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Medical AI Inquiry: You was designed to assist in medical decision-making based on the provided user questions. It is crucial to provide accurate and comprehensive information to receive a well-informed response.  Labels: OBJECTIVE, METHODS, RESULTS. Meshes: Animals, Apoptosis, Bile Ducts, Cell Line, Tumor, Cyclooxygenase 2, Dose-Response Relationship, Drug, Enzyme Induction, Gene Expression Profiling, Humans, Lysophosphatidylcholines, Male, Proto-Oncogene Proteins c-raf, RNA, Messenger, Rats, Rats, Sprague-Dawley, Reverse Transcriptase Polymerase Chain Reaction.
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Does lysophosphatidylcholine suppress apoptotic cell death by inducing cyclooxygenase-2 expression via a Raf-1 dependent mechanism in human cholangiocytes? Context: The high incidence of biliary tract carcinoma in patients with anomalous pancreaticobiliary ductal junction (APBDJ) implicates that a compositional alteration in bile may contribute to the genesis of this cancer. Lysophosphatidylcholine (LPC) is generated in the bile of these patients. Given the role of cyclooxygenase-2 (COX-2) in biliary tract carcinogenesis, we postulated that LPC induces COX-2 in cholangiocytes. The effect of LPC on COX-2 expression in cholangiocytes was evaluated by immunoblot analysis, real-time PCR and reporter gene assay. Apoptosis was induced by TRAIL treatment, and quantified using DAPI staining. Lysophosphatidylcholine increased COX-2 protein expression in cholangiocytes in a concentration- and time-dependent manner. LPC-induced Raf-1 activation was responsible for this COX-2 induction. Accordingly, LPC increased COX-2 mRNA levels in a Raf-1 dependent manner by stabilizing COX-2 mRNA. Finally, LPC attenuated TRAIL-mediated apoptosis through a COX-2/PgE2 dependent mechanism.
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Collectively, these results implicate that LPC inhibits cholangiocyte apoptosis by inducing COX-2 expression via a Raf-1 dependent mechanism. This anti-apoptotic signaling may participate in biliary tract carcinogenesis in APBDJ patients, and therefore, its interruption may be a viable chemopreventative strategy. Final Decision: yes