title: Inhibition of nuclear factor-κB activity enhanced chemosensitivity to cisplatin in human lung adeno-carcinoma A549 cells under chemical hypoxia conditions.
abstract: BACKGROUND
  Tumor hypoxia, one of the features of solid tumors, is associated with chemo-resistance. Recently, nuclear factor-κB (NF-κB) was found to be activated during hypoxia. However, the impact of NF-κB activation on chemo-resistance during hypoxia remains unknown.
  
  
  METHODS
  Human lung adenocarcinoma A549 cells were transfected with NF-κB p65siRNA and treated with cobalt chloride (CoCl2) to mimic hypoxia in the presence or absence of cisplatin. NF-κB expression was measured by Western blotting, immune-fluorescence and real-time PCR. Hypoxia-inducible factor-1α (HIF-1α) and Bcl-2 expression were determined by Western blotting. Cell apoptosis and survival with half-maximum inhibitory concentration (IC50) of cisplatin were determined by Annexin V-FITC/PI and 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide (MTT), respectively.
  
  
  RESULTS
  Exposure of A549 cells to CoCl2 increased nuclear HIF-1a protein expression, and enhanced NF-κB p65 protein nuclear accumulation (the mark of NF-κB activation) in a time and dose dependant manner. CoCl2 did not promote apoptosis in A549 cells; on the contrary, it reduced cisplatin-induced apoptosis and increased the IC50 of cisplatin. However, when we inhibited CoCl2-induced activation of NF-κB through NF-κB p65siRNA, cisplatin-induced apoptosis was increased and IC50 of cisplatin was reduced to levels similar to those in control cells. Meanwhile, CoCl2-induced Bcl-2 overexpression was down-regulated in the presence of cisplatin when NF-κB activity was inhibited.
  
  
  CONCLUSIONS
  Up-regulating Bcl-2 might be involved in NF-κB activation induced resistance to cisplatin in A549 cells under CoCl2-induced chemical hypoxia.
authors.affiliation: Department of Respiratory Diseases, Xiangya Hospital, Central South University, Changsha, Hunan 410007, China.
authors.forename: Fang
authors.initials: F
authors.lastname: Li
authors.forename: Li
authors.initials: L
authors.lastname: Huang
authors.forename: Xiao-Li
authors.initials: XL
authors.lastname: Su
authors.forename: Qi-Hua
authors.initials: QH
authors.lastname: Gu
authors.forename: Cheng-Ping
authors.initials: CP
authors.lastname: Hu
mesh_terms: D000230:Adenocarcinoma / Q000378:metabolism*; D000077192:Adenocarcinoma of Lung; D017209:Apoptosis / Q000187:drug effects; D045744:Cell Line, Tumor; D002470:Cell Survival / Q000187:drug effects; D002945:Cisplatin / Q000494:pharmacology*; D006801:Humans; D000860:Hypoxia / Q000503:physiopathology*; D008175:Lung Neoplasms / Q000378:metabolism*; D016328:NF-kappa B / Q000378:metabolism*; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000378:metabolism
chemical_list: D016328:NF-kappa B; D019253:Proto-Oncogene Proteins c-bcl-2; D002945:Cisplatin