Abstract A010: LMO1 drives multifocal disease and divergent tumor fates in MYC-driven zebrafish models of neuroblastoma

Abstract

Clinical outcomes for neuroblastoma (NB) range from spontaneous regression to aggressive progression despite intensive multimodal therapy. Infants younger than 18 months with metastatic disease are classified as MS NB and can undergo spontaneous regression without treatment, although the mechanisms underlying regression remain poorly understood. Neuroblastoma most commonly arises in the adrenal gland but can also originate in the neck, chest, abdomen, or pelvis, reflecting its neural crest-derived origin. NB is a MYC-driven malignancy in which MYCN is dysregulated in approximately 30% of patients, while c-MYC is overexpressed in about 10%. Genome-wide association studies have identified LMO1 as a susceptibility locus associated with metastatic disease and increased LMO1 expression. To investigate the role of LMO1 in NB initiation and progression, we utilized transgenic zebrafish models expressing MYCN or c-MYC under the dopamine β-hydroxylase (dβh) promoter. The aggressive MYCN_TT model develops GFP-labeled tumors arising from the interrenal gland (IRG), the zebrafish homolog of the adrenal gland. Strikingly, LMO1 overexpression in MYCN_TT fish resulted in simultaneous primary tumors within both the IRG and jaw region, demonstrating multifocal disease. Jaw tumors originated from expansion of dβh-positive cells in the ventral cranium as early as 3.5 days post-fertilization. Histologic analysis showed that both tumor sites consisted of small, undifferentiated tyrosine hydroxylase-positive neuroblasts, consistent with catecholaminergic neuroblastoma. Similarly, LMO1 overexpression in the c-MYC zebrafish model induced multifocal primary tumors. In addition to promoting multifocal disease, MYCN_TT;dβh zebrafish exhibited early metastatic dissemination and increased metastatic burden by 8 weeks of age. Longitudinal analysis revealed three distinct jaw tumor outcomes: spontaneous regression in 40% of fish by 15 weeks, prolonged stable disease in 7%, and progressive invasive disease in 53% by one year. Stable and progressive tumors accumulated senescent (β-gal+) tumor cells with minimal intratumoral immune infiltration, whereas regressing tumors displayed robust peritumoral immune infiltration accompanied by clearance of senescent cells. Collectively, these MYC-driven zebrafish models identify LMO1 as a driver of multifocal primary neuroblastoma and demonstrate striking tumor fate heterogeneity ranging from spontaneous regression to aggressive progression. The MYCN_TT;dβh and c-MYC;dβh models provide a powerful platform for elucidating the mechanisms underlying spontaneous regression and disease progression in metastatic neuroblastoma.