Abstract
The large size of the pig and its similarity in anatomy, physiology, metabolism, and genetics to humans make it an ideal platform to develop a genetically defined, large animal model of cancer. To this end, we created a transgenic “oncopig” line encoding Cre recombinase inducible porcine transgenes encoding KRASG12D and TP53R167H, which represent a commonly mutated oncogene and tumor suppressor in human cancers, respectively. Treatment of cells derived from these oncopigs with the adenovirus encoding Cre (AdCre) led to KRASG12D and TP53R167H expression, which rendered the cells transformed in culture and tumorigenic when engrafted into immunocompromised mice. Finally, injection of AdCre directly into these oncopigs led to the rapid and reproducible tumor development of mesenchymal origin. Transgenic animals receiving AdGFP (green fluorescent protein) did not have any tumor mass formation or altered histopathology. This oncopig line could thus serve as a genetically malleable model for potentially a wide spectrum of cancers, while controlling for temporal or spatial genesis, which should prove invaluable to studies previously hampered by the lack of a large animal model of cancer.
Highlights
A large animal model of cancer would be beneficial in settings requiring size, anatomy, metabolism, or genetics reflective of humans, such as for studies of noninvasive image-guided technologies, radiation oncology, drug metabolism, surgical training, technology development, to name but just a few [1,2]
Site-directed mutagenesis was used to introduce the oncogenic G12D mutation into the porcine KRAS cDNA. This mutation was chosen as an aspartic acid substitution accounts for over a third of the mutations at the G12 position in human cancers [7] and introducing this mutation into the endogenous murine Kras gene promotes tumorigenesis [8,20]
These two cDNAs were introduced into a Cre-inducible vector, yielding an expression construct containing the CAG promoter, followed by the aforementioned LSL sequence, KRASG12D, an IRES sequence to allow for bicistronic expression, TP53R167H and a poly A sequence (Fig 1a)
Summary
A large animal model of cancer would be beneficial in settings requiring size, anatomy, metabolism, or genetics reflective of humans, such as for studies of noninvasive image-guided technologies, radiation oncology, drug metabolism, surgical training, technology development (e.g., early detection screening), to name but just a few [1,2]. In this regard, the pig is an ideal large. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript
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