Increased apoptosis of A549 cells by overexpression of helicase-like transcription factor induced by radiation exposure

Abstract

Objective To study the effects of overexpression of helicase-like transcription factor (HLTF) on radiation-induced apoptosis of human lung carcinoma cells.Methods Human lung carcinoma cellline A549 were cultured,transfected with FLAG-tagged HLTF expression plasmid pcDNA3.1/HLTF-FLAG (HLTF gene transfection group) ,empty plasmid vector pcDNA3.1 (empty vector group) ,and mock transfection group,respectively,and then exposed to 60Co γ-ray irradiation.Cell apoptosis was observed by flow cytometry 48 h post-irradiation.Western blotting was used to detect the levels of HLTF in the nucleus and cytoplasm and the release of cytochrome C from mitochondria into cytoplasm.Results The apoptosis rate of the HLTF gene group was (32.2 ± 2.1) %,significantly higher than those of the empty vector group [(11.4±2.3)%] and mock transfection group [(11.1 ±1.8)%] (F=101.85,P＜0.05).The level of cytochrome C in the cytoplasm of the HLTF gene group was significantly higher than that of the empty plasmid group.Conclusions HLTF protein sensitizes human lung carcinoma cells to radiation-induced apoptosis,partly by promoting the nuclear-cytoplasma transition of HLTF protein and the increased release of cytochrome C. Key words: Cell apoptosis; Helicase-like transcription factor (HLTF); Cytochrome C