Fig. 7

Snail inhibits transcription of miR-548ac under acidic conditions. a, b The expression of miR-548ac was measured by qPCR when HUVECs were transfected with Snail siRNAs or overexpression plasmid in the normal or acidic medium. c The schematic shows that the host-gene of miR-548ac harbors four E-box elements (E-box-1, E-box-2, E-box-3, E-box-4) that may be combined by Snail protein. d The ChIP analysis of the binding capacity between Snail protein and the E-box sequences on the promoter of miR-548ac host-gene in the Control, Acidity, and Acidity with Snail knockdown groups, respectively. e We constructed four luciferase reporter plasmids to identify the promoter transcriptional activity of miR-548ac host-gene, wild type (WT) without any mutation, MUT-1 with E-box-3 mutation, MUT-2 with E-box-2 mutation, and MUT3 with both mutations of E-box-2 and E-box-3. f The luciferase activity of WT, MUT-1, MUT-2, MUT-3 plasmids co-transfected with Snail overexpression plasmid or control vector. g The schematic summary shows that in the acidic environment-induced low expression of miR-548ac mediated the YB-1/Snail positive feedback pathway leads to the metastasis of pancreatic cancer cells by increasing the permeability of HUVECs