Vanilloid receptor agonists and antagonists are mitochondrial inhibitors: How vanilloids cause non-vanilloid receptor mediated cell death
Section snippets
Materials and methods
Cells and chemicals. H460 cells (a human non-small cell lung cancer line) were obtained from the American Type Culture Collection, Manassas, VA. Drugs were dissolved in 100% ethanol at a stock concentration of 10 mM. All chemicals used were of the highest grade available and were from Sigma Chemical Company, Merck Biosciences, Tocris, or InVitrogen. For all vanilloid receptor ligands used, the diluent (ethanol) was never present at >1.0%, and control culture flasks with H460 cells or
TRPV1 ligands induce morphological features of apoptosis and necrosis in H460 cells
Figs. 1A and B show single images taken at time = 0 and time = 2 h in the time-lapse microscope in the presence of 50 μM (E)-capsaicin or 50 μM resiniferatoxin, respectively. There was a general loss of cells in the fields of view (due to their detaching from the growing surface of the cell culture plate); rounding of some individual cells (indicated by an S on the images), swelling of other individual cells (indicated by a W on the images), with an increase in cytoplasmic granularity, particularly in
Discussion
In this report, we have identified a novel mechanism for vanilloid receptor-mediated cancer cell death, which targets mitochondrial function rather than the cell-surface vanilloid receptor.
Our data showing an absence of TRPV1 immunoreactivity in mitochondria are consistent with data from MitoP2, the mitochondrial proteome database [15], which show an absence of TRPV1 channel-like proteins in the mitochondrial proteomes of man, mouse, or the model laboratory organisms Saccharomyces cerevisiae,
Acknowledgments
We thank the Medical Research Council (UK) and the School of Molecular Medical Sciences M.Sc. program in oncology, for financial support. We also thank Mr. Liaque Latif for his excellent technical assistance with SDS–PAGE and immunoblotting, and Mr. Ian Ward for outstanding technical assistance with time-lapse microscopy.
References (26)
- et al.
Transient receptor potential vanilloid subfamily 1 expressed in pancreatic islet beta cells modulates insulin secretion in rats
Biochem. Biophys. Res. Commun.
(2004) - et al.
Polyamines are potent ligands for the capsaicin receptor TRPV1
J. Biol. Chem.
(2006) - et al.
Essential role of mitochondrial permeability transition in vanilloid receptor 1-dependent cell death of sensory neurons
Mol. Cell Neurosci.
(2003) - et al.
Chlorimipramine: a novel anticancer agent with a mitochondrial target
Biochem. Biophys. Res. Commun.
(2005) - et al.
Mitochondrial nitric oxide synthase: a ubiquitous regulator of oxidative phosphorylation?
Biochem. Biophys. Res. Commun.
(1996) - et al.
A stable nonfluorescent derivative of resorufin for the fluorometric determination of trace hydrogen peroxide: applications in detecting the activity of phagocyte NADPH oxidase and other oxidases
Anal. Biochem.
(1997) - et al.
Effect of capsazepine on cytosolic Ca(2+) levels and proliferation of human prostate cancer cells
Toxicol. In Vitro
(2006) - et al.
Capsaicin and its analogs inhibit the activity of NADH-coenzyme Q oxidoreductase of the mitochondrial respiratory chain
Arch. Biochem. Biophys.
(1989) Mitochondrial involvement in drug-induced hepatic injury
Chem. Biol. Interact.
(2006)- et al.
Heat stress contributes to the enhancement of cardiac mitochondrial complex activity
Am. J. Pathol.
(2001)