The Bcl-2 homology domain 3 mimetic gossypol induces both Beclin 1-dependent and Beclin 1-independent cytoprotective autophagy in cancer cells.

Abstract

Gossypol, a natural Bcl-2 homology domain 3 mimetic compound isolated from cottonseeds, is currently being evaluated in clinical trials. Here, we provide evidence that gossypol induces autophagy followed by apoptotic cell death in both the MCF-7 human breast adenocarcinoma and HeLa cell lines. We first show that knockdown of the Bcl-2 homology domain 3-only protein Beclin 1 reduces gossypol-induced autophagy in MCF-7 cells, but not in HeLa cells. Gossypol inhibits the interaction between Beclin 1 and Bcl-2 (B-cell leukemia/lymphoma 2), antagonizes the inhibition of autophagy by Bcl-2, and hence stimulates autophagy. We then show that knockdown of Vps34 reduces gossypol-induced autophagy in both cell lines, and consistent with this, the phosphatidylinositol 3-phosphate-binding protein WIPI-1 is recruited to autophagosomal membranes. Further, Atg5 knockdown also reduces gossypol-mediated autophagy. We conclude that gossypol induces autophagy in both a canonical and a noncanonical manner. Notably, we found that gossypol-mediated apoptotic cell death was potentiated by treatment with the autophagy inhibitor wortmannin or with small interfering RNA against essential autophagy genes (Vps34, Beclin 1, and Atg5). Our findings support the notion that gossypol-induced autophagy is cytoprotective and not part of the cell death process induced by this compound.

• Authors: Ping Gao, Chantal Bauvy, Sylvie Souquère, Giovanni Tonelli, Lei Liu, Yushan Zhu, Zhenzhen Qiao, Daniela Bakula, Tassula Proikas-Cezanne, Gérard Pierron, Patrice Codogno, Quan Chen, Maryam Mehrpour
• Journal: The Journal of biological chemistry (J Biol Chem) Vol. 285 Issue 33 Pg. 25570-81 (Aug 13 2010) ISSN: 1083-351X [Electronic] United States
• PMID: 20529838 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• ATG5 protein, human
• Androstadienes
• Apoptosis Regulatory Proteins
• Autophagy-Related Protein 5
• BECN1 protein, human
• Beclin-1
• Contraceptive Agents, Male
• Membrane Proteins
• Microtubule-Associated Proteins
• Protein Kinase Inhibitors
• Proto-Oncogene Proteins c-bcl-2
• RNA, Small Interfering
• Phosphatidylinositol 3-Kinases
• Gossypol
• Wortmannin

Topics

• Androstadienes (pharmacology)
• Apoptosis (drug effects)
• Apoptosis Regulatory Proteins (genetics, metabolism)
• Autophagy (drug effects, genetics)
• Autophagy-Related Protein 5
• Beclin-1
• Blotting, Western
• Cell Line, Tumor
• Contraceptive Agents, Male (pharmacology)
• Gossypol (chemistry, pharmacology)
• HeLa Cells
• Humans
• Immunoprecipitation
• Membrane Proteins (genetics, metabolism)
• Microscopy, Electron
• Microscopy, Fluorescence
• Microtubule-Associated Proteins (genetics, metabolism)
• Neoplasms (drug therapy, metabolism)
• Phosphatidylinositol 3-Kinases (genetics, metabolism)
• Protein Kinase Inhibitors (pharmacology)
• Proto-Oncogene Proteins c-bcl-2 (chemistry)
• RNA Interference
• RNA, Small Interfering (genetics, physiology)
• Wortmannin