HIF-1α regulates genes involved in chemotaxis and cell adhesion in CLL. (A) Relative expression of HIF-1α and common HIF-1α target genes in MEC-1 cells upon HIF-1α stable silencing (shHIF-1α) with respect to control cells (shCTRL). Data represent mean values ± SEM of 3 independent experiments. (B) Immunoblot of HIF-1α in shHIF-1α and shCTRL MEC-1 cells shows constitutive expression of HIF-1α and downregulation by shRNA both at basal conditions and upon further protein stabilization with CoCl₂. Representative experiment of 2 with similar results. (C) Expression of Cell Adhesion Molecules (left panel) and Cytokine-Cytokine Receptor Interaction (right panel) gene sets from the Kyoto Encyclopedia of Genes and Genomes in microarray data from MEC-1 shHIF-1α cells compared with shCTRL cells (respective normalized enrichment score and false discovery rate of 1.98 and 0.008 for shHIF-1α cells and 1.74 and 0.078 for shCTRL cells). The bar-code plot indicates the position of the genes belonging to each gene set on the expression data rank sorted by its association with HIF-1α knockdown, with red and blue colors indicating overexpression and underexpression, respectively, in the HIF-1α-silenced group. (D-E) Downregulation of HIF-1α target genes involved in cell adhesion and cytokine interaction in MEC-1 cells upon independent shHIF-1α-mediated silencing (D) and in primary CLL B cells (n = 10) after electroporation with a control (CTRL) or HIF-1α-targeting oligonucleotide (HIF-1α) (E). Data represent mean values ± SEM of 3 (D) and 10 (E) independent experiments. SEM, standard error of the mean.