A novel interleukin-13 receptor alpha 2-targeted hybrid peptide for effective glioblastoma therapy

We previously designed and reported a novel class of drugs, namely hybrid peptides, which are chemically synthesized and composed of a targeted binding peptide and a lytic-type peptide containing cationic amino acid residues that cause cancer cell death. In the present study, we screened for peptides that bind to interleukin-13 receptor alpha 2 (IL-13R alpha 2) by using a T7 random peptide phage display library system and isolated several positive phage clones. The A2b11 peptide, which was one of the positive clones, was shown to bind to IL-13R alpha 2 protein by Biacore analysis and a binding assay using glioblastoma (GB) cell lines. This peptide was linked with a lytic peptide containing a linker sequence to form the IL-13R alpha 2-lytic hybrid peptide. The IL-13R alpha 2-lytic hybrid peptide showed cytotoxic activity against GB cell lines in vitro. The IL-13R alpha 2-lytic hybrid peptide also affected Akt and Erk1/2 activation following treatment with interleukin-13 and induced rapid ATP dynamics in GB cells. Anti-tumor activity of the IL-13R alpha 2-lytic hybrid peptide was observed in vivo after intratumoral injection in a mouse xenograft model of human GB cells. These results suggest that the IL-13R alpha 2-lytic hybrid peptide might be a potent therapeutic option for patients with GB.