Generation of Novel Immunocompetent Mouse Cell Lines to Model Experimental Metastasis of High-Risk Neuroblastoma

SIMPLE SUMMARY: Neuroblastoma (NB) is the most common extracranial solid pediatric cancer, with highly observed metastasis at diagnosis. Primary NBs generally have favorable outcomes with current therapies; however, high-risk, metastatic NBs are resistant and result in relapsed disease. Patients with metastatic NBs, thus, have a lower overall survival. Thus, to develop effective therapies for metastatic NBs, it is essential to better understand the biology of metastasis in NB. This requires the utilization of pre-clinical animal models, importantly, immunocompetent models that have an intact immune system and better reflect the disease physiology. However, currently, there are few good animal models available for studying HR-NB metastasis. This study aimed to generate efficient and appropriate mouse models to study HR-NB metastasis. Our newly developed and validated mouse cell lines are relevant and promising tools to study (high-risk) HR-NB metastasis and identify novel therapeutic targets for metastatic NBs; thus, they could benefit the NB research community. ABSTRACT: NB, being a highly metastatic cancer, is one of the leading causes of cancer-related deaths in children. Increased disease recurrence and clinical resistance in patients with metastatic high-risk NBs (HR-NBs) result in poor outcomes and lower overall survival. However, the paucity of appropriate in vivo models for HR-NB metastasis has limited investigations into the underlying biology of HR-NB metastasis. This study was designed to address this limitation and develop suitable immunocompetent models for HR-NB metastasis. Here, we developed several highly metastatic immunocompetent murine HR-NB cell lines. Our newly developed cell lines show 100% efficiency in modeling experimental metastasis in C57BL6 mice and feature metastasis to the sites frequently observed in humans with HR-NB (liver and bone). In vivo validation demonstrated their specifically gained metastatic phenotype. The in vitro characterization of the cell lines showed increased cell invasion, acquired anchorage-independent growth ability, and resistance to MHC-I induction upon IFN-γ treatment. Furthermore, RNA-seq analysis of the newly developed cells identified a differentially regulated gene signature and an enrichment of processes consistent with their acquired metastatic phenotype, including extracellular matrix remodeling, angiogenesis, cell migration, and chemotaxis. The presented newly developed cell lines are, thus, suitable and promising tools for HR-NB metastasis and microenvironment studies in an immunocompetent system.