miR-21 has a putative binding site on the SMAD7 3′UTR and is overexpressed in MDS. (A) Targetscan software predicts a strong possibility of miR-21 binding site at position 1122 of the SMAD7 3′UTR with a highly conserved site. (B) Microarray analysis of 41 untreated MDS marrow samples were compared with 10 age-matched controls21 and demonstrate upregulation of miR-21 (mean intensity ± SEM, Student’s t-test, P = .001). (C) Quantitative RT-PCR was done for miR-21 and endogenous control, RNU44, on 19 MDS and 13 age-matched control bone marrow MNCs using the Ambion Taqman miroRNA assay kit. MDS samples had significantly higher expression of miR-21 (*Student’s t-test, P = .04). Both lower- and higher-risk MDS (low-risk MDS, N = 10, P value = .04; high-risk MDS, N = 9, P = .03, Student’s t-test) had higher mean expression when compared with controls.
