Zebrafish rb1 brain tumors express an oligoneural precursor signature similar to human OLIG2+/SOX10+ CNS-PNET. (A) Zebrafish rb1 brain tumor model created by somatic targeting of rb1 exon 2 with CRISPR-Cas9 or TALENs. Gross brain tumors develop in the midbrain and hindbrain (red asterisks) of adults at 4-5 months of age. For transcriptome analysis, half of the tumor tissue was dissected from ten tumor-positive fish for RNA isolation. The remaining tissue was embedded for pathology and immunolabeling. (B) Heat maps of log2(FPKM) show differential gene expression in zebrafish rb1 brain tumor transcriptome of 120 genes in the human OLIG2+/SOX10+ CNS-PNET subtype. rb1 tumor RNA-Seq of ten biological replicates from ten individual tumor positive adults, and C RNA-Seq of two biological replicates of three pooled normal adult zebrafish brain, are shown. (C-L) Histological and immunolabeling of wild-type adult zebrafish pretectum/diencephalon (C-G) and tumor-containing brain tissue from transcriptome individual T2 (H,I) and T8 (J-L). Neoplastic cells in T2 tumor show small densely basophilic nuclei, consistent with primitive neuroectodermal-like tumors (H,I). In normal adult brain, Olig2, Sox2 and Sox10 labeling is restricted to cells at or adjacent to the ventricle (E-G). High levels of Olig2, Sox2 and Sox10 are detected in the neoplastic tissue in tumor T8. Phosphohistone H3-labeled mitotic cells are scattered throughout the lesion (J-L). Scale bars: 200 µm (C,H); 50 µm (E,F,G,J,K,L).
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