Carcinogen-induced and Spontaneous Mouse Models
Decades of studies on the laboratory mouse have led to the knowledge that certain mouse strains are prone to developing certain cancers, and treatment strategies can be tested on mouse models. Other mice have been genetically engineered to have pre-disposing mutations that can be triggered to evade normal cellular control systems. Some of these mice will characteristically develop a specific tumor after exposure to a given carcinogen, or cancer-causing agent. The agent could be chemical, radiation, or even physical impacts that result in alterations and mutations that lead to uncontrolled cell growth. Combined strategically with appropriate strains or genetically altered mouse models with defects in various cellular pathways, carcinogen-induced models can be immensely informative.
Induced model systems
Examples of chemically-induced models systems abound. Digestive system cancer in mice, induced by polycyclic aromatic hydrocarbons, has been studied since the 1940s. Breast cancer studies have long relied on spontaneous and induced models. Some inbred and genetically engineered mice harbor mouse mammary tumor virus (MMTV) or other oncogenic viruses and mutations, which trigger mammary cancers in those models. Other treatments with chemicals or hormones can initiate cellular alterations in breast cancer model systems. Oral and lung cancers can be modeled with tobacco-specific carcinogenic compounds.
Some chemical agents may have broad-spectrum effects in mouse models. For example, cadmium has been shown to induce a range of cancers in animals. Arsenic has multiple impacts that can be observed in animal models. These may offer many leads on the general mechanisms of cellular alterations, as well as insights into tissue-specific features as well.
Radiation-induced cancers offer another route to understanding the mechanisms of cancer. Ultraviolet radiation can be used to study skin cancer development in mice. Ionizing radiation is known to cause leukemic changes in mice. Intriguing mouse strain-specific features of radiation effects may lead to increased understanding of the process of cancer development.
Physical agonists may play a role in some cancers. Asbestos fibers may elicit an effect on cells that may initiate cancerous alterations in multiple tissues, and can be studied in mice.
Studies invoking cancerous changes in mouse models help us to understand many of the environmental assaults that we face, and will aid in the development of effective treatments for resulting cancers. However, as with all models, these may vary somewhat from typical human cancer, and therefore conclusions should be drawn with awareness and understanding of the differences.