| Cholangiocarcinoma is one of the common neoplasms in the biliary tract,Due to lack of specific symptoms and signs .its unique biological characteristics and its anatomic features ,it is very difficult to diagnose patients with cholangiocarcinoma in the early stage and resect the tumour radically .Along with its sensitivity to chemotherapy and radiotherapy,the prognosis is still very poor. Recent years, the incidence rate and the mortality rate of cholangiocarcinoma is increasing markedly, so it is regarded as crucial to study the carcinogenesis mechanism of cholangiocarcinoma and find new efffective therapeutic approaches of them. Cyclooxygenase (COX) also known as prostaglandin endoperoxide synthase,is a membrane-bound biofuncation enzyme which catalyzes the convertion of arachidonic acid to prostaglandins. It has two isoenzymes,COX-l and COX-2,they have different biological function. COX-1 is expressed constitutively in many human tissues and is important for the maintenance of homeostatic functions including synthesis of cytoprotective gastrointestinal prostaglandins and the modulation of platelet agreggation. In contrast, COX-2,the other prostaglandin synthetase, is a type of inducible enzyme .Under normal condition, it is not detected ,but can be induced by Various kinds of cytokine such as lipopolysaccharide(LPS), interleukin-1 (IL-1), tumor necrosis factor (TNF), epidermal growth factor EGF, transforming growth factor (TGF) quickly and continuously . COX-2 has been found high expression in colonic, gastric and liver carcinoma and is related to occurrence and development of them in recent years. Epidemiologic studies have indicated that long term NASIDs treatment reduced the number and size of colonic adenomas and carcinomas in patients withfamilial adenomatous polyposis. Further studies show that NASIDs can inhibit the protein expression of COX-2 and induce apoptosis of tumour cells. Since COX-2 is overexpressioned in approximately 70% of Cholangiocarcinomas, indicated that COX-2 may be a new target for prevention and therapy of them. In this study, the effect of a selective COX-2 inhibitor nimesulide on the growth of human cholangiocarcinoma cell line QBC939 was investigated , we hope we would provide a few certain proofs for clinic therapy with COX-2 inhibitor through evaluting the growth-inhibiting and apoptosis-inducing effects of nimesulide on human cholangiocarcinoma cell line QBC939 cultured in vitro.Objective To investigate the effect of a select COX-2 inhibitor nimesulide on human cholangiocarcinoma QBC939 cell line in vitro and its probable mechanisms.Methods QBC939 cells were cultured in vitro and seeded into culture plates. At the state of culturing, observe the morphology of cells in culture flask by invert microscope every day. Following exposure to nimesulide at different concentrations in different times, then QBC939 cells were harvested and investigated. Cell growth inhibition was evaluated by MTT assay, cell quantification and colony-forming test. The morphologic changes were estimated by fluorescence-microscope and electronic microscope, cell cycle changes of QBC939 cell line induced by nimesulide were measured by means of flow cytometry, DNA ladder to assay the DNA degradation, RT-PCR technique was used to investigate the transcriptional changes of gene bcl-2/ bax/survivin. Furthermore, immunocytochemistry was used to examine the changes of their protein expression.Results (1) Expression of COX-2 can be detected in the human chalangiocarcinaQBC939 cell line, after expoure to 200 u mol/L nimesulide 48h,the expression of COX-2 protein decreased markedly. (2) The growth inhibition of QBC939 cell line...
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