TM-04 * A TRANSGENIC ZEBRAFISH MODEL FOR GLIOMAS WITH MUTATIONS IN ISOCITRATE DEHYDROGENASE 1

Abstract

Isocitrate dehydrogenase 1 (IDH1) is a gene that is mutated in about 70-90% of grade II/III glioma patients. Unfortunately, there are very few good model systems for IDH-mutated tumors to functionally examine effects of IDH1 mutations and to test candidate inhibitors. We have therefore generated a transgenic zebrafish (Danio rerio) model expressing mutant IDH1 to create an in-vivo model system for studying IDH1 mutated tumors. IDH1R132H and IDH1wildtype constructs driven by a Nestin promoter were generated. These constructs were injected into fertilized zebrafish eggs at the one-cell stage. The generated transgenic fish were characterized at the transcriptional, proteomic, enzymatic and metabolomics level. All transgenic fish lines appeared healthy and produced offspring. Thus far, no tumors were observed. Introduced IDH1 wildtype and mutant expression was detected in a subset of cells in the mid-and hindbrain of central nerve system by immunohistochemistry in 1-5 dpf embryos. This temporal expression is consistent with activity of the Nestin promoter. Even though only a subset of cells (i.e. the Nestin+ cells) expressed mutant IDH1, D2-HG levels were approximately 4-10 fold higher than in the wildtype. The effect was specific for D2-HG as L2-HG in both transgenic zebrafish lines remained similar. No differences in collagen maturation or DNA methylation were observed. Treatment of the transgenic zebrafish with an IDH1 mutant inhibitor, AGI-5198, for up to three days resulted in a ∼2 fold reduction in the D2-HG level in the mutant zebrafish. The L2-HG level was not affected by lines for the use of drug screening. We have generated a transgenic zebrafish model system for IDH1 mutated tumors that can be used to examine pathway activation and be used for drug screening.