BRAF-Activated Long Noncoding RNA Modulates Papillary Thyroid Carcinoma Cell Proliferation through Regulating Thyroid Stimulating Hormone Receptor

PURPOSE: The importance of long noncoding RNAs (lncRNAs) in tumorigenesis has recently been demonstrated. However, the role of lncRNAs in development of thyroid cancer remains largely unknown. MATERIALS AND METHODS: Using quantitative reverse transcription polymerase chain reaction, expression of three lncRNAs, including BRAF-activated long noncoding RNA (BANCR), papillary thyroid cancer susceptibility candidate 3 (PTCSC3), and noncoding RNA associated with mitogen-activated protein kinase pathway and growth arrest (NAMA), was investigated in the current study. RESULTS: Of the three lncRNAs (BANCR, PTCSC3, and NAMA), expression of BANCR was significantly up-regulated while PTCSC3 and NAMA were significantly down-regulated in papillary thyroid carcinoma (PTC) compared to that in normal tissue. BANCR-knockdown in a PTC-derived cell line (IHH-4) resulted in significant suppression of thyroid stimulating hormone receptor (TSHR). BANCR-knockdown also led to inhibition of cell growth and cell cycle arrest at G0/G1 phase through down-regulation of cyclin D1. In addition, BANCR was enriched by polycomb enhancer of zeste homolog 2 (EZH2), and silencing BANCR led to decreased chromatin recruitment of EZH2, which resulted significantly reduced expression of TSHR. CONCLUSION: These findings indicate that BANCR may contribute to the tumorigenesis of PTC through regulation of cyclin D1 and TSHR.