Arsenic trioxide induces a beclin-1-independent autophagic pathway via modulation of SnoN/SkiL expression in ovarian carcinoma cells

Cell Death Differ. 2010 Dec;17(12):1867-81. doi: 10.1038/cdd.2010.53. Epub 2010 May 28.

Abstract

Arsenic trioxide (As(2)O(3)), used to treat promyelocytic leukemia, triggers cell death through unknown mechanisms. To further our understanding of As(2)O(3)-induced death, we analyzed its effects on transforming growth factor-β (TGFβ) signaling mediators in ovarian cells. Dysregulated TGFβ signaling is a characteristic of ovarian cancers. As(2)O(3) reduced the protein expression of EVI1, TAK1, SMAD2/3, and TGFβRII while increasing SnoN/SkiL. EVI1 protein was modulated by treatment with the proteasome inhibitors, MG132 and PS-341/Velcade, suggesting that degradation occurs through the ubiquitin-proteasome pathway. The sensitivity of ovarian cells to As(2)O(3)-induced apoptosis correlated with expression of multidrug resistance protein 1. Interestingly, expression of SnoN was similar to LC3-II (autophagy marker), which increased with induction of cytoplasmic vacuolation preceding apoptosis. These vesicles were identified as autophagosomes based on transmission electron microscopy and immunofluorescence staining with EGFP-LC3. The addition of N-acetyl-L-cysteine (ROS scavenger) to As(2)O(3)-treated cells reversed changes in SnoN protein and the autophagic/apoptotic response. In contrast to beclin-1 knockdown, siRNA targeting ATG5, ATG7, and hVps34 markedly reduced autophagy in As(2)O(3)-treated ovarian carcinoma cells. Further, treatment with SnoN siRNA markedly decreased LC3-II levels and increased PARP degradation (an apoptosis marker). Collectively, these findings suggest that As(2)O(3) induces a beclin-1-independent autophagic pathway in ovarian carcinoma cells and implicates SnoN in promoting As(2)O(3)-mediated autophagic cell survival.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Acetylcysteine / pharmacology
  • Apoptosis Regulatory Proteins / genetics
  • Apoptosis Regulatory Proteins / metabolism*
  • Arsenic Trioxide
  • Arsenicals
  • Autophagy*
  • Autophagy-Related Protein 5
  • Autophagy-Related Protein 7
  • Beclin-1
  • Carcinoma / metabolism*
  • Cell Line, Tumor
  • Female
  • Humans
  • Intracellular Signaling Peptides and Proteins / genetics
  • Intracellular Signaling Peptides and Proteins / metabolism*
  • Membrane Proteins / genetics
  • Membrane Proteins / metabolism*
  • Microtubule-Associated Proteins / genetics
  • Microtubule-Associated Proteins / metabolism
  • Multidrug Resistance-Associated Proteins / metabolism
  • Ovarian Neoplasms / metabolism*
  • Oxides / toxicity*
  • Poly(ADP-ribose) Polymerases / metabolism
  • Proto-Oncogene Proteins / genetics
  • Proto-Oncogene Proteins / metabolism*
  • RNA Interference
  • RNA, Small Interfering / metabolism
  • Reactive Oxygen Species / metabolism
  • Signal Transduction
  • Transforming Growth Factor beta / metabolism
  • Ubiquitin-Activating Enzymes / genetics
  • Ubiquitin-Activating Enzymes / metabolism

Substances

  • ATG5 protein, human
  • Apoptosis Regulatory Proteins
  • Arsenicals
  • Autophagy-Related Protein 5
  • BECN1 protein, human
  • Beclin-1
  • Intracellular Signaling Peptides and Proteins
  • Membrane Proteins
  • Microtubule-Associated Proteins
  • Multidrug Resistance-Associated Proteins
  • Oxides
  • Proto-Oncogene Proteins
  • RNA, Small Interfering
  • Reactive Oxygen Species
  • SKIL protein, human
  • Transforming Growth Factor beta
  • light chain 3, human
  • Poly(ADP-ribose) Polymerases
  • Atg7 protein, human
  • Autophagy-Related Protein 7
  • Ubiquitin-Activating Enzymes
  • Arsenic Trioxide
  • Acetylcysteine
  • multidrug resistance-associated protein 1