RESUMO
Rocaglates are natural compounds that have been extensively studied for their ability to inhibit translation initiation. Rocaglates represent promising drug candidates for tumor treatment due to their growth-inhibitory effects on neoplastic cells. In contrast to natural rocaglates, synthetic analogues of rocaglates have been less comprehensively characterized, but were also shown to have similar effects on the process of protein translation. Here, we demonstrate an enhanced growth-inhibitory effect of synthetic rocaglates when combined with glucose anti-metabolite 2-deoxy-D-glucose (2DG) in different cancer cell lines. Moreover, we unravel a new aspect in the mechanism of action of synthetic rocaglates involving reduction of glucose uptake mediated by downregulation or abrogation of glucose transporter GLUT-1 expression. Importantly, cells with genetically induced resistance to synthetic rocaglates showed substantially less pronounced treatment effect on glucose metabolism and did not demonstrate GLUT-1 downregulation, pointing at the crucial role of this mechanism for the anti-tumor activity of the synthetic rocaglates. Transcriptome profiling revealed glycolysis as one of the major pathways differentially regulated in sensitive and resistant cells. Analysis of synthetic rocaglate efficacy in a 3D tissue context with a co-culture of tumor and normal cells demonstrated a selective effect on tumor cells and substantiated the mechanistic observations obtained in cancer cell lines. Increased glucose uptake and metabolism is a universal feature across different tumor types. Therefore, targeting this feature by synthetic rocaglates could represent a promising direction for exploitation of rocaglates in novel anti-tumor therapies.
Assuntos
Benzofuranos/uso terapêutico , Transportador de Glucose Tipo 1/metabolismo , Glucose/metabolismo , Neoplasias/tratamento farmacológico , Benzofuranos/farmacologia , Proliferação de Células , HumanosRESUMO
Chronic lymphocytic leukemia is a malignancy of mature B cells that strongly depend on microenvironmental factors, and their deprivation has been identified as a promising treatment approach for this incurable disease. Cytokine array screening of 247 chronic lymphocytic leukemia serum samples revealed elevated levels of tumor necrosis factor (TNF) receptor-1 which were associated with poor clinical outcome. We detected a microenvironment-induced expression of TNF receptor-1 in chronic lymphocytic leukemia cells in vitro, and an aberrantly high expression of this receptor in the proliferation centers of patients' lymph nodes. Stimulation of TNF receptor-1 with TNF-α enhanced nuclear factor κ-light-chain-enhancer of activated B cells (NFκB) activity and viability of chronic lymphocytic leukemia cells, which was inhibited by wogonin. The therapeutic effects of wogonin were analyzed in mice after adoptive transfer of Eµ-T-cell leukemia 1 (TCL1) leukemic cells. Wogonin treatment prevented leukemia development when given early after transplantation. The treatment of full-blown leukemia resulted in the loss of the TNF receptor-1 on chronic lymphocytic leukemia cells and their mobilization to blood. Targeting TNF receptor-1 signaling is therefore proposed for the treatment of chronic lymphocytic leukemia.
Assuntos
Flavanonas/uso terapêutico , Leucemia Linfocítica Crônica de Células B/tratamento farmacológico , Receptores do Fator de Necrose Tumoral/metabolismo , Transdução de Sinais , Transferência Adotiva , Animais , Técnicas de Cocultura , Humanos , Leucemia/patologia , Leucemia/prevenção & controle , Leucemia Linfocítica Crônica de Células B/metabolismo , Linfonodos/metabolismo , Camundongos , Receptores Tipo I de Fatores de Necrose Tumoral/metabolismo , Células Tumorais Cultivadas , Microambiente Tumoral/efeitos dos fármacosRESUMO
Multiple myeloma (MM) is an incurable malignancy by the presently known therapies. TRAIL is a promising anticancer agent that virtually not shows any toxicity to normal cells. We have recently carried out clinical trials with a human circularly permuted TRAIL, CPT, against MM saw a partial response in approximate 20-30% of patients. In the current study, we investigated the cause of CPT resistance and revealed that the majority of the MM patients express elevated levels of c-FLIP. Knockdown of c-FLIP expression by siRNA alone was sufficient to increase CPT-mediated apoptosis in a CPT-resistant human MM cell line U266. To overcome CPT resistance, we investigated the combination of CPT with Rocaglamides(s) in MM which has been shown to inhibit c-FLIP expression in vitro. We show that Rocaglamide(s) overcomes CPT resistance in U266 in vitro and significant increases in anti-tumor efficacies of CPT in mice xenografted with U266. Similar results were also obtained in mice xenografted with the CPT-resistant human acute T-cell leukemia cell line Molt-4. Our study suggests that the combination of Rocaglamide(s) with CPT may provide a more efficient treatment against myeloma and leukemia.
Assuntos
Benzofuranos/uso terapêutico , Leucemia-Linfoma de Células T do Adulto/tratamento farmacológico , Mieloma Múltiplo/tratamento farmacológico , Ligante Indutor de Apoptose Relacionado a TNF/uso terapêutico , Animais , Proteína Reguladora de Apoptosis Semelhante a CASP8 e FADD/análise , Proteína Reguladora de Apoptosis Semelhante a CASP8 e FADD/fisiologia , Linhagem Celular Tumoral , Resistencia a Medicamentos Antineoplásicos , Humanos , Camundongos , Proteínas Recombinantes/uso terapêutico , Ensaios Antitumorais Modelo de XenoenxertoRESUMO
Chemotherapy is one of the pillars of anti-cancer therapy. Although chemotherapeutics cause regression of the primary tumor, many chemotherapeutics are often shown to induce or accelerate metastasis formation. Moreover, metastatic tumors are largely resistant against chemotherapy. As more than 90% of cancer patients die due to metastases and not due to primary tumor formation, novel drugs are needed to overcome these shortcomings. In this study, we identified the anticancer phytochemical Rocaglamide (Roc-A) to be an inhibitor of cancer cell migration, a crucial event in metastasis formation. We show that Roc-A inhibits cellular migration and invasion independently of its anti-proliferative and cytotoxic effects in different types of human cancer cells. Mechanistically, Roc-A treatment induces F-actin-based morphological changes in membrane protrusions. Further investigation of the molecular mechanisms revealed that Roc-A inhibits the activities of the small GTPases RhoA, Rac1 and Cdc42, the master regulators of cellular migration. Taken together, our results provide evidence that Roc-A may be a lead candidate for a new class of anticancer drugs that inhibit metastasis formation.
Assuntos
Antineoplásicos/farmacologia , Benzofuranos/farmacologia , Movimento Celular/efeitos dos fármacos , Proteínas rho de Ligação ao GTP/metabolismo , Linhagem Celular Tumoral , Inibidores Enzimáticos/farmacologia , Humanos , Proteínas rho de Ligação ao GTP/efeitos dos fármacosRESUMO
Over-expression of Bcl-2, Bcl-xL and Bcl-w is frequently associated with cancer resistance to chemotherapy. Navitoclax (ABT-263), an orally bio-available small-molecule mimetic of the Bcl-2 homology domain 3, specifically inhibits Bcl-2, Bcl-xL and Bcl-w. Despite promising results obtained from the clinical trials, the use of Navitoclax in patients is dose-limited due to induction of death of platelets via inhibition of Bcl-xL and subsequent thrombocytopenia. This side effect limits the use of Navitoclax in low doses and to very sensitive tumors. In this study, we show that HTLV-1-associated adult T-cell leukemia/lymphoma (ATL) cells, which over-express Bcl-2, Bcl-xL and Bcl-w, show a 10- to 20-fold higher sensitivity (EC50 = â¼ 25-50 nM) to Navitoclax compared to non-HTLV-1-associated leukemic cells (EC50 = â¼ 1 µM). Investigation of the molecular mechanisms revealed that the HTLV-1 oncogenic protein Tax up-regulates expression of the pro-apoptotic protein Bax which enhances the therapeutic efficacy of Navitoclax. In addition, we show that agents that inhibit the transcription elongation or translation initiation such as Wogonin and Roc-A can further decrease the effective dose of Navitoclax. Our study suggests that HTLV-1 ATL may be a good candidate disease for low dose Navitoclax therapy and probably with less risk of thrombocytopenia.
Assuntos
Compostos de Anilina/farmacologia , Antineoplásicos/farmacologia , Infecções por HTLV-I/patologia , Leucemia-Linfoma de Células T do Adulto/patologia , Sulfonamidas/farmacologia , Proteína X Associada a bcl-2/biossíntese , Adulto , Western Blotting , Linhagem Celular Tumoral , Infecções por HTLV-I/metabolismo , Vírus Linfotrópico T Tipo 1 Humano , Humanos , Leucemia-Linfoma de Células T do Adulto/metabolismo , Leucemia-Linfoma de Células T do Adulto/virologia , TransfecçãoRESUMO
Natural compounds are an important source for drug development. With an increasing cancer rate worldwide there is an urgent quest for new anti-cancer drugs. In this study, we show that a group of dolabrane-type of diterpenes, collectively named tagalsins, isolated from the Chinese mangrove genus Ceriops has potent cytotoxicity on a panel of hematologic cancer cells. Investigation of the molecular mechanisms by which tagalsins kill malignant cells revealed that it induces a ROS-mediated damage of DNA. This event leads to apoptosis induction and blockage of cell cycle progression at S-G2 phase via activation of the ATM/ATR-Chk1/Chk2 check point pathway. We further show that tagalsins suppress growth of human T-cell leukemia xenografts in vivo. Tagalsins show only minor toxicity on healthy cells and are well tolerated by mice. Our study shows a therapeutic potential of tagalsins for the treatment of hematologic malignancies and a new source of anticancer drugs.
Assuntos
Apoptose/efeitos dos fármacos , Proteínas Mutadas de Ataxia Telangiectasia/metabolismo , Pontos de Checagem do Ciclo Celular/efeitos dos fármacos , Quinase do Ponto de Checagem 2/metabolismo , Diterpenos/farmacologia , Proteínas Quinases/metabolismo , Animais , Antineoplásicos/farmacologia , Linhagem Celular Tumoral , Quinase 1 do Ponto de Checagem , Dano ao DNA/efeitos dos fármacos , Fase G2/efeitos dos fármacos , Humanos , Células Jurkat , Leucemia de Células T/tratamento farmacológico , Leucemia de Células T/metabolismo , Camundongos , Espécies Reativas de Oxigênio/metabolismo , Rhizophoraceae/química , Fase S/efeitos dos fármacos , Proteínas Supressoras de Tumor/metabolismoRESUMO
Chemical examination of the barks of mangrove plant Ceriops tagal resulted in the isolation of six new dolabrane-type diterpenes with the trivial names of tagalenes A-F (1-6), together with 10 known analogues. The structures of new compounds were elucidated by extensive spectroscopic data analyses. Tagalenes A-C (1-3) are characterized by 18-nordolabrane scaffold, while tagalene F (6) featured by a 2,3-seco dolabrane derivative. Antitumor assay revealed that seven compounds exhibited potent inhibitory effects against a panel of tumor cell lines with IC50<10 µM, while tagalsin C (8) exerted the most potent activities in comparison with the IC50 values of the rest compounds. The primary structure-activity relationship is discussed. Tagalsin C also exerted the potent effects against a panel of drug-resistant human tumor cell lines, indicating it to be a promising molecule for further evaluation as an antitumor lead compound.
Assuntos
Antineoplásicos Fitogênicos/farmacologia , Diterpenos/farmacologia , Rhizophoraceae/química , Antineoplásicos Fitogênicos/isolamento & purificação , Linhagem Celular Tumoral , Diterpenos/isolamento & purificação , Humanos , Estrutura Molecular , Casca de Planta/química , Relação Estrutura-AtividadeRESUMO
Tumor initiation, progression and resistance to therapies are tightly associated with over-expression of anti-apoptotic proteins Bcl-2, Bcl-x(L), Bcl-w and Mcl-1. ABT-263 (Navitoclax), an orally bio-available small-molecule mimetic of the Bcl-2 homology domain 3, inhibits Bcl-2, Bcl-x(L), and Bcl-w and has shown anti-cancer effects mainly on lymphomas and lymphocytic leukemia. Despite promising results obtained from the clinical trials, the use of ABT-263 in patients is dose-limited due to causing thrombocytopenia via inhibition of Bcl-x(L) in platelets. ABT-199 specifically inhibits Bcl-2; however, its use is limited to tumors over-expressing only Bcl-2. Besides, many tumors resist treatment due to high levels of Mcl-1 expression or develop resistance via up-regulation of Mcl-1 during long-term exposure. These obstacles highlight the demand to improve the ABT-263-based therapy. In this study, we show that anti-cancer flavones, e.g., wogonin, baicalein, apigenin, chrysin and luteolin enhance ABT-263-induced apoptosis in different cancer cell lines and in primary AML and ALL cells by down-regulation of Mcl-1 expression. Importantly, wogonin does not enhance the toxicity of ABT-263 to proliferating normal T cells and thrombocytes. Wogonin also potentiates the lethality of ABT-263 in cancer cells which have acquired resistance to ABT-263. Furthermore, we show that combination of wogonin with ABT-263 promotes in vivo tumor regression in a human T-cell leukemia xenograft mouse model. Our study demonstrates that wogonin (and related flavones) reduce the effective dose of ABT-263 thereby possibly decreasing the risk of adverse side effects.
Assuntos
Compostos de Anilina/farmacologia , Antineoplásicos/farmacologia , Quinase 9 Dependente de Ciclina/antagonistas & inibidores , Flavanonas/farmacologia , Flavonas/farmacologia , Sulfonamidas/farmacologia , Animais , Apoptose/efeitos dos fármacos , Linhagem Celular Tumoral , Resistencia a Medicamentos Antineoplásicos , Sinergismo Farmacológico , Humanos , Camundongos , Ensaios Antitumorais Modelo de XenoenxertoRESUMO
Rocaglamides (= flavaglines) are potent natural anti-cancer phytochemicals that inhibit cancer growth at nanomolar concentrations by the following mechanisms: (1) inhibition of translation initiation via inhibition of phosphorylation of the mRNA cap-binding eukaryotic translation initiation factor eIF4E and stabilization of RNA-binding of the translation initiation factor eIF4A in the eIF4F complex; (2) blocking cell cycle progression by activation of the ATM/ATR-Chk1/Chk2 checkpoint pathway; (3) inactivation of the heat shock factor 1 (HSF1) leading to up-regulation of thioredoxin-interacting protein (TXNIP) and consequent reduction of glucose uptake and (4) induction of apoptosis through activation of the MAPK p38 and JNK and inhibition of the Ras-CRaf-MEK-ERK signaling pathway. Besides the anti-cancer activities, rocaglamides are also shown to protect primary cells from chemotherapy-induced cell death and alleviate inflammation- and drug-induced injury in neuronal tissues. This review will focus on the recently discovered molecular mechanisms of the actions of rocaglamides and highlights the benefits of using rocaglamides in cancer treatment.
Assuntos
Antineoplásicos Fitogênicos/farmacologia , Benzofuranos/farmacologia , Sistema de Sinalização das MAP Quinases/efeitos dos fármacos , Neoplasias/tratamento farmacológico , Animais , Antineoplásicos Fitogênicos/uso terapêutico , Benzofuranos/uso terapêutico , Pontos de Checagem do Ciclo Celular/efeitos dos fármacos , Proliferação de Células/efeitos dos fármacos , Regulação Neoplásica da Expressão Gênica/efeitos dos fármacos , Humanos , Neoplasias/metabolismo , Ensaios Antitumorais Modelo de XenoenxertoRESUMO
The role of Wilms' tumor suppressor 1 (WT1) in leukemogenesis has been investigated mostly in acute (AML) and chronic (CML) myeloid leukemias. So far, its oncogenic role has been controversially discussed because both overexpression and inactivating mutations are found. A recent study on primary samples from patients with acute T-cell leukemia (T-ALL) revealed that most of them do not express WT1 proteins although they express WT1 mRNA. In our study, we investigated WT-1 expression in ten T-ALL cell lines established from leukemia/lymphoma patients. We show that consistent with the finding in primary T-ALL cells, most of the leukemic T-cell lines tested do not overexpress WT1 proteins. We found that leukemic T-cells overexpressing WT1 protein produce higher levels of CD95L and show elevated CD95L-mediated activation-induced cell death (AICD) compared to cells lacking or expressing low levels of WT1. Ectopic expression of WT1 in the WT1-nonexpressing leukemic T-cell line increases CD95L expression and elevates activation-induced apoptosis, whereas silencing WT1 expression in the WT1-overexpressing leukemic T-cell line by siRNA confers reduced CD95L expression and reduction in AICD. Chromatin immunoprecipitation and luciferase-promoter reporter analysis demonstrate that WT1 binds to and enhances CD95L promoter activity through the Egr-binding sites. Our study provides a new role of WT1 in regulation of CD95L-mediated cell death.
Assuntos
Apoptose/efeitos dos fármacos , Proteína Ligante Fas/metabolismo , Leucemia de Células T/patologia , Fatores de Transcrição/metabolismo , Proteínas WT1/metabolismo , Western Blotting , Proliferação de Células/efeitos dos fármacos , Imunoprecipitação da Cromatina , Ensaio de Desvio de Mobilidade Eletroforética , Proteína Ligante Fas/genética , Humanos , Leucemia de Células T/genética , Leucemia de Células T/metabolismo , Ativação Linfocitária , Regiões Promotoras Genéticas/genética , RNA Mensageiro/genética , RNA Interferente Pequeno/genética , Reação em Cadeia da Polimerase em Tempo Real , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Células Tumorais Cultivadas , Proteínas WT1/antagonistas & inibidores , Proteínas WT1/genéticaRESUMO
Targeting the cancer cell cycle machinery is an important strategy for cancer treatment. Cdc25A is an essential regulator of cycle progression and checkpoint response. Over-expression of Cdc25A occurs often in human cancers. In this study, we show that Rocaglamide-A (Roc-A), a natural anticancer compound isolated from the medicinal plant Aglaia, induces a rapid phosphorylation of Cdc25A and its subsequent degradation and, thereby, blocks cell cycle progression of tumor cells at the G1-S phase. Roc-A has previously been shown to inhibit tumor proliferation by blocking protein synthesis. In this study, we demonstrate that besides the translation inhibition Roc-A can induce a rapid degradation of Cdc25A by activation of the ATM/ATR-Chk1/Chk2 checkpoint pathway. However, Roc-A has no influence on cell cycle progression in proliferating normal T lymphocytes. Investigation of the molecular basis of tumor selectivity of Roc-A by a time-resolved microarray analysis of leukemic vs. proliferating normal T lymphocytes revealed that Roc-A activates different sets of genes in tumor cells compared with normal cells. In particular, Roc-A selectively stimulates a set of genes responsive to DNA replication stress in leukemic but not in normal T lymphocytes. These findings further support the development of Rocaglamide for antitumor therapy.
Assuntos
Antineoplásicos/farmacologia , Proteínas Mutadas de Ataxia Telangiectasia/metabolismo , Benzofuranos/farmacologia , Quinase do Ponto de Checagem 2/metabolismo , Proteínas Quinases/metabolismo , Proteínas Mutadas de Ataxia Telangiectasia/efeitos dos fármacos , Linhagem Celular Tumoral , Proliferação de Células/efeitos dos fármacos , Quinase 1 do Ponto de Checagem , Quinase do Ponto de Checagem 2/genética , Dano ao DNA/efeitos dos fármacos , Células HCT116 , Células HT29 , Células Hep G2 , Humanos , Células Jurkat , Leucemia/tratamento farmacológico , Células MCF-7 , Fosforilação/efeitos dos fármacos , Extratos Vegetais/farmacologia , Biossíntese de Proteínas/efeitos dos fármacos , Proteínas Quinases/genética , Interferência de RNA , RNA Interferente Pequeno , Pontos de Checagem da Fase S do Ciclo Celular/efeitos dos fármacos , Linfócitos T/efeitos dos fármacos , Fosfatases cdc25/biossíntese , Fosfatases cdc25/genética , Fosfatases cdc25/metabolismoRESUMO
Hodgkin/Reed-Sternberg lymphoma (HL) is a clonal B-cell-related malignancy. Although many patients with HL can be cured by the current regimen of high-dose multi-agent chemotherapy, the treatment causes high risks of later pathologies including secondary malignancies. This fact highlights the demand to develop rational treatment for HL. Survival and growth of HL cells are largely dependent on their microenvironment. In this study, using the HL cell lines L1236 and KM-H2 as model systems, we investigated the role of IL-4/IL-13 signaling in regulation of drug sensitivity and resistance in HL. We show that specific blocking of IL-4 and IL-13-mediated STAT6 activation by either an IL-4-binding fusion protein APG598 or an IL-4R antagonist APG201 (R121D/Y124D) renders HL cells more prone to apoptotic killing by chemotherapeutic drugs such as Mitomycin C, 5-Fluorouracil, Etopside, Doxorubicin and Paclitaxel. This effect is due to inhibition of STAT6-mediated elevation of expression of the anti-apoptotic Bcl-2 family protein Bcl-xL. Employing ChIP analysis in combination with APG201 or STAT6-specific siRNA we identified a defined STAT6-binding site in the Bcl-xL promoter region from -1967 to -1957 of the transcription start site. Our data demonstrate that the IL-4/IL-13-STAT6-Bcl-xL axis may be an important target for HL treatment. This study also suggests that combination of classical chemotherapeutic drugs with the IL-4/IL-13 antagonists may enhance efficacy and reduce risks of toxicity from high dose of drugs in HL treatment.
Assuntos
Doença de Hodgkin/tratamento farmacológico , Interleucina-13/antagonistas & inibidores , Interleucina-4/antagonistas & inibidores , Fator de Transcrição STAT6/genética , Proteína bcl-X/genética , Antibióticos Antineoplásicos/farmacologia , Antineoplásicos Fitogênicos/farmacologia , Apoptose/efeitos dos fármacos , Linhagem Celular Tumoral , Doxorrubicina/farmacologia , Ativação Enzimática/efeitos dos fármacos , Etoposídeo/farmacologia , Fluoruracila/farmacologia , Doença de Hodgkin/genética , Doença de Hodgkin/metabolismo , Humanos , Interleucina-13/metabolismo , Interleucina-4/metabolismo , Mitomicina/farmacologia , Paclitaxel/farmacologia , Regiões Promotoras Genéticas , Interferência de RNA , RNA Interferente Pequeno , Células de Reed-Sternberg/efeitos dos fármacos , Células de Reed-Sternberg/metabolismo , Fator de Transcrição STAT6/metabolismo , Transdução de Sinais/efeitos dos fármacos , Proteína bcl-X/biossínteseRESUMO
The traditional Chinese medicine (TCM) uses a combination of different natural products based on practical experiences. To better understand the therapeutic functions of TCM, large efforts have been made to identify the principle constituents of TCM and to unravel the molecular mechanisms behind the efficacy observed. This review aims to summarize research results obtained from the most intensively studied TCM phytochemical compounds namely the alkaloids Berberine, Evodiamine; anthraquinones Emodin, Aloe-emodin, Rhein; the terpenoids Artemisinin, Celastrol, Triptolide; the flavones Apigenin, Chrysin, Wogonin, Baicalein; and the cyclopenta[b]benzofuran derivatives Rocaglamide. Most of them have been originally identified as anti-inflammatory and anti-viral reagents and are now known to also possess anti-tumor activities by targeting the apoptosis pathways in cancer. This review also intends to give an overview of the mechanisms of action identified so far. These breakthrough findings may have important implications for targeted-cancer therapy and for modernization of TCM.
Assuntos
Apoptose , Medicina Tradicional Chinesa/métodos , Neoplasias/tratamento farmacológico , Animais , Dano ao DNA , Desenho de Fármacos , Humanos , Sistema de Sinalização das MAP Quinases , NF-kappa B/antagonistas & inibidores , NF-kappa B/metabolismo , Espécies Reativas de OxigênioRESUMO
Rocaglamides are potent natural anticancer products that inhibit proliferation of various cancer cells at nanomolar concentrations. We have recently shown that these compounds prevent tumor growth and sensitize resistant cancer cells to apoptosis by blocking the MEK-ERK-eIF4 pathway. However, their direct molecular target(s) remain(s) unknown. In this study, using an affinity chromatography approach we discovered that prohibitin (PHB) 1 and 2 are the direct targets of rocaglamides. Binding of rocaglamides to PHB prevents interaction between PHB and CRaf and, thereby, inhibits CRaf activation and subsequently CRaf-MEK-ERK signaling. Moreover, knockdown of PHB mimicked the effects of rocaglamides on the CRaf-MEK-ERK pathway and cell cycle progression. Thus, our finding suggests that rocaglamides are a new type of anticancer agent and that they may serve as a small-molecular tool for studying PHB-mediated cellular processes.
Assuntos
Antineoplásicos Fitogênicos/farmacologia , Benzofuranos/farmacologia , MAP Quinases Reguladas por Sinal Extracelular/antagonistas & inibidores , MAP Quinase Quinase Quinases/antagonistas & inibidores , Sistema de Sinalização das MAP Quinases/efeitos dos fármacos , Proteínas Proto-Oncogênicas c-raf/antagonistas & inibidores , Proteínas Repressoras/antagonistas & inibidores , Aglaia/química , Antineoplásicos Fitogênicos/química , Antineoplásicos Fitogênicos/isolamento & purificação , Benzofuranos/química , Benzofuranos/isolamento & purificação , Ciclo Celular/efeitos dos fármacos , Proliferação de Células/efeitos dos fármacos , Células Cultivadas , Ensaios de Seleção de Medicamentos Antitumorais , MAP Quinases Reguladas por Sinal Extracelular/metabolismo , Células HEK293 , Células HeLa , Humanos , Células Jurkat , MAP Quinase Quinase Quinases/metabolismo , Proibitinas , Proteínas Proto-Oncogênicas c-raf/metabolismo , Proteínas Repressoras/metabolismo , Relação Estrutura-AtividadeRESUMO
Curcumin is the active ingredient of the spice turmeric and has been shown to have a number of pharmacologic and therapeutic activities including antioxidant, anti-microbial, anti-inflammatory, and anti-carcinogenic properties. The anti-inflammatory effects of curcumin have primarily been attributed to its inhibitory effect on NF-κB activity due to redox regulation. In this study, we show that curcumin is an immunosuppressive phytochemical that blocks T cell-activation-induced Ca(2+) mobilization with IC(50) = â¼12.5 µM and thereby prevents NFAT activation and NFAT-regulated cytokine expression. This finding provides a new mechanism for curcumin-mediated anti-inflammatory and immunosuppressive function. We also show that curcumin can synergize with CsA to enhance immunosuppressive activity because of different inhibitory mechanisms. Furthermore, because Ca(2+) is also the secondary messenger crucial for the TCR-induced NF-κB signaling pathway, our finding also provides another mechanism by which curcumin suppresses NF-κB activation.
Assuntos
Anti-Inflamatórios não Esteroides/farmacologia , Sinalização do Cálcio/efeitos dos fármacos , Cálcio/metabolismo , Curcumina/farmacologia , Ativação Linfocitária/efeitos dos fármacos , NF-kappa B/metabolismo , Fatores de Transcrição NFATC/metabolismo , Linfócitos T/metabolismo , Sinalização do Cálcio/fisiologia , Ciclosporina/farmacologia , Citocinas/biossíntese , Citocinas/genética , Regulação da Expressão Gênica/efeitos dos fármacos , Regulação da Expressão Gênica/fisiologia , Humanos , Imunossupressores/farmacologia , Células Jurkat , Ativação Linfocitária/fisiologia , NF-kappa B/genética , Fatores de Transcrição NFATC/genética , Oxirredução/efeitos dos fármacos , Receptores de Antígenos de Linfócitos T/genética , Receptores de Antígenos de Linfócitos T/metabolismo , Linfócitos T/citologiaRESUMO
Although most of the patients with Hodgkin's lymphoma (HL) can be cured by the current regimen of high-dose multiagent chemotherapy, the treatment causes high risks of later toxicities including secondary malignancies. Therefore, new rational strategies are needed for HL treatment. Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) is a promising anticancer agent due to its tumor selectivity and its lack of toxicity for normal cells. Unfortunately, many cancers remain resistant to TRAIL including HL. HL is characterized by enhanced expression of cellular caspase-8 (FLICE)-inhibitory protein (c-FLIP) and X-linked inhibitor of apoptosis (XIAP), which block receptor-mediated apoptosis by inhibiting caspase-8 and caspase-3, respectively. We have recently discovered the herbal compound Rocaglamide, which breaks TRAIL-resistance in acute T cell leukemia through inhibition of c-FLIP expression. We have also shown that small molecule XIAP inhibitors can sensitize TRAIL-mediated apoptosis in several resistant tumors. However, whether targeting XIAP or c-FLIP is also a suitable strategy to prime HL cells for TRAIL-induced apoptosis has not yet been investigated. In our study, we show that Rocaglamide suppresses c-FLIP expression in HL cells in a dose- and time-dependent manner. However, downregulation of c-FLIP alone was not sufficient to sensitize TRAIL-induced apoptosis in HL cells. Similarly, treatment of HL cells with a small molecule XIAP inhibitor resulted in a moderate induction of apoptosis. However, inhibition of XIAP alone was also not sufficient to enhance TRAIL-induced cell death. Synergistic increase in TRAIL-mediated killing of HL cells was only obtained by combination of Rocaglamide and XIAP inhibitors. Our study demonstrates that targeting both c-FLIP and XIAP are necessary for an efficient treatment of HL.
Assuntos
Apoptose/fisiologia , Benzofuranos/farmacologia , Doença de Hodgkin/patologia , Ligante Indutor de Apoptose Relacionado a TNF/fisiologia , Proteínas Inibidoras de Apoptose Ligadas ao Cromossomo X/antagonistas & inibidores , Proteína Reguladora de Apoptosis Semelhante a CASP8 e FADD/fisiologia , Linhagem Celular Tumoral , HumanosRESUMO
Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) is a promising anticancer agent that kills various tumor cells without damaging normal tissues. However, many cancers remain resistant to TRAIL. To overcome TRAIL resistance, combination therapies using sensitizers of the TRAIL pathway would be an efficacious approach. To investigate potential sensitizers of TRAIL-induced apoptosis, we used TRAIL-resistant human T cell leukemia virus type 1 (HTLV-1)-associated adult T cell leukemia/lymphoma (ATL) cells as a model system. So far, HTLV-1-associated ATL is incurable by presently known therapies. Here, we show that wogonin and the structurally related natural flavones apigenin and chrysin break TRAIL resistance in HTLV-1-associated ATL by transcriptional down-regulation of c-FLIP, a key inhibitor of death receptor signaling, and by up-regulation of TRAIL receptor 2 (TRAIL-R2). This effect is mediated through transcriptional inhibition of the p53 antagonist murine double minute 2 (Mdm2), leading to an increase in p53 levels and, consequently, to up-regulation of the p53 target gene TRAIL-R2. We also show that these flavones can sensitize to TNFα- and CD95-mediated cell death. Furthermore, we show that wogonin, apigenin, and chrysin also enhance TRAIL-mediated apoptosis in other human cancer cell lines including breast cancer cell line MDA-MB-231, colon cancer cell line HT-29, hepatocellular carcinoma cell line HepG2, melanoma cell line SK-MEL-37, and pancreatic carcinoma cell line Capan-1 by the same mechanism. Thus, our study suggests the potential use of these flavones as an adjuvant for TRAIL-mediated anticancer therapy.
Assuntos
Proteína Reguladora de Apoptosis Semelhante a CASP8 e FADD/metabolismo , Regulação para Baixo/efeitos dos fármacos , Resistencia a Medicamentos Antineoplásicos/efeitos dos fármacos , Flavonas/farmacologia , Receptores do Ligante Indutor de Apoptose Relacionado a TNF/metabolismo , Ligante Indutor de Apoptose Relacionado a TNF/farmacologia , Regulação para Cima/efeitos dos fármacos , Anticorpos/imunologia , Antineoplásicos/farmacologia , Apigenina/farmacologia , Apoptose/efeitos dos fármacos , Produtos Biológicos/farmacologia , Proteína Reguladora de Apoptosis Semelhante a CASP8 e FADD/genética , Linhagem Celular Tumoral , Flavanonas/farmacologia , Flavonoides/farmacologia , Humanos , Leucemia de Células T/patologia , Linfoma de Células T/patologia , Proteínas Proto-Oncogênicas c-mdm2/genética , Receptores do Ligante Indutor de Apoptose Relacionado a TNF/genética , Transcrição Gênica/efeitos dos fármacos , Fator de Necrose Tumoral alfa/farmacologia , Proteína Supressora de Tumor p53/genética , Proteína Supressora de Tumor p53/metabolismo , Receptor fas/imunologiaRESUMO
The early growth response gene product Egr-1 has been shown to have great impact on growth, proliferation, and differentiation in a wide variety of cells, including T cells. In this study, we show that Egr-1 is rapidly induced upon T cell stimulation and is expressed predominantly in T helper type 2 (Th2) compared with type 1 (Th1) cells. We further investigate the role of Egr-1 in regulation of the Th2 cytokine interleukin-4 (IL-4) expression. IL-4 is a key Th2 cytokine that regulates humoral immunity and also causes allergic inflammation. Regulation of IL-4 gene transcription in Th2 cells has been shown to be controlled by multiple T cell receptor (TCR)-induced transcription factors. However, only a few transcription factors were shown to be selectively induced in differentiated Th2 cells in response to TCR stimulation. Chromatin immunoprecipitation analysis demonstrates that Egr-1 binds to the IL-4 promoter in vivo upon T cell stimulation. Ectopic expression of Egr-1 enhances endogenous IL-4 mRNA expression and elevates IL-4 promoter activity. We also show that Egr-1, nuclear factor of activated T cell, and NF-kappaB cooperatively bind to an NFAT/NF-kappaB-overlapping IL-4 enhancer element and activate the IL-4 promoter synergistically. Furthermore, we show that antisense oligonucleotides that knock down Egr-1 expression attenuate IL-4 transcription. Our study provides the first evidence that Egr-1 protein is differentially expressed in Th1 and Th2 cells and is involved in the acute phase of the IL-4 transcription in response to TCR stimulation.
Assuntos
Proteína 1 de Resposta de Crescimento Precoce/metabolismo , Regulação da Expressão Gênica , Interleucina-4/genética , Células Th1/metabolismo , Células Th2/metabolismo , Transcrição Gênica , Animais , Sítios de Ligação , Diferenciação Celular , Linhagem Celular , Regulação para Baixo , Proteína 1 de Resposta de Crescimento Precoce/genética , Elementos Facilitadores Genéticos/genética , Humanos , Camundongos , NF-kappa B/metabolismo , Fatores de Transcrição NFATC/metabolismo , Oligonucleotídeos Antissenso/genética , Oligonucleotídeos Antissenso/metabolismo , Regiões Promotoras Genéticas/genética , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Receptores de Antígenos de Linfócitos T/metabolismo , Células Th1/citologia , Células Th2/citologia , Fatores de TempoRESUMO
Traditional Chinese medicines have been recently recognized as a new source of anticancer drugs and new chemotherapy adjuvant to enhance the efficacy of chemotherapy and to ameliorate the side effects of cancer chemotherapies however their healing mechanisms are still largely unknown. Scutellaria baicalensis is one of the most popular and multi-purpose herb used in China traditionally for treatment of inflammation, hypertension, cardiovascular diseases, and bacterial and viral infections. Accumulating evidence demonstrate that Scutellaria also possesses potent anticancer activities. The bioactive components of Scutellaria have been confirmed to be flavones. The major constituents of Scutellaria baicalensis are Wogonin, Baicalein and Baicalin. These phytochemicals are not only cytostatic but also cytotoxic to various human tumor cell lines in vitro and inhibit tumor growth in vivo. Most importantly, they show almost no or minor toxicity to normal epithelial and normal peripheral blood and myeloid cells. The antitumor functions of these flavones are largely due to their abilities to scavenge oxidative radicals, to attenuate NF-kappaB activity, to inhibit several genes important for regulation of the cell cycle, to suppress COX-2 gene expression and to prevent viral infections. The tumor-selectivity of Wogonin has recently been demonstrated to be due to its ability to differentially modulate the oxidation-reduction status of malignant vs. normal lymphocytic cells and to preferentially induce phospholipase C gamma 1, a key enzyme involved in Ca(2+) signaling, through H(2)O(2) signaling in malignant lymphocytes. This review is aimed to summarize the research results obtained since the last 20 years and to highlight the recently discovered molecular mechanisms.