RESUMEN
SMARCA4 is the catalytic subunit of the SWI/SNF chromatin-remodeling complex, which alters the interactions between DNA and histones and modifies the availability of the DNA for transcription. The latest deep sequencing of tumor genomes has reinforced the important and ubiquitous tumor suppressor role of the SWI/SNF complex in cancer. However, although SWI/SNF complex plays a key role in gene expression, the regulation of this complex itself is poorly understood. Significantly, an understanding of the regulation of SMARCA4 expression has gained in importance due to recent proposals incorporating it in therapeutic strategies that use synthetic lethal interactions between SMARCA4-MAX and SMARCA4-SMARCA2. In this report, we found that the loss of expression of SMARCA4 observed in some primary lung tumors, whose mechanism was largely unknown, can be explained, at least partially by the activity of microRNAs (miRNAs). We reveal that SMARCA4 expression is regulated by miR-101, miR-199 and especially miR-155 through their binding to two alternative 3'UTRs. Importantly, our experiments suggest that the oncogenic properties of miR-155 in lung cancer can be largely explained by its role inhibiting SMARCA4. This new discovered functional relationship could explain the poor prognosis displayed by patients that independently have high miR-155 and low SMARCA4 expression levels. In addition, these results could lead to application of incipient miRNA technology to the aforementioned synthetic lethal therapeutic strategies.
Asunto(s)
ADN Helicasas/metabolismo , Regulación Neoplásica de la Expresión Génica , Neoplasias Pulmonares/diagnóstico , Neoplasias Pulmonares/genética , MicroARNs/metabolismo , Proteínas Nucleares/metabolismo , Factores de Transcripción/metabolismo , Dominio Catalítico , Línea Celular Tumoral , Núcleo Celular/genética , Proliferación Celular , Ensamble y Desensamble de Cromatina , Clonación Molecular , ADN Helicasas/genética , Células HeLa , Secuenciación de Nucleótidos de Alto Rendimiento , Histonas , Humanos , MicroARNs/genética , Proteínas Nucleares/genética , Pronóstico , Reproducibilidad de los Resultados , Factores de Transcripción/genética , Regulación hacia ArribaRESUMEN
The objective was to quantify oxidative stress resulting from ischemia during the donation process, using malondialdehyde (MDA) measurement, and its modulation by the administration of melatonin. We designed a triple-blind clinical trial with donors randomized to melatonin or placebo. We collected donors by donation after brain death (DBD) and controlled donation after circulatory death (DCD), the latter maintained by normothermic regional perfusion (NRP). Melatonin or placebo was administered prior to donation or following limitation of therapeutic effort (LTE). Demographic variables and medical history were collected. We also collected serial measurements of MDA, at 60 and 90 min after melatonin or placebo administration. A total of 53 donors were included (32 from DBD and 21 from DCD). In the DBD group, 17 donors received melatonin, and 15 placebo. Eight DCD donors were randomized to melatonin and 13 to placebo. Medical history and cause for LTE were similar between groups. Although MDA values did not differ in the DBD group, statistical differences were observed in DCD donors during the 0-60 min interval: -4.296 (-6.752; -2.336) in the melatonin group and -1.612 (-2.886; -0.7445) in controls. Given the antioxidant effect of melatonin, its use could reduce the production of oxidative stress in controlled DCD.