Engraftment of allotransplantated tumour cells in adult rag2 mutant Xenopus tropicalis

Modelling human genetic diseases and cancer in lab animals has been greatly aided by the emergence of genetic engineering tools such as TALENs and CRISPR/Cas9. We have previously demonstrated the ease with which genetically engineered Xenopus models (GEXM) can be generated. This included the induction of autochthonous tumour formation by injection of early embryos with Cas9 recombinant protein loaded with sgRNAs targeting multiple tumour suppressor genes. What has been lacking so far is the possibility to propagate the induced cancers via transplantation. In this paper we describe the generation of a rag2-/- knock-out line in Xenopus tropicalis that is deficient in functional T- and B-cells. This line was validated by means of an allografting experiment with a primary tp53-/- donor tumour. In addition, we optimized available protocols for sub-lethal gamma irradiation of X. tropicalis froglets. Irradiated animals also allowed stable, albeit transient, engraftment of transplanted tp53-/- tumour cells. The novel X. tropicalis rag2-/- line and the irradiated wild type froglets will further expand the experimental toolbox in this diploid amphibian, and help to establish it as a versatile and relevant model for exploring human cancer.