RESUMO
We used a probabilistic reversal learning task to examine prediction error-driven belief updating in three clinical groups with psychosis or psychosis-like symptoms. Study 1 compared people with at-risk mental state and first episode psychosis (FEP) to matched controls. Study 2 compared people diagnosed with treatment-resistant schizophrenia (TRS) to matched controls. The design replicated our previous work showing ketamine-related perturbations in how meta-level confidence maintained behavioural policy. We applied the same computational modelling analysis here, in order to compare the pharmacological model to three groups at different stages of psychosis. Accuracy was reduced in FEP, reflecting increased tendencies to shift strategy following probabilistic errors. The TRS group also showed a greater tendency to shift choice strategies though accuracy levels were not significantly reduced. Applying the previously-used computational modelling approach, we observed that only the TRS group showed altered confidence-based modulation of responding, previously observed under ketamine administration. Overall, our behavioural findings demonstrated resemblance between clinical groups (FEP and TRS) and ketamine in terms of a reduction in stabilisation of responding in a noisy environment. The computational analysis suggested that TRS, but not FEP, replicates ketamine effects but we consider the computational findings preliminary given limitations in performance of the model.
Assuntos
Ketamina , Transtornos Psicóticos , Reversão de Aprendizagem , Esquizofrenia , Humanos , Esquizofrenia/fisiopatologia , Esquizofrenia/tratamento farmacológico , Transtornos Psicóticos/tratamento farmacológico , Transtornos Psicóticos/fisiopatologia , Transtornos Psicóticos/psicologia , Masculino , Feminino , Adulto , Reversão de Aprendizagem/fisiologia , Adulto Jovem , Adolescente , Psicologia do Esquizofrênico , Estudos de Casos e ControlesRESUMO
Recent theories of cortical function construe the brain as performing hierarchical Bayesian inference. According to these theories, the precision of prediction errors plays a key role in learning and decision-making, is controlled by dopamine and contributes to the pathogenesis of psychosis. To test these hypotheses, we studied learning with variable outcome-precision in healthy individuals after dopaminergic modulation with a placebo, a dopamine receptor agonist bromocriptine or a dopamine receptor antagonist sulpiride (dopamine study n = 59) and in patients with early psychosis (psychosis study n = 74: 20 participants with first-episode psychosis, 30 healthy controls and 24 participants with at-risk mental state attenuated psychotic symptoms). Behavioural computational modelling indicated that precision weighting of prediction errors benefits learning in health and is impaired in psychosis. FMRI revealed coding of unsigned prediction errors, which signal surprise, relative to their precision in superior frontal cortex (replicated across studies, combined n = 133), which was perturbed by dopaminergic modulation, impaired in psychosis and associated with task performance and schizotypy (schizotypy correlation in 86 healthy volunteers). In contrast to our previous work, we did not observe significant precision-weighting of signed prediction errors, which signal valence, in the midbrain and ventral striatum in the healthy controls (or patients) in the psychosis study. We conclude that healthy people, but not patients with first-episode psychosis, take into account the precision of the environment when updating beliefs. Precision weighting of cortical prediction error signals is a key mechanism through which dopamine modulates inference and contributes to the pathogenesis of psychosis.
Assuntos
Dopamina , Transtornos Psicóticos , Teorema de Bayes , Encéfalo , Humanos , Aprendizagem , Imageamento por Ressonância Magnética , RecompensaRESUMO
A correction to this paper has been published and can be accessed via a link at the top of the paper.
Assuntos
Antineoplásicos/farmacologia , Regulação Leucêmica da Expressão Gênica , Inibidores de Proteínas Quinases/farmacologia , Pirazóis/farmacologia , Pirimidinas/farmacologia , Tirosina Quinase 3 Semelhante a fms/antagonistas & inibidores , Adenina/análogos & derivados , Tirosina Quinase da Agamaglobulinemia , Apoptose/efeitos dos fármacos , Benzamidas/farmacologia , Compostos Bicíclicos Heterocíclicos com Pontes/farmacologia , Linhagem Celular Tumoral , Pontos de Checagem da Fase G1 do Ciclo Celular/efeitos dos fármacos , Humanos , Leucemia Mieloide Aguda/enzimologia , Leucemia Mieloide Aguda/genética , Leucemia Mieloide Aguda/patologia , Terapia de Alvo Molecular , Especificidade de Órgãos , Fosforilação/efeitos dos fármacos , Piperidinas , Proteínas Tirosina Quinases/antagonistas & inibidores , Proteínas Tirosina Quinases/genética , Proteínas Tirosina Quinases/metabolismo , Proteínas Proto-Oncogênicas c-akt/antagonistas & inibidores , Proteínas Proto-Oncogênicas c-akt/genética , Proteínas Proto-Oncogênicas c-akt/metabolismo , Fator de Transcrição STAT5/antagonistas & inibidores , Fator de Transcrição STAT5/genética , Fator de Transcrição STAT5/metabolismo , Transdução de Sinais , Tirosina Quinase 3 Semelhante a fms/genética , Tirosina Quinase 3 Semelhante a fms/metabolismoRESUMO
Bruton's tyrosine kinase (BTK) kinase is a member of the TEC kinase family and is a key regulator of the B-cell receptor (BCR)-mediated signaling pathway. It is important for B-cell maturation, proliferation, survival and metastasis. Pharmacological inhibition of BTK is clinically effective against a variety of B-cell malignances, such as mantle cell lymphoma, chronic lymphocytic leukemia (CLL), acute myeloid leukemia (AML) and activated B-cell-diffuse large B-cell lymphoma. MNK kinase is one of the key downstream regulators in the RAF-MEK-ERK signaling pathway and controls protein synthesis via regulating the activity of eIF4E. Inhibition of MNK activity has been observed to moderately inhibit the proliferation of AML cells. Through a structure-based drug-design approach, we have discovered a selective and potent BTK/MNK dual kinase inhibitor (QL-X-138), which exhibits covalent binding to BTK and noncovalent binding to MNK. Compared with the BTK kinase inhibitor (PCI-32765) and the MNK kinase inhibitor (cercosporamide), QL-X-138 enhanced the antiproliferative efficacies in vitro against a variety of B-cell cancer cell lines, as well as AML and CLL primary patient cells, which respond moderately to BTK inhibitor in vitro. The agent can effectively arrest the growth of lymphoma and leukemia cells at the G0-G1 stage and can induce strong apoptotic cell death. These primary results demonstrate that simultaneous inhibition of BTK and MNK kinase activity might be a new therapeutic strategy for B-cell malignances.
Assuntos
Peptídeos e Proteínas de Sinalização Intracelular/antagonistas & inibidores , Leucemia/tratamento farmacológico , Linfoma/tratamento farmacológico , Inibidores de Proteínas Quinases/uso terapêutico , Proteínas Serina-Treonina Quinases/antagonistas & inibidores , Proteínas Tirosina Quinases/antagonistas & inibidores , Tirosina Quinase da Agamaglobulinemia , Ciclo Celular/efeitos dos fármacos , Linhagem Celular Tumoral , Proliferação de Células/efeitos dos fármacos , Desenho de Fármacos , Humanos , Leucemia/patologia , Linfoma/patologiaRESUMO
Salivary gland tumors (SGT) are a group of highly heterogeneous head and neck malignancies with widely varied clinical outcomes and no standard effective treatments. The CRTC1-MAML2 fusion oncogene, encoded by a recurring chromosomal translocation t(11;19)(q14-21;p12-13), is a frequent genetic alteration found in >50% of mucoepidermoid carcinomas (MEC), the most common malignant SGT. In this study, we aimed to define the role of the CRTC1-MAML2 oncogene in the maintenance of MEC tumor growth and to investigate critical downstream target genes and pathways for therapeutic targeting of MEC. By performing gene expression analyses and functional studies via RNA interference and pharmacological modulation, we determined the importance of the CRTC1-MAML2 fusion gene and its downstream AREG-EGFR signaling in human MEC cancer cell growth and survival in vitro and in vivo using human MEC xenograft models. We found that CRTC1-MAML2 fusion oncogene was required for the growth and survival of fusion-positive human MEC cancer cells in vitro and in vivo. The CRTC1-MAML2 oncoprotein induced the upregulation of the epidermal growth factor receptor (EGFR) ligand Amphiregulin (AREG) by co-activating the transcription factor CREB, and AREG subsequently activated EGFR signaling in an autocrine manner that promoted MEC cell growth and survival. Importantly, CRTC1-MAML2-positive MEC cells were highly sensitive to EGFR signaling inhibition. Therefore, our study revealed that aberrantly activated AREG-EGFR signaling is required for CRTC1-MAML2-positive MEC cell growth and survival, suggesting that EGFR-targeted therapies will benefit patients with advanced, unresectable CRTC1-MAML2-positive MEC.
Assuntos
Carcinoma Mucoepidermoide/genética , Carcinoma Mucoepidermoide/metabolismo , Proteínas de Ligação a DNA/genética , Receptores ErbB/metabolismo , Glicoproteínas/metabolismo , Peptídeos e Proteínas de Sinalização Intercelular/metabolismo , Proteínas Nucleares/genética , Proteínas de Fusão Oncogênica/genética , Transdução de Sinais , Fatores de Transcrição/genética , Anfirregulina , Animais , Anticorpos Monoclonais Humanizados/farmacologia , Linhagem Celular Tumoral , Proliferação de Células/efeitos dos fármacos , Sobrevivência Celular/efeitos dos fármacos , Sobrevivência Celular/genética , Cetuximab , Cromossomos Humanos Par 11 , Cromossomos Humanos Par 19 , Proteína de Ligação ao Elemento de Resposta ao AMP Cíclico/metabolismo , Modelos Animais de Doenças , Família de Proteínas EGF , Receptores ErbB/antagonistas & inibidores , Feminino , Regulação Neoplásica da Expressão Gênica , Glicoproteínas/genética , Xenoenxertos , Humanos , Peptídeos e Proteínas de Sinalização Intercelular/genética , Proteínas de Fusão Oncogênica/metabolismo , Ligação Proteica , Transdução de Sinais/efeitos dos fármacos , Transativadores , Ativação Transcricional , Translocação GenéticaRESUMO
Acute myeloid leukemia (AML) progenitors are frequently characterized by activating mutations in the receptor tyrosine kinase Fms-like tyrosine kinase-3 (FLT3). Protein tyrosine kinases are integral components of signaling cascades that have a role in both FLT3-mediated transformation as well as viability pathways that are advantageous to leukemic cell survival. The bone marrow microenvironment can diminish AML sensitivity to tyrosine kinase inhibitors. We hypothesized that inhibition of protein kinases in addition to FLT3 may be effective in overriding drug resistance in AML. We used a cell-based model mimicking stromal protection as part of an unbiased high-throughput chemical screen to identify kinase inhibitors with the potential to override microenvironment-mediated drug resistance in mutant FLT3-positive AML. Several related multi-targeted kinase inhibitors, including dasatinib, with the capability of reversing microenvironment-induced resistance to FLT3 inhibition were identified and validated. We validated synergy in vitro and demonstrated effective combination potential in vivo. In particular Janus kinase inhibitors were effective in overriding stromal protection and potentiating FLT3 inhibition in primary AML and cell lines. These results hint at a novel concept of using combination therapy to override drug resistance in mutant FLT3-positive AML in the bone marrow niche and suppress or eradicate residual disease.
Assuntos
Protocolos de Quimioterapia Combinada Antineoplásica/uso terapêutico , Janus Quinases/antagonistas & inibidores , Leucemia Mieloide Aguda/tratamento farmacológico , Mutação , Inibidores de Proteínas Quinases/administração & dosagem , Tirosina Quinase 3 Semelhante a fms/genética , Animais , Dasatinibe , Resistencia a Medicamentos Antineoplásicos , Humanos , Leucemia Mieloide Aguda/genética , Leucemia Mieloide Aguda/metabolismo , Camundongos , Pirimidinas/administração & dosagem , Fator de Transcrição STAT5/metabolismo , Estaurosporina/administração & dosagem , Estaurosporina/análogos & derivados , Células Estromais/fisiologia , Tiazóis/administração & dosagem , Tirosina Quinase 3 Semelhante a fms/antagonistas & inibidoresRESUMO
Myeloproliferative neoplasms are characterized by overproduction of myeloid lineage cells with frequent acquisition of oncogenic JAK2V617F kinase mutations. The molecular mechanisms that regulate energy requirements in these diseases are poorly understood. Transformed cells tend to rely on fermentation instead of more efficient oxidative phosphorylation for energy production. Our data in JAK2V617F-transformed cells show that growth and metabolic activity were strictly dependent on the presence of glucose. Uptake of glucose and cell surface expression of the glucose transporter Glut1 required the oncogenic tyrosine kinase. Importantly, JAK2V617F as well as active STAT5 increased the expression of the inducible rate-limiting enzyme 6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase 3 (PFKFB3), which controls glycolytic flux through 6-phosphofructo-1-kinase. PFKFB3 was required for JAK2V617F-dependent lactate production, oxidative metabolic activity and glucose uptake. Targeted knockdown of PFKFB3 also limited cell growth under normoxic and hypoxic conditions and blocked in vivo tumor formation in mice. Overall, these data suggest that inducible PFKFB3 is required for increased growth, metabolic activity and is regulated through active JAK2 and STAT5. Novel therapies that specifically block PFKFB3 activity or expression would, therefore, be expected to inhibit JAK2/STAT5-dependent malignancies and related cancers.
Assuntos
Frutose-Bifosfatase/genética , Frutose-Bifosfatase/metabolismo , Janus Quinase 2/genética , Janus Quinase 2/metabolismo , Fosfofrutoquinase-2/genética , Animais , Linhagem Celular Tumoral , Proliferação de Células , Transformação Celular Neoplásica/genética , Feminino , Glucose/metabolismo , Transportador de Glucose Tipo 1/genética , Transportador de Glucose Tipo 1/metabolismo , Humanos , Camundongos , Camundongos SCID , Fosfofrutoquinase-2/metabolismo , Fator de Transcrição STAT5/metabolismo , Ensaios Antitumorais Modelo de XenoenxertoRESUMO
The transforming JAK2V617F kinase is frequently associated with myeloproliferative neoplasms and thought to be instrumental for the overproduction of myeloid lineage cells. Several small molecule drugs targeting JAK2 are currently in clinical development for treatment in these diseases. We performed a high-throughput in vitro screen to identify point mutations in JAK2V617F that would be predicted to have potential clinical relevance and associated with drug resistance to the JAK2 inhibitor ruxolitinib (INCB018424). Seven libraries of mutagenized JAK2V617F cDNA were screened to specifically identify mutations in the predicted drug-binding region that would confer resistance to ruxolitinib, using a BaF3 cell-based assay. We identified five different non-synonymous point mutations that conferred drug resistance. Cells containing mutations had a 9- to 33-fold higher EC(50) for ruxolitinib compared with native JAK2V617F. Our results further indicated that these mutations also conferred cross-resistance to all JAK2 kinase inhibitors tested, including AZD1480, TG101348, lestaurtinib (CEP-701) and CYT-387. Surprisingly, introduction of the 'gatekeeper' mutation (M929I) in JAK2V617F affected only ruxolitinib sensitivity (fourfold increase in EC(50)). These results suggest that JAK2 inhibitors currently in clinical trials may be prone to resistance as a result of point mutations and caution should be exercised when administering these drugs.
Assuntos
Janus Quinase 2/genética , Transtornos Mieloproliferativos/tratamento farmacológico , Transtornos Mieloproliferativos/genética , Mutação Puntual , Inibidores de Proteínas Quinases/uso terapêutico , Pirazóis/uso terapêutico , Animais , Resistencia a Medicamentos Antineoplásicos , Ensaios de Triagem em Larga Escala , Humanos , Janus Quinase 2/antagonistas & inibidores , Janus Quinase 2/química , Camundongos , Nitrilas , Estrutura Terciária de Proteína , PirimidinasRESUMO
Drug resistance is a growing area of concern. It has been shown that a small, residual pool of leukemic CD34+ progenitor cells can survive in the marrow microenvironment of chronic myeloid leukemia (CML) patients after years of kinase inhibitor treatment. Bone marrow (BM) stroma has been implicated in the long-term survival of leukemic cells, and contributes to the expansion and proliferation of both transformed and normal hematopoietic cells. Mechanistically, we found that CML cells expressed CXCR4, and that plerixafor diminished BCR-ABL-positive cell migration and reduced adhesion of these cells to extra cellular-matrix components and to BM stromal cells in vitro. Moreover, plerixafor decreased the drug resistance of CML cells induced by co-culture with BM stromal cells in vitro. Using a functional mouse model of progressive and residual disease, we demonstrated the ability of the CXCR4 inhibitor, plerixafor, to mobilize leukemic cells in vivo, such that a plerixafor-nilotinib combination reduced the leukemia burden in mice significantly below the baseline level suppression exhibited by a moderate-to-high dose of nilotinib as single agent. These results support the idea of using CXCR4 inhibition in conjunction with targeted tyrosine kinase inhibition to override drug resistance in CML and suppress or eradicate residual disease.
Assuntos
Antineoplásicos/uso terapêutico , Células da Medula Óssea/efeitos dos fármacos , Leucemia Mielogênica Crônica BCR-ABL Positiva/tratamento farmacológico , Pirimidinas/uso terapêutico , Receptores CXCR4/antagonistas & inibidores , Células Estromais/efeitos dos fármacos , Animais , Benzilaminas , Células da Medula Óssea/metabolismo , Células da Medula Óssea/patologia , Adesão Celular , Linhagem Celular Tumoral , Proliferação de Células , Técnicas de Cocultura , Ciclamos , Resistencia a Medicamentos Antineoplásicos , Citometria de Fluxo , Compostos Heterocíclicos/farmacologia , Humanos , Leucemia Mielogênica Crônica BCR-ABL Positiva/patologia , Camundongos , Células Estromais/metabolismo , Células Estromais/patologiaRESUMO
Transformation by tyrosine kinase oncogenes (TKOs) in myeloid malignancies, including BCR-ABL in chronic myeloid leukemia, FLT3ITD in acute myeloid leukemia or JAK2V617F in myeloproliferative neoplasms, is associated with increased growth and cytoskeletal abnormalities. Using targeted approaches against components of the superoxide-producing NADPH-oxidases, including NADPH oxidase 2 (NOX2), NOX4 and the common p22(phox) subunit of NOX1-4, myeloid cells were found to display reduced cell growth and spontaneous migration. Consistent with a role of NOXs as regulators of membrane proximal signaling events in nonphagocytic cells, NOX2 and NOX4 were not involved in the excess production of intracellular reactive oxygen species and did not significantly increase oxygen consumption. All NOX family members are controlled in part through levels of the rate-limiting substrate NADPH, which was found to be significantly elevated in TKO-transformed cells. Also, reduced phosphorylation of the actin filament crosslinking protein myristoylated alanine-rich C-kinase substrate (MARCKS) in response to suppression of p22(phox) hints at a novel effector of NOX signaling. MARCKS was also found to be required for increased migration. Overall, these data suggest a model whereby NOX links metabolic NADPH production to cellular events that directly contribute to transformation.
Assuntos
Movimento Celular , Proliferação de Células , Transformação Celular Neoplásica , Células Mieloides/patologia , NADPH Oxidases/fisiologia , Proteínas Tirosina Quinases/genética , Animais , Linhagem Celular , Humanos , Leucemia Mieloide/etiologia , Leucemia Mieloide/patologia , Camundongos , NADP/biossíntese , OncogenesRESUMO
Drug resistance is a growing concern with clinical use of tyrosine kinase inhibitors. Utilizing in vitro models of intrinsic drug resistance and stromal-mediated chemoresistance, as well as functional mouse models of progressive and residual disease, we attempted to develop a potential therapeutic approach designed to suppress leukemia recurrence following treatment with selective kinase inhibitors. The novel IAP inhibitor, LCL161, [corrected] was observed to potentiate the effects of tyrosine kinase inhibition against leukemic disease both in the absence and presence of a stromal-protected [corrected] environment. LCL161 enhanced the proapoptotic effects of nilotinib and PKC412, against leukemic disease in vitro and potentiated the activity of both kinase inhibitors against leukemic disease in vivo. In addition, LCL161 synergized in vivo with nilotinib to reduce leukemia burden significantly below the baseline level suppression exhibited by a moderate-to-high dose of nilotinib. Finally, LCL161 displayed antiproliferative effects against cells characterized by intrinsic resistance to tyrosine kinase inhibitors as a result of expression of point mutations in the protein targets of drug inhibition. These results support the idea of using IAP inhibitors in conjunction with targeted tyrosine kinase inhibition to override drug resistance and suppress or eradicate residual disease.
Assuntos
Proteínas Inibidoras de Apoptose/antagonistas & inibidores , Leucemia/tratamento farmacológico , Inibidores de Proteínas Quinases/uso terapêutico , Tirosina Quinase 3 Semelhante a fms/antagonistas & inibidores , Animais , Linhagem Celular , Proliferação de Células/efeitos dos fármacos , Resistencia a Medicamentos Antineoplásicos , Sinergismo Farmacológico , Humanos , Leucemia/patologia , Camundongos , Proteínas Proto-Oncogênicas c-abl/antagonistas & inibidores , Pirimidinas/uso terapêutico , Estaurosporina/análogos & derivados , Estaurosporina/uso terapêuticoRESUMO
Mutant Fms-Like Tyrosine kinase-3 (FLT3), which is expressed in the leukemic cells of a subpopulation of acute myeloid leukemia (AML) patients, represents an attractive target for the therapy of AML. There are several FLT3 inhibitors presently in clinical trials with sufficient efficacy and toxicity features to warrant further testing in combination with standard therapies. However, the transient and partial responses observed in AML patients treated with FLT3 inhibitors, coupled with the discovery of drug-resistant leukemic blast cells in AML patients, have made resistance to FLT3 inhibitors a growing concern. In this study, we provide an overview of the role of mutant FLT3 in AML, FLT3 inhibitors under clinical and preclinical investigation, mechanisms of resistance to FLT3 inhibitors, and possible therapeutic approaches to overcoming this resistance.
Assuntos
Antineoplásicos/uso terapêutico , Resistencia a Medicamentos Antineoplásicos/genética , Leucemia Mieloide Aguda/genética , Inibidores de Proteínas Quinases/uso terapêutico , Tirosina Quinase 3 Semelhante a fms/genética , Humanos , Leucemia Mieloide Aguda/tratamento farmacológico , Mutação , Transdução de Sinais , Tirosina Quinase 3 Semelhante a fms/antagonistas & inibidoresAssuntos
Protocolos de Quimioterapia Combinada Antineoplásica/farmacologia , Resistencia a Medicamentos Antineoplásicos , Proteínas de Fusão bcr-abl/antagonistas & inibidores , Leucemia Experimental/tratamento farmacológico , Piperazinas/farmacologia , Células Precursoras de Linfócitos B/efeitos dos fármacos , Inibidores de Proteínas Quinases/farmacologia , Pirimidinas/farmacologia , Tiazóis/farmacologia , Trifosfato de Adenosina/metabolismo , Animais , Benzamidas , Células Cultivadas , Sinergismo Farmacológico , Mesilato de Imatinib , Leucemia Experimental/metabolismo , Leucemia Experimental/patologia , Camundongos , Ensaios Antitumorais Modelo de XenoenxertoRESUMO
BACKGROUND: Epithelial-to-mesenchymal transition (EMT) is associated with decreased adhesion and acquisition of metastatic potential of breast cancer cells. Epithelial-to-mesenchymal transition is mediated, in part, by two transcription repressors, Snail and Slug, that are known to be targets of the Notch signaling pathway, and JAGGED1-induced Notch activation increases EMT. However, the events that lead to increased Notch activity during EMT of breast cancer cells are unknown. METHODS: The accumulation of hypoxia inducible factors (HIFs) under hypoxia was detected by western blot analysis, and their effects on Notch signaling were measured by an in vitro Notch reporter assay. The expression of Notch target genes under hypoxia was tested by real-time PCR. The knockdown of HIF-1alpha was mediated by retroviral delivery of shRNA. The expression of Slug and Snail under hypoxia was measured by real-time PCR. Breast cancer cell migration and invasion under hypoxia were tested with cell migration and invasion kits. RESULTS: Hypoxia increased the expression of Notch target genes such as HES1 and HEY1 in breast cancer cells, as was expression of Notch receptors and ligands. The mechanism is likely to involve the accumulation of HIF-1alpha and HIF-2alpha in these cells by hypoxia, which synergised with the Notch co-activator MAML1 in potentiating Notch activity. Hypoxia inducible factor-1alpha was found to bind to HES1 promoter under hypoxia. Knockdown of HIF-1alpha with shRNA inhibited both HES1 and HEY1 expression under hypoxia. Hypoxia increased the expression of Slug and Snail, and decreased the expression of E-cadherin, hallmarks of EMT. Notch pathway inhibition abrogated the hypoxia-mediated increase in Slug and Snail expression, as well as decreased breast cancer cell migration and invasion. CONCLUSION: Hypoxia-mediated Notch signaling may have an important role in the initiation of EMT and subsequent potential for breast cancer metastasis.
Assuntos
Neoplasias da Mama/metabolismo , Caderinas/biossíntese , Movimento Celular/fisiologia , Hipóxia/fisiopatologia , Receptores Notch/biossíntese , Fatores de Transcrição Hélice-Alça-Hélice Básicos/biossíntese , Neoplasias da Mama/fisiopatologia , Proteínas de Ciclo Celular/biossíntese , Feminino , Proteínas de Homeodomínio/biossíntese , Humanos , Invasividade Neoplásica/fisiopatologia , Transdução de Sinais , Fatores de Transcrição HES-1RESUMO
Activating mutations in the NOTCH1 gene have been found in about 60% of patients with T-cell acute lymphoblastic leukemia (T-ALL). In order to study the molecular mechanisms by which altered Notch signaling induces leukemia, a zebrafish model of human NOTCH1-induced T-cell leukemia was generated. Seven of sixteen mosaic fish developed a T-cell lymphoproliferative disease at about 5 months. These neoplastic cells extensively invaded tissues throughout the fish and caused an aggressive and lethal leukemia when transplanted into irradiated recipient fish. However, stable transgenic fish exhibited a longer latency for leukemia onset. When the stable transgenic line was crossed with another line overexpressing the zebrafish bcl2 gene, the leukemia onset was dramatically accelerated, indicating synergy between the Notch pathway and the bcl2-mediated antiapoptotic pathway. Reverse transcription-polymerase chain reaction analysis showed that Notch target genes such as her6 and her9 were highly expressed in NOTCH1-induced leukemias. The ability of this model to detect a strong interaction between NOTCH1 and bcl2 suggests that genetic modifier screens have a high likelihood of revealing other genes that can cooperate with NOTCH1 to induce T-ALL.
Assuntos
Transformação Celular Neoplásica/genética , Leucemia-Linfoma de Células T do Adulto/etiologia , Proteínas Proto-Oncogênicas c-bcl-2/fisiologia , Receptor Notch1/fisiologia , Animais , Animais Geneticamente Modificados , Apoptose , Fatores de Transcrição Hélice-Alça-Hélice Básicos/fisiologia , Feminino , Raios gama , Perfilação da Expressão Gênica , Regulação Leucêmica da Expressão Gênica , Rearranjo Gênico da Cadeia alfa dos Receptores de Antígenos dos Linfócitos T , Genes bcl-2 , Humanos , Leucemia-Linfoma de Células T do Adulto/genética , Masculino , Mosaicismo , Proteínas de Neoplasias/biossíntese , Proteínas de Neoplasias/genética , Proteínas de Neoplasias/fisiologia , Transplante de Neoplasias , Oncogenes , Quimera por Radiação , Tolerância a Radiação , Receptor Notch1/genética , Proteínas Recombinantes de Fusão/fisiologia , Transdução de Sinais , Fatores de Tempo , Peixe-Zebra , Proteínas de Peixe-Zebra/fisiologiaRESUMO
Chronic myelogenous leukaemia (CML) and Philadelphia chromosome positive (Ph+) acute lymphoblastic leukaemia (ALL) are caused by the BCR-ABL oncogene. Imatinib inhibits the tyrosine kinase activity of the BCR-ABL protein and is an effective, frontline therapy for chronic-phase CML. However, accelerated or blast-crisis phase CML patients and Ph+ ALL patients often relapse due to drug resistance resulting from the emergence of imatinib-resistant point mutations within the BCR-ABL tyrosine kinase domain. This has stimulated the development of new kinase inhibitors that are able to over-ride resistance to imatinib. The novel, selective BCR-ABL inhibitor, AMN107, was designed to fit into the ATP-binding site of the BCR-ABL protein with higher affinity than imatinib. In addition to being more potent than imatinib (IC50< 30 nM) against wild-type BCR-ABL, AMN107 is also significantly active against 32/33 imatinib-resistant BCR-ABL mutants. In preclinical studies, AMN107 demonstrated activity in vitro and in vivo against wild-type and imatinib-resistant BCR-ABL-expressing cells. In phase I/II clinical trials, AMN107 has produced haematological and cytogenetic responses in CML patients, who either did not initially respond to imatinib or developed imatinib resistance. Dasatinib (BMS-354825), which inhibits Abl and Src family kinases, is another promising new clinical candidate for CML that has shown good efficacy in CML patients. In this review, the early characterisation and development of AMN107 is discussed, as is the current status of AMN107 in clinical trials for imatinib-resistant CML and Ph+ ALL. Future trends investigating prediction of mechanisms of resistance to AMN107, and how and where AMN107 is expected to fit into the overall picture for treatment of early-phase CML and imatinib-refractory and late-stage disease are discussed.