RESUMEN
Arsenic trioxide (ATO) has been demonstrated to induce apoptosis in retinoblastoma cells, however, mechanisms responsible for this phenomenon are not fully understood. In the present study, we determined whether ATO induced apoptosis by abnormal expression of microRNA. In an apoptosis model of retinoblastoma cells subjected to 4 µM ATO for 72 hours, we found 14 miRNAs changed more than 2-fold by using miRNA microarray analysis. Most of these aberrantly expressed miRNAs were confirmed by quantitative RT-PCR. MiR-376a, a significantly down-regulated miRNA, was selected for further study. The overexpression of miR-376a resulting from miR-376a mimic transfection significantly inhibited ATO-induced apoptosis. By contrast, miR-376a deficiency resulting from miR-376a inhibitor transfection aggravated ATO-induced apoptosis. Using bioinformatic algorithms, caspase-3, a key apoptosis executioner, was predicted as a putative target of miR-376a. The quantitative RT-PCR showed no effects of miR-376a mimic or inhibitor on caspase-3 mRNA level. However, the amount of caspase-3 proteins was reduced by miR-376a mimic, whereas increased by miR-376a inhibitor. Furthermore, the luciferase reporter assay confirmed caspase-3 to be a target of miR-376a, and the apoptosis caused by miR-376a inhibitor were abolished by a caspase-3 inhibitor. These results suggest that ATO -induced apoptosis in retinoblastoma cells is part mediated by decreasing expression of miR-376a, which subsequently increased caspase-3 expression.
Asunto(s)
Antineoplásicos/farmacología , Apoptosis , Arsenicales/farmacología , MicroARNs/genética , Óxidos/farmacología , Retinoblastoma/patología , Trióxido de Arsénico , Biomarcadores de Tumor/genética , Western Blotting , Caspasa 3/metabolismo , Proliferación Celular , Humanos , Luciferasas/metabolismo , Análisis de Secuencia por Matrices de Oligonucleótidos , ARN Mensajero/genética , Reacción en Cadena en Tiempo Real de la Polimerasa , Retinoblastoma/tratamiento farmacológico , Retinoblastoma/genética , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa , Células Tumorales CultivadasRESUMEN
It is well known that prostaglanding are biological mediators which are closely related to inflammation and immunity. To explore the role of PGE2 and PGF2 alpha in inflammation and immunity of human palatine tonsils, the levels of PGE2 and PGF2 alpha in diseased tonsils from 62 patients were measured. It is suggested that PGE2 and PGF2 alpha are present in the tonsillar tissue as inflammatory mediators. The levels of PGE2 and PGF2 alpha may be regarded as the major indicators of activation in chronic tonsillitis and represent the immunologic function of the palatine tonsils to a certain degree. The impairment of the ability of immunologic response in tonsils by inflammation may be related to PGE2. The more severe the inflammation, the more hazardous to the local immunologic defence of tonsils is. It is possible that PGE2 plays an important role in this respect.