RESUMEN
Cancers with Ras mutations represent a major therapeutic problem. Recent RNAi screens have uncovered multiple nononcogene addiction pathways that are necessary for the survival of Ras mutant cells. Here, we identify the evolutionarily conserved gene enhancer of rudimentary homolog (ERH), in which depletion causes greater toxicity in cancer cells with mutations in the small GTPase KRAS compared with KRAS WT cells. ERH interacts with the spliceosome protein SNRPD3 and is required for the mRNA splicing of the mitotic motor protein CENP-E. Loss of ERH leads to loss of CENP-E and consequently, chromosome congression defects. Gene expression profiling indicates that ERH is required for the expression of multiple cell cycle genes, and the gene expression signature resulting from ERH down-regulation inversely correlates with KRAS signatures. Clinically, tumor ERH expression is inversely associated with survival of colorectal cancer patients whose tumors harbor KRAS mutations. Together, these findings identify a role of ERH in mRNA splicing and mitosis, and they provide evidence that KRAS mutant cancer cells are dependent on ERH for their survival.
Asunto(s)
Proteínas de Ciclo Celular/metabolismo , Proteínas Cromosómicas no Histona/genética , Secuencia Conservada , Evolución Molecular , Mutación/genética , Proteínas Proto-Oncogénicas/genética , Empalme del ARN/genética , Factores de Transcripción/metabolismo , Proteínas ras/genética , Ciclo Celular/genética , Línea Celular Tumoral , Supervivencia Celular/genética , Proteínas Cromosómicas no Histona/metabolismo , Cromosomas Humanos/metabolismo , Neoplasias Colorrectales/genética , Neoplasias Colorrectales/patología , Regulación Neoplásica de la Expresión Génica , Humanos , Oncogenes , Unión Proteica , Proteínas Proto-Oncogénicas p21(ras) , ARN Mensajero/genética , ARN Mensajero/metabolismo , Análisis de Supervivencia , Proteínas Nucleares snRNP/metabolismoRESUMEN
Acute osmotic fluctuations in the brain occur during a number of clinical conditions and can result in a variety of adverse neurological symptoms. Osmotic perturbation can cause changes in the volumes of intra- and extracellular fluid and, due to the rigidity of the skull, can alter intracranial pressure thus making it difficult to analyze purely osmotic effects in vivo. The present study aims to determine the effects of changes in osmolarity on SH-SY5Y human neuroblastoma cells in vitro, and the role of the actin-myosin network in regulating this response. Cells were exposed to hyper- or hypoosmotic media and morphological and cytoskeletal responses were recorded. Hyperosmotic shock resulted in a drop in cell body volume and planar area, a persisting shape deformation, and increases in cellular translocation. Hypoosmotic shock did not significantly alter planar area, but caused a transient increase in cell body volume and an increase in cellular translocation via the development of small protrusions rich in actin. Disruption of the actin-myosin network with latrunculin and blebbistatin resulted in changes to volume and shape regulation, and a decrease in cellular translocation. In both osmotic perturbations, no apparent disruptions to cytoskeletal integrity were observed by light microscopy. Overall, because osmotically induced changes persisted even after volume regulation occurred, it is possible that osmotic stress may play a larger role in neurological dysfunction than currently believed.