pgp - publications
Avermectin induces P-glycoprotein expression in S2 cells via the calcium/calmodulin/NF-κB pathway.
Chem Biol Interact. 2013 Mar 21;
Authors: Luo L, Sun YJ, Yang L, Huang S, Wu YJ
Avermectin (AVM) is a macrocyclic lactone agent widely used as a nematicide, acaricide and insecticide in veterinary medicine. P-glycoprotein (P-gp) is an ATP-dependent drug efflux pump for xenobiotic compounds, and is involved in multidrug resistance. To understand the development of AVM resistance in invertebrates, we investigated the mechanisms by which AVM affected P-gp expression in Drosophila S2 cells. We found that AVM induced upregulation of P-gp protein expression, increased P-gp ATPase activity and enhanced cellular efflux of the P-gp substrate rhodamine 123 from cells. Furthermore, we observed that AVM-induced expression of P-gp was due to elevation of intracellular calcium concentration ([Ca(2+)]i). This occurred both directly, by activating calcium ion channels, and indirectly, by activating chloride ion channels. These results are supported by our observations that verapamil, a Ca(2+) channel blocker, and niflumic acid, a chloride channel antagonist, significantly attenuated AVM-induced [Ca(2+)]i elevation, thereby reducing P-gp expression. Inhibition of P-gp with anti-P-gp antibody or cyclosporine A (a P-gp inhibitor) reduced the AVM-induced elevation of [Ca(2+)]i, implying that P-gp and [Ca(2+)]i regulate each other. Finally, we found that trifluoperazine, a calmodulin inhibitor, and pyrrolidine dithiocarbamic acid, an NF-κB inhibitor, attenuated the AVM-induced expression of P-gp, suggesting that AVM induces P-gp protein expression via the calmodulin and Relish (NF-κB) signaling pathways.
PMID: 23523950 [PubMed - as supplied by publisher]