Table 4.
Increased Toxicity of Paclitaxel in the Presence of Rationally Designed P-gp Inhibitorsa
inhibitor concentration | resensitization to paclitaxel with the indicated treatment and fold-increased sensitivity in the presence of inhibitors | ||||||||||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
PTX alone | PTX + 29 | PTX + 238 | PTX + 255 | PTX + 278 | PTX + 280 | PTX + 286 | |||||||||||||
IC50 PTX (nM) | IC50 PTX (nM) | fold vs PTX | fold vs PTX + 29 | IC50 PTX (nM) | fold vs PTX | fold vs PTX + 29 | IC50 PTX (nM) | fold vs PTX | fold vs PTX + 29 | IC50 PTX (nM) | fold vs PTX | fold vs PTX + 29 | IC50 PTX (nM) | fold vs PTX | fold vs PTX + 29 | IC50 PTX (nM) | fold vs PTX | fold vs PTX + 29 | |
3 μM | 2120 | 629 | 3 | 1 | 185 | 11 | 3.4 | 172 | 12 | 3.7 | 231 | 9.2 | 2.7 | 160 | 13 | 3.9 | 458 | 4.6 | 1.4 |
5 μM | 2120 | 194 | 11 | 1 | 1.9 | 1116 | 102 | 34 | 372 | 5.7 | 109 | 19 | 1.8 | 56 | 38 | 3.5 | 379 | 5.6 | 0.5 |
7 μM | 2120 | 59 | 36 | 1 | 0.64 | 3312 | 92 | 2.9 | 731 | 20 | 21 | 101 | 2.8 | 16 | 133 | 3.7 | 192 | 11 | 0.3 |
10 μM | 2120 | 21 | 101 | 1 | 0.07 | 30,286 | 300 | 0.78 | 2118 | 27 | 13 | 163 | 1.6 | 11 | 193 | 1.9 | 131 | 16 | 0.2 |
Cytotoxicity of the chemotherapeutic paclitaxel (PTX) in P-gp-overexpressing prostate cancer cells, DU145TXR, was determined in the absence and presence of the structural 29-variants, 238, 255, 276, 280, and 286. For each experimental compound, (a) IC 50 values of PTX alone or in the presence of inhibitors (in nM), (b) fold improvement of PTX sensitivity in the presence of an inhibitor, and (c) fold improvement of PTX sensitivity by variants compared to parental compound 29 are given.