title: Stigmalactam from Orophea enterocarpa induces human cancer cell apoptosis via a mitochondrial pathway.
abstract: Stigmalactam, an aristolactam-type alkaloid extracted from Orophea enterocarpa, exerts cytotoxicity against several human and murine cancer cell lines, but the molecular mechanisms remain elusive. The aims of this study were to identify the mode and mechanisms of human cancer cell death induced by stigmalactam employing human hepatocellular carcinoma HepG2 and human invasive breast cancer MDA-MB-231 cells as models, compared to normal murine fibroblasts. It was found that stigmalactam was toxic to HepG2 and MDA-MB-231 cells with IC50 levels of 23.0±2.67 μM and 33.2±4.54 μM, respectively, using MTT assays. At the same time the IC50 level towards murine normal fibroblast NIH3T3 cells was 24.4±6.75 μM. Reactive oxygen species (ROS) production was reduced in stigmalactam-treated cells dose dependently after 4 h of incubation, indicating antioxidant activity, measured by using 2',7',-dichlorohydrofluorescein diacetate and flow cytometry. Caspase-3 and caspase-9 activities were increased in a dose response manner, while stigmalactam decreased the mitochondrial transmembrane potential dose-dependently in HepG2 cells, using 3,3'-dihexyloxacarbocyanine iodide and flow cytometry, indicating mitochondrial pathway-mediated apoptosis. In conclusion, stigmalactam from O. enterocarpa was toxic to both HepG2 and MDA-MB-231 cells and induced human cancer HepG2 cells to undergo apoptosis via the intrinsic (mitochondrial) pathway.
authors.affiliation: Dept of Biochemistry, Faculty of Medicine, Chiang Mai University, Chiang Mai, ThailandE-mail : rbanjerd@gmail.com.
authors.forename: Ratana
authors.initials: R
authors.lastname: Banjerdpongchai
authors.forename: Benjawan
authors.initials: B
authors.lastname: Wudtiwai
authors.forename: Wilart
authors.initials: W
authors.lastname: Pompimon
mesh_terms: D000818:Animals; D029061:Annonaceae; D017209:Apoptosis / Q000187:drug effects*; D001943:Breast Neoplasms / Q000378:metabolism*; D006528:Carcinoma, Hepatocellular / Q000378:metabolism*; D053148:Caspase 3 / Q000187:drug effects / Q000378:metabolism; D053453:Caspase 9 / Q000187:drug effects / Q000378:metabolism; D045744:Cell Line, Tumor; D005347:Fibroblasts / Q000378:metabolism; D056945:Hep G2 Cells; D006801:Humans; D008113:Liver Neoplasms / Q000378:metabolism*; D051379:Mice; D008928:Mitochondria / Q000187:drug effects* / Q000378:metabolism; D041681:NIH 3T3 Cells; D010616:Phenanthrenes / Q000494:pharmacology*; D017382:Reactive Oxygen Species
chemical_list: D010616:Phenanthrenes; D017382:Reactive Oxygen Species; C414695:stigmalactam; D053148:Caspase 3; D053453:Caspase 9