Celastraceae Sesquiterpenes as a New Class of Modulators That Bind Specifically to Human P-Glycoprotein and Reverse Cellular Multidrug Resistance

Abstract

Overexpression of ABCB1 (MDR1) P-glycoprotein, a multidrug efflux pump, is one mechanism by which tumor cells may develop multidrug resistance (MDR), preventing the successful chemotherapeutic treatment of cancer. Sesquiterpenes from Celastraceae family are natural compounds shown previously to reverse MDR in several human cancer cell lines and Leishmania strains. However, their molecular mechanism of reversion has not been characterized. In the present work, we have studied the ability of 28 dihydro-␤-agarofuran sesquiterpenes to reverse the P-glycoprotein-dependent MDR phenotype and elucidated their molecular mechanism of action. Cytotoxicity assays using human MDR1-transfected NIH-3T3 cells allowed us to select the most potent sesquiterpenes reversing the in vitro resistance to daunomycin and vinblastine. Flow cytometry experiments showed that the above active compounds specifically inhibited drug transport activity of P-glycoprotein in a saturable, concentration-dependent manner (K i down to 0.24 ؎ 0.01 mol/L) but not that of ABCC1 (multidrug resistance protein 1; MRP1), ABCC2 (MRP2), and ABCG2 (breast cancer resistance protein; BCRP) transporters. Moreover, sesquiterpenes inhibited at submicromolar concentrations the P-glycoprotein-mediated transport of [ 3 H]colchicine and tetramethylrosamine in plasma membrane from CH R B30 cells and P-glycoproteinenriched proteoliposomes, supporting that P-glycoprotein is their molecular target. Photoaffinity labeling in plasma membrane and fluorescence spectroscopy experiments with purified protein suggested that sesquiterpenes interact with transmembrane domains of P-glycoprotein. Finally, sesquiterpenes modulated P-glycoprotein ATPase-activity in a biphasic, concentration-dependent manner: they stimulated at very low concentrations but inhibited ATPase activity as noncompetitive inhibitors at higher concentrations. Sesquiterpenes from Celastraceae are promising P-glycoprotein modulators with potential applications in cancer chemotherapy because of their MDR reversal potency and specificity for P-glycoprotein.

Molluscicidal and Mosquitocidal Activities of the Essential oils of Thymus capitatus Hoff. et Link. and Marrubium vulgare L.

“…They may kill snails as well as snail egg masses via contact poisoning resulting in killing the early egg embryos 11 . These findings are in accordance with other studies that mentioned sesquiterpenes as promising skin penetration enhancers with specific P-glycoprotein modulators that can reverse cellular multidrug resistance by inhibiting the drug efflux process 26,34 . Other studies also stated that antimicrobial properties of essential oils from M. vulgare are associated with their high contents of oxygenated compounds (46.21%) 41 .…”

Cytotoxicity of Vincristine on the 5637 Cell Line Is Enhanced by Combination with Conferone

“…Conferone, the fi rst identifi ed natural sesquiterpene coumarin from Ferula, is a promising drug candidate for reversion of MDR encoded by the MDR1 gene (Barthomeuf et al, 2006). The capacity of conferone to bind P-gp with high affi nity is in agreement with the observation that a binding site for sesquiterpenes exists within the transmembrane domain of P-gp (Munoz-Martinez et al, 2004). In summary, as the main cause of failure of cancer therapy is related to inherent or acquired overexpression of effl ux pumps by tumour cells, the potency of sesquiterpenes, as blockers of P-gpmediated drug transport activity, would make these components suitable for entry into clinical studies.…”

“…Several studies have shown that some drimane-type sesquiterpene coumarins such as conferone, mogoltacin and diportlandian ( Fig. 1) can increase the drug accumulation and effectiveness by P-glycoprotein inhibition (Barthomeuf et al, 2006;Behnam Rassouli et al, 2009;Munoz-Martinez et al, 2004).…”

Leishmania: papel de la glicoproteína P en la mediación de resistencia a medicamentos y estrategias de reversión.

“…En un trabajo reciente, se estudiaron 28 sesquiterpenos capaces de revertir el fenotipo MDR dependiente de Pgp para elucidar su mecanismo molecular de acción (137). La investigación sugiere que los sesquiterpenos interactúan, principalmente, con los dominios transmembrana de Pgp y a altas concentraciones pueden actuar como inhibidores no competitivos de la actividad ATPasa (137).…”

“…La investigación sugiere que los sesquiterpenos interactúan, principalmente, con los dominios transmembrana de Pgp y a altas concentraciones pueden actuar como inhibidores no competitivos de la actividad ATPasa (137).…”