title: Knockdown of Cathepsin L promotes radiosensitivity of glioma stem cells both in vivo and in vitro.
abstract: The presence of glioma stem cells (GSCs) in tumor is relevant for glioma treatment resistance. This study assessed whether knockdown of Cathepsin L can influence GSC growth, tumor radiosensitivity, and clinical outcome. Protein levels of Cathepsin L and stem cell markers (CD133 and Nestin) were analyzed in samples from 90 gliomas of different WHO grades and 6 normal brain tissues by immunohistochemistry. Two glioma stem cell lines with overexpressed Cathepsin L were stably transfected with Cathepsin L short hairpin RNA expression vectors. The effects of Cathepsin L inhibition on radiosensitivity, self-renewal, stemness, DNA damage, and apoptosis were evaluated. In addition, an intracranial animal model and subcutaneous tumor xenografts in nude mice were used to assess tumor response to Cathepsin L inhibition in vivo. Our results proved that expressions of Cathepsin L and CD133, but not of Nestin, correlated with malignant grades of glioma tissues. GSCs with high Cathepsin L and CD133 co-expression were extraordinarily radioresistant. Cathepsin L inhibition with radiotherapy significantly reduced GSC growth, promoted apoptosis, and improved radiosensitivity. Knockdown of Cathepsin L resulted in a dramatic reduction of CD133 expression, as well as the decreased phosphorylation of DNA repair checkpoint proteins (ATM and DNA-PKcs). Furthermore, combination of Cathepsin L inhibition and radiotherapy potently blocked tumor growth and decreased blood vessel formation in vivo. Taken together, these findings suggest Cathepsin L as a promising therapeutic target for clinical therapy in GBM patients.
authors.affiliation: Department of Pharmacology, College of Pharmaceutical Sciences, Soochow University, Suzhou, China.
authors.forename: Wenjuan
authors.initials: W
authors.lastname: Wang
authors.affiliation: Department of Pharmacology, College of Pharmaceutical Sciences, Soochow University, Suzhou, China.
authors.forename: Linmei
authors.initials: L
authors.lastname: Long
authors.affiliation: Department of Pharmacology, College of Pharmaceutical Sciences, Soochow University, Suzhou, China.
authors.forename: Long
authors.initials: L
authors.lastname: Wang
authors.affiliation: Department of Pharmacology, College of Pharmaceutical Sciences, Soochow University, Suzhou, China; Department of Pharmacy, Affiliated Hospital of Jiangsu University, Zhenjiang, China.
authors.forename: Caihong
authors.initials: C
authors.lastname: Tan
authors.affiliation: Department of Neurosurgery, Suzhou Kowloon Hospital of Shanghai Jiao Tong University School of Medicine, Suzhou, China.
authors.forename: Xifeng
authors.initials: X
authors.lastname: Fei
authors.affiliation: Department of Radiotherapy, the Second Affiliated Hospital of Soochow University, Suzhou, China.
authors.forename: Leisong
authors.initials: L
authors.lastname: Chen
authors.affiliation: Department of Neurosurgery, the Second Affiliated Hospital of Soochow University, Suzhou, China.
authors.forename: Qiang
authors.initials: Q
authors.lastname: Huang
authors.affiliation: Department of Pharmacology, College of Pharmaceutical Sciences, Soochow University, Suzhou, China. Electronic address: liangzhongqin@suda.edu.cn.
authors.forename: Zhongqin
authors.initials: Z
authors.lastname: Liang
mesh_terms: D000071916:AC133 Antigen; D000818:Animals; D015703:Antigens, CD / Q000378:metabolism; D017209:Apoptosis / Q000528:radiation effects; D064007:Ataxia Telangiectasia Mutated Proteins / Q000378:metabolism; D001932:Brain Neoplasms / Q000201:enzymology / Q000235:genetics / Q000473:pathology / Q000532:radiotherapy*; D056668:Cathepsin L / Q000235:genetics / Q000378:metabolism*; D045744:Cell Line, Tumor; D000066673:Cell Self Renewal / Q000528:radiation effects; D004249:DNA Damage; D051747:DNA-Activated Protein Kinase / Q000378:metabolism; D015536:Down-Regulation; D015971:Gene Expression Regulation, Enzymologic; D015972:Gene Expression Regulation, Neoplastic; D055785:Gene Knockdown Techniques; D005910:Glioma / Q000201:enzymology / Q000235:genetics / Q000473:pathology / Q000532:radiotherapy*; D006023:Glycoproteins / Q000378:metabolism; D006801:Humans; D008819:Mice, Nude; D060787:Neoplasm Grading; D014411:Neoplastic Stem Cells / Q000201:enzymology / Q000473:pathology / Q000528:radiation effects*; D009687:Nuclear Proteins / Q000378:metabolism; D010455:Peptides / Q000378:metabolism; D034622:RNA Interference; D011836:Radiation Tolerance; D013997:Time Factors; D014162:Transfection; D023041:Xenograft Model Antitumor Assays
chemical_list: D000071916:AC133 Antigen; D015703:Antigens, CD; D006023:Glycoproteins; D009687:Nuclear Proteins; C000606023:PROM1 protein, human; D010455:Peptides; C000606024:Prom1 protein, mouse; C576324:ATM protein, human; D064007:Ataxia Telangiectasia Mutated Proteins; D051747:DNA-Activated Protein Kinase; C497263:PRKDC protein, human; C534281:CTSL protein, human; D056668:Cathepsin L
keywords: Cathepsin L; Glioma stem cells; Radiosensitivity