The activating BRAF kinase mutation V600E occurs in ∼60% of human nevi and melanomas. A transgenic strain of zebrafish expressing BRAF-V600E under the control of the mitfa promoter on a p53 mutant background develops melanomas with 100% penetrance. Previously, we showed that a transposon-based vector, MiniCoopR, allows us to program melanocytes to express a candidate gene in a specialized zebrafish strain Tg(mitfa:BRAFV600E); mitfa-/-; p53-/-. This strain lacks melanocytes, but the lineage can be rescued by MiniCoopR injection at the 1-cell stage. This genetic system allows us to create cohorts of transgenic animals that express candidate genes and assay the effects on tumor development. Previous work identified two histone methyltransferases (HMTs), SETDB1 and SUV39H1, which cooperate with BRAF-V600E to accelerate the onset and severity of melanoma development. A number of HMTs display alterations in expression level or copy number in human cancers compared to normal tissues, and we tested a panel of methyltransferases using the MiniCoopR system. We hypothesize that HMTs promote tumorigenesis by altering the epigenetic program of melanocytes. In order to explore the effects on melanocyte specification and differentiation, we overexpressed and depleted candidate HMTs in zebrafish embryos and performed in situ hybridization for lineage-specific markers, such as crestin, sox10, mitfa, dct, and tyr. HMTs that exert specific developmental phenotypes were further characterized by performing chromatin immunoprecipitation (ChIP). Our goal is to correlate the processes affected in the developing embryo with the epigenetic program to elucidate the mechanism by which HMTs influence tumorigenesis. Additionally, we are developing a strain of zebrafish Tg(mitfa:BRAFV600E); mitfa-/-; alb-/-; p53-/-; Tg(mitfa:GFP) in which melanocytes rescued with MiniCoopR express GFP. These rescued melanocytes can be programmed to express candidate HMTs and allow us to visualize melanocyte and melanoma development in vivo. The work presented here will help correlate cancer phenotypes with specific chromatin-modifying enzymes that may be the basis for new drug development and biomarker discovery.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 5020. doi:1538-7445.AM2012-5020

©2012 American Association for Cancer Research
2012