Why zebrafish ? Cancer in zebrafish ???

1. Why zebrafish? Cancer in zebrafish???

2. Can house a lot of genetically distinct lines in not a lot of space!

3. Isolated mutations in hundreds of genes which affect embryonic development

4. Inherited mutations in some genes predisposes fish – like humans! – to cancer

5. Transgenic Tumor Models Tissue-specific promoters driving oncogenes 15 days 24 days 34 days 65 days T cell acute lymphoblastic lymphoma rag2 promoter driving cmyc-gfpfusion

6. Inactivating mutation of tumor suppressor genes causes cancer in zebrafish as in humans. Overexpression and/or activating mutation of the same oncogenes that drive human cancer causes cancer in zebrafish. GENES and PATHWAYS responsible for tumor progression are conserved between people and fish What would WE like to answer…..?

7. Some chromosome arms or entire chromosomes are preferentially gained and lost in many human tumors But these genomic regions can contain hundreds, if not thousands of genes A FEW drivers are responsible for cancer MOST genes in these regions are just neighbors “along for the ride” (passengers)

8. Finding the relevant genes in recurrent Copy Number Alterations: Comparative Oncogenomics Commonly altered genes Commonly altered genes

9. Mouse code human

10. Mouse code human Zebrafish code human Shared “gene neighborhoods” are smaller between zebrafish and human than between mouse and human

11. Comparing genes gained or lost in both human and zebrafish tumors reduced the number of “candidate” driver genes in large human gains/losses to about 25% Zebrafish code human Shared “gene neighborhoods” are smaller between zebrafish and human than between mouse and human

12. Comparing genes gained or lost in both human and zebrafish tumors reduced the number of “candidate” driver genes in large human gains/losses to about 25% However – this still leaves a large number of genes and we need a way to functionally test each one’s potential role - in tumors - in animals

13. Genetically-engineered melanoma in zebrafish:1) Mutation in the tumor suppressor gene p53 2) Expresses mutant oncogenes commonly found in human melanoma (BRAF, GNAQ, GNA11)

14. Functional testing of cancer drivers Mosaic analysis: If you inject embryos at the one-cell stage with DNA or agents to create specific mutations, a subset of cells in the resulting animal will inherit that DNA or mutation modifier of gene X (gain or loss of function) 1) Do tumors arise faster? = cells with gene X mutated (heterozygous or homozygous tumor-prone genetic background 2) Do tumors contain programmed modification in gene X?