TABLE 2

Calpain and cathepsin inhibitors are ineffective, whereas the natural proteasome inhibitor epoxomicin is highly effective in potentiating Eto-induced cell death in ADF cells

Human astrocytoma ADF cells were grown under control conditions or in the presence of either Eto alone or in combination with various pharmacological agents. At the end of the incubation period, the percentage of apoptotic death was evaluated by flow cytometric analysis of PI-stained nuclei. Epoxomicin was not toxic per se up to a 10 μM concentration (percentage of cell death: 3.35 ± 0.74%, P = 0.08 with respect to control; one-way ANOVA, Scheffé F test). Results represent the means ± S.E.M. of three independent experiments.

	Apoptotic Death
	%
Control (18 h)	1.18 ± 0.33
Eto, 100 μM	9.53 ± 0.95^a
+ E64, 50 μM	8.82 ± 0.67^a
+ Pepstatin, 10 μM	7.96 ± 1.96^a
+ Ca-074Me, 50 μM	9.65 ± 0.35^a
+ Epoxomicin, 1 μM	48.39 ± 0.87^b
Control (24 h)	1.65 ± 0.75
Eto, 100 μM	16.03 ± 5.02^a
+ Calpastatin, 10 μM	16.84 ± 5.34^a

↵ a P < 0.05 with respect to corresponding control.
↵ b P < 0.05 with respect to corresponding control and Eto alone; one-way ANOVA (Scheffé F test).