RESUMEN
While initial therapy of mantle cell lymphoma (MCL) is not standardized, bendamustine-rituximab (BR) is commonly used in older patients. Rituximab (R) maintenance following induction is often utilized. Thus, the open-label, randomized phase II ECOG-ACRIN Cancer Research Group E1411 trial was designed to test two questions: 1) Does addition of bortezomib to BR induction (BVR) and/or 2) addition of lenalidomide to rituximab (LR) maintenance improve progression-free survival (PFS) in patients with treatment-naïve MCL? From 2012-2016, 373 previously untreated patients, 87% ≥ 60 years old, were enrolled in this trial. At a median follow up of 7.5 years, there is no difference in the median PFS of BR compared to BVR (5.5 yrs vs. 6.4 yrs, HR 0.90, 90% CI 0.70, 1.16). There were no unexpected additional toxicities with BVR treatment compared to BR, with no impact on total dose/duration of treatment received. Independent of the induction treatment, addition of lenalidomide to rituximab did not significantly improve PFS, with median PFS in R vs LR (5.9 yrs vs 7.2 yrs, HR 0.84 90% CI 0.62, 1.15). The majority of patients completed the planned 24 cycles of LR at the scheduled dose. In summary, adding bortezomib to BR induction does not prolong PFS in treatment-naïve MCL, and LR maintenance was not associated with longer PFS compared with rituximab alone following BR. Nonetheless, the > 5 year median PFS outcomes in this prospective cooperative group trial indicate the efficacy of BR followed by rituximab maintenance as highly effective initial therapy for older MCL patients. (NCT01415752).
RESUMEN
Epstein-Barr virus (EBV) is a ubiquitous herpesvirus that typically causes asymptomatic infection but can promote B lymphoid tumors in the immune suppressed. In vitro, EBV infection of primary B cells stimulates glycolysis during immortalization into lymphoblastoid cell lines (LCLs). Lactate export during glycolysis is crucial for continued proliferation of many cancer cells-part of a phenomenon known as the "Warburg effect"- and is mediated by monocarboxylate transporters (MCTs). However, the role of MCTs has yet to be studied in EBV-associated malignancies, which display Warburg-like metabolism in vitro. Here, we show that EBV infection of B lymphocytes directly promotes temporal induction of MCT1 and MCT4 through the viral proteins EBNA2 and LMP1, respectively. Functionally, MCT1 was required for early B cell proliferation, and MCT4 up-regulation promoted acquired resistance to MCT1 antagonism in LCLs. However, dual MCT1/4 inhibition led to LCL growth arrest and lactate buildup. Metabolic profiling in LCLs revealed significantly reduced oxygen consumption rates (OCRs) and NAD+/NADH ratios, contrary to previous observations of increased OCR and unaltered NAD+/NADH ratios in MCT1/4-inhibited cancer cells. Furthermore, U-13C6-glucose labeling of MCT1/4-inhibited LCLs revealed depleted glutathione pools that correlated with elevated reactive oxygen species. Finally, we found that dual MCT1/4 inhibition also sensitized LCLs to killing by the electron transport chain complex I inhibitors phenformin and metformin. These findings were extended to viral lymphomas associated with EBV and the related gammaherpesvirus KSHV, pointing at a therapeutic approach for targeting both viral lymphomas.
Asunto(s)
Linfoma/metabolismo , Linfoma/virología , Transportadores de Ácidos Monocarboxílicos/antagonistas & inhibidores , Linfocitos B/virología , Línea Celular Tumoral , Proliferación Celular , Infecciones por Virus de Epstein-Barr/virología , Glucosa/metabolismo , Glutatión/metabolismo , Herpesvirus Humano 4/fisiología , Herpesvirus Humano 8/fisiología , Humanos , Ácido Láctico/metabolismo , Linfoma/patología , Metformina/farmacología , NAD/metabolismo , Consumo de Oxígeno , Fenformina/farmacología , Especies Reactivas de Oxígeno/metabolismo , Regulación hacia ArribaRESUMEN
Burkitt lymphoma (BL) is an aggressive, MYC-driven lymphoma comprising 3 distinct clinical subtypes: sporadic BLs that occur worldwide, endemic BLs that occur predominantly in sub-Saharan Africa, and immunodeficiency-associated BLs that occur primarily in the setting of HIV. In this study, we comprehensively delineated the genomic basis of BL through whole-genome sequencing (WGS) of 101 tumors representing all 3 subtypes of BL to identify 72 driver genes. These data were additionally informed by CRISPR screens in BL cell lines to functionally annotate the role of oncogenic drivers. Nearly every driver gene was found to have both coding and non-coding mutations, highlighting the importance of WGS for identifying driver events. Our data implicate coding and non-coding mutations in IGLL5, BACH2, SIN3A, and DNMT1. Epstein-Barr virus (EBV) infection was associated with higher mutation load, with type 1 EBV showing a higher mutational burden than type 2 EBV. Although sporadic and immunodeficiency-associated BLs had similar genetic profiles, endemic BLs manifested more frequent mutations in BCL7A and BCL6 and fewer genetic alterations in DNMT1, SNTB2, and CTCF. Silencing mutations in ID3 were a common feature of all 3 subtypes of BL. In vitro, mass spectrometry-based proteomics demonstrated that the ID3 protein binds primarily to TCF3 and TCF4. In vivo knockout of ID3 potentiated the effects of MYC, leading to rapid tumorigenesis and tumor phenotypes consistent with those observed in the human disease.
Asunto(s)
Linfoma de Burkitt/genética , Secuenciación Completa del Genoma/métodos , Animales , Humanos , RatonesRESUMEN
BACKGROUND: Significant racial differences have been observed in the incidence and clinical outcomes of diffuse large B-cell lymphoma (DLBCL) in the United States, but to the authors' knowledge it remains unclear whether genomic differences contribute to these disparities. METHODS: To understand the influences of genetic ancestry on tumor genomic alterations, the authors estimated the genetic ancestry of 1001 previously described patients with DLBCL using unsupervised model-based Admixture global ancestry analysis applied to exome sequencing data and examined the mutational profile of 150 DLBCL driver genes in tumors obtained from this cohort. RESULTS: Global ancestry prediction identified 619 patients with >90% European ancestry, 81 patients with >90% African ancestry, and 50 patients with >90% Asian ancestry. Compared with patients with DLBCL with European ancestry, patients with African ancestry were aged >10 years younger at the time of diagnosis and were more likely to present with B symptoms, elevated serum lactate dehydrogenase, extranodal disease, and advanced stage disease. Patients with African ancestry demonstrated worse overall survival compared with patients with European ancestry (median, 4.9 years vs 8.8 years; P = .04). Recurrent mutations of MLL2 (KMT2D), HIST1H1E, MYD88, BCL2, and PIM1 were found across all ancestry groups, suggesting shared mechanisms underlying tumor biology. The authors also identified 6 DLBCL driver genes that were more commonly mutated in patients with African ancestry compared with patients with European ancestry: ATM (21.0% vs 7.75%; P < .001), MGA (19.7% vs 5.33%; P < .001), SETD2 (17.3% vs 5.17%; P < .001), TET2 (12.3% vs 5.82%; P = .029), MLL3 (KMT2C) (11.1% vs 4.36%; P = .013), and DNMT3A (11.1% vs 4.52%; P = .016). CONCLUSIONS: Distinct prevalence and patterns of mutation highlight an important difference in the mutational landscapes of DLBCL arising in different ancestry groups. To the authors' knowledge, the results of the current study provide the first-ever characterization of genetic alterations among patients with African descent who are diagnosed with DLBCL.
Asunto(s)
Genoma Humano/genética , Linfoma de Células B Grandes Difuso/epidemiología , Linfoma de Células B Grandes Difuso/genética , Pronóstico , Adulto , Anciano , Pueblo Asiatico/genética , Población Negra/genética , Estudios de Cohortes , Proteínas de Unión al ADN/genética , Supervivencia sin Enfermedad , Exoma/genética , Femenino , Histonas/genética , Humanos , Linfoma de Células B Grandes Difuso/patología , Masculino , Persona de Mediana Edad , Mutación/genética , Factor 88 de Diferenciación Mieloide/genética , Proteínas de Neoplasias/genética , Proteínas Proto-Oncogénicas c-bcl-2/genética , Población Blanca/genética , Secuenciación del Exoma , Adulto JovenRESUMEN
Lymphoma incidence in sub-Saharan Africa (SSA) is increasing due to HIV and population aging. Diffuse Large B-cell lymphoma (DLBCL), the most common lymphoma in SSA and worldwide, is highly associated with HIV, but molecular studies of HIV-associated DLBCL are scarce globally. We describe profiling of DLBCL from Malawi, aiming to elucidate tumor biology and identify clinically meaningful biomarkers specifically for SSA. Between June 1, 2013 and June 1, 2016, 59 cases of DLBCL (32 HIV+/27 HIV-) enrolled in the Kamuzu Central Hospital Lymphoma Study were characterized, of which 54 (92%) were negative for Epstein-Barr virus. Gene expression profiling (GEP) by whole transcriptome sequencing was performed on the first 36 cases (22 HIV+/14 HIV-). Immunohistochemistry (IHC) and GEP results were compared with published data and correlated to clinical outcome and pathologic features. Unsupervised clustering strongly segregated DLBCL by HIV status (p = 0.0003, Chi-squared test), indicating a marked contribution of HIV to expression phenotype. Pathway analysis identified that HIV-associated tumors were enriched in hypoxia, oxidative stress, and metabolism related gene expression patterns. Cell-of-origin subtype, determined by sequencing and IHC, did not associate with differences in overall survival (OS), while Ki-67 proliferation index ≥80% was associated with inferior OS in HIV+ DLBCL only (p = 0.03) and cMYC/BCL2 co-expression by IHC was negatively prognostic across the entire cohort (p = 0.01). This study provides among the first molecular characterizations of DLBCL from SSA, demonstrates marked gene expression differences by HIV status, and identifies genomic and immunophenotypic characteristics that can inform future basic and clinical investigations.
Asunto(s)
Biomarcadores de Tumor/análisis , Infecciones por VIH/complicaciones , Linfoma de Células B Grandes Difuso/virología , Adolescente , Adulto , Anciano , Niño , Estudios de Cohortes , Femenino , Perfilación de la Expresión Génica , Humanos , Linfoma de Células B Grandes Difuso/genética , Linfoma de Células B Grandes Difuso/patología , Malaui , Masculino , Persona de Mediana Edad , Pronóstico , Transcriptoma , Adulto JovenRESUMEN
Within the liver a single Plasmodium parasite transforms into thousands of blood-infective forms to cause malaria. Here, we use RNA-sequencing to identify host genes that are upregulated upon Plasmodium berghei infection of hepatocytes with the hypothesis that host pathways are hijacked to benefit parasite development. We found that expression of aquaporin-3 (AQP3), a water and glycerol channel, is significantly induced in Plasmodium-infected hepatocytes compared to uninfected cells. This aquaglyceroporin localizes to the parasitophorous vacuole membrane, the compartmental interface between the host and pathogen, with a temporal pattern that correlates with the parasite's expansion in the liver. Depletion or elimination of host AQP3 expression significantly reduces P. berghei parasite burden during the liver stage and chemical disruption by a known AQP3 inhibitor, auphen, reduces P. falciparum asexual blood stage and P. berghei liver stage parasite load. Further use of this inhibitor as a chemical probe suggests that AQP3-mediated nutrient transport is an important function for parasite development. This study reveals a previously unknown potential route for host-dependent nutrient acquisition by Plasmodium which was discovered by mapping the transcriptional changes that occur in hepatocytes throughout P. berghei infection. The dataset reported may be leveraged to identify additional host factors that are essential for Plasmodium liver stage infection and highlights Plasmodium's dependence on host factors within hepatocytes.
Asunto(s)
Acuaporina 3/metabolismo , Plasmodium berghei/metabolismo , Animales , Acuaporina 3/fisiología , Células Hep G2 , Hepatocitos/metabolismo , Hepatocitos/parasitología , Humanos , Hígado/metabolismo , Hígado/parasitología , Hepatopatías , Malaria/parasitología , Ratones , Parásitos/metabolismo , Plasmodium berghei/genética , Plasmodium berghei/parasitología , Proteínas Protozoarias/metabolismo , Análisis de Secuencia de ARN/métodos , Esporozoítos/metabolismo , Vacuolas/metabolismoRESUMEN
PURPOSE OF REVIEW: We review the genetic foundations of different rare lymphomas to examine their shared origins. These data indicate the potential application of genomics to improve the diagnosis and treatment of these rare diseases. RECENT FINDINGS: Next generation sequencing technologies have provided an important window into the genetic underpinnings of lymphomas. A growing body of evidence indicates that although some genetic alterations are specific to certain diseases, others are shared across different lymphomas. Many such genetic events have already demonstrated clinical utility, such as BRAF V600E that confers sensitivity to vemurafenib in patients with hairy cell leukemia. SUMMARY: The rareness of many lymphoma subtypes makes the conduct of clinical trials and recruitment of significant numbers of patients impractical. However, a knowledge of the shared genetic origins of these rare lymphomas has the potential to inform 'basket' clinical trials in which multiple lymphoma subtypes are included. These trials would include patients based on the presence of alterations in targetable driver genes. Such approaches would be greatly strengthened by a systematic assessment of significant patient numbers from each subtype using next generation sequencing.
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Secuenciación de Nucleótidos de Alto Rendimiento , Linfoma , Mutación Missense , Proteínas Proto-Oncogénicas B-raf , Vemurafenib/uso terapéutico , Sustitución de Aminoácidos , Animales , Humanos , Linfoma/clasificación , Linfoma/tratamiento farmacológico , Linfoma/genética , Linfoma/metabolismo , Proteínas Proto-Oncogénicas B-raf/genética , Proteínas Proto-Oncogénicas B-raf/metabolismo , Enfermedades Raras/clasificación , Enfermedades Raras/tratamiento farmacológico , Enfermedades Raras/genética , Enfermedades Raras/metabolismoRESUMEN
GNA13 is the most frequently mutated gene in germinal center (GC)-derived B-cell lymphomas, including nearly a quarter of Burkitt lymphoma and GC-derived diffuse large B-cell lymphoma. These mutations occur in a pattern consistent with loss of function. We have modeled the GNA13-deficient state exclusively in GC B cells by crossing the Gna13 conditional knockout mouse strain with the GC-specific AID-Cre transgenic strain. AID-Cre(+) GNA13-deficient mice demonstrate disordered GC architecture and dark zone/light zone distribution in vivo, and demonstrate altered migration behavior, decreased levels of filamentous actin, and attenuated RhoA activity in vitro. We also found that GNA13-deficient mice have increased numbers of GC B cells that display impaired caspase-mediated cell death and increased frequency of somatic hypermutation in the immunoglobulin VH locus. Lastly, GNA13 deficiency, combined with conditional MYC transgene expression in mouse GC B cells, promotes lymphomagenesis. Thus, GNA13 loss is associated with GC B-cell persistence, in which impaired apoptosis and ongoing somatic hypermutation may lead to an increased risk of lymphoma development.
Asunto(s)
Linfocitos B/metabolismo , Subunidades alfa de la Proteína de Unión al GTP/metabolismo , Centro Germinal/metabolismo , Linfoma de Células B/metabolismo , Animales , Linfocitos B/patología , Subunidades alfa de la Proteína de Unión al GTP/genética , Centro Germinal/patología , Cadenas Pesadas de Inmunoglobulina/genética , Cadenas Pesadas de Inmunoglobulina/metabolismo , Región Variable de Inmunoglobulina/genética , Región Variable de Inmunoglobulina/metabolismo , Linfoma de Células B/genética , Linfoma de Células B/patología , Masculino , Ratones , Ratones Noqueados , Proteínas Proto-Oncogénicas c-myc/biosíntesis , Proteínas Proto-Oncogénicas c-myc/genéticaRESUMEN
BACKGROUND: Ibrutinib is an irreversible inhibitor of Bruton's tyrosine kinase (BTK) and is effective in chronic lymphocytic leukemia (CLL). Resistance to irreversible kinase inhibitors and resistance associated with BTK inhibition have not been characterized. Although only a small proportion of patients have had a relapse during ibrutinib therapy, an understanding of resistance mechanisms is important. We evaluated patients with relapsed disease to identify mutations that may mediate ibrutinib resistance. METHODS: We performed whole-exome sequencing at baseline and the time of relapse on samples from six patients with acquired resistance to ibrutinib therapy. We then performed functional analysis of identified mutations. In addition, we performed Ion Torrent sequencing for identified resistance mutations on samples from nine patients with prolonged lymphocytosis. RESULTS: We identified a cysteine-to-serine mutation in BTK at the binding site of ibrutinib in five patients and identified three distinct mutations in PLCγ2 in two patients. Functional analysis showed that the C481S mutation of BTK results in a protein that is only reversibly inhibited by ibrutinib. The R665W and L845F mutations in PLCγ2 are both potentially gain-of-function mutations that lead to autonomous B-cell-receptor activity. These mutations were not found in any of the patients with prolonged lymphocytosis who were taking ibrutinib. CONCLUSIONS: Resistance to the irreversible BTK inhibitor ibrutinib often involves mutation of a cysteine residue where ibrutinib binding occurs. This finding, combined with two additional mutations in PLCγ2 that are immediately downstream of BTK, underscores the importance of the B-cell-receptor pathway in the mechanism of action of ibrutinib in CLL. (Funded by the National Cancer Institute and others.).
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Resistencia a Antineoplásicos/genética , Leucemia Linfocítica Crónica de Células B/genética , Fosfolipasa C gamma/genética , Mutación Puntual , Proteínas Tirosina Quinasas/genética , Pirazoles/uso terapéutico , Pirimidinas/uso terapéutico , Adenina/análogos & derivados , Agammaglobulinemia Tirosina Quinasa , Anciano , Sitios de Unión/genética , Exoma , Humanos , Leucemia Linfocítica Crónica de Células B/tratamiento farmacológico , Persona de Mediana Edad , Fosfolipasa C gamma/metabolismo , Piperidinas , Proteínas Tirosina Quinasas/antagonistas & inhibidores , Pirazoles/farmacología , Pirimidinas/farmacología , Receptores de Antígenos de Linfocitos B/metabolismo , Recurrencia , Análisis de Secuencia de ADNRESUMEN
In this study, we define the genetic landscape of mantle cell lymphoma (MCL) through exome sequencing of 56 cases of MCL. We identified recurrent mutations in ATM, CCND1, MLL2, and TP53. We further identified a number of novel genes recurrently mutated in patients with MCL including RB1, WHSC1, POT1, and SMARCA4. We noted that MCLs have a distinct mutational profile compared with lymphomas from other B-cell stages. The ENCODE project has defined the chromatin structure of many cell types. However, a similar characterization of primary human mature B cells has been lacking. We defined, for the first time, the chromatin structure of primary human naïve, germinal center, and memory B cells through chromatin immunoprecipitation and sequencing for H3K4me1, H3K4me3, H3Ac, H3K36me3, H3K27me3, and PolII. We found that somatic mutations that occur more frequently in either MCLs or Burkitt lymphomas were associated with open chromatin in their respective B cells of origin, naïve B cells, and germinal center B cells. Our work thus elucidates the landscape of gene-coding mutations in MCL and the critical interplay between epigenetic alterations associated with B-cell differentiation and the acquisition of somatic mutations in cancer.
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Linfocitos B/metabolismo , Cromatina/genética , Genómica , Linfoma de Células del Manto/genética , Mutación , Proteínas de la Ataxia Telangiectasia Mutada/genética , Linfoma de Burkitt/genética , Linfoma de Burkitt/patología , Cromatina/metabolismo , Ciclina D1/genética , ADN Helicasas/genética , Proteínas de Unión al ADN/genética , Epigénesis Genética , Exoma/genética , Redes Reguladoras de Genes , Centro Germinal/metabolismo , Centro Germinal/patología , N-Metiltransferasa de Histona-Lisina/genética , Histonas/genética , Histonas/metabolismo , Humanos , Linfoma de Células del Manto/patología , Metilación , Proteínas de Neoplasias/genética , Proteínas Nucleares/genética , Proteínas Represoras/genética , Proteína de Retinoblastoma/genética , Análisis de Secuencia de ADN , Complejo Shelterina , Proteínas de Unión a Telómeros/genética , Factores de Transcripción/genética , Proteína p53 Supresora de Tumor/genéticaRESUMEN
Epstein-Barr virus (EBV) infection is a common feature of B cell lymphoproliferative disorders (LPDs), including diffuse large B cell lymphoma. Approximately 10 % of DLBCLs are EBV-positive, with the highest incidence in immunocompromised and elderly patients. Here, we review the clinical, genetic, and pathologic characteristics of DLBCL and discuss the molecular role of EBV in lymphoma tumorigenesis. Using EBV-positive DLBCL of the elderly as a model, we describe the key features of EBV-positive DLBCL. Studies of EBV-positive DLBCL of the elderly demonstrate that EBV-positive DLBCL has a distinct biology, related to both viral and host factors. The pathogenic mechanisms noted in EBV-positive DLBCL of the elderly, including enhanced NFκB activity, are likely to be a generalizable feature of EBV-positive DLBCL. Therefore, we review how this information might be used to target the EBV or its host response for the development of novel treatment strategies.
Asunto(s)
Infecciones por Virus de Epstein-Barr/virología , Herpesvirus Humano 4/fisiología , Linfoma de Células B Grandes Difuso/virología , Animales , Linfocitos B/inmunología , Linfocitos B/virología , Infecciones por Virus de Epstein-Barr/inmunología , Herpesvirus Humano 4/genética , Humanos , Linfoma de Células B Grandes Difuso/inmunología , Linfoma de Células B Grandes Difuso/patologíaRESUMEN
New therapies that challenge existing paradigms are needed for the treatment of cancer. We report a nanoparticle-enabled therapeutic approach to B-cell lymphoma using synthetic high density lipoprotein nanoparticles (HDL-NPs). HDL-NPs are synthesized using a gold nanoparticle template to control conjugate size and ensure a spherical shape. Like natural HDLs, biomimetic HDL-NPs target scavenger receptor type B-1, a high-affinity HDL receptor expressed by lymphoma cells. Functionally, compared with natural HDL, the gold NP template enables differential manipulation of cellular cholesterol flux in lymphoma cells, promoting cellular cholesterol efflux and limiting cholesterol delivery. This combination of scavenger receptor type B-1 binding and relative cholesterol starvation selectively induces apoptosis. HDL-NP treatment of mice bearing B-cell lymphoma xenografts selectively inhibits B-cell lymphoma growth. As such, HDL-NPs are biofunctional therapeutic agents, whose mechanism of action is enabled by the presence of a synthetic nanotemplate. HDL-NPs are active in B-cell lymphomas and potentially, other malignancies or diseases of pathologic cholesterol accumulation.
Asunto(s)
Biomimética/métodos , Lipoproteínas HDL/uso terapéutico , Linfoma de Células B/tratamiento farmacológico , Nanopartículas del Metal/uso terapéutico , Animales , Anexina A5 , Apoptosis/fisiología , Western Blotting , Fluoresceína-5-Isotiocianato , Humanos , Immunoblotting , Células Jurkat , Lipoproteínas HDL/metabolismo , Espectrometría de Masas , Ratones , Microscopía Electrónica de Transmisión , Receptores Depuradores de Clase B/metabolismoRESUMEN
Diffuse large B-cell lymphoma (DLBCL) is the most common form of lymphoma in adults. The disease exhibits a striking heterogeneity in gene expression profiles and clinical outcomes, but its genetic causes remain to be fully defined. Through whole genome and exome sequencing, we characterized the genetic diversity of DLBCL. In all, we sequenced 73 DLBCL primary tumors (34 with matched normal DNA). Separately, we sequenced the exomes of 21 DLBCL cell lines. We identified 322 DLBCL cancer genes that were recurrently mutated in primary DLBCLs. We identified recurrent mutations implicating a number of known and not previously identified genes and pathways in DLBCL including those related to chromatin modification (ARID1A and MEF2B), NF-κB (CARD11 and TNFAIP3), PI3 kinase (PIK3CD, PIK3R1, and MTOR), B-cell lineage (IRF8, POU2F2, and GNA13), and WNT signaling (WIF1). We also experimentally validated a mutation in PIK3CD, a gene not previously implicated in lymphomas. The patterns of mutation demonstrated a classic long tail distribution with substantial variation of mutated genes from patient to patient and also between published studies. Thus, our study reveals the tremendous genetic heterogeneity that underlies lymphomas and highlights the need for personalized medicine approaches to treating these patients.
Asunto(s)
Heterogeneidad Genética , Linfoma de Células B Grandes Difuso/genética , Adulto , Secuencia de Bases , Línea Celular Tumoral , Fosfatidilinositol 3-Quinasa Clase I , Análisis Mutacional de ADN , ADN de Neoplasias/genética , Exoma , Expresión Génica , Variación Genética , Humanos , Linfoma de Células B Grandes Difuso/tratamiento farmacológico , Modelos Moleculares , Datos de Secuencia Molecular , Terapia Molecular Dirigida , Mutación , Oncogenes , Fosfatidilinositol 3-Quinasas/química , Fosfatidilinositol 3-Quinasas/genética , Conformación Proteica , Proteínas Proto-Oncogénicas c-kit/genética , Receptor alfa de Factor de Crecimiento Derivado de Plaquetas/genética , Homología de Secuencia de Ácido Nucleico , Transducción de Señal/genéticaRESUMEN
BACKGROUND: Human erythrocytes are terminally differentiated, anucleate cells long thought to lack RNAs. However, previous studies have shown the persistence of many small-sized RNAs in erythrocytes. To comprehensively define the erythrocyte transcriptome, we used high-throughput sequencing to identify both short (18-24 nt) and long (>200 nt) RNAs in mature erythrocytes. RESULTS: Analysis of the short RNA transcriptome with miRDeep identified 287 known and 72 putative novel microRNAs. Unexpectedly, we also uncover an extensive repertoire of long erythrocyte RNAs that encode many proteins critical for erythrocyte differentiation and function. Additionally, the erythrocyte long RNA transcriptome is significantly enriched in the erythroid progenitor transcriptome. Joint analysis of both short and long RNAs identified several loci with co-expression of both microRNAs and long RNAs spanning microRNA precursor regions. Within the miR-144/451 locus previously implicated in erythroid development, we observed unique co-expression of several primate-specific noncoding RNAs, including a lncRNA, and miR-4732-5p/-3p. We show that miR-4732-3p targets both SMAD2 and SMAD4, two critical components of the TGF-ß pathway implicated in erythropoiesis. Furthermore, miR-4732-3p represses SMAD2/4-dependent TGF-ß signaling, thereby promoting cell proliferation during erythroid differentiation. CONCLUSIONS: Our study presents the most extensive profiling of erythrocyte RNAs to date, and describes primate-specific interactions between the key modulator miR-4732-3p and TGF-ß signaling during human erythropoiesis.
Asunto(s)
Eritrocitos/metabolismo , Perfilación de la Expresión Génica , MicroARNs/genética , ARN Largo no Codificante/genética , Secuencia de Bases , Diferenciación Celular/genética , Eritrocitos/citología , Sitios Genéticos/genética , Humanos , Transducción de Señal/genética , Proteína Smad2/biosíntesis , Proteína Smad4/biosíntesis , Factor de Crecimiento Transformador beta/metabolismoRESUMEN
PURPOSE OF REVIEW: Burkitt lymphoma is an important clinical and model disease arising from B cells. Burkitt lymphoma is characterized by translocation of the c-MYC gene to an immunoglobulin enhancer region, resulting in enhanced cell proliferation and rapid tumor progression. The development of deep sequencing has widened the scope of genetic analysis to reveal the role of additional collaborating mutations in Burkitt lymphoma. In this review, we examine the role of additional genetic events that cooperate with MYC in Burkitt lymphoma pathogenesis. RECENT FINDINGS: Next-generation sequencing of Burkitt lymphoma has identified recurrent silencing mutations in ID3, a novel tumor suppressor gene. In addition, mutations in a number of genes including GNA13, TP53, and SMARCA4 occur in Burkitt lymphoma. Copy number status has implicated recurrent aberrations including gains of 1q and 18q and deletion of 19p13. Additionally, microRNA and gene expression profiling has revealed unique transcriptome signatures in Burkitt lymphoma subgroups. SUMMARY: Analysis of genetic alterations in Burkitt lymphoma has yielded a better understanding of the pathogenesis of this disease. These observations could lead to more effective strategies for the diagnosis and treatment of Burkitt lymphoma.
Asunto(s)
Linfoma de Burkitt/genética , Animales , Linfoma de Burkitt/epidemiología , Variaciones en el Número de Copia de ADN , Perfilación de la Expresión Génica , Genes myc , Secuenciación de Nucleótidos de Alto Rendimiento , Humanos , MicroARNs/genética , Mutación , Transcriptoma , Translocación GenéticaRESUMEN
Merkel cell polyomavirus (MCPyV) is a DNA virus whose pathogenic mechanisms in Merkel cell carcinoma (MCC) are still being unraveled. Emerging reports of an association between MCPyV and chronic lymphocytic lymphoma (CLL) have begun to broaden our understanding of the oncogenic mechanisms of this virus and the known association between these 2 malignancies. Herein, we report a case of MCC demonstrating a B-cell immunophenotype arising in a patient with CLL being treated with rituximab. In this context, we discuss the differential diagnostic considerations, especially with cutaneous Richter transformation (diffuse large B-cell lymphoma). We also assessed for the presence of MCPyV in both the patient's MCC and the CLL. Finally, we provide a large meta-analysis of patients with CLL and MCC. Patients with both MCC and CLL have a dismal prognosis, with greater than 50% overall mortality within the first year and a half after MCC diagnosis.
Asunto(s)
Linfocitos B/patología , Carcinoma de Células de Merkel/patología , Leucemia Linfocítica Crónica de Células B/patología , Neoplasias Primarias Múltiples/patología , Neoplasias Cutáneas/patología , Anciano , Anticuerpos Monoclonales de Origen Murino/administración & dosificación , Protocolos de Quimioterapia Combinada Antineoplásica/uso terapéutico , Carcinoma de Células de Merkel/virología , Ciclofosfamida/administración & dosificación , Diagnóstico Diferencial , Resultado Fatal , Humanos , Inmunofenotipificación , Leucemia Linfocítica Crónica de Células B/tratamiento farmacológico , Masculino , Poliomavirus de Células de Merkel , Neoplasias Primarias Múltiples/virología , Infecciones por Polyomavirus/patología , Rituximab , Neoplasias Cutáneas/virología , Infecciones Tumorales por Virus/patología , Vidarabina/administración & dosificación , Vidarabina/análogos & derivadosRESUMEN
To elucidate the mechanisms underlying chromosomal translocations in diffuse large B cell lymphoma (DLBCL), we investigated the nature and extent of immunoglobulin class switch recombination (CSR) in these tumors. We used Southern blotting to detect legitimate and illegitimate CSR events in tumor samples of the activated B cell-like (ABC), germinal center B cell-like (GCB), and primary mediastinal B cell lymphoma (PMBL) subgroups of DLBCL. The frequency of legitimate CSR was lower in ABC DLBCL than in GCB DLBCL and PMBL. In contrast, ABC DLBCL had a higher frequency of internal deletions within the switch mu (Smu) region compared with GCB DLBCL and PMBL. ABC DLBCLs also had frequent deletions within Sgamma and other illegitimate switch recombinations. Sequence analysis revealed ongoing Smu deletions within ABC DLBCL tumor clones, which were accompanied by ongoing duplications and activation-induced cytidine deaminase-dependent somatic mutations. Unexpectedly, short fragments derived from multiple chromosomes were interspersed within Smu in one case. These findings suggest that ABC DLBCLs have abnormalities in the regulation of CSR that could predispose to chromosomal translocations. Accordingly, aberrant switch recombination was responsible for translocations in ABC DLBCLs involving BCL6, MYC, and a novel translocation partner, SPIB.
Asunto(s)
Cambio de Clase de Inmunoglobulina/inmunología , Activación de Linfocitos/genética , Linfoma de Células B/inmunología , Linfoma de Células B Grandes Difuso/inmunología , Recombinación Genética , Translocación Genética , Línea Celular Tumoral , Humanos , Cambio de Clase de Inmunoglobulina/genética , Linfoma de Células B/genética , Linfoma de Células B de la Zona Marginal/genética , Linfoma de Células B de la Zona Marginal/inmunología , Linfoma de Células B Grandes Difuso/genética , Células Tumorales CultivadasRESUMEN
Epstein-Barr virus (EBV) is an oncogenic human herpesvirus that dramatically reorganizes host gene expression to immortalize primary B cells. In this study, we analyzed EBV-regulated host gene expression changes following primary B-cell infection, both during initial proliferation and through transformation into lymphoblastoid cell lines (LCLs). While most EBV-regulated mRNAs were changed during the transition from resting, uninfected B cells through initial B-cell proliferation, a substantial number of mRNAs changed uniquely from early proliferation through LCL outgrowth. We identified constitutively and dynamically EBV-regulated biological processes, protein classes, and targets of specific transcription factors. Early after infection, genes associated with proliferation, stress responses, and the p53 pathway were highly enriched. However, the transition from early to long-term outgrowth was characterized by genes involved in the inhibition of apoptosis, the actin cytoskeleton, and NF-κB activity. It was previously thought that the major viral protein responsible for NF-κB activation, latent membrane protein 1 (LMP1), is expressed within 2 days after infection. Our data indicate that while this is true, LCL-level LMP1 expression and NF-κB activity are not evident until 3 weeks after primary B-cell infection. Furthermore, heterologous NF-κB activation during the first week after infection increased the transformation efficiency, while early NF-κB inhibition had no effect on transformation. Rather, inhibition of NF-κB was not toxic to EBV-infected cells until LMP1 levels and NF-κB activity were high. These data collectively highlight the dynamic nature of EBV-regulated host gene expression and support the notion that early EBV-infected proliferating B cells have a fundamentally distinct growth and survival phenotype from that of LCLs.
Asunto(s)
Linfocitos B/citología , Linfocitos B/virología , Transformación Celular Viral/genética , Herpesvirus Humano 4/metabolismo , FN-kappa B/metabolismo , Proteínas de la Matriz Viral/metabolismo , Citoesqueleto de Actina/genética , Apoptosis/genética , Proliferación Celular , Células Cultivadas , Regulación de la Expresión Génica , Herpesvirus Humano 4/genética , Herpesvirus Humano 4/crecimiento & desarrollo , Humanos , FN-kappa B/antagonistas & inhibidores , FN-kappa B/genética , ARN Mensajero/genética , ARN Mensajero/metabolismo , ARN Viral/genética , Proteína p53 Supresora de Tumor/genética , Proteínas de la Matriz Viral/biosíntesis , Replicación Viral/genéticaRESUMEN
Epstein-Barr virus (EBV) infection of primary human B cells drives their indefinite proliferation into lymphoblastoid cell lines (LCLs). B cell immortalization depends on expression of viral latency genes, as well as the regulation of host genes. Given the important role of microRNAs (miRNAs) in regulating fundamental cellular processes, in this study, we assayed changes in host miRNA expression during primary B cell infection by EBV. We observed and validated dynamic changes in several miRNAs from early proliferation through immortalization; oncogenic miRNAs were induced, and tumor suppressor miRNAs were largely repressed. However, one miRNA described as a p53-targeted tumor suppressor, miR-34a, was strongly induced by EBV infection and expressed in many EBV and Kaposi's sarcoma-associated herpesvirus (KSHV)-infected lymphoma cell lines. EBV latent membrane protein 1 (LMP1) was sufficient to induce miR-34a requiring downstream NF-κB activation but independent of functional p53. Furthermore, overexpression of miR-34a was not toxic in several B lymphoma cell lines, and inhibition of miR-34a impaired the growth of EBV-transformed cells. This study identifies a progrowth role for a tumor-suppressive miRNA in oncogenic-virus-mediated transformation, highlighting the importance of studying miRNA function in different cellular contexts.