title: The microtubule depolymerizing agent naphthazarin induces both apoptosis and autophagy in A549 lung cancer cells.
abstract: Naphthazarin (DHNQ, 5,8-dihydroxy-l,4-naphthoquinone) is a naturally available 1,4-naphthoquinone derivatives. In this study, we focused on elucidating the cytotoxic mechanism of naphthazarin in A549 non-small cell lung carcinoma cells. Naphthazarin reduced the A549 cell viability considerably with an IC(50) of 16.4 ± 1.6 μM. Naphthazarin induced cell death in a dose- and time-dependent manner by activating apoptosis and autophagy pathways. Specifically, we found naphthazarin inhibited the PI3K/Akt cell survival signalling pathway, measured by p53 and caspase-3 activation, and PARP cleavage. It also resulted in an increase in the ratio of Bax/Bcl2 protein levels, indicating activation of the mitochondrial apoptotic pathway. Similarly naphthazarin triggered LC3II expression and induced autophagic flux in A549 cells. We demonstrated further that naphthazarin is a microtubule inhibitor in cell-free system and in A549 cells. Naphthazarin treatment depolymerized interphase microtubules and disorganised spindle microtubules and the majority of cells arrested at the G(2)/M transition. Together, these data suggest that naphthazarin, a microtubule depolymerizer which activates dual cell death machineries, could be a potential novel chemotherapeutic agent.
authors.affiliation: Department of Biotechnology and Dr. B.C. Guha Centre for Genetic Engineering and Biotechnology, University of Calcutta, Kolkata, WB, India.
authors.forename: Bipul R
authors.initials: BR
authors.lastname: Acharya
authors.forename: Surela
authors.initials: S
authors.lastname: Bhattacharyya
authors.forename: Diptiman
authors.initials: D
authors.lastname: Choudhury
authors.forename: Gopal
authors.initials: G
authors.lastname: Chakrabarti
mesh_terms: D017209:Apoptosis; D001343:Autophagy; D002289:Carcinoma, Non-Small-Cell Lung / Q000378:metabolism / Q000473:pathology; D053148:Caspase 3 / Q000378:metabolism; D002453:Cell Cycle; D059447:Cell Cycle Checkpoints; D045744:Cell Line, Tumor / Q000187:drug effects; D002470:Cell Survival; D002474:Cell-Free System / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D005434:Flow Cytometry; D006801:Humans; D047468:Immunoprecipitation; D020128:Inhibitory Concentration 50; D018613:Microscopy, Confocal; D008870:Microtubules / Q000187:drug effects* / Q000378:metabolism; D008928:Mitochondria / Q000378:metabolism; D024101:Mitochondrial Proteins / Q000378:metabolism; D008940:Mitotic Index; D015394:Molecular Structure; D009285:Naphthoquinones / Q000494:pharmacology*; D011065:Poly(ADP-ribose) Polymerases / Q000378:metabolism; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D015398:Signal Transduction; D014404:Tubulin / Q000378:metabolism; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism; D051028:bcl-2-Associated X Protein / Q000378:metabolism
chemical_list: C494826:BAX protein, human; D024101:Mitochondrial Proteins; D009285:Naphthoquinones; D014404:Tubulin; D016159:Tumor Suppressor Protein p53; D051028:bcl-2-Associated X Protein; C005503:naphthazarin; D011065:Poly(ADP-ribose) Polymerases; D051057:Proto-Oncogene Proteins c-akt; C505407:CASP3 protein, human; D053148:Caspase 3