title: Death receptor 5 promoter-enhancing compounds isolated from Catimbium speciosum and their enhancement effect on TRAIL-induced apoptosis.
abstract: The TRAIL/death-receptor signaling pathway has been considered a promising target for selective cancer therapy, although some malignant tumors exhibit TRAIL resistance. We previously found that isoflavonoid enhanced TRAIL-induced apoptosis in TRAIL-resistant cells, which is achieved through up-regulation of death receptor 5 (DR5). In our screening program targeting DR5 promoter enhancement activity, activity-guided fractionations of the extract of Catimbium speciosum led to the isolation of six compounds. Of the isolates, cardamomin (6), the most potent compound, enhanced the expressions of DR5 and DR4 and decreased the Bcl-xL level in TRAIL-resistant DLD1 cells. The combination of 6 and TRAIL synergistically enhanced TRAIL-induced apoptosis against TRAIL-resistant cells upon the activation of caspase-8, 9, and 3. In addition, enhancement of apoptosis by 6 was inhibited by human recombinant DR5/Fc and DR4/Fc chimera proteins, TRAIL-neutralizing fusion proteins, indicating that 6 sensitize TRAIL-resistant cells to TRAIL through the induction of DR5 and DR4. Also, up-regulation of DR5 by 6 paralleled that of CCAAT/enhancer-binding protein-homologous protein (CHOP).
authors.affiliation: Graduate School of Pharmaceutical Sciences, Chiba University, 1-33 Yayoi-cho, Inage-ku, Chiba 263-8522, Japan.
authors.forename: Takashi
authors.initials: T
authors.lastname: Ohtsuki
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Kikuchi
authors.forename: Takashi
authors.initials: T
authors.lastname: Koyano
authors.forename: Thaworn
authors.initials: T
authors.lastname: Kowithayakorn
authors.forename: Toshiyuki
authors.initials: T
authors.lastname: Sakai
authors.forename: Masami
authors.initials: M
authors.lastname: Ishibashi
mesh_terms: D032429:Alpinia / Q000737:chemistry*; D017209:Apoptosis / Q000187:drug effects*; D045744:Cell Line, Tumor; D047188:Chalcones / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology*; D006801:Humans; D015394:Molecular Structure; D010936:Plant Extracts / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology; D011401:Promoter Regions, Genetic / Q000187:drug effects*; D053220:Receptors, TNF-Related Apoptosis-Inducing Ligand / Q000235:genetics / Q000378:metabolism*; D027343:Rhizome / Q000737:chemistry; D053221:TNF-Related Apoptosis-Inducing Ligand / Q000378:metabolism*; D015854:Up-Regulation / Q000187:drug effects
chemical_list: D047188:Chalcones; D010936:Plant Extracts; D053220:Receptors, TNF-Related Apoptosis-Inducing Ligand; D053221:TNF-Related Apoptosis-Inducing Ligand; C436747:cardamonin