title: Nuclear factor-kappa B inhibition can enhance apoptosis of differentiated thyroid cancer cells induced by 131I.
abstract: OBJECTIVE
  To evaluate changes of nuclear factor-kappa B (NF-κB) during radioiodine 131 ((131)I) therapy and whether NF-κB inhibition could enhance (131)I-induced apoptosis in differentiated thyroid cancer (DTC) cells in a synergistic manner.
  
  
  METHODS
  Three human DTC cell lines were used. NF-κB inhibition was achieved by using a NF-κB inhibitor (Bay 11-7082) or by p65 siRNA transfection. Methyl-thiazolyl-tetrazolium assay was performed for cell viability assessment. DNA-binding assay, luciferase reporter assay, and Western blot were adopted to determine function and expression changes of NF-κB. Then NF-κB regulated anti-apoptotic factors XIAP, cIAP1, and Bcl-xL were measured. Apoptosis was analyzed by Western blot for caspase 3 and PARP, and by flow cytometry as well. An iodide uptake assay was performed to determine whether NF-κB inhibition could influence radioactive iodide uptake.
  
  
  RESULTS
  The methyl-thiazolyl-tetrazolium assay showed significant decrease of viable cells by combination therapy than by mono-therapies. The DNA-binding assay and luciferase reporter assay showed enhanced NF-κB function and reporter gene activities due to (131)I, yet significant suppression was achieved by NF-κB inhibition. Western blot proved (131)I could increase nuclear NF-κB concentration, while NF-κB inhibition reduced NF-κB concentration. Western blot also demonstrated significant up-regulation of XIAP, cIAP1, and Bcl-xL after (131)I therapy. And inhibition of NF-κB could significantly down-regulate these factors. Finally, synergism induced by combined therapy was displayed by significant enhancements of cleaved caspase 3 and PARP from Western blot, and of Annexin V positively staining from flow cytometry. The iodine uptake assay did not show significant changes when NF-κB was inhibited.
  
  
  CONCLUSIONS
  We demonstrated that (131)I could induce NF-κB activation, which would attenuate (131)I efficacy in DTC cells. NF-κB inhibition by Bay 11-7082 or by p65 siRNA transfection was effective in suppressing NF-κB regulated anti-apoptotic changes and in combined regimen apoptosis was achieved synergistically.
authors.affiliation: Department of Nuclear Medicine, Tianjin Medical University General Hospital, Tianjin, People's Republic of China. james_mencius@hotmail.com
authors.forename: Zhaowei
authors.initials: Z
authors.lastname: Meng
authors.forename: Shanshan
authors.initials: S
authors.lastname: Lou
authors.forename: Jian
authors.initials: J
authors.lastname: Tan
authors.forename: Ke
authors.initials: K
authors.lastname: Xu
authors.forename: Qiang
authors.initials: Q
authors.lastname: Jia
authors.forename: Wei
authors.initials: W
authors.lastname: Zheng
mesh_terms: D017209:Apoptosis / Q000187:drug effects* / Q000528:radiation effects*; D001483:Base Sequence; D002454:Cell Differentiation / Q000528:radiation effects; D045744:Cell Line, Tumor; D003131:Combined Modality Therapy; D006801:Humans; D051034:Inhibitor of Apoptosis Proteins / Q000378:metabolism; D007457:Iodine Radioisotopes / Q000627:therapeutic use*; D016328:NF-kappa B / Q000037:antagonists & inhibitors*; D009570:Nitriles / Q000494:pharmacology; D034741:RNA, Small Interfering / Q000235:genetics; D013450:Sulfones / Q000494:pharmacology; D013964:Thyroid Neoplasms / Q000188:drug therapy* / Q000378:metabolism / Q000532:radiotherapy*; D051996:Transcription Factor RelA / Q000037:antagonists & inhibitors / Q000235:genetics; D014162:Transfection; D051636:X-Linked Inhibitor of Apoptosis Protein / Q000378:metabolism; D051020:bcl-X Protein / Q000378:metabolism
chemical_list: C434003:3-(4-methylphenylsulfonyl)-2-propenenitrile; C494811:BCL2L1 protein, human; D051034:Inhibitor of Apoptosis Proteins; D007457:Iodine Radioisotopes; D016328:NF-kappa B; D009570:Nitriles; C498143:RELA protein, human; D034741:RNA, Small Interfering; D013450:Sulfones; D051996:Transcription Factor RelA; D051636:X-Linked Inhibitor of Apoptosis Protein; C496866:XIAP protein, human; D051020:bcl-X Protein