Cellular responses to cancer chemopreventive agent D,L-sulforaphane in human prostate cancer cells are initiated by mitochondrial reactive oxygen species

Pharm Res. 2009 Jul;26(7):1729-38. doi: 10.1007/s11095-009-9883-5. Epub 2009 Apr 21.

Abstract

Purpose: Present study was undertaken to elucidate the mechanism of cellular responses to D,L-sulforaphane (SFN), a highly promising cancer chemopreventive agent.

Methods: Mitochondrial DNA deficient Rho-0 variants of LNCaP and PC-3 cells were generated by culture in the presence of ethidium bromide. Apoptosis was assessed by analysis of cytoplasmic histone-associated DNA fragmentation and activation of caspase-3. Immunoblotting was performed to determine the expression of apoptosis- and cell cycle-regulating proteins. Generation of reactive oxygen species (ROS), mitochondrial membrane potential (MMP), and cell cycle distribution were measured by flow cytometry.

Results: The Rho-0 variants of LNCaP and PC-3 cells were significantly more resistant to SFN-induced ROS generation, apoptotic DNA fragmentation, disruption of MMP, cytosolic release of cytochrome c, and G2/M phase cell cycle arrest compared with corresponding wild-type cells. SFN-induced autophagy, which serves to protect against apoptotic cell death in PC-3 and LNCaP cells, was also partially but markedly suppressed in Rho-0 variants compared with wild-type cells. SFN statistically significantly inhibited activities of mitochondrial respiratory chain enzymes in LNCaP and PC-3 cells.

Conclusion: These results indicate, for the first time, that mitochondria-derived ROS serve to initiate diverse cellular responses to SFN exposure in human prostate cancer cells.

Publication types

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

MeSH terms

  • Anticarcinogenic Agents / pharmacology*
  • Anticarcinogenic Agents / therapeutic use
  • Apoptosis / drug effects
  • Caspase 3 / metabolism
  • Cell Cycle / drug effects
  • Cell Line, Tumor
  • Electron Transport / drug effects
  • Gene Deletion
  • Humans
  • Isothiocyanates
  • Male
  • Membrane Potential, Mitochondrial / drug effects
  • Mitochondria / drug effects*
  • Mitochondria / genetics
  • Mitochondria / metabolism*
  • Prostatic Neoplasms / drug therapy*
  • Proto-Oncogene Proteins c-bcl-2 / metabolism
  • Reactive Oxygen Species / metabolism*
  • Signal Transduction / drug effects
  • Thiocyanates / pharmacology*
  • Thiocyanates / therapeutic use
  • rho GTP-Binding Proteins / genetics
  • rho GTP-Binding Proteins / metabolism

Substances

  • Anticarcinogenic Agents
  • Isothiocyanates
  • Proto-Oncogene Proteins c-bcl-2
  • Reactive Oxygen Species
  • Thiocyanates
  • Caspase 3
  • rho GTP-Binding Proteins
  • sulforaphane