Sulindac and indomethacin inhibit formation of aberrant crypt foci in the colons of dimethyl hydrazine treated rats

Lipid Formulations and Bioconjugation Strategies for Indomethacin Therapeutic Advances

Indomethacin (IND) is a drug which after successful clinical trials became available for general prescription in 1965 and from that time is one of the most widely used anti-inflammatory drug with the highest potencies in the in vitro and in vivo models. However, despite its high therapeutic efficacy in relieving the symptoms of certain arthritis and in treating gout or collagen diseases, administration of IND causes a number of adverse effects, such as gastrointestinal ulceration, frequent central nervous system disorders and renal toxicity. These obstacles significantly limit the practical applications of IND and make that 10-20% of patients discontinue its use. Therefore, during the last three decades many attempts have been made to design novel formulations of IND aimed to increase its therapeutic benefits minimizing its adverse effects. In this review we summarize pharmacological information about IND and analyze its new lipid formulations and lipid bioconjugates as well as discuss their efficacy and potential application.

Dietary putrescine reduces the intestinal anticarcinogenic activity of sulindac in a murine model of familial adenomatous polyposis

The nonsteroidal antiinflammatory drug sulindac displays chemopreventive activity in patients with familial adenomatous polyposis (FAP). Sulindac metabolites induce apoptosis in colon tumor cells, in part, by a polyamine-dependent mechanism that can be suppressed with exogenous putrescine. To determine the relevance of this mechanism in animals, we treated Apc(Min/+) mice, a model of human FAP, with sulindac alone or in combination with dietary putrescine. Sulindac increased steady-state RNA levels and enzymatic activity of the polyamine catabolic enzyme spermidine/spermine N(1)-acetyltransferase and intestinal levels of monoacetylspermidine, spermidine, and spermine in the small intestine of mice. Sulindac also decreased the activity of the biosynthetic enzyme ornithine decarboxylase but not adenosylmethionine decarboxylase (AMD). Dietary putrescine increased intestinal putrescine contents, whereas the combination of dietary putrescine and sulindac yielded the highest levels of intestinal putrescine and correlated with a statistically significant reduction in AMD enzyme activity. Dietary putrescine did not statistically significantly increase tumorigenesis, although it significantly increased the grade of adenoma dysplasia (P < 0.05). The effectiveness of sulindac to suppress intestinal carcinogenesis was partially abrogated by dietary putrescine. These data suggest that sulindac exerts at least some of its anticarcinogenic effects in mice via a polyamine-dependent mechanism. Because high concentrations of putrescine can be found in certain dietary components, it may be advantageous to restrict dietary putrescine consumption in patients undergoing treatment with sulindac.

Celecoxib treatment alters the gene expression profile of normal colonic mucosa

A clinical trial was recently conducted to evaluate the safety and efficacy of a selective inhibitor of cyclooxygenase-2 (celecoxib) in hereditary nonpolyposis colon cancer patients. In a randomized, placebo-controlled phase I/II multicenter trial, hereditary nonpolyposis colon cancer patients and gene carriers received either celecoxib at one of two doses or placebo. The goal was to evaluate the effects of these treatment arms on a number of endoscopic and tissue-based biomarker end points after 12 months of treatment. As part of this trial, we analyzed gene expression by cDNA array technology in normal descending (rectal) colonic mucosa of patients before and after treatment with celecoxib or placebo. We found that treatment of patients with celecoxib at recommended clinical doses (200 and 400 mg p.o. bid), in contrast to treatment with placebo, leads to changes in expression of >1,400 genes in the healthy colon, although in general, the magnitude of changes is <2-fold. Twenty-three of 25 pairs of colon biopsies taken before and after celecoxib treatment can be classified correctly by the pattern of gene expression in a leave-one-out cross-validation. Immune response, particularly T- and B-lymphocyte activation and early steps of inflammatory reaction, cell signaling and cell adhesion, response to stress, transforming growth factor-beta signaling, and regulation of apoptosis, are the main biological processes targeted by celecoxib as shown by overrepresentation analysis of the distribution of celecoxib-affected genes across Gene Ontology categories. Analysis of possible cumulative effects of celecoxib-induced changes in gene expression indicates that in healthy colon, celecoxib may suppress the immune response and early steps of inflammation, inhibit formation of focal contacts, and stimulate transforming growth factor-beta signaling.

Aberrant crypt foci and beta-catenin accumulated crypts; significance and roles for colorectal carcinogenesis

Preneoplastic or precancerous lesions in the large bowel have been characterized in terms of morphology and histochemical phenotype. However, the detailed histogenesis and relation of particular lesions to malignancies has not yet to be unequivocally clarified. Aberrant crypt foci (ACF), identified in whole-mount preparations of colonic mucosa in rodents and also recognized in human colon, are now frequently used as effective surrogate biomarkers for experimentally detection of chemopreventive agents against colorectal cancers, but the preneoplastic or precancerous nature of ACF in rodents and humans still remains inconclusive. Relatively recently, early appearing beta-catenin accumulated crypts (BCAC) have been described in en face preparations of colonic mucosa in rodents which differ from ACF in many features. BCAC are suggested to be premalignant rather than preneoplastic. The pathological significance of both lesions, including their advantages and disadvantages as surrogate end points for large bowel neoplasms, and roles in colorectal carcinogenesis are discussed here.

Activity of the non-steroidal anti-inflammatory drug indomethacin against colorectal cancer

A substantial body of evidence from rodent colon carcinogenesis models, in vitro experiments with human colorectal cancer cells and limited clinical observations in humans suggest that the non-steroidal anti-inflammatory drug indomethacin has anti-colorectal cancer activity. However, although many mechanisms of the anti-neoplastic activity of indomethacin have been suggested, e.g., cyclooxygenase inhibition and peroxisome proliferator-activated receptor gamma activation, the precise relevance of the majority of in vitro pharmacological observations to the in vivo anti-neoplastic activity of indomethacin remains unclear. Herein, we review the existing literature describing the chemopreventative and chemotherapeutic efficacy of indomethacin against colorectal cancer, and draw together the disparate literature describing potential mechanisms of action of indomethacin in human colorectal cancer cells in vitro. Although indomethacin itself has significant adverse effects, including serious upper gastrointestinal toxicity, the development of novel derivatives that may have an improved safety profile means that further investigation of the anti-colorectal cancer activity of indomethacin is warranted.

Most effective colon cancer chemopreventive agents in rats: a systematic review of aberrant crypt foci and tumor data, ranked by potency

Potential chemopreventive agents for colorectal cancer are assessed in rodents. We speculated that the magnitude of the effect is meaningful and ranked all published agents according to their potency. Data were gathered systematically from 137 articles with the aberrant crypt foci (ACF) end point and from 146 articles with the tumor end point. The potency of each agent to reduce the number of ACF is listed in one table and the potency of each agent to reduce the tumor incidence in another table. Both tables are shown in this review and on a website with sorting abilities (http://www.inra.fr/reseau-nacre/sci-memb/corpet/indexan.html). Potency was estimated as the ratio of the value in control rats to the value in treated rats. From each article, only the most potent agent was kept, except in articles reporting the effect of more than seven agents. Among the 186 agents in the ACF table, the median agent reduced the number of ACF by one-half. The most potent agents to reduce azoxymethane-induced ACF were Pluronic, polyethylene glycol, perilla oil with beta-carotene, and sulindac sulfide. Among the 160 agents in the tumor table, the median agent reduced the tumor incidence in rats by one-half. The most potent agents to reduce the incidence of azoxymethane-induced tumors were celecoxib, a protease inhibitor from soy, difluoromethylornithine with piroxicam, polyethylene glycol, and a thiosulfonate. For the 57 agents present in both tables, a significant correlation (r) was found between the potencies against ACF and tumors (r = 0.45, P < 0.001); without celecoxib, a major outlying point in the correlation, r = 0.68 (P < 0.001, n = 56). In conclusion, this review gathers most known chemopreventive agents, ranks the most promising agents against colon carcinogenesis in rats or mice, and further supports the use of ACF as a surrogate end point for tumors in rats.

Short term infusion of glycine-extended gastrin(17) stimulates both proliferation and formation of aberrant crypt foci in rat colonic mucosa

Evidence is accumulating that gastrin precursors may act as growth factors for the colonic mucosa in vivo and for colorectal carcinoma cell lines in vitro. The effect of short term administration of synthetic gastrins on the colonic mucosa in vivo, however, has not been reported. The aim of our study was to determine whether continuous systemic infusion of glycine-extended gastrin(17) stimulated proliferation and accelerated carcinogenesis in the colorectal mucosa. A significant increase in colonic mucosal proliferation as assessed by metaphase index was seen in the caecum (23%, p < 0.02) and distal colon (27%, p < 0.001), but not the rectum, after treatment of intact rats with glycine-extended gastrin(17) for 1 week using implanted miniosmotic pumps. Defunctioning of the rectum reduced both the proliferative index and crypt height of the rectal mucosa of untreated rats. Treatment of rectally defunctioned animals with glycine-extended gastrin(17) for either 1 or 4 weeks resulted in a significant increase in both the proliferative index (40% and 93%, respectively) and crypt height (11% and 19%, respectively) of the rectal mucosa. The total number of aberrant crypt foci in intact rats treated with the procarcinogen azoxymethane plus glycine-extended gastrin(17) was increased by 48% compared to the value in controls treated with azoxymethane only (p = 0.01). We conclude that short term administration of glycine-extended gastrin(17) to mature rats not only has a proliferative effect upon colonic mucosa, but also increases the number of aberrant crypt foci formed in the colorectal mucosa after treatment with azoxymethane. Glycine-extended gastrin(17) could thus potentially act as a promoter of carcinogenesis.

Non-steroidal anti-inflammatory drugs with activity against either cyclooxygenase 1 or cyclooxygenase 2 inhibit colorectal cancer in a DMH rodent model by inducing apoptosis and inhibiting cell proliferation

BACKGROUND

Standard non-steroidal anti-inflammatory drugs (NSAIDs) reduce the risk of colorectal cancer by 40-60% but the mechanism by which this occurs is uncertain. Selective cyclooxygenase 2 inhibitors are potentially ideal chemopreventive agents as they are less toxic than standard NSAIDs. No study has compared the efficacy of these drugs at clinically relevant doses in a tumour model.

AIMS

To assess the efficacy of a range of NSAIDs with varying activity against the two cyclooxygenase isoforms in a rodent colorectal carcinogen model at anti-inflammatory doses and to explore the effect of NSAIDs on the rate of tumour apoptosis and proliferation.

METHODS

Colorectal tumours were induced in six week old Sprague-Dawley rats with five weekly doses of 1,2 dimethylhydrazine. Test agents were: indomethacin 2 mg/kg/day, meloxicam 0.6 mg/kg/day, celecoxib 6 mg/kg/day, and sulindac sulphone 40 mg/kg/day. Sulindac was tested at its chemoprotective dose of 20 mg/kg/day. After 23 weeks the number and volume of tumours per animal were recorded. Histology was performed. Tumour apoptosis was quantified on haematoxylin-eosin sections. Tumour proliferation was quantified using an immunohistochemical stain for bromodexoyuridine incorporation.

RESULTS

Test agents effectively reduced the number and volume of tumours developing in the treatment period. In all groups there was an increase in the rate of tumour apoptosis and a reduced rate of proliferation.

CONCLUSIONS

These data suggest that the chemopreventive effect of NSAIDs is independent of their cyclooxygenase inhibitory profile. One potential mechanism for their action may be through induction of apoptosis and inhibition of proliferation.

Non-steroidal anti-inflammatory drugs with different cyclooxygenase inhibitory profiles that prevent aberrant crypt foci formation but vary in acute gastrotoxicity in a rat model

BACKGROUND

Standard non-steroidal anti-inflammatory drugs (NSAIDs) reduce the risk of colorectal cancer; however, their use as preventive agents is limited by their inherent toxicity. Drugs that selectively inhibit cyclooxygenase-2 (COX-2) may be useful in this setting as they are supposedly less toxic. No study has directly compared the ability of standard NSAIDs and selective COX-2 inhibitors to inhibit colorectal cancer at clinically relevant doses.

METHODS

Aberrant crypt foci (ACF) were induced in Sprague-Dawley rats by using 1,2-dimethylhydrazine (DMH). Test agents or vehicle were then administered for 3 weeks, twice daily through orogastric gavage. At the end of this period, the number and multiplicity of ACF were determined. The agents tested at equivalent anti-inflammatory doses were: sulindac and indomethacin (standard NSAIDs), meloxicam (selective COX-2 inhibitor), celecoxib (specific COX-2 inhibitor) and sulindac sulfone (no known COX activity). Acute gastrotoxicity of NSAID in rats was compared by using quantitative histology.

RESULTS

All test agents reduced the number of ACF. There was a 42% reduction with indomethacin, 46% with sulindac, 46% with meloxicam, 22% with celecoxib and 36% with sulindac sulfone. Only the COX-2 inhibitors caused no significant gastrotoxicity in rats.

CONCLUSIONS

Cyclooxygenase-2 inhibitors are potentially ideal chemopreventive agents as they inhibit ACF and are not gastrotoxic.

Inhibition of rat colon tumors by sulindac and sulindac sulfone is independent of K-ras (codon 12) mutation

Nonsteroidal anti-inflammatory drug (NSAID) use reduces the risk of colorectal cancer by 40-50%. Previous studies suggest that effective inhibition of colorectal cancer by NSAIDs may be dependent on the presence or absence of a K-ras mutation. This study was aimed at determining the relationship between inhibition of colorectal cancer by sulindac and sulindac sulfone and the presence of activating K-ras mutations in the 1,2-dimethylhydrazine dihydrochloride rat model. Sulindac (20 mg x kg(-1) x day(-1)), sulindac sulfone (40 mg x kg(-1) x day(-1)), or vehicle was administered orally to male Sprague-Dawley rats for a 4-wk period beginning 20 wk after tumor induction. Tumor number and volume were measured before treatment by laparotomy and colonoscopy and again after treatment. Sulindac and sulindac sulfone treatment significantly reduced the number and volume of colorectal tumors compared with control rats. For K-ras (codon 12) mutation detection, frozen tumor tissue was collected at the endpoint. We found K-ras codon 12 mutations in 11 of 21 (52%) control tumors. The proportion of tumors with K-ras mutations in the sulindac-treated group [5 of 8 (62%); odds ratio = 1.51 (95% confidence interval = 0.29, 8.33)] and the proportion of sulindac sulfone-treated tumors [9 of 14 (64%); odds ratio = 1.63 (95% confidence interval = 0.41, 6.66)] were not significantly different from controls. Tumor inhibition did not correlate with K-ras (codon 12) mutation status, which suggests that the mechanism of inhibition of rat colorectal cancer by sulindac and sulindac sulfone is independent of K-ras mutation.