title: Flavokawain B, a kava chalcone, induces apoptosis via up-regulation of death-receptor 5 and Bim expression in androgen receptor negative, hormonal refractory prostate cancer cell lines and reduces tumor growth.
abstract: Limited success has been achieved in extending the survival of patients with metastatic and hormone-refractory prostate cancer (HRPC). There is a strong need for novel agents in the treatment and prevention of HRPC. We have shown that flavokawain B (FKB), a kava chalcone, is about 4- to 12-fold more effective in reducing the cell viabilities of androgen receptor (AR)-negative, HRPC cell lines DU145 and PC-3 than AR-positive, hormone-sensitive prostate cancer cell lines LAPC4 and LNCaP, with minimal effect on normal prostatic epithelial and stromal cells. FKB induces apoptosis with an associated increased expression of proapoptotic proteins: death receptor-5, Bim and Puma and a decreased expression of inhibitors of apoptosis protein: XIAP and survivin. Among them, Bim expression was significantly induced by FKB as early as 4 hr of the treatment. Knockdown of Bim expression by short-hairpin RNAs attenuates the inhibitory effect on anchorage-dependent and -independent growth and caspase cleavages induced by FKB. These findings suggest that the effect of FKB, at least in part, requires Bim expression. In addition, FKB synergizes with TRAIL for markedly enhanced induction of apoptosis. Furthermore, FKB treatment of mice bearing DU145 xenograft tumors results in tumor growth inhibition and increases Bim expression in tumor tissues. Together, these results suggest robust mechanisms for FKB induction of apoptosis preferentially for HRPC and the potential usefulness of FKB for prevention and treatment of HRPC in an adjuvant setting.
authors.affiliation: Department of Urology, University of California, Irvine, Orange, CA 92868, USA.
authors.forename: Yaxiong
authors.initials: Y
authors.lastname: Tang
authors.forename: Xuesen
authors.initials: X
authors.lastname: Li
authors.forename: Zhongbo
authors.initials: Z
authors.lastname: Liu
authors.forename: Anne R
authors.initials: AR
authors.lastname: Simoneau
authors.forename: Jun
authors.initials: J
authors.lastname: Xie
authors.forename: Xiaolin
authors.initials: X
authors.lastname: Zi
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000187:drug effects*; D051017:Apoptosis Regulatory Proteins / Q000235:genetics / Q000378:metabolism*; D000072224:Bcl-2-Like Protein 11; D015153:Blotting, Western; D049109:Cell Proliferation; D004797:Enzyme-Linked Immunosorbent Assay; D005419:Flavonoids / Q000494:pharmacology*; D006801:Humans; D047468:Immunoprecipitation; D008297:Male; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D011471:Prostatic Neoplasms / Q000188:drug therapy / Q000378:metabolism* / Q000473:pathology*; D011518:Proto-Oncogene Proteins / Q000235:genetics / Q000378:metabolism*; D012333:RNA, Messenger / Q000235:genetics; D011944:Receptors, Androgen / Q000235:genetics / Q000378:metabolism*; D053220:Receptors, TNF-Related Apoptosis-Inducing Ligand / Q000235:genetics / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014407:Tumor Cells, Cultured
chemical_list: C410798:AR protein, human; D051017:Apoptosis Regulatory Proteins; C000606775:BCL2L11 protein, human; D000072224:Bcl-2-Like Protein 11; C000606776:Bcl2l11 protein, mouse; D005419:Flavonoids; D008565:Membrane Proteins; D011518:Proto-Oncogene Proteins; D012333:RNA, Messenger; D011944:Receptors, Androgen; D053220:Receptors, TNF-Related Apoptosis-Inducing Ligand; C452039:flavokawain B