Experimental metastatic ability of H-ras-transformed NIH3T3 cells.

We have used a quantitative "experimental" metastasis assay in the embryonic chick, an immunodeficient host, to examine in vivo growth properties of ras oncogene-transformed NIH3T3 cells. We found that two independently derived populations of NIH3T3 cells that had been morphologically transformed with the T24 human H-ras oncogene were able to grow in vivo following i.v. injection. Nontransformed control NIH3T3 cells with normal morphology did not grow in this assay. Spontaneously arising morphological transformants from control NIH3T3 cell populations were also tested and did not grow in this assay. We conclude that the H-ras gene can confer experimental metastatic ability on nonmetastatic NIH3T3 cells, that the ras gene alters the cells in some way beyond in vitro morphological transformation, and thus that the in vitro transformation assay detects only part of the malignant phenotype of these cells.