Cathepsin L suppression increases the radiosensitivity of human glioma U251 cells via G2/M cell cycle arrest and DNA damage

• Published in: Acta pharmacologica Sinica 2015-09, Vol.36 (9), p.1113-1125
• Main Authors: Zhang, Qing-qing, Wang, Wen-juan, Li, Jun, Yang, Neng, Chen, Gang, Wang, Zhong, Liang, Zhong-qin
• Format: Article
• Language: English
• Subjects: Apoptosis - radiation effects; Biomedical and Life Sciences; Biomedicine; Brain Neoplasms - genetics; Brain Neoplasms - metabolism; Brain Neoplasms - pathology; Brain Neoplasms - radiotherapy; Cathepsin L - analysis; Cathepsin L - antagonists & inhibitors; Cathepsin L - genetics; Cathepsin L - metabolism; Cell Line, Tumor; DNA Damage - radiation effects; DNA损伤; Enzyme Inhibitors - pharmacology; G2 Phase Cell Cycle Checkpoints - radiation effects; Glioma - genetics; Glioma - metabolism; Glioma - pathology; Glioma - radiotherapy; Humans; Immunology; Internal Medicine; Medical Microbiology; Original; original-article; Pharmacology/Toxicology; Radiation Tolerance; RNA Interference; RNA, Small Interfering - genetics; U251细胞; Vaccine; 放射敏感性; 突变型p53基因; 组织蛋白酶; 细胞周期阻滞; 脑胶质瘤; 辐射敏感性
• ISSN: 1671-4083; 1745-7254
• DOI: 10.1038/aps.2015.36

Aim： Cathepsin L is a lysosomal cysteine protease that plays important roles in cancer tumorigenesis, proliferation and chemotherapy resistance. The aim of this study was to determine how cathepsin L regulated the radiosensitivity of human glioma cells in vitro. Methods： Human glioma U251 cells （harboring the mutant type p53 gene） and U87 cells （harboring the wide type p53 gene） were irradiated with X-rays. The expression of cathepsin L was analyzed using Western blot and immunofluorescence assays. Cell survival and DNA damage were evaluated using clonogenic and comet assays, respectively. Flow cytometry was used to detect the cell cycle distribution. Apoptotic cells were observed using Hoechst 33258 staining and fluorescence microscopy. Results： Irradiation significantly increased the cytoplasmic and nuclear levels of cathepsin L in U251 cells but not in U87 cells. Treatment with the specific cathepsin L inhibitor Z-FY-CHO （10 pmol/L） or transfection with cathepsin L shRNA significantly increased the radiosensitivity of U251 cells. Both suppression and knockdown of cathepsin L in U251 cells increased irradiation-induced DNA damage and G2/M phase cell cycle arrest. Both suppression and knockdown of cathepsin L in U251 cells also increased irradiation- induced apoptosis, as shown by the increased levels of Bax and decreased levels of Bcl-2. Conclusion： Cathepsin L is involved in modulation of radiosensitivity in human glioma U251 cells （harboring the mutant type p53 gene） in vitro.