TNFα Mediated IL-6 Secretion Is Regulated by JAK/STAT Pathway but Not by MEK Phosphorylation and AKT Phosphorylation in U266 Multiple Myeloma Cells
Figure 3
Effect of TNFα on activation of MAPK, JNK, and PI3K/AKT signaling pathways and effect of indicated inhibitors on IL-6 secretion. (a) U266 and IM9, multiple myeloma cell lines were starved for 8 h and then treated with or without 1 ng/mL TNFα for 10 min. Each cell line was harvested and prepared for immunoblotting. Upregulation of MAPK, JNK, and PI3K/AKT by TNFα was examined with indicated antibodies. GAPDH was used to ensure equal loading. (b) U266 cells were pretreated with various signal inhibitors for 1 h, respectively. These cells were then stimulated with TNFα for 10 min, and cell supernatants were harvested for ELISA to determine IL-6 concentration induced by TNFα. Bars represent the mean ± SEM from three independent experiments. c: control; 1: TNFα only; 2: TNFα plus 10 M PD98059; 3: TNFα plus 20 M LY294002; 4: TNFα plus 10 M SB203580; 5: TNFα plus 40 nM JNK inhibitor II.
