The expression of adhesion molecules and the influence of inflammatory cytokines on the adhesion of human pancreatic carcinoma cells to mesothelial monolayers

Objectives: Pancreatic cancer has a tremendously deplorable prognosis. Peritoneal dissemination frequently occurs after surgical resection of the tumor. Specific adhesion molecules may be of great importance in local turner recurrence. These adhesion molecules may be influenced by inflammatory cytokines produced during surgery. The aim of this study was to investigate the effects of inflammatory cytokines, interleukin-1 beta (IL-1 beta), interleukin-6 (IL-6), and tumor necrosis factor-alpha (TNF-alpha), on the interaction between pancreatic tumor cells and mesothelial cells. Methods: An experimental in vitro model was designed using Panc-1, MiaPaCa-2, and BxPC-3 pancreatic carcinoma cell lines. Primary cultures of mesothelial cells were incubated with the inflammatory cytokines, and after the incubation, the adherence of the different pancreatic cell lines was measured. By means of immunocytochemical staining and enzyme immunoassay, the expression of adhesion molecules (ICAM-1, VCAM-1, and CD44) and counterparts (LFA-1 and VLA-4) was investigated. Results: Preincubation of the mesothelial monolayer with IL-1 beta or TNF-alpha resulted in enhanced tumor cell adhesion of the MiaPaCa-2 and BxPC-3 cells. The amount of stimulation for the MiaPaCa-2 cells was more than 100% versus the control situation and for BxPC-3 cells between 20% to 35%. IL-6 did not affect the tumor cell adhesion of the MiaPaCa-2 and BxPC-3 cells. The adherence of Panc-1 was not enhanced after preincubation of the mesothelial monolayers with the inflammatory cytokines. Mesothelial cells show a significant enhancement of expression of ICAM-1, VCAM- 1, and CD44 after stimulation with IL-10 and TNF-alpha. Conclusions: The presented results prove that IL-1 beta and TNF-alpha are significant stimulating factors in pancreatic tumor cell adhesion in vitro and may therefore account for tumor recurrence to the peritoneum in vivo. The immunocytochemical staining results demonstrate that ICAM-1 and CD44 important adhesion molecules and interference with their function may decrease the