[Modulation of PKC inhibitor on growth cycle of human keratocyte]

To study the effects of staurosporine (ST), an inhibitor of protein kinase C (PKC), on the cell cycle of cultured human keratocyte at G(1)/S phase transition and to study the molecular mechanism of this process.

Flow cytometry technique was used to define the effect of ST on the cell cycle of cultured human keratocyte. Cyclin E protein levels of corneal keratocyte were analyzed by using the cyclin/DNA two parameter flow cytometry.

Treatment of ST (2.5 microg/L and 5 microg/L) for 18 hours blocked the growth of keratocyte in G(1) phase; the percentage of cells staying in G(1) phase was increased from 72.4% in the control group to 78.4% (group 2.5 microg/L ST) and 90.9% (group 5 microg/L ST), respectively. This effect was dose dependent. Cyclin E protein level in G(1) phase was decreased from 75.6% in the control group to 62.0% (group 2.5 microg/L ST) and 51.1% (group 5 microg/L ST) in cells treated with ST.

PKC activity is important in promoting keratocyte proliferation. Inhibition of PKC activity prohibits G(1)/S phase progress and reduces cyclin E protein level. Inhibitor of PKC is involved in the modulation of the cell cycle of human keratocyte and may play an important role in inhibiting cell growth in G(1)/S phase.