title: (+/-)-3'-O, 4'-O-dicynnamoyl-cis-khellactone, a derivative of (+/-)-praeruptorin A, reverses P-glycoprotein mediated multidrug resistance in cancer cells.
abstract: P-glycoprotein (Pgp) is an ATP-driven membrane exporter for a broad spectrum of hydrophobic xenobiotics. Pgp-overexpression is a common cause of multidrug resistance (MDR) in cancer cells and could lead to chemotherapeutic failure. Through an extensive herbal drug screening program we previously showed that (+/-)-praeruptorin A (PA), a naturally existing pyranocumarin isolated from the dried root of Peucedanum praeruptorum Dunn., re-sensitizes Pgp-mediated MDR (Pgp-MDR) cancer cells to cancer drugs. A number of PA derivatives were synthesized and one of these, (+/-)-3'-O, 4'-O-dicynnamoyl-cis-khellactone (DCK), was more potent than PA or verapamil in the reversal of Pgp-MDR. In Pgp-MDR cells DCK increased cellular accumulation of doxorubicin without affecting the expression level of Pgp. In Pgp-enriched membrane fractions DCK moderately stimulated basal Pgp-ATPase activity, suggesting some transport substrate-like function. However, DCK also inhibited Pgp-ATPase activity stimulated by the standard substrates verapamil or progesterone with decreased V(max)s but K(m)s were relatively unchanged, suggesting a primarily non-competitive mode of inhibition. While the binding of substrates to active Pgp would increase the reactivity of the Pgp-specific antibody UIC2, DCK decreased UIC2 reactivity. These results suggest that DCK could bind simultaneously with substrates to Pgp but perhaps at an allosteric site and thus affect Pgp-substrate interactions.
authors.affiliation: Bioactive Products Research Group, Department of Biology and Chemistry, City University of Hong Kong, Hong Kong SAR, China.
authors.forename: Xiaoling
authors.initials: X
authors.lastname: Shen
authors.forename: Guangying
authors.initials: G
authors.lastname: Chen
authors.forename: Guoyuan
authors.initials: G
authors.lastname: Zhu
authors.forename: Wang-Fun
authors.initials: WF
authors.lastname: Fong
mesh_terms: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1 / Q000502:physiology*; D000251:Adenosine Triphosphatases / Q000378:metabolism; D000970:Antineoplastic Agents / Q000494:pharmacology; D015153:Blotting, Western; D002455:Cell Division / Q000187:drug effects; D045744:Cell Line, Tumor; D003374:Coumarins / Q000737:chemistry* / Q000494:pharmacology*; D004317:Doxorubicin / Q000494:pharmacology; D018432:Drug Resistance, Multiple / Q000502:physiology*; D019008:Drug Resistance, Neoplasm / Q000502:physiology*; D004357:Drug Synergism; D004789:Enzyme Activation; D016195:G2 Phase / Q000187:drug effects; D006801:Humans; D013379:Substrate Specificity
chemical_list: C515584:3'-O, 4'-O-dicynnamoyl-cis-khellactone; D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D000970:Antineoplastic Agents; D003374:Coumarins; C441070:praeruptorin A; D004317:Doxorubicin; D000251:Adenosine Triphosphatases