title: Endoplasmic reticulum stress protects human thyroid carcinoma cell lines against ionizing radiation-induced apoptosis.
abstract: Radiotherapy is one of the most effective forms of cancer treatment, used in the treatment of a number of malignant tumors. However, the resistance of tumor cells to ionizing radiation remains a major therapeutic problem and the critical mechanisms determining radiation resistance are poorly defined. In the present study, a cellular endoplasmic reticulum (ER) stress microenvironment was established through the pretreatment of cultured thyroid cancer cells with tunicamycin (TM) and thapsigargin (TG), in order to mimic the ER stress response in a tumor microenvironment. This microenviroment was confirmed through the X‑box binding protein 1 splice process, glucose‑regulated protein 78 kD and ER degradation‑enhancing α‑mannosidase‑like mRNA expression. A clonogenic assay was used to measure cancer cell resistance to 60Co‑γ following TM pretreatment; in addition, human C/EBP homologous protein (CHOP) mRNA expression was determined and apoptosis assays were performed. The results showed that TM or TG pretreatment inhibited CHOP expression and reduced the apoptotic rate of cells. Furthermore, the results demonstrated that the induced ER stress response rendered cancer cells more resistant to ionizing radiation‑induced apoptosis. Therefore, the ER stress pathway may be a potential therapeutic target in order to improve the clinical efficiency of radiotherapy.
authors.affiliation: Department of Nuclear Medicine, Henan Provincial People's Hospital and People's Hospital of Zhengzhou University, Zhengzhou, Henan 450003, P.R. China.
authors.forename: Xin-Yu
authors.initials: XY
authors.lastname: Wu
authors.affiliation: Department of Radiation Oncology, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, Henan 450052, P.R. China.
authors.forename: Rui-Tai
authors.initials: RT
authors.lastname: Fan
authors.affiliation: Department of Nuclear Medicine, Henan Provincial People's Hospital and People's Hospital of Zhengzhou University, Zhengzhou, Henan 450003, P.R. China.
authors.forename: Xin-Hui
authors.initials: XH
authors.lastname: Yan
authors.affiliation: Department of Nuclear Medicine, Henan Provincial People's Hospital and People's Hospital of Zhengzhou University, Zhengzhou, Henan 450003, P.R. China.
authors.forename: Jing
authors.initials: J
authors.lastname: Cui
authors.affiliation: Department of Nuclear Medicine, Henan Provincial People's Hospital and People's Hospital of Zhengzhou University, Zhengzhou, Henan 450003, P.R. China.
authors.forename: Jun-Ling
authors.initials: JL
authors.lastname: Xu
authors.affiliation: Department of Radiation Oncology, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, Henan 450052, P.R. China.
authors.forename: Hao
authors.initials: H
authors.lastname: Gu
authors.affiliation: Department of Nuclear Medicine, Henan Provincial People's Hospital and People's Hospital of Zhengzhou University, Zhengzhou, Henan 450003, P.R. China.
authors.forename: Yong-Ju
authors.initials: YJ
authors.lastname: Gao
mesh_terms: D017209:Apoptosis / Q000528:radiation effects; D045744:Cell Line, Tumor; D059865:Endoplasmic Reticulum Stress / Q000528:radiation effects; D006801:Humans; D011836:Radiation Tolerance; D011839:Radiation, Ionizing; D013964:Thyroid Neoplasms / Q000378:metabolism / Q000532:radiotherapy*