RESUMEN
Modification of hypothalamic fatty acid (FA) metabolism can improve energy homeostasis and prevent hyperphagia and excessive weight gain in diet-induced obesity (DIO) from a diet high in saturated fatty acids. We have shown previously that C75, a stimulator of carnitine palmitoyl transferase-1 (CPT-1) and fatty acid oxidation (FAOx), exerts at least some of its hypophagic effects via neuronal mechanisms in the hypothalamus. In the present work, we characterized the effects of C75 and another anorexigenic compound, the glycerol-3-phosphate acyltransferase (GPAT) inhibitor FSG67, on FA metabolism, metabolomics profiles, and metabolic stress responses in cultured hypothalamic neurons and hypothalamic neuronal cell lines during lipid excess with palmitate. Both compounds enhanced palmitate oxidation, increased ATP, and inactivated AMP-activated protein kinase (AMPK) in hypothalamic neurons in vitro. Lipidomics and untargeted metabolomics revealed that enhanced catabolism of FA decreased palmitate availability and prevented the production of fatty acylglycerols, ceramides, and cholesterol esters, lipids that are associated with lipotoxicity-provoked metabolic stress. This improved metabolic signature was accompanied by increased levels of reactive oxygen species (ROS), and yet favorable changes in oxidative stress, overt ER stress, and inflammation. We propose that enhancing FAOx in hypothalamic neurons exposed to excess lipids promotes metabolic remodeling that reduces local inflammatory and cell stress responses. This shift would restore mitochondrial function such that increased FAOx can produce hypothalamic neuronal ATP and lead to decreased food intake and body weight to improve systemic metabolism.
Asunto(s)
Hipotálamo/metabolismo , Metaboloma , Palmitatos/metabolismo , Estrés Fisiológico , Sulfonamidas/farmacología , ortoaminobenzoatos/farmacología , 4-Butirolactona/análogos & derivados , 4-Butirolactona/farmacología , Proteínas Quinasas Activadas por AMP/metabolismo , Adenosina Trifosfato/metabolismo , Animales , Depresores del Apetito/farmacología , Línea Celular , Células Cultivadas , Ceramidas/metabolismo , Ésteres del Colesterol/metabolismo , Cricetinae , Glicéridos/metabolismo , Glicerol-3-Fosfato O-Aciltransferasa/antagonistas & inhibidores , Humanos , Hipotálamo/citología , Inflamación/metabolismo , Ratones , Neuronas/metabolismo , Oxidación-Reducción , Especies Reactivas de Oxígeno/metabolismo , Sulfonamidas/química , ortoaminobenzoatos/químicaRESUMEN
Storage of excess calories as triglycerides is central to obesity and its associated disorders. Glycerol-3-phosphate acyltransferases (GPATs) catalyze the initial step in acylglyceride syntheses, including triglyceride synthesis. We utilized a novel small-molecule GPAT inhibitor, FSG67, to investigate metabolic consequences of systemic pharmacological GPAT inhibition in lean and diet-induced obese (DIO) mice. FSG67 administered intraperitoneally decreased body weight and energy intake, without producing conditioned taste aversion. Daily FSG67 (5 mg/kg, 15.3 µmol/kg) produced gradual 12% weight loss in DIO mice beyond that due to transient 9- to 10-day hypophagia (6% weight loss in pair-fed controls). Continued FSG67 maintained the weight loss despite return to baseline energy intake. Weight was lost specifically from fat mass. Indirect calorimetry showed partial protection by FSG67 against decreased rates of oxygen consumption seen with hypophagia. Despite low respiratory exchange ratio due to a high-fat diet, FSG67-treated mice showed further decreased respiratory exchange ratio, beyond pair-fed controls, indicating enhanced fat oxidation. Chronic FSG67 increased glucose tolerance and insulin sensitivity in DIO mice. Chronic FSG67 decreased gene expression for lipogenic enzymes in white adipose tissue and liver and decreased lipid accumulation in white adipose, brown adipose, and liver tissues without signs of damage. RT-PCR showed decreased gene expression for orexigenic hypothalamic neuropeptides AgRP or NPY after acute and chronic systemic FSG67. FSG67 given intracerebroventricularly (100 and 320 nmol icv) produced 24-h weight loss and feeding suppression, indicating contributions from direct central nervous system sites of action. Together, these data point to GPAT as a new potential therapeutic target for the management of obesity and its comorbidities.
Asunto(s)
Adiposidad/fisiología , Ingestión de Alimentos/fisiología , Inhibidores Enzimáticos/farmacología , Glicerol-3-Fosfato O-Aciltransferasa/antagonistas & inhibidores , Resistencia a la Insulina/fisiología , Obesidad/fisiopatología , Adiposidad/efectos de los fármacos , Proteína Relacionada con Agouti/metabolismo , Animales , Grasas de la Dieta/efectos adversos , Modelos Animales de Enfermedad , Relación Dosis-Respuesta a Droga , Ingestión de Alimentos/efectos de los fármacos , Hígado Graso/metabolismo , Hígado Graso/fisiopatología , Glicerol-3-Fosfato O-Aciltransferasa/fisiología , Ratones , Ratones Endogámicos , Mitocondrias Hepáticas/efectos de los fármacos , Mitocondrias Hepáticas/enzimología , Neuropéptido Y/metabolismo , Obesidad/etiología , Obesidad/metabolismo , Consumo de Oxígeno/efectos de los fármacos , Consumo de Oxígeno/fisiología , Delgadez/metabolismo , Delgadez/fisiopatología , Triglicéridos/metabolismoRESUMEN
Our previous reports demonstrated that NAC1, a BTB/POZ domain-containing nuclear protein, upregulates in recurrent ovarian serous carcinoma and participates in developing drug resistance in cancer cells. The current study applies quantitative proteomics to identify the proteins controlled by NAC1 by comparing the proteomes of SKOV3 cells with and without expression of a dominant negative NAC1 construct, N130. From the proteins that are downregulated by N130 (upregulated by NAC1), we chose to further characterize fatty acid synthase (FASN). Similar to change in protein level, the FASN transcript level in SKOV3 cells was significantly reduced by N130 induction or by NAC1 knockdown. Immunohistochemistry showed that NAC1 and FASN immunointensities in ovarian serous carcinoma tissues had a highly significant correlation (P < .0001). Moreover, we found that recurrent serous carcinomas exhibited higher FASN immunointensities than their matched primary tumors (P < .001). Multivariate analysis showed that an FASN staining score of >1 in serous carcinomas was associated with a worse overall survival time (P < .01). Finally, C93, a new FASN inhibitor, induced massive apoptosis in carboplatin/paclitaxel resistant ovarian cancer cells. In conclusion, we show that NAC1 is essential for FASN expression in ovarian serous carcinomas and the expression of FASN significantly correlates with tumor recurrence and disease aggressiveness. The dependence of drug resistant tumor cells on FASN suggests a potential application of FASN-based therapeutics for recurrent ovarian cancer patients.
RESUMEN
Fatty acid synthase (FASN) is an emerging tumor-associated marker and a promising antitumor therapeutic target. In this study, we analyzed the expression of FASN in normal and molar placentas, as well as gestational trophoblastic neoplasia, and assessed the effects of a new FASN inhibitor, C93, on cellular proliferation and apoptosis in choriocarcinoma cells. Using a FASN-specific monoclonal antibody, we found that FASN immunoreactivity was detected in the cytotrophoblast and intermediate (extravillous) trophoblast of normal and molar placentas, as well as in placental site nodules. All choriocarcinomas (n = 33), 90% of epithelioid trophoblastic tumors (n = 20), and 60% of placental site trophoblastic tumors (n = 10) exhibited FASN positivity. FASN expression was further confirmed in vitro by Western blot and real-time PCR. Treatment of JEG3 and JAR cells with C93 induced significant apoptosis through the caspase-3/caspase-9/poly(ADP)ribose polymerase pathway. Cell cycle progression was not affected by the inhibitor. In summary, the data indicate that FASN is expressed in the majority of gestational trophoblastic neoplasias, and is essential for choriocarcinoma cells to survive and escape from apoptosis. FASN inhibitors such as C93 warrant further investigation as targeted therapeutic agents for metastatic and chemoresistant gestational trophoblastic neoplasia.
Asunto(s)
Antineoplásicos/farmacología , Inhibidores Enzimáticos/farmacología , Ácido Graso Sintasas/biosíntesis , Neoplasias Trofoblásticas/enzimología , Neoplasias Uterinas/enzimología , Apoptosis/efectos de los fármacos , Western Blotting , Separación Celular , Supervivencia Celular/efectos de los fármacos , Ácido Graso Sintasas/antagonistas & inhibidores , Femenino , Citometría de Flujo , Humanos , Mola Hidatiforme/enzimología , Inmunohistoquímica , Placenta/enzimología , Embarazo , Reacción en Cadena de la Polimerasa de Transcriptasa InversaRESUMEN
Central and intraperitoneal C75, an inhibitor of fatty acid synthase and stimulator of carnitine palmitoyl-transferase-1, inhibits eating in mice and rats. Mechanisms involved in feeding inhibition after central C75 have been identified, but little is yet known about how systemic C75 might inhibit eating. One issue is whether intraperitoneal C75 reduces food intake in rats by influencing normal physiological controls of food intake or acts nonselectively, for example by eliciting illness or aversion. Another issue relates to whether intraperitoneal C75 acts centrally or, similar to some other peripheral metabolic controls of eating, activates abdominal vagal afferents to inhibit eating. To further address these questions, we investigated the effects of intraperitoneal C75 on spontaneous meal patterns and the formation of conditioned taste aversion (CTA). We also tested whether the eating inhibitory effect of intraperitoneal C75 is vagally mediated by testing rats after either total subdiaphragmatic vagotomy (TVX) or selective subdiaphragmatic vagal deafferentations (SDA). Intraperitoneal injection of 3.2 and 7.5 mg/kg of C75 significantly reduced food intake 3, 12, and 24 h after injection by reducing the number of meals without affecting meal size, whereas 15 mg/kg of C75 reduced both meal number and meal size. The two smaller doses of C75 failed to induce a CTA, but 15 mg/kg C75 did. The eating inhibitory effect of C75 was not diminished in either TVX or SDA rats. We conclude that intraperitoneal injections of low doses of C75 inhibit eating in a behaviorally specific manner and that this effect does not require abdominal vagal afferents.
Asunto(s)
4-Butirolactona/análogos & derivados , Conducta Alimentaria/efectos de los fármacos , Neuronas Aferentes/efectos de los fármacos , Nervio Vago/efectos de los fármacos , 4-Butirolactona/farmacología , Animales , Carnitina O-Palmitoiltransferasa/antagonistas & inhibidores , Carnitina O-Palmitoiltransferasa/metabolismo , Condicionamiento Psicológico/efectos de los fármacos , Condicionamiento Psicológico/fisiología , Relación Dosis-Respuesta a Droga , Ingestión de Alimentos/efectos de los fármacos , Ingestión de Alimentos/fisiología , Ácido Graso Sintasas/antagonistas & inhibidores , Ácido Graso Sintasas/metabolismo , Ácidos Grasos/metabolismo , Conducta Alimentaria/fisiología , Inyecciones Intraperitoneales , Masculino , Neuronas Aferentes/fisiología , Ratas , Ratas Sprague-Dawley , Vagotomía , Nervio Vago/citología , Nervio Vago/fisiologíaRESUMEN
PURPOSE: Fatty acid synthase (FAS) is overexpressed in lung cancer, and we have investigated the potential use of FAS inhibitors for chemoprevention of lung cancer. EXPERIMENTAL DESIGN: Expression of FAS was evaluated in preinvasive human lung lesions (bronchial squamous dysplasia and atypical adenomatous hyperplasia) and in murine models of lung tumorigenesis [4-(methylnitrosamino)-I-(3-pyridyl)-1-butanone-induced and urethane-induced lung tumors in A/J mice]. Then, the ability of pharmacologic inhibitors of FAS to prevent development of the murine tumors was investigated. Finally, the effect of the FAS inhibitor treatment of levels of phosphorylated Akt in the murine tumors was evaluated by immunohistochemistry. RESULTS: Immunohistochemical studies show that human bronchial dysplasia and atypical adenomatous hyperplasia express high levels of FAS compared with normal lung tissues, suggesting that FAS might be a target for intervention in lung carcinogenesis. FAS is also expressed at high levels in chemically induced murine lung tumors, and the numbers and sizes of those murine tumors are significantly reduced by treating carcinogen-exposed mice with pharmacologic inhibitors of FAS, C75 and C93. C93 treatment is associated with reduced levels of phosphorylated Akt in tumor tissues, suggesting that inhibition of this signal transduction pathway might be involved in the chemopreventative activity of this compound. CONCLUSIONS: We conclude that increased levels of FAS are common in human preinvasive neoplasia of the lung. Based on studies in mouse models, it seems that inhibiting FAS is an effective strategy in preventing and retarding growth of lung tumors that have high expression of this enzyme.
Asunto(s)
Anticarcinógenos/uso terapéutico , Inhibidores Enzimáticos/uso terapéutico , Ácido Graso Sintasas/antagonistas & inhibidores , Neoplasias Pulmonares/prevención & control , Animales , Femenino , Humanos , Neoplasias Pulmonares/inducido químicamente , Neoplasias Pulmonares/enzimología , Ratones , Nitrosaminas/toxicidad , Proteínas Proto-Oncogénicas c-akt/metabolismo , Uretano/toxicidadRESUMEN
Obesity, defined by a body mass index greater than 30kg/m(2), claims an increasing number of lives every year, underscoring a dire need for effective therapeutic interventions. The origins of the obesity epidemic are complex, but commonly cited factors include the large quantities of calorie-rich food that are readily accessible in modern society; eating habits adapted to fast-paced lifestyles; low levels of physical activity; and genetic programs that have evolved, especially in populations prone to famine, to favor the storage of excess calories (i.e., the thrifty-gene theory). It is estimated that more than thirty percent of adults, and about fifteen percent of juveniles, are obese. These high rates have led to dramatic increases in diseases such as type 2 diabetes, cardiovascular and respiratory diseases, depression, and some forms of cancer.
Asunto(s)
Fármacos Antiobesidad/farmacología , Fármacos Antiobesidad/uso terapéutico , Obesidad/tratamiento farmacológico , Obesidad/epidemiología , Moduladores de Receptores de Cannabinoides/metabolismo , Metabolismo Energético/efectos de los fármacos , Humanos , Hormonas Peptídicas/metabolismoRESUMEN
Inhibition of brain carnitine palmitoyl-transferase-1 (CPT-1) is reported to decrease food intake and body weight in rats. Yet, the fatty acid synthase (FAS) inhibitor and CPT-1 stimulator C75 produces hypophagia and weight loss when given to rodents intracerebroventricularly (icv). Thus roles and relative contributions of altered brain CPT-1 activity and fatty acid oxidation in these phenomena remain unclarified. We administered compounds that target FAS or CPT-1 to mice by single icv bolus and examined acute and prolonged effects on feeding and body weight. C75 decreased food intake rapidly and potently at all doses (1-56 nmol) and dose dependently inhibited intake on day 1. Dose-dependent weight loss on day 1 persisted through 4 days of postinjection monitoring. The FAS inhibitor cerulenin produced dose-dependent (560 nmol) hypophagia for 1 day, weight loss for 2 days, and weight regain to vehicle control by day 3. The CPT-1 inhibitor etomoxir (32, 320 nmol) did not alter overall day 1 feeding. However, etomoxir attenuated the hypophagia produced by C75, indicating that CPT-1 stimulation is important for C75's effect. A novel compound, C89b, was characterized in vitro as a selective stimulator of CPT-1 that does not affect fatty acid synthesis. C89b (100, 320 nmol) decreased feeding in mice for 3 days and produced persistent weight loss for 6 days without producing conditioned taste aversion. Similarly, intraperitoneal administration decreased feeding and body weight without producing conditioned taste aversion. These results suggest a role for brain CPT-1 in the regulation of energy balance and implicate CPT-1 stimulation as a pharmacological approach to weight loss.
Asunto(s)
Peso Corporal/fisiología , Carnitina O-Palmitoiltransferasa/metabolismo , Ingestión de Alimentos/fisiología , Hipotálamo/enzimología , 4-Butirolactona/análogos & derivados , 4-Butirolactona/farmacología , Animales , Peso Corporal/efectos de los fármacos , Línea Celular Tumoral , Relación Dosis-Respuesta a Droga , Ingestión de Alimentos/efectos de los fármacos , Metabolismo Energético/efectos de los fármacos , Metabolismo Energético/fisiología , Activación Enzimática/efectos de los fármacos , Activación Enzimática/fisiología , Inhibidores Enzimáticos/farmacología , Compuestos Epoxi/farmacología , Inhibidores de la Síntesis de Ácidos Grasos/metabolismo , Ácidos Grasos/metabolismo , Femenino , Hipotálamo/citología , Hipotálamo/efectos de los fármacos , Inyecciones Intraventriculares , Masculino , Ratones , Ratones Endogámicos BALB C , Ratones Endogámicos C57BL , Neuronas/citología , Neuronas/efectos de los fármacos , Neuronas/enzimología , Embarazo , RatasRESUMEN
PURPOSE: Fatty acid synthase (FAS) is overexpressed in many human cancers and is considered to be a promising target for therapy. However, in vitro use of previous generations of FAS inhibitors has been limited by severe, but reversible, anorexia in treated animals, which is thought to be related to a parallel stimulation of fatty acid oxidation by these agents. This study investigated pharmacologic inhibition of FAS using C93, a rationally designed molecule that inhibits FAS activity without affecting fatty acid oxidation in preclinical models of lung cancer. EXPERIMENTAL DESIGN: Activity of C93 on FAS and fatty acid oxidation was evaluated in cultured non-small cell lung cancer (NSCLC) cells. Antineoplastic activity of the compound, given orally or by i.p. injection, was evaluated in s.c. and orthotopic NSCLC xenografts. RESULTS: Our experiments confirm that C93 effectively inhibits FAS without stimulating fatty acid oxidation in lung cancer cells. More importantly, C93 significantly inhibits the growth of both s.c. and orthotopic xenograft tumors from human NSCLC cell lines without causing anorexia and weight loss in the treated animals. CONCLUSIONS: We conclude that inhibition of FAS can be achieved without parallel stimulation of fatty acid oxidation and that inhibition of tumor growth in vivo can be achieved without anorexia and weight loss. Thus, this therapeutic strategy holds promise for clinical treatment of cancers, including non-small cell lung cancer, the leading cause of cancer mortality in the United States and Europe.
Asunto(s)
Antineoplásicos/farmacología , Carcinoma de Pulmón de Células no Pequeñas/tratamiento farmacológico , Carcinoma de Pulmón de Células no Pequeñas/enzimología , Ácido Graso Sintasas/antagonistas & inhibidores , Inhibidores de la Síntesis de Ácidos Grasos/farmacología , Neoplasias Pulmonares/tratamiento farmacológico , Neoplasias Pulmonares/enzimología , Administración Oral , Animales , Anorexia/inducido químicamente , Antineoplásicos/toxicidad , Línea Celular Tumoral , Ácido Graso Sintasas/biosíntesis , Ácido Graso Sintasas/metabolismo , Inhibidores de la Síntesis de Ácidos Grasos/toxicidad , Ácidos Grasos/metabolismo , Humanos , Ratones , Ratones Desnudos , Oxidación-Reducción/efectos de los fármacos , Pérdida de Peso/efectos de los fármacos , Ensayos Antitumor por Modelo de XenoinjertoRESUMEN
PURPOSE: Fatty acid synthase (FAS) is an emerging target for anticancer therapy with a variety of new FAS inhibitors being explored in preclinical models. The aim of this study was to use positron emission tomography with [(18)F]fluorodeoxyglucose (FDG-PET) to monitor the effects of the FAS inhibitor C75 on tumor glucose metabolism in a rodent model of human A549 lung cancer. MATERIALS AND METHODS: After a baseline FDG-PET scan, C75 was administered and post-treatment scans were performed serially. FAS activity was measured in treated animals ex vivo by [(14)C]acetate incorporation in animals euthanized in parallel to those imaged. RESULTS: Longitudinally measured metabolic volumes of interest and tumor/background ratios demonstrated a transient, reversible decrease in glucose metabolism and tumor metabolic volume after treatment, with the peak effect seen at 4 h. FDG-PET measurements correlated with changes in tumor FAS activity measured ex vivo. CONCLUSIONS: Because C75 causes an effect that is shorter in duration than expected, modification of the current weekly dosing regimen should be considered. These results demonstrate the utility of small animal FDG-PET in assessing the pharmacodynamics of new anticancer agents in preclinical models.
Asunto(s)
4-Butirolactona/análogos & derivados , Modelos Animales de Enfermedad , Inhibidores Enzimáticos/farmacología , Ácido Graso Sintasas/antagonistas & inhibidores , Fluorodesoxiglucosa F18 , Neoplasias Pulmonares/diagnóstico por imagen , 4-Butirolactona/farmacología , Animales , Tomografía de Emisión de Positrones , RatasRESUMEN
Fatty acid synthase (FAS), the enzyme responsible for the de novo synthesis of fatty acids, is highly expressed in ovarian cancers and most common human carcinomas. Inhibition of FAS and activation of AMP-activated protein kinase (AMPK) have been shown to be cytotoxic to human cancer cells in vitro and in vivo. In this report, we explore the cytotoxic mechanism of action of FAS inhibition and show that C93, a synthetic FAS inhibitor, increases the AMP/ATP ratio, activating AMPK in SKOV3 human ovarian cancer cells, which leads to cytotoxicity. As a physiologic consequence of AMPK activation, acetyl-CoA carboxylase (ACC), the rate-limiting enzyme of fatty acid synthesis, was phosphorylated and inhibited whereas glucose oxidation was increased. Despite these attempts to conserve energy, the AMP/ATP ratio increased with worsening cellular redox status. Pretreatment of SKOV3 cells with compound C, an AMPK inhibitor, substantially rescued the cells from C93 cytotoxicity, indicating its dependence on AMPK activation. 5-(Tetradecyloxy)-2-furoic acid, an ACC inhibitor, did not activate AMPK despite inhibiting fatty acid synthesis pathway activity and was not significantly cytotoxic to SKOV3 cells. This indicates that substrate accumulation from FAS inhibition triggering AMPK activation, not end-product depletion of fatty acids, is likely responsible for AMPK activation. C93 also exhibited significant antitumor activity and apoptosis against SKOV3 xenografts in athymic mice without significant weight loss or cytotoxicity to proliferating cellular compartments such as bone marrow, gastrointestinal tract, or skin. Thus, pharmacologic FAS inhibition selectively activates AMPK in ovarian cancer cells, inducing cytotoxicity while sparing most normal human tissues from the pleiotropic effects of AMPK activation.
Asunto(s)
Inhibidores Enzimáticos/farmacología , Ácido Graso Sintasas/antagonistas & inhibidores , Complejos Multienzimáticos/metabolismo , Neoplasias Ováricas/tratamiento farmacológico , Neoplasias Ováricas/enzimología , Proteínas Serina-Treonina Quinasas/metabolismo , Proteínas Quinasas Activadas por AMP , Secuencia de Aminoácidos , Animales , Línea Celular Tumoral , Activación Enzimática , Ácidos Grasos/metabolismo , Femenino , Furanos/farmacología , Glucosa/metabolismo , Humanos , Ratones , Ratones Endogámicos BALB C , Datos de Secuencia Molecular , NAD/metabolismo , Neoplasias Ováricas/metabolismo , Oxidación-Reducción , Ensayos Antitumor por Modelo de XenoinjertoRESUMEN
The rising incidence of obesity, as a disorder of energy metabolism, has provoked a search for pharmacological agents that either increase energy expenditure or reduce food intake. The fatty acid oxidation pathway, and its rate-limiting enzyme carnitine palmitoyltransferase (CPT)-1 are potential targets for the treatment of obesity. The modulation of CPT-1 may simultaneously affect energy metabolism and food intake to aid in the management of obesity. Both the inhibition and enhancement of CPT-1 activity are currently under investigation as strategies for the treatment of obesity. In this review, key data on both sides of the 'CPT-1 activity balance' as they relate to obesity therapy are discussed.
Asunto(s)
Carnitina O-Palmitoiltransferasa/antagonistas & inhibidores , Carnitina O-Palmitoiltransferasa/metabolismo , Obesidad/tratamiento farmacológico , Animales , Activación Enzimática/efectos de los fármacos , Ácidos Grasos/metabolismo , Humanos , Lactonas/farmacología , Lactonas/uso terapéutico , Modelos Biológicos , Estructura Molecular , Obesidad/enzimología , Obesidad/patologíaRESUMEN
Fatty acid synthase (FAS), the sole mammalian enzyme capable of de novo fatty acid synthesis, is highly expressed in most human carcinomas. FAS is associated with poor prognosis in breast and prostate cancer, is elaborated into the blood of cancer patients, and its inhibition is selectively cytotoxic to human cancer cells. Thus, FAS and fatty acid metabolism in cancer has become a focus for the potential diagnosis and treatment of cancer.
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Ácido Graso Sintasas/metabolismo , Neoplasias/enzimología , Animales , Neoplasias de la Mama/enzimología , Ácido Graso Sintasas/antagonistas & inhibidores , Femenino , Humanos , Masculino , Neoplasias de la Próstata/enzimologíaRESUMEN
3-Carboxy-4-alkyl-2-methylenebutyrolactone (C75), an inhibitor of fatty acid synthase and stimulator of carnitine palmitoyltransferase-1, reduces food intake and body weight in rodents when given systemically or centrally. Intracellular molecular mechanisms involving changes in cellular energy status are proposed to initiate the feeding and body weight reductions. However, effectors that lie downstream of these initial steps are not yet fully identified. Present experiments characterize the time courses of hypophagia and weight loss after single injections of C75 into the lateral cerebroventicle in rats and go on to identify specific meal pattern changes and coinciding alterations in gene expression for feeding-related hypothalamic neuropeptides. C75 reduced chow intake and body weight dose dependently. Although the principal effects occurred on the first day, weight losses relative to vehicle control were maintained over multiple days. C75 did not affect generalized locomotor activity. C75 began to reduce feeding after a 6-h delay. The hypophagia was due primarily to decreased meal number during 6-12 h without a significant effect on meal size, suggesting that central C75 reduced the drive to initiate meals. C75 prevented the anticipated hypophagia-induced increases in mRNA for AgRP in the arcuate nucleus at 22 h and at 6 h when C75 begins to suppress feeding. Overall, the data suggest that gene expression changes leading to altered melanocortin signaling are important for the hypophagic response to intracerebroventricular C75.
Asunto(s)
4-Butirolactona/análogos & derivados , Conducta Alimentaria/efectos de los fármacos , Hormonas Peptídicas/metabolismo , 4-Butirolactona/farmacología , Proteína Relacionada con Agouti , Animales , Peso Corporal/efectos de los fármacos , Regulación de la Expresión Génica , Péptidos y Proteínas de Señalización Intercelular , Masculino , Actividad Motora/efectos de los fármacos , Hormonas Peptídicas/efectos de los fármacos , Hormonas Peptídicas/genética , ARN Mensajero/metabolismo , Ratas , Ratas Sprague-DawleyRESUMEN
Obesity and its attendant disorders, such as Type II diabetes, have reached epidemic proportions in the USA, and their prevalence is increasing globally. C75 is a small-molecule inhibitor of fatty acid synthase (FAS) and a stimulator of carnitine palmitoyl 1 activity, which causes profound weight loss in mice. Although C75 is not a compound that is destined for human drug development, it has provided two potential pathways to target in obesity therapy: fatty acid synthesis and fatty acid oxidation. In this article, we discuss the latest data challenging the relationship between fatty acid synthase inhibition and C75-induced anorexia.
Asunto(s)
4-Butirolactona/análogos & derivados , Ácido Graso Sintasas/antagonistas & inhibidores , Obesidad/metabolismo , 4-Butirolactona/administración & dosificación , 4-Butirolactona/farmacocinética , 4-Butirolactona/farmacología , Proteínas Quinasas Activadas por AMP , Animales , Anorexia/etiología , Carnitina O-Palmitoiltransferasa/metabolismo , Modelos Animales de Enfermedad , Ingestión de Alimentos/efectos de los fármacos , Metabolismo Energético/efectos de los fármacos , Inhibidores Enzimáticos/farmacología , Ácidos Grasos/metabolismo , Conducta Alimentaria/efectos de los fármacos , Hipotálamo/efectos de los fármacos , Hipotálamo/enzimología , Ratones , Complejos Multienzimáticos/antagonistas & inhibidores , Proteínas Serina-Treonina Quinasas/antagonistas & inhibidores , Ratas , Rombencéfalo/efectos de los fármacos , Rombencéfalo/enzimologíaRESUMEN
Activation of AKT and overexpression of fatty acid synthase (FAS) are frequently observed in human ovarian cancer. To explore a possible connection between AKT and FAS, immunohistochemical analyses were conducted on an ovarian cancer tissue microarray, which revealed a significant correlation between phosphorylated AKT (phospho-AKT) and expression of FAS. To investigate the relationship between phospho-AKT and FAS in vitro, a variety of experiments employing a specific phosphatidylinositol 3-OH kinase (PI3K) inhibitor (LY294002), inducible PTEN expression in PTEN-null cells, or AKT1 siRNA demonstrated that phosphatidylinositol-3 kinase (PI3K)/AKT signaling modulates FAS expression. In contrast, inhibition of FAS activity by the drug C75 resulted in downregulation of phospho-AKT and increased cell death. To explore the functional relationship between phospho-AKT and FAS, we used SKOV3, C200, and OVCAR10 ovarian carcinoma cells, which have constitutively active AKT, and OVCAR5 cells, which have very low basal phospho-AKT levels. Treatment with LY294002 abolished AKT activity and potentiated apoptosis induced by FAS inhibitors cerulenin or C75 only in cells with constitutively active AKT, suggesting that constitutive activation of AKT protects against FAS inhibitor-induced cell death. Furthermore, inhibition of FAS activity by cerulenin or C75 resulted in downregulation of phospho-AKT, which preceded the induction of apoptosis. To investigate the relationship between phospho-AKT and FAS in vivo, severe combined immunodeficient mice injected intraperitoneally with SKOV3 cells were treated with C75. Growth of SKOV3 xenografts was markedly inhibited by C75. Analysis of the levels of phospho-AKT and FAS in C75-treated tumors revealed concordant downregulation of phospho-AKT and FAS. Collectively, our findings are consistent with a working model in which AKT activation regulates FAS expression, at least in part, whereas FAS activity modulates AKT activation.
Asunto(s)
4-Butirolactona/análogos & derivados , Activación Enzimática/fisiología , Ácido Graso Sintasas/biosíntesis , Retroalimentación Fisiológica/fisiología , Neoplasias Ováricas/enzimología , Proteínas Serina-Treonina Quinasas/metabolismo , Proteínas Proto-Oncogénicas/metabolismo , 4-Butirolactona/farmacología , Animales , Apoptosis/efectos de los fármacos , Apoptosis/fisiología , Western Blotting , Línea Celular Tumoral , Activación Enzimática/efectos de los fármacos , Inhibidores Enzimáticos/farmacología , Femenino , Humanos , Inmunohistoquímica , Ratones , Fosfohidrolasa PTEN , Fosfatidilinositol 3-Quinasas/efectos de los fármacos , Fosfatidilinositol 3-Quinasas/metabolismo , Monoéster Fosfórico Hidrolasas/genética , Proteínas Serina-Treonina Quinasas/efectos de los fármacos , Proteínas Proto-Oncogénicas/efectos de los fármacos , Proteínas Proto-Oncogénicas c-akt , ARN Interferente Pequeño , Proteínas Supresoras de Tumor/genéticaRESUMEN
Fatty acid synthase (FAS) catalyzes the synthesis of palmitate from the sequential condensation of an acetyl primer with two carbon units added from malonyl-CoA. Inhibition of the beta-ketoacyl synthase domain of mammalian FAS leads to selective cytotoxicity to various cancer cell lines in vitro and in vivo. Also, inhibitors of FAS can cause reduced food intake and body weight in mice. Naturally occurring thiolactomycin (TLM) was used as a template to develop a new class of type I FAS inhibitors. Using a flexible synthesis, families of TLM structural analogues were obtained that possess selective FAS activity and display anticancer and weight loss effects. Compounds 13a and 13d inhibit pure FAS (ZR-75-1 breast cancer, IC(50) = Asunto(s)
Fármacos Antiobesidad/síntesis química
, Antineoplásicos/síntesis química
, Ácido Graso Sintasas/antagonistas & inhibidores
, Tiofenos/síntesis química
, Animales
, Fármacos Antiobesidad/química
, Fármacos Antiobesidad/farmacología
, Antineoplásicos/química
, Antineoplásicos/farmacología
, Peso Corporal/efectos de los fármacos
, Línea Celular Tumoral
, Ensayos de Selección de Medicamentos Antitumorales
, Ácido Graso Sintasas/química
, Humanos
, Ratones
, Ratones Endogámicos BALB C
, Modelos Moleculares
, Estereoisomerismo
, Relación Estructura-Actividad
, Tiofenos/química
, Tiofenos/farmacología
RESUMEN
C75, a synthetic inhibitor of fatty acid synthase (FAS), causes anorexia and profound weight loss in lean and genetically obese mice. C75 also acts as a stimulator of carnitine palmitoyltransferase-1 to induce fatty acid oxidation. To approximate human obesity, we used a 2-wk C75 treatment model for diet-induced obese (DIO) mice to investigate the central and peripheral effects of C75 on gene expression. C75 treatment decreased food intake, increased energy expenditure, and reduced body weight more effectively in DIO than in lean mice. Analysis of the gene expression changes in hypothalamus demonstrated that the reduced food intake in C75-treated DIO mice might be mediated by inhibition of orexigenic neuropeptide expression and induction of anorexigenic neuropeptide expression. Gene expression changes in peripheral tissues indicated that C75 increased energy expenditure by the induction of genes involved in fatty acid oxidation. C75 also inhibited the expression of genes in peripheral tissues responsible for fatty acid synthesis and accumulation. The patterns of the changes in central and peripheral gene expression that occur with C75 treatment provide mechanisms to explain the reduced food intake and increased energy expenditure observed with C75.
Asunto(s)
4-Butirolactona/análogos & derivados , 4-Butirolactona/farmacología , Ingestión de Alimentos/efectos de los fármacos , Metabolismo Energético/efectos de los fármacos , Expresión Génica/efectos de los fármacos , Obesidad/genética , Animales , Peso Corporal/efectos de los fármacos , Dieta , Ingestión de Alimentos/genética , Metabolismo Energético/genética , Ácido Graso Sintasas/antagonistas & inhibidores , Ácidos Grasos/metabolismo , Hipotálamo/metabolismo , Masculino , Ratones , Ratones Endogámicos C57BL , Neuropéptidos/genética , Neuropéptidos/metabolismo , Obesidad/etiología , Obesidad/patología , Obesidad/fisiopatología , Oxidación-Reducción/efectos de los fármacos , Delgadez/genética , Delgadez/metabolismo , Delgadez/patologíaRESUMEN
High levels of fatty acid synthase (FAS) have been found in cancer precursor lesions of the colon, stomach, esophagus, oral cavity, prostate, and breast. Inhibition of FAS with C75 has led to a significant antitumor effect in both human breast and prostate cancer xenografts. Recently, HER2/neu, which has also been identified in preneoplastic breast lesions, has been shown to regulate FAS expression through the PI3K/Akt signal transduction pathway rendering them susceptible to FAS inhibition. Utilizing the neu-N transgenic mouse model of mammary cancer, weekly treatment of the neu-N mice with C75 (30 mg/kg) for 10 weeks significantly delayed tumor progression. Only 20% of the C75-treated transgenic mice developed mammary carcinoma by 220 days, compared to 50% in the vehicle control animals. Two C75-treated animals never developed mammary cancer. Analysis of mammary tissue following 10 weeks of C75 treatment revealed a significant delay in mammary maturation as manifested by a reduction of the number and caliber of mammary ducts and budding epithelial structures. Apoptotic changes were increased, DNA synthesis was decreased, and the expressions of FAS, neu, Akt, phospho-Akt, and p21(waf1) were all decreased when compared to vehicle controls and FVB/N mice. Importantly, these effects were restricted to the breast epithelial cells that overexpressed neu, not involving other normal duct structures in the skin, liver, or kidney. C247, an FAS inhibitor chemically distinct from C75, significantly delayed mammary maturation similar to C75. Thus, pharmacological inhibition of FAS affects the expression of key oncogenes involved in both cancer development and maintenance of the malignant phenotype. Moreover, these data identify FAS as a potential novel drug target for breast cancer chemoprevention.
Asunto(s)
4-Butirolactona/análogos & derivados , Ácido Graso Sintasas/antagonistas & inhibidores , Neoplasias Mamarias Animales/prevención & control , Proteínas del Tejido Nervioso/genética , Proteínas Nucleares/genética , 4-Butirolactona/farmacología , Animales , Proteínas de Unión al ADN , Femenino , Glándulas Mamarias Animales/efectos de los fármacos , Glándulas Mamarias Animales/crecimiento & desarrollo , Ratones , Ratones Transgénicos , Proteínas del Tejido Nervioso/metabolismo , Proteínas Nucleares/metabolismo , Receptores del Factor de Necrosis Tumoral/metabolismo , Células Tumorales Cultivadas , Receptor fasRESUMEN
Overexpression of fatty acid synthase (FAS EC 2.3.1.85) is associated with certain cancers and therefore is a putative tumor marker. The presence of FAS in patients with breast, prostate, colon, ovarian, and other cancers has been reported. The mechanism of FAS overexpression in malignancies remains unknown. Here, we show that FAS is released into the extracellular space in cancer cells. The extracellular FAS are present in various immunoreactive forms, and show different expression patterns in various cancer cells. In serum of breast cancer patients, the FAS is a small molecule similar to the form in breast cancer cell lysate but not conditioned medium of cultured cells. The extracellular expression of FAS in breast cancer cells is time dependent and may be hormone independent. These results indicate that the FAS are an ordered cellular response of a living cell and actively exclude excess intracellular FAS molecules from the cell. This phenomenon is up-regulated in breast and may be in other cancer cells as well. Significant elevation of FAS was detected in serum of breast cancer patients compared to healthy subjects. In comparison with CA27.29, no correlation between these two tumor markers was found. Thus, the extracellular FAS may serve as a potential diagnostic and prognostic marker.