Inactivation of the CDKN2 gene by homozygous deletion and de novo methylation is associated with advanced stage esophageal squamous cell carcinoma

We examined the genomic status of the CDKN2 gene including de novo methylation of 5' CpG islands in primary and metastatic tumor samples from 31 patients with esophageal squamous cell carcinoma. One somatic frame shift mutation (1 of 31; 3.2%) was identified by PCR-single strand conformational polymorphism analysis and DNA sequencing. Homozygous deletion and de novo methylation of the gene were confirmed in 5 (16%) and 6 (19%) of 31 patients, respectively. Homozygous deletion and de novo methylation were significantly associated with silencing of gene expression (P < 0.01). Aberrations of the CDKN2 gene were detected in tumors with lymph node metastasis and muscular invasion (12 of 22; 54%) and in none of stage I tumors (0 of 9.0%; P < 0.05). These results suggest that homozygous deletion and de novo methylation are predominant mechanisms of inactivation of the CDKN2 gene and may be associated with metastatic and invasive phenotypes of esophageal squamous cell carcinoma.

Allogeneic hepatocyte and fetal liver transplantation and xenogeneic hepatocyte transplantation for Nagase's analbuminemic rats

Allogeneic hepatocyte and fetal liver transplantation and xenogeneic hepatocyte transplantation were performed in Nagase's analbuminemic (NAR, RT1(1)) rats, and the functional and morphological changes of intrasplenic grafts under FK506 immunosuppression were examined. Normal male Wistar Shi rats (RT1k) and male BALB/C mice were used as donors. Serum albumin levels in FK506-treated NAR rats 4 wk after all three transplantation techniques performed were significantly higher than those in animals without immunosuppression, indicating the intrasplenic grafts had survived in FK506-treated groups. On histological examination, hepatocyte colonies were detected in FK506-treated rats after allogeneic hepatocyte or fetal liver transplantation. NAR rats are expected to be useful for studies on allogeneic or xenogeneic hepatocyte transplantation under immunosuppression by various methods.

Antimicrobial activity of superoxidized water

We tested the antimicrobial activity of superoxidized water against methicillin-sensitive Staphylococcus aureus, methicillin-resistant Staphylococcus aureus, Staphylococcus epidermidis, Serratia marcescens, Escherichia coli, Pseudomonas aeruginosa and Burkholderia cepacia. The number of bacteria was reduced below detection limit following incubation in superoxidized water for 10 s. The bactericidal activity of superoxidized water was similar to that of 80% ethanol, but superior to that of 0.1% chlorhexidine and 0.02% povidone iodine. We conclude that superoxidized water is a low cost but powerful disinfectant.

Evaluation of a novel osteogenic factor, bone cell stimulating substance, in a rabbit cranial defect model

A novel osteogenic factor, bone cell stimulating substance (BCSS), was recently isolated from bovine bone. Unlike the bone morphogenetic proteins, which are generally 20- to 40-kDa glycoproteins belonging to the transforming growth factor-beta superfamily, BCSS is a 2.5-kDa, water-soluble polypeptide. This study evaluated the osteogenic potential of BCSS in combination with coralline-derived porous hydroxyapatite to reconstruct a large, nonhealing cranial defect in the rabbit. Twenty-four rabbits underwent a 16 x 20 mm full-thickness (extradural) excision of the parietal bones and were divided into six groups of four rabbits each. Group 1 through 5 were reconstructed with 16 x 20 x 1.5 mm hydroxyapatite implants treated with: (1) 20 osteogenic units (424 micrograms) BCSS, (2) 8 osteogenic units (170 micrograms) BCSS, (3) 4 osteogenic units (85 micrograms) BCSS, (4) 0 osteogenic units (424 micrograms) inactive BCSS analog, or (5) left untreated. Group 6 was left unreconstructed. Implants were harvested at 12 weeks and analyzed for percentage of lamellar bone formation by a computerized microscope video image analysis system. Groups reconstructed with BCSS-treated hydroxyapatite implants demonstrated more bone ingrowth than did the control hydroxyapatite groups not treated with BCSS (inactive BCSS analog or untreated). Linear regression dose-response analysis indicated an average 3.2 percent increase in bone ingrowth for a 10-U increase in BCSS (p = 0.043). The unreconstructed control group demonstrated no healing. With a molecular mass of only 2.5 kDa and its identity not completely known, BCSS is a novel factor that seems to possess osteogenic potential similar to that of previously investigated osteogenic proteins.

Pharmaceutical studies for gene therapy: expression of human Cu, Zn-superoxide dismutase gene transfected by lipofection in rat skin fibroblasts

To evaluate whether lipofection using Lipofectin is suitable for delivering foreign genes into skin fibroblasts as target cells, we performed experiments using human superoxide dismutase (hSOD) and neomycin-resistance (Neo) genes as models in rat skin fibroblasts (FR and primary cells) in vitro. The amounts of DNA used in the lipofection procedure significantly affected the transfection efficiencies, and the optimal amounts were determined for all cells used. However, the efficiencies in rat skin fibroblasts were about 20-fold higher than that in rat lung epithelial-like cells (L2 cells). The differences in plasmid vectors (pRc/RSV-SOD and pRc/CMV-SOD) hardly affected the transfection efficiencies. The amounts of Lipofectin significantly affected the transfection efficiencies, and the optimal amounts were determined for both types of skin fibroblasts. However, cytotoxic effects in both skin fibroblasts were observed with high doses of Lipofectin. On the other hand, with optimal amounts of DNA and Lipofectin, the reporter gene (NeoT) introduced into cells was mainly integrated into the host cell chromosome. Western blot analysis showed the continuous expression of hSOD protein for at least 45 d in skin fibroblasts transfected with the expression plasmid for hSOD by Lipofectin under the optimal conditions, and the cellular SOD activity fluctuated in parallel with the expression of hSOD protein. Differences in the type of cells also affected the expression of hSOD. These results indicate that it is necessary to set up optimal conditions for transfection using Lipofectin for each cell type, and that transfection with Lipofectin under optimal conditions may be an efficient method for introduction of foreign genes into skin fibroblasts for use as a clinical delivery system of therapeutic protein.

Cytolytic activity induced by intramuscular injection of plasmid DNA expressing the nucleocapsid protein of the JHM strain of mouse hepatitis virus into C57BL/6 mice

We constructed plasmids expressing mRNA7 coding the nucleocapsid (N) protein of JHM strain of MHV (JHMV) under the control of Rous sarcoma virus (RSV) LTR or human elongation factor (EF) 1a promoter, referred to as pRSV-mRNA7 and pEF-mRNA7, respectively. Although only a slight level of cytolysis was observed by the spleen cells from C57BL/6 mice injected intramuscularly with pEF-mRNA7, the spleen cells from the mice administered with pRSV-mRNA7 showed a significant level of cytolytic activities against the cells expressing the viral N protein. The difference in the level of specific cytolysis might have been mainly due to a difference in the expression levels of the N protein in the muscles between the mice injected with pEF-mRNA7 and pRSV-mRNA7, since the specific activity of chloramphenicol acetyltransferase (CAT) in muscles from the mice injected with plasmid DNA expressing CAT gene directed by RSV LTR was significantly higher than that in those administered by the plasmid DNA directed by EF-1a promoter.

The largest isoform of platelet membrane glycoprotein Ib alpha is commonly distributed in eastern Asian populations

Platelet membrane glycoprotein Ib alpha has at least two polymorphisms which affect phenotype. One is the dimorphism at codon 145, and the other is a molecular weight polymorphism due to variable numbers of tandem repeats (TR) in the macroglycopeptide region. These two polymorphisms are in linkage disequilibrium. The frequencies of these polymorphisms differ considerably depending on race, and the largest variant with four TR is almost exclusively present in the Japanese population. We examined the genotypes of HPA-2 and TR polymorphism in three different races from Eastern Asia; the Japanese (n = 103), Korean (n = 101) and Chinese population (n = 177). The gene frequency of HPA-2 differed significantly among these three populations. Among HPA-2b-positive individuals, the A isoform with four TR and B with three TR were present in all three populations and A dominated over B. Individuals homozygous for the A isoform were found in both Japanese and Korean populations. These findings indicate that the largest haplotype is common in the Eastern Asian region.

Transforming growth factor-beta, osteogenin, and bone morphogenetic protein-2 inhibit intercellular communication and alter cell proliferation in MC3T3-E1 cells

Intercellular communication by gap junctions has been implicated to function in the control of cell growth and differentiation in osseous tissues-processes which are regulated, in part, by peptide growth factors, including transforming growth factor-beta (TGF-beta) and the bone morphogenetic proteins (BMPs). Using the osteoblastic cell line MC3T3-E1, we tested the hypothesis that the effects of TGF-beta and BMPs on cell proliferation may be correlated to changes in intercellular communication. In a series of proliferation assays, MC3T3-E1 cells were cultured in the presence of bone morphogenetic protein-2 (BMP-2) or TGF-beta for up to 48 hr. Proliferation of cells during the linear log phase (days 2 to 4) was assessed by 3H-thymidine (3H-TdR) incorporation. After times ranging from 6 to 48 hr, BMP-2 significantly inhibited uptake of 3H-TdR at doses of 50-800 ng/ml. Similarly, TGF-beta inhibited uptake of 3H-TdR at doses of 2-32 ng/ml. In a separate group of experiments, intercellular communication through gap junctions was demonstrated by cell-cell transfer of the fluorescent tracer, lucifer yellow, after microinjection. One series of experiments showed that the gap junctional intercellular communication (GJIC) of cells, incubated for 48 hr in the presence of the higher dose of osteogenin (OG) (5.0 vs. 0.5 microgram/ml) or higher dose of TGF-beta (2.0 vs. 0.2 ng/ml), was significantly inhibited compared to control. In another series of experiments, time and dose dependent effects of BMP-2 and TGF-beta on GJIC were investigated. In the time course experiments (3, 6, 12, 24, and 48 hr), TGF-beta (2.0 ng/ml) demonstrated a statistically significant effect in inhibiting GJIC as early as 6 hr, while BMP-2 (50 ng/ml) inhibited GJIC after 24 and 48 hr of treatment. The dose-dependent effects of BMP-2 and TGF-beta on cell couplings, determined at 48 hr, showed significant inhibitory effects with BMP-2 at 25 and 50 ng/ml and with TGF-beta at 2 and 4 ng/ml. The cell count results and injection study performed at 12 hr, at a fixed cell density, confirmed that the inhibitory effect was not due to differences in cell density. The 50% effective inhibitory concentrations (EC50) calculated for BMP-2 and TGF-beta at 48 hr, showed no dose correlation between proliferation and GJIC, suggesting that these two events are independent occurrences. Additionally, marked morphological change was observed in the cells treated with TGF-beta. The observation may suggest that TGF-beta may have effects upon cytoskeletal elements in osseous tissues.

Substitution at codon 269 (glutamine --> proline) of the leptin receptor (OB-R) cDNA is the only mutation found in the Zucker fatty (fa/fa) rat

We recently cloned one of spliced variant forms of rat leptin receptor (OB-R), which contains a short intracellular domain, and found obese-phenotype-linked nucleotide alteration in the extracellular domain of the cDNA from the Zucker (fa/fa) rat, which results in a glutamine269 to proline269 amino acid substitution. Reported herein are the cloning and sequencing of another spliced variant forms of rat OB-R cDNA with a long intracellular domain. Both forms of OB-R cDNA share the same extracellular domain. In the Zucker (fa/fa) rat, no changes in either the gene structure nor in the nucleotide sequence of the long intracellular domain were observed. However, the expression level of OB-R mRNA in the brain of Zucker (fa/fa) rat was higher than for lean littermates. These facts suggest that the substitution at codon 269 of the OB-R cDNA represents the crucial mutation which results in the obese phenotype of Zucker (fa/fa) rat.

Case report: hippocratic digital and Crohn's disease

A case of Hippocratic digital associated with secondary hypertrophic osteoarthropathy complicating Crohn's disease in a 29 year old Japanese male is reported. Hippocratic digital, or finger clubbing, complicating inflammatory bowel disease has been frequently reported in the Western hemisphere. However, its association with secondary hypertrophic osteoarthropathy has been very rarely found in that disease. In Japan, Hippocratic digital has not been described previously. With regard to the pathogenesis of Hippocratic digital and secondary hypertrophic osteoarthropathy, the theory that both entities belong to the same pathological spectrum and that megakaryocytes or platelet clumps may play the most important role, is discussed.

[Diagnosis of superficial-type early carcinoma of the gallbladder by endoscopic ultrasonography--comparison with ultrasonography]

The detectability of superficial-type carcinoma of the gallbladder by ultrasonography (US) and endoscopic ultrasonography (EUS) were investigated. Eight patients with such carcinoma of the gallbladder were reviewed. They had undergone both US and EUS previous to surgery. The tumor was detected in 3 patients by US, 2 patients with IIa + IIb-type carcinoma and 1 patient with IIa-type carcinoma. Those lesions were visualized as localized thickening of the gallbladder wall or as broad-based tumor. In 2 patients, lesions were not initially detected by US, but were shown by US after the examination by EUS. The tumor was detected by EUS also in 1 case of IIb + IIa-type carcinoma besides those 3 patients mentioned above. All four of these lesions were visualized as broad-based tumor by EUS. It was difficult to detect pure IIb-type or small IIa-type carcinoma even by EUS. In patients with concomitant acute cholecystitis or gallbladder stone, it was difficult to evaluate the abnormal findings of the gallbladder wall.

Comparison of horizontal nystagmus in different head positions: a study by damped pendular rotation test

Damped pendular rotation was given with the initial maximum speed of 180 degrees/s. The subject's head was tilted forward at an angle of 30 degrees from the upright position, or kept in the upright position, or tilted backward at 30 degrees from the upright position. Electronystagmography was used to evaluate the maximal slow-phase eye velocity (mx SPEV) of the horizontal nystagmus. Differences existed in mx SPEVs of the horizontal nystagmus for the head-tilted positions at 30 degrees forward or backward and that obtained in the upright position. The mx SPEV of the horizontal nystagmus in the upright position was higher than those acquired in the head-tilted positions.

Drug sensitivity testing for clinical samples from oesophageal cancer using adhesive tumour cell culture system

A total of 83 specimens of surgically resected tumours from 78 patients with oesophageal cancer were assayed for drug sensitivity using an adhesive tumour cell culture system (LifeTrac CSA assay). Seventyone of 83 specimens had a sufficient number of cells to permit growth in culture and 57 of 71 (80%) were evaluable for drug response. Cells (3 x 10(3) ml-1 well-1) were cultured for 14 days and exposed to drugs on days 3-8. Growing cells were confirmed as cancer cells by immunohistochemical staining. IC90 values against several anti-cancer drugs were determined and population distributions of IC90 for each drug served as the basis for judging sensitivity. The 10th percentiles of IC90 (microgram ml-1) for CDDP, 5-FU, DOX, CPM, MTX, VP16, IFOS, VDS, BLM and CDDP + 5-FU were 0.3, 0.16, 0.005, 0.9, 0.006, 0.09, 0.8, 0.006, 0.04 and 0.15 + 0.09 respectively. The population distribution of IC90 against each drug showed a specific pattern that was very similar among histopathological gradings and stages of the disease. This system appeared to be a clinically applicable drug sensitivity test for human oesophageal cancer.

Incoherent pattern detection using a liquid-crystal active lens

Incoherent pattern detection by a simple imaging system using a liquid-crystal active lens is proposed. The imaging system works as a spatial filtering system with a rewritable phase-only filter. We found that, in the incoherent matched filtering system, a conventional phase-only filter has a higher optical efficiency but a lower pattern discrimination than a complex filter. To improve the pattern discrimination ability, we optimized the phase-only filter by using simulated annealing and a genetic algorithm. We designed phase-only filters that have discrimination ability comparable with that in a complex filter. The performance of optimized phase-only filters is experimentally demonstrated.

Contrasting effects of SM-9018, a potential atypical antipsychotic, and haloperidol on c-fos mRNA expression in the rat striatum

SM-9018 (cis-2-(4-(4-(1,2-benzisothiazol-3-yl)-1-piperazinyl)butyl) hexahydro-1 H-isoindole-1,3(2H)-dione HCl) is a potential atypical antipsychotic with high affinity for 5-HT2, dopamine D2 and 5-HT1A receptors. Northern blot analysis was performed to compare the effects of SM-9018 and of haloperidol on the striatal c-fos mRNA expression in rats. Haloperidol (0.3-30 mg/kg, p.o.) markedly increased the striatal c-fos mRNA levels (about eight-fold at 30 mg/kg), the increase being abolished by lesioning of dopamine neurons with 6-hydroxydopamine. In contrast, SM-9018 produced only a slight increase (about two-fold) in c-fos mRNA expression at doses up to 30 mg/kg (p.o.). The 5-HT2 receptor antagonist, ritanserin (0.1-3 mg/kg, i.p.), dose-dependently attenuated the haloperiodol-induced c-fos expression, but the putative 5-HT1A receptor antagonist, NAN-190 (1-(2-methoxyphenyl)-4-(4-(2-phethalimmido)butyl)piperazine HBr; 1-10 mg/kg, i.p.), did not. These findings suggest that SM-9018 is weaker than haloperidol for induction of striatal c-fos mRNA expression, to which the 5-HT2 receptor blocking activity of SM-9018 seems to contribute.

Phenotype-linked amino acid alteration in leptin receptor cDNA from Zucker fatty (fa/fa) rat

The mouse obese (ob) gene product (leptin), expressed specifically in adipose cells, regulates energy balance in mice. Both mouse diabetes (db) and rat fatty (fa) gene products are thought to play major roles in leptin signaling pathways in the hypothalamic area. Mutations of these genes in murines result in marked obesity and type II diabetes as part of a syndrome that resembles morbid obesity in humans. Reported herein are the cloning and sequencing of one of spliced variant forms of rat leptin receptor (OB-R) cDNA with a short intracellular domain. In the Zucker (fa/fa) rat, no changes in either the gene structure or the expression levels were observed. However phenotype-linked nucleotide alteration exists in the cDNA from Zucker (fa/fa) rat, which results in an amino acid substitution.

Loss of heterozygosity at the DCC gene locus is not crucial for the acquisition of metastatic potential in oesophageal squamous cell carcinoma

Tumour specimens from 111 patients with oesophageal squamous cell carcinoma were screened for loss of heterozygosity (LOH) at the deleted colorectal carcinoma (DCC) gene locus. DCC-LOH occurred in 10 of 61 informative cases (16%). No statistically significant correlation was observed between DCC-LOH and lymph node metastasis, histopathological grade or tumour stage. The survival of patients exhibiting DCC-LOH was not statistically different from that of patients without LOH. These results suggest that LOH at the DCC locus is not related to the acquisition of metastatic potential or the state of tumour cell differentiation in oesophageal squamous cell carcinoma.

Allograft stapes surgery for conductive hearing loss in patients with ossicular chain anomalies

An allograft stapes was used during surgical intervention for conductive hearing loss due to ossicular malformations in 11 ears of seven patients. The external auditory canal and tympanic membrane were normal in all ears. The surgical findings for the ossicles were stapes fixation (7 ears), stapes fixation with discontinuity of the incudostapedial joint (in both ears of one patient), a deformed incus and stapes crura compressed by the facial nerve (one ear in which the stapes was not fixed) and an anomaly of the incus and stapes combined with a dermoid cyst (in one ear in which the stapes was also not fixed). In all ears, the following procedures were performed: stapedectomy followed by sealing the oval window with a vein graft and placing an allograft stapes between the oval window and the lenticular process of the incus or the handle of the malleus. The allograft stapes was placed with its capitulum on the oval window in all cases, and fibrin glue was used for stabilizing the seal and the allograft stapes. The indications for stapedectomy for conductive hearing loss due to ossicular chain anomalies and the utility of allograft stapes are discussed.

Quantification of genistein and genistin in soybeans and soybean products

It has been suggested that the isoflavone, genistein,, may have some role as a chemopreventive agent against cancer in humans. Levels of genistein and its beta-glucoside conjugate, genistin, ingested in soybeans and related bean products by the Japanese were quantified by HPLC, to estimate daily intake of these compounds. Amounts of genistein and genistin in soybeans, soy nuts and soy powder were in the range of 4.6 to 18.2 and 200.6 to 968.1 micrograms/g food, respectively. The values for soy milk and tofu (bean curd) were 1.9 to 13.9 and 94.8 to 137.7 micrograms/g food, respectively. Levels of isoflavones in fermented soybean products, miso (bean paste) and natto (fermented soybeans), were 38.5 to 229.1 micrograms/g food for genistein and 71.7 to 492.8 micrograms/g food for genistin. Thus, the level of genistein in the fermented soybean products was higher than in soy beans and soybean products such as soy milk and tofu. From these observations, it is suggested that the beta-glycosyl bond of genistin is cleaved to produce genistein by microbes during fermentation to yield miso and natto. Soy sauce was also found to contain both isoflavones, but at levels lower than in miso and natto. On the basis of these data for average annual consumption of soybeans and related products, daily intake of genistein and genistin by the Japanese is calculated to be 1.5-4.1 and 6.3-8.3 mg/person, respectively. These levels are much higher than those for Americans or Western Europeans, whose mortality rates for breast, colon and prostate cancers are greater than the Japanese.

Exercise training has a long-lasting effect on prevention of non-insulin-dependent diabetes mellitus in Otsuka-Long-Evans-Tokushima Fatty rats

Exercise training has been shown to be effective in preventing the development of non-insulin-dependent diabetes mellitus (NIDDM) in a model rat (Otsuka-Long-Evans-Tokushima Fatty [OLETF]). For determination of how long a preventive effect of exercise training against the development of NIDDM lasts in this model, six male OLETF rats each were assigned to training (1) for a whole experimental period, from 7 to 28 weeks of age (E-E); (2) for the first half of the period, from 7 to 15 weeks of age (E-S); and (3) for the second half of the period, from 16 to 28 weeks of age (S-E). In addition, eight male OLETF rats were given no exercise during the experimental period (S-S). At 28 weeks of age, E-E, E-S, S-E, and S-S rats, weighed averages of 514, 542, 557, and 669 g and had abdominal fat deposits of 13.9, 21.3, 38.2, and 76.0 g, respectively. At 28 weeks of age, the cumulative incidence of NIDDM in S-S was 100%, while none of the trained rats were diabetic. The glucose infusion rate (GIR) during a hyperinsulinemic euglycemic clamp test, an index of insulin sensitivity, in the E-E group was significantly greater than that in the S-S group. The values in the E-S and S-E groups were slightly, but not significantly, less than that in the E-E group. Morphologic studies on the pancreas of E-E rats and S-E rats showed minimal changes of islets, whereas sections of islets from E-S rats appeared slightly enlarged and fibrotic, although significantly less than those of islets of S-S rats. These results demonstrate that the preventive effect of excercise training against the development of NIDDM lasts for at least 3 months after the cessation of exercise in this model.

Effects of transfection with the Cu, Zn-superoxide dismutase gene on xanthine/xanthine oxidase-induced cytotoxicity in fibroblasts from rat skin

PURPOSE

The effects of transfection with the human Cu, Zn-superoxide dismutase (hSOD)4 gene on active oxygen-induced cytotoxicity in rat skin fibroblasts (FR) were studied for the purpose of developing the novel delivery system of hSOD using hSOD gene.

METHODS

An expression plasmid for hSOD, pRc/RSV-SOD, was constructed and used to transfect FR cells. Xanthine (X)/xanthine oxidase (XO) system were used to generate active oxygen species. The effects of transfection with the hSOD gene on active oxygen-induced cytotoxicity were assessed by comparing the number of surviving cells and the level of lipid peroxidation in host and transformants after exposure to X/XO system.

RESULTS

The cellular SOD activity in RSV-SOD cells transfected with pRc/RSV-SOD was significantly increased in comparison with host or RSV cells transfected with the pRc/RSV plasmid containing no hSOD gene as a control. Furthermore, Western blot analysis using an anti-hSOD antibody indicated the production of hSOD in RSV-SOD cells. On the other hand, although the numbers of surviving cells in both host and RSV-SOD cultures after exposure to X/XO system decreased in a time-dependent manner, the decrease in number of surviving RSV-SOD cells was less than that in host cells. In the presence of catalase, the decreases in number of surviving cells in both host and RSV-SOD cultures after exposure to the X/XO system were also less than those in the absence of catalase. However, the decreases in cell survival in RSV-SOD cultures were significantly less than those in host cells in the presence of catalase. Furthermore, the levels of lipid peroxidation in RSV-SOD cells exposed to the X/XO system in the presence or absence of catalase were lower than those in host cells. These results indicated that the increase in cellular SOD activity by transfection with the hSOD gene protects cells from oxidative stress.

CONCLUSIONS

Human SOD gene therapy may be useful for treatment of diseases in which oxidative tissue damage is produced.

Suppression of azoxymethane-induced aberrant crypt foci in rat colon by nimesulide, a selective inhibitor of cyclooxygenase 2

Non-steroidal anti-inflammatory drugs, such as piroxicam and sulindac, are known to inhibit development of aberrant crypt foci (ACF) and cancer in the colon. However, these agents cause gastrointestinal side-effects. Nimesulide is a selective inhibitor of cyclooxygenase 2 and has been shown to have a more potent anti-inflammatory action than piroxicam, but be less ulcerogenic and, therefore, a potentially more useful chemopreventive agent. To assess this possibility the inhibitory effects of nimesulide on the formation of ACF induced by azoxymethane in rat colon were investigated, and compared with those of piroxicam and sulindac. Male F344 rats were treated s.c. with 15 mg/kg body weight azoxymethane once a week for 2 weeks and given 50, 100 or 200 ppm nimesulide, 200 ppm piroxicam, or 200 ppm sulindac in their diet from the day before the first carcinogen treatment until the end of the experiment at week 4. At this time, nimesulide at doses of 50, 100 and 200 ppm had reduced the numbers of azoxymethane-induced ACF to 75%, 71% and 65% respectively compared to the control. The number of azoxymethane-induced ACF per colon in the group given 200 ppm nimesulide was almost the same as in those given 200 piroxicam, and lower than that in the group given 200 ppm sulindac. These results suggest that nimesulide, a selective cyclooxygenase 2 inhibitor, warrants attention as a candidate for chemopreventive agent with low toxicity, active against colon carcinogenesis.