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NO-mesalamine protects colonic epithelial cells against apoptotic damage induced by proinflammatory cytokines
S Fiorucci1, E Distrutti, M N Ajuebor
1Clinica di Gastroenterologia ed Epatologia, Dipartimento di Medicina Clinica e Sperimentale, Università degli Studi di Perugia, 06100 Perugia, Italy. fiorucci@unipg.it
Abstract:
The activation of a self-amplifying cascade of caspases, of which caspase-8 is the apical protease, mediates Fas-, tumor necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL)-, and TNF-alpha-induced apoptosis in colon cell lines. Nitric oxide (NO) protects from apoptosis induced by Fas and TNF-alpha. We examined whether NCX-456, an NO-releasing derivative of mesalamine, protects colon epithelial cells from cytokine-induced apoptosis. Caco-2 and HT-29 cell lines express death factor receptors and are driven to apoptosis in response to incubation with Fas-agonistic antibody, TNF-alpha/interferon-gamma, and TRAIL. The two novel observations reported here are that 1) cotreatment of cells with NCX-456, but not mesalamine, resulted in concentration-dependent protection against death factor-induced apoptosis and inhibition of caspase activity, and 2) exposure to dithiothreitol, an agent that effectively removes NO from thiol groups, resulted in a 70% recovery of caspase activity, which is consistent with S-nitrosation as a major mechanism for caspase inactivation. These data suggest that caspase S-nitrosation represents a mechanism for protection of colonic mucosal epithelial cells from death factor-induced death.
Insights
NCX-456, a nitric oxide (NO)-releasing mesalamine derivative, protects colon cells from apoptosis by inhibiting caspases. This protection is mediated by NO-releasing S-nitrosation, a novel mechanism for preventing cell death.
Area of Science:
- Cell Biology
- Molecular Biology
- Gastroenterology
Background:
- Caspase activation mediates apoptosis induced by death receptors like Fas and TNF-alpha.
- Nitric oxide (NO) is known to protect cells from apoptosis.
- Colon epithelial cells are susceptible to cytokine-induced apoptosis.
Purpose of the Study:
- To investigate the protective effects of NCX-456, an NO-releasing mesalamine derivative, against cytokine-induced apoptosis in colon epithelial cells.
- To elucidate the mechanism by which NCX-456 confers protection.
Main Methods:
- Caco-2 and HT-29 colon cell lines were used.
- Cells were treated with death factor agonists (Fas-agonistic antibody, TNF-alpha/interferon-gamma, TRAIL).
- Cells were cotreated with NCX-456 or mesalamine and subsequently with dithiothreitol.
Main Results:
- NCX-456, but not mesalamine, provided concentration-dependent protection against death factor-induced apoptosis.
- NCX-456 inhibited caspase activity.
- Dithiothreitol treatment recovered 70% of caspase activity, indicating S-nitrosation as a key mechanism.
Conclusions:
- NCX-456 protects colon epithelial cells from death receptor-mediated apoptosis.
- Caspase S-nitrosation by NO is a significant mechanism for protecting colonic mucosal cells from apoptosis.