82 A.A. Hayes-Jordan

different animal models and several different ways to study human disease in animals. This is in no way comprehensive, but covers some of the more frequently used models.

Appropriate animal committee permission should be sought for all animal model research.

Transgenic Models

The quintessential animal model for transgenic mice is the RIP-TAg model developed by Doug Hanahan. This model was developed in the 1980s1 and continues, after over 30 years to sustain his research including hundreds of manuscripts pub- lished in peer review journals, continuous NIH funding for 30 years, and many articles in Cell, Nature and Science. Transgenic mice carrying oncogenes that reproducibly elicit tumors of specific cell types have provided a new format for studying multistep tumorigenesis. In one of these models, transgenic mice expressing an oncogene in the cells of the pancreatic islets heritably recapitulate a progression from normality to hyperplasia to neoplasia.Angiogenic activity first appears in a subset of hyperplastic islets before the onset of tumor formation.A few hyperplastic islets become angiogenic in vitro at a time when such islets are neovascularized in vivo and at a frequency that correlates closely with subsequent tumor incidence,thus supporting the concept that induction of angiogenesis is an important step in carcinogenesis.

What Is a Transgene? and What Is a Transgenic

Mouse?

A transgene is an exogenous gene delivered into the genome of another organism. An exogenous gene is injected directly into an embryo or cells at early embryonic stage using a microscopic needle. In this particular model, the gene used is an insulin gene in order to directly target the beta cells of the islet of Langerhans of the pancreas and as such that’s where the tumors will develop. SV40 is a known oncogene, meaning it transforms any cell to which is introduced into a cancer cell.