Treatment of colonic and rectal adenomas with sulindac in familial adenomatous polyposis

BACKGROUND

Familial adenomatous polyposis is an autosomal dominant disorder characterized by the formation of hundreds of colorectal adenomas and eventual colorectal cancer. Administration of the nonsteroidal antiinflammatory drug sulindac has been followed by regression of polyps in patients with this disorder, but no controlled trial of this drug in patients who have not had surgery has been reported.

METHODS

We conducted a randomized, double-blind, placebo-controlled study of 22 patients with familial adenomatous polyposis, including 18 who had not undergone colectomy. The patients received sulindac at a dose of 150 mg orally twice a day for nine months or identical-appearing placebo tablets. The number and size of the polyps were evaluated every three months for one year.

RESULTS

A statistically significant decrease in the mean number of polyps and their mean diameter occurred in patients treated with sulindac, as compared with those given placebo. When treatment was stopped at nine months, the number of polyps had decreased to 44 percent of base-line values and the diameter of the polyps to 35 percent of base-line values (P = 0.014 and P < 0.001, respectively, for the comparison with the changes in the group given placebo). No patient had complete resolution of polyps. Three months after treatment with sulindac was stopped, both the number and the size of the polyps increased in sulindac-treated patients but remained significantly lower than the values at base line. No side effects from sulindac were noted.

CONCLUSIONS

Sulindac reduces the number and size of colorectal adenomas in patients with familial adenomatous polyposis, but its effect is incomplete, and it is unlikely to replace colectomy as primary therapy.

Sulindac causes regression of rectal polyps in familial adenomatous polyposis

In familial adenomatous polyposis, sulindac-induced polyp regression has been reported by several authors. In this study, the goal was to confirm these results by a randomized, placebo-controlled, double-blind crossover study in 10 patients with rectal polyps that had been previously treated by colectomy and ileorectal anastomosis. Patients received sulindac, 300 mg/day, or placebo during two 4-month periods separated by a 1-month wash-out phase. One patient was not compliant and was excluded. With sulindac, the authors observed a complete (6 patients) or almost complete (3 patients) regression of the polyps. With placebo, the authors observed an increase (5 patients), no change (2 patients), and a relative decrease (2 patients) in the number of polyps. The difference between sulindac and placebo was statistically significant (P less than 0.01). In biopsy specimens of polyps and normal rectal mucosa of 6 patients, the authors conducted an immunohistochemical study of the cellular proliferation index using the Ki 67 monoclonal antibody (Ki 67 index), at the beginning and at the end of each treatment period. They were not able to show a sulindac-induced modification of the Ki 67 index. The authors conclude that sulindac is effective in inducing the regression of rectal polyps in familial adenomatous polyposis.

Aberrant crypt foci of the colon as precursors of adenoma and cancer

BACKGROUND

Aberrant crypt foci of the colon are possible precursors of adenoma and cancer, but these lesions have been studied mainly in surgical specimens from patients who already had colon cancer.

METHODS

Using magnifying endoscopy, we studied the prevalence, number, size, and dysplastic features of aberrant crypt foci and their distribution according to age in 171 normal subjects, 131 patients with adenoma, and 48 patients with colorectal cancer. We also prospectively examined the prevalence of aberrant crypt foci in 11 subjects (4 normal subjects, 6 with adenoma, and 1 with cancer) before and after the administration of 100 mg of sulindac three times a day for 8 to 12 months and compared the results with those in 9 untreated subjects (4 normal subjects and 5 with adenoma). All 20 subjects had aberrant crypt foci at base line.

RESULTS

We identified 3155 aberrant crypt foci, 161 of which were dysplastic; the prevalence and number increased with age. There were significant (P<0.001) correlations between the number of aberrant crypt foci, the presence of dysplastic foci, the size of the foci, and the number of adenomas. After sulindac therapy, the number of foci decreased, disappearing in 7 of 11 subjects. In the untreated control group, the number of foci was unchanged in eight subjects and slightly increased in one (P<0.001 for the difference between the groups).

CONCLUSIONS

Aberrant crypt foci, particularly those that are large and have dysplastic features, may be precursors of adenoma and cancer.

Combinatorial chemoprevention of intestinal neoplasia

A combination of two drugs afforded remarkable protection from intestinal neoplasia in APC(Min/+) mice, a murine model of human familial adenomatous polyposis (FAP). One of the drugs was sulindac, a prototypical non-steroidal anti-inflammatory drug with established chemopreventative activity. The second drug was EKI-569, a newly developed, irreversible inhibitor of the epidermal growth factor receptor kinase. Although 100% of the untreated APC(Min/+) mice developed approximately 20 polyps, nearly half the mice treated with these two agents developed no polyps at all. These results suggest a powerful strategy for the chemoprevention of human colonic neoplasia.

Sulindac for polyposis of the colon

Four members of a Gardner's syndrome family had rectal and colon polyposis treated with nonsteroid anti-inflammatory drugs. Three of these patients had had subtotal colectomy and ileoproctostomy and the residual polyps arose in the rectal mucosa. The polyps almost completely disappeared when sulindac was administered. Indomethacin therapy over the course of a preceding year was ineffective in one of these patients. One patient (case 4) had diffuse polyposis in an intact colon. After sulindac therapy for a year, only three small mucosal polyps could be identified by air contrast barium enema and colonoscopic examination. These observations confirm those of Pollard and Luckert [1,2] on rats with chemically induced polyposis of the intestinal tract.

Placental angioarchitecture in monochorionic twin pregnancies: relationship to fetal growth, fetofetal transfusion syndrome, and pregnancy outcome

OBJECTIVE

We sought to correlate placental vasculature with fetal growth and outcome in monochorionic twins.

STUDY DESIGN

Eighty-two patients with consecutive monochorionic pregnancies underwent biweekly ultrasonography for determination of fetal growth and well-being. After delivery, blinded placental injection studies delineated vascular anastomoses and territory share. Degree of balance in arteriovenous anastomoses equaled the number of arteriovenous anastomoses in one direction minus the number in the other.

RESULTS

Pregnancies affected by fetofetal transfusion syndrome (n = 21) had numbers of arteriovenous and venovenous anastomoses that were similar to those in pregnancies without fetofetal transfusion syndrome but fewer arterioarterial anastomoses (P <.0001). Fetofetal transfusion syndrome occurred in 78% of pregnancies with >/=1 arteriovenous and no arterioarterial anastomoses. Birth weight discordancy correlated with placental territory discordancy (P <.0001) and the degree of balance in arteriovenous anastomoses (P =.004). The larger placental share twin had a greater growth velocity than its smaller placental share co-twin (P =.008) for all but one anastomotic pattern. Where arteriovenous anastomoses were aligned with the net venous outflow to the fetus with the smaller territory, co-twins had similar birth weights and growth velocities irrespective of placental share. Fetal survival was higher in pregnancies with an arterioarterial anastomosis (P =.01) but lower with a venovenous anastomosis (P =. 01). Survival of both fetuses was inversely associated with birth weight discordancy (P <.0001).

CONCLUSION

Although interrelationships among the various types of anastomoses are complex, our data suggest that the placental territory share and the pattern of arteriovenous anastomoses influence fetal growth, that arterioarterial anastomoses protect against fetofetal transfusion syndrome, and that venovenous anastomoses reduce perinatal survival.

Randomized controlled trial of the effect of sulindac on duodenal and rectal polyposis and cell proliferation in patients with familial adenomatous polyposis

Twenty-four patients with familial adenomatous polyposis who had previously undergone prophylactic colectomy and had advanced duodenal polyposis were entered into a randomized trial to assess the effect of the non-steroidal anti-inflammatory drug sulindac on duodenal and rectal polyps. Polyp size and number were assessed by videotaped duodenoscopy (and rectoscopy in 14 patients) at entry and after 6 months of treatment; the tapes were compared by two assessors who were unaware of the randomization and the shuffled chronological order of the recordings. Mucosal cell proliferation was measured by in vitro incorporation of 5-bromo-2'-deoxyuridine. Sulindac therapy was associated with a reduction in epithelial cell proliferation in the duodenum (median labelling index (LI) 15.8 versus 14.4 per cent, P = 0.003) and a trend towards duodenal polyp regression (P = 0.12). In the rectum, cell proliferation showed a marked reduction (median LI 8.5 versus 7.4 per cent, P = 0.018), and significant (P = 0.01) polyp regression was seen. Rectal polyposis was less severe than that in the duodenum and responded more dramatically. Sulindac is a possible treatment for patients in whom rectal polyps have failed to show significant regression after ileorectal anastomosis and who are unsuitable for pouch surgery; it may be useful in early duodenal polyposis or as an adjunct after duodenal clearance.

Colorectal cancer and nonsteroidal anti-inflammatory drugs

The authors have presented a concise review of the studies which evaluate the risk of colorectal cancer among NSAID users. Animals studies have clearly documented a protective effect of NSAIDs in preventing colon cancers in a carcinogen-induced (AOM) model. NSAIDs are protective in the animal model, even if given 14 weeks after administration of the carcinogen, indicating that they must be playing a role very early in the adenoma-to-carcinoma sequence of events. Several studies have indicated that treatment of FAP patients with NSAIDs causes a regression of adenomas that were already present prior to initiation of NSAID therapy. Many epidemiological studies have examined the relationship between aspirin use and colorectal cancer. Most of these studies have shown a marked decrease in the relative risk (40-50%) of colorectal cancer among continuous aspirin users. The appropriate dose and duration of aspirin treatment for optimal effects are still unknown. Future work, directed at the molecular basis for the chemoprotective effects of NSAIDs in humans, may reveal strategies for the development of better chemopreventive agents. One effect shared by all NSAIDs is their ability to inhibit cyclooxygenase. Presently, it is not clear whether inhibition of cyclooxygenase-1 or -2 effects on other signaling pathways are required for the protective effect of aspirin and other NSAIDs. The authors and others have demonstrated that COX-2 is upregulated from 2- to 50-fold in 85-90% of colorectal adenocarcinomas, which makes the COX-2 enzyme a possible target. Drugs are currently under development at several pharmaceutical companies that preferentially inhibit either COX-2 or COX-2. If COX-2 is found to be a relevant target in the prevention of colorectal cancer, then these newly developed, more selective NSAIDs may play a role in future chemoprevention strategies.

Effects of sulindac and ibuprofen in patients with chronic glomerular disease. Evidence for the dependence of renal function on prostacyclin

We investigated whether the glomerular synthesis of prostacyclin modulates the renal blood flow and glomerular filtration rate in chronic glomerular disease. The urinary excretion of 6-keto-prostaglandin F1 alpha, a stable breakdown product of prostacyclin, was significantly (P less than 0.01) reduced in 20 women with chronic glomerular disease, as compared with 19 controls, whereas excretion of urinary prostaglandin E2 was unchanged. In 10 patients randomly assigned to one week of treatment with ibuprofen, excretion of urinary 6-keto-prostaglandin F1 alpha and prostaglandin E2 was reduced by 80 per cent, the level of serum creatinine was increased by 40 per cent, and creatinine and para-aminohippurate clearances were reduced by 28 and 35 per cent, respectively. The reduction of both clearances was inversely related (P less than 0.01) to the basal urinary excretion of 6-keto-prostaglandin F1 alpha but not of prostaglandin E2. No functional changes were detected in five healthy women, despite a similar suppression of renal prostacyclin synthesis by ibuprofen. In contrast, one week of treatment with sulindac did not affect renal prostacyclin synthesis or renal function in the other 10 patients, despite a marked inhibition of extrarenal cyclooxygenase activity. We conclude that in patients with mild impairment of renal function, the renal blood flow and glomerular filtration rate are critically dependent on prostacyclin production. In such patients sulindac may be a safe substitute for other nonsteroidal antiinflammatory drugs.

Primary chemoprevention of familial adenomatous polyposis with sulindac

BACKGROUND

Familial adenomatous polyposis is caused by a germ-line mutation in the adenomatous polyposis coli gene and is characterized by the development of hundreds of colorectal adenomas and, eventually, colorectal cancer. Nonsteroidal antiinflammatory drugs can cause regression of adenomas, but whether they can prevent adenomas is unknown.

METHODS

We conducted a randomized, double-blind, placebo-controlled study of 41 young subjects (age range, 8 to 25 years) who were genotypically affected with familial adenomatous polyposis but phenotypically unaffected. The subjects received either 75 or 150 mg of sulindac orally twice a day or identical-appearing placebo tablets for 48 months. The number and size of new adenomas and side effects of therapy were evaluated every four months for four years, and the levels of five major prostaglandins were serially measured in biopsy specimens of normal-appearing colorectal mucosa.

RESULTS

After four years of treatment, the average rate of compliance exceeded 76 percent in the sulindac group, and mucosal prostaglandin levels were lower in this group than in the placebo group. During the course of the study, adenomas developed in 9 of 21 subjects (43 percent) in the sulindac group and 11 of 20 subjects in the placebo group (55 percent) (P=0.54). There were no significant differences in the mean number (P=0.69) or size (P=0.17) of polyps between the groups. Sulindac did not slow the development of adenomas, according to an evaluation involving linear longitudinal methods.

CONCLUSIONS

Standard doses of sulindac did not prevent the development of adenomas in subjects with familial adenomatous polyposis.

Sulindac for polyposis of the colon

The effect of sulindac, a nonsteroid antiinflammatory drug, on colon polyposis has been evaluated in seven patients after subtotal colectomy and ileoproctostomy and in four patients with intact colons. The patients all had Gardner's syndrome or familial polyposis coli. All polyps were eliminated, except for a few that arose in the rectal mucosa and the anal canal. No cancers developed in these patients on follow-up.

COX-2 inhibition and colorectal cancer

Mortality in patients with advanced colorectal cancer(CRC) remains high. Epidemiologic studies show that individuals taking nonselective, nonsteroidal anti-inflammatory drugs, including aspirin, have a significant reduction in CRC mortality, compared with those not taking these agents. The recent characterization of cyclooxygenase- I and -2 (COX- I and COX-2) isoforms has led to an expanded understanding of how nonsteroidal anti-inflammatory drugs may help prevent polyp formation. Cyclooxygenase enzymes are required for the conversion of arachidonic acid to prostaglandins.COX-2 mediates the inflammatory effects of COX activity, is induced by a wide spectrum of growth factors and proinflammatory cytokines, and is overexpressed in numerous premalignant and malignant lesions, including CRC. Treatment with the selective COX-2 inhibitor celecoxib has shown promising results in the prevention of CRC, Numerous studies show that this COX-2 selective inhibitor is a potent suppressor of colon polyps both in animal models for familial adenomatous polyposis and in patients with this condition. This has led to the US Food and Drug Administration approval of celecoxib for the treatment of patients with familial adenomatous polyposis. The role of celecoxib in cancer treatment is still evolving. Recent studies have identified a potential benefit for adding celecoxib to standard CRC chemotherapy regimens to increase their efficacy and reduce their associated toxicity.

The effects of sulindac on colorectal proliferation and apoptosis in familial adenomatous polyposis

BACKGROUND & AIMS

The mechanism by which sulindac causes regression of adenomas in patients with familial adenomatous polyposis (FAP) is unclear. Conflicting data on the drug's effects on colorectal epithelial proliferation have been reported. An alternative mechanism, and one not previously studied, is via induction of colorectal epithelial cell apoptosis (programmed cell death). This hypothesis was tested by studying the effects of sulindac on colorectal epithelial proliferation and apoptosis in patients with FAP.

METHODS

Cell proliferation was studied via immunohistochemistry for cell nuclear antigen in a group of 22 patients randomized to either sulindac (150 mg twice a day) or placebo in a previously published trial. The rectal epithelium from 7 additional patients with FAP treated with sulindac was examined by flow cytometry to assess changes in cell-cycle distribution and apoptosis.

RESULTS

Although sulindac caused a significant decrease in polyp size and number, there was no significant change in cytokinetic variables or cell cycle distribution 3 months after treatment. However, the subdiploid apoptotic fraction was increased significantly 3 months after treatment with sulindac (31.3% +/- 4.8% compared with 10% +/- 4.3% at baseline; P = 0.01).

CONCLUSIONS

Our findings suggest that sulindac does not affect colorectal epithelial proliferation and that its effects in patients with FAP may instead result from induction of apoptosis.

Nonsteroidal anti-inflammatory drugs, eicosanoids, and colorectal cancer prevention

A concise review of the literature that evaluates the risk of colorectal cancer among NSAID users has been presented. Animal studies document a protective effect of NSAIDs in preventing colorectal cancers in carcinogen-induced (AOM) models and in Min mice. NSAIDs are protective in the animal model, even if given 14 weeks after administration of the carcinogen, indicating that these agents must be acting early in the adenoma-to-carcinoma sequence. Treatment of FAP patients with NSAIDs causes regression of adenomas that were already present before initiation of therapy. Many epidemiologic studies have examined the relationship between aspirin use and colorectal cancer. Most show a marked decrease in the relative risk (40% to 50%) of this tumor among continuous aspirin users. The appropriate dose and duration of aspirin treatment needed for optimal results are still unknown. Future work, directed at the molecular basis for the chemoprotective effects of NSAIDs in humans, may reveal strategies for the development of better chemopreventive agents. One effect shared by all NSAIDs is inhibition of cyclooxygenase. Presently, whether inhibition of COX-1 or COX-2 is required for the protective effect of aspirin and other NSAIDs is unclear. The authors and others have demonstrated that COX-2 is up-regulated from 2 to 50 fold in 85% to 90% of colorectal adenocarcinomas, making the COX-2 enzyme a more likely target. The authors have also reported a dramatic increase in COX-2 expression in colon tumors that develop in rats after AOM treatment. Drugs are currently being developed that preferentially inhibit either COX-1 or COX-2. If COX-2 is found to be a relevant target in the prevention of colorectal cancer, these newly developed, selective NSAIDs may play a role in future chemoprevention strategies.

Mesenteric fibromatosis complicating familial adenomatous polyposis: predisposing factors and results of treatment

Between January 1975 and December 1983, 24 of 183 patients (13%) with familial adenomatous polyposis (FAP) seen at the Mayo Clinic had mesenteric fibromatosis (MF). MF was found most often in FAP patients with associated extra-colonic "Gardner" signs (19 patients) and those who had had previous abdominal surgery (20 patients). In 4 patients, MF appeared spontaneously. The male-to-female ratio was 0.4, with a median age of 31 years in women and 37 years in men. Ten of 24 patients (42%) had been asymptomatic prior to diagnosis at time of surgery for FAP. Complications of the disease included intestinal or urinary tract obstruction. Minimal surgical manipulation seemed to be associated with fewer postoperative complications and a lesser risk of regrowth of the tumor. Nonsurgical treatment, including tamoxifen and sulindac in combination, may be beneficial. Surgery should be reserved for relief of obstruction, and bypass is preferred to resection.

Testolactone, sulindac, warfarin, and vitamin K1 for unresectable desmoid tumors

Ten patients with large inoperable desmoid tumors in various body locations were treated with testolactone. Four tumors (40%) responded with major regressions, i.e., more than 50% reduction in volume. Eight patients received nonsteroid anti-inflammatory drugs (indomethacin, sulindac, or sulindac with warfarin and vitamin K1 [Mephyton]) for periods of 2 to 91 months. There was one major regression, one partial regression, and three instances of tumor growth arrest over periods up to 8 years. Seven patients were treated with nonsteroid anti-inflammatory drugs concurrent with or after testolactone or tamoxifen. There were five major regressions and one partial regression with extensive central necrosis of an enormous intra-abdominal tumor. The last patient has been treated for only 12 months, with no change in tumor volume. It appears that estrogens function as growth factors for desmoid tumors, and that minimization of these effects inhibits tumor growth in some, but not all, cases. In those instances where antiestrogens were not effective as single agents, the tumors usually responded to subsequent nonsteroid anti-inflammatory drug therapy. Withdrawal of estrogen may be followed by inhibition of transcription of genes that support tumor cell proliferation, and sulindac and indomethacin may augment these effects by inhibiting prostaglandin and cyclic AMP synthesis and the activity of protein kinase C. Warfarin may function as a protonophore to acidify the cytoplasm and prevent the alkalinization that is necessary to initiate DNA synthesis and cell cycle progression, again an impairment of the transcription process.

The use of indomethacin, sulindac, and tamoxifen for the treatment of desmoid tumors associated with familial polyposis

Seven familial polyposis patients with desmoid tumors were treated with indomethacin, sulindac, or tamoxifen either as single agents or in combination. Serial computed tomographic (CT) scan examination was employed for objective measurement of tumor size since physical examination alone was an inaccurate means to evaluate intraabdominal and retroperitoneal desmoids. Only one patient with minimal tumor burden demonstrated a favorable response with complete resolution of an abdominal wall desmoid.

NSAID sulindac and its analog bind RXRalpha and inhibit RXRalpha-dependent AKT signaling

Nonsteroidal anti-inflammatory drugs (NSAIDs) exert their anticancer effects through cyclooxygenase-2 (COX-2)-dependent and independent mechanisms. Here, we report that Sulindac, an NSAID, induces apoptosis by binding to retinoid X receptor-alpha (RXRalpha). We identified an N-terminally truncated RXRalpha (tRXRalpha) in several cancer cell lines and primary tumors, which interacted with the p85alpha subunit of phosphatidylinositol-3-OH kinase (PI3K). Tumor necrosis factor-alpha (TNFalpha) promoted tRXRalpha interaction with the p85alpha, activating PI3K/AKT signaling. When combined with TNFalpha, Sulindac inhibited TNFalpha-induced tRXRalpha/p85alpha interaction, leading to activation of the death receptor-mediated apoptotic pathway. We designed and synthesized a Sulindac analog K-80003, which has increased affinity to RXRalpha but lacks COX inhibitory activity. K-80003 displayed enhanced efficacy in inhibiting tRXRalpha-dependent AKT activation and tRXRalpha tumor growth in animals.

Two stages of cancer prevention with green tea

Cancer chemoprevention is a new and important medical science in its own right. On the occasion of my presentation entitled "Natural agents and cancer chemoprevention" at the 90th AACR Meeting in 1999, I summarized our recent results on cancer prevention with green tea. In this article, the present status of clinical trials supported by the Chemoprevention Branch of the National Cancer Institute in the United States is first described by way of introduction. Although various natural products are now under investigation in phase I clinical trials, green tea has, perhaps, the greatest potential for further development. In order to expand our understanding of the effects of tea polyphenols and green tea, I review their ability to inhibit growth and cause apoptosis of cancer cells, their distribution into target organs and their other cancer-preventing properties. In addition, the paper focuses on the significance of reducing tumor necrosis factor alpha (TNFalpha) gene expression in cells and TNFalpha release from cells as essential activities for cancer prevention. As for the amounts of green tea effective in cancer prevention, I present two results from our Research Institute: a prospective cohort study with over 8000 individuals in Saitama Prefecture revealed that the daily consumption of at least ten Japanese-size cups of green tea resulted in delayed cancer onset, and a follow-up study of breast cancer patients conducted at our Hospital found that stages I and II breast cancer patients consuming over five cups per day experienced a lower recurrence rate and longer disease-free period than those consuming fewer than four cups per day. Thus, I propose here, for the first time, the two-stage approach to analyzing cancer prevention with green tea: cancer prevention before cancer onset and cancer prevention following cancer treatment. As an additional example of cancer prevention with natural agents, kava, a daily beverage in Fiji, is mentioned. All the evidence reminds us of the significance of alternative medicine in practical cancer prevention.

Exisulind (sulindac sulfone) suppresses growth of human prostate cancer in a nude mouse xenograft model by increasing apoptosis

OBJECTIVES

Recent studies have shown that Exisulind, a sulfone metabolite of the nonsteroidal anti-inflammatory drug (NSAID) sulindac, has inhibitory activity in vitro with cultured human prostate cancer cells. To determine whether this effect might be pharmacologically relevant in vivo, we tested whether Exisulind therapy could suppress the growth of human prostate cancer cells in a nude mouse xenograft model.

METHODS

Thirty athymic nude mice were injected subcutaneously in the flank with 1 x 10(7) LNCaP human prostate tumor cells. All mice received a control diet for 21 days. One group of mice was continued on this control diet for an additional 4 weeks, a second group was switched to a diet supplemented with 0.05% Exisulind (40% of maximal tolerated dose [MTD]), and a third group was switched to a diet supplemented with 0.1% Exisulind (80% MTD) for the additional 4 weeks. Tumor growth was measured through the 4-week test period, and subsequently tissue sections from the various groups were tested for apoptotic and dividing cells by quantified use of the TUNEL assay and a bromodeoxyuridine (BrdU) incorporation immunoassay.

RESULTS

Tumors grew by 158%, 24%, and 18% for the control and 0.05% and 0.1% Exisulind groups, respectively (P = 0.02) during the 4-week test period. Immunohistochemical studies on excised tumors showed an increased number of apoptotic bodies in the treated groups versus the control group (P<0.0001) but no change in the number of BrdU positive cells.

CONCLUSIONS

This is the first study to show a direct in vivo effect of an NSAID-derived drug, lacking cyclooxygenase inhibitory activity, in a xenograft model of prostate cancer. Clinical studies to evaluate the effects of Exisulind against prostate cancer in humans are warranted.

A protective effect of sulindac against chemically-induced primary colonic tumours in mice

Sulindac, a non-steroidal anti-inflammatory drug, has been reported to lead to tumour regression in cases of human polyposis coli. We have investigated the effects of this drug on the growth of 1,2-dimethylhydrazine (DMH)-induced mouse colonic tumours. In one experiment, DMH and oral sulindac were administered concurrently to a group of mice for a period of up to 24 weeks, while a control group of animals received DMH only for the same period. Sulindac caused a significant reduction in both the number of mice with colonic tumours and the number of tumours per mouse. In a second experiment, two groups of mice which had already been treated with DMH for 17 weeks received either sulindac or not for 78 days. In this experiment sulindac had no effect. These results demonstrate that sulindac has a protective effect against the chemical induction of colonic tumours in mice, but does not cause the regression of established tumours.

Regression of mouse prostatic intraepithelial neoplasia by nonsteroidal anti-inflammatory drugs in the transgenic adenocarcinoma mouse prostate model

PURPOSE

Epidemiologic studies have revealed a decreased risk of colon cancer among people who have regularly taken cyclooxygenase (COX)-2 inhibitors such as aspirin or other nonsteroidal anti-inflammatory drugs (NSAIDs). Whereas the selective COX-2 inhibitor celecoxib and exisulind, a metabolic product of sulindac, have gained increasing attention as efficacious chemopreventive agents against colon and prostate cancer, not much is known about the underlying molecular targets and mechanisms. Moreover, the side effects of NSAIDs are a major obstacle for large-scale application to the prevention of cancer in humans; for example, in the United States in 1998, there were 16,550 deaths from NSAID-induced gastrointestinal complications. The toxicity associated with these compounds is raising concerns, and more needs to be known about their mode of action and molecular targets.

EXPERIMENTAL DESIGN

We used the transgenic mouse prostate (TRAMP) model, which exhibits similarities with human prostate cancer, including epithelial origin, progression from the PIN stage to adenocarcinoma, and metastasis by a transgene that is hormonally regulated by androgens. In addition to histologically analyzing the PIN lesions of the dorsolateral prostate from TRAMP mice, we delineated the molecular targets and mechanisms of celecoxib and exisulind against mouse PIN lesions. We performed Western blot analysis of the total protein lysate from the tissues of mouse PIN lesions to measure the level of expression of androgen receptor, vascular endothelial growth factor, nuclear factor-kappaB p65, BclII, AKT (total and phosphorylated Ser473), p53, cyclin-dependent kinase inhibitor p21WAF1/CIP1, p27, BAX, and caspase-3 to demonstrate the COX-2-independent mechanism involved in the inhibition of PIN lesions of the dorsolateral prostate by both celecoxib and exisulind.

RESULTS

We found for the first time that (a) both celecoxib and exisulind as dietary supplements induce strong inhibitory effects against prostate cancer at doses of 800 and 500 ppm, respectively, after 16 weeks; (b) the histologic analysis of the dorsolateral prostate after 2 weeks of treatment indicated a reduction of PIN lesions from 75% to 19% with celecoxib and to 16% with exisulind; (c) more importantly, those few PINs and adenocarcinomas in the groups treated with celecoxib or exisulind showed more apoptotic cells, lower levels of proliferating cell nuclear antigen, and a lower number of mitotic cells. To understand the molecular mechanisms involved in the inhibition of PIN lesions, first, we examined the expression of molecular targets involved in angiogenesis and inflammatory processes. It was clearly evident from Western blot analysis of the total protein lysate derived from the dorsolateral prostate tissues with PIN lesions that expression of androgen receptor, vascular endothelial growth factor, nuclear factor-kappaB p65, and BclII is down-regulated more effectively by celecoxib. Down-regulation of AKT protein (total and phosphorylated at Ser473) signaling by celecoxib clearly indicates an inhibition of the survival gene and the pathological process that could otherwise lead to adenocarcinoma.

CONCLUSIONS

Overall, the findings from this study clearly show the effectiveness of celecoxib and exisulind in reducing the PIN lesions by modulating a cascade of molecular targets involved in COX-2-dependent and -independent mechanisms. Whereas these agents are already in clinical trial or in use as chemopreventive agents, findings from this study demonstrate the difference in their mode of action, thus helping us to understand the side effects.