Abstract A031 Early metastatic dissemination in a MYCN-driven zebrafish model of high-risk neuroblastoma

Abstract Neuroblastoma (NB) is a highly metastatic tumor of the peripheral sympathetic nervous system and is responsible for 10% of childhood cancer deaths. MYCN amplification remains one of the most substantial prognostic factors of a poor patient outcome and is detected in 20% of all NB patients. Patients are designated as high-risk (HR) when greater than 18 months of age with metastatic disease or MYCN-amplified. The overall survival rates for HR patients remain below 50% even with intensive multi-modal treatment. Despite the central role of metastatic disease in HR-NB treatment failure, little is known about the mechanisms that control metastatic dissemination. MYCNTT is an aggressive zebrafish model of HR-NB that highly expresses MYCN and has brightly EGFP-labeled tumor cells. A previous study from our lab shows that MYCNTT zebrafish spontaneously metastasize with micro-metastasis detected at 6 weeks post-fertilization (wpf) and that a larger number of metastatic foci were observed with the overexpression of metabolic enzyme dihydrolipoamide S-succinyltransferase. The primary tumor originates in the interrenal gland adjacent to the head kidney. We collected MYCNTT zebrafish at 3-, 3. 5-, and 4-wpf, fixed them in paraformaldehyde, and then the fish were frozen. Samples were then serially sectioned on a cryostat, mounted on slides, and stained with DAPI. The slides were imaged on a wide field fluorescent scope. As MYCNTT primary tumors begin to grow from cells within the interrenal gland at 3wpf, they are isolated from the kidney structures within the head kidney. By 4wpf, MYCTTT primary tumors have more than doubled in size and have surrounded the renal corpuscle in 75% of fish. These renal corpuscles became abnormal: dilated, discontinuous lining of Bowman’s capsule, the vessles of the glomerulus have collapsed, and the Bowman’s space have been invaded by tumor cells interacting with the glomerular tuft. Additionally, disseminated tumor cells (DTC) were first identified at 4wpf at sites common for metastasis zebrafish models of NB (eyes, gills, spleen). DTC were only observed when the primary tumor in MYCNTT zebrafish has surrounded the renal corpuscle. These results demonstrate that the glomerular tuft is the vascular source for hematogenous dissemination of MYCNTT zebrafish. Our data also shows that metastatic dissemination is an early event in MYCNTT tumorigenesis. The MYCNTT zebrafish model will provide insight and new avenues of investigating the metastatic process in NB, such as, understanding the genetic differences between the primary tumor and metastasis; elucidating the factors that drive tumor invasion and determining the fates of DTC (e. g. , dormancy). Citation Format: Kyle Woodward, Borum Ryu, Lauren Temple, Brian Tran, Perla Luna, Nicole Anderson. Early metastatic dissemination in a MYCN-driven zebrafish model of high-risk neuroblastoma abstract. In: Proceedings of the AACR Special Conference in Cancer Research: Advances in Pediatric Cancer Research; 2024 Sep 5-8; Toronto, Ontario, Canada. Philadelphia (PA): AACR; Cancer Res 2024;84 (17 Suppl): Abstract nr A031.