Hepatocellular carcinoma targeted reporter gene expression using alpha-fetoprotein (AFP) enhancer/promoter in mouse model

Objectives This study aims to develop reporter gene targeting method for AFP-producing hepatocellular carcinoma (HCC) specific imaging and therapy using adenovirus vector containing reporter gene driven by AFP enhancer/promoter.

Methods The recombinant adenovirus vectors, AdAFPfLuc and AdAFPhNIS (containing firefly luciferase gene and human sodium/iodide symporter gene, respectively, driven by human AFP enhancer/promoter) were prepared. After an in vitro infection by adenovirus, the expression of reporter genes was confirmed by luciferase assay, I-125 uptake assay and RT-PCR analysis in AFP-producing cells (HuH-7 and HepG2), and in AFP-nonproducing cells (SK-Hep-1, Chang, and C6). The tumor-bearing mice were intravenously injected with adenovirus, and bioluminescent and scintigraphic images were obtained.

Results The expression of fLuc or hNIS was demonstrated efficiently by luciferase assay or I-125 uptake assay in AFP-producing cells, but not in AFP-nonproducing cells. Tumor specific reporter gene expression was confirmed on mRNA level by RT-PCR analysis. Injected intravenously in HuH-7 tumor bearing mice, adenovirus drove expression of a functional fLuc or hNIS protein by only HuH-7 tumor and allowed marked luciferase or hNIS activity, whereas AdCMVLuc drove fLuc expression only in liver.

Conclusions AFP-producing HCC was targeted with adenovirus vector containing reporter gene using AFP enhancer/promoter in vitro and in vivo. These findings demonstrate that AFP-producing HCC specific molecular imaging are feasible using this recombinant adenovirus vector system.