AIM:To evaluate the roles and mechanisms of celecoxib ininducing proliferation inhibition and apoptosis of humancholangiocarcinoma cell lines.METHODS:Cyclooxygenase-2-overexpressing humancholangiocarcinoma cell line QBC939 and cyclooxygenase-2-deficient human cholangiocarcinoma cell line SK-CHA-1were used in the present study.The anti-proliferative effectwas measured by methabenzthiazuron (MTT) assay;apoptosis was determined by transferase-mediated dUTPnick end labeling (TUNEL) detection and transmissionelectron microscopy (TEM).Cell cycle was analyzed by flowcytometry (FCM).The PGE_2 levels in the supernatant ofcultured cholangiocarcinoma cells were quantitated byenzyme-linked immunoabsordent assay (ELISA).RESULTS:Celecoxib suppressed the production of PGE_2and inhibited the growth of QBC939 cells.Celecoxib at 10,20,and 40 μmol/L inhibited PGE_2 production by 26 %,58 %,and 74 % in QBC939 cells.The PGE_2 level wasmuch lower constitutively in SK-CHA-1 cells (18.6±3.2)compared with that in QBC939 (121.9±5.6) cells (P<0.01)and celecoxib had no significant influence on PGE_2 level inthe SK-CHA-1 cells.The PGE_2 concentration in SK-CHA-1cells also reduced but not significantly after treatment withcelecoxib.The PGE_2 concentration in SK-CHA-1 cells was(16.5±2.9) ng/well,(14.8±3.4) ng/well,(13.2±2.0) ng/welland (12.6±3.1) ng/well respectively,when pre-treated with1 μmol/L,10 μmol/L,20 μmol/L and 40 μmol/L of celecoxibfor 48 h (P>0.05,vscontrol).The anti-proliferation effect ofcelecoxib (20 μmol/L) on QBC939 cells was time-dependent,it was noticeable on day 2 (OD490=0.23±0.04) and becameobvious on day 3 (OD490=0.31±0.07) to day 4 (OD490=0.25±0.06),and the OD490 in the control group (day 1)was 0.12±0.03 (P<0.01,vs control).The anti-proliferationeffect of celecoxib could be abolished by the addition of200 pg/mL PGE_2.The proliferation of SK-CHA-1 cells wasinhibited slightly by celecoxib,the cell density OD490 inthe presence of celecoxib and in control group was 0.31±0.04 and 0.42±0.03 respectively on day 2 (P>0.05),0.58±0.07 and 0.67±0.09 respectively on day 3 (P>0.05),and 0.71±0.08 and 0.78±0.06 respectively on day 4 (P>0.05).Celecoxibinduced proliferation inhibition and apoptosis by G_1-S cellcycle arrest:the percentage of QBC939 cells in G_0-G_1 phaseafter treatment with 40 μmol/L (74.66±6.21) and 20 pmol/L (68.63±4.36) celecoxib increased significantly compared with control cells (54.41±5.12,P<0.01).The percentageof SK-CHA-1 cells in G_0-G_1 phase after treatment with variousconcentrations of celecoxib didn’t change significantlycompared with control cells.The TUNEL index was muchhigher in QBC939 cells treated with 20 μmol/L celecoxibfor 2 d (0.063±0.018) and for 4 d (0.102±0.037) comparedwith control cells (0.017±0.004,P<0.01).CONCLUSION:The current in vitro study indicates thatinhibition of proliferation and induction of apoptosis in humancholangiocarcinoma cells by cyclooxygenase-2 specificinhibitor celecoxib may involve in COX-dependent mechanismsand PGE_2 pathway.Celecoxib as a chemopreventive andchemotherapeutic agent might be effective primarily on COX-2-expressing cholangiocarcinoma. AIM: To evaluate the roles and mechanisms of celecoxib in inducing proliferation inhibition and apoptosis of human cholangiocarcinoma cell lines. METHODS: Cyclooxygenase-2-overexpressing human cholangiocarcinoma cell line QBC939 and cyclooxygenase-2-deficient human cholangiocarcinoma cell line SK-CHA-1were used in the present study. The anti-proliferative effect was measured by methabenzthiazuron (MTT) assay; apoptosis was determined by transferase-mediated dUTPnick end labeling (TUNEL) detection and transmission electron microscopy (TEM). Cell cycle was analyzed by flowcytometry (FCM). The PGE_2 levels in the supernatant of culture cholangiocarcinoma cells were quantitated by enzyme-linked immunoabsordent assay (ELISA) .RESULTS: Celecoxib suppressed the production of PGE_2and inhibited the growth of QBC939 cells. Celecoxib at 10,20, and 40 μmol / L inhibited PGE_2 production by 26%, 58 %, and 74% in QBC939 cells. PGE_2 level wasmuch lower constitutively in SK-CHA-1 cells (18.6 ± 3.2) compared with tha (P <0.01) and celecoxib had no significant influence on PGE_2 level inthe SK-CHA-1 cells. PGE_2 concentration in SK-CHA-1 cells also reduced but not significantly after treatment with celecoxib. PGE_2 concentration in SK-CHA-1cells was (16.5 ± 2.9) ng / well, (14.8 ± 3.4) ng / well and (13.2 ± 2.0) ng / welland with 1 μmol / L, 10 μmol / L, 20 μmol / L and 40 μmol / L of celecoxib for 48 h (P> 0.05 vs vs control). The anti-proliferation effect of actlecoxib , it was noticeable on day 2 (OD490 = 0.23 ± 0.04) and became clear on day 3 (OD490 = 0.31 ± 0.07) to day 4 (OD490 = 0.25 ± 0.06), and the OD490 in the control group ± 0.03 (P <0.01, vs control). The anti-proliferation effect of celecoxib could be abolished by the addition of 200 pg / mL PGE_2. The proliferation of SK-CHA-1 cells was inhibited slightly by celecoxib, the cell density OD490 inthe presence of celecoxib and in control group wa s 0.31 ± 0.04 and0.42 ± 0.03 respectively on day 2 (P> 0.05), 0.58 ± 0.07 and 0.67 ± 0.09 respectively on day 3 (P> 0.05), and 0.71 ± 0.08 and 0.78 ± 0.06 respectively on day 4 (P> 0.05) .Celecoxibinduced proliferation inhibition and apoptosis by G_1-S cellcycle arrest: the percentage of QBC939 cells in G_0-G_1 phase after treatment with 40 μmol / L (74.66 ± 6.21) and 20 pmol / L (68.63 ± 4.36) celecoxib increased significantly with control cells ± 5.12, P <0.01). The percentage of SK-CHA-1 cells in G_0-G_1 phase after treatment with various concentrations of celecoxib did not change significantly with modulated cells. TUNEL index was muchhigher in QBC939 cells treated with 20 μmol / L CONCLUSION: The current in vitro study indicates that inhibition of proliferation and induction of apoptosis in human cholangiocarcinoma cells by cyclooxygenase (0.063 ± 0.018) and for 4 d (0.102 ± 0.037) compared with control cells (0.017 ± 0.004, P <0.01) -2 specificinhibitor celecoxib may involve in COX-dependen t mechanisms and PGE_2 pathway. Celecoxib as a chemopreventive and chemotherapeutic agent might be acting on COX-2-expressing cholangiocarcinoma.