MECHANISMS INVOLVED IN METASTASIS ENHANCED BY INFLAMMATORY MEDIATORS

The enhancement of tumor metastasis by concurrent inflammatory process es is mainly due to the cytokines TNF and IL-1. In the case of TNF thi s effect is not restricted to metastasis models as measured by in vivo colony formation but also found in experimental model systems of spon taneous metastasis. Direct effects on the tumor cells or interference with the host NK cell system did not seem to account for the observed TNF effect. Experimental evidence from different test systems rather p oints to TNF- or IL-1-induced enhanced adhesion of tumor cells to the endothelial cell layer as the underlying mechanism. Blocking of integr in-matrix interactions with monoclonal antibodies or competing peptide s inhibited tumor cell adhesion to endothelioma cells in vitro and lun g colony formation of tumor cells in vivo. (C) 1994 Wiley-Liss, Inc.