Fig. 5.

Characterization of IGF2BP1 as downstream target of LIN28B via let-7 microRNA. a Relative let-7a microRNA expression of TF-1a after LIN28B knockdown as quantified by qPCR. *p < 0.05; **p < 0.01. b Potential let-7 miRNA binding sequence of 3′-UTR of IGF2BP1. c HEK293T cells were co-transfected with 0.5 μg of pGL3.0, 2 μg of IGF2BP1 reporter gene, and 10 ng of Renilla vector as indicated on the x-axis in 1 ml of RPMI 1640 growth medium for 24 h prior to lysis for measuring the luminescence. All samples were normalized with renilla luciferase to ensure equal transfection efficiency. Cells transfected with control siRNA (NC siRNA) and without miRNA were used as negative controls. d let-7a and let-7b mimetic were chemically transfected into TF-1a cells and cultured for 72 h prior protein extraction for Western blot analysis. e Assessment of IGF2BP1 protein levels in HEL cells transduced with Scramble shRNA or IGF2BP1 specific shRNAs after 72 h. f Cell proliferation assays of HEL cells treated with IGF2BP1-specific shRNA3, shRNA4 (left panel) or let-7a mimic, let-7b mimics at indicated time points (n = 3, mean ± SD, *p < 0.05, **p < 0.01). g LIN28B expression primary AML cell was correlated with increased IGF2BP1 and decreased let-7a. Bone marrow samples from 17 patients with AML were collected at diagnosis and subjected to qPCR for LIN28B, IGF2BP1, and let-7a miRNA levels. The Pearson r values and p values were determined with GraphPad Prism software