RESUMO
The participation of a specific subset of B cells and how they are regulated in cancer is unclear. Here, we demonstrate that the proportion of CD5(+) relative to interleukin-6 receptor α (IL-6Rα)-expressing B cells was greatly increased in tumors. CD5(+) B cells responded to IL-6 in the absence of IL-6Rα. IL-6 directly bound to CD5, leading to activation of the transcription factor STAT3 via gp130 and its downstream kinase JAK2. STAT3 upregulated CD5 expression, thereby forming a feed-forward loop in the B cells. In mouse tumor models, CD5(+) but not CD5(-) B cells promoted tumor growth. CD5(+) B cells also showed activation of STAT3 in multiple types of human tumor tissues. Thus, our findings demonstrate a critical role of CD5(+) B cells in promoting cancer.
Assuntos
Linfócitos B/imunologia , Antígenos CD5/metabolismo , Interleucina-6/metabolismo , Melanoma Experimental/patologia , Fator de Transcrição STAT3/imunologia , Animais , Antígenos CD5/biossíntese , Linhagem Celular Tumoral , Receptor gp130 de Citocina/metabolismo , Humanos , Interleucina-6/imunologia , Janus Quinase 2/metabolismo , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Células NIH 3T3 , Ligação Proteica , Receptores de Interleucina-6/biossíntese , Receptores de Interleucina-6/genética , Receptores de Interleucina-6/imunologia , Ativação Transcricional/imunologiaRESUMO
Acute myeloid leukemia (AML) is sustained by small populations of leukemia stem cells (LSCs) that can resist available treatments and represent important barriers to cure. Although previous studies have shown increased signal transducer and activator of transcription (STAT)3 and STAT5 phosphorylation in AML leukemic blasts, the role of Janus kinase (JAK) signaling in primary AML compared with normal stem cells has not been directly evaluated. We show here that JAK/STAT signaling is increased in LSCs, particularly from high-risk AML. JAK2 inhibition using small molecule inhibitors or interference RNA reduced growth of AML LSCs while sparing normal stem cells both in vitro and in vivo. Increased JAK/STAT activity was associated with increased expression and altered signaling through growth factor receptors in AML LSCs, including receptor tyrosine kinase c-KIT and FMS-related tyrosine kinase 3 (FLT3). Inhibition of c-KIT and FLT3 expression significantly inhibited JAK/STAT signaling in AML LSCs, and JAK inhibitors effectively inhibited FLT3-mutated AML LSCs. Our results indicate that JAK/STAT signaling represents an important signaling mechanism supporting AML LSC growth and survival. These studies support continued evaluation of strategies for JAK/STAT inhibition for therapeutic targeting of AML LSCs.
Assuntos
Janus Quinase 2/metabolismo , Leucemia Mieloide Aguda/metabolismo , Células-Tronco Neoplásicas/metabolismo , Receptores de Fatores de Crescimento/metabolismo , Transdução de Sinais , Animais , Antígenos CD34/metabolismo , Proliferação de Células/efeitos dos fármacos , Sobrevivência Celular/efeitos dos fármacos , Sobrevivência Celular/genética , Modelos Animais de Doenças , Feminino , Regulação Leucêmica da Expressão Gênica , Humanos , Janus Quinase 2/antagonistas & inibidores , Janus Quinases/metabolismo , Leucemia Mieloide Aguda/genética , Leucemia Mieloide Aguda/patologia , Camundongos , Células-Tronco Neoplásicas/efeitos dos fármacos , Fenótipo , Fosforilação , Pirazóis/farmacologia , Pirimidinas/farmacologia , Interferência de RNA , Receptores de Fatores de Crescimento/genética , Fatores de Transcrição STAT/metabolismo , Fator de Transcrição STAT3/genética , Fator de Transcrição STAT3/metabolismo , Fator de Transcrição STAT5/genética , Fator de Transcrição STAT5/metabolismo , Transdução de Sinais/efeitos dos fármacos , Ensaios Antitumorais Modelo de XenoenxertoRESUMO
A number of new 3,7-disubstituted pyrazolo[3,4-c]pyridines have been designed and synthesized from suitable 2-aminopyridines. The antiproliferative activity of the derivatives was determined against the pancreatic MIA PaCa-2 and ovarian SCOV3 cancer cell-lines. IC50 values of the most promising analogue 46 lie in the submicromolar or low micromolar range. Furthermore, compound 46 shows similar inhibitory activities against DU145, A2058 and PC-3 cancer cells, blocks the cell cycle at the G0/G1 phase and induce apoptosis, as determined by the appearance of apoptotic nuclei.
Assuntos
Pirazóis/química , Piridinas/química , Apoptose/efeitos dos fármacos , Ciclo Celular/efeitos dos fármacos , Linhagem Celular Tumoral , Proliferação de Células/efeitos dos fármacos , Descoberta de Drogas , Humanos , Espectroscopia de Ressonância Magnética , Pirazóis/farmacologia , Piridinas/farmacologiaRESUMO
Drug resistance in chronic myelogenous leukemia (CML) requires the development of new CML chemotherapeutic drugs. Indirubin, a well-known mutikinase inhibitor, is the major active component of "Danggui Longhui Wan", a Chinese traditional medicine used for the treatment of CML symptoms. An in-house collection of indirubin derivatives was screened at 1 µM on wild-type and imatinib-resistant T315I mutant CML cells. Herein are reported that only 15 analogues of the natural 6-bromoindirubin displayed potent cytotoxicity in the submicromolar range. Kinase assays in vitro show that eight out of the 15 active molecules strongly inhibited both c-Src and Abl oncogenic kinases in the nanomolar range. Most importantly, these eight molecules blocked the activity of T315I mutant Abl kinase at the submicromolar level and with analogue 22 exhibiting inhibitory activity at the low nanomolar range. Docking calculations suggested that active indirubins might inhibit T315I Abl kinase through an unprecedented binding to both active and Src-like inactive conformations. Analogue 22 is the first derivative of a natural product identified as an inhibitor of wild-type and imatinib-resistant T315I mutant Abl kinases.
Assuntos
Leucemia Mielogênica Crônica BCR-ABL Positiva/tratamento farmacológico , Quinases da Família src/metabolismo , Apoptose/efeitos dos fármacos , Benzamidas/farmacologia , Proteína Tirosina Quinase CSK , Linhagem Celular Tumoral , Sobrevivência Celular/efeitos dos fármacos , Cristalografia por Raios X , Resistencia a Medicamentos Antineoplásicos/efeitos dos fármacos , Humanos , Mesilato de Imatinib/farmacologia , Indóis/química , Indóis/farmacologia , Estrutura Molecular , Piperazinas/farmacologia , Inibidores de Proteínas Quinases/química , Inibidores de Proteínas Quinases/farmacologia , Pirimidinas/farmacologiaRESUMO
Dysregulated inflammation in adipose tissue, marked by increased proinflammatory T-cell accumulation and reduced regulatory T cells (Tregs), contributes to obesity-associated insulin resistance. The molecular mechanisms underlying T-cell-mediated inflammation in adipose tissue remain largely unknown, however. Here we show a crucial role for signal transducer and activator of transcription 3 (Stat3) in T cells in skewing adaptive immunity in visceral adipose tissue (VAT), thereby contributing to diet-induced obesity (DIO) and insulin resistance. Stat3 activity is elevated in obese VAT and in VAT-resident T cells. Functional ablation of Stat3 in T cells reduces DIO, improves insulin sensitivity and glucose tolerance, and suppresses VAT inflammation. Importantly, Stat3 ablation reverses the high Th1/Treg ratio in VAT of DIO mice that is likely secondary to elevated IL-6 production, leading in turn to suppression of Tregs. In addition, Stat3 in T cells in DIO mice affects adipose tissue macrophage accumulation and M2 phenotype. Our study identifies Stat3 in VAT-resident T cells as an important mediator and direct target for regulating adipose tissue inflammation, DIO, and its associated metabolic dysfunctions.
Assuntos
Resistência à Insulina/imunologia , Gordura Intra-Abdominal/imunologia , Obesidade/imunologia , Fator de Transcrição STAT3/imunologia , Subpopulações de Linfócitos T/imunologia , Animais , Glicemia/metabolismo , Western Blotting , Dieta Hiperlipídica/efeitos adversos , Jejum/sangue , Feminino , Citometria de Fluxo , Inflamação/genética , Inflamação/imunologia , Inflamação/metabolismo , Insulina/sangue , Interferon gama/imunologia , Interferon gama/metabolismo , Interleucina-6/imunologia , Interleucina-6/metabolismo , Gordura Intra-Abdominal/metabolismo , Gordura Intra-Abdominal/patologia , Macrófagos/imunologia , Macrófagos/metabolismo , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Obesidade/sangue , Obesidade/etiologia , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Fator de Transcrição STAT3/genética , Fator de Transcrição STAT3/metabolismo , Subpopulações de Linfócitos T/metabolismo , Linfócitos T Reguladores/imunologia , Linfócitos T Reguladores/metabolismo , Células Th1/imunologia , Células Th1/metabolismoRESUMO
BACKGROUND: The EGFR signaling pathway is frequently activated in human ovarian cancer and associated with poor prognosis. However, inhibition of EGFR signaling in patients with recurrent ovarian cancer has been disappointing. It remains to be addressed whether ovarian cancer patients could benefit from targeting EGFR signaling. Here we investigated the mechanisms underlying the resistance to EGFR inhibition in ovarian cancer and developed a strategy to overcome it. RESULTS: We found that treatment of human ovarian cancer cells with an EGFR inhibitor, gefitinib, resulted in increased STAT3 phosphorylation in a dose- and time-dependent manner. Inhibiting STAT3 activation with a small molecule inhibitor of JAK, an upstream kinase that phosphorylates and activates STAT3, synergistically increased the anti-tumor activity of gefitinib in vitro. Similar results were obtained when STAT3 or JAK1 expression was knocked down. In contrast, inhibiting other signaling pathways, such as AKT/mTOR, MEK or SRC, was relatively less effective. The combined treatment resulted in simultaneous attenuation of multiple survival pathways and increased inhibition of ERK pathway. In addition, the dual inhibition showed a stronger suppression of xenograft tumor growth than either single inhibition. CONCLUSIONS: Our findings demonstrate that feedback activation of STAT3 pathway might contribute to the resistance to EGFR inhibition. Combined blockade of both pathways appears to be more effective against human ovarian cancer than inhibition of each pathway alone both in vitro and in vivo. This study may provide a strategy to improve clinical benefit of targeting EGFR pathway in ovarian cancer patients.
Assuntos
Antineoplásicos/farmacologia , Receptores ErbB/antagonistas & inibidores , Janus Quinases/antagonistas & inibidores , Neoplasias Ovarianas/enzimologia , Fator de Transcrição STAT3/antagonistas & inibidores , Transdução de Sinais/efeitos dos fármacos , Animais , Apoptose/efeitos dos fármacos , Western Blotting , Linhagem Celular Tumoral , Sobrevivência Celular/efeitos dos fármacos , Sinergismo Farmacológico , Receptores ErbB/metabolismo , Feminino , Gefitinibe , Técnicas de Silenciamento de Genes , Humanos , Janus Quinases/metabolismo , Camundongos , Neoplasias Ovarianas/patologia , Inibidores de Proteínas Quinases/farmacologia , Quinazolinas/farmacologia , Fator de Transcrição STAT3/metabolismo , Bibliotecas de Moléculas Pequenas/farmacologia , Ensaios Antitumorais Modelo de XenoenxertoRESUMO
COHCAP (City of Hope CpG Island Analysis Pipeline) is an algorithm to analyze single-nucleotide resolution DNA methylation data produced by either an Illumina methylation array or targeted bisulfite sequencing. The goal of the COHCAP algorithm is to identify CpG islands that show a consistent pattern of methylation among CpG sites. COHCAP is currently the only DNA methylation package that provides integration with gene expression data to identify a subset of CpG islands that are most likely to regulate downstream gene expression, and it can generate lists of differentially methylated CpG islands with â¼50% concordance with gene expression from both cell line data and heterogeneous patient data. For example, this article describes known breast cancer biomarkers (such as estrogen receptor) with a negative correlation between DNA methylation and gene expression. COHCAP also provides visualization for quality control metrics, regions of differential methylation and correlation between methylation and gene expression. This software is freely available at https://sourceforge.net/projects/cohcap/.
Assuntos
Algoritmos , Ilhas de CpG , Metilação de DNA , Neoplasias da Mama/genética , Linhagem Celular Tumoral , Feminino , Expressão Gênica , Genômica , Humanos , Análise de Sequência com Séries de Oligonucleotídeos , Análise de Sequência de DNA , SulfitosRESUMO
The mechanisms underlying hypermethylation of tumor-suppressor gene promoters in cancer is not well understood. Here, we report that lysine acetylation of the oncogenic transcription factor STAT3 is elevated in tumors. We also show that genetically altering STAT3 at Lys685 reduces tumor growth, which is accompanied by demethylation and reactivation of several tumor-suppressor genes. Moreover, mutating STAT3 at Lys685 disrupts DNA methyltransferase 1-STAT3 interactions in cultured tumor cells and in tumors. These observations are confirmed by treatment with an acetylation inhibitor, resveratrol. Furthermore, reduction of acetylated STAT3 in triple-negative breast cancer cells leads to demethylation and activation of the estrogen receptor-α gene, sensitizing the tumor cells to antiestrogens. Our results also demonstrate a correlation between STAT3 acetylation and methylation of estrogen receptor-α in melanoma, which predicts melanoma progression. Taken together, these results suggest a role of STAT3 acetylation in regulating CpG island methylation, which may partially explain aberrant gene silencing in cancer. These findings also provide a rationale for targeting acetylated STAT3 for chemoprevention and cancer therapy.
Assuntos
Metilação de DNA/genética , Genes Supressores de Tumor , Regiões Promotoras Genéticas/genética , Fator de Transcrição STAT3/metabolismo , Estilbenos/farmacologia , Acetilação , Análise de Variância , Animais , Western Blotting , Linhagem Celular Tumoral , Imunoprecipitação da Cromatina , Metilação de DNA/efeitos dos fármacos , Humanos , Imunoprecipitação , Camundongos , Microscopia Confocal , Microscopia de Fluorescência , Reação em Cadeia da Polimerase em Tempo Real , Resveratrol , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Fator de Transcrição STAT3/antagonistas & inibidores , Fator de Transcrição STAT3/genéticaRESUMO
BACKGROUND: Signaling pathways underlying BV8-mediated oncogenesis remain unknown. RESULTS: BV8-STAT3 forms a feed-forward loop in both normal and malignant myeloid cells and promotes tumor growth. CONCLUSION: JAK2/STAT3 signaling plays critical roles in BV8-mediated myeloid cell-dependent oncogenesis. SIGNIFICANCE: This study identifies a novel role of BV8-STAT3 signaling in mediating cross-talk between tumor microenvironment and tumor cells. An important role of BV8 in mobilization of myeloid cells and myeloid cell-dependent angiogenesis has been established. Recently, it has also been shown that granulocyte colony-stimulating factor (G-CSF)-induced BV8 expression is STAT3 dependent in CD11b(+)Gr1(+) myeloid cells. However, the BV8 downstream signaling pathway(s) intrinsic to myeloid cells crucial for angiogenesis, and potentially also for development of cancers of myeloid origin, remains largely unknown. Here we show that BV8 activates STAT3, which is critical for regulating genes important for both tumor cell proliferation/survival and tumor angiogenesis, in both normal and malignant myeloid cells. Further, BV8-induced STAT3 activation requires Janus-activated kinase 2 (JAK2) activity as shown by both genetic and pharmacologic inhibition. Knocking down BV8 in human myeloid leukemia cells inhibits STAT3 activity and expression of STAT3 downstream angiogenic and pro-proliferation/survival genes, leading to a decrease in tumor cell viability. BV8 shRNA expressing leukemia cells exhibit reduced STAT3 activity and tumor growth in vivo. Taken together, we have delineated a signaling pathway downstream of BV8 that plays critical roles in both the tumor microenvironment and malignant myeloid cells for angiogenesis and tumor cell proliferation/survival.
Assuntos
Hormônios Gastrointestinais/genética , Leucemia Mieloide Aguda/metabolismo , Células Mieloides/metabolismo , Neuropeptídeos/genética , Fator de Transcrição STAT3/metabolismo , Proteínas Angiogênicas/genética , Proteínas Angiogênicas/metabolismo , Animais , Linhagem Celular Tumoral , Proliferação de Células , Sobrevivência Celular , Retroalimentação Fisiológica , Hormônios Gastrointestinais/metabolismo , Hormônios Gastrointestinais/fisiologia , Regulação Neoplásica da Expressão Gênica , Técnicas de Silenciamento de Genes , Humanos , Janus Quinase 2/metabolismo , Leucemia Mieloide Aguda/patologia , Camundongos , Camundongos Endogâmicos BALB C , Camundongos Endogâmicos C57BL , Camundongos Knockout , Camundongos Nus , Transplante de Neoplasias , Neuropeptídeos/metabolismo , Neuropeptídeos/fisiologia , RNA Interferente Pequeno/genética , Receptores Acoplados a Proteínas G/metabolismo , Transdução de Sinais , Carga TumoralRESUMO
A common strategy for preparing tryptophan-derived epidithiodioxopiperazine (ETP) natural products containing a hydroxyl substituent adjacent to a quaternary carbon stereocenter is reported. This strategy is exemplified by enantioselective total syntheses of four heptacyclic ETP natural products--gliocladine C (6), leptosin D (7), T988C (8), and bionectin A (9)--starting with the di-(tert-butoxycarbonyl) derivative 17 of the trioxopiperazine natural product gliocladin C, which is readily available by enantioselective chemical synthesis. In addition, total syntheses of the enantiomer of gliocladine C (ent-6) and gliocladin A (11), the di(methylthio) congener of bionectin A, are reported. These syntheses illustrate a synthetic strategy wherein diversity in the dioxopiperazine unit of ETP natural products is introduced at a late stage in a synthetic sequence. In vitro cytotoxicity of compounds in this series against invasive human prostrate (DU145) and melanoma (A2058) cancer cell lines is described and compared to that of chaetocin A (4).
Assuntos
Alcaloides Indólicos/síntese química , Piperazinas/química , Pirrolidinonas/síntese química , Cristalografia por Raios X , Alcaloides Indólicos/química , Modelos Moleculares , Conformação Molecular , Piperazinas/síntese química , Pirrolidinonas/química , EstereoisomerismoRESUMO
The total syntheses of amphidinolide B1 and the proposed structure of amphidinolide B2 have been accomplished. Key aspects of this work include the development of a practical, non-transition-metal-mediated method for the construction of the C13-C15 diene, the identification of α-chelation and dipole minimization models for diastereoselective methyl ketone aldol reactions, the discovery of a spontaneous Horner-Wadsworth-Emmons macrocyclization strategy, and the development of a novel late stage method for construction of an allylic epoxide moiety. The originally proposed structure for amphidinolide B2 and diastereomers thereof display potent antitumor activities with IC50 values ranging from 3.3 to 94.5 nM against human solid and blood tumor cells. Of the different stereoisomers, the proposed structure of amphidinolide B2 is over 12-fold more potent than the C8,9-epimer and C18-epimer in human DU145 prostate cancer cells. These data suggest that the epoxide stereochemistry is a significant factor for anticancer activity.
Assuntos
Antineoplásicos/síntese química , Antineoplásicos/farmacologia , Compostos de Epóxi/química , Compostos de Epóxi/farmacologia , Macrolídeos/síntese química , Macrolídeos/farmacologia , Linhagem Celular Tumoral , Humanos , Concentração Inibidora 50 , Macrolídeos/química , Estrutura Molecular , EstereoisomerismoRESUMO
The immune system can act as an extrinsic suppressor of tumors. Therefore, tumor progression depends in part on mechanisms that downmodulate intrinsic immune surveillance. Identifying these inhibitory pathways may provide promising targets to enhance antitumor immunity. Here, we show that Stat3 is constitutively activated in diverse tumor-infiltrating immune cells, and ablating Stat3 in hematopoietic cells triggers an intrinsic immune-surveillance system that inhibits tumor growth and metastasis. We observed a markedly enhanced function of dendritic cells, T cells, natural killer (NK) cells and neutrophils in tumor-bearing mice with Stat3(-/-) hematopoietic cells, and showed that tumor regression requires immune cells. Targeting Stat3 with a small-molecule drug induces T cell- and NK cell-dependent growth inhibition of established tumors otherwise resistant to direct killing by the inhibitor. Our findings show that Stat3 signaling restrains natural tumor immune surveillance and that inhibiting hematopoietic Stat3 in tumor-bearing hosts elicits multicomponent therapeutic antitumor immunity.
Assuntos
Células da Medula Óssea/imunologia , Células Dendríticas/imunologia , Células Matadoras Naturais/imunologia , Neoplasias/imunologia , Fator de Transcrição STAT3/genética , Transdução de Sinais/imunologia , Subpopulações de Linfócitos T/imunologia , Linfócitos T/imunologia , Análise de Variância , Animais , Linhagem Celular Tumoral , Testes Imunológicos de Citotoxicidade , Citometria de Fluxo , Inativação Gênica , Imuno-Histoquímica , Camundongos , Camundongos Knockout , Fator de Transcrição STAT3/metabolismo , Transdução de Sinais/genéticaRESUMO
Three new acetophenone dimers or Acronychia-type acetophenones, acropyrone (1), acropyranol A (2), and acropyranol B (3), were isolated from the trunk bark of Acronychia pedunculata and structurally characterized, together with four known acetophenone dimers, acrovestone (4), acrovestenol (5), acrofolione A (6), and acrofolione B (7), the acetophenone monomer acronyline (8), and four furoquinoline alkaloids. The chemical structures of the new isolated compounds were elucidated unambiguously by spectroscopic data analysis. The cytotoxic activities of the isolated acetophenone dimers were evaluated against the DU145 prostate and A2058 melanoma human cancer cell lines as well as the NHDF normal cell line. Acrovestone (4) and acrovestenol (5) exhibited substantial cytotoxicity, with IC(50) values of 0.38 and 2.8 µM against A2058 melanoma cells as well as 0.93 and 2.7 µM against DU145 prostate cancer cells, respectively.
Assuntos
Acetofenonas/isolamento & purificação , Acetofenonas/farmacologia , Antineoplásicos Fitogênicos/isolamento & purificação , Antineoplásicos Fitogênicos/farmacologia , Rutaceae/química , Acetofenonas/química , Animais , Antineoplásicos Fitogênicos/química , Ensaios de Seleção de Medicamentos Antitumorais , Humanos , Masculino , Estrutura Molecular , Casca de Planta/químicaRESUMO
UNLABELLED: MicroRNAs (miRNAs) are small noncoding RNAs that regulate gene expression by interacting with the 3' untranslated region (3'-UTR) of multiple mRNAs. Recent studies have linked miRNAs to the development of cancer metastasis. In this study, we show that miR-194 is specifically expressed in the human gastrointestinal tract and kidney. Moreover, miR-194 is highly expressed in hepatic epithelial cells, but not in Kupffer cells or hepatic stellate cells, two types of mesenchymal cells in the liver. miR-194 expression was decreased in hepatocytes cultured in vitro, which had undergone a dedifferentiation process. Furthermore, expression of miR-194 was low in liver mesenchymal-like cancer cell lines. The overexpression of miR-194 in liver mesenchymal-like cancer cells reduced the expression of the mesenchymal cell marker N-cadherin and suppressed invasion and migration of the mesenchymal-like cancer cells both in vitro and in vivo. We further demonstrated that miR-194 targeted the 3'-UTRs of several genes that were involved in epithelial-mesenchymal transition and cancer metastasis. CONCLUSION: These results support a role of miR-194, which is specifically expressed in liver parenchymal cells, in preventing liver cancer cell metastasis.
Assuntos
Neoplasias Hepáticas/patologia , MicroRNAs/fisiologia , Metástase Neoplásica/prevenção & controle , Animais , Células Cultivadas , Células Epiteliais/metabolismo , Transição Epitelial-Mesenquimal/genética , Humanos , Fígado/metabolismo , Neoplasias Pulmonares/secundário , Camundongos , MicroRNAs/biossínteseRESUMO
Although tumor progression involves processes such as tissue invasion that can activate inflammatory responses, the immune system largely ignores or tolerates disseminated cancers. The mechanisms that block initiation of immune responses during cancer development are poorly understood. We report here that constitutive activation of Stat-3, a common oncogenic signaling pathway, suppresses tumor expression of proinflammatory mediators. Blocking Stat-3 in tumor cells increases expression of proinflammatory cytokines and chemokines that activate innate immunity and dendritic cells, leading to tumor-specific T-cell responses. In addition, constitutive Stat-3 activity induces production of pleiotropic factors that inhibit dendritic cell functional maturation. Tumor-derived factors inhibit dendritic cell maturation through Stat-3 activation in progenitor cells. Thus, inhibition of antitumor immunity involves a cascade of Stat-3 activation propagating from tumor to dendritic cells. We propose that tumor Stat-3 activity can mediate immune evasion by blocking both the production and sensing of inflammatory signals by multiple components of the immune system.
Assuntos
Proteínas de Ligação a DNA/fisiologia , Imunidade Inata/fisiologia , Melanoma Experimental/imunologia , Transdução de Sinais/fisiologia , Transativadores/fisiologia , Animais , Linhagem Celular Tumoral , Células Dendríticas/imunologia , Ensaio de Desvio de Mobilidade Eletroforética , Ensaio de Imunoadsorção Enzimática , Melanoma Experimental/metabolismo , Camundongos , Fator de Transcrição STAT3RESUMO
As a critical factor in the induction of angiogenesis, vascular endothelial growth factor (VEGF) has become an attractive target for anti-angiogenesis treatment. However, the side effects associated with most anti-VEGF agents limit their chronic use. Identification of naturally occurring VEGF inhibitors derived from diet is a potential alternative approach, with the advantage of known safety. To isolate natural inhibitors of VEGF, we established an in vitro tyrosine kinase assay to screen for diet-based agents that suppress VEGFR2 kinase activity. We found that a water-based extract from cinnamon (cinnamon extract, CE), one of the oldest and most popular spices, was a potent inhibitor of VEGFR2 kinase activity, directly inhibiting kinase activity of purified VEGFR2 as well as mitogen-activated protein kinase- and Stat3-mediated signaling pathway in endothelial cells. As a result, CE inhibited VEGF-induced endothelial cell proliferation, migration and tube formation in vitro, sprout formation from aortic ring ex vivo and tumor-induced blood vessel formation in vivo. Depletion of polyphenol from CE with polyvinylpyrrolidone abolished its anti-angiogenesis activity. While cinnamaldehyde, a component responsible for CE aroma, had little effect on VEGFR2 kinase activity, high-performance liquid chromatography-purified components of CE, procyanidin type A trimer (molecular weight, 864) and a tetramer (molecular weight, 1152) were found to inhibit kinase activity of purified VEGFR2 and VEGFR2 signaling, implicating procyanidin oligomers as active components in CE that inhibit angiogenesis. Our data revealed a novel activity in cinnamon and identified a natural VEGF inhibitor that could potentially be useful in cancer prevention and/or treatment.
Assuntos
Inibidores da Angiogênese/farmacologia , Cinnamomum zeylanicum/química , Células Endoteliais/efeitos dos fármacos , Extratos Vegetais/farmacologia , Receptor 2 de Fatores de Crescimento do Endotélio Vascular/antagonistas & inibidores , Inibidores da Angiogênese/isolamento & purificação , Animais , Aorta Torácica/efeitos dos fármacos , Biflavonoides/isolamento & purificação , Biflavonoides/farmacologia , Neoplasias da Mama/patologia , Catequina/isolamento & purificação , Catequina/farmacologia , Bovinos , Divisão Celular/efeitos dos fármacos , Linhagem Celular Tumoral/efeitos dos fármacos , Linhagem Celular Tumoral/enzimologia , Linhagem Celular Tumoral/transplante , Movimento Celular/efeitos dos fármacos , Células Cultivadas/citologia , Células Cultivadas/efeitos dos fármacos , Células Cultivadas/enzimologia , Embrião de Galinha , Colágeno , Combinação de Medicamentos , Células Endoteliais/citologia , Células Endoteliais/enzimologia , Feminino , Humanos , Laminina , Masculino , Camundongos , Camundongos SCID , Morfogênese/efeitos dos fármacos , Neovascularização Fisiológica/efeitos dos fármacos , Fosforilação/efeitos dos fármacos , Extratos Vegetais/isolamento & purificação , Proantocianidinas/isolamento & purificação , Proantocianidinas/farmacologia , Processamento de Proteína Pós-Traducional/efeitos dos fármacos , Proteoglicanas , Transdução de Sinais/efeitos dos fármacos , Ensaios Antitumorais Modelo de XenoenxertoRESUMO
We investigated the mechanism of action of LBH589, a novel broad-spectrum HDAC inhibitor belonging to the hydroxamate class, in Philadelphia chromosome-negative (Ph(-)) acute lymphoblastic leukemia (ALL). Two model human Ph(-) ALL cell lines (T-cell MOLT-4 and pre-B-cell Reh) were treated with LBH589 and evaluated for biologic and gene expression responses. Low nanomolar concentrations (IC(50): 5-20 nM) of LBH589 induced cell-cycle arrest, apoptosis, and histone (H3K9 and H4K8) hyperacetylation. LBH589 treatment increased mRNA levels of proapoptosis, growth arrest, and DNA damage repair genes including FANCG, FOXO3A, GADD45A, GADD45B, and GADD45G. The most dramatically expressed gene (up to 45-fold induction) observed after treatment with LBH589 is GADD45G. LBH589 treatment was associated with increased histone acetylation at the GADD45G promoter and phosphorylation of histone H2A.X. Furthermore, treatment with LBH589 was active against cultured primary Ph(-) ALL cells, including those from a relapsed patient, inducing loss of cell viability (up to 70%) and induction of GADD45G mRNA expression (up to 35-fold). Thus, LBH589 possesses potent growth inhibitory activity against including Ph(-) ALL cells associated with up-regulation of genes critical for DNA damage response and growth arrest. These findings provide a rationale for exploring the clinical activity of LBH589 in the treatment of patients with Ph(-) ALL.