title: Interaction of CJZ3, a lomerizine derivative, with ATPase activity of human P-glycoprotein in doxorubicin-resistant human myelogenous leukemia (K562/DOX) cells.
abstract: P-Glycoprotein, a 170-180 kDa membrane glycoprotein that mediates multidrug resistance, hydrolyses ATP to efflux a broad spectrum of hydrophobic agents. To observe the interaction of a P-gp reversal agent with P-gp ATPase activity should provide further insights into the mechanisms of P-gp modulator. In this study, we analysed the effect of CJZ3, a lomerizine derivative, on the adenosine triphosphatase (ATPase) activity of human P-glycoprotein. The results showed that the basal P-gp ATPase activity was increased by CJZ3 with half-maximal activity concentration (Km) of 6.8 +/- 1.5 microM, CJZ3 may interact with P-gp with a higher affinity and exhibit a more potent effect than verapamil (Ver). Kinetic analysis indicated a noncompetitive inhibition of Ver-stimulated P-gp ATPase activity and a competitive inhibition of CJX2-stimulated P-gp ATPase activity by CJZ3, moreover, the effect of CsA on CJZ3-stimulated and Ver-stimulated P-gp ATPase activity showed a non-competitive and a competitive inhibition respectively. CJZ3 and CJX2 can bind P-gp either on overlapping sites or distinct but interacting sites, while CJZ3 and Ver as well as CsA can bind P-gp on separated sites in K562/DOX cells.
authors.affiliation: Key Laboratory of Natural Medicine and Immune Engineering, Henan University, Kaiferng, PR China. jibianshengheling@yahoo.com.cn
authors.forename: Bian-Sheng
authors.initials: BS
authors.lastname: Ji
authors.forename: Ming
authors.initials: M
authors.lastname: Li
authors.forename: Ling
authors.initials: L
authors.lastname: He
mesh_terms: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1 / Q000378:metabolism*; D000251:Adenosine Triphosphatases / Q000378:metabolism*; D000903:Antibiotics, Antineoplastic / Q000494:pharmacology*; D002121:Calcium Channel Blockers / Q000494:pharmacology*; D002470:Cell Survival / Q000187:drug effects; D004317:Doxorubicin / Q000494:pharmacology*; D019008:Drug Resistance, Neoplasm; D006207:Half-Life; D006801:Humans; D020014:K562 Cells; D007700:Kinetics; D010879:Piperazines / Q000494:pharmacology*
chemical_list: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D000903:Antibiotics, Antineoplastic; D002121:Calcium Channel Blockers; D010879:Piperazines; D004317:Doxorubicin; C052424:lomerizine; D000251:Adenosine Triphosphatases