Cannabidiol induces programmed cell death in breast cancer cells by coordinating the cross-talk between apoptosis and autophagy

Mol Cancer Ther. 2011 Jul;10(7):1161-72. doi: 10.1158/1535-7163.MCT-10-1100. Epub 2011 May 12.

Abstract

Cannabidiol (CBD), a major nonpsychoactive constituent of cannabis, is considered an antineoplastic agent on the basis of its in vitro and in vivo activity against tumor cells. However, the exact molecular mechanism through which CBD mediates this activity is yet to be elucidated. Here, we have shown CBD-induced cell death of breast cancer cells, independent of cannabinoid and vallinoid receptor activation. Electron microscopy revealed morphologies consistent with the coexistence of autophagy and apoptosis. Western blot analysis confirmed these findings. We showed that CBD induces endoplasmic reticulum stress and, subsequently, inhibits AKT and mTOR signaling as shown by decreased levels of phosphorylated mTOR and 4EBP1, and cyclin D1. Analyzing further the cross-talk between the autophagic and apoptotic signaling pathways, we found that beclin1 plays a central role in the induction of CBD-mediated apoptosis in MDA-MB-231 breast cancer cells. Although CBD enhances the interaction between beclin1 and Vps34, it inhibits the association between beclin1 and Bcl-2. In addition, we showed that CBD reduces mitochondrial membrane potential, triggers the translocation of BID to the mitochondria, the release of cytochrome c to the cytosol, and, ultimately, the activation of the intrinsic apoptotic pathway in breast cancer cells. CBD increased the generation of reactive oxygen species (ROS), and ROS inhibition blocked the induction of apoptosis and autophagy. Our study revealed an intricate interplay between apoptosis and autophagy in CBD-treated breast cancer cells and highlighted the value of continued investigation into the potential use of CBD as an antineoplastic agent.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adaptor Proteins, Signal Transducing / antagonists & inhibitors
  • Antineoplastic Agents / pharmacology*
  • Apoptosis / drug effects*
  • Autophagy / drug effects*
  • Breast Neoplasms / metabolism*
  • Breast Neoplasms / pathology
  • Cannabidiol / pharmacology*
  • Caspase Inhibitors
  • Cell Line, Tumor
  • Dose-Response Relationship, Drug
  • Female
  • Humans
  • Mitochondria / metabolism
  • Phosphoproteins / antagonists & inhibitors
  • Proto-Oncogene Proteins c-akt / antagonists & inhibitors
  • Reactive Oxygen Species / metabolism
  • Receptors, Estrogen / metabolism
  • Signal Transduction / drug effects
  • Stress, Physiological / drug effects
  • TOR Serine-Threonine Kinases / antagonists & inhibitors

Substances

  • Adaptor Proteins, Signal Transducing
  • Antineoplastic Agents
  • Caspase Inhibitors
  • EIF4EBP1 protein, human
  • Phosphoproteins
  • Reactive Oxygen Species
  • Receptors, Estrogen
  • Cannabidiol
  • TOR Serine-Threonine Kinases
  • Proto-Oncogene Proteins c-akt