ABSTRACT
OC144-093 is a novel substituted diarylimidazole (Mr 495) generated using the OntoBLOCK system, a solid-phase combinatorial chemistry technology, in combination with high-throughput cell-based screening. OC144-093 reversed multidrug resistance (MDR) to doxorubicin, paclitaxel, and vinblastine in human lymphoma, breast, ovarian, uterine, and colorectal carcinoma cell lines expressing P-glycoprotein (P-gp) with an average EC50 of 0.032 microM. Inhibition of MDR by OC144-093 was reversible, but the effect persisted for at least 12 h after removal of compound from the culture medium. OC144-093 had no effect on the response to cytotoxic agents by cells in vitro lacking P-gp expression or expressing a multidrug resistance-associated protein (MRP-1). OC144-093 was not cytotoxic by itself against 15 normal, nontransformed, or tumor cell lines, regardless of P-gp status, with an average cytostatic IC50 of >60 microM. OC144-093 blocked the binding of [3H]azidopine to P-gp and inhibited P-gp ATPase activity. The compound was >50% p.o. bioavailable in rodents and dogs and did not alter the plasma pharmacokinetics of i.v.-administered paclitaxel. OC144-093 increased the life span of doxorubicin-treated mice engrafted with MDR P388 leukemia cells by >100% and significantly enhanced the in vivo antitumor activity of paclitaxel in MDR human breast and colon carcinoma xenograft models, without a significant increase in doxorubicin or paclitaxel toxicity. The results demonstrate that OC144-093 is an orally active, potent, and nontoxic inhibitor of P-gp-mediated multidrug resistance that exhibits all of the desired properties for treatment of P-gp-mediated MDR, as well as for prevention of MDR prior to selection and/or induction of refractory disease.
Subject(s)
ATP Binding Cassette Transporter, Subfamily B, Member 1/antagonists & inhibitors , Drug Resistance, Multiple , Imidazoles/pharmacology , Adenosine Triphosphatases/metabolism , Animals , Antineoplastic Agents/pharmacology , Antineoplastic Agents, Phytogenic/pharmacology , Cell Division/drug effects , Dogs , Dose-Response Relationship, Drug , Doxorubicin/pharmacology , Drug Resistance, Neoplasm , Female , Humans , Imidazoles/chemistry , Inhibitory Concentration 50 , Kinetics , Mice , Mice, SCID , Paclitaxel/pharmacology , Rats , Time Factors , Tumor Cells, Cultured , Vinblastine/pharmacologyABSTRACT
Analogues of tricyclic antidepressants were synthesized in which the alpha-carbon of the side chain was replaced by nitrogen. The antidepressant activity of these imines, as measured by the reversal of the effects of tetrabenazine in mice, showed a structure-activity relationship similar to that of the carbon analogues. The most active imine (19) was six times as potent as amitriptyline. Some of the compounds differed from amitriptyline in that they produced stimulation in mice.
