title: Casearin X exhibits cytotoxic effects in leukemia cells triggered by apoptosis.
abstract: Clerodane diterpenes have demonstrated cytotoxic, antiplasmodial and anti-ulcer properties. In the present work, we determined the cytotoxic effect of casearin L (Cas L), O (Cas O) and X (Cas X) and (-)-hardwickiic acid isolated from Casearia sylvestris leaves, and investigated the underlying mechanisms involved in in vitro cell death induced by Cas X in HL-60 leukemia cells (0.7, 1.5 and 3.0μM). Cytotoxicity tests demonstrated that Cas X was the most active compound studied, showing greater cytotoxic effects against CEM and HL-60 lines (IC(50) of 0.4μM) and human peripheral blood mononuclear cells (PBMC, IC(50) of 1.2μM). After 24h exposure, Cas X caused a decrease in 5-bromo-20-deoxyuridine (BrdU) incorporation (36.6 and 24.5% labeling at 0.7 and 1.5μM, respectively), reduction in viability, and increase in apoptotic and necrotic leukemia cells in a dose-dependent manner evidenced by the trypan blue and AO/EB (acridine orange/ethidium bromide) assays. Moreover, Cas X-treated cells exhibited nuclear fragmentation and cytoplasmic vacuolization depending on the concentration tested. These characteristics of apoptosis or secondary necrosis were confirmed by flow cytometry which revealed DNA fragmentation, phosphatidylserine externalization, activation of the effector caspases 3/7 and mitochondrial depolarization. We then found evidence that Cas X causes cell death via apoptotic pathways, corroborating the potential of casearins as compounds with promising antitumor-related properties.
authors.affiliation: Universidade Federal do Piauí, 64.600-000 Picos, Piauí, Brazil.
authors.forename: Paulo M Pinheiro
authors.initials: PM
authors.lastname: Ferreira
authors.forename: André G
authors.initials: AG
authors.lastname: Santos
authors.forename: Aristeu G
authors.initials: AG
authors.lastname: Tininis
authors.forename: Patricia M
authors.initials: PM
authors.lastname: Costa
authors.forename: Alberto J
authors.initials: AJ
authors.lastname: Cavalheiro
authors.forename: Vanderlan S
authors.initials: VS
authors.lastname: Bolzani
authors.forename: Manoel O
authors.initials: MO
authors.lastname: Moraes
authors.forename: Letícia V
authors.initials: LV
authors.lastname: Costa-Lotufo
authors.forename: Raquel C
authors.initials: RC
authors.lastname: Montenegro
authors.forename: Cláudia
authors.initials: C
authors.lastname: Pessoa
mesh_terms: D017209:Apoptosis / Q000187:drug effects*; D053148:Caspase 3 / Q000378:metabolism; D053179:Caspase 7 / Q000378:metabolism; D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism; D002470:Cell Survival / Q000187:drug effects; D004247:DNA / Q000096:biosynthesis / Q000235:genetics; D053938:DNA Fragmentation / Q000187:drug effects; D004224:Diterpenes / Q000494:pharmacology; D045785:Diterpenes, Clerodane / Q000494:pharmacology*; D004789:Enzyme Activation / Q000187:drug effects; D005434:Flow Cytometry; D018922:HL-60 Cells; D006801:Humans; D007938:Leukemia / Q000473:pathology*; D008928:Mitochondria / Q000187:drug effects; D010718:Phosphatidylserines / Q000378:metabolism
chemical_list: C548433:1-(acetyloxy)-3,5,6,6a,7,8,9,10-octahydro-10-hydroxy-7,8-dimethyl-7-(3-methylpenta-2,4-dien-1-yl)naphtho(1,8a-c)furan-3,5-diyl dibutanoate; D004224:Diterpenes; D045785:Diterpenes, Clerodane; D010718:Phosphatidylserines; C074343:hardwickic acid; D004247:DNA; D053148:Caspase 3; D053179:Caspase 7