% at 5 years), compared to patients with germline BCL6 (63 and 52%), but the difference was not statistically significant. In accordance with previously published series, the presence of BCL6 rearrangement does not define a prognostically distinct subgroup of DLBCL. Assessment of BCL6 status may, however, be of clinical interest when related to other prognostic variables.
Asunto(s)
Proteínas de Unión al ADN/genética , Reordenamiento Génico de Linfocito B/genética , Linfoma de Células B/genética , Linfoma de Células B Grandes Difuso/genética , Proteínas Proto-Oncogénicas/genética , Factores de Transcripción/genética , Adolescente , Adulto , Anciano , Protocolos de Quimioterapia Combinada Antineoplásica/uso terapéutico , Bleomicina/uso terapéutico , Southern Blotting , Ciclofosfamida/uso terapéutico , ADN de Neoplasias/análisis , ADN de Neoplasias/metabolismo , Doxorrubicina/uso terapéutico , Humanos , Inmunofenotipificación , L-Lactato Deshidrogenasa/metabolismo , Leucovorina/uso terapéutico , Linfoma de Células B/tratamiento farmacológico , Linfoma de Células B Grandes Difuso/tratamiento farmacológico , Masculino , Metotrexato/uso terapéutico , Persona de Mediana Edad , Estadificación de Neoplasias , Prednisona/uso terapéutico , Pronóstico , Proteínas Proto-Oncogénicas c-bcl-6 , Vincristina/uso terapéuticoRESUMEN
Constitutive activation of tyrosine kinases as a consequence of chromosomal translocations, forming fusion genes, plays an important role in the development of hematologic malignancies, in particular, myeloproliferative syndromes (MPSs). In this respect, the t(9;22)(q34;q11) that results in the BCR/ABL fusion gene in chronic myeloid leukemia is one of the best-studied examples. The fibroblast growth factor receptor 1 (FGFR1) gene at 8p11 encodes a transmembrane receptor tyrosine kinase and is similarly activated by chromosomal translocations, in which three alternative genes-ZNF198 at 13q12, CEP110 at 9q34, and FOP at 6q27-become fused to the tyrosine kinase domain of FGFR1. These 8p11-translocations are associated with characteristic morphologic and clinical features, referred to as "8p11 MPS." In this study, we report the isolation and characterization of a novel fusion gene in a hematologic malignancy with a t(8;22)(p11;q11) and features suggestive of 8p11 MPS. We show that the breakpoints in the t(8;22) occur within introns 4 and 8 of the BCR and FGFR1 genes, respectively. On the mRNA level, the t(8;22) results in the fusion of BCR exons 1-4 in-frame with the tyrosine kinase domain of FGFR1 as well as in the expression of a reciprocal FGFR1/BCR chimeric transcript. By analogy with data obtained from previously characterized fusion genes involving FGFR1 and BCR/ABL, it is likely that the oligomerization domain contributed by BCR is critical and that its dimerizing properties lead to aberrant FGFR1 signaling and neoplastic transformation.
Asunto(s)
Cromosomas Humanos Par 22/genética , Cromosomas Humanos Par 8/genética , Genes abl/genética , Trastornos Mieloproliferativos/genética , Proteínas de Fusión Oncogénica/genética , Proteínas Oncogénicas/genética , Proteínas Tirosina Quinasas , Proteínas Proto-Oncogénicas , Proteínas Tirosina Quinasas Receptoras/genética , Receptores de Factores de Crecimiento de Fibroblastos/genética , Translocación Genética/genética , Anciano , Secuencia de Aminoácidos , Secuencia de Bases , Rotura Cromosómica/genética , Humanos , Masculino , Datos de Secuencia Molecular , Proteínas Proto-Oncogénicas c-bcr , Receptor Tipo 1 de Factor de Crecimiento de Fibroblastos , Transcripción GenéticaRESUMEN
The clinical course in urinary bladder cancer is difficult or impossible to predict based on conventional disease parameters. It is a reasonable hypothesis that the genetic aberrations acquired by the tumor cells, being instrumental in bringing about the disease in the first place, may also hold the key to more reliable prognostication. However, though 200 transitional cell carcinomas (TCC), the most common bladder cancer in the Western world, with clonal chromosomal abnormalities have been reported, our knowledge about the karyotypic characteristics of these tumors remains insufficient. The aberration pattern is clearly nonrandom, but no completely specific primary or secondary karyotypic abnormality has been identified, and the chronological order in which the aberrations appear during disease progression is not well known. The high degree of karyotypic complexity in epithelial tumors like TCC is one reason why our picture of the sequential order of cytogenetic evolution is unclear. To overcome some of these difficulties we have used several statistical methods that allow analysis and interpretation of the relationship between cytogenetic aberrations in TCC. We show that there exists a temporal order with respect to the appearance of chromosomal imbalances and that this order is highly correlated with tumor stage and grade. Analyzing changes in the distribution of imbalances per tumor in G1, G2, and G3 tumors, we suggest that progression involves the acquisition of cytogenetically detectable and submicroscopic genetic changes at comparable frequencies. By means of computer simulations, we show that the imbalances -9, +7, and 1q+ appear earlier than expected from random events and that -6q, -5q, -18, +5p, -22p, and -15 appear later than expected. Using principal component analysis, we identify two cytogenetic pathways in TCC, one initiated by -9 and followed by -11p and 1q+, the other initiated by +7 and followed by 8p- and +8q. The -9 pathway was correlated with stage Ta-T2 tumors, whereas the +7 pathway was correlated with stage T1-T3 tumors, i.e., +7 tumors appeared to be more aggressive. Although these pathways are well separated at earlier stages, they later converge to contain a common set of imbalances.
Asunto(s)
Carcinoma de Células Transicionales/genética , Aberraciones Cromosómicas , Neoplasias de la Vejiga Urinaria/genética , Carcinoma de Células Transicionales/patología , Humanos , Cariotipificación , Análisis Multivariante , Estadificación de Neoplasias , Neoplasias de la Vejiga Urinaria/patologíaRESUMEN
OBJECTIVES: To investigate a broad range of occupational, hobby, and lifestyle exposures, suggested as risk factors for Philadelphia chromosome positive (Ph+) chronic myeloid leukaemia (CML). METHODS: A case-control study, comprising 255 Ph+CML patients from southern Sweden and matched controls, was conducted. Individual data on work tasks, hobbies, and lifestyle exposures were obtained by telephone interviews. Occupational hygienists assessed occupational and hobby exposures for each subject individually. Also, occupational titles were obtained from national registries, and group level exposure-that is, the exposure proportion for each occupational title-was assessed with a job exposure matrix. The effects of 11 exposures using individual data and two exposures using group data (organic solvents and animal dust) were estimated. RESULTS: For the individual data on organic solvents, an effect was found for moderate or high intensity of exposure (odds ratio (OR) 3.4, 95% confidence interval (95% CI) 1.1 to 11) and for long duration (15-20 years) of exposure (OR 2.1, 95% CI 1.1 to 4.0). By contrast, the group data showed no association (OR 0.69, 95% CI 0.27 to 1.8; moderate or high intensity versus no exposure). For extremely low frequency electromagnetic fields (EMFs), only individual data were available. An association with long occupational exposure to EMFs was found (OR 2.3, 95% CI 1.2 to 4.5). However, no effect of EMF intensity was indicated. No significant effects of benzene, gasoline or diesel, or tobacco smoking were found. OR estimates below unity were suggested for personal use of hair dye and for agricultural exposures. CONCLUSIONS: Associations between exposure to organic solvents and EMFs, and Ph+CML were indicated but were not entirely consistent.
Asunto(s)
Pasatiempos , Leucemia Mielógena Crónica BCR-ABL Positiva/etiología , Estilo de Vida , Enfermedades Profesionales/etiología , Adulto , Anciano , Estudios de Casos y Controles , Campos Electromagnéticos/efectos adversos , Femenino , Humanos , Modelos Logísticos , Masculino , Persona de Mediana Edad , Exposición Profesional , Factores de Riesgo , Solventes/efectos adversosRESUMEN
Although trisomy 8 as a sole change is one of the most common chromosomal abnormalities in myeloid malignancies, it is largely unknown if the incidence of this aberration is influenced by other factors of clinical importance. In the present study, the frequencies of isolated +8 in relation to gender, age, previous treatment with chemo- or radiotherapy, and morphologic subtype were ascertained in published, as well as in our own unpublished, cases of acute myeloid leukemia (AML; n=4,246), myelodysplastic syndromes (MDS; n=1,817), and chronic myeloproliferative disorders (MPD; n=530). The frequencies of +8 were higher in MDS and MPD than in AML (7.5% vs. 5.6%; P<0.01) and varied among the morphologic subtypes of AML and MDS (P<0.001 and P<0.05, respectively). Trisomy 8 was more common in women than in men with MPD (11% vs. 5.1%; P<0.05). Furthermore, the frequencies of +8 were higher in de novo AML and MDS than in treatment-related cases (6.0% vs. 2.8%; P<0.01 and 8.6% vs. 1.5%; P<0.001, respectively). The incidence also varied significantly with age in AML (P<0.001), being more common in elderly patients. Although the causes for this frequency heterogeneity remain to be elucidated, possible explanations may include different environmental exposures affecting the origin of +8 in AML, MDS, and MPD and the presence of different underlying cryptic primary aberrations.
Asunto(s)
Aberraciones Cromosómicas , Cromosomas Humanos Par 8 , Leucemia Mieloide Aguda/genética , Síndromes Mielodisplásicos/genética , Trastornos Mieloproliferativos/genética , Trisomía , Factores de Edad , Femenino , Humanos , Masculino , Factores SexualesRESUMEN
Although mechanisms for chromosomal instability in tumors have been described in animal and in vitro models, little is known about these processes in man. To explore cytogenetic evolution in human tumors, chromosomal breakpoint profiles were constructed for 102 pancreatic carcinomas and 140 osteosarcomas, two tumor types characterized by extensive genomic instability. Cases with few chromosomal alterations showed a preferential clustering of breakpoints to the terminal bands, whereas tumors with many changes showed primarily interstitial and centromeric breakpoints. The terminal breakpoint frequency was negatively correlated to telomeric TTAGGG repeat length, and fluorescence in situ hybridization with telomeric TTAGGG probes consistently indicated shortened telomeres and >10% of chromosome ends lacking telomeric signals. Because telomeric dysfunction may lead to formation of unstable ring and dicentric chromosomes, mitotic figures were also evaluated. Anaphase bridges were found in all cases, and fluorescence in situ hybridization demonstrated extensive structural rearrangements of chromosomes, with terminal transferase detection showing fragmented DNA in 5-20% of interphase cells. Less than 2% of cells showed evidence of necrosis or apoptosis, and telomerase was expressed in the majority of cases. Telomeric dysfunction may thus trigger chromosomal fragmentation through persistent bridge-breakage events in pancreatic carcinomas and osteosarcomas, leading to a continuous reorganization of the tumor genome. Telomerase expression is not sufficient for completely stabilizing the chromosome complement but may be crucial for preventing complete genomic deterioration and maintaining cellular survival.
Asunto(s)
Aberraciones Cromosómicas , Fragmentación del ADN , Neoplasias/genética , Telómero , Adolescente , Adulto , Anciano , Anciano de 80 o más Años , Supervivencia Celular , Femenino , Humanos , Interfase , Masculino , Persona de Mediana Edad , Secuencias Repetitivas de Ácidos Nucleicos , Telomerasa/metabolismoRESUMEN
The MLL gene in chromosome band 11q23 is frequently rearranged in acute lymphoblastic and acute myeloid leukemias. To date, more than 50 different chromosomal regions are known to participate in translocations involving 11q23, many of which affect MLL. The pathogenetically important outcome of these rearrangements is most likely the creation of a fusion gene consisting of the 5' part of the MLL gene and the 3' end of the partner gene. Although abnormalities of the MLL gene as such are generally associated with poor survival, recent data suggest that the prognostic impact varies among the different fusion genes generated. Hence, detection of the specific chimeric gene produced is important for proper prognostication and clinical decision making. We have developed a paired multiplex reverse-transcriptase polymerase chain reaction analysis to facilitate a rapid and accurate detection of the most frequent MLL fusion genes in adult and childhood acute leukemias. To increase the specificity, two sets of primers were designed for each fusion gene, and these paired primer sets were run in parallel in two separate multiplex one-step PCR reactions. Using the described protocol, we were able to amplify successfully, in one single assay, the six clinically relevant fusion genes generated by the t(4;11)(q21;q23) [MLL/AF4], t(6;11)(q27;q23) [MLL/AF6], t(9;11)(p21-22;q23) [MLL/AF9], t(10;11)(p11-13;q23) [MLL/AF10], t(11;19)(q23;p13.1) [MLL/ELL], and t(11;19)(q23; p13.3) [MLL/ENL] in cell lines, as well as in patient material.
Asunto(s)
Proteínas de Unión al ADN/genética , Neoplasias Hematológicas/genética , Proteínas de Fusión Oncogénica/genética , Proto-Oncogenes , Factores de Transcripción , Biomarcadores de Tumor , Neoplasias Hematológicas/diagnóstico , N-Metiltransferasa de Histona-Lisina , Humanos , Proteína de la Leucemia Mieloide-Linfoide , Proteínas de Neoplasias/análisis , Proteínas de Neoplasias/genética , Proteínas de Fusión Oncogénica/análisis , Reacción en Cadena de la Polimerasa/métodos , Sensibilidad y EspecificidadRESUMEN
The prognostic impact of karyotypic patterns in a consecutive series of 389 adult myelodysplastic syndromes (MDS) was investigated. Time period did not significantly influence the survival times. In the analyses, the MDS cases were subdivided into the cytogenetic subgroups used in the International Prognostic Scoring System, i.e. favourable [-Y, del(5q) or del(20q) as single aberrations or normal karyotype, n = 241], poor [-7, del(7q), der(1;7) or complex karyotypes, i.e. > or = three abnormalities, n = 89] and intermediate (other aberrations, n = 59). The survival times correlated well with the prognostic subgroups, confirming that the cytogenetic classification was valid. Expressed as hazard ratios (HRs), with the favourable subgroup as the reference, the intermediate and poor subgroup HRs increased to 1.5 (95% confidence interval, 1.1-2.1) and 3.2 (2.4-4.1) respectively. Sex, age, morphological subtype and smoking habits significantly modified this prognostic impact. Shorter survival was detected for men in the favourable and the intermediate subgroups, but not in the poor prognosis subgroup. Using women in the favourable subgroup as the reference and adjusting for age, the HR for men was 1.6 (1.2-2.1) in the favourable subgroup. Adjusting for smoking habits as well decreased the HR to 1.4 (1.1-2.0) and, when also excluding cases with del(5q) as the sole anomaly, no significant difference could be discerned [HR 1.2 (0.9-1.6], suggesting that the better outcome for women in the favourable subgroup was mainly as a result of the '5q-syndrome' and to smoking habits. In the intermediate subgroup, the corresponding HRs were 3.0 (1.5-6.0) when adjusted for age and 2.7 (1.3-5.5) when also adjusted for smoking habits. Different survival times between men and women have never previously been reported for this MDS group. Although it remains to be elucidated whether environmental and/or constitutional factors cause the observed sex-related difference, these observations have obvious clinical ramifications, not least in designing and evaluating therapy protocols.
Asunto(s)
Síndromes Mielodisplásicos/genética , Factores Sexuales , Adulto , Factores de Edad , Anciano , Anciano de 80 o más Años , Femenino , Humanos , Cariotipificación , Masculino , Persona de Mediana Edad , Síndromes Mielodisplásicos/mortalidad , Pronóstico , Modelos de Riesgos Proporcionales , Fumar/efectos adversos , Tasa de SupervivenciaRESUMEN
A total of 3,016 malignant solid tumors (kidney, colorectal, breast, head and neck, ovarian, and lung carcinomas, neuroglial tumors, malignant melanoma, and testicular germ cell tumors) were selected for statistical analyses regarding karyotypic evolution. Genomic imbalances, i.e., net gains and losses, present in more than 5% of each tumor type were identified. Individual tumors were then classified with respect to absence or presence of these imbalances. To analyze for possible patterns of correlated imbalances, principal component analyses (PCA) were performed. Furthermore, algorithms were developed to analyze the temporal order of the imbalances, as well as the possible selection for early or late appearance in the karyotypic evolution. By analyzing the temporal order of imbalances common to many tumor types, a general order for nine of these emerged, namely, +7, -3p, -6q, -1p, -8p, -17p, -9p, -18, and -22. The distributions of the number of imbalances per case revealed a geometrical distribution, ranging from one to nine imbalances per tumor, in the majority of the tumor types. In tumor types in which cases with a high number of imbalances per case were frequent, notably head and neck, ovarian, and lung carcinomas, the overall distributions were bimodal, indicating the presence of two modes of chromosome evolution. By combining data from the PCA with the temporal analyses, it was possible to identify karyotypic pathways. It was found that the majority of the tumor types displayed more than one cytogenetic route, but, as the karyotypic evolution continued, these converged to a common pathway.
Asunto(s)
Desequilibrio Alélico , Evolución Molecular , Neoplasias/genética , Neoplasias de la Mama/genética , Carcinoma de Células Renales/genética , Carcinoma de Células Escamosas/genética , Aberraciones Cromosómicas/genética , Trastornos de los Cromosomas , Neoplasias Colorrectales/genética , Femenino , Neoplasias de Cabeza y Cuello/genética , Humanos , Cariotipificación , Neoplasias Renales/genética , Neoplasias Pulmonares/genética , Masculino , Melanoma/genética , Análisis Multivariante , Neoplasias Ováricas/genética , Neoplasias Testiculares/genéticaRESUMEN
Three adult de novo acute myeloid leukemias (AML M1, M2, and M4) with an isochromosome 7p are presented. No additional abnormalities were detected by G-band and multicolor, using combined binary ratio labeling, fluorescence in situ hybridization (FISH) analyses, indicating that the i(7p) was the sole, i.e., the primary, chromosomal aberration. Although the patients were elderly--68, 72, and 78 years old--they all responded very well to chemotherapy, achieving complete remission lasting more than a year. Further FISH analyses, using painting, centromeric, as well as 7q11.2-specific YAC probes, revealed that the i(7p) contained two centromeres and that the breakpoints were located in 7q11.2. Thus, the abnormality should formally be designated idic(7)(q11.2). The detailed mapping disclosed a breakpoint heterogeneity, with the breaks in 7q11.2 varying among the cases, being at least 1,310 kb apart. Furthermore, the breakpoints also differed within one of the cases, being located on both the proximal and the distal side of the most centromeric probe used. Based on our three patients, as well as on a previously reported 82-year-old patient with AML M2 and idic(7)(q11) as the only chromosomal change, we suggest that this abnormality, as the sole anomaly, is associated with AML in elderly patients who display a good response to induction chemotherapy and, hence, have a favorable prognosis. Furthermore, the heterogeneous breakpoints in 7q11.2 suggest that the important functional outcome of the idic(7)(q11.2) is the genomic imbalance incurred, i.e., gain of 7p and loss of 7q material, rather than a rearrangement of a specific gene.
Asunto(s)
Envejecimiento/genética , Cromosomas Humanos Par 7/genética , Isocromosomas/genética , Leucemia Mieloide Aguda/tratamiento farmacológico , Leucemia Mieloide Aguda/genética , Anciano , Anciano de 80 o más Años , Antimetabolitos Antineoplásicos/uso terapéutico , Protocolos de Quimioterapia Combinada Antineoplásica/uso terapéutico , Bandeo Cromosómico , Citarabina/uso terapéutico , Femenino , Humanos , Idarrubicina/uso terapéutico , Hibridación Fluorescente in Situ/métodos , Leucemia Mielomonocítica Aguda/tratamiento farmacológico , Leucemia Mielomonocítica Aguda/genética , Masculino , Inducción de Remisión , Tioguanina/uso terapéuticoRESUMEN
The CBP gene at 16p13 fuses to MOZ and MLL as a result of the t(8;16)(p11;p13) in acute (myelo)monocytic leukemias (AML M4/M5) and the t(11;16)(q23;p13) in treatment-related AML, respectively. We show here that a novel t(10;16)(q22;p13) in a childhood AML M5a leads to a MORF-CBP chimera. RT-PCR using MORF forward and CBP reverse primers amplified a MORF-CBP fusion in which nucleotide 3103 of MORF was fused in-frame with nucleotide 284 of CBP. Nested RT-PCR with CBP forward and MORF reverse primers generated a CBP-MORF transcript in which nucleotide 283 of CBP was fused in-frame with nucleotide 3104 of MORF. Genomic analyses revealed that the breaks were close to Alu elements in intron 16 of MORF and intron 2 of CBP and that duplications had occurred near the breakpoints. A database search using MORF cDNA enabled us to construct an exon-intron map of the MORF gene. The MORF-CBP protein retains the zinc fingers, two nuclear localization signals, the histone acetyltransferase (HAT) domain, a portion of the acidic domain of MORF and the CBP protein downstream of codon 29. Thus, the part of CBP encoding the RARA-binding domain, the CREB-binding domain, the three Cys/His-rich regions, the bromodomain, the HAT domain and the Glu-rich domains is present. In the reciprocal CBP-MORF, part of the acidic domain and the C-terminal Ser- and Met-rich regions of MORF are likely to be driven by the CBP promoter. Since both fusion transcripts were present, their exact role in the leukemogenic process remains to be elucidated.
Asunto(s)
Acetiltransferasas/genética , Cromosomas Humanos Par 10/genética , Cromosomas Humanos Par 16/genética , Leucemia Monocítica Aguda/enzimología , Leucemia Monocítica Aguda/genética , Proteínas Nucleares/genética , Proteínas de Fusión Oncogénica/genética , Proteínas de Saccharomyces cerevisiae , Transactivadores/genética , Translocación Genética/genética , Secuencia de Aminoácidos/genética , Secuencia de Bases/genética , Proteína de Unión a CREB , Preescolar , Bandeo Cromosómico , Femenino , Histona Acetiltransferasas , Humanos , Datos de Secuencia MolecularRESUMEN
Fluorescence in situ hybridization (FISH), including COBRA-FISH, was used to characterize 11 salivary gland tumors that had been investigated by banding analysis. Five cases were pleomorphic adenoma (PA), three were adenoid cystic carcinoma, and one case each was mucoepidermoid carcinoma, carcinoma ex-pleomorphic adenoma (CaPA), and adenocarcinoma. All 11 cases were selected on the basis that they had shown rearrangement of 6q or 9p or had unresolved aberrations after karyotyping. The COBRA-FISH and FISH analyses led to a revised karyotype in all informative cases and made it possible to clarify almost all chromosomal rearrangements occurring in the tumors. Of particular note were the confirmation of the existence of 6q deletions, a common change in salivary gland carcinomas, and the demonstration that a seemingly balanced t(6;9) resulted in del(6q). Other rearrangements that were revealed by FISH included amplification of 12q sequences (MDM2 and CDK4) in one PA. We also investigated the status of the PLAG1 gene in four cases (one PA, one CaPA, one adenoid cystic carcinoma, and one mucoepidermoid carcinoma) with 8q12 rearrangements. Only in the former two cases were the FISH results compatible with intragenic rearrangements. Overall, the results of the study show that, even with good banding quality and in karyotypes of modest complexity, much new information will be gained by supplementing the banding analysis with a multicolor FISH approach, such as COBRA-FISH.
Asunto(s)
Aberraciones Cromosómicas/genética , Hibridación Fluorescente in Situ/métodos , Neoplasias de las Glándulas Salivales/genética , Adulto , Anciano , Cromosomas Humanos Par 6/genética , Cromosomas Humanos Par 9/genética , Femenino , Humanos , Cariotipificación , Masculino , Persona de Mediana Edad , Translocación Genética/genéticaRESUMEN
The nosologic status of fibrous dysplasia (FD), a well-known and relatively common bone lesion, is controversial. Information collected by the CHromosomes And MorPhology (CHAMP) study group on published and unpublished cases of fibrous dysplasia shows the presence of clonal chromosome changes in at least a proportion of these lesions. The chromosome aberrations found in FD lesions have been quite variable and have included both structural and numerical changes. Two of the three cases investigated at the study group had trisomy 2 as the sole acquired anomaly. Combined with previously published data, +2 and rearrangements involving chromosome band 12p13 have each been detected in 3 of 8 cases with abnormal karyotype of 11 in which chromosomal analysis has been performed, suggesting that FD is a neoplastic lesion rather than a "dysplastic" process, as has been generally believed and as implied by its very name.