title: Piperlongumine induces cell death through ROS-mediated CHOP activation and potentiates TRAIL-induced cell death in breast cancer cells.
abstract: OBJECTIVE
  Piperlongumine (PL) has been shown to selectively induce apoptotic cell death in cancer cells via reactive oxygen species (ROS) accumulation. In this study, we characterized a molecular mechanism for PL-induced cell death.
  
  
  METHODS
  Cell viability and cell death were assessed by MTT assay and Annexin V-FITC/PI staining, respectively. ROS generation was measured using the H2DCFDA. Small interfering RNA (siRNA) was used for suppressing gene expression. The mRNA and protein expression were analyzed by RT-PCR and Western blot analysis, respectively.
  
  
  RESULTS
  We found that PL promotes C/EBP homologous protein (CHOP) induction, which leads to the up-regulation of its targets Bim and DR5. Pretreatment with the ROS scavenger N-acetyl-cysteine abolishes the PL-induced up-regulation of CHOP and its target genes, suggesting an essential role for ROS in PL-induced CHOP activation. The down-regulation of CHOP or Bim with siRNA efficiently attenuates PL-induced cell death, suggesting a critical role for CHOP in this cell death. Furthermore, PL potentiates TRAIL-induced cytotoxicity in breast cancer cells by upregulating DR5, as DR5 knockdown abolished the sensitizing effect of PL on TRAIL responses.
  
  
  CONCLUSIONS
  Overall, our data suggest a new mechanism for the PL-induced cell death in which ROS mediates CHOP activation, and combination treatment with PL and TRAIL could be a potential strategy for breast cancer therapy.
authors.affiliation: KIRAMS Radiation Biobank, Korea Institute of Radiological and Medical Sciences, 75 Nowon-ro, Nowon-gu, Seoul, 139-709, Republic of Korea.
authors.forename: Hyeon-Ok
authors.initials: HO
authors.lastname: Jin
authors.forename: Yun-Han
authors.initials: YH
authors.lastname: Lee
authors.forename: Jin-Ah
authors.initials: JA
authors.lastname: Park
authors.forename: Ha-Na
authors.initials: HN
authors.lastname: Lee
authors.forename: Jin-Hee
authors.initials: JH
authors.lastname: Kim
authors.forename: Ji-Young
authors.initials: JY
authors.lastname: Kim
authors.forename: BoRa
authors.initials: B
authors.lastname: Kim
authors.forename: Sung-Eun
authors.initials: SE
authors.lastname: Hong
authors.forename: Hyun-Ah
authors.initials: HA
authors.lastname: Kim
authors.forename: Eun-Kyu
authors.initials: EK
authors.lastname: Kim
authors.forename: Woo Chul
authors.initials: WC
authors.lastname: Noh
authors.forename: Jong-Il
authors.initials: JI
authors.lastname: Kim
authors.forename: Yoon Hwan
authors.initials: YH
authors.lastname: Chang
authors.forename: Seok-Il
authors.initials: SI
authors.lastname: Hong
authors.forename: Young-Jun
authors.initials: YJ
authors.lastname: Hong
authors.forename: In-Chul
authors.initials: IC
authors.lastname: Park
authors.forename: Jin Kyung
authors.initials: JK
authors.lastname: Lee
mesh_terms: D017209:Apoptosis / Q000187:drug effects*; D051017:Apoptosis Regulatory Proteins / Q000502:physiology; D000072224:Bcl-2-Like Protein 11; D001943:Breast Neoplasms / Q000188:drug therapy* / Q000473:pathology; D045744:Cell Line, Tumor; D004148:Dioxolanes / Q000494:pharmacology*; D005260:Female; D006801:Humans; D008565:Membrane Proteins / Q000502:physiology; D011518:Proto-Oncogene Proteins / Q000502:physiology; D017382:Reactive Oxygen Species / Q000378:metabolism*; D053220:Receptors, TNF-Related Apoptosis-Inducing Ligand / Q000502:physiology; D053221:TNF-Related Apoptosis-Inducing Ligand / Q000494:pharmacology*; D051742:Transcription Factor CHOP / Q000378:metabolism*; D010881:Piperidones
chemical_list: D051017:Apoptosis Regulatory Proteins; D000072224:Bcl-2-Like Protein 11; D004148:Dioxolanes; D008565:Membrane Proteins; D011518:Proto-Oncogene Proteins; D017382:Reactive Oxygen Species; D053220:Receptors, TNF-Related Apoptosis-Inducing Ligand; D053221:TNF-Related Apoptosis-Inducing Ligand; D051742:Transcription Factor CHOP; C000606775:BCL2L11 protein, human; C497249:DDIT3 protein, human; C498077:piperlongumine; D010881:Piperidones