Artonin E Induces Apoptosis via Mitochondrial Dysregulation in SKOV-3 Ovarian Cancer Cells

PLoS One. 2016 Mar 28;11(3):e0151466. doi: 10.1371/journal.pone.0151466. eCollection 2016.

Abstract

Artonin E is a prenylated flavonoid isolated from the stem bark of Artocarpus elasticus Reinw.(Moraceae). This study aimed to investigate the apoptotic mechanisms induced by artonin E in a metastatic human ovarian cancer cell line SKOV-3 in vitro. MTT assay, clonogenic assay, acridine orange and propidium iodide double staining, cell cycle and annexin V analyses were performed to explore the mode of artonin E-induced cell death at different time points. DNA laddering, activation of caspases-3, -8, and -9, multi-parametric cytotoxicity-3 analysis by high-content screening, measurement of reactive oxygen species generation, and Western blot were employed to study the pathways involved in the apoptosis. MTT results showed that artonin E inhibited the growth of SKOV-3 cells, with IC50 values of 6.5±0.5 μg/mL after 72 h treatment, and showed less toxicity toward a normal human ovarian cell line T1074, with IC50 value of 32.5±0.5 μg/mL. Results showed that artonin E induced apoptosis and cell cycle arrest at the S phase. This compound also promoted the activation of caspases-3, -8, and -9. Further investigation into the depletion of mitochondrial membrane potential and release of cytochrome c revealed that artonin E treatment induced apoptosis via regulation of the expression of pro-survival and pro-apoptotic Bcl-2 family members. The expression levels of survivin and HSP70 proteins were also down regulated in SKOV-3 cells treated with artonin E. We propose that artonin E induced an antiproliferative effect that led to S phase cell cycle arrest and apoptosis through dysregulation of mitochondrial pathways, particularly the pro- and anti-apoptosis signaling pathways.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Apoptosis / drug effects*
  • Apoptosis / genetics
  • Artocarpus / chemistry
  • Blotting, Western
  • Caspase 3 / metabolism
  • Caspase 8 / metabolism
  • Caspase 9 / metabolism
  • Cell Line, Tumor
  • Cell Proliferation / drug effects*
  • Cell Proliferation / genetics
  • Cell Survival / drug effects
  • Cell Survival / genetics
  • Cytochromes c / metabolism
  • DNA Fragmentation / drug effects
  • Enzyme Activation / drug effects
  • Female
  • Flavonoids / chemistry
  • Flavonoids / pharmacology*
  • Flow Cytometry
  • Humans
  • Inhibitory Concentration 50
  • Mitochondria / drug effects*
  • Mitochondria / metabolism
  • Molecular Structure
  • Ovarian Neoplasms / genetics
  • Ovarian Neoplasms / metabolism
  • Ovarian Neoplasms / pathology
  • Proto-Oncogene Proteins c-bcl-2 / metabolism
  • Reactive Oxygen Species / metabolism
  • S Phase Cell Cycle Checkpoints / drug effects
  • S Phase Cell Cycle Checkpoints / genetics

Substances

  • Flavonoids
  • Proto-Oncogene Proteins c-bcl-2
  • Reactive Oxygen Species
  • artonin E
  • Cytochromes c
  • Caspase 3
  • Caspase 8
  • Caspase 9

Grants and funding

The authors wish to thank University of Malaya for providing the research grants under UMRG project (RG077- 12BIO), Institute of Research Management and Monitoring Research Grant (PG162-2014B), and Ministry of Higher Education Malaysia under High Impact Research Grant (UM-MOHE UM.C/625/1/HIR/MOHE/SC/09) for their financial support to carry out this research.