Phenethyl isothiocyanate inhibits oxidative phosphorylation to trigger reactive oxygen species-mediated death of human prostate cancer cells.
Phenethyl isothiocyanate (PEITC), a constituent of edible cruciferous vegetables such as watercress, not only affords significant protection against chemically induced cancer in experimental rodents but also inhibits growth of human cancer cells by causing apoptotic and autophagic cell death. However, the underlying mechanism of PEITC-induced cell death is not fully understood. Using LNCaP and PC-3 human prostate cancer cells as a model, we demonstrate that the PEITC-induced cell death is initiated by production of reactive oxygen species (ROS) resulting from inhibition of oxidative phosphorylation (OXPHOS). Exposure of LNCaP and PC-3 cells to pharmacologic concentrations of PEITC resulted in ROS production, which correlated with inhibition of complex III activity, suppression of OXPHOS, and ATP depletion. These effects were not observed in a representative normal human prostate epithelial cell line (PrEC). The ROS production by PEITC treatment was not influenced by cyclosporin A. The Rho-0 variants of LNCaP and PC-3 cells were more resistant to PEITC-mediated ROS generation, apoptotic DNA fragmentation, and collapse of mitochondrial membrane potential compared with respective wild-type cells. The PEITC treatment resulted in activation of Bax in wild-type LNCaP and PC-3 cells, but not in their respective Rho-0 variants. Furthermore, RNA interference of Bax and Bak conferred significant protection against PEITC-induced apoptosis. The Rho-0 variants of LNCaP and PC-3 cells also resisted PEITC-mediated autophagy. In conclusion, the present study provides novel insight into the molecular circuitry of PEITC-induced cell death involving ROS production due to inhibition of complex III and OXPHOS.
Xiao
Dong
D
Department of Pharmacology & Chemical Biology and University of Pittsburgh Cancer Institute, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15213, USA.
Powolny
Anna A
AA
Moura
Michelle B
MB
Kelley
Eric E
EE
Bommareddy
Ajay
A
Kim
Su-Hyeong
SH
Hahm
Eun-Ryeong
ER
Normolle
Daniel
D
Van Houten
Bennett
B
Singh
Shivendra V
SV
D016588:Anticarcinogenic Agents; D016923:Cell Death; D045744:Cell Line, Tumor; D014450:Electron Transport Complex III / Q000037:antagonists & inhibitors; D006801:Humans; D017879:Isothiocyanates / Q000494:pharmacology*; D008297:Male; D010085:Oxidative Phosphorylation / Q000187:drug effects*; D011471:Prostatic Neoplasms / Q000188:drug therapy* / Q000473:pathology; D017382:Reactive Oxygen Species / Q000378:metabolism*
D016588:Anticarcinogenic Agents; D017879:Isothiocyanates; D017382:Reactive Oxygen Species; C058305:phenethyl isothiocyanate; D014450:Electron Transport Complex III