title: Parthenolide and DMAPT exert cytotoxic effects on breast cancer stem-like cells by inducing oxidative stress, mitochondrial dysfunction and necrosis.
abstract: Triple-negative breast cancers (TNBCs) are aggressive forms of breast carcinoma associated with a high rate of recidivism. In this paper, we report the production of mammospheres from three lines of TNBC cells and demonstrate that both parthenolide (PN) and its soluble analog dimethylaminoparthenolide (DMAPT) suppressed this production and induced cytotoxic effects in breast cancer stem-like cells, derived from dissociation of mammospheres. In particular, the drugs exerted a remarkable inhibitory effect on viability of stem-like cells. Such an effect was suppressed by N-acetylcysteine, suggesting a role of reactive oxygen species (ROS) generation in the cytotoxic effect. Instead z-VAD, a general inhibitor of caspase activity, was ineffective. Analysis of ROS generation, performed using fluorescent probes, showed that both the drugs stimulated in the first hours of treatment a very high production of hydrogen peroxide. This event was, at least in part, a consequence of activation of NADPH oxidases (NOXs), as it was reduced by apocynin and diphenylene iodinium, two inhibitors of NOXs. Moreover, both the drugs caused downregulation of Nrf2 (nuclear factor erythroid 2-related factor 2), which is a critical regulator of the intracellular antioxidant response. Prolonging the treatment with PN or DMAPT we observed between 12 and 24 h that the levels of both superoxide anion and hROS increased in concomitance with the downregulation of manganese superoxide dismutase and catalase. In addition, during this phase dissipation of mitochondrial membrane potential occurred together with necrosis of stem-like cells. Finally, our results suggested that the effect on ROS generation found in the first hours of treatment was, in part, responsible for the cytotoxic events observed in the successive phase. In conclusion, PN and DMAPT markedly inhibited viability of stem-like cells derived from three lines of TNBCs by inducing ROS generation, mitochondrial dysfunction and cell necrosis.
authors.affiliation: Laboratory of Biochemistry, Department of Experimental Biomedicine and Clinical Neurosciences (BioNec), University of Palermo, Polyclinic, Palermo, Italy.
authors.forename: D
authors.initials: D
authors.lastname: Carlisi
authors.affiliation: Laboratory of Biochemistry, Department of Biological, Chemical and Pharmaceutical Sciences and Technologies (STEBICEF), University of Palermo, Polyclinic, Palermo, Italy.
authors.forename: G
authors.initials: G
authors.lastname: Buttitta
authors.affiliation: Laboratory of Biochemistry, Department of Biological, Chemical and Pharmaceutical Sciences and Technologies (STEBICEF), University of Palermo, Polyclinic, Palermo, Italy.
authors.forename: R
authors.initials: R
authors.lastname: Di Fiore
authors.affiliation: Department of Physiology and Biochemistry, University of Malta, Msida, Malta.
authors.forename: C
authors.initials: C
authors.lastname: Scerri
authors.affiliation: Laboratory of Biochemistry, Department of Biological, Chemical and Pharmaceutical Sciences and Technologies (STEBICEF), University of Palermo, Polyclinic, Palermo, Italy.
authors.forename: R
authors.initials: R
authors.lastname: Drago-Ferrante
authors.affiliation: Laboratory of Biochemistry, Department of Biological, Chemical and Pharmaceutical Sciences and Technologies (STEBICEF), University of Palermo, Polyclinic, Palermo, Italy.|Sbarro Institute for Cancer Research and Molecular Medicine, Center for Biotechnology, Temple University, Philadelphia, PA, USA.
authors.forename: R
authors.initials: R
authors.lastname: Vento
authors.affiliation: Laboratory of Biochemistry, Department of Experimental Biomedicine and Clinical Neurosciences (BioNec), University of Palermo, Polyclinic, Palermo, Italy.|Sbarro Institute for Cancer Research and Molecular Medicine, Center for Biotechnology, Temple University, Philadelphia, PA, USA.
authors.forename: G
authors.initials: G
authors.lastname: Tesoriere
mesh_terms: D000098:Acetophenones / Q000494:pharmacology; D001943:Breast Neoplasms / Q000378:metabolism / Q000473:pathology; D045744:Cell Line, Tumor; D002470:Cell Survival / Q000187:drug effects; D005260:Female; D005456:Fluorescent Dyes / Q000737:chemistry / Q000378:metabolism; D006801:Humans; D053078:Membrane Potential, Mitochondrial / Q000187:drug effects; D008928:Mitochondria / Q000187:drug effects* / Q000378:metabolism; D019255:NADPH Oxidases / Q000037:antagonists & inhibitors / Q000378:metabolism; D051267:NF-E2-Related Factor 2 / Q000235:genetics / Q000378:metabolism; D014411:Neoplastic Stem Cells / Q000166:cytology / Q000378:metabolism; D009842:Oligopeptides / Q000494:pharmacology; D009861:Onium Compounds / Q000494:pharmacology; D018384:Oxidative Stress / Q000187:drug effects*; D017382:Reactive Oxygen Species / Q000378:metabolism; D060888:Real-Time Polymerase Chain Reaction; D012717:Sesquiterpenes / Q000633:toxicity*; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism
chemical_list: D000098:Acetophenones; D005456:Fluorescent Dyes; C524858:LC-1 compound; D051267:NF-E2-Related Factor 2; C495635:NFE2L2 protein, human; D009842:Oligopeptides; D009861:Onium Compounds; D017382:Reactive Oxygen Species; D012717:Sesquiterpenes; D014157:Transcription Factors; C517629:benzyloxycarbonyl-valyl-alanyl-aspartic acid; C002669:parthenolide; C007517:diphenyleneiodonium; C056165:acetovanillone; D019255:NADPH Oxidases