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1.
Cancer Treat Rev ; 126: 102735, 2024 May.
Artigo em Inglês | MEDLINE | ID: mdl-38613871

RESUMO

Since colon cancer has a high rate of shedding of tumour fragments into the blood, several research efforts are now focused on the investigation of the minimal residual disease through the detection of ctDNA to tailor the adjuvant therapy of colon cancer patients and optimize its cost/effectiveness balance. The negative prognostic impact of detectable ctDNA in patients' blood after radical surgery for colon cancer is well established. Several clinical trials adopting heterogeneous designs and techniques are now ongoing to translate promises into daily practice by answering five general questions: i) is a ctDNA-guided decision making efficacious in the post-operative management of colon cancer patients? ii) are de-escalation strategies possible in ctDNA-negative cases? iii) are escalation strategies useful to improve the prognosis of ctDNA-positive patients? iv) when MRD is identified at the end of the adjuvant chemotherapy, is another post-adjuvant systemic therapy efficacious? v) can we exploit ctDNA technologies in the follow up of colon cancer patients? This review focuses on currently ongoing trials and how their results may affect the ctDNA "liquid revolution" of early colon cancer.


Assuntos
DNA Tumoral Circulante , Neoplasias do Colo , Humanos , Neoplasias do Colo/tratamento farmacológico , Quimioterapia Adjuvante/métodos , DNA Tumoral Circulante/sangue , Prognóstico , Ensaios Clínicos como Assunto , Biomarcadores Tumorais/genética , Neoplasia Residual
2.
Sci Rep ; 13(1): 1378, 2023 01 25.
Artigo em Inglês | MEDLINE | ID: mdl-36697438

RESUMO

Targeted therapy significantly impairs tumour growth but suffers from limitations, among which the 'flare' ('rebound') effect. Among cancers driven by tyrosine kinase receptors, those relying on alterations of the MET oncogene benefit from treatment by specific inhibitors. Previously, we reported that discontinuation of MET tyrosine kinase receptor inhibition causes 'rebound' activation of the oncogene, with a post-treatment transient hyperphosphorylation phase that culminates into a dramatic increase in cancer cell proliferation. The molecular mechanisms behind the 'MET burst' after treatment cessation are unknown but critically important for patients. Here we identify a positive feedback loop mediated by the AKT/mTOR pathway leading to (a) enhanced MET translation by activating p70S6K and 4EBP1 and (b) MET hyper-phosphorylation by inactivation of the tyrosine-phosphatase PTP1B. The latter effect is due to m-TOR-driven PTP1B phosphorylation of the inhibitory residues Ser50 and Ser378. These data provide in vitro evidence for the use of mTOR inhibitors to prevent the 'flare effect' in MET targeted therapy, with potential applicative ramifications for patient clinical management.


Assuntos
Neoplasias , Proteínas Proto-Oncogênicas c-akt , Proteínas Proto-Oncogênicas c-met , Serina-Treonina Quinases TOR , Humanos , Linhagem Celular Tumoral , Neoplasias/tratamento farmacológico , Fosforilação , Proteínas Proto-Oncogênicas c-akt/metabolismo , Proteínas Proto-Oncogênicas c-met/antagonistas & inibidores , Serina-Treonina Quinases TOR/metabolismo , Retroalimentação Fisiológica
3.
Oncogene ; 32(11): 1428-40, 2013 Mar 14.
Artigo em Inglês | MEDLINE | ID: mdl-22562252

RESUMO

Basal-like breast cancer is an aggressive subtype of mammary carcinoma. Despite expressing basal markers, typical of mammary stem cells, this tumor has been proposed to originate from luminal progenitors, which are downstream of stem cells along the mammary epithelial hierarchy. This suggests that committed luminal progenitors may reacquire basal, stem-like characteristics, but the mechanisms that regulate this transition remain unclear. Using mouse models, we found that luminal progenitors express high levels of the Met receptor for hepatocyte growth factor (HGF), as compared with the other mammary epithelial sub-populations. Constitutive activation of Met led luminal progenitors to attain stem cell properties, including enhanced clonogenic activity in vitro and de novo ability to reconstitute mammary glands in repopulation assays in vivo. Moreover, in response to Met signaling, luminal progenitors gave rise to hyperplastic ductal morphogenesis and preferentially underwent basal lineage commitment at the expense of luminal cell-fate specification. Opposite and symmetric results were produced by systemic pharmacological inhibition of Met. Hence, Met signaling targets luminal progenitors for expansion, impairs their differentiation toward the mature luminal phenotype and enables their commitment toward the basal lineage. These results emphasize a critical role for Met in promoting deregulated proliferation and basal plasticity of normal luminal progenitors in the mammary gland, a complex of events that may be required for sustaining the functional and phenotypic properties of basal-like breast tumors.


Assuntos
Neoplasias da Mama/patologia , Diferenciação Celular/genética , Proliferação de Células , Células Epiteliais/fisiologia , Glândulas Mamárias Animais/fisiologia , Neoplasia de Células Basais/patologia , Proteínas Proto-Oncogênicas c-met/fisiologia , Animais , Neoplasias da Mama/genética , Linhagem da Célula/genética , Células Cultivadas , Células Epiteliais/metabolismo , Feminino , Glândulas Mamárias Animais/citologia , Glândulas Mamárias Animais/metabolismo , Neoplasias Mamárias Experimentais/genética , Neoplasias Mamárias Experimentais/patologia , Camundongos , Neoplasia de Células Basais/genética , Fenótipo , Proteínas Proto-Oncogênicas c-met/genética , Proteínas Proto-Oncogênicas c-met/metabolismo , Transdução de Sinais/genética , Células-Tronco/metabolismo , Células-Tronco/fisiologia
4.
Oncogene ; 28(11): 1421-31, 2009 Mar 19.
Artigo em Inglês | MEDLINE | ID: mdl-19151767

RESUMO

Basal-like breast cancers (BLBCs) are aggressive tumors with high relapse rates and poor survival. We recently reported that >70% of primary BLBCs express the oncogenic transcription/translation factor Y-box binding protein-1 (YB-1) and silencing it with small interfering RNAs (siRNAs) attenuates the growth of BLBC cell lines. To understand the basis of these earlier findings, we profiled YB-1:DNA complexes by chromatin immunoprecipitation (ChIP)-on-chip. Several tumor growth-promoting genes such as MET, CD44, CD49f, WNT and NOTCH family members were identified. In addition, YB-1 and MET are coordinately expressed in BLBC cell lines, as well as in normal human mammary progenitor cells. MET was confirmed to be a YB-1 target through traditional ChIP and gel-shift assays. More specifically, YB-1 binds to -1018 bp on the MET promoter. Silencing YB-1 with siRNA decreased MET promoter activity, transcripts, as well as protein levels and signaling. Conversely, expressing wild-type YB-1 or a constitutively active mutant YB-1 (D102) increased MET expression. Finally, silencing YB-1 or MET attenuated anchorage-independent growth of BLBC cell lines. Together, these findings implicate MET as a target of YB-1 that work in concert to promote BLBC growth.


Assuntos
Neoplasias da Mama/patologia , Mama/química , Proteínas de Ligação a DNA/fisiologia , Proteínas Nucleares/fisiologia , Proteínas Proto-Oncogênicas/fisiologia , Receptores de Fatores de Crescimento/fisiologia , Neoplasias da Mama/química , Linhagem Celular Tumoral , Imunoprecipitação da Cromatina , Proteínas de Ligação a DNA/análise , Proteínas de Ligação a DNA/genética , Ensaio de Desvio de Mobilidade Eletroforética , Feminino , Perfilação da Expressão Gênica , Fator de Crescimento de Hepatócito/farmacologia , Humanos , Proteínas Nucleares/análise , Proteínas Nucleares/genética , Regiões Promotoras Genéticas , Proteínas Proto-Oncogênicas/análise , Proteínas Proto-Oncogênicas/genética , Proteínas Proto-Oncogênicas c-met , RNA Interferente Pequeno/genética , Receptores de Fatores de Crescimento/análise , Receptores de Fatores de Crescimento/genética , Células-Tronco/química , Proteína 1 de Ligação a Y-Box
5.
Eur J Histochem ; 51 Suppl 1: 79-92, 2007.
Artigo em Inglês | MEDLINE | ID: mdl-17703598

RESUMO

Branching morphogenesis is a multi-step process that controls the formation of polarised tubules starting from hollow cysts. Its execution entails a series of rate-limiting events which include reversible disruption of cell polarity, dismantling of intercellular contacts, acquisition of a motile phenotype, stimulation of cell proliferation, and final re-establishment of cell polarity for creation of the definitive structures. Branching morphogenesis takes place physiologically during development, accounting for the establishment of organs endowed with a ramified architecture such as glands, the respiratory tract and the vasculartree. In cancer, aberrant implementation of branching morphogenesis leads to deregulated proliferation, protection from apoptosis and enhanced migratory/invasive properties, which together exacerbate the aggressive features of neoplastic cells. Under both physiological and pathological conditions, branching morphogenesis is mainly accomplished by a family of growth factors known as scatter factors. In this review, we will summarise the current knowledge on the biological and functional roles of scatter factors during branching morphogenesis, with a special emphasis on the phenotypic (structural and histological) consequences of scatter factor activity in different tissues.


Assuntos
Transformação Celular Neoplásica , Fator de Crescimento de Hepatócito/metabolismo , Morfogênese , Animais , Humanos , Transdução de Sinais
6.
Transfus Clin Biol ; 14(3): 327-33, 2007 Aug.
Artigo em Francês | MEDLINE | ID: mdl-17462938

RESUMO

ABO incompatibility is not a barrier for allogeneic hematopoietic stem cell transplantation but is associated with specific complications. Major ABO incompatibility is associated with delayed erythroid engraftment, increased transfusion requirement and cases of pure red cell aplasia. Minor ABO incompatibility may be responsible for acute haemolytic reactions in the first months following transplantation. The widely used non myeloablative conditioning regimens might modify the management of ABO incompatibility. They could favour pure red cell aplasia development in the setting of major ABO mismatch since they are associated with a prolonged persistence of host anti-donor isohemagglutinins after allogeneic hematopoietic stem cell transplantation. In the setting of minor ABO incompatibility, the use of peripheral blood stem cells and the nature of graft-versus-host disease prophylaxis regimen may have an impact on the incidence of haemolytic reactions. In that review, the clinical and therapeutic aspects of ABO incompatibility are studied, especially regarding the impact of the conditioning regimen intensity.


Assuntos
Sistema ABO de Grupos Sanguíneos/imunologia , Incompatibilidade de Grupos Sanguíneos , Transplante de Células-Tronco , Transplante Homólogo/imunologia , Humanos , Terapia de Imunossupressão/métodos , Imunossupressores/uso terapêutico
7.
Vox Sang ; 92(1): 85-9, 2007 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-17181595

RESUMO

BACKGROUND AND OBJECTIVES: In the setting of major ABO-incompatible allogeneic haematopoietic stem cell transplantation (HSCT), pure red cell aplasia (PRCA) is linked to the persistence of host residual plasma cells secreting antidonor isohaemagglutinins (HA) after transplantation. There are conflicting results regarding the impact of the intensity of conditioning regimen on the occurrence of PRCA after major ABO-mismatched HSCT. MATERIAL AND METHODS: To address this question, we compared two cases occurring after nonmyeloablative (NMA) and myeloablative (MA) HSCT and reviewed previous cases reported in the NMA setting. RESULTS AND CONCLUSIONS: We observed a delayed disappearance of antidonor HAs in the NMA setting, associated to a more prolonged period of red blood cells transfusion dependence than in the MA setting. In our case as in several others, the disappearance of antidonor HAs and resolution of PRCA were observed after reinforcement of the graft-versus-host effect (i.e. immunosuppression removal or donor leukocytes infusion).


Assuntos
Sistema ABO de Grupos Sanguíneos/efeitos adversos , Transplante de Células-Tronco Hematopoéticas/efeitos adversos , Aplasia Pura de Série Vermelha/etiologia , Condicionamento Pré-Transplante/efeitos adversos , Condicionamento Pré-Transplante/métodos , Adulto , Função Retardada do Enxerto , Feminino , Doença Enxerto-Hospedeiro , Hemaglutininas/imunologia , Humanos , Masculino , Pessoa de Meia-Idade , Transplante Homólogo/efeitos adversos
8.
Cell Mol Life Sci ; 63(9): 1024-7, 2006 May.
Artigo em Inglês | MEDLINE | ID: mdl-16612563

RESUMO

In human patients, blood coagulation disorders often associate with cancer, even in its early stages. Recently, in vitro and in vivo experimental models have shown that oncogene expression, or inactivation of tumour suppressor genes, upregulate genes that control blood coagulation. These studies suggest that activation of blood clotting, leading to peritumoral fibrin deposition, is instrumental in cancer development. Fibrin can indeed build up a provisional matrix, supporting the invasive growth of neoplastic tissues and blood vessels. Interference with blood coagulation can thus be considered as part of a multifaceted therapeutic approach to cancer.


Assuntos
Coagulação Sanguínea/genética , Regulação Neoplásica da Expressão Gênica , Modelos Genéticos , Neoplasias/genética , Animais , Ciclo-Oxigenase 2/genética , Fibrina/genética , Hemostasia/genética , Humanos , Proteínas de Membrana/genética , Neoplasias/irrigação sanguínea , Inibidor 1 de Ativador de Plasminogênio/genética
9.
Bone Marrow Transplant ; 34(12): 1089-93, 2004 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-15489877

RESUMO

To evaluate the impact of ex vivo expanded megakaryocyte (MK) progenitors on high-dose chemotherapy-induced thrombocytopenia, we conducted a phase II study in 10 patients with relapsed lymphoma. Two fractions of peripheral blood progenitor cells (PBPC) were cryopreserved, one with enough cells for at least 2 x 10(6) CD34+ cells/kg and a second obtained after CD34+ selection. Ten days before autologous stem cell transplantation, the CD34+ fraction was cultured with MGDF+SCF for 10 days. After BEAM (BCNU, cyclophosphamide, cytarabine, and melphalan) chemotherapy, patients were reinfused with standard PBPC and ex vivo expanded cells. No toxicity was observed after reinfusion. The mean fold expansion was 9.27 for nucleated cells, 2 for CD34+ cells, 676 for CD41+ cells, and 627 for CD61+ cells. The median date of platelet transfusion independence was day 8 (range: 7-12). All patients received at least one platelet transfusion. In conclusion, ex vivo expansion of MK progenitors was feasible and safe, but this procedure did not prevent BEAM-induced thrombocytopenia. Future studies will determine if expansion of higher numbers of CD34+ cells towards the MK-differentiation pathway will translate into a functional effect in terms of shortening of BEAM-induced thrombocytopenia.


Assuntos
Células Precursoras Eritroides/citologia , Megacariócitos/citologia , Transplante de Células-Tronco de Sangue Periférico/métodos , Antígenos CD34/análise , Protocolos de Quimioterapia Combinada Antineoplásica/uso terapêutico , Protocolos de Quimioterapia Combinada Antineoplásica/toxicidade , Carmustina/administração & dosagem , Técnicas de Cultura de Células/métodos , Células Cultivadas , Ciclofosfamida/administração & dosagem , Citarabina/administração & dosagem , Células Precursoras Eritroides/efeitos dos fármacos , Células Precursoras Eritroides/transplante , Humanos , Integrina beta3/análise , Linfoma/complicações , Linfoma/terapia , Megacariócitos/transplante , Melfalan/administração & dosagem , Glicoproteína IIb da Membrana de Plaquetas/análise , Transfusão de Plaquetas , Terapia de Salvação , Trombocitopenia/induzido quimicamente , Trombocitopenia/prevenção & controle , Trombopoetina/farmacologia , Transplante Autólogo , Resultado do Tratamento
10.
Hum Gene Ther ; 13(2): 243-60, 2002 Jan 20.
Artigo em Inglês | MEDLINE | ID: mdl-11812281

RESUMO

Safe and efficient genetic modification of liver cells could enable new therapies for a variety of hepatic and systemic diseases. Lentiviral vectors are promising tools for in vivo gene delivery. Previous data suggested that recruitment into the cell cycle was required for transduction of hepatocytes in vivo. We developed an improved vector design that enhanced nuclear translocation in target cells and significantly improved gene transfer performance. Using the new vector and a panel of internal promoters, we showed that rat hepatocytes were transduced ex vivo to high frequency without requirement for proliferation. On intravenous administration of vector into adult severe combined immunodeficient (SCID) mice, we found high levels (up to 30%) of transduction of parenchymal and nonparenchymal cells of the liver, integration of the vector genome in liver DNA and stable expression of the marker green fluorescent protein (GFP)-encoding gene without signs of toxicity. Coadministration of vectors and 5'-bromo-2'-deoxyuridine in vivo proved that cell cycling was not required for efficient transduction of hepatocytes. In addition to the liver, the spleen and the bone marrow were transduced effectively by systemic delivery of vector. GFP expression was observed in all these organs when driven by the cytomegalovirus promoter and by the phosphoglycerate kinase gene promoter. Using the promoter of the albumin gene, we could restrict expression to hepatocytes. By a single vector injection into the bloodstream of SCID mice, we achieved therapeutic-range levels of the human clotting factor IX, stable in the plasma for up to 1 year (the longest time tested), indicating the potential efficacy of improved lentiviral vectors for the gene therapy of hemophilias and other diseases.


Assuntos
Vetores Genéticos , Hepatócitos , Lentivirus/genética , Regiões Promotoras Genéticas , Transdução Genética , Animais , Fator IX/genética , Feminino , Expressão Gênica , Genes pol , Terapia Genética/métodos , Células HeLa , Fator de Crescimento de Hepatócito , Humanos , Camundongos , Camundongos SCID , Ratos , Transgenes
11.
Virology ; 286(1): 225-36, 2001 Jul 20.
Artigo em Inglês | MEDLINE | ID: mdl-11448175

RESUMO

Dendritic cells (DCs) are thought to play a crucial role in the pathogenesis of HIV-1 infection. DCs are believed to transport virus particles to lymph nodes before transfer to CD4(+) lymphocytes. We have investigated the role of Nef in these processes. HIV-1 replication was examined in human immature DC-lymphocyte cocultures and in DCs or lymphocytes separately. Using various R5-tropic and X4-tropic HIV-1 strains and their nef-deleted (Deltanef) counterparts, we show that Nef is required for optimal viral replication in immature DC-T cells clusters and in T lymphocytes. Nef exerts only a marginal role on viral replication in immature DCs alone as well as on virion capture by DCs, long-term intracellular accumulation and transmission of X4 strains to lymphocytes. We also show that wild-type and Deltanef virions are similarly processed for MHC-I restricted exogenous presentation by DCs. Taken together, these results help explain how HIV-1 Nef may affect viral spread and immune responses in the infected host.


Assuntos
Células Dendríticas/virologia , Produtos do Gene nef/fisiologia , Infecções por HIV/virologia , HIV-1/fisiologia , Linfócitos/virologia , Comunicação Celular , Células Cultivadas , Técnicas de Cocultura , Células Dendríticas/patologia , Infecções por HIV/patologia , Humanos , Linfócitos/patologia , Replicação Viral , Produtos do Gene nef do Vírus da Imunodeficiência Humana
12.
Semin Cancer Biol ; 11(2): 153-65, 2001 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-11322834

RESUMO

Scatter factors are unequivocal signals governing a genetic program that includes cell detachment, repulsion, protection from apoptosis, invasiveness of extracellular matrices and proliferation. This pleiomorphic response is defined as 'invasive growth'. Under physiological conditions, it leads to morphogenic cell movements through the matrix, and--primarily--to ordered building of epithelial tubules. Dysfunctions in invasive growth cause enhanced proliferation, uncontrolled migration into surrounding tissues, and failure to differentiate, events that foster tumour growth and invasiveness. Scatter factors act through tyrosine kinase receptors that belong to the Met oncogene family. Here we discuss how alterations of these receptors or of their signal transduction pathways are responsible for cancer onset and progression towards metastasis.


Assuntos
Fator de Crescimento de Hepatócito/fisiologia , Invasividade Neoplásica , Neoplasias/metabolismo , Humanos , Neoplasias/patologia , Transdução de Sinais
13.
Nat Med ; 7(3): 344-9, 2001 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-11231634

RESUMO

Dendritic cells and macrophages can process extracellular antigens for presentation by MHC-I molecules. This exogenous pathway may have a crucial role in the activation of CD8+ cytotoxic T lymphocytes during human viral infections. We show here that HIV-1 epitopes derived from incoming virions are presented through the exogenous MHC-I pathway in primary human dendritic cells, and to a lower extent in macrophages, leading to cytotoxic T-lymphocyte activation in the absence of viral protein synthesis. Exogenous antigen presentation required adequate virus-receptor interactions and fusion of viral and cellular membranes. These results provide new insights into how anti-HIV cytotoxic T lymphocytes can be activated and have implications for anti-HIV vaccine design.


Assuntos
Antígenos HIV/imunologia , HIV-1/imunologia , Antígenos de Histocompatibilidade Classe I/imunologia , Vírion/imunologia , Replicação Viral , Linhagem Celular , Reações Cruzadas , Epitopos/imunologia , HIV-1/fisiologia , Humanos
14.
J Immunol ; 166(2): 1241-7, 2001 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-11145707

RESUMO

Hepatocyte growth factor (HGF) is a potent paracrine mediator of stromal/epithelial interactions, which is secreted as a matrix-associated inactive precursor (pro-HGF) and locally activated by tightly controlled urokinase cleavage. It induces proliferation and motility in epithelial and endothelial cells, and plays a role in physiological and pathological processes involving invasive cell growth, such as angiogenesis and parenchymal regeneration. We now report that HGF induces directional migration and cytokine secretion in human monocytes. Monocyte activation by endotoxin and IL-1beta results in the up-regulation of the HGF receptor expression and in the induction of cell-associated pro-HGF convertase activity, thus enhancing cell responsiveness to the factor. Furthermore, we provide evidence for the secretion of biologically active HGF by activated monocytes, implying an autocrine stimulation. Altogether, these data indicate that monocyte function is modulated by HGF in a paracrine/autocrine manner, and provide a new link between stromal environment and mononuclear phagocytes.


Assuntos
Fator de Crescimento de Hepatócito/fisiologia , Macrófagos/imunologia , Monócitos/imunologia , Adesão Celular/imunologia , Células Cultivadas , Quimiotaxia de Leucócito/imunologia , Meios de Cultura/metabolismo , Fator Estimulador de Colônias de Granulócitos/biossíntese , Fator Estimulador de Colônias de Granulócitos/genética , Fator Estimulador de Colônias de Granulócitos e Macrófagos/biossíntese , Fator Estimulador de Colônias de Granulócitos e Macrófagos/genética , Fator de Crescimento de Hepatócito/biossíntese , Fator de Crescimento de Hepatócito/genética , Fator de Crescimento de Hepatócito/metabolismo , Humanos , Interleucina-6/biossíntese , Interleucina-6/genética , Ativação de Macrófagos/imunologia , Macrófagos/metabolismo , Monócitos/metabolismo , Fator de Ativação de Plaquetas/farmacologia , Precursores de Proteínas/metabolismo , Proteínas Proto-Oncogênicas c-met/biossíntese , Proteínas Proto-Oncogênicas c-met/sangue , RNA Mensageiro/biossíntese , Proteínas Recombinantes/farmacologia , Transcrição Gênica/imunologia
15.
J Immunol ; 166(1): 81-8, 2001 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-11123279

RESUMO

The HIV-1 nef gene, essential for AIDS pathogenesis, encodes a 27-kDa protein (Nef) whose biochemical and biological functions are unclear. It has been suggested that Nef expression contributes to the T cell depletion observed during the disease by promoting their apoptosis. We report that in CD4(+) human lymphoblastoid cell lines transfected with the nef cDNA obtained from three different HIV-1 strains, expression of the Nef protein enhances and accelerates the response to four unrelated apoptotic agents (staurosporine, anisomycin, camptothecin, and etoposide) but not to an anti-Fas agonist Ab. Nef reduces the expression of the anti-apoptotic proteins Bcl-2 and Bcl-X(L) and induces a striking enhancement of apoptotic hallmarks, including mitochondrial depolarization, exposure of phosphatidylserine on the cell surface, activation of caspase-3, and cleavage of the caspase target poly(ADP-ribose) polymerase. Interestingly, the peptide Z-Val-Ala-DL-Asp-fluoromethylketone (a broad-spectrum caspase inhibitor) reduces, but does not abolish, phosphatidylserine exposure, suggesting that Nef also activates a caspase-independent apoptotic pathway. Surprisingly, Nef expression increases DNA degradation but without causing oligonucleosomal fragmentation. An increased apoptotic response and down-modulation of Bcl-2/Bcl-X(L) following Nef expression are observed also in NIH-3T3 fibroblasts. These data show that Nef enhances programmed cell death in different cell types by affecting multiple critical components of the apoptotic machinery independently from the Fas pathway.


Assuntos
Adjuvantes Imunológicos/fisiologia , Apoptose/imunologia , Produtos do Gene nef/fisiologia , HIV-1/imunologia , Células 3T3 , Animais , Caspase 3 , Caspases/metabolismo , Fragmentação do DNA/imunologia , Ativação Enzimática/imunologia , Humanos , Membranas Intracelulares/metabolismo , Potenciais da Membrana/imunologia , Camundongos , Mitocôndrias/metabolismo , Fosfatidilserinas/metabolismo , Proteínas Proto-Oncogênicas c-bcl-2/antagonistas & inibidores , Proteínas Proto-Oncogênicas c-bcl-2/biossíntese , Linfócitos T/enzimologia , Linfócitos T/metabolismo , Linfócitos T/patologia , Células Tumorais Cultivadas , Proteína bcl-X , Produtos do Gene nef do Vírus da Imunodeficiência Humana
16.
Biosci Rep ; 21(6): 839-55, 2001 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-12166831

RESUMO

Knowing that human blood monocyte-derived dendritic cells express cell-surface mannose-specific lectins, we prepared various mannoses containing glycoconjugates with the aim of developing highly specific synthetic carriers of oligonucleotides and genes. Conjugates were prepared from oligosaccharides obtained by hydrazinolysis of Saccharomyces cerevisiae invertase glycopeptides. The reducing saccharides were converted into glycosynthons, i.e., into glyco-amino acids. Fluorescein derivatives were obtained by coupling the free carboxyl group of oligosaccharyl-pyroglutamate to the alpha-amino group of epsilon-fluoresceinyl-thiocarbamyl lysine methyl ester. It has been shown by others that glycosylated linear oligolysines containing up to six alpha-D-mannopyranosylphenylthiocarbamyl units have a high affinity for the human mannose receptor. In order to obtain fully biodegradable clusters and to improve both the specificity and the selectivity, disaccharides transformed into glycosynthons were coupled to pentalysine carriers (Lys5-Ala-Cys-NH2). Glycosylated pentalysyl cysteine conjugates were made fluorescent upon substitution of the cysteine thiol group with fluorescein iodoacetamide. As shown by flow cytofluorimetry, both the dimannoside clusters and yeast oligomannosides were very efficiently taken up by DC, conversely lactoside clusters were not.


Assuntos
Células Dendríticas/metabolismo , Endocitose/fisiologia , Manosídeos/metabolismo , Transporte Biológico , Células Dendríticas/citologia , Citometria de Fluxo , Corantes Fluorescentes/metabolismo , Glicosídeo Hidrolases/metabolismo , Humanos , Manosídeos/química , Estrutura Molecular , Oligopeptídeos/metabolismo , Polissacarídeos/química , Polissacarídeos/metabolismo , Proteínas de Saccharomyces cerevisiae/metabolismo , beta-Frutofuranosidase
17.
J Virol ; 74(21): 10018-24, 2000 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-11024130

RESUMO

Human cytomegalovirus (HCMV) infection is well controlled mainly by cytotoxic CD8(+) T lymphocytes (CTL) directed against the matrix protein pp65 despite the numerous immune escape mechanisms developed by the virus. Dendritic cells (DCs) are key antigen-presenting cells for the generation of an immune response which have the capacity to acquire antigens via endocytosis of apoptotic cells and thus present peptides to major histocompatibility complex class I-restricted T cells. We examined whether this mechanism could contribute to the activation of anti-pp65 CTL. In this study, we show that infection by HCMV AD169 induced sensitization of MRC5 fibroblasts to tumor necrosis factor alpha-mediated apoptosis very early after virus inoculation and that pp65 contained in apoptotic cells came from the delivery of the matrix protein into the cell. We observed that immature DCs derived from peripheral monocytes were not permissive to HCMV AD169 infection but were able to internalize pp65-positive apoptotic infected MRC5 cells. We then demonstrated that following exposure to these apoptotic bodies, DCs could activate HLA-A2- or HLA-B35-restricted anti-pp65 CTL, suggesting that they acquired and processed properly fibroblast-derived pp65. Together, our data suggest that cross-presentation of incoming pp65 contained in apoptotic cells may provide a quick and efficient way to prime anti-HCMV CD8(+) T cells.


Assuntos
Apresentação de Antígeno , Citomegalovirus/imunologia , Células Dendríticas/imunologia , Fibroblastos/virologia , Fosfoproteínas/imunologia , Linfócitos T Citotóxicos/imunologia , Proteínas da Matriz Viral/imunologia , Células Apresentadoras de Antígenos , Apoptose , Linhagem Celular , Humanos , Ativação Linfocitária , Fator de Necrose Tumoral alfa/farmacologia
18.
FASEB J ; 14(11): 1629-40, 2000 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-10928998

RESUMO

Hepatocyte growth factor/scatter factor (HGF/SF) controls a genetic program known as 'invasive growth', which involves as critical steps cell adhesion, migration, and trespassing of basement membranes. We show here that in MDA-MB-231 carcinoma cells, these steps are elicited by HGF/SF but not by epidermal growth factor (EGF). Neither factor substantially alters the production or activity of extracellular matrix proteases. HGF/SF, but not EGF, selectively promotes cell adhesion on laminins 1 and 5, fibronectin, and vitronectin through a PI3-K-dependent mechanism. Increased adhesion is followed by enhanced invasiveness through isolated matrix proteins as well as through reconstituted basement membranes. Inhibition assays using function-blocking antibodies show that this phenomenon is mediated by multiple integrins including beta1, beta3, beta4, and beta5. HGF/SF triggers clustering of all these integrins at actin-rich adhesive sites and lamellipodia but does not quantitatively modify their membrane expression. These data suggest that HGF/SF promotes cell adhesion and invasiveness by increasing the avidity of integrins for their specific ligands.


Assuntos
Neoplasias da Mama/metabolismo , Neoplasias da Mama/patologia , Movimento Celular/efeitos dos fármacos , Fator de Crescimento de Hepatócito/farmacologia , Integrinas/metabolismo , Actinas/efeitos dos fármacos , Actinas/metabolismo , Anticorpos/imunologia , Anticorpos/farmacologia , Membrana Basal/química , Membrana Basal/metabolismo , Neoplasias da Mama/enzimologia , Caderinas/metabolismo , Adesão Celular/efeitos dos fármacos , Divisão Celular/efeitos dos fármacos , Colágeno/metabolismo , Citoesqueleto/efeitos dos fármacos , Citoesqueleto/metabolismo , Relação Dose-Resposta a Droga , Combinação de Medicamentos , Fator de Crescimento Epidérmico/farmacologia , Proteínas da Matriz Extracelular/metabolismo , Expressão Gênica/efeitos dos fármacos , Humanos , Integrinas/antagonistas & inibidores , Integrinas/imunologia , Laminina/metabolismo , Ligantes , Metaloproteinase 9 da Matriz/metabolismo , Invasividade Neoplásica/patologia , Fenótipo , Fosfatidilinositol 3-Quinases/metabolismo , Inibidores de Fosfoinositídeo-3 Quinase , Proteoglicanas/metabolismo , Células Tumorais Cultivadas , Ativador de Plasminogênio Tipo Uroquinase/metabolismo
19.
Exp Cell Res ; 253(1): 88-99, 1999 Nov 25.
Artigo em Inglês | MEDLINE | ID: mdl-10579914

RESUMO

Plasminogen-related growth factors (PRGFs), also known as "scatter factors," trigger a unique biological program leading to "invasive growth." This is a result of the integration of apparently independent biological responses including cell proliferation, cell survival, cell motility, invasion of extracellular matrices, and induction of cell polarity. Under physiological conditions, the coordinated execution of the underlying genetic programs leads to the formation of tubular structures by epithelial organs (the so-called branching morphogenesis). PRGF receptors are tyrosine kinases, encoded by a family of oncogenes: MET and RON. They feature unique signal transduction properties as their cytoplasmic tails contain a two-tyrosine multifunctional docking site that binds multiple SH2-containing intracellular signal transducers. Invasive growth results from the concomitant activation of Ras (growth), phosphatidylinositol 3-kinase ("scattering"), and signal transducer and activator of transcription (cell polarity and morphogenesis). We recently identified a new human gene family, encoding large transmembrane proteins, sex/plexins, sharing homologies with Met. These molecules are receptors for semaphorins, involved in axon guidance and cell-cell repulsion, a process reminiscent of scattering and invasive growth. Deregulated activation of PRGF or semaphorin ligands or receptors, by mutation or overexpression, confers to cancer cells invasive and metastatic properties.


Assuntos
Transformação Celular Neoplásica , Morfogênese , Família Multigênica , Receptores Proteína Tirosina Quinases/metabolismo , Receptores de Superfície Celular/metabolismo , Proteínas Oncogênicas/genética , Proteínas Oncogênicas/metabolismo , Proteínas Proto-Oncogênicas c-met/genética , Proteínas Proto-Oncogênicas c-met/metabolismo , Receptores Proteína Tirosina Quinases/genética , Receptores de Superfície Celular/classificação , Receptores de Superfície Celular/genética , Receptores de Fator de Crescimento Neural/genética , Receptores de Fator de Crescimento Neural/metabolismo , Transdução de Sinais
20.
Presse Med ; 28(31): 1709-16, 1999 Oct 16.
Artigo em Francês | MEDLINE | ID: mdl-10554614

RESUMO

CD34 SORTING: CD34 sorting is a means of selecting hematopoietic stem cells among heterogeneous populations of cells. The technique is based on the fact that only hematopoietic stem cells (excepting a few tumoral cells) carry the CD34 antigen. Generally this type of manipulation is performed in case of stem cell grafts or for the treatment of certain malignant hematological diseases or certain solid tumors. OBJECTIVES: For autologous grafts, CD34 sorting reduces the number of tumoral cells contained in the graft and thus limits the risk of induced relapse. For allografts, CD34 sorting reduces the number of reinjected T cells, and thus the risk of severe, often life-threatening, graft-versus-host disease. TECHNIQUES AND BIOLOGICAL RESULTS: Five techniques have been developed using anti-CD34 antibodies. Currently, the most widely used techniques rely on immunomagnetic methods where the antibody is bound to a magnetic bead (Baxter, Miltenyi). The Systemix technique (high-flow cytometry) can only be applied in industrial settings. In all cases, there is at least a 2 log reduction in the number of tumoral cells and T cells with a more or less pronounced loss of CD34 cells (maximal loss 50%). CLINICAL RESULTS: No randomized study has been reported for CDR-sorted autografts in comparison with non-sorted grafts, but several authors have published results showing an advantage in terms of overall survival and disease-free survival. For allografts, only a few studies have been reported to date. CD34 sorting appears to lower the rate of graft-versus-host disease if sufficient T-cell depletion is achieved. OTHER ASPECTS: CD34 sorting is also used in other types of cell manipulations: cell expansion, gene transfer, production of dendritic cells for immunotherapy.


Assuntos
Antígenos CD34/imunologia , Transplante Autólogo/imunologia , Transplante Heterólogo/imunologia , Transplante Homólogo/imunologia , Humanos
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