title: [Small interfering RNA-mediated Nrf2 gene knockdown enhances hirsutanols A-induced cytotoxicity in cancer cells].
abstract: OBJECTIVE
  To investigate the effect of Nrf2 gene knockdown on hirsutanols A-induced cytotoxicity in cancer cells.
  
  
  METHODS
  The changes in the cell viability following treatment with different concentrations of hirsutanols A was detected by MTT assay, and the generation of reactive oxygen species (ROS) was assayed using flow cytometry. AnnexinV-FITC apoptosis kit was used to detect the cell apoptosis. Nrf2 protein expression in HepG2 and SW480 cells transfected with the siRNA targeting Nrf2 was analyzed with Western blotting.
  
  
  RESULTS
  At the concentrations of 1.25, 2.5, 5, 10, 20 and 40 µmol/L, hirsutanols A obviously inhibited the cell proliferation of human liver cancer HepG2 and colon cancer SW480 cells in a concentration-dependent manner. The levels of hydrogen peroxide increased rapidly after hirsutanols A treatment in both HepG2 (30 µmol/L) and SW480 (15 µmol/L) cells. Hirsutanols A also induced apoptosis of the two cells. Pretreatment with 5 mmol/L NAC totally inhibited apoptosis and ROS accumulation in the two cells induced by hirsutanols A. Transfection of HepG2 and SW480 cells with the siRNA caused a significant reduction in Nrf2 protein expression, which resulted in an increased sensitivity of the cells to hirsutanols A.
  
  
  CONCLUSIONS
  Hirsutanols A can induce apoptosis in HepG2 and SW480 cells by promoting ROS production and up-regulating Nrf2 expression. Nrf2 knockdown by siRNA can increase the sensitivity of the cancer cells to hirsutanols A in vitro.
authors.affiliation: State Key Laboratory of Oncology in South China, Cancer Center, Sun Yat-sen University, Guangzhou, China. promjg@163.com
authors.forename: Jianguo
authors.initials: J
authors.lastname: Ma
authors.forename: Houjin
authors.initials: H
authors.lastname: Li
authors.forename: Rong
authors.initials: R
authors.lastname: Deng
authors.forename: Gongkan
authors.initials: G
authors.lastname: Feng
authors.forename: Xiaofeng
authors.initials: X
authors.lastname: Zhu
mesh_terms: D017209:Apoptosis / Q000187:drug effects; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects*; D003110:Colonic Neoplasms / Q000378:metabolism / Q000473:pathology; D015972:Gene Expression Regulation, Neoplastic; D055785:Gene Knockdown Techniques; D006801:Humans; D008113:Liver Neoplasms / Q000378:metabolism / Q000473:pathology; D051267:NF-E2-Related Factor 2 / Q000235:genetics*; D034741:RNA, Small Interfering; D017382:Reactive Oxygen Species / Q000378:metabolism; D012717:Sesquiterpenes / Q000494:pharmacology*
chemical_list: D051267:NF-E2-Related Factor 2; C495635:NFE2L2 protein, human; D034741:RNA, Small Interfering; D017382:Reactive Oxygen Species; D012717:Sesquiterpenes; C569055:hirsutanol A