Anti-GPC3 single-chain scFv antibody acts as an agent for radio-immunoimaging in diagnosing hepatocellular carcinoma

Glypican-3 (GPC3) over-expresses in hepatocellular carcinoma (HCC), but not expresses or under-expresses in normal adult hepatocytes. Therefore, GPC3 acts as a potential target for diagnosis and treatment of HCC. This study aimed to conduct radio-immunoimaging using GPC3 as a target in order, and to explore its potential for diagnosing and treating HCC. Humanized single-chain antibody scFv for HCC was established using phage antibody library. E.coli HB2151 was infected with recombinant phage antibodies that are considered to be strongly positive by phage ELISA. Then, the soluble antibodies were obtained post IPTG induction. Soluble antibodies were detected using SDS-PAGE assay. Anti-GPC3 single-chain antibodies were labeled using ¹³¹I, and then the distribution of radioactive markers in nude mice were analyzed in vivo by radio-immunoimaging. The results indicated that the size of soluble scFv products was 30 kD after purifying anti-GPC3 scFv antibodies that are successfully screened from phage antibody library. Anti-GPC3 phage antibodies could specifically bind to HCC cells. The ratios of radioactive tumor/blood and tumor/muscle for ¹³¹I labeled anti-GPC3 monoclonal antibodies were increased gradually, achieving the highest at 48 h. Radio-immunoimaging showed that the radioactive uptake of tumor sites remained the strongest at 48 h, and the ratio of target to non-target was the highest. In conclusion, the established anti-GPC3 scFv antibody had the potential to become an agent for radio-immunoimaging in diagnosing HCC and act as a targeted antibody for further radio-immunotherapy of HCC.