An Immunocompetent Murine Model of Metastatic Mammary Cancer Accessible to Bioluminescence Imaging

Background: Many areas of research, including gene and pharmacological therapeutics, would benefit from longitudinal in vivo monitoring methodologies. To investigate the feasibility of one such methodology, we developed a murine mammary cancer model amenable to sequential bioluminescent imaging of tumor growth and metastasis in living animals. Materials and Methods: Metastatic mouse mammary carcinoma BJMC3879 cells were transfected to stably express firefly luciferase and inoculated into immunocompetent female BALB/c mice. Results: Sequential analysis using bioluminescent imaging showed increasing photon counts correlated to expanding mammary tumor volumes; in addition, strong signals from axillary, mandibular, femoral, thoracic and abdominal regions in mice were histopathologically determined to be due to metastases, the majority of which occurred in lymph nodes and lungs. Conclusion: The bioluminescent mouse mammary cancer model we established provides a method for quantifiable longitudinal in vivo imaging that can be used in gene and pharmacological therapy applications. The ability to detect cancer metastasis and its location(s) in laboratory animals in vivo has direct translational relevance to such detection in the human clinical setting. In basic laboratory animal experimentation, biomedical imaging systems can also significantly reduce the number of animals required in longitudinal studies and increase the experimental data harvested for each animal (1). Imaging tools for