Reconstitution of the Antitumor Activity of pMC540
| Drugs . | Caspase 8 (fold increase) . | Caspase 3 (fold increase) . | Apo. (%) . | ||
|---|---|---|---|---|---|
| 12 h . | 18 h . | 12 h . | 18 h . | ||
| pMC540 (150 μg/mL) | 2.6 | 1.4 | 3 | 1.5 | 40 |
| C1 (25 μg/mL) | 1 | 1.8 | 1 | 1 | 10 |
| C2 (25 μg/mL) | 2.5 | 2.8 | 1.5 | 1.8 | 28* |
| C5 (100 μg/mL) | 1 | 2.1 | 1.23 | 1 | 15 |
| C1 + C2 | 3 | 4.5 | 4 | 2 | 40* |
| C1 + C5 | 1.3 | 2.5 | 1.5 | 1 | 15 |
| C2 + C5 | 2.6 | 4.6 | 3 | 2 | 38* |
| C1 + C2 + C5 | 6 | 4.5 | 7 | 1.5 | 50* |
| Drugs . | Caspase 8 (fold increase) . | Caspase 3 (fold increase) . | Apo. (%) . | ||
|---|---|---|---|---|---|
| 12 h . | 18 h . | 12 h . | 18 h . | ||
| pMC540 (150 μg/mL) | 2.6 | 1.4 | 3 | 1.5 | 40 |
| C1 (25 μg/mL) | 1 | 1.8 | 1 | 1 | 10 |
| C2 (25 μg/mL) | 2.5 | 2.8 | 1.5 | 1.8 | 28* |
| C5 (100 μg/mL) | 1 | 2.1 | 1.23 | 1 | 15 |
| C1 + C2 | 3 | 4.5 | 4 | 2 | 40* |
| C1 + C5 | 1.3 | 2.5 | 1.5 | 1 | 15 |
| C2 + C5 | 2.6 | 4.6 | 3 | 2 | 38* |
| C1 + C2 + C5 | 6 | 4.5 | 7 | 1.5 | 50* |
HL60 cells (1 × 106/mL) were incubated with pMC540, C1, C2, or C5 at the indicated concentrations or combinations of C1 (25 μg/mL) and C2 (25 μg/mL) and C5 (100 μg/mL) for 12 and 18 hours. Caspase 8 and 3 activities were determined by fluorimetric assays as described in Materials and Methods. Data are represented as fold increase in caspase activity over the baseline obtained with untreated cells (1×). The percentage of cell death was determined by the MTT assay 18 hours after drug treatment. Data shown are the mean of three independent observations.
C2 is the most potent of the purified compounds and explains most of the antitumor activity of pMC540.