Role of Mouse in Cancer Research

Cancer is a complex disease where dynamic changes in multiple genes essential for diverse molecular pathways are involved in its initiation, progression, invasion and metastasis. The genes implicated in cancer include those involved in cell cycle control, apoptosis, DNA repair, ageing and immortalization, angiogenesis and metastasis. Activation of oncogenes, inactivation of tumour suppressor genes and alterations in micro RNA and other genes through sequential accumulation of mutations, combined with multiple cycles of clonal selection and evolution, facilitate the process of carcinogenesis. Mouse (Mus musculus) is widely used as an animal model for research and investigation of human disease, because of its genome similarity (20,000-25,000 genes are common), small body size and availability of large number of inbred strains. Transgenic mice generated to carry cloned oncogenes and knockout mice lacking tumor suppressing genes have provided good models for human cancer. Hundreds of these oncomice have been developed covering a wide range of cancers affecting most organs of the body and they are being refined to become more representative of human cancer. There are several thousand different strains of knockout mice. Many mouse models are named after the gene that has been inactivated. For example, the p53 knockout mouse is named after the p53 gene which codes for a protein that normally suppresses the growth of tumours by arresting cell division and/or inducing apoptosis. Humans born with mutations that deactivate the p53 gene suffer from Li-Fraumeni syndrome, a condition that dramatically increases the risk of developing bone cancers, breast cancer and blood cancers at an early age. The potential drugs or treatments can be tested against these mouse models.