Imaging of cancer invasion and metastasis using green fluorescent protein

The use of green fluorescent protein to fluorescently tag tumour cells has allowed investigators to open the "black box" of metastasis in order to vis ualise the behaviour of tumour cells in living tissues. Analysis of cells l eaving the primary tumour indicates that highly metastatic cells are able t o polarise more effectively towards blood vessels while poorly metastatic c ells fragment more often when interacting with blood. In addition, there ap pear to be greater numbers of host immune system cells interacting with met astatic tumours. After arresting in target organs such as the lungs or live r, most tumour cells become dormant or apoptose. A small fraction of the ar rested cells form metastases. In some target organs, migration of tumour ce lls may enhance the ability to form metastases. (C) 2000 Elsevier Science L td. All rights reserved.