While these issues are being addressed, genomic pursuits in zebrafish can focus on modalities that are more robust to nuances in alignment, such as genomic copy number changes and transcriptome profiles based on RNA-seq. The latter strategy provides the additional advantage of capturing a wider range of aberrations — important given the heterogeneity — that together UK-371804 converge on a single expression phenotype. This and optimization of available tools will provide researchers far greater scope for evaluating the relevance of zebrafish cancer

and in prescribing new targets and strategies for investigating the human disease. The zebrafish field has seen major growth over the past 10 years, as rapid application of transgenic and chemical screening techniques

KU-60019 purchase have placed the fish in a unique category of cancer models. But while creating and analyzing models of human cancer is useful, it ultimately is not significantly advantageous to that done in mouse models. For the fish to offer truly novel and important insights into human cancer will require major innovations in technology and scale. Several areas are particularly amenable to study in the zebrafish, as outlined below (Figure 1). It is increasingly recognized that most human cancers are wildly heterogeneous at genetic, and likely, epigenetic, levels. To fully capture this complexity will require in vivo models that can express not just one to four altered genes, but potentially dozens. The increasing sophistication in making knockouts Histamine H2 receptor using TALENS [ 49 and 49] and the Cas9/CRISPr [ 50] genome editing system has made it possible to target nearly any candidate cancer gene in the in vivo setting. Although CRISPr was initially thought to be primarily useful for generating germline mutations [ 50 and 51], more recent work has highlighted its capacity for inducing somatic, biallelic disruptions in the F0 injected fish [ 52]. This is a tremendous advantage in zebrafish, since thousands of embryos per day can be generated, each of which can conceptually be injected with a CRISPr and phenotypes directly assessed without going to the

next generation. In a typical fish facility containing 2000–10 000 adult pairs of fish, the capacity to test hundreds of candidate genes serially or in parallel dwarfs what can be achieved in mouse models. It seems likely that large-scale genetic screens using this methodology in zebrafish will be forthcoming in the near future, complementing what has been done using ENU screens. Traditionally it has been difficult to perform large-scale chemical screens in vivo. However, numerous studies have now shown that the zebrafish is highly amenable to large-scale screens, testing thousands of compounds using detailed, in vivo phenotypic readouts. Although the majority of these screens have relied upon ‘proxy’ embryonic phenotypes (i.e.