Toxicol Appl Pharmacol. 2001 Aug 1;174(3):264-72.
Tapahtuu muuttuminen solutuholaadussa apoptoottisesta tiestä nekroottiseen.
Marijuana smoke and Delta(9)-tetrahydrocannabinol promote necrotic cell death but inhibit Fas-mediated apoptosis.
Abstract
Marijuana smoke shares many components in common with tobacco smoke except for the presence of Delta(9)-tetrahydrocannabinol
(Delta(9)-THC), the psychotropic compound found only in Cannibis
sativa. Delta(9)-THC has been shown to potentiate smoke-induced
oxidative stress and necrotic cell death. In the present study, our
objective was to determine the effects of Delta(9)-THC on the balance
between Fas-induced apoptosis and necrosis in A549 lung tumor cells. We
found that Fas-induced activation of caspase-3 was inhibited by whole
smoke from both tobacco and marijuana cigarettes. Gas-phase smoke, which
generates high levels of intracellular reactive oxygen species, had no
effect on caspase-3 activity. However, particulate-phase smoke (tar) was
a potent inhibitor of Fas-induced caspase-3 activity, with marijuana
tar being more potent than either tobacco or placebo marijuana tar
(lacking Delta(9)-THC). Delta(9)-THC also inhibited Fas-induced
caspase-3 activity in A549 cells. In contrast, no inhibition was
observed when Delta(9)-THC was incubated with activated caspase-3
enzyme, suggesting that Delta(9)-THC acts on the cell pathway(s) leading
to caspase-3 activation and not directly on enzyme function. Flow
cytometry was used to measure the percentage of cells undergoing
apoptosis (staining for annexin V) versus necrosis (staining for
propidium iodide) and confirmed that both marijuana tar extract and
synthetic Delta(9)-THC inhibit Fas-induced apoptosis while promoting
necrosis. These observations suggest that the Delta(9)-THC contained in
marijuana smoke disrupts elements of the apoptotic pathway, thereby
shifting the balance between apoptotic and necrotic cell death. This
shift may affect both the carcinogenic and immunologic consequences of
marijuana smoke exposure.
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