Control nc mimic

In order to overexpress hsa_circ_0023409 in MKN45 cells, a fragment of cDNA was cloned into PLCDH-cir vector (Ribobio, Guangzhou, China) and lentivirus was constructed by Hanbio (Shanghai, China). We purchased the lentivirus-containing short hairpin RNA (shRNA) targeting hsa_circ_0023409 from GenePharma (Shanghai, China). The shRNAs were transfected into the HGC-27 cell lines using Lipofectamine 3000 (Invitrogen, Carlsbad, CA, USA) according to the manufacturer’s instructions. Forty-eight hours after transfection, qRT-PCR was performed to verify the transfection efficiency.
For transient transfection, miR-542-3p mimics and the negative control (NC) mimic, as well as the miR-542-3p inhibitor were purchased from RiboBio. The miR-542-3p mimics or its NC was transfected into HGC-27 cells. MKN45 cells were transfected with miR-542-3p inhibitor or its NC inhibitor. The transfections were mediated by Lipofectamine 3000 (Invitrogen, Carlsbad, CA, USA) according to the manufacturer’s instructions for 6 h at 37°C.