Figure 2 | Cell Death & Disease

Figure 2

From: Celastrol targets proteostasis and acts synergistically with a heat-shock protein 90 inhibitor to kill human glioblastoma cells

Figure 2

Caspase-3 is dispensable for celastrol-mediated cell death in human glioblastoma cells. (a) U251N cells were incubated with either serum-containing (Serum+) or serum-deprived (Serum−) media or treated with 1 μM STS for 12 h or 3 μM celastrol for 24 h in serum-deprived media. Total cell lysates were collected and immunoblotted for PARP-1 cleavage, characteristic of caspase-3 activation. Actin is used as a control for protein loading. (b) U251N cells were treated with serum-deprived media with or without the caspase-3 selective inhibitor, Ac-DEVD-CMK, at the indicated concentrations for 3 h, after which celastrol was added at various concentrations (0.1–10 μM) for another 24 h. Cell viability was assessed by MTT assay. Caspase-3 inhibition led to a small but significant effect in shifting the dose–response to celastrol relative to treatment with celastrol alone (LD50: 1.12±0.19 μM with DEVD versus 1.45±0.28 μM with 20 μM DEVD and 1.35±0.14 μM with 50 μM DEVD; P=0.000113). Average values and S.Ds. are reported for triplicate measurements (N=3). Results are representative of at least three independent experiments

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