RESUMO
Fatty acid binding protein 4 (FABP4) is a fatty acid chaperone, which is induced during adipocyte differentiation. Previously we have shown that FABP4 in endothelial cells is induced by the NOTCH1 signalling pathway, the latter of which is involved in mechanisms of resistance to antiangiogenic tumour therapy. Here, we investigated the role of FABP4 in endothelial fatty acid metabolism and tumour angiogenesis. We analysed the effect of transient FABP4 knockdown in human umbilical vein endothelial cells on fatty acid metabolism, viability and angiogenesis. Through therapeutic delivery of siRNA targeting mouse FABP4, we investigated the effect of endothelial FABP4 knockdown on tumour growth and blood vessel formation. In vitro, siRNA-mediated FABP4 knockdown in endothelial cells led to a marked increase of endothelial fatty acid oxidation, an increase of reactive oxygen species and decreased angiogenesis. In vivo, we found that increased NOTCH1 signalling in tumour xenografts led to increased expression of endothelial FABP4 that decreased when NOTCH1 and VEGFA inhibitors were used in combination. Angiogenesis, growth and metastasis in ovarian tumour xenografts were markedly inhibited by therapeutic siRNA delivery targeting mouse endothelial FABP4. Therapeutic targeting of endothelial FABP4 by siRNA in vivo has antiangiogenic and antitumour effects with minimal toxicity and should be investigated further.
Assuntos
Inibidores da Angiogênese/metabolismo , Cistadenocarcinoma Seroso/prevenção & controle , Proteínas de Ligação a Ácido Graxo/antagonistas & inibidores , Neovascularização Patológica/prevenção & controle , Neoplasias Ovarianas/prevenção & controle , Animais , Apoptose , Biomarcadores Tumorais/metabolismo , Movimento Celular , Proliferação de Células , Cistadenocarcinoma Seroso/irrigação sanguínea , Cistadenocarcinoma Seroso/metabolismo , Cistadenocarcinoma Seroso/patologia , Proteínas de Ligação a Ácido Graxo/genética , Proteínas de Ligação a Ácido Graxo/metabolismo , Feminino , Seguimentos , Células Endoteliais da Veia Umbilical Humana/metabolismo , Células Endoteliais da Veia Umbilical Humana/patologia , Humanos , Camundongos , Camundongos Nus , Gradação de Tumores , Invasividade Neoplásica , Neovascularização Patológica/metabolismo , Neovascularização Patológica/patologia , Neoplasias Ovarianas/irrigação sanguínea , Neoplasias Ovarianas/metabolismo , Neoplasias Ovarianas/patologia , Prognóstico , Estudos Prospectivos , Receptor Notch1/metabolismo , Transdução de Sinais , Taxa de Sobrevida , Células Tumorais Cultivadas , Fator A de Crescimento do Endotélio Vascular/metabolismo , Ensaios Antitumorais Modelo de XenoenxertoRESUMO
MicroRNAs (miRNAs) are small RNA molecules that affect cellular processes by controlling gene expression. Recent studies have shown that hypoxia downregulates Drosha and Dicer, key enzymes in miRNA biogenesis, causing a decreased pool of miRNAs in cancer and resulting in increased tumor growth and metastasis. Here we demonstrate a previously unrecognized mechanism by which hypoxia downregulates Dicer. We found that miR-630, which is upregulated under hypoxic conditions, targets and downregulates Dicer expression. In an orthotopic mouse model of ovarian cancer, delivery of miR-630 using 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC) nanoliposomes resulted in increased tumor growth and metastasis, and decreased Dicer expression. Treatment with the combination of anti-miR-630 and anti-vascular endothelial growth factor antibody in mice resulted in rescue of Dicer expression and significantly decreased tumor growth and metastasis. These results indicate that targeting miR-630 is a promising approach to overcome Dicer deregulation in cancer. As demonstrated in the study, use of DOPC nanoliposomes for anti-miR delivery serves as a better alternative approach to cell line-based overexpression of sense or antisense miRNAs, while avoiding potential in vitro selection effects. Findings from this study provide a new understanding of miRNA biogenesis downregulation observed under hypoxia and suggest therapeutic avenues to target this dysregulation in cancer.
Assuntos
Hipóxia Celular , RNA Helicases DEAD-box/genética , Regulação Neoplásica da Expressão Gênica , MicroRNAs/fisiologia , Neoplasias/etiologia , Ribonuclease III/genética , Animais , Linhagem Celular Tumoral , Progressão da Doença , Feminino , Humanos , Lipossomos , Camundongos , MicroRNAs/antagonistas & inibidores , Neoplasias/terapia , Neoplasias Ovarianas/metabolismo , Fosfatidilcolinas/administração & dosagem , Fator A de Crescimento do Endotélio Vascular/antagonistas & inibidoresRESUMO
Adrenergic stimulation adversely affects tumor growth and metastasis, but the underlying mechanisms are not well understood. Here, we uncovered a novel mechanism by which catecholamines induce inflammation by increasing prostaglandin E2 (PGE2) levels in ovarian cancer cells. Metabolic changes in tumors isolated from patients with depression and mice subjected to restraint stress showed elevated PGE2 levels. Increased metabolites, PTGS2 and PTGES protein levels were found in Skov3-ip1 and HeyA8 cells treated with norepinephrine (NE), and these changes were shown to be mediated by ADRB2 receptor signaling. Silencing PTGS2 resulted in significantly decreased migration and invasion in ovarian cancer cells in the presence of NE and decreased tumor burden and metastasis in restraint stress orthotopic models. In human ovarian cancer samples, concurrent increased ADRB2, PTGS2 and PTGES expression was associated with reduced overall and progression-free patient survival. In conclusion, increased adrenergic stimulation results in increased PGE2 synthesis via ADRB2-Nf-kB-PTGS2 axis, which drives tumor growth and metastasis.
