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COX‐2 inhibits Fas‐mediated apoptosis in cholangiocarcinoma cells
Author(s) -
Nzeako Ugochukwu C.,
Guicciardi Maria Eugenia,
Yoon JungHwan,
Bronk Steven F.,
Gores Gregory J.
Publication year - 2002
Publication title -
hepatology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.488
H-Index - 361
eISSN - 1527-3350
pISSN - 0270-9139
DOI - 10.1053/jhep.2002.31774
Subject(s) - apoptosis , fas ligand , transfection , programmed cell death , fas receptor , cancer research , tumor necrosis factor alpha , receptor , prostaglandin e2 receptor , prostaglandin e2 , death domain , cell culture , biology , agonist , microbiology and biotechnology , endocrinology , medicine , biochemistry , genetics
Fas expression has been shown to negatively regulate the progression of cholangiocarcinoma cells in xenografts. However, many human cholangiocarcinomas express Fas, suggesting these cancers have developed mechanisms to inhibit Fas‐mediated apoptosis. Cyclooxygenase‐2 (COX‐2), which generates prostanoids, is expressed by many cholangiocarcinomas. Therefore, our aim was to determine whether COX‐2 expression inhibits death receptor–mediated apoptosis in KMBC cells, a cholangiocarcinoma cell line. These cells express messenger RNA for the death receptors Fas, tumor necrosis factor receptor 1 (TNF‐R1), death receptor 4 (DR4), and DR5. Agonists for these death receptors, CH‐11, TNF‐α, and TRAIL all induced apoptosis. However, COX‐2, whether induced by proinflammatory cytokines or transient transfection, only significantly inhibited Fas‐mediated apoptosis. The COX‐2 inhibitor NS‐398 restored Fas‐mediated apoptosis in COX‐2 transfected cells. Prostaglandin E2 reduced apoptosis and mitochondrial depolarization after treatment with the Fas agonist CH‐11. Of a variety of antiapoptotic proteins examined, COX‐2/prostaglandin E2 only increased expression of Mcl‐1, an antiapoptotic member of the Bcl‐2 family. In conclusion, these data suggest that prostanoid generation by COX‐2 specifically inhibits Fas‐mediated apoptosis, likely by up‐regulating Mcl‐1 expression. Pharmacologic inhibition of COX‐2 may be useful in augmenting Fas‐mediated apoptosis of cholangiocarcinoma cells.