In vitro radionuclide therapy and in vivo scintigraphic imaging of alpha-fetoprotein-producing hepatocellular carcinoma by targeted sodium iodide symporter gene expression.

PURPOSE: This study aimed to develop a gene expression targeting method for specific imaging and therapy of alpha-fetoprotein (AFP)-producing hepatocellular carcinoma (HCC) cells, using an adenovirus vector containing the human sodium/iodide symporter (hNIS) gene driven by an AFP enhancer/promoter.
METHODS: The recombinant adenovirus vector, AdAFPhNIS (containing the hNIS gene driven by human AFP enhancer/promoter) was prepared. After in vitro infection by the adenovirus, hNIS gene expression in AFP-producing cells and in AFP-nonproducing cells was investigated using (125)I uptake assay and semi-quantitative reverse transcription polymerase chain reaction (RT-PCR). The killing effect of (131)I on AdAFPhNIS-infected HCC cells was studied using an in vitro clonogenic assay. In addition, tumor-bearing mice were intravenously injected with the adenovirus, and scintigraphic images were obtained.
RESULTS: The expression of hNIS was efficiently demonstrated by (125)I uptake assay in AFP-producing cells, but not in AFP-nonproducing cells. AFP-producing HCC-targeted gene expression was confirmed at the mRNA level. Furthermore, in vitro clonogenic assay showed that hNIS gene expression induced by AdAFPhNIS infection in AFP-producing cells caused more sensitivity to (131)I than that in AFP-nonproducing cells. Injected intravenously in HuH-7 tumor xenografts mice by adenovirus, the functional hNIS gene expression was confirmed in tumor by in vivo scintigraphic imaging.
CONCLUSIONS: An AFP-producing HCC was targeted with an adenovirus vector containing the hNIS gene using the AFP enhancer/promoter in vitro and in vivo. These findings demonstrate that AFP-producing HCC-specific molecular imaging and radionuclide gene therapy are feasible using this recombinant adenovirus vector system.