Glypican-3 Aptamer Has Potential as a New Targeted Therapy for Hepatocellular Carcinoma = Glypican-3 Aptamer Has Potential as a New Targeted Therapy for Hepatocellular Carcinoma

다국어 초록 (Multilingual Abstract)

Aims: Aptamers are single-stranded synthetic oligonucleotides binding to overexpressed molecular targets on cancer cells. Glypican-3 (GPC3), a cell surface oncofetal protein that is highly expressed in hepatocellular carcinoma (HCC), has emerged as a novel therapeutic target. We developed aptamers targeting GPC3 and assessed those therapeutic potentials in the treatment of HCC by evaluating the binding affinity to HCC cells and anti-tumor efficacy. Methods: GPC3 expression on the surface of HCC cells (SNU-475, SNU-761, Huh7, and SNU-3058) was assessed by immunofluorescence staining. Flow cytometry was performed to determine the binding affinity of the GPC3 aptamers, which were generated through systematic evolution of ligands by exponential enrichment (SELEX) method, to HCC cells. Cell proliferation was studied using the MTS assay, and signaling pathways were explored by immunoblot analysis. Results: GPC3 was highly expressed in all HCC cell lines tested. Fourteen SELEX-derived GPC3 aptamers (representative aptamer; Kd, 4.5 ± 1.0 nM; Bmax, 0.45 fmol/mg protein) were evaluated using flow cytometry for selection of high-affinity aptamers to HCC cells. Among GPC3 aptamers analyzed, four GPC3 aptamers which showed high affinity to SNU-761 (~18.3%) or Huh7 cells (~37.0%) were selected for MTS assay. Treatment with GPC3 aptamers significantly suppressed HCC cell growth under normoxic (SNU-761 cells, P=0.038 and P=0.005; Huh7 cells, P=0.011 and P=0.013) and hypoxic (SNU-761 cells, P=0.019 and P=0.054; Huh7 cells, P=0.031 and P=0.011) conditions compared to control aptamers. Yes-associated protein (YAP), an oncogene which triggers cancer cell proliferation, was suggested to be down-stream signal of GPC3. GPC3 aptamers catalyzed inactivation of YAP by promoting its phosphorylation, leading to attenuation of HCC cell proliferation. Conclusions: We demonstrated that newly synthesized GPC3 aptamers can bind to HCC cells with high affinity and suppress HCC cell growth via inactivation of YAP. Further investigation of GPC3 aptamers as a novel targeted therapy for HCC is warranted.