c HCT116 cells were cultured with peripheral blood monocytes either directly, or were co-cultured using transwell inserts (0.4 μm size). d HCT116 and Hke-3 cells were co-cultured

with THP1 macrophages transfected with nontargeting siRNA (THP1) or siRNA specific for IL-1 or STAT1. The expression of pPDK1, pAKT, AKT and βactin was determined by immunoblotting We showed that, like IL-1β, normal peripheral blood moncoytes and THP1 macrophages phosphorylate AKT and inactivate GSK3β in tumor cells (Fig. 3B). Monocytes were equally potent in inducing PDK1/AKT signaling when they were separated from the tumor cells with a cell impermeable membrane (Fig. 3C), confirming that they induce PDK1/AKT signaling in tumor cells through a soluble factor. To determine whether macrophages induce AKT signaling in tumor cells through IL-1, we co-cultured selleck HCT116 and HKe-3 cells with THP1 macrophages with silenced IL-1β or STAT1, which we established is required for the IL-1 release from macrophages (Kaler et al, in press). We showed that IL-1 or STAT1 deficient THP1 macrophages failed to phosphorylate AKT or activate PDK1 in tumor cells (Fig. 3D), confirming that

IL-1 mediates AKT dependent inactivation of GSK3β in tumor LY2835219 supplier cells. Finally, we showed that IL-1, THP1 macrophages and peripheral blood monocytes failed to phosphorylate AKT and PDK1 in tumor cells expressing dnIκB (Fig. 4A, data not shown), demonstrating that they

activate AKT signaling in a NF-κB dependent manner. The NF-κB and AKT pathways are known to interact and AKT has been about shown to be either downstream or upstream of NF-κB [29, 40]. We showed that transfection of cells with dnAKT (unlike transfection with dnIκB) did not impair the ability of macrophages, IL-1 or TNF to trigger IκBα degradation in HCT116 cells (Fig. 4B) and did not affect NF-κB transcriptional activity (data not shown), confirming that AKT acts downstream of NF-κB. This is consistent with our finding that macrophages and IL-1 failed to activate AKT in cells expressing dnIκB (Fig. 4A). The mechanism whereby NF-κB activates AKT phosphorylation is currently being investigated in the laboratory. Fig. 4 AKT acts downstream of NF-κB: a HCT116 cells were transfected with an empty plasmid (neo) or dnIκB and were cultured with THP1 macrophages or were treated with IL-1 as indicated. b HCT116 cells were transfected with an empty plasmid (neo), dnIκB, dnAKT or CA AKT and were treated as indicated. The levels of pAKT, pPDK1 and IκBα were determined by immunoblotting AKT is Required for Macrophage and IL-1 Induced Wnt Signaling in Tumor Cells To determine whether AKT is required for IL-1 induced Wnt signaling, we transfected HCT116 cells with the TOP-FLASH reporter plasmid in the absence or the presence of dnAKT. The expression of dnAKT was confirmed by immunoblotting with an anti HA antibody (Fig. 5C).