Polymorphonuclear cells stimulate the migration and metastatic potential of rat sarcoma cells

The tumour microenvironment, which is largely composed of inflammatory cells, is a crucial participant in the neoplastic process through the promotion of cell proliferation, survival and migration. Neutrophil polymorphonuclear cells (PMNs) induce inflammatory reactions that can be either cytotoxic for tumour cells or can promote tumour growth and metastasis. Previously, we have reported a spontaneous metastasis tumour model that has tumour PMNs infiltration, and metastasis, to liver and spleen. The aim of this study was to evaluate the PMNs influences on the tumour cell invasion and metastatic properties. We analysed intercellular adhesion molecule-1 (ICAM-1), urokinase-type plasminogen activator receptor (uPAR), MT1-MMP (membrane type 1-matrix metalloproteinase) and MMP2 protein expression in TuE-t cells cultured with PMNs or PMNs-conditioned medium isolated from tumour bearing and normal rats. The interaction between tumour cells and PMNs induced a decrease in ICAM-1 expression in tumour cells as well as an increase in MMP2 and tumour cell motility. Besides, conserved expression of uPAR and MT1-MMP in tumour cells was also demonstrated. The up-regulation in MMP2 associated with uPAR and MT1-MMP conserved expression may be related to an increased extracellular matrix proteolysis. These results showed that the interaction of tumour cells with PMNs could favour tumour cell spreading through the promotion of a tumour invasive phenotype.