The HER2-binding Affibody Molecule (ZHER2:342)2 Increases Radiosensitivity in SKBR-3 cells

Abstract

We have previously shown that the HER2-specific affibody molecule (ZHER2:342)2 inhibits proliferation of SKBR-3 cells. Here, we continue to investigate its biological effects in vitro by studying receptor dimerization and clonogenic survival following irradiation. We found that (ZHER2:342)2 sensitizes the HER2-overexpressing cell line SKBR-3 to ionizing radiation. The survival after exposure to (ZHER2:342)2 and 8 Gy (S8Gy 0.006) was decreased by a factor of 4 compared to the untreated (S8Gy 0.023). The low HER2-expressing cell line MCF-7 was more radiosensitive than SKBR-3 but did not respond to (ZHER2:342)2. Treatment by (ZHER2:342)2 strongly increased the levels of dimerized and phosphorylated HER2 already after 5 minutes of stimulation. The monomeric ZHER2:342 does not seem to be able to induce receptor phosphorylation and dimerization or sensitize cells to irradiation