Nuclear Factor-Kappa B Inhibition Can Enhance Apoptosis of Differentiated Thyroid Cancer Cells Induced by 131I

Abstract

ObjectiveTo evaluate changes of nuclear factor-kappa B (NF-κB) during radioiodine 131 (131I) therapy and whether NF-κB inhibition could enhance 131I-induced apoptosis in differentiated thyroid cancer (DTC) cells in a synergistic manner.MethodsThree 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.ResultsThe 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 131I, yet significant suppression was achieved by NF-κB inhibition. Western blot proved 131I 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 131I 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.ConclusionWe demonstrated that 131I could induce NF-κB activation, which would attenuate 131I 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.

Nuclear factor-kappa B inhibition can enhance therapeutic efficacy of 131I on the in vivo management of differentiated thyroid cancer

“…Our recent in vitro experiment revealed that 131 I could induce NF-κB activation, which attenuated 131 I induced apoptosis. NF-κB inhibition was effective in suppressing NF-κB regulated anti-apoptotic changes and in combined regimen apoptosis was achieved synergistically (Meng et al, 2012). This work also showed the NF-κB inhibition approach did not significantly influence iodine uptake of DTC cells.…”

“…The multi-well colorimetric assay for active NF-κB function was performed (Meng et al, 2008(Meng et al, , 2012Starenki et al, 2004a,b). Briefly, equal amounts of nuclear extracts were incubated in 96-well plates coated with immobilized oligonucleotide containing a NF-κB consensus binding site.…”

“…NF-κB expression was assessed by Western blot (Meng et al, 2008(Meng et al, , 2012Starenki et al, 2004a,b). Equal amounts of protein were electrophoresed by SDS-PAGE in 10% polyacrylamide gels, and then transferred onto nitrocellulose membrane (Amersham Biosciences, NJ, USA) by semidry blotting.…”

“…Another way to circumvent therapeutic resistance is to promote apoptosis. Nuclear factor-kappa B (NF-κB) has been demonstrated to play a crucial role in thyroid cancer development, chemotherapy resistance and radiotherapy resistance (Meng et al, 2008(Meng et al, , 2012Pacifico and Leonardi, 2010;Palona et al, 2006;Starenki et al, 2004a,b). Our recent in vitro experiment revealed that 131 I could induce NF-κB activation, which attenuated 131 I induced apoptosis.…”

NF‐κB inhibition reverses acidic bile‐induced miR‐21, miR‐155, miR‐192, miR‐34a, miR‐375 and miR‐451a deregulations in human hypopharyngeal cells

“…BAY 11‐7082 was selected as a reliable inhibitor of NF‐κB pathway that has been widely used in many studies exploring the effect of NF‐κB 11, 24, 25. It has been suggested that BAY 11‐7082 offers the most rapid and potent antitumour effect among other NF‐κB inhibitors 24 and can possibly be used as a sensitizer of anticancer therapy,26, 27 increasing the intrinsic susceptibility of cancer cells to chemotherapeutic agents 28…”