To investigate the effect of serine/threonine-protein kinase B-Raf (BRAF)-activated long-chain non-coding RNA (lncRNA-BANCR) on apoptosis and autophagy in thyroid carcinoma cells and the underlying mechanisms.
 Methods: RT-PCR was used to detect the expression of lncRNA-BANCR in thyroid carcinoma and normal thyroid tissues. The association between lncRNA-BANCR and clinicopathological data was analyzed in patients with thyroid cancer. Cell counting kit-8 (CCK-8) was used to detect the effect of lncRNA-BANCR on the proliferation of thyroid cancer cells. The effect of lncRNA-BANCR on the apoptosis of thyroid carcinoma cells was detected by flow cytometry. Transwell invasion assay was used to detect the effect of lncRNA-BANCR on the invasive ability of thyroid cancer cells. Western blot was used to detect the changes of autophagy proteins LC3-I and LC3-II after the lncRNA-BANCR expression was suppressed.
 Results: Compared with normal thyroid tissues, the expression level of lncRNA-BANCR in thyroid carcinoma tissues was elevated (P<0.05). The expression of lncRNA-BANCR was positively related to the pathological stage of thyroid carcinoma and the lymph node metastasis. Inhibition of lncRNA-BANCR expression attenuated the proliferation and invasion ability of thyroid cancer cells (both P<0.05); but the apoptosis was enhanced (P<0.05); the expression levels of autophagy protein LC3-I and LC3-II were also increased (P<0.05).
 Conclusion: The expression level of lncRNA-BANCR affects the proliferation, invasion and apoptosis of thyroid cancer cells through modulation of autophagy behavior.
Apoptosis ; Autophagy ; Cell Proliferation ; Gene Expression Regulation, Neoplastic ; Humans ; Neoplasm Invasiveness ; Proto-Oncogene Proteins B-raf ; metabolism ; RNA, Long Noncoding ; metabolism ; Serine ; metabolism ; Threonine ; metabolism ; Thyroid Gland ; cytology ; metabolism ; Thyroid Neoplasms ; metabolism ; pathology

B-RafV600E mutant is found in 40-70% of papillary thyroid carcinoma (PTC) and has an important role in the pathogenesis of PTC. The sodium iodide symporter (NIS) is an integral plasma membrane glycoprotein that mediates active iodide transport into the thyroid follicular cells, and B-RafV600E has been known to be associated with the loss of NIS expression. In this study, we found that B-RafV600E inhibited NIS expression by the upregulation of its promoter methylation, and that specific regions of CpG islands of NIS promoter in B-RafV600E harboring PTC were highly methylated compared with surrounding normal tissue. Although DNA methyltransferase 3a and 3b (DNMT3a,3b) were not increased by B-RafV600E, DNMT1 expression was markedly upregulated in PTC and B-RafV600E expressing thyrocytes. Furthermore, DNMT1 expression was upregulated by B-RafV600E induced NF-kappaB activation. These results led us to conclude that NIS promoter methylation, which was induced by B-RafV600E, is one of the possible mechanisms involved in NIS downregulation in PTC.
Base Sequence ; Carcinoma/*genetics/metabolism/pathology ; Cells, Cultured ; DNA (Cytosine-5-)-Methyltransferase/analysis/*genetics/metabolism ; DNA Methylation ; Down-Regulation ; *Gene Expression Regulation, Neoplastic ; Humans ; Molecular Sequence Data ; *Point Mutation ; Promoter Regions, Genetic ; Proto-Oncogene Proteins B-raf/*genetics/metabolism ; Symporters/analysis/*genetics/metabolism ; Thyroid Gland/cytology/metabolism/pathology ; Thyroid Neoplasms/*genetics/metabolism/pathology ; Up-Regulation