title: Differential response of human glioblastoma cell lines to combined camptothecin and ionizing radiation treatment.
abstract: In order to enhance the cytotoxicity of radiation, camptothecin (CPT), an inhibitor of DNA topoisomerase I, was added to the cultured glioma cell lines before irradiation (IR). Radiation responses of five glioblastoma cell lines (U87-MG, U373-MG, GHE, GaMG and SNB-19) treated with CPT were analyzed in terms of cell and colony counts, cell cycle progression, expression of histone gamma H2AX, DNA repair protein Rad50, survivin, cleaved caspase 3, p53 and of topoisomerase I. CPT enhanced the radiotoxicity in U87-MG and SNB-19 cell lines if cell and colony counts were used as the end-points. In contrast, pre-treatment with CPT of U373-MG, GHE and GaMG cell lines did not enhance cytotoxicity of IR in terms of cell and colony counts but accelerated DNA damage repair assessed by Rad50 foci. CPT treated glioma cells revealed at least two subpopulations with respect to the expression of histone gamma H2AX, a marker of DNA double-strand breaks. The cell lines tested also differed in the expression of survivin, cleaved caspase 3, p53 and of topoisomerase I. The failure of CPT to enhance the radiotoxicity of glioma U373-MG, GHE and GaMG cell lines in terms of cell and colony counts was found to correlate with accelerated DNA damage repair, and with low expression of topoisomerase I, a target of CPT.
authors: Klinik für Strahlentherapie der Universität Würzburg, Würzburg, Germany. djuzenova_t@klinik.uni-wuerzburg.de
authors: Cholpon S
authors: CS
authors: Djuzenova
authors: Teresa
authors: T
authors: Güttler
authors: Sabrina
authors: S
authors: Berger
authors: Astrid
authors: A
authors: Katzer
authors: Michael
authors: M
authors: Flentje
mesh_terms: D002166:Camptothecin / Q000627:therapeutic use*; D002455:Cell Division / Q000187:drug effects / Q000528:radiation effects; D002460:Cell Line; D045744:Cell Line, Tumor; D002470:Cell Survival / Q000187:drug effects / Q000528:radiation effects; D003131:Combined Modality Therapy; D005909:Glioblastoma / Q000188:drug therapy* / Q000532:radiotherapy*; D006801:Humans; D016896:Treatment Outcome
chemical_list: D002166:Camptothecin