Isoorientin induces apoptosis and autophagy simultaneously by reactive oxygen species (ROS)-related p53, PI3K/Akt, JNK, and p38 signaling pathways in HepG2 cancer cells

J Agric Food Chem. 2014 Jun 11;62(23):5390-400. doi: 10.1021/jf500903g. Epub 2014 Jun 3.


Cell death is closely related to autophagy under some circumstances; however, the effect of isoorientin (ISO) on autophagy and the interplay between apoptosis and autophagy in human hepatoblastoma cancer (HepG2) cells remains poorly understood. The present study showed that ISO induced autophagy, which was correlated with the formation of autophagic vacuoles and the overexpression of Beclin-1 and LC3-II. The autophagy inhibitor 3-methyladenine (3-MA) markedly inhibited apoptosis, and the apoptosis inhibitor ZVAD-fmk also decreased ISO-induced autophagy. In addition, the PI3K/Akt inhibitor LY294002 enhanced Beclin-1, LC3-II, and poly(ADP-ribose) polymerase (PARP) cleavage levels. Also, the reactive oxygen species (ROS) inhibitor N-acetyl-L-cysteine (NAC), the JNK inhibitor SP600125, and the p38 inhibitor SB203580 efficiently downregulated the levels of these proteins. Moreover, the p53 inhibitor pifithrin-α and the nuclear factor (NF)-κB inhibitor pyrrolidinedithiocarbamic acid (PDTC) clearly suppressed Beclin-1 and LC3-II and increased cytochrome c release, caspase-3 activation, and PARP cleavage. These results demonstrated for the first time that ISO simultaneously induced apoptosis and autophagy by ROS-related p53, PI3K/Akt, JNK, and p38 signaling pathways. Furthermore, ISO-induced apoptosis by activating the Fas receptor-mediated apoptotic pathway and suppressing the p53 and PI3K/Akt-dependent NF-κB signaling pathway, with the subsequent increase in the release of cytochrome c, caspase-3 activation, and PARP cleavage.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Antineoplastic Agents / pharmacology*
  • Apoptosis / drug effects*
  • Autophagy / drug effects*
  • Hep G2 Cells
  • Humans
  • Liver Neoplasms / drug therapy
  • Liver Neoplasms / enzymology
  • Liver Neoplasms / genetics
  • Liver Neoplasms / metabolism*
  • Luteolin / pharmacology*
  • MAP Kinase Kinase 4 / genetics
  • MAP Kinase Kinase 4 / metabolism
  • MAP Kinase Signaling System / drug effects*
  • Oncogene Protein v-akt / genetics
  • Oncogene Protein v-akt / metabolism
  • Phosphatidylinositol 3-Kinases / genetics
  • Phosphatidylinositol 3-Kinases / metabolism
  • Reactive Oxygen Species / metabolism*
  • Tumor Suppressor Protein p53 / genetics
  • Tumor Suppressor Protein p53 / metabolism*
  • p38 Mitogen-Activated Protein Kinases / genetics
  • p38 Mitogen-Activated Protein Kinases / metabolism


  • Antineoplastic Agents
  • Reactive Oxygen Species
  • TP53 protein, human
  • Tumor Suppressor Protein p53
  • homoorientin
  • Phosphatidylinositol 3-Kinases
  • Oncogene Protein v-akt
  • p38 Mitogen-Activated Protein Kinases
  • MAP Kinase Kinase 4
  • Luteolin