Transfection of cell lines

The siRNA (small interfering RNA) sequences were as follows: NEAT1 ({"type":"entrez-nucleotide","attrs":{"text":"NR_131012","term_id":"764020159","term_text":"NR_131012"}}NR_131012) siRNA1 (5′-GCCAUCAGCUUUGAAUAAAUU-3′), NEAT1 siRNA2 (5′-GGUGUUAUCAAGUGAAUUAUU-3′), NEAT1 siRNA3 (5′-GCCUUGUAAAUGCCU AUAUUU-3′). Synthetic sequence-scrambled siRNA from Invitrogen were used as negative controls. Hsa-miRNA-377-3p mimic and mimic negative control, hsa-miRNA-377-3p inhibitor and inhibitor negative control were purchased from RiboBio Co., Ltd. (Guangzhou, China). For convenience, hsa-miRNA-377-3p mimic and mimic negative control, hsa-miRNA-377-3p inhibitor and inhibitor negative control were simply referred to as miR-377-3p mimic and miR mimic NC, miR-377-3p inhibitor and miR inhibitor NC, respectively. The target sequence of shRNA-NEAT1 was as follows: GCCATCAGCTTTGAATAAATT. Human NEAT1 gene ({"type":"entrez-nucleotide","attrs":{"text":"NR_131012","term_id":"764020159","term_text":"NR_131012"}}NR_131012) and E2F3 gene ({"type":"entrez-nucleotide","attrs":{"text":"NM_001949","term_id":"1519245016","term_text":"NM_001949"}}NM_001949) was ligated into pGCMV/MCS/RFP/Neo vector (GenePharma, Shanghai, China). The empty vector was used as a negative control (NC). Stable cell lines were created by selection with Geneticin (G418; Invitrogen, CA, USA). The NEAT1 and control siRNAs, miR-377-3p mimic and miR mimic NC, miR-377-3p inhibitor and miR inhibitor NC, shRNA-NEAT1, pGCMV/NEAT1 and NC, pGCMV/E2F3 and NC were transfected into A549 and H1299 cells at approximately 50%–70% confluence, which were cultured on six-well plates using Opti-MEM I and Lipofectamine 2000 (Invitrogen, CA, USA) according to the manufacturer's protocol.