Adhesion Mechanisms in Liver Metastasis

Abstract

The liver is a major target organ for metastasis formation by many tumor types, including lung carcinoma (1). The aim of the present study is the elucidation of mechanisms underlying the interactions between tumor cells and liver cells, which lead to the incorporation of a tumor cell into liver tissue, and thus enable the formation of a metastatic tumor. The approach was, first to observe by electron microscopy the invasion of tumor cells into the intact liver, both in vivo and perfused in situ; second, to isolate liver cells and to reproduce the interactions that had been observed in vivo, by addition of tumor cells to short-term cultures of these liver cells; and third, by perturbing the in vitro interations mainly by antibodies directed against either the tumor cells or the liver cells. The studies in vivo indicated that the invasion mechanism was qualitatively comparable for different tumor cell types although large quantitative differences were seen particularly between, on the one hand, diffusely infiltrating lymphoma cells and, on the other hand, tumor cell types which gave rise to nodular metastases. In contrast, the in vitro experiments clearly showed that at the molecular level mechanisms were quite distinct, particularly for lymphoma as compared to cacinoma cells.