[An in vitro model of tumour cell invasion]

Tumorigenicity and malignancy of transformed cells have thus far been demonstrated in animal experiments only. Therefore it seems desirable to develop an in vitro model to study aspects of malignancy such as invasive growth and metastasis in order to provide information about the in vivo behavior of transformed cells. In this study a tissue culture system has been developed which was used to investigate two pivotal characteristics of malignant cells: migration and production of proteases. Proteases are enzymes that degrade extracellular matrix and also may be capable of destroying cells directly. In order to study behavior of malignant cells in vitro, rat liver epithelial cells were transfected with the ras oncogene. Expression of several genes was induced, including a protease and a protease inhibitor. The cells were found to be morphologically and neoplastically transformed and to migrate constitutively. Furthermore the cells grew in semi-solid medium, which is another property of transformed cells. These in vitro characteristics correlated with in vivo behavior (invasive growth in athymic mice). It is hoped that this correlation will enable further studies to be carried out with tissue culture systems, so limiting the use of live animals. This study has been published in detail (Zoller, J., 1991. Biochemische und molekularbiologische Analyse der Invasion von Tumorzellen. Konstanzer Dissertationen 301. Konstanz: Hartung-Gorre Verlag).