TABLE 2

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)PotencyExtent
MP50AMAX
μMrfu
Nicardipine(11)2.5 ± 0.6110 ± 19
Noscapine(9)8.5 ± 2.124.6 ± 6.7
(2)ndnd
(3)ndnd
(4)(4)10.1 ± 2.7145 ± 33*
(5)(4)NENE
(6)(6)0.37 ± 0.07*35.1 ± 4.0
(7)(4)NENE
(8)(5)1.2 ± 0.2*137 ± 30*
(9)(8)6.9 ± 2.067.6 ± 26.0
(10)(7)3.8 ± 1.076.3 ± 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.