RESUMEN
We have developed a novel, to our knowledge, in vitro instrument that can deliver intermediate-frequency (100-400 kHz), moderate-intensity (up to and exceeding 6.5 V/cm pk-pk) electric fields (EFs) to cell and tissue cultures generated using induced electromagnetic fields (EMFs) in an air-core solenoid coil. A major application of these EFs is as an emerging cancer treatment modality. In vitro studies by Novocure reported that intermediate-frequency (100-300 kHz), low-amplitude (1-3 V/cm) EFs, which they called "tumor-treating fields (TTFields)," had an antimitotic effect on glioblastoma multiforme (GBM) cells. The effect was found to increase with increasing EF amplitude. Despite continued theoretical, preclinical, and clinical study, the mechanism of action remains incompletely understood. All previous in vitro studies of "TTFields" have used attached, capacitively coupled electrodes to deliver alternating EFs to cell and tissue cultures. This contacting delivery method suffers from a poorly characterized EF profile and conductive heating that limits the duration and amplitude of the applied EFs. In contrast, our device delivers EFs with a well-characterized radial profile in a noncontacting manner, eliminating conductive heating and enabling thermally regulated EF delivery. To test and demonstrate our system, we generated continuous, 200-kHz EMF with an EF amplitude profile spanning 0-6.5 V/cm pk-pk and applied them to exemplar human thyroid cell cultures for 72 h. We observed moderate reduction in cell density (<10%) at low EF amplitudes (<4 V/cm) and a greater reduction in cell density of up to 25% at higher amplitudes (4-6.5 V/cm). Our device can be readily extended to other EF frequency and amplitude regimes. Future studies with this device should contribute to the ongoing debate about the efficacy and mechanism(s) of action of "TTFields" by better isolating the effects of EFs and providing access to previously inaccessible EF regimes.
Asunto(s)
Terapia por Estimulación Eléctrica , Glioblastoma , Conductividad Eléctrica , Campos Electromagnéticos , Glioblastoma/terapia , HumanosRESUMEN
Purpose: Glioblastoma (GBM) is highly resistant to treatment, largely due to disease heterogeneity and resistance mechanisms. We sought to investigate a promising drug that can inhibit multiple aspects of cancer cell survival mechanisms and become an effective therapeutic for GBM patients.Experimental Design: To investigate TG02, an agent with known penetration of the blood-brain barrier, we examined the effects as single agent and in combination with temozolomide, a commonly used chemotherapy in GBM. We used human GBM cells and a syngeneic mouse orthotopic GBM model, evaluating survival and the pharmacodynamics of TG02. Mechanistic studies included TG02-induced transcriptional regulation, apoptosis, and RNA sequencing in treated GBM cells as well as the investigation of mitochondrial and glycolytic function assays.Results: We demonstrated that TG02 inhibited cell proliferation, induced cell death, and synergized with temozolomide in GBM cells with different genetic background but not in astrocytes. TG02-induced cytotoxicity was blocked by the overexpression of phosphorylated CDK9, suggesting a CDK9-dependent cell killing. TG02 suppressed transcriptional progression of antiapoptotic proteins and induced apoptosis in GBM cells. We further demonstrated that TG02 caused mitochondrial dysfunction and glycolytic suppression and ultimately ATP depletion in GBM. A prolonged survival was observed in GBM mice receiving combined treatment of TG02 and temozolomide. The TG02-induced decrease of CDK9 phosphorylation was confirmed in the brain tumor tissue.Conclusions: TG02 inhibits multiple survival mechanisms and synergistically decreases energy production with temozolomide, representing a promising therapeutic strategy in GBM, currently under investigation in an ongoing clinical trial. Clin Cancer Res; 24(5); 1124-37. ©2017 AACR.
Asunto(s)
Protocolos de Quimioterapia Combinada Antineoplásica/farmacología , Neoplasias Encefálicas/tratamiento farmacológico , Glioblastoma/tratamiento farmacológico , Compuestos Heterocíclicos de 4 o más Anillos/farmacología , Transcripción Genética/efectos de los fármacos , Animales , Protocolos de Quimioterapia Combinada Antineoplásica/uso terapéutico , Apoptosis/efectos de los fármacos , Encéfalo/efectos de los fármacos , Encéfalo/metabolismo , Encéfalo/patología , Neoplasias Encefálicas/genética , Neoplasias Encefálicas/metabolismo , Neoplasias Encefálicas/patología , Línea Celular Tumoral/trasplante , Proliferación Celular/efectos de los fármacos , Modelos Animales de Enfermedad , Evaluación Preclínica de Medicamentos , Sinergismo Farmacológico , Metabolismo Energético/efectos de los fármacos , Glioblastoma/genética , Glioblastoma/metabolismo , Glioblastoma/patología , Compuestos Heterocíclicos de 4 o más Anillos/uso terapéutico , Humanos , Ratones , Ratones Endogámicos C57BL , Temozolomida/farmacología , Temozolomida/uso terapéuticoRESUMEN
Metabolomics has shown significant potential in identifying small molecules specific to tumor phenotypes. In this study we analyzed resected tissue metabolites using capillary electrophoresis-mass spectrometry and found that tissue hypotaurine levels strongly and positively correlated with glioma grade. In vitro studies were conducted to show that hypotaurine activates hypoxia signaling through the competitive inhibition of prolyl hydroxylase domain-2. This leads to the activation of hypoxia signaling as well as to the enhancement of glioma cell proliferation and invasion. In contrast, taurine, the oxidation metabolite of hypotaurine, decreased intracellular hypotaurine and resulted in glioma cell growth arrest. Lastly, a glioblastoma xenograft mice model was supplemented with taurine feed and exhibited impaired tumor growth. Taken together, these findings suggest that hypotaurine is an aberrantly produced oncometabolite, mediating tumor molecular pathophysiology and progression. The hypotaurine metabolic pathway may provide a potentially new target for glioblastoma diagnosis and therapy.
Asunto(s)
Encéfalo/patología , Glioma/patología , Hipoxia/fisiopatología , Metabolómica , Transducción de Señal , Taurina/análogos & derivados , Animales , Apoptosis , Encéfalo/metabolismo , Estudios de Casos y Controles , Ciclo Celular , Proliferación Celular , Estudios de Seguimiento , Glioma/metabolismo , Humanos , Ratones , Ratones Endogámicos BALB C , Ratones Desnudos , Fenotipo , Pronóstico , Taurina/metabolismo , Células Tumorales Cultivadas , Ensayos Antitumor por Modelo de XenoinjertoRESUMEN
Protein phosphatase 2A (PP2A) is a serine/threonine phosphatase that plays a significant role in mitotic progression and cellular responses to DNA damage. While traditionally viewed as a tumor suppressor, inhibition of PP2A has recently come to attention as a novel therapeutic means of driving senescent cancer cells into mitosis and promoting cell death via mitotic catastrophe. These findings have been corroborated in numerous studies utilizing naturally produced compounds that selectively inhibit PP2A. To overcome the known human toxicities associated with these compounds, a water-soluble small molecule inhibitor, LB100, was recently developed to competitively inhibit the PP2A protein. This review summarizes the pre-clinical studies to date that have demonstrated the anti-cancer activity of LB100 via its chemo- and radio-sensitizing properties. These studies demonstrate the tremendous therapeutic potential of LB100 in a variety of cancer types. The results of an ongoing phase 1 trial are eagerly anticipated.
Asunto(s)
Antineoplásicos/farmacología , Compuestos Bicíclicos Heterocíclicos con Puentes/farmacología , Inhibidores Enzimáticos/farmacología , Piperazinas/farmacología , Proteína Fosfatasa 2/antagonistas & inhibidores , Fármacos Sensibilizantes a Radiaciones/farmacología , Animales , Apoptosis/efectos de los fármacos , Ciclo Celular/efectos de los fármacos , Evaluación Preclínica de Medicamentos , Resistencia a Antineoplásicos , Humanos , Mitosis/efectos de los fármacos , Mitosis/genética , Neoplasias/tratamiento farmacológico , Neoplasias/genética , Neoplasias/metabolismo , Proteínas Oncogénicas/antagonistas & inhibidores , Proteínas Oncogénicas/genética , Proteínas Oncogénicas/metabolismo , Proteína Fosfatasa 2/genética , Proteína Fosfatasa 2/metabolismo , Proteína Tumoral Controlada Traslacionalmente 1 , Proteínas Supresoras de Tumor/antagonistas & inhibidores , Proteínas Supresoras de Tumor/genética , Proteínas Supresoras de Tumor/metabolismo , Vía de Señalización Wnt/efectos de los fármacosRESUMEN
Gaucher disease is caused by mutations in the glucosidase, beta, acid gene that encodes glucocerebrosidase (GCase). Glucosidase, beta, acid mutations often cause protein misfolding and quantitative loss of GCase. In the present study, we found that celastrol, an herb derivative with known anticancer, anti-inflammatory, and antioxidant activity, significantly increased the quantity and catalytic activity of GCase. Celastrol interfered with the establishment of the heat-shock protein 90/Hsp90 cochaperone Cdc37/Hsp90-Hsp70-organizing protein chaperone complex with mutant GCase and reduced heat-shock protein 90-associated protein degradation. In addition, celastrol modulated the expression of molecular chaperones. Bcl2-associated athanogene 3 and heat shock 70kDa proteins 1A and 1B were significantly increased by celastrol. Furthermore, BAG family molecular chaperone regulator 3 assisted protein folding and maturation of mutant GCase. These findings provide insight into a therapeutic strategy for Gaucher disease and other human disorders that are associated with protein misfolding.
Asunto(s)
Enfermedad de Gaucher/metabolismo , Glucosilceramidasa/metabolismo , Chaperonas Moleculares/química , Triterpenos/farmacología , Proteínas Adaptadoras Transductoras de Señales/metabolismo , Proteínas Reguladoras de la Apoptosis , Catálisis , Proteínas de Ciclo Celular/metabolismo , Chaperoninas/metabolismo , Fibroblastos/metabolismo , Enfermedad de Gaucher/genética , Regulación Enzimológica de la Expresión Génica/efectos de los fármacos , Glucosilceramidasa/genética , Proteínas HSP70 de Choque Térmico/metabolismo , Proteínas HSP90 de Choque Térmico/metabolismo , Células HeLa , Humanos , Mutación , Triterpenos Pentacíclicos , Preparaciones de Plantas/farmacología , Unión Proteica , Desnaturalización Proteica , Pliegue de Proteína , Interferencia de ARN , Reacción en Cadena en Tiempo Real de la PolimerasaRESUMEN
BACKGROUND: The failure of cytotoxic cancer regimens to cure the most drug-resistant, well-differentiated solid tumors has been attributed to the heterogeneity of cell types that differ in their capacities for growth, differentiation, and metastases. We investigated the effect of LB1, a small molecule inhibitor of serine/threonine protein phosphatase 2A (PP2A), on its ability to inhibit a low growth fraction and highly drug-resistant solid neuroendocrine tumor, such as metastatic pheochromocytoma (PHEO). Subsequently, we evaluated the increased efficacy of chemotherapy combined with LB1. METHODOLOGY/PRINCIPAL FINDINGS: The effect of LB1 and temozolomide (TMZ), a standard chemotherapeutic agent that alone only transiently suppressed the growth and regression of metastatic PHEO, was evaluated in vitro on a single PHEO cell line and in vivo on mouse model of metastatic PHEO. In the present study, we show that metastatic PHEO, for which there is currently no cure, can be eliminated by combining LB1, thereby inhibiting PP2A, with TMZ. This new treatment approach resulted in long term, disease-free survival of up to 40% of animals bearing multiple intrahepatic metastases, a disease state that the majority of patients die from. Inhibition of PP2A was associated with prevention of G1/S phase arrest by p53 and of mitotic arrest mediated by polo-like kinase 1 (Plk-1). CONCLUSIONS/SIGNIFICANCE: The elimination of DNA damage-induced defense mechanisms, through transient pharmacologic inhibition of PP2A, is proposed as a new approach for enhancing the efficacy of non-specific cancer chemotherapy regimens against a broad spectrum of low growth fraction tumors very commonly resistant to cytotoxic drugs.