Ursodeoxycholate/Sulindac combination treatment effectively prevents intestinal adenomas in a mouse model of polyposis

Human Gut Microbiome and Liver Diseases: From Correlation to Causation

The important role of human gut microbiota in liver diseases has long been recognized as dysbiosis and the translocation of certain microbes from the gut to liver. With the development of high-throughput DNA sequencing, the complexity and integrity of the gut microbiome in the whole spectrum of liver diseases is emerging. Specific patterns of gut microbiota have been identified in liver diseases with different causes, including alcoholic, non-alcoholic, and virus induced liver diseases, or even at different stages, ranging from steatohepatitis, fibrosis, cirrhosis, to hepatocellular carcinoma. At the same time, the mechanism of how microbiota contributes to liver diseases goes beyond the traditional function of the gut–liver axis which could lead to liver injury and inflammation. With the application of proteomics, metabolomics, and modern molecular technologies, more microbial metabolites and the complicated interaction of microbiota with host immunity come into our understanding in the liver pathogenesis. Germ-free animal models serve as a workhorse to test the function of microbiota and their derivatives in liver disease models. Here, we review the current evidence on the relationship between gut microbiota and liver diseases, and the mechanisms underlying this phenotype. In addition to original liver diseases, gut microbiota might also affect liver injury in systemic disorders involving multiple organs, as in the case of COVID-19 at a severe state. A better understanding of the gut microbial contribution to liver diseases might help us better benefit from this guest–host relationship and pave the way for novel therapies.

Role of bile acids in colon carcinogenesis

Bile acids (BAs) are cholesterol derivatives synthesized in the liver and then secreted into the intestine for lipid absorption. There are numerous scientific reports describing BAs, especially secondary BAs, as strong carcinogens or promoters of colon cancers. Firstly, BAs act as strong stimulators of colorectal cancer (CRC) initiation by damaging colonic epithelial cells, and inducing reactive oxygen species production, genomic destabilization, apoptosis resistance, and cancer stem cells-like formation. Consequently, BAs promote CRC progression via multiple mechanisms, including inhibiting apoptosis, enhancing cancer cell proliferation, invasion, and angiogenesis. There are diverse signals involved in the carcinogenesis mechanism of BAs, with a major role of epidermal growth factor receptor, and its down-stream signaling, involving mitogen-activated protein kinase, phosphoinositide 3-kinase/Akt, and nuclear factor kappa-light-chain-enhancer of activated B cells. BAs regulate numerous genes including the human leukocyte antigen class I gene, p53, matrix metalloprotease, urokinase plasminogen activator receptor, Cyclin D1, cyclooxygenase-2, interleukin-8, and miRNAs of CRC cells, leading to CRC promotion. These evidence suggests that targeting BAs is an efficacious strategies for CRC prevention and treatment.

The role of bile acids in cellular invasiveness of gastric cancer

Background

Bile acids have been implicated in the development of digestive tract malignancy by epidemiological, clinical and animal studies. The growth and transformation signaling by most of the bile acids is thought to be related to the induced cyclooxygenase-2 (COX-2) expression and increased production of prostaglandin E2 (PGE2). The highly hydrophobic bile acids such as chenodeoxycholic acid (CD) and deoxycholic acid can promote carcinogenesis and stimulate the invasion of colon cancer cells. On the contrary, ursodeoxycholic acid (UDCA), a less hydrophobic stereoisomer of CD, inhibits proliferation and induces apoptosis in colon cancer cells. We examined the effects of bile acid on human gastric cancer cells MKN-74.

Methods

Early-passage human gastric cancer MKN-74 cells were used for drug treatment, preparation of whole cell lysates, subcellular extracts and Western blot analysis. The levels of PGE2 released by the cells were measured by enzyme inummoassay to indicate COX-2 enzymatic activity. Cellular invasion assay was performed in Boyden chamber.

Results

Exposure of CD led to activation of protein kinase C (PKC) alpha, increased COX-2 expression and increased PGE2 synthesis. The induced COX-2 protein expression could be detected within 4 h exposure of 200 μM CD, and it was dose- and time-dependent. PGE2 is the product of COX-2, and has been reported to cause tumor invasion and angiogenesis in animal study. Safingol (SAF), a PKC inhibitor, suppressed the COX-2 protein expression and PGE2 production by CD in MKN-74. Furthermore, UDCA suppressed PGE2 production by CD but did not affect COX-2 protein expression induced by CD. Using a Boyden chamber invasion assay, both SAF and UDCA impeded CD induced tumor invasiveness of MKN-74 by 30–50%.

Conclusions

Our results indicate that signaling of hydrophobic bile acid such as CD in gastric cancer cells is through PKC activation and COX-2 induction, which leads to increased cellular invasion. By perturbing the bile acid pool, UDCA attenuates CD-induced PGE2 synthesis and tumor invasiveness.

The Association of Ursodeoxycholic Acid Use With Colorectal Cancer Risk: A Nationwide Cohort Study

Data from preclinical studies suggest that ursodeoxycholic acid (UDCA) has a chemopreventive effect on colorectal cancer (CRC) development, but no large observational study has examined this possibility. The aim of this study was to investigate the association of UDCA use with CRC risk in a nationwide population-based cohort. This nationwide population-based cohort study used data from the Taiwan National Health Insurance Research Database for the period from 2000 through 2010. This study included data from 7119 Taiwanese adults who received ≥28 cumulative defined daily doses (cDDDs) of UDCA and 14,238 patients who did not receive UDCA (<28 cDDDs). UDCA nonusers were matched 1:2 for age, sex, enrollment date, and presence of chronic liver disease, viral hepatitis, cholelithiasis, and alcoholic liver disease. The 2 cohorts were followed until December 31, 2010 or occurrence of CRC. Cox proportional hazards regression with robust Sandwich variance estimator, which can cooperate with matching design, was used to examine the association between UDCA use and CRC risk. During 109,312 person-years of follow-up (median, 5 years), 121 patients had newly diagnosed CRC: 28 UDCA users (76.7 per 100,000 person-years) and 93 nonusers (127.7 per 100,000 person-years) (log-rank test, P = 0.0169). After multivariate adjustment for age, UDCA use was associated with a reduced risk of CRC (hazard ratio, 0.60; 95% confidence interval [CI], 0.39-0.92). The adjusted hazard ratios were 0.55 (95% CI, 0.35-0.89), 0.89 (95% CI, 0.36-2.20), and 0.63 (95% CI, 0.16-2.53) for patients with 28 to 180, 181 to 365, and >365 cDDDs, respectively, relative to nonusers. UDCA use was associated with reduced risk of CRC in a cohort mainly comprising patients with chronic liver diseases. However, further studies are needed to determine the optimal dosage of UDCA.

Duodenal mucosal risk markers in patients with familial adenomatous polyposis: effects of celecoxib/ursodeoxycholic acid co-treatment and comparison with patient controls

Background

Familial adenomatous polyposis (FAP) is a disease characterized by the development of hundreds to thousands of adenomatous polyps in the colorectum early in life. Virtually all patients with FAP will develop colorectal cancer before the age of 40 to 50 years, unless prophylactic colectomy is performed, which significantly improves their prognosis. The mortality pattern has changed and duodenal cancer now is one of the main cancer-related causes of death in these patients. Practically all patients with FAP develop premalignant duodenal adenomas, which may develop to duodenal cancer in approximately 3-7% of patients. Duodenal cancer in patients with FAP has a poor prognosis. The clinical challenge is to identify patients at high-risk for duodenal carcinoma. Chemoprevention would be desirable to avoid duodenectomy. The main goal of this study is to identify risk markers in normal duodenal mucosa of patients with FAP, that could help identify patients at increased risk for malignant transformation.

Methods

Messenger RNA (mRNA) levels of glutathione S-transferase A1 (GSTA1), glutathione S-transferase P1 (GSTP1), KIAA1199, E-cadherin, peroxisome proliferative activated receptor δ (PPARδ), caspase-3, cyclin D1, β-catenin, and cyclooxygenase-2 (COX-2) were measured in duodenal mucosa, using the QuantiGene 2.0 Plex assay. Levels in normal appearing mucosa of patients with FAP (n = 37) were compared with levels in non-FAP patient controls (n = 16). In addition, levels before and after treatment with either celecoxib & ursodeoxycholic acid (UDCA, n = 14) or celecoxib & placebo (n = 13) were evaluated in patients with FAP.

Results

mRNA levels of glutathione S-transferase A1 (28.16% vs. 38.24%, p = 0.008) and caspase-3 (3.30% vs. 5.31%, p = 0.001) were significantly lower in patients with FAP vs. non-FAP patient controls, respectively. COX-2 mRNA levels in normal duodenal mucosa of patients with FAP were found to be unexpectedly low. None of the potential risk markers was influenced by celecoxib or celecoxib & UDCA.

Conclusions

Protection against toxins and carcinogens (GSTA1) and apoptosis (caspase-3) is low in patients with FAP, which could contribute to increased susceptibility for malignant transformation of duodenal mucosa.

Trial registration

http://ClinicalTrials.gov number NCT00808743

Ursodeoxycholic acid counteracts celecoxib in reduction of duodenal polyps in patients with familial adenomatous polyposis: a multicentre, randomized controlled trial

Background

Due to prophylactic colectomy, mortality in patients with familial adenomatous polyposis (FAP) has changed, with duodenal cancer currently being the main cause of death. Although celecoxib reduces duodenal polyp density in patients with FAP, its long-term use may increase the risk of cardiovascular events and alternatives need to be explored. Preclinical studies suggest that the combination of celecoxib with ursodeoxycholic acid (UDCA) is a potentially effective strategy. We performed a randomized, double-blind, placebo-controlled trial to investigate the effect of celecoxib and UDCA co-treatment on duodenal adenomatosis in patients with FAP.

Methods

Patients with FAP received celecoxib (400 mg twice daily) and UDCA (1000-2000 mg daily, ~20-30 mg/kg/day, n=19) or celecoxib and placebo (n=18) orally for 6 months. Primary outcome was drug efficacy, assessed by comparing duodenal polyp density at pre- and post-intervention by blinded review of endoscopic recordings. As secondary outcomes, cell proliferation, apoptosis, and COX-2 levels in normal duodenal mucosa were assessed by immunohistochemistry or real-time quantitative polymerase chain reaction.

Results

In intention-to-treat analysis, deceased polyp density was observed after celecoxib/placebo treatment (p=0.029), whereas increased polyp density was observed after celecoxib/UDCA treatment (p=0.014). The difference in change in duodenal polyp density was statistically significant between the groups (p=0.011). No changes in secondary outcomes were observed. Thirty patients (81%) reported one or more adverse events, 16 patients (84%, Common Toxicity Criteria for Adverse Events version 3.0 (CTCAE) grade 1–3) treated with celecoxib/UDCA and 14 patients (78%, CTCAE grade 1–2) treated with celecoxib/placebo. Nine patients (24%) discontinued intervention prematurely, 5 patients (26%) treated with celecoxib/UDCA and 4 patients (22%) treated with celecoxib/placebo.

Conclusions

Celecoxib reduces duodenal polyp density in patients with FAP, and unexpectedly, high dose UDCA co-treatment counteracts this effect. The benefit of long term use of celecoxib for duodenal cancer prevention needs to be weighed against the (risk of) adverse events.

Trial registration

http://ClinicalTrials.gov, identifier NCT00808743

Chemoprevention of colorectal cancer with ursodeoxycholic acid: pro

Colorectal cancer is the third and second most common cancer among men and women, respectively, in France. Interest in the chemoprevention of colorectal cancer has increased over the last two decades. Experimental data strongly suggest that ursodeoxycholic acid (UDCA) may have chemopreventative actions in colorectal cancer. UDCA is able to inhibit tumor development in azoxymethane and in dextran-related colitis models. In high-risk populations such as subjects with previous colorectal adenoma removal or inflammatory bowel disease, five out of 10 published studies suggested beneficial effects with UDCA on colonic carcinogenesis. In the azoxymethane model, UDCA inhibited tumor development by counteracting the tumor-promoting effects of secondary bile acids such as deoxycholic acid (DCA). The opposing effects of UDCA and DCA on lipid raft composition may be central to their effects on colonic tumorigenesis. Differential effects of DCA and UDCA on growth factor and inflammatory signals involved in colorectal carcinogenesis, such as epidermal growth factor receptor (EGFR) signaling and COX-2 expression, very likely mediate their opposing effects on colonic tumor promotion and tumor inhibition, respectively.

Celecoxib and tauro-ursodeoxycholic acid co-treatment inhibits cell growth in familial adenomatous polyposis derived LT97 colon adenoma cells

Chemoprevention would be a desirable strategy to avoid duodenectomy in patients with familial adenomatous polyposis (FAP) suffering from duodenal adenomatosis. We investigated the in vitro effects on cell proliferation, apoptosis, and COX-2 expression of the potential chemopreventives celecoxib and tauro-ursodeoxycholic acid (UDCA). HT-29 colon cancer cells and LT97 colorectal micro-adenoma cells derived from a patient with FAP, were exposed to low dose celecoxib and UDCA alone or in combination with tauro-cholic acid (CA) and tauro-chenodeoxycholic acid (CDCA), mimicking bile of FAP patients treated with UDCA. In HT-29 cells, co-treatment with low dose celecoxib and UDCA resulted in a decreased cell growth (14-17%, p<0.01). A more pronounced decrease (23-27%, p<0.01) was observed in LT97 cells. Cell growth of HT-29 cells exposed to 'artificial bile' enriched with UDCA, was decreased (p<0.001), either in the absence or presence of celecoxib. In LT97 cells incubated with 'artificial bile' enriched with UDCA, cell growth was decreased only in the presence of celecoxib (p<0.05). No clear evidence was found for involvement of proliferating cell nuclear antigen, caspase-3, or COX-2 in the cellular processes leading to the observed changes in cell growth. In conclusion, co-treatment with low dose celecoxib and UDCA has growth inhibitory effects on colorectal adenoma cells derived from a patient with FAP, and further research on this combination as promising chemopreventive strategy is desired.

Chemoprevention in familial adenomatous polyposis

Familial adenomatous polyposis (FAP) predictably leads to adenomas and eventual adenocarcinomas in the lower gastrointestinal tract and less frequently, the upper gastrointestinal tract. Chemopreventive strategies have been studied in FAP patients to delay the development of adenomas in the upper and lower gastrointestinal tract, as well as to prevent recurrence of adenomas in the retained rectum of patients after prophylactic surgery with colectomy and ileorectal anastamosis (IRA). The nonsteroidal anti-inflammatory drug (NSAID) sulindac and selective cyclooxygenase-2 (COX-2) inhibitor celecoxib reduce polyposis of the retained rectum after colectomy with IRA. Reports of cardiovascular risks of some NSAIDs and selective COX-2 inhibitors have led to promising studies of lower doses in combination with ursodeoxycholic acid, statin, and difluoromethylornithine. Curcumin and eicosapentaenoic acid show efficacy in small clinical trials of FAP chemoprevention. This article will review the concept of chemoprevention and the current clinical literature in FAP chemoprevention.

Chemoprevention of colorectal cancer: a role for ursodeoxycholic acid, folate and hormone replacement treatment?

Chemoprevention of colorectal cancer has been an intense focus of research for many years. Among the possible candidate agents, ursodeoxycholic acid, folate, and hormone replacement therapy have been recently investigated with conflicting data. Experimental evidence shows that UDCA, folate and HRT target critical molecular events important for colon carcinogenesis. In animal models of sporadic, familial and inflammatory-associated cancers, they have shown to reduce colonic neoplasms. Observational studies have shown compelling evidence of possible protective effects of all three agents. However, randomised-controlled studies have yielded disappointing results, raising the issues of possible harm rather than protective effect for some of them. In this review experimental and clinical data on UDCA, folate and HRT as potential chemopreventive agents are discussed.

Chemoprevention for advanced CR neoplasia

Colorectal cancer (CRC) is a major health concern worldwide. In 2011 1,200,000 new cases are predicted and half of them are going to die from the disease. CRC carcinogenesis is a multi-step process that spans over 10-20 years, providing a window of opportunity for effective intervention. CRC can be prevented by life style modification and screening program. However, although these strategies are standard clinical practice, their impact is limited due to low adherence. The number of deaths due to CRC remains alarming high, and makes CRC prevention a paramount. Chemoprevention interferes with the carcinogenesis process by targeting key molecular pathways. It involves the use of a variety of natural or chemical compounds that can delay, prevent or even reverse the adenoma to carcinoma sequence. Numerous chemopreventive agents have been studied but the most efficient are the NSAID group of agents. Much of their efficacy and toxicity has been attributed to their potent inhibition of the cyclooxygenase (COX) enzymes. Chemoprevention has the potential to represent a cost-effective intervention, particularly when targeted at intermediate-risk populations, ages 61-70, following polypectomy. Chemoprevention in this setting is as very important as polyp recurrence in this population can be as high as 50%, even with surveillance colonoscopy every 1-3 years. The most challenging task is to find the proper place for these interventions in the entire effort of general wellbeing. Subjects are likely to be more adherent to prescribed regimens if cancer prevention may be combined with a cardiovascular and Alzheimer prophylaxis. Subjects with a normal colon or non advanced adenomas can be safely monitored with surveillance colonoscopy every 5-10 years. The ideal chemopreventive agent remains to be discovered with great emphasis on the need not to harm. Possibly, combinations of agents will maximize effectiveness while limiting drug toxicity. Finally, personalized approaches would include the ability to predict risk, as well as benefit for a specific individual based on specific SNP's or other genetic profiles.

The use of animal models for cancer chemoprevention drug development

Animal models currently are used to assess the efficacy of potential chemopreventive agents, including synthetic chemicals, chemical agents obtained from natural products, and natural product mixtures. The observations made in these models as well as other data are then used to prioritize agents to determine which are qualified to progress to clinical chemoprevention trials. Organ-specific animal models are employed to determine which agents or classes of agents are likely to be the most effective at nontoxic doses to prevent organ-specific forms of cancer. These results are then used to target specific organs in high-risk populations in clinical trials. The animal models used are either carcinogen-induced with carcinogens specific for particular organ sites or they are transgenic/mutant animals with insertions, deletions, or mutations at targeted gene sites known to enhance cancers in a specific organ. Animal tumor models with characteristics favorable to chemoprevention studies are available for cancers of the lung, colon, skin, bladder, mammary, prostate, head and neck, esophagus, ovary, and pancreas. In addition to single-agent dose-response testing, such models are frequently used for testing combinations of agents, testing different routes of administration, evaluating surrogate endpoint biomarkers, and generating initial pharmacokinetics and toxicology data. For some of the more standard animal models there is significant correlation with human chemopreventive trial results. There are a growing number of positive human chemoprevention trials that have used agents or combinations that were positive in animal testing. There have been fewer negative human clinical trials, but their results again correlate with negative animal results. Clearly the validation of animal models to predict the efficacy of agents in human clinical trials will await further human data on positive and negative outcomes with chemopreventive agents. Whether validated or not, animal efficacy data remain central to the clinical trial decision-making process.

Ursodeoxycholic acid and chemoprevention of colorectal cancer

Colorectal cancer is respectively the third and second most common cancer among men and women in France. Interest in chemoprevention for colorectal cancer has increased over the last two decades. Beside non-steroidal anti-inflammatory drugs, ursodeoxycholic acid (UDCA) may have chemopreventive action in colorectal cancer with a likely better tolerance. In high-risk populations such as patients with inflammatory bowel disease or prior colorectal adenoma or carcinoma, retrospective and prospective studies have suggested a beneficial effect of UDCA. In azoxymethane model, UDCA inhibits tumor development by countering the tumor-promoting effects of secondary bile acids, such as deoxycholic acid (DCA). The opposing effects of UDCA and DCA on lipid raft composition may be central to their effects on colonic tumorigenesis. Differential effects of DCA and UDCA on growth factor and inflammatory signals involved in colorectal carcinogenesis, such as epidermal growth factor receptors (EGFR) signaling and Cox-2 expression, likely mediate their opposing effects on colonic tumor promotion and tumor inhibition, respectively.

Sodium taurocholate inhibits intestinal adenoma formation in APCMin/+ mice, potentially through activation of the farnesoid X receptor

In light of clinical and biological evidence that bile constituents exert preventive effects against colorectal cancer, we evaluated the influence of oral bilirubin and sodium taurocholate (NaTC) on intestinal tumor formation in APC(Min/+) mice. Mice received bilirubin and/or bovine serum albumin (BSA) and NaTC in the drinking water for 8 weeks, after which the number, size and location of intestinal adenomas were determined. Tissue specimens were analyzed by light microscopy, TUNEL staining, immunohistochemistry for beta-catenin and Ki-67 and quantitative polymerase chain reaction for farnesoid X receptor (FXR)-dependent gene expression. Colon tumor formation also was assessed in azoxymethane (AOM)-treated hyperbilirubinemic Gunn (j/j) and wild-type (+/+) rats. Compared with untreated APC(Min/+) mice, the mean number of intestinal adenomas was markedly lower in both bilirubin (10.5 +/- 0.9 versus 37.0 +/- 5.2; +/-SEM; P < 0.001) and NaTC plus BSA (14.3 +/- 5.4; P = 0.01)-treated animals. Both treatment groups exhibited reduced levels of cellular proliferation in the ileum (by Ki-67 staining), but no differences in TUNEL staining or the percentage of beta-catenin-positive crypts. Bilirubin feeding reduced intestinal inducible nitric oxide synthase expression, but did not alter adenoma multiplicity in APC(Min/+) mice or in AOM-treated j/j versus +/+ rats. Mice receiving NaTC manifested increased intestinal expression of the FXR-regulated genes, Shp, FGF15 and IBABP, and a concomitant decrease in cyclin D1 message. Administering NaTC to APC(Min/+) mice causes a marked reduction in intestinal adenomas. We postulate that this effect is mediated through activation of FXR, leading to increased Shp expression and consequent downregulation of cyclin D1.

Protective effects of glycoursodeoxycholic acid in Barrett's esophagus cells

Barrett's esophagus (BE) is a premalignant condition associated with the development of esophageal adenocarcinoma (EAC). Previous studies have implicated hydrophobic bile acids and gastric acid in BE and EAC pathogenesis. In this study, we tested the hypothesis that DNA damage, cytotoxicity and oxidative stress induced by bile acids and gastric acid can be attenuated by the cytoprotective, hydrophilic bile acid glycoursodeoxycholic acid (GUDCA). Non-dysplastic BE cells were exposed for 10 min to pH 4 and/or bile acid cocktail or to pH 4 and a modified cocktail consisting of a mixture of bile acids and GUDCA. DNA damage was evaluated by the comet assay; cell viability and proliferation were measured by trypan blue staining and the MTS assay; reactive oxygen species (ROS) were measured using hydroethidium staining; oxidative DNA/RNA damage was detected by immunostaining with antibody against 8-OH-dG; thiol levels were measured by 5-chloromethylfluorescein diacetate (CMFDA) staining; and the expression of antioxidant proteins was evaluated by western blotting. DNA damage and oxidative stress were significantly increased, while thiol levels were decreased in BE cells treated with pH 4 and bile acid cocktail compared with cells treated with pH 4 alone or untreated cells. Bile acids and low pH also significantly decreased cell proliferation. Expression of the antioxidant enzymes, MnSOD and CuZnSOD, was elevated in the cells treated with bile acids and low pH. When GUDCA was included in the medium, all these effects of pH 4 and bile acids were markedly reduced. In conclusion, treatment of BE cells with acidified medium and a bile acid cocktail at physiologically relevant concentrations induces DNA damage, cytotoxicity, and ROS. The cytoprotective bile acid, GUDCA, inhibits these deleterious effects by inhibiting oxidative stress.

Familial adenomatous polyposis

Familial adenomatous polyposis (FAP) is characterized by the development of many tens to thousands of adenomas in the rectum and colon during the second decade of life. FAP has an incidence at birth of about 1/8,300, it manifests equally in both sexes, and accounts for less than 1% of colorectal cancer (CRC) cases. In the European Union, prevalence has been estimated at 1/11,300-37,600. Most patients are asymptomatic for years until the adenomas are large and numerous, and cause rectal bleeding or even anemia, or cancer develops. Generally, cancers start to develop a decade after the appearance of the polyps. Nonspecific symptoms may include constipation or diarrhea, abdominal pain, palpable abdominal masses and weight loss. FAP may present with some extraintestinal manifestations such as osteomas, dental abnormalities (unerupted teeth, congenital absence of one or more teeth, supernumerary teeth, dentigerous cysts and odontomas), congenital hypertrophy of the retinal pigment epithelium (CHRPE), desmoid tumors, and extracolonic cancers (thyroid, liver, bile ducts and central nervous system). A less aggressive variant of FAP, attenuated FAP (AFAP), is characterized by fewer colorectal adenomatous polyps (usually 10 to 100), later age of adenoma appearance and a lower cancer risk. Some lesions (skull and mandible osteomas, dental abnormalities, and fibromas on the scalp, shoulders, arms and back) are indicative of the Gardner variant of FAP. Classic FAP is inherited in an autosomal dominant manner and results from a germline mutation in the adenomatous polyposis (APC) gene. Most patients (~70%) have a family history of colorectal polyps and cancer. In a subset of individuals, a MUTYH mutation causes a recessively inherited polyposis condition, MUTYH-associated polyposis (MAP), which is characterized by a slightly increased risk of developing CRC and polyps/adenomas in both the upper and lower gastrointestinal tract. Diagnosis is based on a suggestive family history, clinical findings, and large bowel endoscopy or full colonoscopy. Whenever possible, the clinical diagnosis should be confirmed by genetic testing. When the APC mutation in the family has been identified, genetic testing of all first-degree relatives should be performed. Presymptomatic and prenatal (amniocentesis and chorionic villous sampling), and even preimplantation genetic testing is possible. Referral to a geneticist or genetic counselor is mandatory. Differential diagnoses include other disorders causing multiple polyps (such as Peutz-Jeghers syndrome, familial juvenile polyps or hyperplastic polyposis, hereditary mixed polyposis syndromes, and Lynch syndrome). Cancer prevention and maintaining a good quality of life are the main goals of management and regular and systematic follow-up and supportive care should be offered to all patients. By the late teens or early twenties, colorectal cancer prophylactic surgery is advocated. The recommended alternatives are total proctocolectomy and ileoanal pouch or ileorectal anastomosis for AFAP. Duodenal cancer and desmoids are the two main causes of mortality after total colectomy, they need to be identified early and treated. Upper endoscopy is necessary for surveillance to reduce the risk of ampullary and duodenal cancer. Patients with progressive tumors and unresectable disease may respond or stabilize with a combination of cytotoxic chemotherapy and surgery (when possible to perform). Adjunctive therapy with celecoxib has been approved by the US Food and Drug Administration and the European Medicines Agency in patients with FAP. Individuals with FAP carry a 100% risk of CRC; however, this risk is reduced significantly when patients enter a screening-treatment program.

Colon cancer: preventive agents and the present status of chemoprevention

BACKGROUND

Colorectal cancer (CRC) is one of the most common cancers worldwide and a prevalent cause of morbidity and mortality. CRC has a natural history of transition from a precursor lesion, ie adenomatous polyp to cancer, that spans over 10 to 15 years providing an extended opportunity for intervention and cancer prevention. Suppression of the carcinogenic process by use of pharmacological or natural agents is the cornerstone of chemoprevention.

OBJECTIVES

The aim of this review was to give an up-to-date overview on the different agents that had been studied, over the last decade, as chemopreventive agents and the current status of chemoprevention.

METHODS

Articles were identified by searches of PubMed and the Internet and reviewed. All articles and other referenced materials were retrieved using the keywords "colon cancer", "adenoma", "chemoprevention", "non steroidal anti-inflammatory drugs", "aspirin", "HMG-CoA reductase inhibitors", "bile acids", "Difluoromethylornithine", "hormone replacement therapy", "mesalamine", "curcumin", and "calcium". Papers were published between 1960 and 2008, with older references selected for historical significance. Only papers published in English were reviewed.

RESULTS

Recent preclinical as well as clinical trials have provided data on the potential benefit of a number of drugs and nutritional elements in the field of CRC prevention. Currently, only celecoxib is FDA approved for chemoprevention of CRC and only for high-risk patients with Familial Adenomatous Polyposis (FAP). This is mainly due to cardiovascular toxicity reported in individuals with a personal history of sporadic adenomas. Aspirin and sulindac have also repeatedly demonstrated efficacy in this setting. However, due to increased risk of associated GI toxicity their benefit will have to be weighed against their risk. Combination therapy, using lower doses of each medication, is drawing a great deal of attention and many studies utilizing a variety of chemopreventive agents are presently under study. Promising results have recently been published using sulindac and DFMO.

CONCLUSION

Many agents have shown positive results in the field of chemoprevention however, the ideal chemopreventive agent remains to be discovered with great emphasis on need not to harm. Combining different agents may maximize effectiveness while limiting drug toxicity.

Ursodeoxycholic acid suppresses Cox-2 expression in colon cancer: roles of Ras, p38, and CCAAT/enhancer-binding protein

In the azoxymethane (AOM) model of experimental rodent colon cancer, cholic acid and its colonic metabolite deoxycholic acid (DCA) strongly promote tumorigenesis. In contrast, we showed that ursodeoxycholic acid (UDCA), a low abundance bile acid, inhibited AOM tumorigenesis. Dietary UDCA also blocked the development of tumors with activated Ras and suppressed cyclooxygenase-2 (Cox-2) upregulation in AOM tumors. In this study, we compared the effect of dietary supplementation with tumor-promoting cholic acid to chemopreventive UDCA on Cox-2 expression in AOM tumors. Cholic acid enhanced Cox-2 upregulation in AOM tumors, whereas UDCA inhibited this increase and concomitantly decreased CCAAT/enhancer binding protein beta (C/EBPbeta), a transcriptional regulator of Cox-2. In HCA-7 colon cancer cells, DCA activated Ras and increased C/EBPbeta and Cox-2 by a mechanism requiring the mitogen-activated protein kinase p38. UDCA inhibited DCA-induced p38 activation and decreased C/EBPbeta and Cox-2 upregulation. Using transient transfections, UDCA inhibited Cox-2 promoter and C/EBP reporter activation by DCA. Transfection with dominant-negative (17)N-Ras abolished DCA-induced p38 activation and C/EBPbeta and Cox-2 upregulation. Taken together, these studies have identified a transcriptional pathway regulating Cox-2 expression involving Ras, p38, and C/EBPbeta that is inhibited by UDCA. These signal transducers are novel targets of UDCA's chemopreventive actions.

Intestinal bile acid physiology and pathophysiology

Bile acids (BAs) have a long established role in fat digestion in the intestine by acting as tensioactives, due to their amphipathic characteristics. BAs are reabsorbed very efficiently by the intestinal epithelium and recycled back to the liver via transport mechanisms that have been largely elucidated. The transport and synthesis of BAs are tightly regulated in part by specific plasma membrane receptors and nuclear receptors. In addition to their primary effect, BAs have been claimed to play a role in gastrointestinal cancer, intestinal inflammation and intestinal ionic transport. BAs are not equivalent in any of these biological activities, and structural requirements have been generally identified. In particular, some BAs may be useful for cancer chemoprevention and perhaps in inflammatory bowel disease, although further research is necessary in this field. This review covers the most recent developments in these aspects of BA intestinal biology.

Chemoprevention of colorectal neoplasia: the potential for personalized medicine

CRC development is a multi-step process that spans 10 to 15 years, thereby providing an opportunity for early detection and even prevention. The poor survival rate of advanced CRC has prompted the emphasis on prevention of this disease. CRC screening and removal of adenomas is an effective intervention, and is the cornerstone of prevention. However, screening efforts have had limited impact due to less than optimal compliance with guidelines. Chemoprevention involves the long-term use of a variety of oral agents that can delay, prevent or even reverse the development of adenomas in the large bowel, thus interfering with the multi-step progessing from adenoma to carcinoma. This effect is of particular importance to individuals with a hereditary prediposition to colorectal neoplasia and to those who are especially susceptile to the environmental causes of CRC. NSAIDs have drawn the most attention as chemoprevention agents. Sulindac and celecoxib are effective in promoting poly regression in high risk individuals with Familial Adenomatous Polyposis (FAP). In the more common sporadic setting the APROVe (refecoxib), APC and PreSAP (Celecoxib) trials have shown a significant reduction in adenoma recurrence but important concerns exist regarding cardiovascular toxicity associated with selective COX-2 inhibitors. These landmark studies are very important, as they provide a proof of concept that we can prevent high risk adenomas that can lead to CRC development. The ideal chemopreventive agent remains to be discovered with great emphasis on need not to harm. Possibly, combinations of agents will maximize effectiveness while limiting drug toxicity. Finally, personalized approaches will include the ability to predict risk and toxicity.

Ursodeoxycholic acid modulates histone acetylation and induces differentiation and senescence

Agents that can modulate colonic environment and control dysregulated signaling are being evaluated for their chemopreventive potential in colon cancer. Ursodeoxycholate (UDCA) has shown chemopreventive potential in preclinical and animal models of colon cancer, but the mechanism behind it remains unknown. Here biological effects of UDCA were examined to understand mechanism behind its chemoprevention in colon cancer. Our data suggests that UDCA can suppress growth in a wide variety of cancer cell lines and can induce low level of apoptosis in colon cancer cells. We also found that UDCA treatment induces alteration in morphology, increased cell size, upregulation of cytokeratin 8, 18 and 19 and E-cadherin, cytokeratin remodeling and accumulation of lipid droplets, suggesting that UDCA induces differentiation in colon carcinoma cells. Our results also suggest significant differences in UDCA and sodium butyrate induced functional differentiation. We also report for the first time that UDCA can induce senescence in colon cancer cells as assessed by flattened, spread out and vacuolated morphology as well as by senescence marker beta-galactosidase staining. We also found that UDCA inhibits the telomerase activity. Surprisingly, we found that UDCA is not a histone deacytylase inhibitor but instead induces hypoacetylation of histones unlike hyperacetylation induced by sodium butyrate. Our results also suggest that, although UDCA induced senescence is p53, p21 and Rb independent, HDAC6 appears to be important in UDCA induced senescence. In summary, our data shows that UDCA modulates chromatin by inducing histone hypoacetylation and induces differentiation and senescence in colon cancer cells.

Dietary anthocyanin-rich tart cherry extract inhibits intestinal tumorigenesis in APC(Min) mice fed suboptimal levels of sulindac

A promising approach for cancer chemoprevention might be a combination therapy utilizing dietary phytochemicals and anticarcinogenic pharmaceuticals at a suboptimal dosage to minimize any potential adverse side effects. To test this hypothesis, various dosages of anthocyanin-rich tart cherry extract were fed in combination with suboptimal levels of the nonsteroidal anti-inflammatory drug sulindac to APCMin mice for 19 weeks. By the end of the feeding period, fewer mice that were fed the anthocyanin-rich extract in combination with sulindac lost more than 10% of body weight than mice fed sulindac alone. Mice that were fed anthocyanin-rich extract (at any dose) in combination with sulindac had fewer tumors and a smaller total tumor burden (total tumor area per mouse) in the small intestine when compared to mice fed sulindac alone. These results suggest that a dietary combination of tart cherry anthocyanins and sulindac is more protective against colon cancer than sulindac alone.

Chemoprevention of colorectal cancer: two steps forward, one step back?

Colorectal cancer (CRC) is a leading cause of cancer-related morbidity and mortality in the Western world. The poor survival rate has prompted the emphasis on prevention of this disease. Removal of adenomas at colonoscopy is highly effective and is the cornerstone of screening/surveillance strategies. However, screening efforts have had limited impact owing to low compliance with guidelines. Chemoprevention aims to prevent the development or recurrence of precancerous lesions and cancers with the use of compounds that block the carcinogenic process. A major advantage was the establishment and understanding of the multistage process of CRC carcinogenesis. Progress has been remarkable because of the availability of reliable animal models and clinical studies using colonic adenomas as a reliable and economic target for testing chemopreventive agents. Nonsteroidal anti-inflammatory drugs have drawn the most attention. Sulindac and celecoxib were shown to be effective in promoting polyp regression in high-risk individuals with familial adenomatous polyposis. In the more common sporadic setting, the Adenomatous Polyp PRevention On Vioxx® (rofecoxib), Adenoma Prevention with Celecoxib and Prevention of Sporadic Adenomatous Polyps (celecoxib) trials have demonstrated a significant reduction in adenoma recurrence, but important concerns were raised regarding cardiovascular toxicity associated with selective cyclo-oxygenase-2 inhibitors. These landmark studies are very important, as they are a proof-of-concept that we can prevent CRC. More clinical studies are required to better select high-risk patients with safer regimens. Potential advantage versus risk for a given chemopreventive agent will have to be assessed on an individual basis. Currently, the only approved agent for chemoprevention is celecoxib in high-risk individuals with familial adenomatous polyposis.

Docosahexaenoic acid in combination with celecoxib modulates HSP70 and p53 proteins in prostate cancer cells

The role of cyclooxygenase-2 (COX-2) and the mechanism by which it influences the development and behavior of prostate cancer is unclear. Selective COX-2 inhibitors may be effective against prostate cancer via COX-2-independent mechanisms. But administration of high doses of COX-2 inhibitors over longer period of time may not be devoid of side effects. There is increasing interest in using COX-2 inhibitors in combination with other chemopreventive agents to overcome the issue of toxicity. However, the molecular mechanisms underlying their combined actions are not well understood. Therefore, the present study was designed to determine the effects of low doses of docosahexaenoic acid (DHA) in combination with celecoxib on the molecular targets at the proteins level in rat prostate cancer cells. Two-dimensional gel electrophoresis, in combination with mass spectrometry analysis, was used for protein identification. Western blot analysis confirmed the proteins identified. Paraffin-embedded tissue sections from the rat prostate tumor were used to detect base level expression of heat shock protein 70 (HSP70) and p53. The rate of cancer cell growth was inhibited more effectively (p < 0.01) by DHA in combination with celecoxib at lower doses (2.5 microM each). A total number of twelve proteins were differentially expressed by the combined action of DHA and celecoxib at low doses. It was interesting to note that these agents activated both HSP70 and p53 proteins. Activation of HSP70 by the combined actions of DHA and celecoxib in the presence of wild-type p53 reveals a unique COX-2 independent mode of action against prostate cancer.

Defective acute apoptotic response to genotoxic carcinogen in small intestine of APC(Min/+) mice is restored by sulindac

The effect of APC loss on azoxymethane (AOM)-induced apoptosis and cell proliferation, as well as their regulation by sulindac was examined in colon and small intestine in APC(Min/+) mice. APC(Min/+) mice showed increased epithelial proliferation in all regions, with significant impairment of apoptosis in small intestine, but not in colon. Sulindac administration restored defective apoptosis to normal. As the apoptotic defect occurred at the major site of intestinal tumor formation in APC(Min/+) mice and as it was restored to normal by a proven chemopreventive agent, this defect in apoptosis might be a key biological consequence of APC dysfunction contributing to tumor formation.

Prevention of colitis-associated carcinogenesis in a mouse model by diet supplementation with ursodeoxycholic acid

Bile acids in the intestinal lumen contribute to the homeostatic regulation of proliferation and death of the colonic epithelial cells: Deoxycholic acid (DCA) appears to enhance and ursodeoxycholic acid (UDCA) to attenuate the process of chemically induced carcinogenesis. We studied the effects of UDCA on colitis-related colorectal carcinogenesis. Three groups of 25 mice were given 0.7% dextran sulphate in drinking water for 7 days and pure water for 10 days and were fed a standard diet containing double iron concentration. In 2 groups, the diet was supplemented with 0.2% cholic acid (CA), the precursor of DCA, or with 0.4% UDCA. After 15 cycles, the histology, the expression of MUC2, beta-catenin, p27 and p16 and the fecal water concentration of DCA and UDCA were investigated. All animals showed colitis with similar severity and histologic as well as immunophenotypic alterations, resembling those of human colitis. Among the animals fed the nonsupplemented diet, 46% developed colorectal adenocarcinomas and 54% anal-rectal squamous cell carcinomas. The prevalence of dysplasia and carcinomas did not change significantly in the animals given CA. Among the mice fed with UDCA, none developed adenocarcinomas and 20% squamous carcinomas. Dysplastic lesions were found in 88%, 67% and 40% of each group, respectively. The prevalence of dysplasia as well as of carcinoma showed an inverse relationship to the UDCA concentration in the fecal water. These data indicate that UDCA suppresses colitis-associated carcinogenesis. This model is suitable for investigation of the mechanism of the anticarcinogenic effect of UDCA in vivo.

Ursodeoxycholic acid inhibits translocation of protein kinase C in human colonic cancer cell lines

Deoxycholic acid (DCA) has been implicated in colonic carcinogenesis through effects mediated by protein kinase C (PKC) activation. By contrast, ursodeoxycholic acid (UDCA) is reported to reduce colon cancer incidence in ulcerative colitis. The aim of this study was to investigate whether UDCA modulated DCA-induced PKC isoenzyme translocation to its site of activity. HCT116 cells were treated with DCA, UDCA alone or pre-treated with UDCA followed by DCA. Analysis of translocation of endogenous and enhanced green fluorescent protein (EGFP) constructs of PKC isoenzymes was performed. Both DCA and phorbol myristate acetate (PMA) but not UDCA caused translocation of endogenous PKC alpha, epsilon and delta and transfected PKC beta1-, epsilon- and delta-EGFP from cytosol to plasma membrane, reflecting isoenzyme activation. Furthermore, UDCA inhibited DCA-induced translocation of PKC isoenzymes. Inhibition of DCA-induced PKC translocation may be a mechanism for UDCA-mediated chemoprevention of colon carcinogenesis.

Ursodeoxycholic acid inhibits interleukin beta 1 and deoxycholic acid-induced activation of NF-κB and AP-1 in human colon cancer cells

Deoxycholic acid (DCA) has been implicated in colorectal carcinogenesis in humans with effects on proliferation and apoptosis, mediated at least in part by activation of transcription factors nuclear factor kappa B (NF-kappaB), activator protein 1 (AP-1) and protein kinase C (PKC) enzymes. Ursodeoxycholic acid (UDCA) is reported to reduce the frequency of colonic carcinogenesis in ulcerative colitis patients. Hence, we postulated that it might differ from DCA in its regulation of these transcription factors. The aim of the study was to determine effects of DCA and UDCA on NF-kappaB and AP-1 activation and explore its relationship to PKC. Human colonic tumour cell lines HCT116 were treated with DCA, UDCA, alone or pretreated with UDCA followed by DCA or IL-1beta. In other experiments, cells were pretreated with PKC inhibitors and then stimulated with DCA and IL-1beta or PMA. Gel shift assays were performed on nuclear extracts of the cells for NF-kappaB and AP-1 analysis. Western blot analyses and immunofluorescence were performed for Rel A (p65) and IkappaB-alpha levels on the treated cells. DCA increased NF-kappaB and AP-1 DNA binding. UDCA did not increase DNA binding of NF-kappaB and AP-1 and UDCA pretreatment inhibited DCA-induced NF-kappaB and AP-1 DNA binding. PKC inhibitors blocked DCA-induced NF-kappaB and AP-1 activation. These results were validated by Western blot analysis for RelA and IkappaB-alpha. In conclusion, UDCA did not induce NF-kappaB and AP-1 DNA binding but also blocked DCA-induced NF-kappaB and AP-1 activation. These findings suggest a possible mechanistic role for UDCA in blocking pathways thought to be involved in colon carcinogenesis.

Phase III trial of ursodeoxycholic acid to prevent colorectal adenoma recurrence

BACKGROUND

Ursodeoxycholic acid (UDCA) treatment is associated with a reduced incidence of colonic neoplasia in preclinical models and in patients with conditions associated with an increased risk for colon cancer. We conducted a phase III, double-blind placebo-controlled trial of UDCA to evaluate its ability to prevent colorectal adenoma recurrence.

METHODS

We randomly assigned 1285 individuals who had undergone removal of a colorectal adenoma within the past 6 months to daily treatment with UDCA (8-10 mg/kg of body weight; 661 participants) or with placebo (624 participants) for 3 years or until follow-up colonoscopy. Recurrence rates (number of recurrent adenomas per unit time) were compared by use of a Huber-White variance estimator. Proportions of participants with one or more recurrent adenomas were compared with a Pearson chi-square statistic; adjusted odds ratios (ORs) were obtained by logistic regression. All statistical tests were two-sided.

RESULTS

We observed a non-statistically significant 12% reduction in the adenoma recurrence rate associated with UDCA treatment, compared with placebo treatment. However, UDCA treatment was associated with a statistically significant reduction (P = .03) in the recurrence of adenomas with high-grade dysplasia (adjusted OR = 0.61, 95% confidence interval = 0.39 to 0.96). We observed no statistically significant differences between UDCA and placebo groups in recurrence with regard to adenoma size, villous histology, or location.

CONCLUSIONS

UDCA treatment was associated with a non-statistically significant reduction in total colorectal adenoma recurrence but with a statistically significant 39% reduction in recurrence of adenomas with high-grade dysplasia. Because severely dysplastic lesions have a high risk of progression to invasive colorectal carcinoma, this finding indicates that future chemoprevention trials of UDCA in individuals with such lesions should be considered.

Increased Cyclooxygenase-2 Expression in Duodenal Compared with Colonic Tissues in Familial Adenomatous Polyposis and Relationship to the −765G → C COX-2 Polymorphism

BACKGROUND

Colorectal cancers arising in patients with familial adenomatous polyposis (FAP) can be largely prevented by polyp surveillance and prophylactic colectomy. As a result, duodenal adenocarcinoma has become a leading cause of death in patients with FAP. Cyclooxygenase 2 (COX-2) inhibition is effective against colorectal polyposis in FAP, but is less effective in treating duodenal polyps. We compared the expression of COX-2 in duodenal and colorectal adenomas from patients with FAP and from patients with sporadic neoplasms and correlated expression to a COX-2 promoter polymorphism (-765G/-->C) that is reported to influence COX-2 expression.

METHODS

The study population included 36 FAP patients with colonic adenomas, 22 FAP patients with duodenal adenomas, 22 patients with sporadic duodenal adenomas, and 17 patients with sporadic duodenal adenocarcinoma. Neoplastic and corresponding normal tissue COX-2 expressions were determined using immunohistochemistry on tissue microarrays. The prevalence and ethnic distribution of a polymorphism in the COX-2 promoter that influences COX-2 expression (-765G --> C) were determined in DNA from 274 individuals by real-time quantitative PCR.

RESULTS

Among patients with FAP, histologically normal duodenal mucosa showed higher COX-2 expression than normal colonic mucosa (P < 0.02), and duodenal adenomas had higher COX-2 expression than colonic adenomas (P </= 0.01). In addition, the normal duodenum of patients with FAP showed higher COX-2 expression than the normal duodenal mucosa of patients with sporadic adenomas (P < 0.05). COX-2 expression was significantly higher in the normal-appearing (P < 0.01) mucosa of patients with FAP carrying the -765GG genotype compared with those carrying the -765GC or -765CC genotypes. The -765C genotype was more common in African Americans than in Caucasians (52% versus 33%, P < 0.01).

CONCLUSIONS

High COX-2 expression in the normal and adenomatous duodenal mucosa of patients with FAP may explain the poorer response of these neoplasms to chemoprevention with COX-2 inhibitors.