Chemical transformation of Chinese hamster cells. I. A comparison of some properties of transformed cells.

Fifty-one subclones from carcinogen-treated cells of 3 tissues (kidney, liver and prostate) of the male Chinese hamster have been studied to determine the relationships of 3 criteria of in vitro transformation: morphological change, increased plating efficiency and growth in soft agar. There was no correlation between increased plating efficiency and the other 2 parameters. Morphological change was not always easily recognisable, particularly in cells derived from liver, and was not always a stable feature of any given subclone. This may be due to the technique of isolation used (ring cloning) or may be due to chemically-treated cells requiring long periods of culturing before attaining a stable phenotype. When a stable morphological appearance was achieved, there was good correlation between transformed morphology and colony formation in soft agar. The problems of scoring morphological change as an assessment of malignant transformation, and the importance of spontaneous morphological changes are discussed.