SNHG9, a Papillary Thyroid Cancer Cell Exosome-Enriched lncRNA, Inhibits Cell Autophagy and Promotes Cell Apoptosis of Normal Thyroid Epithelial Cell Nthy-ori-3 Through YBOX3/P21 Pathway

Thyroid cancer is the most common type of endocrine malignancy. Although the general prognosis is good, the treatment of advanced disease is still challenging. Exosomes are vesicle units containing specific components that transmit information between cells. In order to explore its role in papillary thyroid cancer (PTC), our study screened exosome enriched lncRNA SNHG9 by lncRNA chip and explored its biological function. We used lncRNA chips combined with bioinformatics analysis to screen lncRNA SNHG9 enriched in exosomes. GO analysis suggested its relationship with autophagy and apoptosis. Quantitative PCR showed SNHG9 was highly expressed in PTC cells and exosomes and its correlation with PTC tumor size was analyzed by clinical characteristics. SNHG9 could inhibit the protective cell autophagy induced by starvation of human normal thyroid epithelial cell line Nthy-ori-3 and promote its apoptosis through PTC cell exosomes. RNA-pull down combined with protein spectrum showed that SNHG9 could interact with YBOX3. Western blot and RNA immunoprecipitation further confirmed their interaction. Western blot showed that SNHG9 could induce degradation of YBOX3, thus interfering with the stability of P21 mRNA and inducing cell apoptosis. In conclusion, our study identified SNHG9 as a PTC cell exosome-enriched lncRNA. SNHG9 could inhibit cell autophagy and promote apoptosis of Nthy-ori-3 cell through YBOX3/P21 pathway.

Vitamin E ameliorates iodine-induced cytotoxicity in thyroid

Acute and excessive iodine supplementation leads to iodine-induced thyroid cytotoxicity. Excessive oxidative stress has been suggested to be one of the underlying mechanisms in the development of thyroid cytotoxicity. The aim of this study was to investigate whether vitamin E (VE), an important antioxidant, could ameliorate iodine-induced thyroid cytotoxicity. A goiter was induced in rats by feeding a low-iodine (LI) diet for 12 weeks. Involution of hyperplasia was obtained by administering a twofold physiological dose of iodine in feeding water with/without the supplementation of 25-, 50-, or 100-fold physiological dose of VE in the LI diet for 4 weeks. In iodine-supplemented rats, thyroid epithelial cell ultrastructure injuries remained and were more severe. Relative weights of iodine-induced involuting glands were significantly reduced compared with the goiter, but still higher than control. Immunohistochemistry indicated that the expression of 4-hydroxynonenal, 8-hydroxyguanine, peroxiredoxin 5, and CD68 in thyroid increased (P<0.01), whereas thioredoxin reductase 1 decreased (P<0.01). VE supplementation attenuated thyroid cytotoxicity induced by iodine. A 50-fold VE dose was optimal in attenuating twofold iodine-induced thyroid cytotoxicity. However, VE supplementation did not reduce the weight or relative weight of the iodine-induced involuting gland. These results show that excess iodine leads to thyroid damage and VE supplementation can partly ameliorate iodine-induced thyroid cytotoxicity.