During tumour progression, brain tumour cells are exposed to metabolic stress, such as nutrient deprivation, due to abnormal tumour vasculature. The ability of tumour cells to respond and manage reduced nutrient availability has a strong impact on tumour outcome. The molecular pathways supporting metabolic adaptation of brain tumour cells to nutrient stress represent potential therapeutic targets which are still not well defined. We report that the translation elongation factor 2 (eEF2) kinase mediates a protective response under nutrient starvation by restraining mRNA translation at the step of elongation. In aggressive human tumour cells, such as medulloblastoma (MB) cells, ablation of eEF2K expression increases sensitivity to nutrient removal. In addition, gene expression analysis in patient samples show that eEF2K expression is upregulated in the most aggressive subgroup of MB, namely group 3, and that high eEF2K expression is strongly associated with poor survival in both MB and glioblastoma (GBM). In vivo, eEF2K overexpression confers resistance of tumour xenografts to calorie restriction. Finally, our data reveal that eEF2K is an evolutionarily conserved mediator of the physiological response to nutrient starvation, as genetic removal of eEF2K compromises survival of C. elegans in absence of nutrients. Overall, our works highlight a novel pro-survival factor which is hijacked by brain tumour cells to support their adaptation to nutrient stress. The potential for therapeutic targeting of eEF2 kinase in brain tumors will be discussed.
|Published - 2014