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Gene modulation by the cyclooxygenase inhibitor, sulindac sulfide, in human colorectal carcinoma cells: possible link to apoptosis.

The mechanisms underlying the anti-tumorigenic properties of cyclooxygenase inhibitors are not well understood. One novel hypothesis is alterations in gene expression. To test this hypothesis sulindac sulfide, which is used to treat familial adenomatous polyposis, was selected to detect gene modulation in human colorectal cells at physiological concentrations with microarray analysis. At micromolar concentrations, sulindac sulfide stimulated apoptosis and inhibited the growth of colorectal cancer cells on soft agar. Sulindac sulfide (10 microm) altered the expression of 65 genes in SW-480 colorectal cancer cells, which express cyclooxygenase-1 but little cyclooxygenase-2. A more detailed study of 11 genes revealed that their expression was altered in a time- and dose-dependent manner as measured by real-time RT-PCR. Northern analysis confirmed the expression of 9 of these genes, and Western analysis supported the conclusion that sulindac sulfide altered the expression of these proteins. Cyclooxygenase-deficient HCT-116 cells were more responsive to sulindac sulfide-induced gene expression than SW-480 cells. However, this response was diminished in HCT-116 cells overexpressing cyclooxygenase-1 compared with normal HCT-116 cells suggesting the presence of cyclooxygenase attenuates this response. However, prostaglandin E2, the main product of cyclooxygenase, only suppressed the sulindac sulfide-induced expression of two genes, with little known biological function while it modulated the expression of two more. The most likely explanation for this finding is the metabolism of sulindac sulfide to inactive metabolites by the peroxidase activity of cyclooxygenase. In conclusion, this is the first report showing sulindac sulfide, independent of cyclooxygenase, altered the expression of several genes possibly linked to its anti-tumorigenic and pro-apoptotic activity.

Anti-Inflammatory Agents, Non-Steroidal↗

Anti-angiogenic and apoptotic effects of metabolites of sulindac on chick embryo chorioallantoic membrane.

Sulindac and other nonsteroidal anti-inflammatory drugs (NSAIDs), in addition to anti-inflammatory properties, express preventive activity against colon cancer. This antineoplastic effect may result from the suppression of polyp development in patients with familial adenomatous polyposis. However, despite intense investigations the exact mechanism for sulindac protective effect is not fully elucidated. Angiogenesis, the process of new blood vessel formation, is required to support tumor growth and may be partially involved in the transformation of polyps into tumor. Therefore, we tested the hypothesis whether sulindac might inhibit angiogenesis. The effects of sulindac metabolites, sulindac sulfide and sulindac sulfone, on vascular development were evaluated using the chick embryo chorioallantoic membrane (CAM) assay in vivo. The angiogenic response was quantitated by several methods including direct stereomicroscopic observation, measurements of hemoglobin content and DNA synthesis whereas quantitation of apoptosis was based on determinations of caspase-3 activity, caspase-3 and bax protein expression, and nuclear DNA fragmentation. Our results indicated that both sulindac metabolites were equally effective in inhibition of new blood vessel formation in CAM during chick embryo development. Moreover, both metabolites of sulindac induced the process of apoptosis parallelly to the inhibition of angiogenesis.

Allantois↗

Effects of sulindac and oltipraz on the tumorigenicity of 4-(methylnitrosamino)1-(3-pyridyl)-1-butanone in A/J mouse lung.

The efficacies of the non-steroidal, anti-inflammatory drug sulindac and the schistosomicidal agent oltipraz in inhibiting lung tumorigenesis was measured in A/J mice. Lung tumors (15.7 tumors/mouse) were induced by the tobacco-specific nitrosamine 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK; 9.1 mg/mouse) administered in drinking water for 7 weeks. Feeding mice with sulindac (123 mg/kg diet), 2 weeks before carcinogen treatment until they were killed reduced tumor multiplicity by 53%. Oltipraz (250 mg/kg diet), however, has no effect on tumorigenesis. The absorption and metabolism of NNK were compared in the stomachs and intestines isolated from mice fed AIN-76A diet or sulindac + diet. Sulindac had no effect on alpha-carbon hydroxylation, pyridine N-oxidation or carbonyl reduction of NNK. Mouse lung explants were cultured with 4.7 microM [5-3H]NNK for 4 or 8 h. The addition of 1 mM sulindac to the culture medium reduces the alpha-carbon hydroxylation and pyridine N-oxidation of NNK. However, the administration of sulindac in the diet prior to the excision of the lung explants had no effect on these two metabolic pathways. We compared the levels of sulindac and its sulfide and sulfone metabolites in the lungs, livers and plasma of mice fed an AIN-76A diet containing 130 mg sulindac/kg for 2 weeks. The sulfide metabolite was the most abundant of the three compounds in plasma (17.6 pmol/microliters) and liver tissues (17.7 pmol/mg) but it could not be detected in lung tissues. These results show that non-steroidal anti-inflammatory drugs constitute a new class of chemopreventive agents in lung tumorigenesis. The tumor chemopreventive activity of sulindac is not mediated by the sulfide metabolite responsible for its anti-inflammatory activity.

Adenoma↗

Suppression of tumorigenesis in the Apc(min) mouse: down-regulation of beta-catenin signaling by a combination of tea plus sulindac.

Epidemiological and animal studies suggest that tea may be protective towards cancers of the GI tract. White tea, the least processed form of tea, contains high levels of polyphenols and, like green tea, is chemopreventive towards heterocyclic amine-initiated colonic aberrant crypt formation in male F344 rats. We examined for the first time the relative effectiveness of white and green tea in suppressing intestinal tumorigenesis in C57BL/6J-Apc(Min/+) (Apc(min)) mice. Each tea was also compared with sulindac, a non-steroidal anti-inflammatory drug known to be highly effective in Apc(min) mice. Male C57BL/6J (+/+) (wild-type) and Apc(min) mice were treated in the drinking water with white tea or green tea (1.5% w/v, 2 min brew-time), 80 p.p.m. sulindac, a combination of 80 p.p.m. sulindac in 1.5% white tea, or pH buffered water. After 12 weeks of treatment, Apc(min) mice given white tea, green tea, or sulindac had significantly fewer tumors than controls (P < 0.05). The protection provided by 1.5% green or white tea was comparable to that provided by 80 p.p.m. sulindac. Mice treated with a combination of white tea plus sulindac had significantly fewer tumors than either treatment alone (P < 0.05). beta-catenin and beta-catenin/Tcf-4 regulated proteins Cyclin D(1) and c-Jun were readily detected in polyps, but markedly reduced in normal-looking intestines of mice treated with both tea and sulindac. This research provides evidence that teas, particularly when administered in combination with sulindac, are highly effective at inhibiting intestinal neoplasia in male Apc(min) mice via direct or indirect effects on the beta-catenin/APC pathway.

Animals↗

Inhibition of colon cancer precursors in the rat by sulindac sulphone is not dependent on inhibition of prostaglandin synthesis.

The non-steroidal anti-inflammatory drug, sulindac, inhibits the growth of colorectal tumours in animal models of colon cancer and causes regression of polyps in patients with familial adenomatous polyposis. The mechanism by which sulindac exerts this inhibitory effect is not known, but it has been postulated to be via the inhibition of prostaglandin synthesis. However, two recent studies have indicated that sulindac sulphone, the non-prostaglandin inhibiting metabolite of sulindac, may be important in tumour inhibition. In the present study, we examined the effect of sulindac sulphone on the formation of aberrant crypt foci, the earliest identifiable lesions in the development of colorectal cancer, in the rat colon. We have previously shown that sulindac causes a dose dependent inhibition of aberrant crypt formation in this model. Aberrant crypt foci were induced with two oral doses of 1,2-dimethyl hydrazine at 25 mg/kg per dose. Treatment with sulindac sulphone at either 10 mg/kg b.d., or 20 mg/kg, b.d., was started on the day following administration of the first carcinogen dose and was continued for 3 weeks. Colons were then removed and examined for aberrant crypt foci. Colonic crypts were visualized by staining the unsectioned colon in 0.2% methylene blue solution. There was a significant reduction in the number of aberrant foci in rats treated with sulindac sulphone at 20 mg/kg, b.d. (ANOVA, P = 0.0054). The mechanism by which non-steroidal anti-inflammatory drugs inhibit formation of aberrant crypt foci is not clear; however, these data suggest that it is not due to the inhibition of prostaglandin synthesis.

Animals↗

Genetic polymorphisms of flavin monooxygenase 3 in sulindac-induced regression of colorectal adenomas in familial adenomatous polyposis.

Sulindac is a nonsteroidal antiinflammatory drug with a chemopreventive effect in patients with familial adenomatous polyposis (FAP). In vivo, the active form of sulindac is sulindac sulfide, which is inactivated by the hepatic microsomal enzyme, flavin monooxygenase 3 (FMO3). In humans, numerous polymorphisms exist in FMO3, which alter enzymatic activity and subsequent substrate metabolism. We recently showed that certain polymorphic forms of FMO3 with reduced activity were associated with a more favorable response to sulindac in preventing the formation of adenomas in patients with FAP without polyps at baseline. Here, we determined whether these FMO3 polymorphisms correlated with the ability of sulindac to regress polyposis in patients with FAP who had polyps prior to treatment. Nineteen patients were treated with 150 mg sulindac twice a day for 6 months. The size and number of polyps in each patient was assessed at baseline (prior to the administration of sulindac), and at 3 and 6 months. Genotyping was done on seven established FMO3 polymorphisms with functional significance-M66I, E158K, P153L, V257M, E305X, E308G, and R492W. Statistical analyses were done with Wilcoxon rank sum test. Of the loci examined, only E158K and E308G showed polymorphic changes. Six patients exhibited polymorphisms in both E158K and E308G loci and were designated as genotype combination 1. The remaining patients were designated as genotype combination 2. Over the course of treatment, patients with genotype combination 1 had a greater reduction in both the size and number of polyps than those with genotype combination 2. These results suggest that combined polymorphic changes in the E158K and E308G alleles may protect against polyposis in patients with FAP treated with sulindac.

Adenoma↗

Sulindac sulfide and exisulind inhibit expression of the estrogen and progesterone receptors in human breast cancer cells.

In previous studies, we found that sulindac sulfide and exisulind (sulindac sulfone, Aptosyn) cause growth inhibition, arrest cells in the G1 phase of the cell cycle, and induce apoptosis in human breast cancer cell lines. These effects were associated with decreased expression of cyclin D1. The present study focuses on the effects of sulindac sulfide and exisulind on hormone signaling components in breast cancer cells. We found that estrogen receptor (ER)-positive and progesterone receptor (PR)-positive T47D breast cancer cells were somewhat more sensitive to growth inhibition by sulindac sulfide or exisulind than ER-negative PR-negative MB-MDA-468 breast cancer cells. Further studies indicated that sulindac sulfide and exisulind caused marked down-regulation of expression of the ER and PR-A and PR-B in T47D cells. However, neither compound caused a major change in expression of the retinoic acid receptor alpha (RARalpha), RARbeta, or RARalpha in T47D cells. Sulindac sulfide and exisulind also caused a decrease in expression of the ER in estrogen-responsive MCF-7 breast cancer cells. Both compounds also markedly inhibited estrogen-stimulated activation of an estrogen-responsive promoter in transient transfection reporter assays. Treatment of T47D cells with specific protein kinase G (PKG) activators did not cause a decrease in ER or PR expression. Therefore, although sulindac sulfide and exisulind can cause activation of PKG, the inhibitory effects of these two compounds on ER and PR expression does not seem to be mediated by PKG. Our findings suggest that the growth inhibition by sulindac sulfide and exisulind in ER-positive and PR-positive human breast cancer cells may be mediated, in part, by inhibition of ER and PR signaling. Thus, these and related compounds may provide a novel approach to the prevention and treatment of human breast cancers, especially those that are ER positive.

Breast Neoplasms↗

Sulindac sulfide-induced apoptosis is enhanced by a small-molecule Bcl-2 inhibitor and by TRAIL in human colon cancer cells overexpressing Bcl-2.

Sulindac is a nonsteroidal anti-inflammatory drug (NSAID) that induces apoptosis in cultured colon cancer cells and in intestinal epithelia in association with its chemopreventive efficacy. Resistance to sulindac is well documented in patients with familial adenomatous polyposis; however, the molecular mechanisms underlying such resistance remain unknown. We determined the effect of ectopic Bcl-2 expression upon sulindac-induced apoptotic signaling in SW480 human colon cancer cells. Sulindac sulfide activated both the caspase-8-dependent and mitochondrial apoptotic pathways. Ectopic Bcl-2 attenuated cytochrome c release and apoptosis induction compared with SW480/neo cells. Coadministration of sulindac sulfide and the small-molecule Bcl-2 inhibitor HA14-1 increased apoptosis induction and enhanced caspase-8 and caspase-9 cleavage, Bax redistribution, and cytochrome c and second mitochondria-derived activator of caspase release. Given that sulindac sulfide activated caspase-8 and increased membrane death receptor (DR4 and DR5) protein levels, we evaluated its combination with the endogenous death receptor ligand tumor necrosis factor-related apoptosis-inducing ligand (TRAIL). Coadministration of sulindac sulfide and TRAIL cooperatively enhanced apoptotic signaling as effectively as did HA14-1. Together, these data indicate that HA14-1 or TRAIL can enhance sulindac sulfide-induced apoptosis and represent novel strategies for circumventing Bcl-2-mediated apoptosis resistance in human colon cancer cells.

Antineoplastic Combined Chemotherapy Protocols↗

Combination of tumor necrosis factor-alpha with sulindac in human carcinoma cells in vivo.

Transcription factor NF-kappaB plays a pivotal role in cancer cells in the resistance to apoptosis, since NF-kappaB is frequently activated in many primary carcinoma cells. Indeed, several NF-kappaB inhibitors are found to be promising anti-cancer agents. However, some anti-cancer agents activate NF-kappaB signals and may reduce their potential, including tumor necrosis factor (TNF)-alpha. Recently, the nonsteroidal anti-inflammatory drug (NSAID) sulindac and its metabolites have been shown to inhibit the NF-kappaB-mediated survival signals through inhibition of IKK-beta by their direct interaction. We thus investigate whether sulindac and its metabolite can augment TNF-alpha-mediated apoptosis in human carcinoma cells and be applicable for in vivo clinical usage. We here demonstrate that sulindac inhibited TNF-alpha-mediated NF-kappaB activation and greatly enhanced TNF-alpha-induced apoptosis in human gastric MKN45 and cervical HeLa carcinoma cell lines. The in vivo tumor growth of MKN45 cells was most strongly inhibited by a combination of TNF-alpha with sulindac compared with TNF-alpha or sulindac alone. Moreover, we demonstrate that sulindac sulfide further augmented TNF-alpha-mediated apoptosis. Our data strongly suggest that combination therapy of TNF-alpha with sulindac and its metabolites may sensitize cancer cells to TNF-alpha and augment its pro-apoptotic potential. Therefore, in combination with sulindac or its metabolites, TNF-alpha may become a potentially useful anti-cancer agent to suppress tumor.

Apoptosis↗

Sulindac sulfone inhibits K-ras-dependent cyclooxygenase-2 expression in human colon cancer cells.

Both the sulfide and sulfone metabolites of sulindac, a nonsteroidal anti-inflammatory drug, display anticarcinogenic effects in experimental models. Sulindac sulfide inhibits cyclooxygenase (COX) enzyme activities and has been reported to suppress ras-dependent signaling. However, the mechanisms by which sulindac sulfone suppresses cancer growth are not as defined. We studied the effects of these sulindac metabolites in human colon cancer-derived Caco-2 cells that have been transfected with an activated K-ras oncogene. Stable transfected clones expressed high levels of COX-2 mRNA and protein, compared with parental cells. K-ras-transfected cells formed tumors more quickly when injected into severe combined immunodeficiency disease mice than parental cells, and this tumorigenesis was suppressed by treatment with sulindac. Sulindac sulfone inhibited COX-2 protein expression, which resulted in a decrease in prostaglandin synthase E2 production. Sulindac sulfide had little effect on COX-2 in this model, but did suppress prostaglandin synthase E2 production, presumably by inhibiting COX enzyme activity. These data indicate that the sulfide and sulfone derivatives of sulindac exert COX-dependent effects by distinct mechanisms.

Animals↗

Inhibition of extracellular signal-regulated kinase 1/2 phosphorylation and induction of apoptosis by sulindac metabolites.

Regular use of nonsteroidal anti-inflammatory drugs (NSAIDs) such as aspirin and sulindac is associated with a decreased mortality from colorectal cancer. Sulindac causes regression of precancerous adenomatous polyps and inhibits the growth of cultured colon cell lines. Whereas induction of apoptotic cell death is thought to account for the growth inhibitory effect of sulindac, less is known about its biochemical mechanism(s) of action. Sulindac is metabolized in vivo to sulfide and sulfone derivatives. Both the sulfide and sulfone metabolites of sulindac as well as more potent cyclic GMP-dependent phosphodiesterase inhibitors were shown to cause inhibition of extracellular signal-regulated kinase (ERK)1/2 phosphorylation at doses (40-600 microM) and times (1-5 days) consistent with the induction of apoptosis by the drugs. Treatment of HCT116 human colon cancer cells with the specific mitogen-activated protein kinase kinase, U0126 (5-50 microM) resulted in a time- and dose-dependent inhibition of ERK1/2 phosphorylation, and induction of apoptosis. U0126 treatment (20 microM) increased basal apoptosis, and potentiated the apoptotic effect of sulindac sulfide and sulindac sulfone. These results suggest that the inhibition of ERK1/2 phosphorylation is responsible for at least part of the induction of programmed cell death by sulindac metabolites. Inhibition of ERK1/2 activity may, therefore, be a useful biochemical target for the development of chemopreventive and chemotherapeutic drugs for human colon cancer.

3',5'-Cyclic-GMP Phosphodiesterases↗

The nonsteroidal anti-inflammatory drug sulindac causes down-regulation of signal transducer and activator of transcription 3 in human oral squamous cell carcinoma cells.

The nonsteroidal anti-inflammatory drug sulindac exerts a significant antineoplastic effect on several types of human cancers including oral squamous cell carcinoma (SCCa). Because constitutive activation of signal transducer and activator of transcription 3 (Stat3) has been linked to carcinogenesis of various tumors including head and neck SCCa, we studied whether sulindac treatment affects the Stat3 signaling pathway in oral SCCa cells. Western blot experiments showed that short-term treatment of cells with sulindac resulted in a large reduction of phosphorylated Stat3, without significantly affecting Stat3 protein levels. In contrast, 3 days of sulindac treatment eliminated both phosphorylated and unphosphorylated Stat3 protein levels. Also, sulindac treatment exerted a significant time-dependent cell growth-inhibitory effect on oral SCCa cells under the same conditions shown to induce Stat3 down-modulation. The sulfone metabolite of sulindac, which lacks cyclooxygenase-inhibitory activity, did not affect either Stat3 expression or Stat3 phosphorylation. Antisense oligonucleotide treatment against peroxisome proliferator-activated receptor gamma did not attenuate the ability of sulindac to down-regulate Stat3. Our results suggest that down-modulation of Stat3 can be induced by sulindac treatment, thus possibly contributing to the antineoplastic effect of this drug.

Anti-Inflammatory Agents, Non-Steroidal↗

Multicentre double-blind study of the efficacy, safety and tolerance of pirazolac compared with sulindac in patients with rheumatoid arthritis.

Of the 160 patients (80 pirazolac/80 sulindac) who entered the study through 14 investigators, three-quarters completed a 12-weeks therapy and three-fifths completed the entire 24-weeks therapy. In the pirazolac group 15% of the patients and in the sulindac group 11% dropped out from the study due to adverse clinical experience. The drop-out rates due to unsatisfactory therapeutic response were respectively 15% and 16% in the pirazolac and the sulindac groups. Both treatment groups showed significant improvement from baseline for all parameters except for the erythrocyte sedimentation rate at weeks 4, 8, 12 and 16 for the sulindac group and weeks 4 and 8 for the pirazolac group. The two treatment groups were comparable as to effectiveness; however, the improvement rates in 36 out of 41 efficacy measurements based on the definition of clinically relevant changes in relation to baseline were estimated to be superior for the group under pirazolac therapy. The rate of improvement for the American Rheumatism Association functional class at the end of the study was 23% in the pirazolac group and 9% in the sulindac group (p less than 0.05). Of the patients in the pirazolac and sulindac groups, 45% and 44% respectively reported no adverse effects at all throughout the whole 24-weeks study. The rates of patients reporting at least one adverse reaction in a body system were not different between the two groups. An exception was the body as a whole where ten patients (12.5%) in the sulindac group and only two (2.5%) in the pirazolac group reported adverse reactions (p = 0.03). No differences occurred between the two treatment groups with regards to intensity, causality or the number of occurrences of adverse clinical experiences. One death in the sulindac treatment group was reported during the study. In both treatment groups, alterations in laboratory tests were minor or negligible or associated with abnormal pre-treatment values and, generally speaking, without any clinical relevance. There were some patients, who had increases from baseline in alkaline phosphate in both treatment groups. However, these were usually transient, occasionally complemented by a slight increase of serum glutamic oxaloacetic acid transaminase.

Adult↗

Effect of uremia and anephric state on the pharmacokinetics of sulindac and its metabolites in rats. I. An application of pharmacokinetic model for reversible metabolism.

Plasma levels of sulindac and its metabolites, sulfide and sulfone, were measured in normal, uremic, and anephric rats following concurrent administration of 11C-sulindac and 3H-sulfide (5 mg-eq/kg). A marked decrease in plasma concentration of sulfide was found in uremic rats, while sulindac concentration in these rats was unchanged. In contrast, anephric rats cleared sulindac more slowly than control rats, but had no effect on the sulfide. A pharmacokinetic model for reversible metabolism was used to characterize the kinetic parameters for sulindac----sulfide interconversion system. The intrinsic clearances of unbound drug were calculated for the interconversion and elimination processes. The results indicated that the reduction of sulindac to sulfide is impaired in uremic and anephric rats. The oxidation of sulfide to sulindac was increased in uremic rats, but decreased in anephric rats. Experimental uremia caused a decrease in plasma protein binding of sulindac and sulfide and an increase in the apparent volumes of distribution of the redox species. Anephric state has less effect on plasma protein binding and volume distribution.

Animals↗

Effect of dimethyl sulfoxide on sulindac disposition in rats.

Sulindac and dimethyl sulfoxide (DMSO) are both effective antiinflammatory agents in man. Since the sulfoxide moiety in these compounds is metabolized similarly, a biochemical interaction between the two drugs in vivo was thought to be possible. After iv injections of sulindac (5 mg/kg), plasma concentrations of sulindac, and its sulfide and sulfone metabolites, were measured in normal rats and in rats that had received, 30 min earlier, a single ip dose of DMSO (0.1, 0.5, or 1.0 ml). The half-life of sulindac (normally 94 min) was increased significantly by DMSO (0.1, 0.5, or 1.0 ml). The half-life of sulindac (normally 94 min) was increased significantly by DMSO (408 min after 1.0 ml of DMSO). Plasma sulfide metabolite levels were reduced in a dose-related manner by DMSO (93% reduction in peak concentration after 1.0 ml of DMSO). Sulfone metabolite concentration was also significantly diminished by the highest dose of DMSO. Similarly, DMSO was shown to decrease conversion of sulindac to sulfide and sulfone metabolites by rat liver enzymes in vitro. Sulfoxide reductase was more sensitive to DMSO inhibition than was sulfoxide oxidase both in vivo and in vitro. These data demonstrate that DMSO can significantly alter in vivo the formation of the pharmacologically active, sulfide metabolite of sulindac; therefore, concurrent use of DMSO and sulindac should be approached with caution.

Animals↗

Renal metabolism of sulindac: functional implications.

We examined the metabolism of the prodrug sulindac sulfoxide and the active moiety, sulindac sulfide, in the isolated perfused kidney of the rabbit. Whether the sulfoxide or the sulfide was infused did not affect notably the pattern of drug efflux. In either case, the inactive sulfoxide and sulfone were the only forms recovered from urinary or venous effluents except for the appearance of a small amount of sulfide in the venous effluent after infusion of the sulfide. In contrast, large amounts of the sulfide were recovered from renal tissue, in addition to the inactive forms, after either prodrug or sulfide administration. We also examined the effects of the prodrug and the sulfide on stimulated release of prostaglandins in response to angiotensin II in the rabbit kidney and to norepinephrine in the rat kidney. Infusion of either 1 microgram/ml of sulindac sulfide or 10 micrograms/ml of sulfoxide inhibited prostaglandin release from both rabbit and rat kidneys. Inclusion of 2% bovine serum albumin in the perfusing medium largely confined radiolabeled forms of sulindac to the vascular space and inhibited oxidative inactivation of sulindac sulfide. However, inhibition of prostaglandin release by sulindac sulfide was only slightly reduced by protein binding. We conclude that 1) the kidney rapidly interconverts sulfide and sulfoxide forms; 2) the forms of sulindac present in renal tissue contrast with the inactive forms recovered from urinary and venous effluents; 3) either prodrug or sulfide administration can result in renal cyclooxygenase inhibition; and 4) protein binding restricts sulindac sulfide primarily to the vascular compartment but does not prevent inhibition of prostaglandin synthesis.

Animals↗

[Sulindac in familial adenomatous polyposis coli--preliminary findings of a prospective study].

Several authors have reported regression of rectal polyps after administration of sulindac in patients with familial adenomatous polyposis (FAP) and subtotal colectomy. However, only a few reports have been published about the effect of sulindac in the intact colon of FAP-patients. 12 patients (FAP n = 10, Lynch-I-syndrome n = 1, juvenile polyposis n = 1/patient with intact colon n = 6, ileorectal anastomosis n = 4, right-sided hemicolectomy n = 2) have been treated with sulindac (3 x 100 mg/d orally) for 4 months. In all patients colonoscopy (if postcolectomy, rectoscopy) with videotape documentation was performed before and after sulindac therapy. Some polyps were excised for histology. In 11/12 patients a regression of the number and size of polyps occurred. In addition, in patients with intact colon no polyps were observed proximal to the sigmoid colon. In one patient sulindac had to be discontinued after 4 weeks' course because of abdominal pain. A control colonoscopy revealed only slight reduction in polyps. In 3/12 patients no polyps remained after sulindac. In a further 3/12 patients with initial tubulous adenomatous polyps, only microadenomas were observed after treatment. We therefore conclude that sulindac is effective in FAP-patients (and very probably in other hereditary polyposis syndromes) with intact colon as well as after (hemi-)colectomy in reducing the number and size of polyps. Long term studies are needed to clarify the optimal dosage, treatment time period, and long term potential for development of carcinoma under sulindac treatment.

Adenomatous Polyposis Coli↗

Modulation of apoptosis by sulindac, curcumin, phenylethyl-3-methylcaffeate, and 6-phenylhexyl isothiocyanate: apoptotic index as a biomarker in colon cancer chemoprevention and promotion.

Recent evidence supports the theory that tumor growth in vivo depends on evasion of normal homeostatic control mechanisms that operate through induction of cell death by apoptosis. This study tested the hypothesis that several potential chemopreventive agents share the ability to induce apoptosis and that inhibition of apoptosis is a mechanism of tumor promoters. The present study was designed to investigate whether the chemopreventive properties of sulindac, curcumin, and phenylethyl-3-methylcaffeate (PEMC) and the tumor-promoting activity of 6-phenylhexyl isothiocyanate (PHITC) that were observed in our previous studies are associated with the induction or inhibition of apoptosis in azoxymethane (AOM)-induced colon tumors in male F344 rats. At 5 weeks of age, groups of rats were fed control (modified AIN-76A) diet or diets containing 320 ppm of sulindac, 2000 ppm of curcumin, 750 ppm of PEMC, or 640 ppm of PHITC. At 7 weeks of age, all rats except those intended for vehicle (normal saline) treatment were given AOM (15 mg/kg body weight) once weekly for 2 weeks. To study the effect of sulindac administered during promotion/progression stage, the rats were fed the control diet initially and then fed the experimental diet containing 320 ppm of sulindac 14 weeks after the second AOM treatment. The rats were sacrificed 52 weeks after carcinogen treatment, and their colonic tumors were subjected to histopathological evaluation and the appearance of apoptosis. In the current study, chronic administration of sulindac, curcumin, and PEMC or sulindac given only during promotion/progression significantly increased the apoptotic index (percentage of apoptosis) as compared to administration of the control diet; the apoptotic indices in the control, sulindac, curcumin, and PEMC diets were 8.3, 17.6, 17.7, and 18.5%, respectively, and in sulindac administered during promotion/progression stage, the apoptotic index was 19.1%. However, dietary PHITC blocked the process of apoptosis during colon carcinogenesis. The apoptotic index in PHITC diet was 7.0%. Taken together, our data show that chemopreventive properties of agents are correlated with the degree of apoptosis. Therefore apoptosis seems to be a reliable biomarker for the evaluation of potential agents for cancer prevention.

Adenocarcinoma↗