Abstract 3955: A primary cell-based assay to identify initiating oncogenic events in neuroblastoma

The pediatric cancer neuroblastoma (NBL) forms from immature cells of the sympathetic nervous system (SNS). A prominent category of high-risk NBL is MYCN amplification with loss of heterozygosity (LOH) at 1p36. This LOH includes the chromatin remodeling factor, CHD5, a proposed tumor suppressor of NBL and can include ARID1A, a component of the SWI/SNF chromatin remodeling complex. To identify genetic changes that cooperate with MYCN amplification in initiating NBL we developed an assay based on oncogenic transformation of neural crest cells (NCCs), the progenitors of the SNS. Isolation of NCCs from E9.5 mouse embryos resulted in a population that was ∼90% positive for the NCC markers p75, Sox10, and Ascl1, suggesting a highly enriched population. Next, we tested the ability of N-Myc infected NCCs to form tumors in vivo. In pilot experiments using NCCs with compromised p53, we obtained subcutaneous tumors following injection of NCCs in nude mice. Resulting tumors were diffusely positive for neuronal markers such as synaptophysin, MAP2, and Tyrosine hydroxylase (TH). Tumors also contained focal areas of divergent differentiation characteristic of melanoma, Schwannoma, and osteosarcoma, all cancers that can arise from NCC lineages. To our knowledge, this is the first report of cancer from transformed primary neural crest cells. To more closely model NBL genetics, we replaced loss of p53 with shRNA to knockdown CHD5 and ARID1A prior to N-Myc infection. Injection of the resulting NCCs also resulted in tumor formation in nude mice. Tumors were uniformly positive for neuronal markers including TH and Ascl1, as well as Phox2B, a marker of undifferentiated NBL, and with no evidence of other cancers. Future studies in understanding the interactions of N-Myc overexpression with loss of these chromatin remodeling factors should further increase our understanding of NBL development. Citation Format: Rachelle Olsen, Joel Otero, Zhirong Yin, Jesus Garcia-Lopez, Kevin Freeman. A primary cell-based assay to identify initiating oncogenic events in neuroblastoma. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 3955. doi:10.1158/1538-7445.AM2015-3955