Studies of the Tumor Microenvironment in Pathogenesis of Neuroblastoma

Abstract : Neuroblastoma is the most common extra cranial solid tumor of childhood, and 45% of patients have high-risk tumors, nearly all of which are metastatic (stage 4) when diagnosed. Seventyone percent of metastatic (stage 4) neuroblastomas (mNBL) lack amplification of the MYCN oncogene. An intriguing observation about survival of patients with MYCN non-amplified mNBL (mNBL MNA) is the extreme variation based on age at diagnosis. Children diagnosed less than 18 months of age have greater than 90% overall survival (O.S.), while those diagnosed after 18 months of age have only 45% O.S. even with improvements in therapy during the past 20 years. Recently, our group has identified several inflammation-related genes correlating with age at diagnosis and outcome in this group of tumors. Our characterization of a recently described 100% penetrant transgenic murine neuroblastoma model (NBL-Tag) established lack of MYCN amplification using comparative genomic hybridization (aCGH). Remarkably, tumors are not detected by MRI until 13 weeks of life, but they then grow rapidly with liver and bone marrow metastasis by 20 weeks and demise by 28 weeks. Tumor growth coincides with IL6 becoming detectable and increasing in blood, and tumors exhibit high expression of IL-4, IL-6, and IL-10 and are infiltrated by TAMs (CD11b+, F4/80+) and B lymphocytes (B220+,CD19+/IgM+). Immunofluorescence analyses demonstrate immunoglobulin deposition within the tumors. These data identify the NBL-Tag mice as the only known transgenic murine model for aggressive human mNBL MNA. Importantly, the pro-inflammatory microenvironment of the NBLTag tumors mimics that observed in human neuroblastoma. Our specific aims will allow us to identify the significance of a pro-inflammatory tumor microenvironment on neuroblastoma pathogenesis.