Fig. 3

Comparing Tumor Invasion and Drug Response. (A) CNS-PNETs¹⁷ from the optic tectum or cerebellum are labeled with mCherry or GFP, respectively, processed into a single-cell suspension, mixed together at a 1:1 ratio, and co-transplanted into 2-dpf embryos. (B) A 6-dpf embryo co-transplanted with a mixed suspension of GFP-labeled cerebellar tumor cells and mCherry-labeled tumor cells from the optic tectum. Differences in the invasive properties of each tumor in the same recipient can be observed using fluorescence microscopy. In this example, mCherry-labeled tumor cells migrate more extensively than those labeled with GFP (arrows). (C) Timeline for drug treatment on embryos transplanted with tumor cells. (D) Images of representative animals at the end of the treatment regimen (8 dpf) and at 8 weeks post-treatment (8 wpf), with either a DMSO control or a 50 µM MEK inhibitor. Tumor burden can be measured by quantifying fluorescence, as described¹⁷. In this experiment, the growth of mCherry-labeled tumor cells is reduced in MEK inhibitor-treated embryos and translates into a durable response in the adult.