OBJECTIVETo evaluate the chemopreventive effect of celecoxib, a specific cyclooxegenease-2 (COX-2) inhibitor, on chemically induced breast cancer of rats and its effect on COX-2 expression.

METHODS7, 12-dimethylbenz anthracene (DMBA) was administered intragastrically in SD female rats to establish breast cancer models, which were divided subsequently into control group, tamoxifen group and celecoxib group to receive different treatments accordingly. The occurrence rate of breast cancer was observed and the effect of celecoxib on COX-2 and vascular endothelial growth factor (VEGF) expressions assayed by immunohistochemical SP method.

RESULTSThe incidence of breast cancer in tamoxifen group (48.15%) and celecoxib group (50.00%) were both significantly lower than that in the control group (85.71%; P=0.003 and P=0.004, respectively). The positivity rate of COX-2 expression in celecoxib group (28.57%) was significantly lower than those of tamoxifen group (48.15%) and control group (83.33%; P=0.001 and P=0.035, respectively). The positivity rate of VEGF expression in celecoxib group (42.86%) was significantly lower than that of control group (79.17%, P=0.023), but comparable with that in tamoxifen group (46.15%, P=0.863).

CONCLUSIONCelecoxib can significantly suppress DMBA-induced breast cancer in female rats possibly through down-regulation of COX-2 and VEGF expressions.

9,10-Dimethyl-1,2-benzanthracene ; Animals ; Celecoxib ; Cyclooxygenase 2 ; metabolism ; Cyclooxygenase Inhibitors ; therapeutic use ; Down-Regulation ; drug effects ; Female ; Immunohistochemistry ; Mammary Neoplasms, Experimental ; chemically induced ; metabolism ; prevention & control ; Pyrazoles ; therapeutic use ; Rats ; Rats, Sprague-Dawley ; Sulfonamides ; therapeutic use ; Tamoxifen ; therapeutic use ; Treatment Outcome ; Vascular Endothelial Growth Factor A ; metabolism

OBJECTIVETo study the effect of nimesulide (NIM) on the tumorigenesis of mammary tumors induced by dimethylbenzoic acid (DMBA), and to investigate possible mechanisms of NIM against tumors.

METHODSThe studied rats were randomly divided into four groups: experimental control group, NIM group, diet and drug of NIM control group. The incidence of mammary tumor was observed. RT-PCR, Western blot were used to detect 8 cancerous tissues in every group, randomly. The expressions of cylooxygenase-2 (COX-2) were assessed by immunohistochemistry. The levels of prostaglandin E(2) (PGE(2)) in blood plasma and tumor tissues were determined by means of radio-immunity assay. The apoptosis index and the proliferation index were evaluated by TUNEL assay, immunohistochemical staining for proliferating cell nuclear antigen (PCNA), respectively.

RESULTSThe incidence of mammary tumor was 69.2% in experimental control group, 40.3% in NIM group. There was obviously decreased incidence in NIM group; The expressions of COX-2 mRNA and protein were significantly down-regulated in NIM group compared with experimental control group. The increased levels of PGE(2) synthesis in blood plasma and tumor tissues were significantly decreased by administering NIM (P < 0.05). The apoptosis index was obviously higher, the proliferation index was markedly less in NIM group than experimental control group.

CONCLUSIONSNimesulide could inhibit the tumorigenesis and development of DMBA-induced mammary tumors by inhibition of proliferation and induction of apoptosis. COX-2 and COX-2-mediated PGE(2) synthesis may play an important role in rat DMBA-induced breast cancer.

9,10-Dimethyl-1,2-benzanthracene ; Animals ; Apoptosis ; drug effects ; Cyclooxygenase 2 Inhibitors ; pharmacology ; Dinoprostone ; metabolism ; Female ; Mammary Neoplasms, Experimental ; chemically induced ; metabolism ; prevention & control ; Random Allocation ; Rats ; Rats, Wistar ; Sulfonamides ; pharmacology

OBJECTIVEThe chemopreventive activity and mechanism of dehydroepiandrosterone (DHEA) were studied.

METHODSModel of 7, 12-dimethylbenz (alpha) anthracene (DMBA) induced breast carcinoma in Sprague-Dawley rats, uitra-violet (UV)-induced DNA damage and Salmonella mutation assay were used.

RESULTSIn DMBA-induced rat mammary tumor model, the rats were orally given daily DHEA for 2 weeks before DMBA and continued for 10 weeks after DMBA administration. The results showed significant inhibition of tumor development by DHEA. The incidence of mammary carcinoma also decreased significantly on daily dose of oral 25 mg/kg DHEA with the mean tumor volume per rat also remarkably reduced by 92%. Moreover, 25 mg/kg DHEA treatment could significantly increase the carcinoma latency for about 3.5 weeks as compared with the control. Using polymerase chain reaction (PCR) assay, in vitro 10(-9) mol/L DHEA showed significant inhibitory effect on UV-induced DNA damage by 90%. In Ames test, DHEA was found to decrease DMBA and benzo (alpha) pyrene-induced TA98 and TA100 His(+) revertants markedly and the number of Salmonella clones were significantly reduced by 53.2% and 73.0% on dose of 5 microgram DHEA/plate. It was also shown that in vitro 10(-7) mol/L DHEA could also effectively inhibit the G-6-PDH activity, which might play an important role in its chemoprophylaxis activities.

CONCLUSIONThe results strongly prove that DHEA is a potent cancer chemoprophylaxis agent, which exhibits inhibitory potential on mutation and chemical carcinogen in vivo and in vitro.

9,10-Dimethyl-1,2-benzanthracene ; administration & dosage ; Adjuvants, Immunologic ; pharmacology ; Animals ; Antimutagenic Agents ; pharmacology ; DNA Damage ; drug effects ; Dehydroepiandrosterone ; pharmacology ; Disease Models, Animal ; Dose-Response Relationship, Drug ; Glucosephosphate Dehydrogenase ; antagonists & inhibitors ; metabolism ; Mammary Neoplasms, Experimental ; chemically induced ; prevention & control ; Mutagenicity Tests ; Rats ; Rats, Sprague-Dawley ; Salmonella ; drug effects ; genetics ; Time Factors ; Tumor Cells, Cultured

The anticarcinogenic effects and mechanisms of the biotechnological drugs of Panax ginseng C.A. Meyer cultivated in Russia, bioginseng, panaxel and panaxel- 5, were studied. Bioginseng was produced from a tissue culture of ginseng root cultured on standard medium, whereas panaxel and panaxel-5 were produced from ginseng tissue root cultures using standard mediums enriched with 2-carboxyethylgermanium sesquioxide and 1-hydroxygermatran-monohydrate respectively. All three ginseng drugs inhibited the development of mammary tumors induced by intramammary injections of N-methyl-N-nitrosourea (MNU) in rats, the development of the brain and spinal cord tumors induced by transplacental administration of N-ethyl-N-nitrosourea (ENU) in rats, and the development of uterine, cervical and vaginal tumors induced by intravaginal applications of 7,12-dimethylbenz(a)anthracene (DMBA) in mice. The ginseng drugs induced the cytotoxic activity of macrophages in mice, enhanced T-lymphocyte rosette formation in guinea pigs exposed to cyclophosphamide, and stimulated the production of thyroid hormones in rats. These mechanisms may contribute to the anticarcinogenic action of the ginseng drugs. The organic germanium compounds present in panaxel and panaxel-5 did not potentiate the anticarcinogenic or immuno- stimulatory effects as much as biogeinseng. Preliminary clinical trials with panaxel and bioginseng were carried out in patients with precancerous lesions of the esophagus and endometrium. Panaxel was found to have a strong therapeutic effect in patients suffering from chronic erosive esophagitis. Bioginseng induced the regression of adenomatous-cystic hyperplasia of the endometrium in some patients. Thus, we conclude that the drugs of ginseng appear to hold considerable promise for future cancer chemoprevention.
Adenocarcinoma/chemically induced/prevention & control ; Adult ; Animal ; Antineoplastic Agents, Phytogenic/*therapeutic use ; Cells, Cultured ; Cervix Neoplasms/chemically induced/prevention & control ; Clinical Trials ; Cytotoxicity Tests, Immunologic ; Disease Models, Animal ; Endometrial Neoplasms/pathology/prevention & control ; Endometrium/pathology ; Esophageal Neoplasms/pathology/prevention & control ; Esophagus/pathology ; Estradiol/blood ; Female ; Fibroadenoma/chemically induced/prevention & control ; Human ; Macrophages, Peritoneal/cytology/immunology ; Male ; Mammary Neoplasms, Experimental/chemically induced/prevention & control ; Mice ; Mice, Inbred C57BL ; Neoplasms, Experimental/chemically induced/*prevention & control ; Nervous System Neoplasms/chemically induced/prevention & control ; Panax/*metabolism ; Precancerous Conditions/pathology/*prevention & control ; Rats ; Tissue Culture ; Uterine Neoplasms/chemically induced/prevention & control ; Vaginal Neoplasms/chemically induced/prevention & control