がん研究のマウスモデル

Mice share approximately 80% orthology in coding regions with humans and display similar anatomical, cellular, and molecular characteristics. They are easy to maintain and breed in the laboratory, making them ideal for studying how altered genes contribute to tumor development. These similarities allow researchers to identify cancer-critical genes likely relevant to human disease.

Transgenic mice are engineered to over-express potential cancer-causing genes integrated into their genome with an appropriate promoter. If over-expression of the gene leads to tumor development in the mouse, it indicates the oncogenic potential of that gene. This approach directly demonstrates whether a specific gene can initiate cancer in a living organism.

Most tumor suppressor genes play essential roles in early mouse development, so complete knockout mice may not survive to adulthood. Conditional mouse models inactivate a gene of interest only in targeted tissue cells or at specific developmental stages. This allows researchers to study tumor suppressor function without causing embryonic lethality.

Reporter mice are engineered to co-express a gene of interest, such as an oncogene, with a fluorescent or luminescent reporter gene. When the target gene is expressed, the cells simultaneously luminesce, allowing researchers to monitor abnormal cell proliferation in real time. This visual tracking helps identify when and where tumors initiate and progress.

In a xenograft mouse model, human tumor cells are transplanted into an immunocompromised mouse. Once the cells develop into an appropriately sized tumor, a drug is introduced and its effect on cancer cells is studied in vivo. This preclinical approach bridges the gap between cell culture studies and human clinical trials.

Xenograft models using immunocompromised mice do not truly represent conditions inside an actual patient because the host immune system is compromised. Humanized mice have been altered to carry human genes, cells, or tissues to mimic a functional human immune system. This advancement allows researchers to study tumor progression and immune responses more accurately.

Pre-clinical studies in mouse models serve as a critical step between in vitro cell culture studies and clinical studies in humans. They allow investigation of in vivo pharmacokinetics, toxicity, and anti-tumor efficacy of chemotherapeutic agents before drugs advance to clinical trials. This testing phase significantly reduces risk in human studies.