Figure 6. Blocking the PI3Kδ/PKCβ signaling pathways downregulates Mcl-1 and sensitizes stroma-cultured CLL cells to ATO.
(A) 8–10 × 106 CLL cells were treated for 1 h with 2.5 μM idelalisib (Idela), 2.5 μM sotrastaurin (Sotras), 5 μM UO126 (UO), or vehicle, and cultured on HS-27A cells for 24 h, with or without 2 μM ATO. Western blotting analyses of the indicated proteins are shown for a representative patient. The quantitation of proteins with significant changes in their expression on the four samples analyzed (P40, P41, P42, P48) is also shown. (B) Average cell viability of the four samples used in (A), determined by flow cytometry. (C) CLL cells from the same patients used in (A) were treated or not with inhibitors of NF-κB (NF-κB-i), STAT3 (Stattic), or MEK (UO126) and cultured on HS-27A cells as above. The indicated proteins were analyzed by Western blotting. The results from a representative sample and the quantitation of all samples analyzed are shown. *P ≤ 0.05; **P ≤ 0.01; ***P ≤ 0.001.