title: Autophagy inhibition promotes gambogic acid-induced suppression of growth and apoptosis in glioblastoma cells.
abstract: OBJECTIVE
  To investigate the effects of gambogic acid (GA) on the growth of human malignant glioma cells.
  
  
  METHODS
  U251MG and U87MG human glioma cell lines were treated with GA and growth and proliferation were investigated by MTT and colony formation assays. Cell apoptosis was analyzed by annexin V FITC/PI flow cytometry, mitochondrial membrane potential assays and DAPI nuclear staining. Monodansylcadaverine (MDC) staining and GFP-LC3 localisation were used to detect autophagy. Western blotting was used to investigate the molecular changes that occurred in the course of GA treatment.
  
  
  RESULTS
  GA treatment significantly suppressed cell proliferation and colony formation, induced apoptosis in U251 and U87MG glioblastoma cells in a time- and dose-dependent manner. GA treatment also lead to the accumulation of monodansylcadaverine (MDC) in autophagic vacuoles, upregulated expressions of Atg5, Beclin 1 and LC3-II, and the increase of punctate fluorescent signals in glioblastoma cells pre-transfected with GFP-tagged LC3 plasmid. After the combination treatment of autophagy inhitors and GA, GA mediated growth inhibition and apoptotic cell death was further potentiated.
  
  
  CONCLUSIONS
  Our results suggested that autophagic responses play roles as a self-protective mechanism in GA-treated glioblastoma cells, and autophagy inhibition could be a novel adjunctive strategy for enhancing chemotherapeutic effect of GA as an anti-malignant glioma agent.
authors: Department of Neurosurgery, Guangdong NO.2 Provincial People's Hospital, Guangzhou, China. zhangyong0131@yahoo.com.cn
authors: Guo-Xuan
authors: GX
authors: Luo
authors: Jun
authors: J
authors: Cai
authors: Jing-Zhi
authors: JZ
authors: Lin
authors: Wei-Shi
authors: WS
authors: Luo
authors: Heng-Shan
authors: HS
authors: Luo
authors: Yu-Yang
authors: YY
authors: Jiang
authors: Yong
authors: Y
authors: Zhang
mesh_terms: D017209:Apoptosis / Q000187:drug effects; D001343:Autophagy / Q000187:drug effects; D045744:Cell Line, Tumor; D005909:Glioblastoma; D005910:Glioma; D006801:Humans