Prevention of Deoxycholate-Induced Gastric Apoptosis by Aspirin: Roles of NF-κB and PKC Signaling

• Published in: The Journal of surgical research 2008-03, Vol.145 (1), p.66-73
• Main Authors: Redlak, Maria J., Ph.D, Power, Jacinda J., M.Sc, Miller, Thomas A., M.D
• Format: Article
• Language: English
• Subjects: bile acid; human gastric cancer epithelial cell line; injury and protection; Surgery
• ISSN: 0022-4804; 1095-8673
• DOI: 10.1016/j.jss.2007.04.039

Background Apoptosis is a major mechanism of gastric cell death induced by deoxycholate (DC) and aspirin (ASA), and the caspase cascade and protein kinase C (PKC) signaling play key roles in this process. The transcription factor kappa B (NF-κB) has been shown to modulate apoptosis by regulating the transcription of numerous pro- and anti-apoptotic genes. The aim of this study was to investigate the effect of DC and ASA on NF-κB signaling, and determine its role in programmed cell death in a human gastric carcinoma cell line. Methods Cells were incubated with DC in the presence or absence of ASA or proteasome inhibitors (PI- I, lactacystin, and MG-132). Cell lysates were evaluated by Western blotting. NF-κB (p65) was measured in the cytosol and nuclear fractions. Results DC induced a translocation of NF-κB into the nuclear compartment that was completely blocked by proteasome inhibitors. Although, ASA itself had no effect on the NF-κB pathway, nor did it reduce DC-induced NF-κB translocation, it did prevent DC-induced caspase-3, -6 and -9 activation, poly (ADP-ribose) polymerase and lamin A processing, DNA degradation, and PKC signaling, all indices of apoptosis. In contrast, proteasome inhibitors had no effect on DC-induced apoptosis. Conclusions Deoxycholate activates NF-κB at the same time that it induces apoptosis in gastric epithelial cells. Prevention of NF-κB activation does not alter DC-induced apoptosis, indicating that in our experimental conditions, NF-κB is not essential for apoptosis to proceed. In contrast, the ability of aspirin to restore the alterations in PKC isoforms induced by DC and at the same time prevent caspase cascade activation suggests the importance of the PKC signaling system in this process.