Long non-coding RNA ANRIL promotes the invasion and metastasis of thyroid cancer cells through TGF-β/Smad signaling pathway

OBJECTIVE To investigate the effect of antisense non-coding RNA in the INK4 locus (ANRIL) on invasion and metastasis of thyroid cancer (TC). RESULTS ANRIL expression was significantly up-regulated in TC tissues and cells (P < 0.001), and ANRIL expression was significantly different regarding histological grade and LNM (both P < 0.01). The siRNA-mediated ANRIL silencing inhibits proliferation, invasion, and metastasis of TPC-1 and SW579 cells, and lung metastasis, which can be reversed by TGF-β1 siRNA. The mRNA levels of p15INK4b, p14ARF and p16INK4a in TPC-1 and SW579 cells increased significantly after silencing ANRIL (all P < 0.001), and TGF-β1 siRNA could reverse the ANRIL siRNA induced increase of p15INK4b; expressions of TGF-β1 and p-Smad2/3 were increased after silencing ANRIL (both P < 0.05). MATERIALS AND METHODS TC and adjacent normal tissues were collected from 105 TC patients. LncRNA ANRIL expressions were detected by qRT-PCR. The siRNA ANRIL and siRNA TGF-β1 were constructed for TPC-1 and SW579 cell line transfection: si-ANRIL group, si-TGF-β1 group, si-ANRIL + si-TGF-β1 group, negative control group and blank group. Effects of ANRIL silencing on proliferation, invasion and metastasis of TC cells was detected by MTT assay, Transwell assay and tail vein injection of nude mice in vitro and in vivo. TGF-β1 and p-Smad2/3 expressions in TGF-β/Smad signaling pathway were detected by western blot. CONCLUSIONS ANRIL may reduce p15INK4B expression through inhibiting TGF-β/Smad signaling pathway, promoting invasion and metastasis of TC cells, and the silencing of ANRIL inhibits the invasion and metastasis of TPC-1 cells.