Effects of nicardipine and several noscapine derivatives on calcein-AM accumulation in drug-sensitive and -resistant breast cancer cell lines
Accumulation of calcein in NCI/AdrRES cells was determined from the rate of fluorescence change and plotted as a function of added drug concentration. A secondary plot was used to determine the potency of drugs (MP50) to alter the accumulation of calcein and the maximal rate (AMAX) for this accumulation. Parameters (mean ± S.E.M.) were obtained by nonlinear regression of a hyperbolic equation.
| Compound | (n) | Potency | Extent |
|---|---|---|---|
| MP50 | AMAX | ||
| μM | rfu | ||
| Nicardipine | (11) | 2.5 ± 0.6 | 110 ± 19 |
| Noscapine | (9) | 8.5 ± 2.1 | 24.6 ± 6.7 |
| (2) | — | nd | nd |
| (3) | — | nd | nd |
| (4) | (4) | 10.1 ± 2.7 | 145 ± 33* |
| (5) | (4) | NE | NE |
| (6) | (6) | 0.37 ± 0.07* | 35.1 ± 4.0 |
| (7) | (4) | NE | NE |
| (8) | (5) | 1.2 ± 0.2* | 137 ± 30* |
| (9) | (8) | 6.9 ± 2.0 | 67.6 ± 26.0 |
| (10) | (7) | 3.8 ± 1.0 | 76.3 ± 28.7 |
| (11) | (4) | 20.9 ± 5.3** | 83.5 ± 21.7 |
(n), Number of independent observations. NE, the compound did not alter calcein-AM accumulation; and n.d., no values were determined; rfu, relative fluorescence units.
* Statistically significant difference (P < 0.05) compared with the value for noscapine.
** P < 0.01.