Long-term ex vivo and in vivo monitoring of tumor progression by using dual luciferases.

We propose a new concept of tumor progression monitoring using dual luciferases in living animals to reduce stress for small animals and the cost of luciferin. The secreted Cypridina luciferase (CLuc) was used as an ex vivo indicator to continuously monitor tumor progression. On the other hand, the non-secreted firefly luciferase was used as an in vivo indicator to analyze the spatial distribution of the tumor at suitable time points indicated by CLuc. Thus, the new monitoring systems that use dual luciferases are available, allowing long-term bioluminescence imaging under minimal stress for the experimental animals.