Crocidolite asbestos inhibits pentose phosphate oxidative pathway and glucose 6-phosphate dehydrogenase activity in human lung epithelial cells.
The cytotoxicity of asbestos has been related to its ability to increase the production of reactive oxygen species (ROS), via the iron-catalyzed reduction of oxygen and/or the activation of NADPH oxidase. The pentose phosphate pathway (PPP) is generally activated by the cell exposure to oxidant molecules. Contrary to our expectations, asbestos (crocidolite) fibers caused a dose- and time-dependent inhibition of PPP and decreased its activation by an oxidative stress in human lung epithelial cells A549. In parallel, the intracellular activity of the PPP rate-limiting enzyme, glucose 6-phosphate dehydrogenase (G6PD), was significantly diminished by crocidolite exposure. This inhibition was selective, as the activity of other PPP and glycolysis enzymes was not modified, and was not attributable to a decreased expression of G6PD. On the opposite, the incubation with glass fibers MMVF10 did not modify PPP and G6PD activity. PPP and G6PD inhibition did not correlate with the increased nitric oxide (NO) production elicited by crocidolite in A549 cells. Experiments with the purified enzyme suggest that crocidolite inhibits G6PD by directly interacting with the protein. We propose here a new mechanism of asbestos-evoked oxidative stress, wherein fibers increase the intracellular ROS levels also by inhibiting the main antioxidant pathway of the cell.
Riganti
Chiara
C
Interdepartmental Center "G. Scansetti" for Studies on Asbestos and other Toxic Particulates, University of Torino, Italy.
Aldieri
Elisabetta
E
Bergandi
Loredana
L
Fenoglio
Ivana
I
Costamagna
Costanzo
C
Fubini
Bice
B
Bosia
Amalia
A
Ghigo
Dario
D
D017638:Asbestos, Crocidolite / Q000494:pharmacology*; D015153:Blotting, Western; D002478:Cells, Cultured / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism; D017931:DNA Primers / Q000737:chemistry; D004847:Epithelial Cells / Q000187:drug effects* / Q000201:enzymology; D004912:Erythrocytes / Q000378:metabolism; D005954:Glucosephosphate Dehydrogenase / Q000378:metabolism*; D005987:Glyceraldehyde-3-Phosphate Dehydrogenases / Q000378:metabolism; D006801:Humans; D007770:L-Lactate Dehydrogenase / Q000378:metabolism; D008168:Lung / Q000187:drug effects* / Q000201:enzymology; D009573:Nitrites / Q000378:metabolism; D010084:Oxidation-Reduction; D010427:Pentose Phosphate Pathway / Q000187:drug effects* / Q000502:physiology; D010734:Phosphogluconate Dehydrogenase / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction
D017931:DNA Primers; D009573:Nitrites; D017638:Asbestos, Crocidolite; D007770:L-Lactate Dehydrogenase; D010734:Phosphogluconate Dehydrogenase; D005954:Glucosephosphate Dehydrogenase; D005987:Glyceraldehyde-3-Phosphate Dehydrogenases