STAUROSPORINE BLOCKED NORMAL-CELLS AT G(1) S BOUNDARY/

AIM: To reveal the regulating difference of G(1)/S-phase transition be tween normal and tumor cells by using staurosporine, an unspecific kin ase inhibitor. METHODS: Flow cytometry, Dot blot, kinase activity assa y, and electrophoresis. RESULTS: A 18-h treatment with staurosporine ( 5 mu g . L(-1)) blocked normal cell line 2BS cells (normal human embry onic lung fibroblast, 5 - 20 passages) in G(1) phase, decreased their thymidine kinase (TK) mRNA level and activity, and also dephosphorylat ed an intracellular 107 kDa protein. Meanwhile, all these effects in 2 BS cells disappeared only by washing staurosporine away. Such kind of effects did not occur in tumor cell line BGC-823 cells (human stomach cancer cell). CONCLUSION: During the period of G(1)/S-phase transition , the kinases involved are more sensitive to staurosporine in normal c ells than in tumor cells.