Autophagy Inhibition Promotes Gambogic Acid-induced Suppression of Growth and Apoptosis in Glioblastoma Cells

  • Luo, Guo-Xuan (Department of Neurosurgery, Guangdong NO.2 Provincial People's Hospital) ;
  • Cai, Jun (Department of Neurosurgery, Guangdong Provincial Hospital of Traditional Chinese Medicine) ;
  • Lin, Jing-Zhi (Department of Neurosurgery, Guangdong NO.2 Provincial People's Hospital) ;
  • Luo, Wei-Shi (Department of Neurosurgery, Guangdong NO.2 Provincial People's Hospital) ;
  • Luo, Heng-Shan (Department of Neurosurgery, Ningxiang County People's Hospital) ;
  • Jiang, Yu-Yang (The Key Laboratory of Chemical Biology, Guangdong Province, Graduate School at Shenzhen, Tsinghua University) ;
  • Zhang, Yong (Department of Neurosurgery, Guangdong NO.2 Provincial People's Hospital)
  • Published : 2012.12.31


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. Conclusion: 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.


Gambogic acid;glioblastoma multiforme;apoptosis;autophagy


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