Production of transgenic mice expressing firefly luciferase gene controlled by α-fetoprotein enhancer/promoter

Objectives Development of a small animal imaging system for hepatocellular carcinoma(HCC) specific reporter gene expression will enable us to image carcinogenesis or monitor therapeutic intervention of HCC in vivo. Fetoprotein(AFP) is a fetal protein which is not expressed after birth but is re-expressed in HCC. In this study, we developed a firefly luciferase(fLuc) transgenic mouse in which fLuc expression is controlled by AFP enhancer/promoter only in AFP producing cells.

Methods pGL3-AFPfLuc containing fLuc gene driven by AFP enhancer/promoter was constructed. For the verification of this system pGL3-AFPfLuc was transiently transfected to AFP-producing HCC cells(HuH-7) and AFP-non producing cells(C6) using lipofectamine. The expression of fLuc gene was measured by fLuc activity assay. pGL3-AFPfLuc was used for the production of fLuc-transgenic mice. The propriety of the transgenic mouse model was evaluated by in vivo bioluminescent imaging (BLI) in fetus or neonatal mice.

Results After transfection of pGL3-AFPfLuc, the fLuc activity was observed in AFP-producing HCC cells, but not in AFP-nonproducing cells. Eleven positive founders among 110 founders were obtained using genomic PCR typing and 8 of 11 lines were male. Eight male genotype positive founders were mated with wild type female mice and its progenies of 3 lines(39, 59 and 78) showed strong bioluminescence signal in their liver region at 1 day after birth as well as fetus. Normal fetus and newborn mice did not express fLuc in their liver region.

Conclusions We developed a transgenic mouse model to image AFP-producing cells with BLI using AFP enhancer/promoter and fLuc.