Table 1. Effects of gemcitabine, topotecan or their combinations on cell proliferation, caspase activity and apoptosis in A549 and Calu-6 cells. Data are the mean±s.e. from three independent experiments.
| Treatment | Cells | IC50 (ng ml−1)a | Apoptotic indexb | Caspase activity (pmol min−1 mg−1)c |
|---|---|---|---|---|
| Control | A549 | / | 4.3±0.6% | 0.12±0.08 |
| Calu-6 | / | 3.1±0.3% | 0.10±0.06 | |
| Topotecan | A549 | 840.2±121.2 | 7.7±1.4% | 0.32±0.11 |
| Calu-6 | 562.3±93.5 | 6.1±0.4% | 0.39±0.13 | |
| Gemcitabine | A549 | 131.2±30.3 | 13.4±4.6% | 0.86±0.14 |
| Calu-6 | 1662.4±360.6 | 8.6±2.0 | 0.69±0.25 | |
| Gemcitabine → topotecan | A549 | 620.1±104.1 | 10.5±0.7% | 1.07±0.12 |
| Calu-6 | 2063.8±414.6 | 11.5±2.8% | 0.94±0.31 | |
| Gemcitabine+topotecan | A549 | 12.4±1.4 | 34.0±3.6% | 2.76±0.10 |
| Calu-6 | 40.4±4.76 | 27.6±3.6% | 2.55±0.37 | |
| Topotecan → gemcitabine | A549 | 6.3±0.3 | 29.2±5.9% | 1.43±0.11 |
| Calu-6 | 179.5±38.7 | 19.8±3.2% | 1.55±0.28 |
a
50% inhibitory concentrations of cell growth.
b
Percentage ratio between the number of cells displaying apoptotic appearance and the total number of counted cells.
c
Enzyme activity is normalised with respect to total protein content of each cell extract.