HER3 Activation Mediated By ROS Increases Radioresistance Of Esophageal Squamous Cell Carcinoma

Objective To investigate the hypothesis that accumulation of reactive oxygen species(ROS)regulated the activation of HER3 which might confer radioresistance to esophageal squamous cell carcinomas in vivo and in vitro.Methods CCK8 assay,clonogenic assay,flow cytometry and immunofluorescence were performed to analyze cell proliferation,colony formation,apoptosis,cell cycle and DNA damage respectively.Nude mice inoculated subcutaneously with KYSE-150 cells were used to examine the sensitizing effects of knockdown HER3.The expression of HER3 and p-HER3 were assessed by Western blot.Results Our in vitro results indicated a positive correlation between ROS production and p-HER3 protein express after irradiation(8Gy)in ECA-109 and KYSE-150 cell lines.HER3 knockdown significantly sensitized to radiation therapy,which was achieved by clonogenic survival assay and cell proliferation assay.We also found that loss of HER3 was associated with at least 1.51times enhanced(P<0.01)apoptosis,2.14 times higher(P<0.001)DNA double-strand breaks and 1.15 times higher(P<0.05)G2/M cell cycle arrest in cell lines after radiation.Meanwhile,we confirmed the results in vivo by conducting mice tumor xenograft experiments.HER3 knockdown tumors showed a significantly better(P<0.001)response to radiation therapy as compared to controlsConclusion ROS production could induce activation of HER3 after irradiation and knockdown HER3 in esophageal squamous cell carcinomas cells increased radiosensitivity.