RESUMEN
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.
Asunto(s)
Hipoxia de la Célula , ARN Helicasas DEAD-box/genética , Regulación Neoplásica de la Expresión Génica , MicroARNs/fisiología , Neoplasias/etiología , Ribonucleasa III/genética , Animales , Línea Celular Tumoral , Progresión de la Enfermedad , Femenino , Humanos , Liposomas , Ratones , MicroARNs/antagonistas & inhibidores , Neoplasias/terapia , Neoplasias Ováricas/metabolismo , Fosfatidilcolinas/administración & dosificación , Factor A de Crecimiento Endotelial Vascular/antagonistas & inhibidoresRESUMEN
In the absence of extracellular stimulation the adaptor protein growth factor receptor-bound protein (Grb2) and the phospholipase Plcγ1 compete for the same binding site on fibroblast growth factor receptor 2 (FGFR2). Reducing cellular Grb2 results in upregulation of Plcγ1 and depletion of the phospholipid PI(4,5)P2. The functional consequences of this event on signaling pathways are unknown. We show that the decrease in PI(4,5)P2 level under non-stimulated conditions inhibits PTEN activity leading to the aberrant activation of the oncoprotein Akt. This results in excessive cell proliferation and tumor progression in a xenograft mouse model. As well as defining a novel mechanism of Akt phosphorylation with important therapeutic consequences, we also demonstrate that differential expression levels of FGFR2, Plcγ1 and Grb2 correlate with patient survival. Oncogenesis through fluctuation in the expression levels of these proteins negates extracellular stimulation or mutation and defines them as novel prognostic markers in ovarian cancer.
Asunto(s)
Proteína Adaptadora GRB2/genética , Proteína Oncogénica v-akt/genética , Neoplasias Ováricas/genética , Fosfohidrolasa PTEN/genética , Fosfolipasa C gamma/genética , Receptor Tipo 2 de Factor de Crecimiento de Fibroblastos/genética , Animales , Carcinogénesis/genética , Proliferación Celular/genética , Femenino , Proteína Adaptadora GRB2/antagonistas & inhibidores , Regulación Neoplásica de la Expresión Génica , Humanos , Ratones , Neoplasias Ováricas/patología , Fosfohidrolasa PTEN/antagonistas & inhibidores , Fosfatidilinositol 3-Quinasas/genética , Fosfatidilinositoles/metabolismo , Fosfolipasa C gamma/biosíntesis , Pronóstico , Receptor Tipo 2 de Factor de Crecimiento de Fibroblastos/biosíntesis , Transducción de SeñalRESUMEN
BACKGROUND: Simulation-based training assumes that skills are directly transferable to the patient-based setting, but few studies have correlated simulated performance with surgical performance. METHODS: A systematic search strategy was undertaken to find studies published since the last systematic review, published in 2007. Inclusion of articles was determined using a predetermined protocol, independent assessment by two reviewers and a final consensus decision. Studies that reported on the use of surgical simulation-based training and assessed the transferability of the acquired skills to a patient-based setting were included. RESULTS: Twenty-seven randomized clinical trials and seven non-randomized comparative studies were included. Fourteen studies investigated laparoscopic procedures, 13 endoscopic procedures and seven other procedures. These studies provided strong evidence that participants who reached proficiency in simulation-based training performed better in the patient-based setting than their counterparts who did not have simulation-based training. Simulation-based training was equally as effective as patient-based training for colonoscopy, laparoscopic camera navigation and endoscopic sinus surgery in the patient-based setting. CONCLUSION: These studies strengthen the evidence that simulation-based training, as part of a structured programme and incorporating predetermined proficiency levels, results in skills transfer to the operative setting.