Abstract
1693
Objectives It has been suggested that sodium iodide symporter (NIS) interfering siRNA could reduce the uptake of radioactive iodine (RAI) and might decrease the salivary dysfunction after RAI treatment. We evaluated the feasibility of NIS interfering siRNA for protecting salivary gland after RAI treatment in rat model.
Methods siRNA interfering NIS was designed and was validated for the efficacy of silencing NIS using real time PCR in FRTL-5 cells. NIS interfering siRNA 32 ug was injected to rat submandibular salivary gland via 28 G syringe 12 hour before administration of 370 MBq I-131. For control, random sequence siRNA and normal saline were injected in the same way resulting in 3 groups (NIS group, Random group, Normal saline group). Salivary function was assessed 3, 6, 11 weeks after I-131 administration. The salivary secretion of each rat was measured after subcutaneous injection of 3 mg/kg pilocarpine. The salivary secretion was expressed as the volume of saliva secreted per g of body weight. The salivary functions of 3 groups were compared using Kruskal-Wallis one-way analysis of variance.
Results On real time PCR, NIS interfering siRNA decrease moderately the NIS expression in FRTL-5. The mean baseline salivary function of NIS, Random, Normal saline groups revealed, 0.0039, 0.0048, 0.0044 ml/g, respectively (p=0.926). At 11 weeks after administration of I-131, salivary function was improved in NIS and Random groups (0.0058 and 0.0055 ml/g, respectively) but, that of Normal saline group was decreased (0.0043 ml/g). However, no significant difference was observed between 3 groups (p=0.50).
Conclusions NIS interfering siRNA might protect salivary gland after RAI treatment. Further investigation would be warranted for the mechanism of siRNA to protect salivary gland