Figure 1

STAT3 is a potential therapeutic target in CLL. (a) STAT3 is overexpressed in CLL cell lines and patient cells. (i) JVM-3 cells, Mec-2 cells, PBMCs from two different normal blood donors and PBMCs from four CLL patients were lysed and western blot analysis was performed. The final image was created by grouping different parts of the same film of the same gel as indicated by the black dividing line. (ii) CD19+ B cells were isolated from blood donated by healthy donors and protein levels were compared to JVM-3 cells by western blot analysis. (b) Knockdown of STAT3 induces cell death in CLL cells. JVM-3 cells were transfected with several clones of STAT3 shRNA. (i) Flow cytometric analysis was performed to determine % dead cells 24–96 h after doxycycline induction and (ii) western blot analysis done. Cells nucleofected with TE buffer containing no plasmid were used as a control. An aliquot of 1 μg ml⁻¹ doxycycline was used to induce the expression of STAT3 shRNA 24 h after nucleofection and doxycycline level was maintained during the assay period. The graph represents two independent experiments. Student’s t-test was used for statistical analysis, ***P<0.0001, **P<0.05. The final western blot image was created by grouping different parts of the same film of the same gel as indicated by the black dividing line. (c) STAT3 inhibition reduces viability of CLL cell lines and patient cells. (i) PBMCs from three normal donors and three CLL patients, (ii) JVM-3 cells and (iii) Mec-2 cells were treated with Stattic for 24 h and cell viability was determined by the MTS assay. (ii) Western blotting analysis in JVM-3 confirms the effectiveness of Stattic treatment. The graphs represent results from three independent experiments.