| Abstract: | Although hyperthermia has been used as an effective cancer treatment modality, its effects on metastasis of tumour cells are not clear. Since adhesion molecules play a key role in metastasis, we evaluated how the expression of adhesion molecules is influenced by hyperthermia. Human umbilical vein endothelial cells were incubated in vitro for 1 h. at 39, 42, 43 and 44°C with and without addition of tumour-necrosis factor (TNF) or interferon-gamma (IFN-γ) and the expression of endothelial cell leukocyte adhesion molecule-1 (ELAM-1), intercellular adhesion molecule-1 (ICAM-1) and major histocompatibility complex (MHC) class-II molecule was measured. Expression of MHC class-II molecules and expression of unstimulated constituent ICAM-1's was not reduced by heat treatment. In contrast, expression of cytokine-induced ELAM-1's and ICAM-1's was significantly lower after heat treatment. The adhesion to HUVEC in vitro of HL-60 leukemia cells, which express sialyl-Lewis-x antigen as a ligand to ELAM-1, was diminished after incubation at 42°C and totally lost after treatment at 44°C. This suggests that any decrease in metastasis formation after heat treatment, which is occasionally observed, could be due to a reduced action of TNF or related cytokines on adhesion molecule induction and subsequent membrane expression by the endothelial cell. A possible underlying mechanism involved is a heat-induced alteration or blockage of the biosynthetic pathways required for synthesis of ELAM-1 and ICAM-1 proteins. |
