Fig. 1

Relative expression levels (A, left) of miR-146b-5p in BBC2 cells relative to normal pre/pro-B cells, ZNF112 relative to normal CD4 + CD8 + cells, BCRF8C relative to normal Sca1+ cells and KG1 relative to peripheral blood mononuclear cells (N = 3 in all cases) shows consistent downregulation. When the same cell lines are treated with the BGJ398 FGFR1 inhibitor (N = 3) miR-146-5p levels increase compared with DMSO treated cells (A, right). Analysis of primary leukemic cells from a BCR-FGFR1 SCLL mouse model (N = 3) shows reduced levels of miR-146b-5p compared with normal BALB/c spleen cells (B, left). The same reduced levels of miR-146b-5p are seen in primary leukemic cells from the ZMYM2-FGFR1 mouse model (N = 3) of SCLL (B, right). Analysis of expression levels in primary human GSE79547 B-ALL samples (N = 20) shows a reverse correlation between miR-146b-5p and FGFR1 expression levels (C). When BBC2 and KG1 cells (N = 3) are treated with the 5-aza-2’deoxycytidine (DAC) methylation inhibitor (D, left) there is a dose-dependent increase in miR-146b-5p expression levels compared with DMSO treated controls. In BBC2 cells in which Dnmt1 is knocked down using two different shRNAs (D, right) there is ~ 10 fold increase in miR-146b-5p expression compared with BBC2 cells treated with a scrambled control (shSCR). Location of the miR-146b-5p target sites within the murine (E, above) and human (F, above) IRAK1 mRNA. Western blot analysis of IRAK1 expression in primary leukemic cells from the syngeneic BCR-FGFR1 model of SCLL shows significantly increased IRAK1 expression levels (E, left below). In BBC2 cells forced to overexpress (OE) miR-146b-5p (E, right below), there is also a highly significant decrease in IRAK1 expression levels compared with cells expressing the empty vector (EV). IRAK1 expression levels are also increased in leukemic cells from a human SCLL model for BCR-FGFR1 transformed CD34+ cells propagated in immunocompromised (NSG) mice (F, left below). In human KG1 cells forced to overexpress miR-146b-5p, IRAK1 level is reduced (F, right below). Analysis of the GSE79547 expression data set from B-ALL patients shows an inverse correlation between IRAK1 expression levels and expression of miR-146b-5p (G). Kaplan-Meyer analysis of an AML cohort [25] (N = 422) demonstrates a highly significant decrease in overall survival in patients showing high level expression of IRAK1 compared with those showing low level expression (H, left). A similar, although slightly less significant relationship between IRAK1 expression and survival is also observed (H, right) in a B-Cell lymphoma (N = 414) data set [26]. In each case the cut off is determined using the SCAN algorithm within the R2 Gemome Analysis and Visualization Platform. ** p < 0.01, *** p < 0.001, **** p < 0.0001