EPO Signaling Promotes Therapy Resistance and Defines a Subtype of High‐Risk Neuroblastoma

Abstract

High‐risk neuroblastoma (NB) is one of the most aggressive childhood tumors that lacks effective treatment. Targeted drugs, such as receptor tyrosine kinase (RTK) inhibitors, have shown potential in treating high‐risk NB, but their efficacy is likely impaired by the cancer cells’ ability to adapt to drugs. Unlike other cancers, NB has a very low frequency of recurrent mutations, and only a few of them, such as MYCN amplification, can be used as prognostic markers. Here we reasoned that activation of growth factor signaling could promote NB therapeutic resistance and NB progression. We performed a transcriptome analysis of 60 NB tumor samples and found that enhanced growth factor signaling pathways such as erythropoietin (EPO), HGF, and NGF are associated with metastasis and poor response to therapy. We validated our results using data for more than 1000 NB samples from several independent patient cohorts and showed that high EPO receptor (EPOR) expression is a robust marker for NB poor prognosis and high relapse occurrence. Notably, EPOR expression does not depend on MYCN amplification and can be potentially used as a prognostic marker for MYCN‐non‐amplified high‐risk NB. We developed a new computational method based on gene set analyses to predict gene‐associated biological processes that drive the NB progression. This method proposes a novel strategy for NB risk stratification based on growth factor‐related gene sets. In a therapeutic setting, receptor tyrosine kinase inhibitors potentiate NB cells to EPO and NGF stronger pro‐survival action by increasing the receptors expression and basal ERK activity levels. ERK activity was measured on a single cell level using kinase translocation reporter, and receptor expression changes were measured by RT‐PCR and confirmed by antibody staining. Our research provides new insights into the importance of growth factor signaling in NB progression and highlights growth factor‐driven NB subtypes’ existence.