%0 Journal Article
%T Nuclear Factor-Kappa B Inhibition Can Enhance Apoptosis of Differentiated Thyroid Cancer Cells Induced by 131I
%A Zhaowei Meng
%A Shanshan Lou
%A Jian Tan
%A Ke Xu
%A Qiang Jia
%A Wei Zheng
%J PLOS ONE
%D 2012
%I Public Library of Science (PLoS)
%R 10.1371/journal.pone.0033597
%X Objective To evaluate changes of nuclear factor-kappa B (NF-百B) during radioiodine 131 (131I) therapy and whether NF-百B inhibition could enhance 131I-induced apoptosis in differentiated thyroid cancer (DTC) cells in a synergistic manner. Methods Three human DTC cell lines were used. NF-百B inhibition was achieved by using a NF-百B 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-百B. Then NF-百B 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-百B 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-百B function and reporter gene activities due to 131I, yet significant suppression was achieved by NF-百B inhibition. Western blot proved 131I could increase nuclear NF-百B concentration, while NF-百B inhibition reduced NF-百B concentration. Western blot also demonstrated significant up-regulation of XIAP, cIAP1, and Bcl-xL after 131I therapy. And inhibition of NF-百B 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-百B was inhibited. Conclusion We demonstrated that 131I could induce NF-百B activation, which would attenuate 131I efficacy in DTC cells. NF-百B inhibition by Bay 11-7082 or by p65 siRNA transfection was effective in suppressing NF-百B regulated anti-apoptotic changes and in combined regimen apoptosis was achieved synergistically.
%U http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0033597