Interleukin-1alpha enhances IL-8 secretion through p38 mitogen-activated protein kinase and reactive oxygen species signaling in human pancreatic cancer cells.

BACKGROUND: Interleukin (IL)-1alpha plays an important role in modulating the expression of various growth factors and angiogenic factors in tumor cells. In here, we investigated effect of IL-1alpha on IL-8 secretion in human pancreatic cancer cells and underlying signal transduction pathways.

MATERIAL/METHODS: IL-8 expression and secretion by pancreatic cancer cells was measured by Western blot and enzyme-linked immunosorbent assay (ELISA), respectively. Activation of extracellular signal regulated kinases-1/2 (ERK-1/2), p38 mitogen-activated protein kinase (MAPK), c-jun aminoterminal kinase, Akt, and nuclear factor-kappaB (NF-kappaB) was determined by Western blot. Involvement of reactive oxygen species (ROS) were examined by measuring the H2O2. Activity of activator factor-1 (AP-1) and NF-kappaB was examined by electrophoretic mobility sift assay (EMSA). Proliferation of human umbilical vein endothelial cells (HUVECs) was determined by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide dye reduction method and cell count.

RESULTS: IL-1alpha modulated IL-8 secretion and induced activation of ERK-1/2 and p38 MAPK. Specific inhibitors for MEK-1 and p38 MAPK suppressed IL-8 secretion. IL-1alpha also induced production of ROS. Exogenous H2O2 enhanced IL-8 secretion and N-acetyl cysteine (NAC) prevented IL-1alpha-induced ROS production and IL-8 secretion. EMSA confirmed that IL-1alpha increased DNA-binding activity of AP-1 and NF-kappaB. Inhibitors and ROS scavenger studies revealed that upstream signalings for AP-1 and NF-kappaB were MAPK and ROS, respectively. Conditioned media from pancreatic cancer cells pretreated with IL-1alpha remarkably stimulated in vitro HUVECs growth.

CONCLUSIONS: These results suggest that MAPK/AP-1 and ROS/NF-kappaB signaling pathways are involved in IL-1alpha-induced IL-8 secretion and that these paracrine signaling pathways enhance endothelial cell proliferation.