RESUMEN
A risk-adapted treatment strategy is mandatory for myelodysplastic syndromes (MDS). We refined the World Health Organization (WHO)-classification-based Prognostic Scoring System (WPSS) by determining the impact of the newer clinical and cytogenetic features, and we compared its prognostic power to that of the revised International Prognostic Scoring System (IPSS-R). A population of 5326 untreated MDS was considered. We analyzed single WPSS parameters and confirmed that the WHO classification and severe anemia provide important prognostic information in MDS. A strong correlation was found between the WPSS including the new cytogenetic risk stratification and WPSS adopting original criteria. We then compared WPSS with the IPSS-R prognostic system. A highly significant correlation was found between the WPSS and IPSS-R risk classifications. Discrepancies did occur among lower-risk patients in whom the number of dysplastic hematopoietic lineages as assessed by morphology did not reflect the severity of peripheral blood cytopenias and/or increased marrow blast count. Moreover, severe anemia has higher prognostic weight in the WPSS versus IPSS-R model. Overall, both systems well represent the prognostic risk of MDS patients defined by WHO morphologic criteria. This study provides relevant in formation for the implementation of risk-adapted strategies in MDS.
Asunto(s)
Síndromes Mielodisplásicos/clasificación , Síndromes Mielodisplásicos/diagnóstico , Organización Mundial de la Salud , Adolescente , Adulto , Anciano , Anciano de 80 o más Años , Terapia Combinada , Análisis Citogenético , Femenino , Estudios de Seguimiento , Humanos , Cooperación Internacional , Masculino , Persona de Mediana Edad , Síndromes Mielodisplásicos/mortalidad , Síndromes Mielodisplásicos/terapia , Estadificación de Neoplasias , Pronóstico , Proyectos de Investigación , Medición de Riesgo , Tasa de Supervivencia , Adulto JovenRESUMEN
Monosomal karyotype (MK) is associated with an adverse prognosis in patients in acute myeloid leukemia (AML). This study analyzes the prognostic impact of MK in a cohort of primary, untreated patients with myelodysplastic syndromes (MDS). A total of 431 patients were extracted from an international database. To analyze whether MK is an independent prognostic marker in MDS, cytogenetic and clinical data were explored in uni- and multivariate models regarding overall survival (OS) as well as AML-free survival. In all, 204/431 (47.3%) patients with MK were identified. Regarding OS, MK was prognostically significant in patients with ≤ 4 abnormalities only. In highly complex karyotypes (≥ 5 abnormalities), MK did not separate prognostic subgroups (median OS 4.9 months in MK+ vs 5.6 months in patients without MK, P=0.832). Based on the number of abnormalities, MK-positive karyotypes (MK+) split into different prognostic subgroups (MK+ and 2 abnormalities: OS 13.4 months, MK+ and 3 abnormalities: 8.0 months, MK+ and 4 abnormalities: 7.9 months and MK+ and ≥ 5 abnormalities: 4.9 months; P<0.01). In multivariate analyses, MK was not an independent prognostic factor. Our data support the hypothesis that a high number of complex abnormalities, associated with an instable clone, define the subgroup with the worst prognosis in MDS, independent of MK.
Asunto(s)
Aberraciones Cromosómicas , Monosomía/genética , Síndromes Mielodisplásicos/mortalidad , Adulto , Anciano , Anciano de 80 o más Años , Estudios de Cohortes , Femenino , Estudios de Seguimiento , Humanos , Cariotipificación , Masculino , Persona de Mediana Edad , Análisis Multivariante , Síndromes Mielodisplásicos/clasificación , Síndromes Mielodisplásicos/genética , Pronóstico , Tasa de Supervivencia , Adulto JovenRESUMEN
Patients with relapsed/refractory leukemias or advanced myelodysplastic syndrome (MDS) fare poorly following allogeneic hematopoietic cell transplant (HCT). We report prospective phase II study results of 29 patients given clofarabine 30 mg/m(2)/day i.v. × 5 days followed immediately by HCT conditioning while at the cytopenic nadir. A total of 15/29 patients (52%) were cytoreduced according to pre-defined criteria (cellularity <20% and blasts <10%). Marrow cellularity (P<0.0001) and blast% (P=0.03) were reduced. Toxicities were acceptable, with transient hyperbilirubinemia (48%) and gr3-4 infections (10%). In all, 28/29 proceeded to transplant; 27 received ATG or alemtuzumab. Post HCT, 180 day non-relapse mortality (NRM) was 7% (95% confidence interval (CI): 1-21), relapse was 29% (95% CI: 13-46) and OS was 71% (95% CI: 51-85), comparing favorably to published data for high-risk patients. Two-year graft vs host disease incidence was 40% (95% CI: 21-58) and 2 year OS was 31% (95% CI: 14-48). Disease at the nadir correlated with inferior OS after HCT (HR=1.22 for each 10% marrow blasts, 95% CI: 1.02-1.46). For AML/MDS patients, there was a suggestion that successful cytoreduction increased PFS (330 vs 171 days, P=0.3) and OS (375 vs 195 days, P=0.31). Clofarabine used as a bridge to HCT reduces disease burden, is well tolerated, and permits high-risk patients to undergo HCT with acceptable NRM. Late relapses are common; thus, additional strategies should be pursued. NCT-00724009.
Asunto(s)
Nucleótidos de Adenina/administración & dosificación , Arabinonucleósidos/administración & dosificación , Trasplante de Células Madre Hematopoyéticas/métodos , Síndromes Mielodisplásicos/terapia , Acondicionamiento Pretrasplante/métodos , Adulto , Anciano , Antimetabolitos Antineoplásicos/administración & dosificación , Clofarabina , Humanos , Persona de Mediana Edad , Síndromes Mielodisplásicos/tratamiento farmacológico , Síndromes Mielodisplásicos/cirugía , Recurrencia Local de Neoplasia/tratamiento farmacológico , Recurrencia Local de Neoplasia/cirugía , Recurrencia Local de Neoplasia/terapia , Estudios Prospectivos , Estudios Retrospectivos , Trasplante Homólogo , Adulto JovenRESUMEN
The PICALM (CALM) gene, whose product is involved in clathrin-mediated endocytosis, has been identified in two recurring chromosomal translocations, involving either MLL or MLLT10 (AF10). We developed a mouse model of CALM-AF10(+) leukemia to examine the hypothesis that disruption of endocytosis contributes to leukemogenesis. Exclusion of the C-terminal portion of CALM from the fusion protein, which is required for optimal binding to clathrin, resulted in the development of a myeloproliferative disease, whereas inclusion of this domain led to the development of acute myeloid leukemia and changes in gene expression of several cancer-related genes, notably Pim1 and Crebbp. Nonetheless, the development of leukemia could not be attributed directly to interference with endocytosis or consequential changes in proliferation and signaling. In leukemia cells, full-length CALM-AF10 localized to the nucleus with no consistent effect on growth factor endocyctosis, and suppressed histone H3 lysine 79 methylation regardless of the presence of clathrin. Using fluorescence resonance energy transfer analysis, we show that CALM-AF10 has a propensity to homo-oligomerize, raising the possibility that the function of endocytic proteins involved in chimeric fusions may be to provide dimerization properties, a recognized mechanism for unleashing oncogenic properties of chimeric transcription factors, rather than disrupting the internalization of growth factor receptors.
Asunto(s)
Clatrina/fisiología , Leucemia Mieloide Aguda/etiología , Proteínas de Fusión Oncogénica/fisiología , Animales , Endocitosis , Histonas/metabolismo , Humanos , Leucemia Mieloide Aguda/metabolismo , Leucemia Mieloide Aguda/patología , Ratones , Ratones Endogámicos BALB C , Proteínas de Fusión Oncogénica/química , Fenotipo , Multimerización de Proteína , Estructura Terciaria de Proteína , Proteínas Proto-Oncogénicas c-kit/metabolismo , Receptores de Factores de Crecimiento/metabolismoRESUMEN
FHL2 is a multifunctional LIM domain protein that acts as a transcriptional modulator mediating proliferation and apoptosis in a tissue-specific manner. Upregulation of FHL2 has been detected in a variety of cancers. We demonstrate that upregulation of FHL2 is associated with a subset of acute myeloid leukemia with a characteristic gene-expression signature, and abnormalities of chromosome 5. In mice, expression of endogenous Fhl2 is downregulated coordinately during the differentiation of hematopoietic cells. Upregulation of FHL2 enhances proliferation of myeloid progenitor cells, and serial-replating efficiency of hematopoietic cells in vitro. Chimeric mice with enforced expression of FHL2 in bone marrow cells, are characterized by an expanded pool of myeloid progenitor cells, enhanced granulopoiesis and megakaryocytopoiesis. In addition, enhanced expression of FHL2 promotes cell-cycle entry of myeloid progenitor cells and increases the frequency of apoptosis of bone marrow cells in vivo. These results raise the possibility that deregulation of FHL2 contributes to the development of human myeloid disorders.
Asunto(s)
Proteínas de Homeodominio/fisiología , Leucemia Mieloide Aguda/etiología , Proteínas Musculares/fisiología , Mielopoyesis , Factores de Transcripción/fisiología , Animales , Proliferación Celular , Hematopoyesis , Proteínas de Homeodominio/genética , Proteínas con Homeodominio LIM , Masculino , Ratones , Ratones Endogámicos BALB C , Ratones Endogámicos C57BL , Proteínas Musculares/genética , Células Progenitoras Mieloides , Trombopoyesis , Factores de Transcripción/genéticaRESUMEN
Hepatocyte nuclear factor-6 (HNF-6) is the ONECUT-homeodomain transcription factor that is enriched in liver and also present in pancreas and central nervous system. It is expressed in the pancreatic bud at E10.5. In adult pancreas, its expression is restricted to the exocrine pancreas and duct cells. Since duct cells are thought to be precursors of endocrine cells and HNF-6 is involved in the regulation of the expression of HNF-4alpha and -1beta, genes that cause maturity onset diabetes of the young (MODY), we hypothesized that the sustained expression of HNF-6 would affect beta-cell function. We generated transgenic mice over-expressing human HNF-6 using the mouse insulin I promoter (MIP). We obtained one female founder in which the transgene had been incorporated into two sites; the chromosome (Ch) 14 and the X chromosome. The integration site of the latter was within centromeric heterochromatin and the transgene was inactivated. Studies on mice in which the transgene was integrated into Ch14 showed beta-cell specific defects functionally and pathologically. The insulin secretory response to glucose and arginine in the in situ-perfused pancreas was also significantly impaired in these mice. Immunohistochemical analysis revealed that the islets were smaller and had an abnormal architecture with an inverted ratio of alpha- and beta-cells resulting from beta-cell loss to 30% by 6-wk of age. The decreased number of beta-cells was quantified first time by fluorescent activated cell sorting using entire pancreata from the transgenic mice crossed with MIP-green fluorescent protein (GFP) mice. This severe loss of beta-cells involved programmed cell death.
Asunto(s)
Apoptosis/genética , Regulación de la Expresión Génica/genética , Factor Nuclear 6 del Hepatocito/biosíntesis , Células Secretoras de Insulina/metabolismo , Transgenes , Animales , Sistema Nervioso Central/metabolismo , Embrión de Mamíferos/embriología , Embrión de Mamíferos/metabolismo , Embrión de Mamíferos/patología , Femenino , Glucosa/farmacología , Factor Nuclear 1-beta del Hepatocito/biosíntesis , Factor Nuclear 4 del Hepatocito/biosíntesis , Factor Nuclear 6 del Hepatocito/genética , Heterocromatina/genética , Heterocromatina/metabolismo , Humanos , Insulina/metabolismo , Secreción de Insulina , Células Secretoras de Insulina/patología , Hígado/metabolismo , Masculino , Ratones , Ratones Transgénicos , Especificidad de Órganos/fisiología , Edulcorantes/farmacología , Cromosoma X/genética , Cromosoma X/metabolismoRESUMEN
Cancer cells display an altered distribution of DNA methylation relative to normal cells. Certain tumor suppressor gene promoters are hypermethylated and transcriptionally inactivated, whereas repetitive DNA is hypomethylated and transcriptionally active. Little is understood about how the abnormal DNA methylation patterns of cancer cells are established and maintained. Here, we identify over 20 DNMT3B transcripts from many cancer cell lines and primary acute leukemia cells that contain aberrant splicing at the 5' end of the gene, encoding truncated proteins lacking the C-terminal catalytic domain. Many of these aberrant transcripts retain intron sequences. Although the aberrant transcripts represent a minority of the DNMT3B transcripts present, Western blot analysis demonstrates truncated DNMT3B isoforms in the nuclear protein extracts of cancer cells. To test if expression of a truncated DNMT3B protein could alter the DNA methylation patterns within cells, we expressed DNMT3B7, the most frequently expressed aberrant transcript, in 293 cells. DNMT3B7-expressing 293 cells have altered gene expression as identified by microarray analysis. Some of these changes in gene expression correlate with altered DNA methylation of corresponding CpG islands. These results suggest that truncated DNMT3B proteins could play a role in the abnormal distribution of DNA methylation found in cancer cells.
Asunto(s)
Empalme Alternativo , ADN (Citosina-5-)-Metiltransferasas/genética , Regulación Neoplásica de la Expresión Génica , Transcripción Genética , Western Blotting , Línea Celular , Línea Celular Tumoral , Análisis por Conglomerados , Islas de CpG/genética , ADN (Citosina-5-)-Metiltransferasas/metabolismo , Metilación de ADN , Perfilación de la Expresión Génica , Humanos , Neoplasias/genética , Neoplasias/patología , Análisis de Secuencia por Matrices de Oligonucleótidos , Isoformas de Proteínas/genética , Isoformas de Proteínas/metabolismo , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa , Transfección , ADN Metiltransferasa 3BAsunto(s)
Antimetabolitos Antineoplásicos/uso terapéutico , Citarabina/uso terapéutico , Perfilación de la Expresión Génica , Leucemia Mieloide Aguda/tratamiento farmacológico , Leucemia Mieloide Aguda/genética , Análisis de Secuencia por Matrices de Oligonucleótidos/métodos , Precursor de Proteína beta-Amiloide/genética , Reparación de la Incompatibilidad de ADN , Resistencia a Antineoplásicos , Humanos , Proteínas Proto-Oncogénicas c-bcl-2/genéticaRESUMEN
The impact of disease burden on the outcome of patients with acute myeloid leukemia (AML) undergoing allogeneic stem cell transplantation (SCT) has not been well defined. Data from several retrospective series suggest that overt leukemia at the time of transplant increases the risk of relapse. We reviewed the outcomes of 68 consecutive adults with AML (n=60) or myelodysplastic syndromes (MDS) (n=8) who received an allogeneic SCT at the University of Chicago between May 1986 and October 2002 to confirm the importance of currently recognized risk factors for overall survival (OS) and progression-free survival (PFS). In addition, we wanted to determine whether quantification of residual disease by blast percentage or cytogenetic abnormalities at the time of SCT was correlated with outcome. AML subtypes based on the FAB classification were as follows: M0=9, M1=9, M2=16, M3=2, M4=16, M5=3, M6=5. Cytogenetic analysis was available from 52 patients. Using standard morphologic criteria, 34 patients were in complete remission (CR) and 34 had visible leukemia present. The majority of donors were HLA-identical siblings (n=55). In all, 56 patients received myeloablative conditioning regimens and 12 received a reduced-intensity, fludarabine-based conditioning regimen. OS and PFS times were 7.1 months (95% CI, 4.8-10.4) and 5.1 months (95% CI, 3.2-7.8), respectively. Median follow-up from SCT was 4.6 years (range, 0.6-17.0) for survivors. In multivariate analysis, the following factors were found to be associated with worse survival: (1) increased percentage of blasts in the bone marrow at the time of SCT, (2) presence of acute graft-versus-host disease, (3) mismatched donor, (4) Zubrod performance score of >/=2, and (5) age >/=45 years. We also found a trend towards improved outcome among patients in cytogenetic remission as compared to those who had residual cytogenetic abnormalities and those in overt relapse. These data support an association between pre-transplant disease burden and poor outcome after SCT.
Asunto(s)
Trasplante de Células Madre Hematopoyéticas , Leucemia Mieloide Aguda/terapia , Síndromes Mielodisplásicos/terapia , Adulto , Anciano , Costo de Enfermedad , Femenino , Enfermedad Injerto contra Huésped/etiología , Prueba de Histocompatibilidad , Humanos , Leucemia Mieloide Aguda/mortalidad , Masculino , Persona de Mediana Edad , Síndromes Mielodisplásicos/mortalidad , Pronóstico , Trasplante HomólogoRESUMEN
Monosomy 7 and deletion of 7q are recurring abnormalities in malignant myeloid diseases. Here we extensively characterize an approximately 2-Mb commonly deleted segment (CDS) of 7q22 bounded by D7S1503 and D7S1841. Approximately 1.8 Mb of sequence have been generated from this interval, facilitating the construction of a transcript map that includes large numbers of genes and ESTs. The intron/exon organization of seven genes and expression patterns of three genes were determined, and leukemia samples were screened for mutations in five genes. We have used polymorphic markers from this region to examine leukemia cells for allelic loss within 7q22. Finally, we isolated mouse genomic clones orthologous to several of the characterized human genes. Fluorescence in situ hybridization studies using these clones indicate that a region of orthologous synteny lies on proximal mouse chromosome 5. These resources should greatly accelerate the pace of candidate gene discovery in this region.
Asunto(s)
Deleción Cromosómica , Cromosomas Humanos Par 7/genética , Leucemia Mieloide/genética , Síndromes Mielodisplásicos/genética , Enfermedad Aguda , Adulto , Animales , Niño , Cromosomas Artificiales Bacterianos , Cromosomas Artificiales de Bacteriófagos P1 , Clonación Molecular , Biología Computacional , Mapeo Contig , Exones , Etiquetas de Secuencia Expresada , Expresión Génica , Perfilación de la Expresión Génica , Humanos , Hibridación Fluorescente in Situ , Intrones , Ratones , Datos de Secuencia Molecular , Monosomía , Mutación , SinteníaRESUMEN
The myelodysplastic syndromes are a collection of five clinico-pathological entities with a wide spectrum of clinical behaviours and survival outcomes. Cytogenetic analysis has been instrumental in refining the prognosis, predicting the likelihood of progression to acute myeloid leukaemia and median survival, and in establishing clonality of these diseases. This review highlights the most frequent abnormalities and summarizes their clinical and genetic features.
Asunto(s)
Análisis Citogenético , Síndromes Mielodisplásicos/genética , Aberraciones Cromosómicas/clasificación , Células Clonales/patología , Análisis Citogenético/métodos , Humanos , Síndromes Mielodisplásicos/clasificación , Síndromes Mielodisplásicos/diagnóstico , PronósticoRESUMEN
During fluorescence in situ hybridization (FISH) analysis of metaphase cells from 70 patients with lymphoid and myeloid hematologic malignancies and chromosomal rearrangements involving band 12p13, we identified nine patients (four with lymphoid malignancies, four with myeloid malignancies and one with biphenotypic leukemia) who showed more complicated rearrangements than we had expected from conventional cytogenetic study. In six patients, multiple breaks occurred in small segments of 12p with subsequent translocations and insertions of these segments into other chromosomes, sometimes to unexpected regions. In three patients additional chromosome breaks resulted in a sub-clone which was cytogenetically indistinguishable from the main clone in each patient based on the cytogenetic analysis. These subtle molecular events were detected exclusively in a region covering TEL/ETV6 and KIP1/CDKN1B. Seven of nine had a previous history of chemo/radiotherapy; all the patients showed complex karyotypes, even though they were newly diagnosed with leukemia. Survival data were available in five patients, and all survived less than 6 months. These findings suggest that the 12p13 region, especially the above-mentioned region, is genetically unstable and fragile. It is likely that multiple chromosome breaks were induced through mutagens used in chemo/ radiotherapy, and are associated with a sub-group of patients with an extremely bad prognosis.
Asunto(s)
Fragilidad Cromosómica , Cromosomas Humanos Par 12 , Neoplasias Hematológicas/genética , Reordenamiento Génico , HumanosRESUMEN
Antigens that are tumor specific yet retained by tumor cells despite tumor progression offer stable and specific targets for immunologic and possibly other therapeutic interventions. Therefore, we have studied two CD4(+) T cell-recognized tumor-specific antigens that were retained during evolution of two ultraviolet-light-induced murine cancers to more aggressive growth. The antigens are ribosomal proteins altered by somatic tumor-specific point mutations, and the progressor (PRO) variants lack the corresponding normal alleles. In the first tumor, 6132A-PRO, the antigen is encoded by a point-mutated L9 ribosomal protein gene. The tumor lacks the normal L9 allele because of an interstitial deletion from chromosome 5. In the second tumor, 6139B-PRO, both alleles of the L26 gene have point mutations, and each encodes a different tumor-specific CD4(+) T cell-recognized antigen. Thus, for both L9 and L26 genes, we observe "two hit" kinetics commonly observed in genes suppressing tumor growth. Indeed, reintroduction of the lost wild-type L9 allele into the 6132A-PRO variant suppressed the growth of the tumor cells in vivo. Since both L9 and L26 encode proteins essential for ribosomal biogenesis, complete loss of the tumor-specific target antigens in the absence of a normal allele would abrogate tumor growth.
Asunto(s)
Antígenos de Neoplasias/genética , Antígenos de Neoplasias/metabolismo , Mutación Puntual , Alelos , Secuencia de Aminoácidos , Animales , Secuencia de Bases , Linfocitos T CD4-Positivos/inmunología , Cartilla de ADN/genética , ADN de Neoplasias/genética , Hibridación Fluorescente in Situ , Ratones , Datos de Secuencia Molecular , Neoplasias Inducidas por Radiación/etiología , Neoplasias Inducidas por Radiación/genética , Neoplasias Inducidas por Radiación/metabolismo , ARN Mensajero/genética , ARN Mensajero/metabolismo , ARN Neoplásico/genética , ARN Neoplásico/metabolismo , Proteínas Ribosómicas/genética , Proteínas Ribosómicas/inmunología , Proteínas Ribosómicas/metabolismo , Células Tumorales Cultivadas , Rayos Ultravioleta/efectos adversosRESUMEN
Structural alterations in 3q27 affecting the BCL6 locus are among the most frequent changes in B-NHL. The aim of the present study was to establish an interphase-FISH assay for the detection of all diverse BCL6 translocations in B-NHL. Two different approaches were tested, one using a PAC-clone spanning the major breakpoint region (MBR) of BCL6 (span-assay), and another using two BAC clones flanking the MBR (flank-assay). Interphase FISH with the span-assay detected the various BCL6 translocations in seven B-NHL cell lines. The dual-color flank-assay was evaluated in two laboratories independently: in normal controls, the cutoff level for false-positive signals was 2.6%, whereas the cutoff level for false-negatives in the seven cell lines was 7.5%. To test the feasibility of the FISH strategies, 30 samples from patients with B-NHL with cytogenetic abnormalities of 3q27 were evaluated with both assays. In 21 cases, the span-assay indicated a BCL6 rearrangement. In 18 of the 21 cases, the dual-color flank-assay confirmed the translocation including 12 different partner chromosomal loci. The three false-positive cases detected with the span-assay showed trisomy of chromosome 3 by cytogenetic analyses, and they were correctly classified as non-rearranged with the flank-assay. In summary, our FISH strategy using two differently labeled flanking BCL6 BAC probes provides a robust, sensitive, and reproducible method for the detection of common and uncommon abnormalities of BCL6 gene in interphase nuclei. The routine application of this assay to patients with B-NHL will allow the assessment of the diagnostic and prognostic significance of BCL6 rearrangements.
Asunto(s)
Cromosomas Humanos Par 3 , Linfoma de Células B/genética , Translocación Genética , Secuencia de Bases , Bandeo Cromosómico , Femenino , Reordenamiento Génico , Humanos , Hibridación Fluorescente in Situ , Cariotipificación , Masculino , Datos de Secuencia MolecularRESUMEN
Introducing dominant oncogenic alterations uncovered in human myeloid malignancies into the mouse germline provides a powerful approach for studying leukemogenesis. However, little is known about how gene inactivation contributes to the development of myeloid malignancies. We describe how Nf1 mutant mice provide one example in which disrupting a tumor suppressor gene has been used to generate an informative murine leukemia model. We also discuss how chromosome engineering technologies are being harnessed to model the segmental deletions found in myeloid malignancies, and how these approaches can be combined with retrovirally medicated insertional mutagenesis to generate new models and for gene discovery.
Asunto(s)
Modelos Animales de Enfermedad , Genes Supresores de Tumor , Leucemia Mieloide/genética , Animales , Deleción Cromosómica , Humanos , Ratones , Ratones MutantesAsunto(s)
Neoplasias Hematológicas/genética , Animales , Deleción Cromosómica , Cromosomas Humanos Par 5 , Proteínas de Unión al ADN/genética , Proteínas de Unión al ADN/metabolismo , Genes Supresores de Tumor , Genes bcl-2 , Neoplasias Hematológicas/patología , Humanos , Factores de Transcripción de Tipo Kruppel , Leucemia Promielocítica Aguda/genética , Linfoma de Células B/genética , Linfoma de Células T/genética , Proteínas de la Membrana/genética , FN-kappa B/genética , Proteína de la Leucemia Promielocítica con Dedos de Zinc , Proteínas Proto-Oncogénicas/genética , Proteínas Proto-Oncogénicas/metabolismo , Proteínas Proto-Oncogénicas c-rel/genética , Receptores de Superficie Celular/genética , Receptores Notch , Receptores de Ácido Retinoico/genética , Proteínas Recombinantes de Fusión/genética , Receptor alfa de Ácido Retinoico , Transactivadores/genética , Transactivadores/metabolismo , Factores de Transcripción/genética , Factores de Transcripción/metabolismo , Transcripción Genética , Translocación GenéticaRESUMEN
Loss of a whole chromosome 5, or a del(5q), are recurring abnormalities in malignant myeloid diseases. In previous studies, we defined a commonly deleted segment (CDS) of 1.5 Mb between D5S479 and D5S500 in patients with a del(5q), and we established a P1 artificial chromosome-based contig encompassing this interval. To identify candidate tumor suppressor genes (TSGs), we developed a transcript map of the CDS. The map contains 18 genes and 12 expressed sequence tags/UniGenes. Among the 18 genes are 10 genes that were previously cloned and 8 novel genes. The newly identified genes include CDC23, which encodes a component of the anaphase-promoting complex; RAB6KIFL, which encodes a kinesin-like protein involved in organelle transport; and KLHL3, which encodes a human homologue of the Drosophila ring canal protein, kelch. We determined the intron/exon organization of 14 genes and eliminated each gene as a classical TSG by mutation analysis. In addition, we established a single-nucleotide polymorphism map as well as a map of the mouse genome that is syntenic to the CDS of human 5q31. The development of a transcription map will facilitate the molecular cloning of a myeloid leukemia suppressor gene on 5q.
Asunto(s)
Deleción Cromosómica , Cromosomas Humanos Par 5/genética , Leucemia Mieloide/genética , Síndromes Mielodisplásicos/genética , Mapeo Físico de Cromosoma , Enfermedad Aguda , Proteínas Adaptadoras Transductoras de Señales , Animales , Subunidad Apc8 del Ciclosoma-Complejo Promotor de la Anafase , Proteínas Portadoras/genética , Proteínas de Ciclo Celular/genética , Cromosomas Artificiales Humanos , Análisis Mutacional de ADN , Biblioteca de Genes , Genes Supresores de Tumor , Humanos , Cinesinas/genética , Ratones , Proteínas de Microfilamentos , Datos de Secuencia MolecularRESUMEN
Low-grade B cell lymphomas of mucosa-associated lymphoid tissue (MALT) represent a distinct clinicopathological entity that arises in a wide variety of extranodal sites. Genetically, MALT lymphomas are characterized by the t(11;18)(q21;q21). The genes involved in this translocation have been identified to be API2 on chromosome 11, which encodes an apoptotic inhibitor, and MALT1, a novel gene on chromosome 18. We identified the t(11;18)(q21;q21) by Southern blot analysis and reverse transcriptase PCR in 42% of a panel of extranodal MALT lymphomas. We also identified the breakpoints within the API2 and MALT1 genes in 7 patients, which revealed a consistent breakpoint after the third baculoviral inhibitor of apoptosis repeat domain within API2, and variable breakpoints in MALT1. We determined the API2/MALT1 fusion transcript in 2 cases by Northern blot analysis and also showed that MALT1 mRNA is constitutively expressed in a variety of human tissues. To understand the functional consequence of the translocation, we determined the pattern of expression of API2 and MALT1 through B lineage differentiation. API2 was expressed only in cell lines which correspond to mature B cells, whereas MALT1 mRNA was detectable in pre-B cells, mature B cells and plasma cells. These results suggest that fusion of MALT1 to API2 mediated by the t(11;18)(q21;q21) may result in an increased inhibition of germinal center B cell apoptosis and subsequent development of MALT lymphomas.
Asunto(s)
Apoptosis , Linfoma de Células B de la Zona Marginal/genética , Proteínas de Neoplasias/metabolismo , Proteínas de Fusión Oncogénica/metabolismo , Proteínas/metabolismo , Linfocitos B/metabolismo , Northern Blotting , Southern Blotting , Caspasas , Diferenciación Celular , Expresión Génica , Humanos , Proteínas Inhibidoras de la Apoptosis , Linfoma de Células B de la Zona Marginal/patología , Proteína 1 de la Translocación del Linfoma del Tejido Linfático Asociado a Mucosas , Proteínas de Neoplasias/genética , Proteínas de Fusión Oncogénica/genética , Proteínas/genética , ARN/análisis , Análisis de Secuencia de ARN , Translocación GenéticaRESUMEN
Loss of a whole chromosome 5, or a del(5q), is a recurring abnormality in malignant myeloid diseases. By cytogenetic and molecular analyses, we delineated previously a 1- to 1.5-Mb region that is deleted in all patients with a del(5q). In our efforts to identify a myeloid tumor suppressor gene within the commonly deleted segment (CDS), we have cloned and characterized the genes encoding three putative nuclear proteins, each of which contains a bipartite nuclear localization signal (NLS). In addition, C5ORF5 contains a putative rhoGAP domain at the N-terminus, C5ORF6 has a proline-rich sequence near the N-terminus, and C5ORF7 has a zinc-finger domain that partially overlaps the NLS. All three genes are ubiquitously expressed and encode novel proteins. The C5ORF5 cDNA is 5.47 kb encoding a protein of 915 amino acids (aa) with a predicted molecular mass of approximately 105 kDa. C5ORF5 has 23 exons spanning over 27 kb. The C5ORF6 transcript is 4.1 kb encoding a protein of 392 aa with a predicted molecular mass of approximately 43 kDa. C5ORF6 has 5 exons and spans approximately 11 kb. The C5ORF7 cDNA is 6.3 kb and encodes a protein of 1417 aa with a predicted molecular mass of approximately 155 kDa. C5ORF7 has 24 exons spanning approximately 64 kb. All three genes were localized to the distal half of the CDS between D5S1983 and D5S500. We evaluated each as a candidate tumor suppressor gene by the analysis of myeloid leukemia cells from patients with -5/del(5q), but no inactivating mutations were identified.
Asunto(s)
Cromosomas Humanos Par 5 , Genes Supresores de Tumor , Leucemia Mieloide/genética , Síndromes Mielodisplásicos/genética , Proteínas Nucleares/genética , Secuencia de Aminoácidos , Mapeo Cromosómico , Humanos , Datos de Secuencia Molecular , Señales de Localización Nuclear , Polimorfismo Conformacional Retorcido-Simple , Homología de Secuencia de AminoácidoRESUMEN
The development of molecular hybridization techniques such as fluorescence in situ hybridization (FISH) has had a major Impact on efforts to detect and characterize the genetic changes that give rise to human tumors. With probes designed to Identify specific chromosomes and chromosomal regions, FISH is used routinely by cytogenetics and pathology laboratories to identify recurring chromosomal abnormalities associated with hematologic malignant diseases. In many cases FISH analysis provides increased sensitivity, in that cytogenetic abnormalities have been found In samples that appeared to be normal by morphologic and conventional cytogenetic examination. The combination of cytogenetic, FISH, and molecular analyses provides a powerful approach for diagnosing and subclassifying malignant diseases into clinically and biologically relevant subgroups, In selecting appropriate therapy, and in monitoring the efficacy of therapeutic regimens.