Anti-inflammatory macrophages activate invasion in pancreatic adenocarcinoma by increasing the MMP9 and ADAM8 expression

Patients with chronic pancreatitis with local inflammation have high risk for pancreatic cancer. The aim of this study was to examine the role of the inflammatory cells in the invasion of pancreatic cancer cells, focusing on the involvement of a disintegrin and metalloproteinase 8 (ADAM8) and matrix metalloproteinase 9 (MMP9) proteins. ADAM8 expression is associated with worse survival of pancreatic cancer patients. Monocytes from healthy donors were differentiated into macrophages. Pancreatic adenocarcinoma cells were cultured either alone or with differentiated macrophages. The cancer cell migration rate in Matrigel was measured by imaging fluorescently stained cells for 24 h. After invasion, cells were sorted into CD14 positive/negative macrophages and cancer cells with magnetic separation. The expression of ADAM8 and MMP9 was measured by the real-time PCR. Protein-level expression of ADAM8 and MMP9 was analyzed by Western blotting. In two series, siRNA technique was used to reduce either ADAM8 or MMP9 expression in the cancer cells. The coculture with macrophages increased cancer cell migration rate in Matrigel, and increased ADAM8 and MMP9 mRNA expression and protein level in the cancer cells. Reduction of ADAM8 expression with siRNA in the cancer cells decreased macrophage-induced migration rate of the cancer cells from 11.7 ± 0.3 μm/h to 9.0 ± 0.2 μm/h (p < 0.01), and reduction of MMP9 expression decreased the migration rate to 10.1 ± 0.2 μm/h (p < 0.01). Anti-inflammatory macrophages increase pancreatic cancer cell migration rate in basement membrane matrix by inducing ADAM8 and MMP9 expression in cancer cells, thereby possibly enhancing the invasiveness of cancer.