We examined the gene expression signature of zebrafish brain tumors induced by somatic inactivation of the retinoblastoma tumor suppressor rb1 to determine the similarity with human CNS primitive neuroectodermal tumors (PNETs). Childhood CNS PNETs are aggressive tumors characterized by undifferentiated cells with features of the embryonic neuroepithelium. Previously our histological analysis showed the majority of zebrafish rb1- lesions were proliferative neuroectodermal-like tumors composed of neoplastic cells with small hyperchromatic nuclei that form rosettes. To obtain the transcription profile of the zebrafish rb1- tumors, RNA-Seq was performed on 10 tumors from fish ranging in age from 3.5 to 10 months of age. Duplicate RNA-Seq libraries were synthesized for each tumor and multiplex sequenced on an Illumina HiSeq NextGen Sequencer at the Genome Sequencing Core, Kansas University. Our initial gene expression profiling of the zebrafish rb1- brain tumors revealed a molecular signature consistent with an undifferentiated tumor phenotype. In each zebrafish tumor sample, standard markers of neuronal differentiation (sypa, sypb, neurod1/2, neurog1/2) and glial differentiation (GFAP, S100β) were not significantly expressed. In contrast, the neural stem/progenitor marker sox2 was highly expressed in all tumors, consistent with the primitive neuroectodermal-like tumor histology. Comparison with human childhood CNS-PNET gene expression analysis revealed a similar profile. Four of the nine genes that define the human oligoneural (group 2) molecular subgroup (olig2, bcan, sox8b, sox10 and ascl1) described by Picard et al, 2012 were highly expressed in the zebrafish tumors. Together, the data indicate the zebrafish brain tumors induced by somatic inactivation of rb1 model human CNS PNETs. Additional gene expression, pathway, and cross-species comparative analyses are in progress. The zebrafish rb1- tumor model will be useful for investigating the molecular pathways driving the aggressive and undifferentiated features of CNS PNETs.

Citation Format: Maura A. McGrail, Staci L. Solin, Jeffrey A. Haltom, Laura E. Schultz, Jeffrey J. Essner, Heather R. Shive. Expression profiling of zebrafish rb1- neuroectodermal-like brain tumors: A new model of CNS PNETs. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 4179.