title: Calanquinone A induces anti-glioblastoma activity through glutathione-involved DNA damage and AMPK activation.
abstract: Glioblastoma, a highly malignant glioma, is resistant to both radiation and chemotherapy and is an intractable problem in clinical treatment. New therapeutic approaches are in urgent need. Calanquinone A, an herbal constituent, displayed anti-proliferative activity against glioblastoma cells, including A172, T98 and U87. Flow cytometric analysis showed an S phase arrest and a subsequent apoptosis to calanquinone A action. Further identification demonstrated a rapid increase of γH2A.X formation at S phase. The data together with comet tail formation and Chk1 activation indicated DNA damage response. N-acetyl cysteine (an antioxidant and a glutathione precursor) and exogenously applied glutathione, but not trolox (an antioxidant), completely abolished calanquinone A-induced effects. Immunofluorescence assay revealed that calanquinone A decreased the intracellular glutathione levels in both A172 and T98 cells. However, calanquinone A, by itself, did not conjugate glutathione. The data suggested that the decrease of cellular glutathione predominantly contributed to the anticancer mechanism. Furthermore, calanquinone A induced the activation of AMP-activated protein kinase (AMPK) and the inhibition of p70S6K activity. Rhodamine efflux assay showed that calanquinone A did not block efflux activity, indicating that calanquinone A was not a P-glycoprotein substrate. In summary, the data suggest that calanquinone A displays anti-glioblastoma activity through a decrease of cellular glutathione levels that subsequently induces DNA damage stress and AMPK activation, leading to cell cycle arrest at S-phase and apoptotic cell death. Furthermore, calanquinone A does not serve as a P-glycoprotein substrate, suggesting a potential for further development in anti-glioblastoma therapy.
authors.affiliation: School of Pharmacy, National Taiwan University, No. 1, Sect. 1, Jen-Ai Road, Taipei 100, Taiwan.
authors.forename: Fan-Lun
authors.initials: FL
authors.lastname: Liu
authors.affiliation: School of Pharmacy, National Taiwan University, No. 1, Sect. 1, Jen-Ai Road, Taipei 100, Taiwan.
authors.forename: Jui-Ling
authors.initials: JL
authors.lastname: Hsu
authors.affiliation: Department of Chemistry, National Changhua University of Education, 1 Ching-Der Road, Changhua 50058, Taiwan.
authors.forename: Yean-Jang
authors.initials: YJ
authors.lastname: Lee
authors.affiliation: Department of Chemistry, National Changhua University of Education, 1 Ching-Der Road, Changhua 50058, Taiwan.
authors.forename: Yu-Shun
authors.initials: YS
authors.lastname: Dong
authors.affiliation: School of Pharmacy, National Taiwan University, No. 1, Sect. 1, Jen-Ai Road, Taipei 100, Taiwan. Electronic address: flkung@ntu.edu.tw.
authors.forename: Fan-Lu
authors.initials: FL
authors.lastname: Kung
authors.affiliation: Division of Medicinal Chemistry, College of Pharmacy, The Ohio State University, Columbus, OH 43210, USA.
authors.forename: Ching-Shih
authors.initials: CS
authors.lastname: Chen
authors.affiliation: School of Pharmacy, National Taiwan University, No. 1, Sect. 1, Jen-Ai Road, Taipei 100, Taiwan. Electronic address: jhguh@ntu.edu.tw.
authors.forename: Jih-Hwa
authors.initials: JH
authors.lastname: Guh
mesh_terms: D055372:AMP-Activated Protein Kinases / Q000378:metabolism*; D000970:Antineoplastic Agents / Q000494:pharmacology*; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D004249:DNA Damage; D004789:Enzyme Activation / Q000187:drug effects; D005909:Glioblastoma / Q000473:pathology*; D005978:Glutathione / Q000378:metabolism*; D006801:Humans; D042541:Intracellular Space / Q000187:drug effects / Q000378:metabolism; D011809:Quinones / Q000494:pharmacology*; D038762:Ribosomal Protein S6 Kinases, 70-kDa / Q000378:metabolism; D059807:S Phase Cell Cycle Checkpoints / Q000187:drug effects
chemical_list: D000970:Antineoplastic Agents; D011809:Quinones; C530567:calanquinone A; D038762:Ribosomal Protein S6 Kinases, 70-kDa; D055372:AMP-Activated Protein Kinases; D005978:Glutathione
keywords: AMPK; Calanquinone A; DNA damage; Glioblastoma; Glutathione