Swine in Biomedical Research Conference 2005, Chicago, IL. Abstract S1.
The transition from basic to clinical cancer research is hampered, to some extent, by the lack of model organisms similar to man. Specifically, animals that have a similar diet, metabolism, and anatomy would be of great valuable in assessing the effect of anti-cancer drugs on tumor development. One such animal is the pig, which being an omnivore, shares a similar metabolism with humans as well as having a comparable lifespan, body size, and anatomy. Indeed, the pig has long been used as a biomedical model for many human diseases, but has not been exploited for cancer research. We have recently found that many of the genetic events required to promote the tumorigenic growth of normal human cells in immuno-compromised mice are likewise required for the same process in pigs. Moreover, such genetically modified porcine cells also formed tumors when returned back to the syngenic host pig. While the immune system of the host pigs needed to be suppressed, likely due to a reliance on using human genes to drive the porcine cells to a tumorigenic state, these experiments provide proof-of-principle that, as in mice, porcine cells could be manipulated in culture to yield cancer cell lines that could be returned to the host animal. With the advent of animal cloning, a single tumorigenic cell line generated from a cloned pig could even be returned to a host of cloned animals, greatly expanding the utility of this model. Along the same lines of reasoning, we are also inducing tumors in cloned pigs with chemical carcinogens to generate cancer cell lines that could also be injected into other cloned animals. This ability to grow established genetically defined or chemically-induced tumor cell lines in cloned pigs could provide a robust and malleable system to not only study human cancer, but also to serve as a preclinical model of this disease in an animal that is similar, in many respects, to humans.