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

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. 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. 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. These findings indicate that BANCR may contribute to the tumorigenesis of PTC through regulation of cyclin D1 and TSHR.