Effects of nuclear factor‑κB on the uptake of 131iodine and apoptosis of thyroid carcinoma cells

Abstract

Thyroid carcinoma is primarily treated by surgery combined with radioactive 131iodine (131I) treatment; however, certain patients exhibit resistance to 131I treatment. Previous research indicated that nuclear factor‑κB (NF‑κB) was associated with resistance to 131I in cancer cells. The present study aimed to investigate the effects of NF‑κB on 131I uptake and apoptosis in thyroid carcinoma cells. TPC‑1 and BCPAP cell lines were employed as research models in the present study, and the expression of NF‑κB was inhibited by RNA interference (RNAi). The ability of TPC‑1 and BCPAP cells to uptake 131I was measured and the cell viability was detected by an MTT assay. Finally, the expression of the apoptosis‑associated proteins X‑linked inhibitor of apoptosis (XIAP), cellular inhibitor of apoptosis protein 1 (cIAP1) and caspase‑3 in TCP‑1 and BCPAP cells was determined by western blotting. Western blotting results demonstrated that the expression levels of NF‑κB in TPC‑1 and BCPAP cells were successfully downregulated by RNAi (P<0.05), while analysis of 131I uptake revealed no significant alterations in the 131I uptake ability of cells following RNAi (P>0.05). MTT experiments demonstrated that the inhibition of NF‑κB expression in combination with radiation (131I treatment) led to a marked reduction in cell viability (P<0.05). Furthermore, western blot analysis revealed that the inhibition of NF‑κB expression downregulated the expression levels of XIAP and cIAP1 (P<0.05), while the expression levels of caspase‑3 were upregulated, indicating that the observed reduction in cell viability following NF‑κB inhibition may be due to an increased level of apoptosis. Although NF‑κB inhibition did not affect the 131I uptake of thyroid cancer cells, this inhibition may increase the apoptotic effects of radioactive 131I.

Keywords: thyroid carcinoma; nuclear factor-κB; 131iodine; cell apoptosis; RNA interference.

Figure 1.

Detection of the NF-κB expression by western blotting. (A) Representative western blot bands for NF-κB following transfection of TPC-1 and BCPAP thyroid carcinoma cells with negative control scramble- or NF-κB-RNAi. (B) Quantified results for western blot analysis to confirm successful knockdown of NF-κB. *P<0.05 vs. control. NF-κB, nuclear factor- κB; RNAi, RNA interference; control, cells transfected with negative control scramble-RNAi.

Figure 2.

Effects of inhibition of NF-κB expression on thyroid carcinoma cell uptake of ¹³¹I. TCP-1 and BCPAP thyroid carcinoma cells were transfected with negative control scramble- or NF-κB-RNAi and the cellular uptake of ¹³¹I was subsequently measured. NF-κB, nuclear factor-κB; RNAi, RNA interference; ¹³¹I, ¹³¹iodine; control, cells transfected with negative control scramble-RNAi.

Figure 3.

Detection of the viability of cells by MTT assays. TPC-1 and BCPAP thyroid carcinoma cells were transfected with negative control scramble- or NF-κB-RNAi with or without treatment with ¹³¹I, and MTT assays were subsequently performed to determine the effects on cell viability. Group A represents cells transfected with negative control scramble-RNAi only, group B represents cells transfected with negative control scramble-RNAi and treated with ¹³¹I, group C represents cells transfected with NF-κB-RNAi only and group D represents cells transfected with NF-κB-RNAi and treated with ¹³¹I. *P<0.05 vs. group A; ^#P<0.05 vs. group B and group C. NF-κB, nuclear factor-κB; RNAi, RNA interference; ¹³¹I, ¹³¹iodine.

Figure 4.

Alterations in the protein expression levels of apoptosis-associated proteins in thyroid carcinoma cells. TPC-1 and BCPAP thyroid carcinoma cells were transfected with negative control scramble- or NF-κB-RNAi with or without treatment with ¹³¹I, and western blotting was performed to measure the protein expression of certain apoptosis-associated proteins. Group A represents cells transfected with negative control scramble-RNAi only, group B represents cells transfected with negative control scramble-RNAi and treated with ¹³¹I, group C represents cells transfected with NF-κB-RNAi only and group D represents cells transfected with NF-κB-RNAi and treated with ¹³¹I. *P<0.05 vs. A group; ^#P<0.05 vs. group B and group C. NF-κB, nuclear factor-κB; RNAi, RNA interference; ¹³¹I, ¹³¹iodine; XIAP, X-linked inhibitor of apoptosis; cIAP1, cellular inhibitor of apoptosis protein 1.