Chemoprevention of colorectal neoplasia.

BACKGROUND: Colorectal cancer is a common and often fatal malignancy. Currently, the modifications that alter disease outcome include early symptom recognition, population screening as well as improved surgical and adjuvant treatments. Preventative strategies have been limited with little evidence that lifestyle changes significantly alter risk. There is however a growing awareness of a potential role for chemoprevention in some patient groups. This study aimed to review the literature associated with chemoprevention in colorectal cancer. METHODS: An electronic literature search of MEDLINE and Embase databases was performed on PubMed for studies detailing the use of chemoprevention agents in colon and rectal cancer. The search was limited to clinical trials on adult humans (>16 years of age) published in English since 1990. RESULTS: The strongest evidence is for non-steroidal anti-inflammatory drugs slowing polyp progression, notably Sulindac and aspirin in patients with familial adenomatous polyposis and hereditary nonpolyposis colorectal cancer, respectively. There is also increasing evidence that continuing use of low-dose aspirin reduces long-term incidence of colorectal cancers. Cyclooxygenase 2 inhibitors also have a potential role but cardiac toxicity currently limits their use. Folic acid, statins, antioxidants, calcium and 5-aminosalicylic acid lack evidence to support their use at present. CONCLUSIONS: Currently, there is not enough evidence to support the implementation of a chemopreventative agent for general use. However, there appears to be a role for aspirin in selected subgroups.

A metagenomic study of the preventive effect of Lactobacillus rhamnosus GG on intestinal polyp formation in ApcMin/+ mice.

AIMS: To investigate the in vivo effects of Lactobacillus rhamnosus GG (LGG) on intestinal polyp development and the interaction between this single-organism probiotic and the gut microbiota therein. METHODS AND RESULTS: The ApcMin/+ mouse model was used to study the potential preventive effect of LGG on intestinal polyposis, while shotgun metagenomic sequencing was employed to characterize both taxonomic and functional changes within the gut microbial community. We found that the progression of intestinal polyps in the control group altered the community functional profile remarkably despite small variation in the taxonomic diversity. In comparison, the consumption of LGG helped maintain the overall functional potential and taxonomic profile in the resident microbes, thereby leading to a 25% decrease of total polyp counts. Furthermore, we found that LGG enriched those microbes or microbial activities related to short-chain fatty acid production (e.g. Roseburia and Coprococcus), as well as suppressed the ones that can lead to inflammation (e.g. Bilophila wadsworthia). CONCLUSIONS: Our study using shotgun metagenomics highlights how single probiotic LGG may exert its beneficial effects and decrease polyp formation in mice by maintaining gut microbial functionality. SIGNIFICANCE AND IMPACT OF THE STUDY: This probiotic intervention targeting microbiota may be used in conjugation with other dietary supplements or drugs as part of prevention strategies for early-stage colon cancer, after further clinical validations in human.

Chemoprevention of hereditary colon cancers: time for new strategies.

Colorectal cancer (CRC) is potentially preventable. Chemoprevention, a focus of research for the past three decades, aims to prevent or delay the onset of cancer through the regression or prevention of colonic adenomas. Ideal pharmacological agents for chemoprevention should be cheap and nontoxic. Although data indicate that aspirin can reduce the risk of CRC in the general population, the highest return from chemopreventive strategies would be expected in patients with the highest risk of developing the disease, particularly those with a defined hereditary predisposition. Despite compelling data showing that a large number of chemopreventive agents show promise in preclinical CRC models, clinical studies have yielded conflicting results. This Review provides a historical and methodological perspective of chemoprevention in familial adenomatous polyposis and Lynch syndrome, and summarizes the current status of CRC chemoprevention in humans. Our goal is to critically focus on important issues of trial design, with particular attention on the choice of appropriate trial end points, how such end points should be measured, and which patients are the ideal candidates to be included in a chemopreventive trial.

The NSAID sulindac is chemopreventive in the mouse distal colon but carcinogenic in the proximal colon.

BACKGROUND AND AIMS: The non-steroidal anti-inflammatory drug sulindac is an effective chemopreventive agent in sporadic colorectal cancer but its potential benefit in mismatch repair deficient cancers remains to be defined. We wanted to determine whether genetic defects that are relevant for colorectal cancer, such as Msh2 or p53 deficiency, would influence the efficiency of sulindac chemoprevention or increase the side effects. METHODS: Msh2 or p53 deficient and wild-type mice received feed containing 160-320 ppm sulindac for up to 25 weeks with or without a concurrent treatment with the carcinogen azoxymethane. Colon tissue was analysed by histopathology and molecular biology methods. RESULTS: We show that sulindac prevented azoxymethane-induced distal colon tumours in all mice. In the proximal colon, however, sulindac induced new inflammatory lesions on the mucosal folds, which further developed into adenocarcinoma in up to 18-25% of the p53 or Msh2 deficient mice but rarely in wild-type mice. This region in the proximal colon was characterised by a distinct profile of pro- and anti-inflammatory factors, which were modulated by the sulindac diet, including upregulation of hypoxia inducible factor 1α and macrophage inflammatory protein 2. CONCLUSIONS: These data show that the sulindac diet promotes carcinogenesis in the mouse proximal colon possibly through chronic inflammation. Sulindac has both beneficial and harmful effects in vivo, which are associated with different microenvironments within the colon of experimental mice. Deficiency for the Msh2 or p53 tumour suppressor genes increases the harmful side effects of long-term sulindac treatment in the mouse colon.

Sulindac sulfide suppresses 5-lipoxygenase at clinically relevant concentrations.

Sulindac is a non-selective inhibitor of cyclooxygenases (COX) used to treat inflammation and pain. Additionally, non-COX targets may account for the drug's chemo-preventive efficacy against colorectal cancer and reduced gastrointestinal toxicity. Here, we demonstrate that the pharmacologically active metabolite of sulindac, sulindac sulfide (SSi), targets 5-lipoxygenase (5-LO), the key enzyme in the biosynthesis of proinflammatory leukotrienes (LTs). SSi inhibited 5-LO in ionophore A23187- and LPS/fMLP-stimulated human polymorphonuclear leukocytes (IC(50) approximately 8-10 microM). Importantly, SSi efficiently suppressed 5-LO in human whole blood at clinically relevant plasma levels (IC(50) = 18.7 microM). SSi was 5-LO-selective as no inhibition of related lipoxygenases (12-LO, 15-LO) was observed. The sulindac prodrug and the other metabolite, sulindac sulfone (SSo), failed to inhibit 5-LO. Mechanistic analysis demonstrated that SSi directly suppresses 5-LO with an IC(50) of 20 muM. Together, these findings may provide a novel molecular basis to explain the COX-independent pharmacological effects of sulindac under therapy.

Nutrition and colon cancer prevention.

PURPOSE OF REVIEW: In spite of improvements in care of colon cancer patients, prevention may enable potential patients to avoid cancer therapy. Although screening is direct and effective, dietary modification or low-risk chemopreventive agents might prevent colon cancer development. In this article, we review recent developments in colon cancer prevention, emphasizing nutrition. RECENT FINDINGS: Epidemiologic findings continue to suggest that diet is related to colon cancer risk. These findings, although, are inconsistent enough to render dietary recommendations premature. An exciting recent discovery is that the combination of diflouromethylornithine and sulindac substantially decreases adenomatous polyp recurrence. Reliance upon clinical trials continues to grow as a means of testing prevention strategies. SUMMARY: Prevention remains an important goal for reducing the burden of colon cancer. Screening has an important role, although it will probably not eliminate all colon cancer. Nutritional modification remains potentially valuable, although research has not yet identified the objects of nutritional intervention. NSAIDs hold promise as chemopreventive agents.

Effect of the non-steroidal anti-inflammatory drug sulindac on colorectal adenomas of uncolectomized familial adenomatous polyposis.

BACKGROUND: The aim of the present study was to elucidate the effect of sulindac on uncolectomized familial adenomatous polyposis (FAP). METHODS: Seven FAP patients (SU group) without proctocolectomy were given sulindac 300 mg/day orally for 12 months. Six FAP patients without sulindac (non-SU group) served as controls. Colorectal lesions were assessed by protrusion index (no. radiolucent areas/cm(2); PI) under barium enema examination and non-polypoid lesion were assessed under chromoscopy prior to and at the end of the observation period. In the SU group, germline adenomatous polyposis coli (APC) mutation was determined by protein truncation test. RESULTS: In the SU group, PI decreased significantly in the distal colon (from 3.0 +/- 1.1 to 1.1 +/- 0.8/cm(2), P < 0.02) and in the proximal colon (from 3.4 +/- 2.4 to 0.9 +/- 1.3/cm(2), P < 0.02). The PI in the non-SU group slightly but significantly increased in the distal colon (from 1.0 +/- 0.8 to 1.2 +/- 0.9/cm(2); P < 0.05) and it remained unchanged in the proximal colon (from 0.6 +/- 0.3 to 0.7 +/- 0.3/cm(2); P > 0.05). Chromoscopy at the end of observation identified non-polypoid lesions in five patients in the SU group, whereas such lesions were not found in the non-SU group (71% vs 0%, P = 0.016). Decrease in PI was not different among distal APC mutation (exons 1-9), proximal APC mutation (exons 10-15) and negative mutation. CONCLUSION: Sulindac reduces colorectal adenomas of protruding type in uncolectomized FAP. The effect of sulindac may be unrelated to genotype of FAP.

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.

Chemoprevention of carcinogenesis in familial tumors.

Among familial cancers, chemoprevention has been studied for familial adenomatous polyposis, hereditary nonpolyposis colorectal cancers, and familial breast cancers. This report reviews the studies on chemoprevention in familial adenomatous polyposis. A large number of clinical trials have been performed using sulindac, a non-steroidal anti-inflammatory drug (NSAID). Sulindac reduces the size and number of large-bowel polyps. However, as yet, it cannot be used for this indication in the clinical setting, because of the frequent occurrence of serious gastrointestinal side effects, and there are a number of patients in whom aggressive tumors developed despite a reduction in the size of polyps. Studies of cyclooxygenase-2 (COX-2) selective inhibitors, with minimal side effects on the digestive tract, are showing promising results. In addition to NSAIDs, clinical trials have been performed using vitamins and dietary components. These show minimal side effects, but their efficacy is still insufficient for clinical use, and further studies are anticipated.

Observation on the therapeutic effect of Shu Feng Huo Luo Pian for treatment of osseous arthritis.

OBJECTIVE: To evaluate the therapeutic effect of Chinese patent drug Shu Feng Huo Luo Pian ([symbol: see text] Pill for Dispelling Wind and Activating Collaterals) for the treatment of osseous arthritis. METHOD: 50 cases of osseous arthritis were divided randomly into two groups, the Shu Feng Huo Luo Pian group (the experimental group), including 30 cases (aged 63.5 +/- 4 years), treated with 2 such pills, p.o., bid; and the control group, including 19 cases (aged 63 +/- 5 years), treated with Sulindac 0.2 g, p.o., bid. The two groups were all supplemented by medication of calcium Caltrate D 0.6 g, p.o., qd. The above-mentioned medications were administered for 2 courses, 2 weeks constituting a course. RESULT: The total effective rate of the experimental group evaluated by the doctors was 83.3%, and that evaluated by the patients was 90%, with mild side effects. CONCLUSION: Shu Feng Huo Luo Pian is an effective Chinese patent drug for treating osseous arthritis, with less and mild side effects.

[Chemoprevention of colorectal cancer]. / La chimioprévention du cancer colorectal.

A NEW CONCEPT: Chemoprevention of cancer consists in the administration of chemical agents to prevent or inhibit carcinogenesis. This strategy can be applied at any stage of carcinogenesis. ASSESSMENT: The development of such agents relies on classical bases: phases I, II and III. The approach consists in assessing the effect of the substance tested in patients with history of resected adenomas of the colon and at high risk of relapse and/or family risk of colon cancer. THE PRINCIPLE AGENTS UNDER ASSESSMENT: Are aspirin, type 2 cyclo-oxygenase inhibitors, calcium, folic acid, certain vitamins, hormone replacement therapy for menopausal women and difluoromethylornithine (DFMO).

Synergistic effects of (-)-epigallocatechin gallate with sulindac against colon carcinogenesis of rats treated with azoxymethane.

(-)-Epigallocatechin gallate (EGCG), a major constituent of green tea, has been shown to exhibit anti-cancer activity. Sulindac is also well known as a cancer-preventive agent against colon cancer, but its usage is restricted because of its adverse effects, as exemplified by gastrointestinal bleeding. In the present study, we examined whether a combination of EGCG and sulindac shows synergistic effects for cancer-preventive activity for rat colon carcinogenesis induced by azoxymethane (AOM); we examined the number of aberrant crypt foci (ACF) representing preneoplastic lesions, the argyrophilic nucleolar organizer region (AgNOR) as an indicator of cell proliferation, and the incidence of apoptosis. The AOM treatment induced an average of 46.2+/-4.9 ACF/colon, and sulindac and EGCG significantly reduced the incidence of ACF/colon to 21.4+/-3.4 and 19.5+/-5.8, respectively (P<0.01). The co-treatment with EGCG and sulindac resulted in significantly reduced ACF formation (10.0+/-3.2; P<0.01). The results of the AgNOR analysis indicated that the treatment with EGCG and/or sulindac suppressed AOM-induced cell proliferation. The present results also revealed that the combination of EGCG and sulindac synergistically enhanced apoptosis significantly (P<0.01). Thus, our findings suggest that EGCG with sulindac synergistically suppresses ACF formation by enhancing apoptosis and, therefore, that EGCG is a suitable candidate for use in combination with cancer-preventive agents, such as sulindac, to reduce their adverse effects.

Cyclooxygenase inhibitors are potent sensitizers of prostate tumours to hyperthermia and radiation.

It has previously been demonstrated that hyperthermia can activate prostaglandin synthesis and that prostaglandins are protective against hyperthermia. This study examined the use of inhibitors of prostaglandin synthesis on the response of prostate tumours to hyperthermia. The non-steroidal anti-inflammatory drugs (NSAID) ibuprofen and sulindac, known cyclooxygenase inhibitors that inhibit prostaglandin production, were effective hyperthermia sensitizers and augmented growth delay of DU-145 and PC-3 prostate tumours to combined radiation and hyperthermia treatment protocols. Pre-treatment of mice with ibuprofen and sulindac at hyperthermia sensitizing doses resulted in significant (p < 0.01) inhibition of hyperthemia-induced serum prostaglandin E2. These findings indicate that NSAID may have both sensitizing effects on prostate tumour growth and may function by inhibiting prostaglandin synthesis.

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.

Synergistic effects of (--)-epigallocatechin gallate with (--)-epicatechin, sulindac, or tamoxifen on cancer-preventive activity in the human lung cancer cell line PC-9.

The study on incorporation of [3H](-)-epigallocatechin gallate (EGCG) into human lung cancer cell line PC-9 indicated that the [3H]EGCG incorporation was significantly enhanced by (-)-epicatechin, an inert tea polyphenol without a galloyl moiety. (-)-Epicatechin enhanced apoptosis, growth inhibition of PC-9 cells, and inhibition of tumor necrosis factor-alpha release from BALB/c-3T3 cells by EGCG and other tea polyphenols with a galloyl moiety in a dose-dependent manner. Moreover, the effects of EGCG on induction of apoptosis were also synergistically enhanced by other cancer-preventive agents, such as sulindac and tamoxifen. This paper reports significant evidence that whole green tea is a more reasonable mixture of tea polyphenols for cancer prevention in humans than EGCG alone and that it is even more effective when it is used in combination with other cancer preventives.

Colorectal cancer--chemoprevention.

Colorectal cancer is the second leading cause of death from cancer in The United States. During the last fifteen years, emphasis has been placed on identification of high risk patients and families and outline of appropriate surveillance regimens for normal and high risk patients for colorectal cancer. Parallel to this effort, abundant clinical data has been accumulated that chemoprevention of colorectal cancer with nonsteroidals and aspirin may be possible. Interruption of prostaglandin metabolism appears to be one of the mechanisms of action but not the only therapeutic arm. Currently, sulindac, aspirin, calcium and selenium supplementation are attractive recommendations to at risk patients awaiting results of clinical trials. Other agents in development add excitement to the concept of colorectal cancer chemoprevention.

Sulindac causes rapid regression of preexisting tumors in Min/+ mice independent of prostaglandin biosynthesis.

Several lines of evidence strongly link prostaglandins (PGs) and leukotrienes (LTs) to cancer of the intestine. Several studies have reported a 40-50% reduction in mortality from colorectal cancer in individuals who routinely consume nonsteroidal anti-inflammatory drugs, possibly by inhibiting cyclooxygenase activity. However, the role of eicosanoids in this process is still unclear. The heterozygote Min/+ mouse model, like patients with familial adenomatous polyposis, carries a nonsense mutation in the adenomatous polyposis coli (APC) gene that results in the spontaneous development of intestinal adenomas (100% incidence). This study investigated the association between eicosanoid biosynthesis, intestinal tumor load, and the chemotherapeutic effect of the nonsteroidal anti-inflammatory drug sulindac during early and preexisting phases of tumor growth and development as well as residual effects after drug withdrawal. Administration of sulindac (320 ppm) to Min/+ mice reduced the tumor number by 95% but did not alter the levels of PGE2 and LTB4 in intestinal tissues. Increasing PGE2 and LTB4 levels by 44% with dietary arachidonic acid supplementation had no effect on tumor number or size. When sulindac was added to the arachidonic acid-supplemented diet, tumor number was reduced by 82%, whereas eicosanoid levels remained elevated. In Min/+ mice with established tumors, treatment with sulindac for 4 days reduced tumor number by 75%, and continual administration of sulindac was necessary to maintain a reduced tumor load. In summary, alterations in eicosanoid formation were not correlated with tumor number or size in the Min/+ mouse model; thus, the antitumor effect of sulindac seems to be PG independent.

The economic consequences of NSAID-induced gastropathy: the French context.

The costs of treating gastroduodenal ulcers caused by nonsteroidal anti-inflammatory drugs (NSAIDs) are shown to increase the total cost of NSAID treatment to the Assurance-Maladie, the French national health insurance system. This increased cost is termed the iatrogenic cost factor, and is defined as the ratio of the shadow price of an NSAID to its reimbursed cost. The shadow price is calculated from estimates of the incidence of NSAID-induced gastropathies, the cost of the drug, and the hospital and ambulatory costs of treating the gastropathies. The resulting iatrogenic cost factors are estimated as 1.36 for naproxen, 1.48 for sulindac, 1.65 for diclofenac, 1.67 for piroxicam, 2.00 for ketoprofen, and 2.12 for etodolac.

The pro-drug sulindac may reduce the risk of intestinal damage associated with the use of conventional non-steroidal anti-inflammatory drugs.

To test the hypothesis that administration of a non-steroidal anti-inflammatory drug formulated as a pro-drug, inactive as a cyclooxygenase inhibitor until after absorption, might cause less intestinal damage than conventional non-steroidal anti-inflammatory drugs, intestinal permeation to 51Cr-EDTA and mannitol was assessed in healthy volunteers before and after oral treatment for 1 week with either the pro-drug sulindac or the conventional non-steroidal anti-inflammatory drug indomethacin. Indomethacin, but not sulindac, significantly increased intestinal permeation to 51Cr-EDTA and reduced haemoglobin and haematocrit; neither affect mannitol permeation.