The dominant negative mutant Artemis enhances tumor cell radiosensitivity

Abstract

BackgroundTumor radioresistance often leads to treatment failure during radiotherapy. New strategies like developing radiosensitizer are clinically important. Intervention with DNA double-strand break repair is an effective way to modulate tumor cell radiosensitivity. This study focused on the mutant Artemis fragment-enhanced radiosensitivity of human cervical cancer cells. Material and methodsWe constructed two pEGFP-C1-based eukaryotic expression vectors encoding full-length and the mutant Artemis fragment (D37N-413aa), respectively. HeLa cells were stably transfected with these plasmids or vector. Cell survival was measured by the clonogenic assay. The γH2AX foci assay was used to monitor DNA repair after irradiation. Co-immunoprecipitation and Western blot analysis were performed to study protein interaction and phosphorylation of Artemis. ResultsExpression of the mutant Artemis fragment (D37N-413aa) delayed DNA DSB rejoining after irradiation, thereby enhanced radiosensitivity of HeLa cell. Further experiments indicate that this mutant Artemis fragment bind to DNA-PKcs and ATM, inhibited phosphorylation of endogenous Artemis, the key molecule for DNA repair and cell radiosensitivity. ConclusionsThe dominant negative mutant Artemis fragment (D37N-413aa) enhanced tumor cell radiosensitivity through blocking activity of endogenous Artemis and DNA repair. It is the first time to modulate tumor cell radiosensitivity via targeting Artemis. This novel mechanism of radiosensitivity strongly suggests the potential role of Artemis in cancer therapy.