RESUMO
Chronic lymphocytic leukemia (CLL) clones are characterized by loss of a critical region in 13q14.3, (del(13)(q14)) involving the microRNA (miRNA) cluster miR-15a and miR-16-1. We have investigated the effects of replacement of miR-15a and miR-16-1. CLL cells transfected with these miRNA mimics exhibited a decrease in cell viability in vitro and impaired capacity for engraftment and growth in NOD/Shi-scid,γcnull (NSG) mice. No synergistic effects were observed when the two miRNA mimics were combined. The phenomena were not restricted to CLL with the del(13)(q14) lesion. Similar effects induced by miRNA mimics were seen in cells with additional chromosomal abnormalities with the exception of certain CLL clones harboring TP53 alterations. Administration of miRNA mimics to NSG mice previously engrafted with CLL clones resulted in substantial tumor regression. CLL cell transfection with miR-15a and miR-16-1-specific inhibitors resulted in increased cell viability in vitro and in an enhanced capacity of the engrafted cells to grow in NSG mice generating larger splenic nodules. These data demonstrate that the strong control by miR-15a and miR-16-1 on CLL clonal expansion is exerted also at the level of full-blown leukemia and provide indications for a miRNA-based therapeutic strategy.
Assuntos
Leucemia Linfocítica Crônica de Células B/genética , MicroRNAs/farmacologia , Animais , Linhagem Celular , Proliferação de Células/efeitos dos fármacos , Sobrevivência Celular/efeitos dos fármacos , Deleção Cromossômica , Cromossomos Humanos Par 13 , Xenoenxertos , Humanos , Leucemia Linfocítica Crônica de Células B/etiologia , Leucemia Linfocítica Crônica de Células B/patologia , Camundongos , MicroRNAs/genética , Transfecção , Carga Tumoral/efeitos dos fármacosAssuntos
Receptor com Domínio Discoidina 1/genética , Expressão Gênica , Leucemia Linfocítica Crônica de Células B/genética , Leucemia Linfocítica Crônica de Células B/patologia , Biomarcadores Tumorais , Receptor com Domínio Discoidina 1/metabolismo , Progressão da Doença , Humanos , Leucemia Linfocítica Crônica de Células B/mortalidade , Leucemia Linfocítica Crônica de Células B/terapia , PrognósticoAssuntos
Biomarcadores Tumorais/análise , Leucemia Linfocítica Crônica de Células B/mortalidade , Adulto , Idoso , Estudos de Coortes , Intervalo Livre de Doença , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Estudos Multicêntricos como Assunto , Estudos Observacionais como Assunto , Prognóstico , Modelos de Riscos Proporcionais , Fatores de RiscoRESUMO
Interleukin (IL)-31A binds to an heterodimer composed of IL-31 receptor A (IL-31RA) and Oncostatin M Receptor (OSMR). The IL-31/IL-31R complex is involved in the pathogenesis of various skin diseases, including cutaneous T-cell lymphoma. No information is available on the relations between the IL-31/IL-31R complex and B-cell lymphoma. Here we have addressed this issue in follicular lymphoma (FL), a prototypic germinal center(GC)-derived B-cell malignancy. IL-31 enhanced primary FL cell proliferation through IL-31R-driven signal transducer and activator of transcription factor 1/3 (STAT1/3), extracellular signal-regulated kinase 1/2 (ERK1/2) and Akt phosphorylation. In contrast, GC B cells did not signal to IL-31 in spite of IL-31R expression. GC B cells expressed predominantly the inhibitory short IL-31RA isoform, whereas FL cells expressed predominantly the long signaling isoform. Moreover, GC B cells lacked expression of other IL-31RA isoforms potentially involved in the signaling pathway. IL-31 protein expression was significantly higher in surface membrane than in cytosol of both FL and GC B cells. IL-31 was detected in plasma membrane microvesicles from both cell types but not released in soluble form in culture supernatants. IL-31 and IL-31RA expression was higher in lymph nodes from FL patients with grade IIIa compared with grade I/II, suggesting a paracrine and/or autocrine role of IL-31/IL-31RA complex in tumor progression through microvesicle shedding.
Assuntos
Linfócitos B/metabolismo , Regulação Leucêmica da Expressão Gênica , Centro Germinativo/metabolismo , Interleucinas/genética , Linfoma Folicular/genética , Receptores de Interleucina/genética , Linfócitos B/patologia , Membrana Celular/metabolismo , Proliferação de Células , Micropartículas Derivadas de Células/metabolismo , Citosol/metabolismo , Feminino , Centro Germinativo/patologia , Humanos , Interleucinas/metabolismo , Linfoma Folicular/metabolismo , Linfoma Folicular/patologia , Masculino , Pessoa de Meia-Idade , Proteína Quinase 1 Ativada por Mitógeno/genética , Proteína Quinase 1 Ativada por Mitógeno/metabolismo , Proteína Quinase 3 Ativada por Mitógeno/genética , Proteína Quinase 3 Ativada por Mitógeno/metabolismo , Gradação de Tumores , Fosforilação , Cultura Primária de Células , Isoformas de Proteínas/genética , Isoformas de Proteínas/metabolismo , Proteínas Proto-Oncogênicas c-akt/genética , Proteínas Proto-Oncogênicas c-akt/metabolismo , Receptores de Interleucina/metabolismo , Fator de Transcrição STAT1/genética , Fator de Transcrição STAT1/metabolismo , Fator de Transcrição STAT3/genética , Fator de Transcrição STAT3/metabolismo , Transdução de SinaisRESUMO
BACKGROUND: Uveal melanoma is the most frequent primary tumour of the eye. It is molecularly clearly distinct from cutaneous melanoma and shows a different pattern of driver mutations. The influence of sunlight ultraviolet (UV) exposure on the aetiology of uveal melanoma is a matter of debate. The recent identification of driver mutations in the promoter of the telomerase reverse transcriptase (TERT) gene with UV-induced cytidine-to-thymidine transitions in cutaneous melanoma prompted us to investigate whether these mutations also occur in uveal melanoma. METHODS: We analysed 50 cases of uveal melanoma obtained from enucleation surgery for mutations in the genes GNAQ, GNA11, BAP1, SF3B1, EIFAX1 and TERT, measured gene expression using microarrays and analysed gene copy numbers by SNP arrays. RESULTS: We detected a TERT mutation in only one case of a 57-year-old white male patient with clinical and histopathological features typical for uveal melanoma. The tumour showed mutations in GNA11 and EIF1AX that are typical for uveal melanoma and absent from cutaneous melanoma. No mutations were detected in GNAQ, BAP1 and SF3B1 that are frequently mutated in uveal melanoma. Both copies of chromosome 3 were retained. Several tumours among which the one carrying the TERT promoter mutation showed elevated TERT expression. Consistent with previous reports, GNAQ is inversely associated with chromosome 3 monosomy and metastasis. BAP1 mutations are significantly associated with chromosome 3 monosomy but not with relapse. CONCLUSION: These data indicate that TERT mutations are rare in uveal melanoma. No conclusion can be drawn on their potential influence on tumour progression.
Assuntos
Melanoma/genética , Telomerase/genética , Neoplasias Uveais/genética , Cromossomos Humanos Par 3/genética , Fator de Iniciação 1 em Eucariotos/genética , Subunidades alfa de Proteínas de Ligação ao GTP/genética , Subunidades alfa Gq-G11 de Proteínas de Ligação ao GTP , Humanos , Masculino , Metaloendopeptidases/genética , Pessoa de Meia-Idade , Mutação , Fosfoproteínas/genética , Regiões Promotoras Genéticas , Fatores de Processamento de RNA , Ribonucleoproteína Nuclear Pequena U2/genética , Análise de Sequência de DNARESUMO
The 2014 OECI Oncology Days was held at the 'Prof. Dr. Ion Chiricuta' Oncology Institute in Cluj, Romania, from 12 to 13 June. The focus of this year's gathering was on developments in personalised medicine and other treatment advances which have made the cost of cancer care too high for many regions throughout Europe.
RESUMO
Interleukin (IL)-23 and IL-27 are pro-inflammatory cytokines that share functional and structural similarities and may exert anti-tumor activities against solid and hematological malignancies. Here, we asked whether IL-23 and IL-27, alone or in combination, may act directly against human follicular lymphoma (FL) and diffuse large B-cell lymphoma (DLBCL) cells. In this study, we demonstrated for the first time that human primary FL and DLBCL cells expressed complete and functional IL-23 and IL-27 receptors (R) and that IL-23 and IL-27 exerted anti-tumor activities in vitro and in vivo through different and complementary mechanisms. In vivo studies using severe combined immunodeficiency /non-obese diabetic mice-injected subcutaneously with human SU-DHL-4 cell line revealed that IL-23 inhibited directly tumor-cell proliferation, whereas IL-27 impaired the angiogenic program of lymphoma cells resulting in strong reduction of cell growth. In addition, combined treatment of IL-23 and IL-27 amplified the anti-tumor effects in vivo as compared with administration of each cytokine alone. These anti-tumor mechanisms were confirmed by in vitro experiments performed with primary lymphoma cells and cell lines. Our results strongly encourage the development of future clinical trials to evaluate the toxicity and efficacy of the IL-23 and IL-27 in lymphoma patients.
Assuntos
Interleucina-17/uso terapêutico , Interleucina-23/uso terapêutico , Linfoma Folicular/prevenção & controle , Linfoma Difuso de Grandes Células B/prevenção & controle , Idoso , Idoso de 80 Anos ou mais , Proteínas Angiogênicas/genética , Proteínas Angiogênicas/metabolismo , Animais , Apoptose , Western Blotting , Proliferação de Células , Galinhas , Membrana Corioalantoide , DNA de Neoplasias/genética , Sinergismo Farmacológico , Feminino , Citometria de Fluxo , Humanos , Técnicas Imunoenzimáticas , Linfoma Folicular/metabolismo , Linfoma Folicular/patologia , Linfoma Difuso de Grandes Células B/metabolismo , Linfoma Difuso de Grandes Células B/patologia , Masculino , Camundongos , Camundongos Endogâmicos NOD , Camundongos SCID , Pessoa de Meia-Idade , Reação em Cadeia da Polimerase , RNA Mensageiro/genética , Reação em Cadeia da Polimerase em Tempo Real , Células Tumorais CultivadasRESUMO
Several chemokines/chemokine receptors such as CCR7, CXCR4 and CXCR5 attract chronic lymphocytic leukemia (CLL) cells to specific microenvironments. Here we have investigated whether the CX(3)CR1/CX(3)CL1 axis is involved in the interaction of CLL with their microenvironment. CLL cells from 52 patients expressed surface CX(3)CR1 and CX(3)CL1 and released constitutively soluble CX(3)CL1. One third of these were attracted in vitro by soluble CX(3)CL1. CX(3)CL1-induced phosphorylation of PI3K, Erk1/2, p38, Akt and Src was involved in induction of CLL chemotaxis. Leukemic B cells upregulated CXCR4 upon incubation with CX(3)CL1 and this was paralleled by increased chemotaxis to CXCL12. Akt phosphorylation was involved in CX(3)CL1-induced upregulation of CXCR4 on CLL. In proliferation centers from CLL lymph node and bone marrow, CX(3)CL1 was expressed by CLL cells whereas CX(3)CR1 was detected in CLL and stromal cells. Nurselike cells (NLCs) generated from CLL patient blood co-expressed surface CX(3)CR1 and CX(3)CL1, but did not secrete soluble CX(3)CL1. Only half of NLC cell fractions were attracted in vitro by CX(3)CL1. In conclusion, the CX(3)CR1/CX(3)CL1 system may contribute to interactions between CLL cells and tumor microenvironment by increasing CXCL12-mediated attraction of leukemic cells to NLC and promoting directly adhesion of CLL cells to NLC.
Assuntos
Comunicação Celular , Quimiocina CX3CL1/fisiologia , Leucemia Linfocítica Crônica de Células B/patologia , Receptores de Quimiocinas/fisiologia , Microambiente Tumoral , Adulto , Idoso , Idoso de 80 Anos ou mais , Antígenos CD/análise , Antígenos de Diferenciação Mielomonocítica/análise , Receptor 1 de Quimiocina CX3C , Quimiotaxia , Feminino , Humanos , Leucemia Linfocítica Crônica de Células B/imunologia , Linfonodos/metabolismo , Masculino , Pessoa de Meia-Idade , Fosforilação , Proteínas Proto-Oncogênicas c-akt/metabolismo , Transdução de SinaisRESUMO
Although lymphoma involvement of the gallbladder, especially by MALT and large-cell types, is rare, this possibility should be considered in patients with symptoms of acute cholecystitis. A cholecystectomy was performed in a 79-year-old male patient with a clinical diagnosis of chronic cholecystitis. Histologically, the specimen showed an incidental finding of a small lymphocytic lymphoma (CLL) by morphologic and immunophenotyping studies, subsequently confirmed with flow cytometric analysis of blood. During follow-up, multiple lymph node enlargement was detected. An axillary node, excised and submitted to our department, was positive for lymphoma involvement. The bone marrow was negative.
Assuntos
Colecistite/patologia , Neoplasias da Vesícula Biliar/patologia , Achados Incidentais , Leucemia Linfocítica Crônica de Células B/patologia , Linfoma de Células B/patologia , Idoso , Antígenos CD/metabolismo , Biomarcadores Tumorais/metabolismo , Colecistite/complicações , Colecistite/cirurgia , Doença Crônica , Neoplasias da Vesícula Biliar/metabolismo , Neoplasias da Vesícula Biliar/cirurgia , Humanos , Imunofenotipagem , Leucemia Linfocítica Crônica de Células B/metabolismo , Leucemia Linfocítica Crônica de Células B/cirurgia , Linfonodos/patologia , Linfoma de Células B/metabolismo , Linfoma de Células B/cirurgia , Masculino , Neoplasias Primárias MúltiplasRESUMO
In the present study, we demonstrate that elevated levels of the progesterone receptor (PR)-B isoform in breast cancer cells induces down-regulation of estrogen receptor (ER) alpha mRNA and protein content, causing concomitant repression of the estrogen-regulated genes insulin receptor substrate 1, cyclin D1, and pS2, addressing a specific effect of PR/PR-B on ERalpha gene transcription. ERalpha gene promoter activity was drastically inhibited by PR-B overexpression. Promoter analysis revealed a transcriptionally responsive region containing a half-progesterone response element (PRE) site located at -1757 bp to -1752 bp. Mutation of the half-PRE down-regulated the effect induced by PR/PR-B overexpression. Moreover chromatin immunoprecipitation analyses revealed an increase of PR bound to the ERalpha-regulatory region encompassing the half-PRE site, and the recruitment of a corepressor complex containing nuclear receptor corepressor (NCoR) but not silencing mediator of retinoid and thyroid hormone receptor and DAX1, concomitantly with hypoacetylation of histone H4 and displacement of RNA polymerase II. Furthermore, NCoR ablation studies demonstrated the crucial involvement of NCoR in the down-regulatory effects due to PR-B overexpression on ERalpha protein and mRNA. We also demonstrated that the ERalpha regulation observed in MCF-7 cells depended on PR-B expression because PR-B knockdown partially abrogates the feedback inhibition of ERalpha levels after estrogenic stimulus. Our study provides evidence for a mechanism by which overexpressed PR-B is able to actively repress ERalpha gene expression.
Assuntos
Receptor alfa de Estrogênio/genética , Progesterona/metabolismo , Regiões Promotoras Genéticas , Receptores de Progesterona/metabolismo , Elementos de Resposta , Neoplasias da Mama/genética , Neoplasias da Mama/metabolismo , Linhagem Celular Tumoral , Feminino , Humanos , Mutagênese Sítio-Dirigida , Proteínas Nucleares/genética , Proteínas Nucleares/metabolismo , Correpressor 1 de Receptor Nuclear , Isoformas de Proteínas/genética , Isoformas de Proteínas/metabolismo , Receptores de Progesterona/genética , Proteínas Repressoras/genética , Proteínas Repressoras/metabolismo , Transcrição GênicaRESUMO
BACKGROUND: Roughly 40% of germinal mutations in melanoma families (MF) affect p16(INK4a) and p14(ARF). We investigated the association between INK4/ARF alterations and the occurrence of pancreatic cancer in MF and in sporadic pancreatic cancer (SPC) patients. PATIENTS AND METHODS: Forty-nine MF, 66 SPC cases and 54 controls were enrolled. The INK4/ARF locus was screened. RESULTS: As compared with the general population, the risk of pancreatic cancer (PC) was increased 9.4-fold [95% confidence interval (CI) 2.7-33.4] and 2.2-fold (95% CI 0.8-5.7) in G101W-positive and -negative MF, respectively, while mean ages at onset were 61 and 77 years, respectively. A 1.7 (95% CI 1.06-2.79) increased risk of cancer at any site was observed among first-degree relatives of SPC cases as compared with controls. The G101W founder mutation was detected in 4% of SPC cases but the rate increased to 13% when tumor clustering in either branch of families was taken into account. One G101W-positive PC patient with a melanoma in a first-degree relative harbored a germline deletion of the second allele, including exon 1B. CONCLUSIONS: The presence of a deletion including exon 1B in two PC patients points to the involvement of p14(ARF) in the development of PC and may suggest that the increased risk of PC in MF is caused by impairment of both loci.
Assuntos
Adenocarcinoma/genética , Genes p16 , Mutação em Linhagem Germinativa , Neoplasias Pancreáticas/genética , Proteína Supressora de Tumor p14ARF/genética , Adenocarcinoma/epidemiologia , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Análise Mutacional de DNA , Feminino , Predisposição Genética para Doença , Heterozigoto , Humanos , Incidência , Masculino , Melanoma/epidemiologia , Melanoma/genética , Melanoma/fisiopatologia , Pessoa de Meia-Idade , Dados de Sequência Molecular , Neoplasias Pancreáticas/epidemiologia , Linhagem , Reação em Cadeia da PolimeraseAssuntos
Linfoma de Células B/diagnóstico , Leucemia-Linfoma Linfoblástico de Células Precursoras/diagnóstico , Neoplasias Cutâneas/diagnóstico , Transportadores de Cassetes de Ligação de ATP/genética , Feminino , Genes de Imunoglobulinas , Humanos , Imunofenotipagem , Lactente , Linfoma de Células B/patologia , Linfoma de Células B/terapia , Invasividade Neoplásica , Leucemia-Linfoma Linfoblástico de Células Precursoras/patologia , Leucemia-Linfoma Linfoblástico de Células Precursoras/terapia , Indução de Remissão , Neoplasias Cutâneas/patologia , Neoplasias Cutâneas/terapiaRESUMO
Human tonsillar subepithelial B cells, which are a marginal zone-equivalent B cell subset, respond readily to T-independent type 2 antigens, but not to polyclonal B cell activators in vitro. In this study, subepithelial (SE) B cells were induced to proliferate and mature into plasma cells when co-cultured with activated T cells. The response of SE B cells was not observed when co-cultures were carried out in transwell chambers or in the presence of blocking anti-LFA-1 antibodies, demonstrating the need for a close T-B cell interaction. The presence of soluble CD40 also prevented the B cell response in vitro suggesting a pivotal role of CD40-CD40 ligand interactions. The data are discussed in terms of the T cell dependence of marginal zone (MZ) B cell response and the possible existence of various MZ B cell subsets.
Assuntos
Linfócitos B/imunologia , Ativação Linfocitária , Cooperação Linfocítica , Tonsila Palatina/imunologia , Linfócitos T/imunologia , Antígenos CD40/imunologia , Células Cultivadas , Epitélio/imunologia , Humanos , Imunoglobulinas/biossíntese , Antígeno-1 Associado à Função Linfocitária/imunologiaRESUMO
The VH4 genes expressed by both resting and in vivo-activated subepithelial (SE) B cells from human tonsils were studied. Resting SE B cells were subdivided according to the presence (IgDlow) or absence (IgM-only) of surface IgD. CD27 was abundant on activated SE B cells and low on resting IgM-only B cells. Resting IgDlow SE B cells could be subdivided into CD27low and CD27high cell fractions. Resting IgDlow SE B cells displayed VH4 genes with a substantial number of mutations (13/29 of the molecular clones were mutated), whereas 25/26 of the clones from resting IgM-only SE B cells were unmutated. Moreover, mutated VH4 genes were detected mainly within the CD27high cell fraction of the IgDlow SE B cells. Several identical unmutated VH4DJH sequences (11/32) were found in different molecular clones from resting IgM-only SE B cells, suggesting local cellular expansion. Both unmutated (14/25) and mutated (11/25) sequences were found in mu transcripts of activated SE B cells. Extensive mutation was observed in the gamma transcripts of activated SE B cells. Therefore, SE B cells are heterogeneous, being comprised of B cells with mutated Ig VH4 genes, that are Ag-experienced B cells, and a subset of B cells with unmutated VH4 genes that are either virgin cells or cells driven by Ags that did not induce or select for V gene mutations.
Assuntos
Subpopulações de Linfócitos B/citologia , Subpopulações de Linfócitos B/imunologia , Tonsila Palatina/citologia , Tonsila Palatina/imunologia , Baço/citologia , Baço/imunologia , Subpopulações de Linfócitos B/metabolismo , Criança , Pré-Escolar , Epitélio , Regulação da Expressão Gênica/imunologia , Rearranjo Gênico de Cadeia Pesada de Linfócito B , Mutação em Linhagem Germinativa/imunologia , Centro Germinativo/citologia , Centro Germinativo/imunologia , Centro Germinativo/metabolismo , Humanos , Imunoglobulina D/biossíntese , Imunoglobulina M/biossíntese , Região Variável de Imunoglobulina/biossíntese , Região Variável de Imunoglobulina/genética , Imunofenotipagem , Interfase/genética , Interfase/imunologia , Ativação Linfocitária/genética , Dados de Sequência Molecular , Tonsila Palatina/metabolismo , Baço/metabolismo , Membro 7 da Superfamília de Receptores de Fatores de Necrose Tumoral/biossínteseRESUMO
Previously, we demonstrated that B-chronic lymphocytic leukemia (B-CLL) cells could be divided into 2 groups depending on the expression of CD38 by the malignant cells. The 2 groups differed in their signal-transducing capacities initiated by cross-linking of surface IgM; only in CD38-positive cells was an efficient signal delivered, invariably resulting in cell apoptosis. In this study, we investigated the effect of surface IgD cross-linking in 10 patients with CD38-positive B-CLL. Exposure of the malignant cells to goat antihuman delta-chain antibodies (Gadelta-ab) caused [Ca(++)]i mobilization and tyrosine kinase phosphorylation in a manner not different from that observed after goat antihuman mu-chain antibody (Gamu-ab) treatment in vitro. However, Gadelta-ab-treated cells failed to undergo apoptosis and instead displayed prolonged survival in culture and differentiated into plasma cells when rIL2 was concomitantly present. Cross-linking of surface IgD failed to induce proliferation of the malignant cells in vitro. Moreover, treatment with Gadelta-ab did not prevent apoptosis of B-CLL cells induced by Gamu-ab. Collectively, these experiments demonstrated that IgM and IgD expressed by the same cell may deliver opposite signals under particular circumstances and provide some clues for the understanding of the pathophysiology of B-CLL. (Blood. 2000;95:1199-1206)
Assuntos
Antígenos de Diferenciação/sangue , Linfócitos B/imunologia , Imunoglobulina D/sangue , Imunoglobulina M/sangue , Leucemia Linfocítica Crônica de Células B/imunologia , Leucemia Linfocítica Crônica de Células B/patologia , NAD+ Nucleosidase/sangue , ADP-Ribosil Ciclase , ADP-Ribosil Ciclase 1 , Anticorpos/farmacologia , Antígenos CD/sangue , Apoptose , Linfócitos B/efeitos dos fármacos , Linfócitos B/patologia , Cálcio/sangue , Ciclo Celular , Diferenciação Celular , Reagentes de Ligações Cruzadas , Citometria de Fluxo , Humanos , Cadeias gama de Imunoglobulina/sangue , Ativação Linfocitária , Glicoproteínas de Membrana , Necrose , Fosfotirosina/sangue , Proteínas Recombinantes/farmacologia , Transdução de Sinais , Células Tumorais CultivadasRESUMO
We have previously characterized mouse H4 (mH4), a surface glycoprotein recognized by the C398.4A monoclonal antibody. We now show that C398.4A also binds its human putative homolog (hpH4). Both hpH4 and mH4 (1) are selectively expressed by activated T cells and mature thymocytes, (2) are disulfide-linked dimers of two chains (29/37 kDa in humans, 25/29 kDa in mice), whose N-deglycosylation produces a single band at 20 - 21 kDa, and (3) display a low association with CD4 and the TCR. The expression pattern of hpH4 and its biochemical features showed that it is different from other known activation molecules, and this was confirmed when analysis of the tryptic digest of the hpH4 29-kDa band by peptide mass searching using matrix-assisted laser desorption ionization mass spectrometry did not reveal any significant homology with other molecules. In normal lymphoid tissue, hpH4 is expressed by T cells located at the periphery of lymph node germinal centers and paracortical areas. In T cell neoplasia, expression of hpH4 clusters with a subset of peripheral T cell lymphomas with a large-cell component, and with cases of angioimmunoblastic T cell lymphomas. Overall, these data provide evidence for a novel T cell activation molecule that could help in the phenotypic categorization of T cell malignancies.
Assuntos
Antígenos de Diferenciação de Linfócitos T/química , Linfoma de Células T/metabolismo , Subpopulações de Linfócitos T/metabolismo , Linfócitos T/metabolismo , Timo/metabolismo , Animais , Anticorpos Monoclonais/metabolismo , Antígenos de Diferenciação de Linfócitos T/biossíntese , Antígenos de Diferenciação de Linfócitos T/imunologia , Diferenciação Celular/imunologia , Humanos , Ativação Linfocitária/imunologia , Tecido Linfoide/imunologia , Tecido Linfoide/metabolismo , Tecido Linfoide/patologia , Linfoma de Células T/imunologia , Camundongos , Especificidade de Órgãos/imunologia , Homologia de Sequência de Aminoácidos , Subpopulações de Linfócitos T/imunologia , Linfócitos T/citologia , Linfócitos T/imunologia , Timo/citologia , Timo/imunologia , Células Tumorais CultivadasRESUMO
Using immunofluorescence, RT-PCR, and Western blotting, we have demonstrated the ability of human B cells to express CD4. In each of the 10 lymphoblastoid cell lines (LCL) tested there was variable, but definite, proportion of CD4-positive B cells. Expression of CD4 was related to the cell cycle; CD4 was expressed in the G1 phase and continued at later phases of the cell cycle. CD4 was in part internalized and degraded by the LCL B cells. Surface CD4 was associated to lck and its crosslinking resulted in tyrosine phosphorylation. Additional experiments conducted on freshly prepared tonsillar B cells demonstrated that CD4 was expressed by large activated B cells, but not by small resting B cells. However, not all the activated tonsillar B cells had surface CD4 since germinal center cells were CD4-negative. Crosslinking of CD4 on LCL or on tonsillar activated B cells resulted in apoptosis in vitro, a finding that indicates the capacity of CD4 to deliver functional signals to B cells and to play a regulatory function in their physiology. Exposure of CD4 expressing B cells to gp120 under conditions that resulted in CD4 crosslinking also caused apoptosis suggesting some implications for the pathophysiology of AIDS.
Assuntos
Apoptose , Linfócitos B/fisiologia , Antígenos CD4/fisiologia , Ativação Linfocitária , Antígenos CD4/análise , Ciclo Celular , Linhagem Celular , Proteína gp120 do Envelope de HIV/fisiologia , Humanos , Proteína Tirosina Quinase p56(lck) Linfócito-Específica/análiseRESUMO
In this study, we investigated the c-myc expression by tonsillar germinal center (GC) B cells using reverse transcriptase-polymerase chain reaction, flow cytometry, Western blot and in situ immunohistochemical methods. The results obtained demonstrate elevated levels of c-myc mRNA and of Myc protein in GC B cells compared to those of the other resting or activated tonsillar B cells. Separation of GC B cells into centroblasts and centrocytes revealed that, while differing in their cell cycle status, surface marker expression and morphology, the two cell types had the same propensity to apoptosis and elevated Myc protein expression, thus reinforcing the notion of a close correlation between these two events. Based upon these observations and other considerations it is proposed that elevation of Myc proteins confers to GC B cells a particular propensity to apoptosis, while the subsequent decision between progression into the cell cycle or programmed cell death is dictated by other signals that are delivered in the GC and perhaps operate at the level of other proto-oncogenes.