title: Pseudolaric acid B induces apoptosis via proteasome-mediated Bcl-2 degradation in hormone-refractory prostate cancer DU145 cells.
abstract: Pseudolaric acid B (PAB), a natural diterpene acid present in the traditional Chinese medicinal herb Tu-Jin-Pi, exerted anticancer effects on various cancer cells. However, the effect of PAB on DU145 cells, an in vitro model of hormone-refractory prostate cancer (HRPC), has not been reported previously. In the study, PAB significantly suppressed proliferation of DU145 cells in a dose-dependent manner without obvious cytotoxicity. IC(50) values of 0.89 ± 0.18 and 0.76 ± 0.15 μM at 48h was determined by Cell counting kit (CCK-8) assay and clone formation assay, respectively. PAB also induced DU145 cells apoptosis as confirmed by typical morphological changes and Annexin V-FITC staining. Furthermore, we demonstrated that PAB caused a concentration-dependent elevation of reactive oxygen species (ROS) level in DU145 cells, and N-acetyl-l-cysteine (NAC, a well-known ROS scavenger) could block PAB-induced ROS generation and apoptosis. Western blotting and/or caspase activity data indicated that PAB downregulated anti-apoptotic Bcl-2 protein and activated caspase-9 and caspase-3, which were largely rescued by NAC or MG-132 (proteasome inhibitor). Taken together, these findings provide the first evidence that PAB may inhibit growth of HRPC DU145 cells and induce apoptosis through ROS generation and Bcl-2 degradation via the activation of the ubiquitin-proteasome pathway.
authors.affiliation: Department of Biochemistry and Molecular Biology, College of Basic Medical Science, Harbin Medical University, 194, Xue Fu Road, Nan Gang District, Harbin 150081, PR China. zhao_dan_dan@yahoo.com.cn
authors.forename: Dandan
authors.initials: D
authors.lastname: Zhao
authors.forename: Feng
authors.initials: F
authors.lastname: Lin
authors.forename: Xingde
authors.initials: X
authors.lastname: Wu
authors.forename: Qinshi
authors.initials: Q
authors.lastname: Zhao
authors.forename: Binjiahui
authors.initials: B
authors.lastname: Zhao
authors.forename: Ping
authors.initials: P
authors.lastname: Lin
authors.forename: Yanlong
authors.initials: Y
authors.lastname: Zhang
authors.forename: Xiaoguang
authors.initials: X
authors.lastname: Yu
mesh_terms: D017209:Apoptosis / Q000187:drug effects; D053148:Caspase 3 / Q000378:metabolism; D053453:Caspase 9 / Q000378:metabolism; D045744:Cell Line, Tumor; D002470:Cell Survival / Q000187:drug effects; D054697:Cytostatic Agents / Q000494:pharmacology*; D004224:Diterpenes / Q000494:pharmacology*; D004365:Drugs, Chinese Herbal / Q000494:pharmacology*; D006801:Humans; D007770:L-Lactate Dehydrogenase / Q000378:metabolism; D008297:Male; D011471:Prostatic Neoplasms / Q000378:metabolism; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000378:metabolism*; D017382:Reactive Oxygen Species / Q000378:metabolism
chemical_list: D054697:Cytostatic Agents; D004224:Diterpenes; D004365:Drugs, Chinese Herbal; D019253:Proto-Oncogene Proteins c-bcl-2; D017382:Reactive Oxygen Species; C058391:pseudolaric acid B; D007770:L-Lactate Dehydrogenase; D053148:Caspase 3; D053453:Caspase 9