title: Chloride intracellular channel 1 identified using proteomic analysis plays an important role in the radiosensitivity of HEp-2 cells via reactive oxygen species production.
abstract: The nature of the molecules underlying the radioresistance phenotype of laryngeal cancer cells remains to be established. We initially generated radioresistant laryngeal cancer cell lines from human HEp-2 cells with fractionated radiation. These RR-HEp-2 cells and isolated clones displayed more radioresistant and anti-apoptotic phenotypes than parental HEp-2 cells after radiation. Characteristics of RR-Hep-2 cell lines were confirmed by upregulation of radioresistance-related genes, such as epidermal growth factor receptor, Hsp90, and Bcl-xl. Subsequently, we examined proteome changes between HEp-2 and RR-HEp-2 cells and identified 16 proteins showing significantly altered expression levels. Interestingly, protein expression of chloride intracellular channel 1 (CLIC1) was markedly suppressed in RR-HEp-2 cells, compared with non-irradiated control cells. Suppression of CLIC1 with an indanyloxyacetic acid-94 or small interfering RNA led to radioresistance in HEp-2 cells by suppressing the radiation-induced cellular ROS level. However, ectopic overexpression of CLIC1 induced radiosensitivity in RR-HEp-2 cells via induction of ROS level after radiation, suggesting that the protein acts as a positive regulator of ROS production. Our results collectively indicate that suppression of CLIC1 contributes to acquisition of the radioresistance phenotype of laryngeal cancer cells via inhibition of ROS production, implying that this protein is an important candidate molecule for radiotherapy in radioresistant laryngeal cancer cells.
authors.affiliation: Division of Radiation Cancer Research, Korea Institute of Radiological and Medical Sciences, Seoul, Korea.
authors.forename: Jae-Sung
authors.initials: JS
authors.lastname: Kim
authors.forename: Jong Wook
authors.initials: JW
authors.lastname: Chang
authors.forename: Hong Shik
authors.initials: HS
authors.lastname: Yun
authors.forename: Kyung Mi
authors.initials: KM
authors.lastname: Yang
authors.forename: Eun-Hee
authors.initials: EH
authors.lastname: Hong
authors.forename: Dong Hyun
authors.initials: DH
authors.lastname: Kim
authors.forename: Hong-Duck
authors.initials: HD
authors.lastname: Um
authors.forename: Kee-Ho
authors.initials: KH
authors.lastname: Lee
authors.forename: Su-Jae
authors.initials: SJ
authors.lastname: Lee
authors.forename: Sang-Gu
authors.initials: SG
authors.lastname: Hwang
mesh_terms: D016923:Cell Death / Q000528:radiation effects; D045744:Cell Line, Tumor; D018118:Chloride Channels / Q000037:antagonists & inhibitors / Q000378:metabolism*; D006801:Humans; D009363:Neoplasm Proteins / Q000378:metabolism; D040901:Proteomics / Q000379:methods*; D011836:Radiation Tolerance / Q000528:radiation effects; D011839:Radiation, Ionizing; D017382:Reactive Oxygen Species / Q000378:metabolism*; D015203:Reproducibility of Results
chemical_list: C501966:CLIC1 protein, human; D018118:Chloride Channels; D009363:Neoplasm Proteins; D017382:Reactive Oxygen Species