The effectiveness of chemotherapeutic treatment is usually limited by the overexpression of
adenosine triphosphate binding cassette (
ABC) transporters, which mediate multidrug resistance (MDR) by acting as efflux pumps to remove chemotherapeutic agents from MDR
cancer cells. Thus, the inhibition of
ABC transporters may represent a promising strategy to reverse MDR. This study was to characterize the actions of
FG020326, a newly synthesized triaryl-substituted
imidazole derivative, to reverse MDR in vitro and in vivo.
FG020326 significantly potentiated the cytotoxicity of
paclitaxel,
doxorubicin, and
vincristine in the ABCB1 (
P-glycoprotein, P-gp) overexpressing cells KBv200 and MCF-7/adr, but not in the ABCB1 negative parental cell lines KB and MCF-7. However,
FG020326 did not alter the cytotoxicity of the aforementioned drugs in ABCC1 (
MRP1), ABCC4 (MRP4), ABCG2 (BCRP) and LRP overexpressing cell lines, KB-CV60, NIH3T3/MRP4-2, S1-M1-80 and SW1573/2R120, respectively.
FG020326, following p.o. administration, was present in concentrations sufficient for reversal of MDR in mice. The co-administration of
FG020326 with
paclitaxel or
vincristine significantly enhanced the antitumor activity of these drugs without significantly increasing toxicity in the mice bearing the KBv200 cell xenografts. In addition,
FG020326, at concentrations that reversed MDR, did not significantly affect the activity of
CYP3A4 or alter the pharmacokinetic profile of
paclitaxel after co-administration with
paclitaxel.
FG020326 produced a significant concentration-dependent displacement of [3H]
azidopine and inhibition of efflux of
drug from cells. Furthermore,
FG020326 was co-localized with ABCB1 in cell membranes. Hence,
FG020326 is characterized as a third generation MDR modulator that holds great promise for the treatment of
cancer patients with ABCB1-mediated MDR.