Cellular tumorigenicity in nude mice: Correlation with cell growth in semi-solid medium

Cultured cells derived from either normal or malignant tissues of several species have been tested by injection into the immune-deficient nude mouse in order to determine the cellular properties which are associated with tumorigenicity in vivo. Results show that one in vitro property consistently correlated with neoplastic growth in nude mice is the ability of the cell to form spherical colonies in a semi-solid growth medium such as methyl cellulose suspension. Cellular tumorigenicity is not determined solely by the malignancy of the tissue of origin, since cells derived from nonmalignant tissues become tumorigenic when they are no longer anchorage dependent for growth. In addition, acquisition of infinite growth potential in heteropioid cell lines is not in itself sufficient to confer tumorigenic capacity on the cells. These results suggest that the degree of cell growth in methyl cellulose is a useful parameter in vitro for predicting tumorigenicity in the animal, and also demonstrate the potential usefulness of the nude mouse for analysis of cellular malignancy irrespective of the tissue or species of origin.