Cellular and molecular changes in 3T3 cells transformed spontaneously or by DNA transfection

Transformed cell lines have been selected following exposure of NIH 3T3 cells to a calcium phosphate precipitate containing DNA from: the human colon carcinoma cell line, SW 480; the cloned Harvey sarcoma virus ras gene; the parental NIH 3T3 cell line; or no DNA (a spontaneous transformant). Unlike the parental 3T3 cells, each of these lines readily formed malignant spindle cell tumors in Swiss nu/nu mice. Southern blots confirmed the presence of the human homologue of the Kirsten ras gene in the cells transformed by SW480 DNA, and the Harvey ras gene in the cells transformed with that cloned sequence. The morphology of each of the lines was different, the cells transformed with the human and viral ras genes being the most aberrant (but not identical) and forming the most extensive foci in culture. These ras transformed lines also exhibited anchorage-independent growth, while the two other transformed lines did not. Both of the ras transformed lines, as well as the spontaneously transformed line, exhibited a pronounced disruption of actin microfilament structure. Two-dimensional gel electrophoresis of ³⁵S-methionine-labeled peptides revealed that these three lines also had a marked decrease in an acidic peptide of 32K daltons.