Reactive Oxygen Species Mediate Caspase Activation and Apoptosis Induced by Lipoic Acid in Human Lung Epithelial Cancer Cells Through Bcl-2 Down-Regulation

Details

• Personal Author:
  Azad N ; Callery PS ; Chanvorachote P ; Lipipun V ; Moungjaroen J ; Nimmannit U ; Rojanasakul Y ; Wang L
• Description:
  The antioxidant alpha-lipoic acid (LA) is a naturally occurring compound that has been shown to possess promising anticancer activity because of its ability to preferentially induce apoptosis and inhibit proliferation of cancer cells relative to normal cells. However, the molecular mechanisms underlying the apoptotic effect of LA are not well understood. We report here that LA induced reactive oxygen species (ROS) generation and a concomitant increase in apoptosis of human lung epithelial cancer H460 cells. Inhibition of ROS generation by ROS scavengers or by overexpression of antioxidant enzymes glutathione peroxidase and superoxide dismutase effectively inhibited LA-induced apoptosis, indicating the role of ROS, especially hydroperoxide and superoxide anion, in the apoptotic process. Apoptosis induced by LA was found to be mediated through the mitochondrial death pathway, which requires caspase-9 activation. Inhibition of caspase activity by the pan-caspase inhibitor (z-VAD-FMK) or caspase-9-specific inhibitor (z-LEHD-FMK) completely inhibited the apoptotic effect of LA. Likewise, the mitochondrial respiratory chain inhibitor rotenone potently inhibited the apoptotic and ROS-inducing effects of LA, supporting the role of mitochondrial ROS in LA-induced cell death. LA induced down-regulation of mitochondrial Bcl-2 protein through peroxide-dependent proteasomal degradation, and overexpression of the Bcl-2 protein prevented the apoptotic effect of LA. Together, our findings indicate a novel pro-oxidant role of LA in apoptosis induction and its regulation by Bcl-2, which may be exploited for the treatment of cancer and related apoptosis disorders. [Description provided by NIOSH]
• Subjects:
  Antioxidants Lung Lung Diseases Neoplasms Occupational Health Respiratory System Respiratory Tract Diseases Safety
• Keywords:
  Antioxidation Cancer Lung-cancer Pharmacology Therapeutic-agents
• ISSN:
  0022-3565
• Document Type:
  Text
• Genre:
  Journal Article
• Place as Subject:
  OSHA Region 3 ; West Virginia
• CIO:
  National Institute for Occupational Safety and Health (NIOSH)
• Division:
  HELD - Health Effects Laboratory Division
• Topic:
  Workplace Safety & Health
• Location:
  North America
• Volume:
  319
• Issue:
  3
• NIOSHTIC Number:
  nn:20031255
• Citation:
  J Pharmacol Exp Ther 2006 Dec; 319(3):1062-1069
• Email:
  yrojanasakul@hsc.wvu.edu
• Federal Fiscal Year:
  2007
• NORA Priority Area:
  Work Environment and Workforce: Emerging Technologies
• Peer Reviewed:
  True
• Source Full Name:
  Journal of Pharmacology and Experimental Therapeutics
• Collection(s):
  National Institute for Occupational Safety and Health
• Main Document Checksum:
  urn:sha-512:2ab788e46b09819bb857b0ddec788ffa9c29725444fbcccba71baaa8e92a8a13cebf6af3fcaec1cb306a0485002adbcf6bb8366cb16aa278ea723f7fb63bd065
• Download URL:
  https://stacks.cdc.gov/view/cdc/191559/cdc_191559_DS1.pdf
• File Type:
  [PDF - 420.12 KB ]