Identification of a Glypican-3-Binding Peptide for In Vivo Non-Invasive Human Hepatocellular Carcinoma Detection

Early and accurate detection of hepatocellular carcinoma (HCC) is essential to improve the prognosis of patients and reduce the morbidity of surgical therapy. Glypican-3 (GPC3) is a protein abnormally expressed in HCC that has been identified as a serological and histochemical HCC marker. A novel peptide that specifically recognizes GPC3 will facilitate early detection of HCC and guide the treatment strategy. Herein, phage display screening technology is utilized to obtain a GPC3 binding peptide (GBP) using HCC cells expressing GPC3 in varying abundances. After seven rounds of panning, a peptide with sequence of THVSPNQGGLPS is identified with 735.2 +/- 53.6 x 10(-9) m affinity to GPC3. The ability to target GPC3 in vivo is evaluated by intravenous injection of GBP labeled with a near-infrared dye, Cy5.5, into a HCC tumor-bearing mouse model. Significant high tumor accumulation (tumor/muscle ratio: 6.49 +/- 0.55) of Cy5.5-GBP in HepG2 tumors is observed compared with that of the low GPC3 expressing prostate cancer cell line, PC3 (tumor/muscle ratio: 1.15 +/- 0.32). By targeting GPC3, GBP differentiates tumor tissues from normal liver tissues in patients, suggesting a great clinical translation potency of GBP. Collectively, GBP demonstrates great potential for HCC detection via fluorescent imaging or histological staining.