EIF4EBP1 is transcriptionally upregulated by MYCN and associates with poor prognosis in neuroblastoma.

Neuroblastoma (NB) accounts for 15% of cancer-related deaths in childhood despite considerable therapeutic improvements. While several risk factors, including MYCN amplification and alterations in RAS and p53 pathway genes, have been defined in NB, the clinical outcome is very variable and difficult to predict. Since genes of the mechanistic target of rapamycin (mTOR) pathway are upregulated in MYCN-amplified NB, we aimed to define the predictive value of the mTOR substrate-encoding gene eukaryotic translation initiation factor 4E-binding protein 1 (EIF4EBP1) expression in NB patients. Using publicly available data sets, we found that EIF4EBP1 mRNA expression is positively correlated with MYCN expression and elevated in stage 4 and high-risk NB patients. In addition, high EIF4EBP1 mRNA expression is associated with reduced overall and event-free survival in the entire group of NB patients in three cohorts, as well as in stage 4 and high-risk patients. This was confirmed by monitoring the clinical value of 4EBP1 protein expression, which revealed that high levels of 4EBP1 are significantly associated with prognostically unfavorable NB histology. Finally, functional analyses revealed that EIF4EBP1 expression is transcriptionally controlled by MYCN binding to the EIF4EBP1 promoter in NB cells. Our data highlight that EIF4EBP1 is a direct transcriptional target of MYCN whose high expression is associated with poor prognosis in NB patients. Therefore, EIF4EBP1 may serve to better stratify patients with NB.

Proliferation Assessment by Trypan Blue Exclusion in Ewing Sarcoma.

Cell proliferation is broadly defined as a process leading to an increase of cell number, essentially depending on a balance between cell cycle progression/cell division, cell death, and cellular senescence. Deregulation of cell proliferation is a key feature of cancer cells, making assessment of proliferation a central methodological issue in cancer research. Especially in Ewing sarcoma (EwS) that exhibit a high proliferative capacity, experimental assessment of proliferation in preclinical research plays an important role. Among the variety of applicable methods, trypan blue exclusion is described here as a robust, easy-to-perform, and cost-effective method to assess cell proliferation in an experimental setting.