Downregulation of <i>BANCR</i> Promotes Aggressiveness in Papillary Thyroid Cancer via the MAPK and PI3K Pathways

Abstract

Recent evidence indicates that long non-coding RNAs play important roles in tumorigenesis and cancer progression. <i>BRAF</i>-activated non-protein coding RNA (<i>BANCR</i>) is a novel and potential regulator of cancer cell proliferation and migration. However, little is known regarding the role of <i>BANCR</i> in papillary thyroid cancer (PTC). The current study used quantitative PCR to demonstrate that <i>BANCR</i> was significantly downregulated in 60 paired PTC tissues compared with normal tissues. In addition, <i>BANCR</i> was significantly correlated with lymph node metastasis (<i>p</i> = 0.02). Furthermore, Cell Counting Kits and Transwell assays were used to demonstrate that knocking down <i>BANCR</i> with short hairpin RNA (shRNA) transfection significantly promoted the proliferation and invasion of PTC cell lines. The flow cytometric analysis of apoptosis and the cell cycle revealed that the overexpression of <i>BANCR</i> inhibited cancer cell proliferation and invasion, which was associated with the induction of cell-cycle G2/M phase arrest and increased apoptosis. Moreover, western blotting was used to show that the MAPK and PI3K-Akt pathways were aberrantly activated during <i>BANCR</i>-mediated PTC cell proliferation and migration. These findings revealed that <i>BANCR</i> functions as a tumor suppressor during thyroid carcinogenesis.