Use of transgenic mice in identifying chemopreventive agents

Cancer chemoprevention uses natural- or synthetic chemical compounds to reverse, suppress or to prevent one or more of the biological events leading to the development of cancer. Chemopreventive agents are classified as blocking or suppressing according to their action on either the initiation or promotion-progression phases in experimental models using carcinogen treated animals. Transgenic animal technology has resulted in a plethora of murine models for cancer research providing insight into the complex oncogenic events contributing to the loss of cell cycle control and tumourigenesis. Transgenic models also offer an important opportunity to identify and study both tumourigens and chemopreventive agents. However, so far chemoprevention has in such models only been investigated to a limited degree and primarily in models with inactivated tumour suppressor genes. Studies show that spontaneous tumour developing due to loss of p53 function may be offset by preventive measures. The preventive actions of retinoids and polyamine synthesis inhibitors have been studied in the PIM mouse susceptible to lymphoma development. Most chemopreventive studies have been performed on murine familial adenomatous polyposis (FAP) models, which carry one non-functional apc gene and develop multiple intestinal adenomas upon inactivation of the wild type allele. Particularly non-steroidal anti-inflammatory drugs NSAIDs, which block COX-2, but also food components such as n-3 fatty acids show promising chemopreventive effects in these models. Transgenic cancer models demonstrate a strong gene-environment interaction, which is promising for the development of chemopreventive strategies.