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1.
J Clin Invest ; 122(1): 178-91, 2012 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-22182838

RESUMEN

Epoxyeicosatrienoic acids (EETs) are small molecules produced by cytochrome P450 epoxygenases. They are lipid mediators that act as autocrine or paracrine factors to regulate inflammation and vascular tone. As a result, drugs that raise EET levels are in clinical trials for the treatment of hypertension and many other diseases. However, despite their pleiotropic effects on cells, little is known about the role of these epoxyeicosanoids in cancer. Here, using genetic and pharmacological manipulation of endogenous EET levels, we demonstrate that EETs are critical for primary tumor growth and metastasis in a variety of mouse models of cancer. Remarkably, we found that EETs stimulated extensive multiorgan metastasis and escape from tumor dormancy in several tumor models. This systemic metastasis was not caused by excessive primary tumor growth but depended on endothelium-derived EETs at the site of metastasis. Administration of synthetic EETs recapitulated these results, while EET antagonists suppressed tumor growth and metastasis, demonstrating in vivo that pharmacological modulation of EETs can affect cancer growth. Furthermore, inhibitors of soluble epoxide hydrolase (sEH), the enzyme that metabolizes EETs, elevated endogenous EET levels and promoted primary tumor growth and metastasis. Thus, our data indicate a central role for EETs in tumorigenesis, offering a mechanistic link between lipid signaling and cancer and emphasizing the critical importance of considering possible effects of EET-modulating drugs on cancer.


Asunto(s)
Eicosanoides/metabolismo , Metástasis de la Neoplasia/fisiopatología , Neoplasias Experimentales/metabolismo , Animales , Hidrocarburo de Aril Hidroxilasas/genética , Hidrocarburo de Aril Hidroxilasas/metabolismo , Citocromo P-450 CYP2C8 , Citocromo P-450 CYP2J2 , Inhibidores Enzimáticos del Citocromo P-450 , Sistema Enzimático del Citocromo P-450/genética , Sistema Enzimático del Citocromo P-450/metabolismo , Endotelio Vascular/metabolismo , Compuestos Epoxi/metabolismo , Humanos , Masculino , Ratones , Ratones Endogámicos C57BL , Ratones Noqueados , Ratones Transgénicos , Metástasis de la Neoplasia/patología , Neoplasias Experimentales/irrigación sanguínea , Neoplasias Experimentales/patología , Neovascularización Patológica , Proteínas Recombinantes/genética , Proteínas Recombinantes/metabolismo , Factor A de Crecimiento Endotelial Vascular/metabolismo
2.
Exp Ther Med ; 1(5): 739-746, 2010 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-22993597

RESUMEN

The chemotherapeutic agent etoposide is a topoisomerase II inhibitor widely used for cancer therapy. Low-dose oral etoposide, administered at close regular intervals, has potent anti-tumor activity in patients who are refractory to intravenous etoposide; however, the mechanism remains unclear. Since endothelial cells may be more sensitive than tumor cells to chemotherapy agents, we determined the effects of etoposide alone and in combination with oral cyclooxygenase-2 inhibitors and peroxisome-proliferator activated receptor γ ligands on angiogenesis and tumor growth in xenograft tumor models. Optimal anti-angiogenic (metronomic) and anti-tumor doses of etoposide on angiogenesis, primary tumor growth and metastasis were established alone and in combination therapy. Etoposide inhibited endothelial and tumor cell proliferation, decreased vascular endothelial growth factor (VEGF) production by tumor cells and suppressed endothelial tube formation at non-cytotoxic concentrations. In our in vivo studies, oral etoposide inhibited fibroblast growth factor 2 and VEGF-induced corneal neovascularization, VEGF-induced vascular permeability and increased levels of the endogenous angiogenesis inhibitor endostatin in mice. In addition, etoposide inhibited Lewis lung carcinoma (LLC) and human glioblastoma (U87) primary tumor growth as well as spontaneous lung metastasis in a LLC resection model. Furthermore, etoposide had synergistic anti-tumor activity in combination with celecoxib and rosiglitazone, which are also oral anti-angiogenic and anti-tumor agents. Etoposide inhibits angiogenesis in vitro and in vivo by indirect and direct mechanisms of action. Combining etoposide with celecoxib and rosiglitazone increases its efficacy and merits further investigation in future clinical trials to determine the potential usefulness of etoposide in combinatory anti-angiogenic chemotherapy.

3.
Proc Natl Acad Sci U S A ; 105(3): 985-90, 2008 Jan 22.
Artículo en Inglés | MEDLINE | ID: mdl-18199835

RESUMEN

Angiogenesis and inflammation are central processes through which the tumor microenvironment influences tumor growth. We have demonstrated recently that peroxisome proliferator-activated receptor (PPAR)alpha deficiency in the host leads to overt inflammation that suppresses angiogenesis via excess production of thrombospondin (TSP)-1 and prevents tumor growth. Hence, we speculated that pharmacologic activation of PPARalpha would promote tumor growth. Surprisingly, the PPARalpha agonist fenofibrate potently suppressed primary tumor growth in mice. This effect was not mediated by cancer-cell-autonomous antiproliferative mechanisms but by the inhibition of angiogenesis and inflammation in the host tissue. Although PPARalpha-deficient tumors were still susceptible to fenofibrate, absence of PPARalpha in the host animal abrogated the potent antitumor effect of fenofibrate. In addition, fenofibrate suppressed endothelial cell proliferation and VEGF production, increased TSP-1 and endostatin, and inhibited corneal neovascularization. Thus, both genetic abrogation of PPARalpha as well as its activation by ligands cause tumor suppression via overlapping antiangiogenic pathways. These findings reveal the potential utility of the well tolerated PPARalpha agonists beyond their use as lipid-lowering drugs in anticancer therapy. Our results provide a mechanistic rationale for evaluating the clinical benefits of PPARalpha agonists in cancer treatment, alone and in combination with other therapies.


Asunto(s)
Fenofibrato/farmacología , Neoplasias/irrigación sanguínea , Neoplasias/metabolismo , PPAR alfa/agonistas , Animales , Línea Celular Tumoral , Córnea/irrigación sanguínea , Córnea/efectos de los fármacos , Córnea/metabolismo , Células Endoteliales/metabolismo , Endotelio/metabolismo , Fenofibrato/uso terapéutico , Factor 2 de Crecimiento de Fibroblastos/farmacología , Humanos , Ligandos , Ratones , Ratones Endogámicos C57BL , Ratones Noqueados , Neoplasias/tratamiento farmacológico , Neoplasias/patología , PPAR alfa/deficiencia , PPAR alfa/genética , PPAR alfa/metabolismo
4.
Psychon Bull Rev ; 12(6): 1005-10, 2005 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-16615320

RESUMEN

Directed forgetting is shown as impaired performance on a memory test following an instruction that the presented items will not be tested. Experiments utilizing the delayed matching-to-sample (DMTS) task have demonstrated that this ability to actively control memory is present in animals; however, no study has yet confirmed that cues to forget established in one DMTS discrimination will successfully transfer to other discriminations. Lacking such evidence, it is not clear whether forgetting cues act as "higher level" task instructions or are represented more simply, perhaps as part of a sample-specific sequence of events. The present study revealed good transfer of the forget cue function in pigeons after prior training with the forget cues in a separate discrimination. This finding is discussed in relation to analogous experiments on occasion setting, in which training within more than one discriminative context has been shown to be critical to the transfer of a conditional relation.


Asunto(s)
Señales (Psicología) , Discriminación en Psicología , Memoria , Transferencia de Experiencia en Psicología , Animales , Conducta Animal , Columbidae
5.
J Reprod Med ; 43(10): 898-902, 1998 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-9800674

RESUMEN

OBJECTIVE: To correlate fetal morphometrics with studies of fetal lung maturity. STUDY DESIGN: One hundred six patients undergoing amniocentesis for fetal lung maturity studies were examined prospectively. Eighty-four patients were normal (79%), and 22 were diabetic (21%). Fetal morphometrics were obtained prior to amniocentesis. The fetal colon and placenta were graded. Discriminant analysis was used to identify variables that were predictive of a mature lecithin/sphingomyelin ratio and the presence of phosphatidylglycerol (PG). All patients delivered within 48 hours of amniocentesis. RESULTS: In the normal group, 28 (33%) fetuses had a grade 3 colon, which was 68% sensitive and 98% specific for a mature amniocentesis. A grade 3 colon was the single best predictor of a mature amniocentesis (P < .001). Twenty-five (29%) fetuses had a grade 3 placenta, which was 64% sensitive and 96% specific for a mature amniocentesis (P < .005). Diabetes did not influence colonic grading since a grade 3 colon was present in seven (32%) patients (47% sensitivity and 100% specificity for PG) (P < .02). Interexaminer and intraexaminer variability for the study was excellent, kappa = 1.0 (P < .001). CONCLUSION: Colonic and placental stage 3 grading are reliable and reproducible ultrasonographic scales that can help predict the findings of fetal lung maturity studies.


Asunto(s)
Pulmón/embriología , Ultrasonografía Prenatal/métodos , Adulto , Antropometría , Colon/diagnóstico por imagen , Colon/embriología , Diabetes Gestacional/complicaciones , Femenino , Madurez de los Órganos Fetales , Humanos , Pulmón/diagnóstico por imagen , Placenta/diagnóstico por imagen , Placenta/fisiología , Valor Predictivo de las Pruebas , Embarazo
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