Cancer modeling by Transgene Electroporation in Adult Zebrafish (TEAZ)

Abstract

Transgenic animals are invaluable for modeling cancer genomics, but often require complex crosses of multiple germline alleles to obtain the desired combinations. Zebrafish models have advantages in that transgenes can be rapidly tested by mosaic expression, but typically lack spatial and temporal control of tumor onset, which limits their utility for the study of tumor progression and metastasis. To overcome these limitations, we have developed a method referred to as Transgene Electroporation in Adult Zebrafish (TEAZ). TEAZ can deliver DNA constructs with promoter elements of interest to drive fluorophores, oncogenes or CRISPR-Cas9-based mutagenic cassettes in specific cell types. Using TEAZ, we created a highly aggressive melanoma model via Cas9-mediated inactivation of Rb1 in the context of BRAFV600E in spatially constrained melanocytes. Unlike prior models that take ∼4 months to develop, we found that TEAZ leads to tumor onset in ∼7 weeks, and these tumors develop in fully immunocompetent animals. As the resulting tumors initiated at highly defined locations, we could track their progression via fluorescence, and documented deep invasion into tissues and metastatic deposits. TEAZ can be deployed to other tissues and cell types, such as the heart, with the use of suitable transgenic promoters. The versatility of TEAZ makes it widely accessible for rapid modeling of somatic gene alterations and cancer progression at a scale not achievable in other in vivo systems.

From gene to treatment: supporting rare disease translational research through model systems

“…Now, zebrafish have particularly benefited from the advent of Cas endonuclease-driven genome editing. Three DMM papers in the describe the generation of precise genetic models of human diseases, exploit error-prone repair after endonuclease activity and insert mutagenic cassettes into specific cells using the CRISPR/Cas system (Tessadori et al, 2018; Boel et al, 2018; Callahan et al, 2018). These techniques have greatly expanded the repertoire for genetic experimentation in the fish and will undoubtedly empower rare disease modelling.…”

The Zebrafish as an Emerging Model to Study DNA Damage in Aging, Cancer and Other Diseases

“…The number of models (including mutant and reporter lines) is growing (see Figure 1 for a network of DDR-related zebrafish tools, linked to ZFIN pathway database). This is mostly due to the recent addition of somatic transgenics (reviewed in Idilli et al, 2017; Callahan et al, 2018) and somatic knock outs (Ablain et al, 2015; Di Donato et al, 2016). Reporters of DDR and different DNA repair systems are being perfected, while more tools for detection (antibodies, techniques, etc.)…”

Modeling hematopoietic disorders in zebrafish

“…Limitations that still need to be overcome involve the concurrent and selective expression of oncogenes in adult zebrafish tissues, enabling improved phenocopying of human disorders. In this regard, an interesting novel approach has been recently demonstrated, allowing injection of DNA constructs in adult fish at a certain time point and at any specific location (Callahan et al, 2018). This system, called ‘transgene electroporation in adult zebrafish’ might become useful for hematopoietic diseases, e.g.…”