Staurosporine blocked normal cells at G1/S boundary.

AIM

To reveal the regulating difference of G1/S-phase transition between normal and tumor cells by using staurosporine, an unspecific kinase inhibitor.

METHODS

Flow cytometry, Dot blot, kinase activity assay, and electrophoresis.

RESULTS

A 18-h treatment with staurosporine (5 micrograms.L-1) blocked normal cell line 2BS cells (normal human embryonic lung fibroblast, 5-20 passages) in G1 phase, decreased their thymidine kinase (TK) mRNA level and activity, and also dephosphorylated an intracellular 107 kDa protein. Meanwhile, all these effects in 2BS 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 G1/S-phase transition, the kinases involved are more sensitive to staurosporine in normal cells than in tumor cells.