RESUMO
Similar to classical Hodgkin lymphoma (HL) tumour cells, primary effusion lymphoma (PEL) originates from mature B cells but displays a non-B cell phenotype, the mechanisms and consequences of which are not yet understood. This study showed that PEL lacked DNA binding activity of the B cell-determining transcription factors E2A, EBF and Pax5. PEL overexpressed the E2A antagonists ABF-1 and Id2, which have been described to block the B-cell differentiation program in classical HL. However, in contrast to HL cells, B lineage-inappropriate genes were not similarly upregulated in PEL, and reconstitution of B cell-specific E2A homodimer activity in PEL induced apoptosis. These data demonstrate that lineage infidelity in PEL is not as pronounced as in HL, and that the loss of the B cell-specific transcription factor E2A in PEL is implicated in apoptosis protection.
Assuntos
Fatores de Transcrição Hélice-Alça-Hélice Básicos/genética , Genes Supressores de Tumor , Linfoma/genética , Apoptose , Linfócitos B/metabolismo , Linfócitos B/patologia , Fatores de Transcrição Hélice-Alça-Hélice Básicos/metabolismo , Northern Blotting , Diferenciação Celular , Linhagem Celular , Células Cultivadas , DNA/metabolismo , Proteínas de Ligação a DNA/genética , Proteínas de Ligação a DNA/metabolismo , Ensaio de Desvio de Mobilidade Eletroforética , Deleção de Genes , Humanos , Linfoma/patologia , Fator de Transcrição PAX5/genética , Fator de Transcrição PAX5/metabolismo , Linfócitos T/metabolismo , Linfócitos T/patologia , Transativadores/genética , Transativadores/metabolismo , TransfecçãoRESUMO
The proteasome inhibitor bortezomib has been used successfully in the treatment of non-Hodgkin lymphomas in humans, and in the treatment of graft versus host disease (GVHD) and autoimmune diseases in animal models. The mechanism of growth inhibition and immunosuppression is only partly understood. Here, we have evaluated the differential effect of bortezomib on human monocyte derived immature and mature dendritic cells (DCs) as the maturation stage of DCs determines their function. We found bortezomib to induce apoptotic cell death in immature DCs and to a much lesser extent, in mature DCs. Furthermore, cytokine-induced maturation of immature DCs was inhibited by bortezomib, whereas already matured DCs remained unaffected as seen by phenotype and allo-stimulatory capacity. This corresponded to a decreased NF-kappaB activity in immature DCs, whereas NF-kappaB activity of mature DCs was not affected. In conclusion, our data expand on previous reports on the effects of proteasome inhibitors on human monocyte-derived DCs by demonstrating a differential effect of bortezomib on immature versus mature DCs. Our findings suggest a potential role of bortezomib in modulating immune responses in humans through inhibition of DC maturation.
Assuntos
Apresentação de Antígeno/efeitos dos fármacos , Ácidos Borônicos/farmacologia , Células Dendríticas/efeitos dos fármacos , Inibidores de Proteases/farmacologia , Complexo de Endopeptidases do Proteassoma/efeitos dos fármacos , Pirazinas/farmacologia , Adulto , Antígenos CD/análise , Apoptose/efeitos dos fármacos , Bortezomib , Diferenciação Celular/efeitos dos fármacos , Células Cultivadas/citologia , Células Cultivadas/efeitos dos fármacos , Células Cultivadas/enzimologia , Células Dendríticas/citologia , Células Dendríticas/enzimologia , Ensaio de Desvio de Mobilidade Eletroforética , Fator Estimulador de Colônias de Granulócitos e Macrófagos/farmacologia , Humanos , Imunofenotipagem , Interleucina-4/farmacologia , Teste de Cultura Mista de Linfócitos , Monócitos/citologia , NF-kappa B/metabolismoRESUMO
B cell differentiation is controlled by a complex network of lineage-restricted transcription factors. How perturbations to this network alter B cell fate remains poorly understood. Here we show that classical Hodgkin lymphoma tumor cells, which originate from mature B cells, have lost the B cell phenotype as a result of aberrant expression of transcriptional regulators. The B cell-specific transcription factor program was disrupted by overexpression of the helix-loop-helix proteins ABF-1 and Id2. Both factors antagonized the function of the B cell-determining transcription factor E2A. As a result, expression of genes specific to B cells was lost and expression of genes not normally associated with the B lineage was upregulated. These data demonstrate the plasticity of mature human lymphoid cells and offer an explanation for the unique classical Hodgkin lymphoma phenotype.
Assuntos
Linfócitos B/metabolismo , Fatores de Transcrição Hélice-Alça-Hélice Básicos/antagonistas & inibidores , Fatores de Transcrição Hélice-Alça-Hélice Básicos/metabolismo , Doença de Hodgkin/metabolismo , Proteína 2 Inibidora de Diferenciação/metabolismo , Linfócitos B/imunologia , Linfócitos B/patologia , Sequência de Bases , Fatores de Transcrição Hélice-Alça-Hélice Básicos/genética , Linhagem Celular Tumoral , Dimerização , Expressão Gênica , Doença de Hodgkin/genética , Doença de Hodgkin/imunologia , Doença de Hodgkin/patologia , Humanos , Proteína 2 Inibidora de Diferenciação/genética , Complexos Multiproteicos , Fator de Transcrição PAX5/genética , Fator de Transcrição PAX5/metabolismo , Fenótipo , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , RNA Neoplásico/genética , RNA Neoplásico/metabolismoRESUMO
Transcription factor nuclear factor kappa B (NF-kappaB) plays a central role in the pathogenesis of classical Hodgkin lymphoma (cHL). In anaplastic large-cell lymphomas (ALCLs), which share molecular lesions with cHL, the NF-kappaB system has not been equivalently investigated. Here we describe constitutive NF-kappaB p50 homodimer [(p50)2] activity in ALCL cells in the absence of constitutive activation of the IkappaB kinase (IKK) complex. Furthermore, (p50)2 contributes to the NF-kappaB activity in Hodgkin/Reed-Sternberg (HRS) cells. Bcl-3, which is an inducer of nuclear (p50)2 and is associated with (p50)2 in ALCL and HRS cell lines, is abundantly expressed in ALCL and HRS cells. Notably, a selective overexpression of Bcl-3 target genes is found in ALCL cells. By immunohistochemical screening of 288 lymphoma cases, a strong Bcl-3 expression in cHL and in peripheral T-cell non-Hodgkin lymphoma (T-NHL) including ALCL was found. In 3 of 6 HRS cell lines and 25% of primary ALCL, a copy number increase of the BCL3 gene locus was identified. Together, these data suggest that elevated Bcl-3 expression has an important function in cHL and peripheral T-NHL, in particular ALCL.
Assuntos
Regulação Neoplásica da Expressão Gênica , Doença de Hodgkin/genética , Doença de Hodgkin/metabolismo , Linfoma de Células T Periférico/genética , Linfoma de Células T Periférico/metabolismo , Subunidade p50 de NF-kappa B/metabolismo , Proteínas Proto-Oncogênicas/metabolismo , Proteína 3 do Linfoma de Células B , Linhagem Celular , Dimerização , Humanos , Proteínas I-kappa B/metabolismo , Interleucina-9/metabolismo , Linfoma de Células T Periférico/patologia , Análise em Microsséries , Proteínas Oncogênicas v-rel/metabolismo , Ligação Proteica , Proteínas Proto-Oncogênicas/genética , Fatores de TranscriçãoRESUMO
The immunosuppressive macrolide rapamycin and its derivative everolimus (SDZ RAD, RAD) inhibit the mammalian target of rapamycin (mTOR) signaling pathway. In this study, we provide evidence that RAD has profound antiproliferative activity in vitro and in NOD/SCID mice in vivo against Hodgkin lymphoma (HL) and anaplastic large cell lymphoma (ALCL) cells. Moreover, we identified 2 molecular mechanisms that showed how RAD exerts antiproliferative effects in HL and ALCL cells. RAD down-regulated the truncated isoform of the transcription factor CCAAT enhancer binding protein beta (C/EBPbeta), which is known to disrupt terminal differentiation and induce a transformed phenotype. Furthermore, RAD inhibited constitutive nuclear factor kappaB (NF-kappaB) activity, which is a critical survival factor of HL cells. Pharmacologic inhibition of the mTOR pathway by RAD therefore interferes with essential proliferation and survival pathways in HL and ALCL cells and might serve as a novel treatment option.
Assuntos
Proteína beta Intensificadora de Ligação a CCAAT/metabolismo , Proliferação de Células/efeitos dos fármacos , Doença de Hodgkin/metabolismo , Linfoma Difuso de Grandes Células B/metabolismo , NF-kappa B/metabolismo , Sirolimo/análogos & derivados , Animais , Proteína beta Intensificadora de Ligação a CCAAT/efeitos dos fármacos , Ciclo Celular/efeitos dos fármacos , Ciclo Celular/fisiologia , Linhagem Celular Tumoral , Regulação para Baixo/efeitos dos fármacos , Everolimo , Humanos , Camundongos , Camundongos Endogâmicos NOD , Camundongos SCID , NF-kappa B/efeitos dos fármacos , Sirolimo/farmacologia , Transplante HeterólogoRESUMO
Resistance to death receptor-mediated apoptosis is supposed to be important for the deregulated growth of B cell lymphoma. Hodgkin/Reed-Sternberg (HRS) cells, the malignant cells of classical Hodgkin's lymphoma (cHL), resist CD95-induced apoptosis. Therefore, we analyzed death receptor signaling, in particular the CD95 pathway, in these cells. High level CD95 expression allowed a rapid formation of the death-inducing signaling complex (DISC) containing Fas-associated death domain-containing protein (FADD), caspase-8, caspase-10, and most importantly, cellular FADD-like interleukin 1beta-converting enzyme-inhibitory protein (c-FLIP). The immunohistochemical analysis of the DISC members revealed a strong expression of CD95 and c-FLIP overexpression in 55 out of 59 cases of cHL. FADD overexpression was detectable in several cases. Triggering of the CD95 pathway in HRS cells is indicated by the presence of CD95L in cells surrounding them as well as confocal microscopy showing c-FLIP predominantly localized at the cell membrane. Elevated c-FLIP expression in HRS cells depends on nuclear factor (NF)-kappaB. Despite expression of other NF-kappaB-dependent antiapoptotic proteins, the selective down-regulation of c-FLIP by small interfering RNA oligoribonucleotides was sufficient to sensitize HRS cells to CD95 and tumor necrosis factor-related apoptosis-inducing ligand-induced apoptosis. Therefore, c-FLIP is a key regulator of death receptor resistance in HRS cells.
Assuntos
Proteínas Adaptadoras de Transdução de Sinal , Apoptose/fisiologia , Proteínas de Transporte/fisiologia , Doença de Hodgkin/patologia , Doença de Hodgkin/fisiopatologia , Peptídeos e Proteínas de Sinalização Intracelular , Células de Reed-Sternberg/patologia , Células de Reed-Sternberg/fisiologia , Receptor fas/fisiologia , Apoptose/efeitos dos fármacos , Proteínas Reguladoras de Apoptose , Sequência de Bases , Proteína Reguladora de Apoptosis Semelhante a CASP8 e FADD , Proteínas de Transporte/genética , Proteínas de Transporte/metabolismo , Caspase 10 , Caspase 8 , Caspases/metabolismo , Linhagem Celular Tumoral , Cicloeximida/farmacologia , Proteína de Domínio de Morte Associada a Fas , Humanos , Glicoproteínas de Membrana/fisiologia , NF-kappa B/metabolismo , RNA Interferente Pequeno/genética , Células de Reed-Sternberg/efeitos dos fármacos , Ligante Indutor de Apoptose Relacionado a TNF , Fator de Necrose Tumoral alfa/fisiologiaRESUMO
Arsenic can induce apoptosis and is an efficient drug for the treatment of acute promyelocytic leukemia. Currently, clinical studies are investigating arsenic as a therapeutic agent for a variety of malignancies. In this study, Hodgkin/Reed-Sternberg (HRS) cell lines served as model systems to characterize the role of nuclear factor-kappaB (NF-kappaB) in arsenic-induced apoptosis. Arsenic rapidly down-regulated constitutive IkappaB kinase (IKK) as well as NF-kappaB activity and induced apoptosis in HRS cell lines containing functional IkappaB proteins. In these cell lines, apoptosis was blocked by inhibition of caspase-8 and caspase-3-like activity. Furthermore, arsenic treatment down-regulated NF-kappaB target genes, including tumor necrosis factor-alphareceptor-associated factor 1 (TRAF1), c-IAP2, interleukin-13 (IL-13), and CCR7. In contrast, cell lines with mutated, functionally inactive IkappaB proteins or with a weak constitutive IKK/NF-kappaB activity showed no alteration of the NF-kappaB activity and were resistant to arsenic-induced apoptosis. A direct role of the NF-kappaB pathway in arsenic-induced apoptosis is shown by transient overexpression of NF-kappaB-p65 in L540Cy HRS cells, which protected the cells from arsenic-induced apoptosis. In addition, treatment of NOD/SCID mice with arsenic trioxide induced a dramatic reduction of xenotransplanted L540Cy Hodgkin tumors concomitant with NF-kappaB inhibition. We conclude that inhibition of NF-kappaB contributes to arsenic-induced apoptosis. Furthermore, pharmacologic inhibition of the IKK/NF-kappaB activity might be a powerful treatment option for Hodgkin lymphoma.
Assuntos
Apoptose/efeitos dos fármacos , Arsênio/farmacologia , NF-kappa B/antagonistas & inibidores , Células de Reed-Sternberg/patologia , Animais , Trióxido de Arsênio , Arsenicais/farmacologia , Arsenitos/farmacologia , Regulação para Baixo , Perfilação da Expressão Gênica , Doença de Hodgkin/metabolismo , Doença de Hodgkin/patologia , Humanos , Quinase I-kappa B , Camundongos , Camundongos SCID , Óxidos/farmacologia , Proteínas Serina-Treonina Quinases/antagonistas & inibidores , Células de Reed-Sternberg/efeitos dos fármacos , Compostos de Sódio/farmacologia , Transplante Heterólogo , Células Tumorais CultivadasRESUMO
AP-1 family transcription factors have been implicated in the control of proliferation, apoptosis and malignant transformation. However, their role in oncogenesis is unclear and no recurrent alterations of AP-1 activities have been described in human cancers. Here, we show that constitutively activated AP-1 with robust c-Jun and JunB overexpression is found in all tumor cells of patients with classical Hodgkin's disease. A similar AP-1 activation is present in anaplastic large cell lymphoma (ALCL), but is absent in other lymphoma types. Whereas c-Jun is up-regulated by an autoregulatory process, JunB is under control of NF-kappa B. Activated AP-1 supports proliferation of Hodgkin cells, while it suppresses apoptosis of ALCL cells. Furthermore, AP-1 cooperates with NF-kappa B and stimulates expression of the cell-cycle regulator cyclin D2, proto-oncogene c-met and the lymphocyte homing receptor CCR7, which are all strongly expressed in primary HRS cells. Together, these data suggest an important role of AP-1 in lymphoma pathogenesis.