The microtubule depolymerizing agent naphthazarin induces both apoptosis and autophagy in A549 lung cancer cells

Apoptosis. 2011 Sep;16(9):924-39. doi: 10.1007/s10495-011-0613-1.


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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Apoptosis*
  • Autophagy*
  • Carcinoma, Non-Small-Cell Lung / metabolism
  • Carcinoma, Non-Small-Cell Lung / pathology
  • Caspase 3 / metabolism
  • Cell Cycle
  • Cell Cycle Checkpoints
  • Cell Line, Tumor / drug effects
  • Cell Survival
  • Cell-Free System / metabolism
  • Dose-Response Relationship, Drug
  • Flow Cytometry
  • Humans
  • Immunoprecipitation
  • Inhibitory Concentration 50
  • Microscopy, Confocal
  • Microtubules / drug effects*
  • Microtubules / metabolism
  • Mitochondria / metabolism
  • Mitochondrial Proteins / metabolism
  • Mitotic Index
  • Molecular Structure
  • Naphthoquinones / pharmacology*
  • Poly(ADP-ribose) Polymerases / metabolism
  • Proto-Oncogene Proteins c-akt / metabolism
  • Signal Transduction
  • Tubulin / metabolism
  • Tumor Suppressor Protein p53 / metabolism
  • bcl-2-Associated X Protein / metabolism


  • BAX protein, human
  • Mitochondrial Proteins
  • Naphthoquinones
  • Tubulin
  • Tumor Suppressor Protein p53
  • bcl-2-Associated X Protein
  • naphthazarin
  • Poly(ADP-ribose) Polymerases
  • Proto-Oncogene Proteins c-akt
  • CASP3 protein, human
  • Caspase 3