demecolcine and Astrocytoma

The parallel effects of simvastatin on cell cycle and PKC activity in rat C6 glioma cells were investigated. Simvastatin, 2.5 microM, for 24 h resulted in cell growth arrest in early G1 phase of the cell cycle and in a significant increase of total PKC activity (283 +/- 42 vs 470 +/- 61 pmoles/min/mg protein p = 0.002 for control cells and simvastatin-treated cells, respectively). The effect of simvastatin was fully prevented by mevalonate. A time dependent increase of PKC activity was observed in control exponentially free-growing C6 cells approaching confluency: a highly significant negative correlation (r = -0.91 p < 0.0001) between PKC activity and growth rate was calculated. PKC activity was high in cells arrested in G0 by serum starvation (0.4%). Following addition of complete medium (17.5% serum) the PKC activity progressively decreased and reached a minimum when cells traversed the G2/M phase, as determined by DNA analysis distribution. PKC activity dropped 30% in simvastatin-arrested early G1 cells; 44% in hydroxyurea-arrested cells at the G1/S boundary; and 73% in Colcemid mitosis-blocked cells. The results show that C6 glioma cell PKC activity is maximal in a G0 quiescent state and varies at different points of the cell cycle.

Topics: Animals; Astrocytoma; Cell Cycle; Demecolcine; Glioma; Hydroxymethylglutaryl-CoA Reductase Inhibitors; Hydroxyurea; Lovastatin; Mevalonic Acid; Protein Kinase C; Rats; Simvastatin; Tumor Cells, Cultured

Topics: Astrocytes; Astrocytoma; Cell Differentiation; Cell Movement; Cells, Cultured; Cytoskeleton; Demecolcine; Glial Fibrillary Acidic Protein; Humans; Mitosis; Nerve Tissue Proteins