Celecoxib ; Cell Proliferation ; drug effects ; Drug Resistance, Multiple ; Humans ; Interferon-alpha ; pharmacology ; K562 Cells ; Pyrazoles ; pharmacology ; Sulfonamides ; pharmacology

Cyclooxygenase 2 ; metabolism ; Cyclooxygenase Inhibitors ; pharmacology ; Hep G2 Cells ; Humans ; Nitrobenzenes ; pharmacology ; Radiation Tolerance ; drug effects ; Sulfonamides ; pharmacology

OBJECTIVETo investigate anticancer effect and molecular mechanism of N-[(Cyclohexyloxy)-4-nitrophenyl] methanesulfonamide on HepG2 cells in vitro.

METHODSHepG2 cells were treated with various concentrations (100, 200, 300, 400 micromol/L) of NS-398 [selective for cyclooxygenase 2 (COX-2) inhibition]. Cell growth was measured by MTT method, DNA fragmentation gel analysis was used to analyze the apoptosis cells, DNA ploidy and apoptotic cell percentage were examined by flow cytometry (FCM). PGE2 concentration was measured by radioimmunoassay method. The expressions of COX-2 were also examined by Western blot analysis.

RESULTSNS-398 inhibited HepG2 cell proliferation and induced apoptosis in a concentration-dependent manner. DNA ploidy analysis showed that S phase cells were significantly decreased and quiescent G1 phase was accumulated with NS-398 concentration increasing. The IC50 of 24 hours was 300 micromol/L. The release of PGE2 was significantly reduced in HepG2 cells with the values of NS-398 being (0.70 +/- 0.02), (0.48 +/- 0.02), (0.29 +/- 0.01) and (0.18 +/- 0.01) respectively, as compared with control group (0.03 +/- 0.01). NS-398 could inhibit the activity and expression of COX-2, with higher concentration, it can significantly down-regulate the expression of COX-2 (t = 3.736, 1.623, 1.810, 2.587, P < 0.01).

CONCLUSIONNS-398 might significantly inhibit the proliferation of HepG2 cells and induce apoptosis. The mechanisms were related with the accumulation of quiescent G1 phase and the inhibition of COX-2 activity.

Apoptosis ; drug effects ; Cell Line, Tumor ; metabolism ; Cell Proliferation ; drug effects ; Cyclooxygenase 2 ; biosynthesis ; Humans ; Nitrobenzenes ; pharmacology ; Sulfonamides ; pharmacology

OBJECTIVETo observe the electrophysiological effects of ibutilide on canine and to explore the potential mechanisms of ibutilide on terminating atrial flutter.

METHODSEighteen mongrel dogs were anesthetized and intubated. The heart was exposed through thoracotomy for electrodes implantation. The electrophysiologic variables (heart rate, the conduction of intraatrium and interatrium, the conduction ratio of isthmus, the effective refractory period) were measured in the absence or presence of ibutilide (10 minute infusion with 0.10 mg/kg ibutilide, 30 minutes later with a maintaining dose of 0.01 mg/min).

RESULTSIbutilide significant suppressed sinus atrial node function, the peak effect was observed at 20 - 30 min post drug infusion and heart rate returned to normal at 2 hours post infusion. Post ibutilide infusion, 1 canine developed sinus pause for 5 seconds and 2:1 atrioventricular conduction block was evidenced in another canine. The atrial, ventricular and pulmonary vein effective refractory periods were all significant prolonged (all P < 0.05) post ibutilide infusion. However, conduction of intraatrium, interatrium and isthmus remained unchanged post ibutilide infusion (all P > 0.05).

CONCLUSIONSIbutilide could suppress sinus atrial node and the atrioventricular node function. The mechanism of ibutilide on rapidly terminating atrial flutter might be related to the prolongation of the refractory periods which might then result in the reduction of the whole excitable gap of the reentrant circuit and induce proceed inability of reentrant wavefront.

Animals ; Anti-Arrhythmia Agents ; pharmacology ; Atrial Flutter ; drug therapy ; physiopathology ; Dogs ; Heart Rate ; drug effects ; Male ; Sulfonamides ; pharmacology

The effects of acute cooling/rewarming on cardiac K(+) currents and membrane potential were investigated. Membrane potential and current were assessed with whole-cell patch-clamp technique in current- and voltage-clamp modes. When the temperature of bath solution was decreased from 25 °C; to 4 °C, the transient outward current (I(to)) was completely abolished, the sustained outward K(+) current (I(ss)) at +60 mV and the inward rectifier K(+) current (I(K1)) at -120 mV were depressed by (48.5±14.1)% and (35.7±18.2)%, respectively, and the membrane potential became more positive. After the temperature of bath solution was raised from 4 °C; to 36 °C;, the membrane potential exhibited a transient hyperpolarization and then was maintained at a stable level. In some myocytes (36 out of 58), activation of the ATP-sensitive K(+) (K(ATP)) channels after rewarming was observed. The rewarming-induced change in the membrane potential was inhibited by the Na(+)/K(+)-ATPase inhibitor ouabain (100 μmol/L), and the rewarming-elicited activation of K(ATP) channels was inhibited by the protein kinase A inhibitor H-89 (100 μmol/L). Moreover, decrease of the temperature from 25 °C; to 4 °C; did not induce any significant change in cell volume when the cell membrane potential was clamped at 0 mV. However, significant cell shrinkage with spots was observed soon after rewarming-induced activation of K(ATP) channels. These data demonstrate that acute cooling/rewarming has a profound influence on the membrane potential and K(+) currents of ventricular myocytes, and suggest that activation of K(ATP) channels may play a role in cardiac cooling/rewarming injury.
Animals ; Cold Temperature ; Isoquinolines ; pharmacology ; KATP Channels ; metabolism ; Membrane Potentials ; Myocytes, Cardiac ; physiology ; Patch-Clamp Techniques ; Rats ; Rewarming ; Sulfonamides ; pharmacology

OBJECTIVETo investigate the effects of various HIV protease inhibitors on the function of pancreatic beta-cells.

METHODSRat insulinoma INS-1 cells were incubated with different concentrations of ritonavir or amprenavir for 48 h and stimulated with 20 mmol/L D-glucose for 30 min. The rate of insulin release was measured in the supernatant by ELISA, normalized to cellular DNA contents. Cells were counted with trypan blue and MTT test were determined to evaluate the effect of protease inhibitors on cell viability.

RESULTRitonavir treatment significantly decreased baseline insulin release and glucose-stimulated insulin release in a dose-dependent manner (r=-0.861, -0.839, both P<0.01). For 10 micromol/L of ritonavir, the decrease rate of baseline insulin secretion and glucose-stimulated insulin secretion was 46% and 47%, respectively. Amprenavir had no effect on the rate of insulin release.

CONCLUSIONVarious HIV protease inhibitors present different effect on the insulin release of pancreatic beta-cells.

Animals ; Carbamates ; pharmacology ; HIV Protease Inhibitors ; pharmacology ; Insulin ; secretion ; Insulinoma ; metabolism ; pathology ; Islets of Langerhans ; metabolism ; Pancreatic Neoplasms ; metabolism ; pathology ; Rats ; Ritonavir ; pharmacology ; Sulfonamides ; pharmacology

OBJECTIVE: To investigate the effect and mechanism of the selective COX-2 inhibitor NS-398 and carboplatin on the human cervical carcinoma cell line Hela. METHODS: The effect of NS-398, carboplatin, and both on the proliferation of Hela cells was assessed by methyl-thiazolyl tetrazolium (MTT) method, and the apoptosis assay and cell cycle distribution were analyzed by flow cytometry. RESULTS: NS-398, and carboplatin inhibited the growth of Hela cells in a dose and time-dependent manner. When combining carboplatin with NS-398, the combined inhibition rate was increased, which nearly equaled the inhibition rate of the double concentrations of carboplatin. Flow cytometry demonstrated that the cell cycle was redistributed: the G(1)-phase cell fraction was increased while the S-phase cell fraction was significantly decreased after the cells were treated with NS-398 (P<0.05), However,the result was just the opposite after being treated with carboplatin. The apoptotic rate was 1.48%+/-0.03% and 3.43%+/-0.02% for pre-treatment and post-treatment with NS-398 respectively (P>0.05) while the apoptotic rate was 9.32%+/-0.02% after the treatment with carboplatin (P<0.05). CONCLUSION NS-398 can inhibit the growth of Hela cells. The effect of NS-398 on Hela cells may not be related to the apoptosis. NS-398 and carboplatin can bring about synergistic effect in chemotherapy on Hela cells.
Apoptosis ; drug effects ; Carboplatin ; pharmacology ; Cell Proliferation ; drug effects ; Cyclooxygenase 2 Inhibitors ; pharmacology ; Drug Synergism ; HeLa Cells ; Humans ; Nitrobenzenes ; pharmacology ; Sulfonamides ; pharmacology

The inhibitory effects of two kinds of selective cyclooxygenase-2 inhibitors on the proliferation of human carcinoma of larynx Hep-2 in vitro and their corresponding mechanisms were investigated. Hep-2 cells were cultured with two kinds of selective cyclooxygenase-2 inhibitors (Sc-58125 and Celecoxib) at various concentrations for 24 h. Morphological changes were observed under the phase microscopy and the growth suppression was detected by using MTT colorimetric assay. Apoptotic DNA fragments were observed by agarose gel electrophoresis, and the cell cycle and apoptotic rate were detected by flow cytometry (FCM) respectively. Hep-2 cells became rounded and detached from the culture dish after being treated with Celecoxib for 24 h, however, they remained morphologically unchanged with Sc-58125. Sc-58125 could increase G2 phase cells, whereas, Celecoxib rose G1 phase cells. Both of the two effects were dose-dependent. Moreover, the Hep-2 cells cultured with 50 micromol/L and 100 micromol/L Celecoxib showed obvious apoptosis, with the nuclear DNA of cells exhibiting characteristic DNA ladder. So Sc-58125 could inhibit the proliferation of Hep-2 cells by altering the G2 phase cells. However, Celecoxib had the same effect by changing the G1 phase cells and inducing apoptosis at higher concentration.
Antineoplastic Agents/pharmacology ; Apoptosis/drug effects ; Cell Proliferation/drug effects ; Cyclooxygenase 2 Inhibitors/*pharmacology ; Dose-Response Relationship, Drug ; Laryngeal Neoplasms/*pathology ; Pyrazoles/*pharmacology ; Sulfonamides/*pharmacology ; Tumor Cells, Cultured

OBJECTIVETo study the effects of NS398, a selective cyclooxygenase-2 (COX-2) inhibitor, on the transcription and translation of BCL-3 and its regulatory gene cyclin D1 in colon cancer cell line SW480.

METHODSHuman colon cancer cells SW480 were divided into two groups: SW480 cells in experimental group were treated with NS398 in different concentrations(25 micromol/L, 50 micromol/L, 100 micromol/L and 200 micromol/L) for 48 h or 72 h. SW480 cells in control group were treated with media which did not contain NS398. Then the expressions of BCL-3 and cyclin D1 were detected by RT-PCR, Western blot, and immunocytochemistry.

RESULTSAt 48 hours RT-PCR showed that BCL-3 mRNA and cyclin D1 mRNA decreased in a dose-dependent manner in the experimental group. However, there were no significant differences in the levels of BCL-3 protein and cyclin D1 protein between two groups (P>0.05). At 72 hours, BCL-3 protein and cyclin D1 protein also decreased in a dose-dependent manner in the experimental group. When the concentration of NS398 reached 100 micromol/L, the differences between the two groups in the expression of BCL-3 mRNA and protein became statistically significant (P<0.01). When the concentration of NS398 reached 50 micromol/L, the differences in the expression of cyclin D1 mRNA and protein were statistically significant (P<0.05).

CONCLUSIONSBCL-3 is expressed in colon cancer cell line SW480. COX-2 inhibitor can inhibit the expression of BCL-3 and cyclin D1 in a dose-dependent manner. NS398 may down-regulate the expression of cyclin D1 through BCL-3.

Cell Line, Tumor ; drug effects ; Colonic Neoplasms ; metabolism ; Cyclin D1 ; metabolism ; Cyclooxygenase 2 Inhibitors ; pharmacology ; Humans ; Nitrobenzenes ; pharmacology ; Proto-Oncogene Proteins ; metabolism ; Sulfonamides ; pharmacology ; Transcription Factors ; metabolism

Carcinoma, Hepatocellular ; pathology ; Cell Cycle ; drug effects ; Cell Proliferation ; drug effects ; Cyclooxygenase 2 Inhibitors ; pharmacology ; Humans ; Liver Neoplasms ; pathology ; Nitrobenzenes ; pharmacology ; Sulfonamides ; pharmacology ; Tumor Cells, Cultured