High-level expression of human c-Src can cause a spherical morphology without loss of anchorage-dependent growth of NIH 3T3 cells

To investigate whether overexpression of human c-Src leads to cell rounding in anchorage-dependent NIH3T3 fibroblasts, we have established c-Src-inducible cell lines using a lac repressor-operator system, RN1 cells, which expressed c-Src at a high level after induction, exhibited a spherical morphology and ceased to grow in monolayer culture, RN1 cells, however, exhibited neither focus-forming ability nor anchorage-independent growth potential with or without induction, Induced RN1 c-Src was phosphorylated at Ser(75) a previously reported spherical cell-associated site, and at Tyr(419). These data demonstrated for the first time that highly elevated human c-Src tyrosine kinase activity can cause NIH 3T3 cells to have a spherical morphology without loss of anchorage-dependent growth. The inducible cell line should be useful to study the mechanism for cell rounding by c-Src. (C) 1997 Federation of European Biochemical Societies.