Novel Non‐tumorigenic Cell Variants Showing Potentially Different Susceptibility to v‐src‐induced Metastasis

Two non‐tumorigenic variant cells were isolated from UV‐irradiated Balb/c 3T3 cells on the basis of their different responsiveness in phorbol ester‐induced morphological change (rounding formation). They showed marked differences of lung metastatic potentials after intravenous injections of their v‐src transformants into nude mice; phorbol ester‐resistant variant TR4 cells transformed by v‐src were hypermetastatic, whereas v‐src transformants of phorbol ester‐sensitive variant TR5 cells were not metastatic at all. These different metastatic responses were not observed in v‐K‐ras‐induced transformants of the variants. These non‐tumorigenic variant cells may pre‐acquire the genetic alteration of certain src‐specific and metastasis‐associated factors. This system may be useful for genetic analysis of the induction of metastasis.