title: Andrographolide induces cell cycle arrest at G2/M phase and cell death in HepG2 cells via alteration of reactive oxygen species.
abstract: The cytotoxicity of andrographolide to HepG2 human hepatoma cells was investigated in the present study. Growth of HepG2 cells was affected in the presence of andrographolide with an IC(50) of 40.2 microM after 48 h treatment. Flow cytometric analysis and DNA fragmentation assay revealed that andrographolide induced cell cycle arrest at G2/M phase and a late apoptosis of the cells. The occurrence of cell cycle arrest was accompanied by the collapse of mitochondrial membrane potential (MMP) and an intracellular increase of hydrogen peroxide (H(2)O(2)) but a decrease of superoxide radicals (O(2)(-)) and reduced glutathione. In the treated cells, expression of Bax as well as the transcriptional controller of this pro-apoptotic gene, p53, was upregulated but not other apoptotic proteins such as Bad, Bcl-2 and Bcl-X(L). Although the activity of caspase-3, which has direct effect on apoptosis, was also enhanced by the presence of andrographolide, cell death of HepG2 could neither be prevented by a specific inhibitor of capsase-3 nor the pan-caspase inhibitor-zVAD (Val-Ala-Asp), indicating that it was a caspase-independent cell death. Since the overall percentage of apoptotic cells was relatively small throughout the experimental studies, we conclude that the cytotoxic effect of andrographolide on HepG2 cells is primary attributed to the induction of cell cycle arrest via the alteration of cellular redox status.
authors.affiliation: Research Group for Bioactive Products, Department of Biology and Chemistry, City University of Hong Kong, 83 Tat Chee Ave., Kowloon, Hong Kong SAR, China.
authors.forename: Jieliang
authors.initials: J
authors.lastname: Li
authors.forename: Hon-Yeung
authors.initials: HY
authors.lastname: Cheung
authors.forename: Zhiqiang
authors.initials: Z
authors.lastname: Zhang
authors.forename: Gallant K L
authors.initials: GK
authors.lastname: Chan
authors.forename: Wang-Fun
authors.initials: WF
authors.lastname: Fong
mesh_terms: D000970:Antineoplastic Agents / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects*; D016203:CDC2 Protein Kinase / Q000378:metabolism; D053148:Caspase 3 / Q000378:metabolism; D002455:Cell Division / Q000187:drug effects*; D045744:Cell Line, Tumor; D002470:Cell Survival / Q000187:drug effects; D053938:DNA Fragmentation; D004224:Diterpenes / Q000494:pharmacology*; D016195:G2 Phase / Q000187:drug effects*; D005978:Glutathione / Q000378:metabolism; D006801:Humans; D006861:Hydrogen Peroxide / Q000378:metabolism; D053078:Membrane Potential, Mitochondrial / Q000187:drug effects; D016328:NF-kappa B / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000378:metabolism; D013481:Superoxides / Q000378:metabolism; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism
chemical_list: D000970:Antineoplastic Agents; D004224:Diterpenes; D016328:NF-kappa B; D017382:Reactive Oxygen Species; D016159:Tumor Suppressor Protein p53; D013481:Superoxides; C030419:andrographolide; D006861:Hydrogen Peroxide; D016203:CDC2 Protein Kinase; D053148:Caspase 3; D005978:Glutathione