Chemoprevention of colorectal cancer with ursodeoxycholic acid: pro

Research Progress of Bile Acids in Cancer

Bile acids (BAs) were originally known as detergents to facilitate the digestion and absorption of lipids. And our current knowledge of BAs has been extended to potential carcinogenic or cancer suppressor factors due to constant research. In fact, BAs were regarded as a tumor promoters as early as the 1940s. Differential bile acid signals emitted by various bile acid profiles can produce distinct pathophysiological traits, thereby participating in the occurrence and development of tumors. Nevertheless, in recent years, more and more studies have noticed the value of BAs as therapeutic targets. And several studies have applied BAs as a therapeutic agent for various diseases including cancer. Based on the above evidence, we acknowledge that the role of BAs in cancer has yet to be exploited, although considerable efforts have been made to probe the functions of BAs. In this review, we describe the characteristics of BAs as a double-edged sword in cancer, hoping to provide references for future cancer treatments.

Bile-Acid-Appended Triazolyl Aryl Ketones: Design, Synthesis, In Vitro Anticancer Activity and Pharmacokinetics in Rats

A library of bile-acid-appended triazolyl aryl ketones was synthesized and characterized by detailed spectroscopic techniques such as ¹H and ¹³C NMR, HRMS and HPLC. All the synthesized conjugates were evaluated for their cytotoxicity at 10 µM against MCF-7 (human breast adenocarcinoma) and 4T1 (mouse mammary carcinoma) cells. In vitro cytotoxicity studies on the synthesized conjugates against MCF-7 and 4T1 cells indicated one of the conjugate 6cf to be most active against both cancer cell lines, with IC₅₀ values of 5.71 µM and 8.71 µM, respectively, as compared to the reference drug docetaxel, possessing IC₅₀ values of 9.46 µM and 13.85 µM, respectively. Interestingly, another compound 6af (IC₅₀ = 2.61 µM) was found to possess pronounced anticancer activity as compared to the reference drug docetaxel (IC₅₀ = 9.46 µM) against MCF-7. In addition, the potent compounds (6cf and 6af) were found to be non-toxic to normal human embryonic kidney cell line (HEK 293), as evident from their cell viability of greater than 86%. Compound 6cf induces higher apoptosis in comparison to 6af (46.09% vs. 33.89%) in MCF-7 cells, while similar apoptotic potential was observed for 6cf and 6af in 4T1 cells. The pharmacokinetics of 6cf in Wistar rats showed an MRT of 8.47 h with a half-life of 5.63 h. Clearly, these results suggest 6cf to be a potential candidate for the development of anticancer agents.

Reviewing the Risk of Colorectal Cancer in Inflammatory Bowel Disease After Liver Transplantation for Primary Sclerosing Cholangitis

The presence of concomitant primary sclerosing cholangitis (PSC) with inflammatory bowel disease (IBD) represents a distinct disease phenotype that carries a higher risk of colorectal cancer (CRC) than the average IBD patient. Given that liver transplantation (LT) is the only treatment that offers a survival benefit in PSC patients with hepatic dysfunction, management decisions in IBD patients' post-LT for PSC are frequently encountered. One such consideration is the risk of CRC in this immunosuppressed cohort. With most studies showing an increased risk of CRC post-LT in these IBD patients, a closer look at the associated risk factors of CRC and the adopted surveillance strategies in this subset of patients is warranted. Low-dose ursodeoxycholic acid has shown a potential chemopreventive effect in PSC-IBD patients pre-LT; however, a favorable effect remains to be seen in post-LT group. Also, further studies are necessary to assess the benefit of 5 aminosalicylate therapy. Annual surveillance colonoscopy in the post-LT period is recommended for PSC-IBD patients subset given their high risk for CRC.

Association between Circulating Vitamin D Metabolites and Fecal Bile Acid Concentrations

Although hydrophobic bile acids have been demonstrated to exhibit cytotoxic and carcinogenic effects in the colorectum, ursodeoxycholic acid (UDCA) has been investigated as a potential chemopreventive agent. Vitamin D has been shown to play a role in both bile acid metabolism and in the development of colorectal neoplasia. Using a cross-sectional design, we sought to determine whether baseline circulating concentrations of the vitamin D metabolites 25(OH)D and 1,25(OH)2D were associated with baseline fecal bile acid concentrations in a trial of UDCA for the prevention of colorectal adenoma recurrence. We also prospectively evaluated whether vitamin D metabolite concentrations modified the effect of UDCA on adenoma recurrence. After adjustment for age, sex, BMI, physical activity, and calcium intake, adequate concentrations of 25(OH)D (≥30 ng/mL) were statistically significantly associated with reduced odds for high levels of total [OR, 0.61; 95% confidence interval (CI), 0.38-0.97], and primary (OR, 0.61; 95% CI, 0.38-0.96) bile acids, as well as individually with chenodeoxycholic acid (OR, 0.39; 95% CI, 0.24-0.63) and cholic acid (OR, 0.56; 95% CI, 0.36-0.90). No significant associations were observed for 1,25(OH)2D and high versus low fecal bile acid concentrations. In addition, neither 25(OH)D nor 1,25(OH)2D modified the effect of UDCA on colorectal adenoma recurrence. In conclusion, this is the first study to demonstrate an inverse relationship between circulating levels of 25(OH)D and primary fecal bile acid concentrations. These results support prior data demonstrating that vitamin D plays a key role in bile acid metabolism, and suggest a potential mechanism of action for 25(OH)D in colorectal cancer prevention. Cancer Prev Res; 9(7); 589-97. ©2016 AACR.

Foodomics as part of the host-microbiota-exposome interplay

The functional complexity of human gut microbiota and its relationship with host physiology and environmental modulating factors, offers the opportunity to investigate (i) the host and microbiota role in organism-environment relationship; (ii) the individual functional diversity and response to environmental stimuli (exposome); (iii) the host genome and microbiota metagenomes' modifications by diet-mediated epigenomic controls (nutriepigenomics); and (iv) the genotype-phenotype "trajectories" under physiological and disease constraints. Systems biology-based approaches aim at integrating biological data at cellular, tissue and organ organization levels, using computational modeling to interpret diseases' physiopathological mechanisms (i.e., onset and progression). Proteomics improves the existing gene models by profiling molecular phenotypes at protein abundance level, by analyzing post-translational modifications and protein-protein interactions and providing specific pathway information, hence contributing to functional molecular networks. Transcriptomics and metabolomics may determine host ad microbiota changes induced by food ingredients at molecular level, complementing functional genomics and proteomics data. Since foodomics is an -omic wide methodology may feed back all integrative data to foster the omics-based systems medicine field. Hence, coupled to ecological genomics of gut microbial communities, foodomics may highlight health benefits from nutrients, dissecting diet-induced gut microbiota eubiosis mechanisms and significantly contributing to understand and prevent complex disease phenotypes.

BIOLOGICAL SIGNIFICANCE

Besides transcriptomics and proteomics there is a growing interest in applying metabolic profiling to food science for the development of functional foods. Indeed, one of the biggest challenges of modern nutrition is to propose a healthy diet to populations worldwide, intrinsically respecting the high inter-individual variability, driven by complex host/nutrients/microbiota/environment interactions. Therefore, metabolic profiling can assist at various levels for the development of functional foods, starting from screening for food composition to identification of new biomarkers to trace food intake. This current approach can support diet intervention strategies, epidemiological studies, and controlling of metabolic disorders worldwide spreading, hence ensuring healthy aging. With high-throughput molecular technologies driving foodomics, studying bidirectional interactions of host-microbial co-metabolism, innate immune development, dysfunctional nutrient absorption and processing, complex signaling pathways involved in nutritional metabolism, is now likely. In all cases, as microbiome pipeline efforts continue, it is possible that enhanced standardized protocols can be developed, which may lead to new testable biological and clinical hypotheses. This Review provides a comprehensive update on the current state-of-the-art of the integrated -omics route in food, microbiota and host co-metabolism studies, which may revolutionize the design of new dietary intervention strategies.

Consequences of bile salt biotransformations by intestinal bacteria

Emerging evidence strongly suggest that the human "microbiome" plays an important role in both health and disease. Bile acids function both as detergents molecules promoting nutrient absorption in the intestines and as hormones regulating nutrient metabolism. Bile acids regulate metabolism via activation of specific nuclear receptors (NR) and G-protein coupled receptors (GPCRs). The circulating bile acid pool composition consists of primary bile acids produced from cholesterol in the liver, and secondary bile acids formed by specific gut bacteria. The various biotransformation of bile acids carried out by gut bacteria appear to regulate the structure of the gut microbiome and host physiology. Increased levels of secondary bile acids are associated with specific diseases of the GI system. Elucidating methods to control the gut microbiome and bile acid pool composition in humans may lead to a reduction in some of the major diseases of the liver, gall bladder and colon.

Synthesis, characterization and biological evaluation of bile acid-aromatic/heteroaromatic amides linked via amino acids as anti-cancer agents

A series of bile acid (Cholic acid and Deoxycholic acid) aryl/heteroaryl amides linked via α-amino acid were synthesized and tested against 3 human cancer cell-lines (HT29, MDAMB231, U87MG) and 1 human normal cell line (HEK293T). Some of the conjugates showed promising results to be new anticancer agents with good in vitro results. More specifically, Cholic acid derivatives 6a (1.35 μM), 6c (1.41 μM) and 6m (4.52 μM) possessing phenyl, benzothiazole and 4-methylphenyl groups showed fairly good activity against the breast cancer cell line with respect to Cisplatin (7.21 μM) and comparable with respect to Doxorubicin (1 μM), while 6e (2.49μM), 6i (2.46 μM) and 6m (1.62 μM) showed better activity against glioblastoma cancer cell line with respect to both Cisplatin (2.60 μM) and Doxorubicin (3.78 μM) drugs used as standards. Greater than 65% of the compounds were found to be safer on human normal cell line.

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.

Diet, the gut microbiome, and epigenetics

Increasingly, the gut microbiome is implicated in the etiology of cancer, not only as an infectious agent but also by altering exposure to dietary compounds that influence disease risk. Whereas the composition and metabolism of the gut microbiome is influenced by diet, the gut microbiome can also modify dietary exposures in ways that are beneficial or detrimental to the human host. The colonic bacteria metabolize macronutrients, either as specialists or in consortia of bacteria, in a variety of diverse metabolic pathways. Microbial metabolites of diet can also be epigenetic activators of gene expression that may influence cancer risk in humans. Epigenetics involves heritable changes in gene expression via post-translational and post-transcriptional modifications. Microbial metabolites can influence epigenetics by altering the pool of compounds used for modification or by directly inhibiting enzymes involved in epigenetic pathways. Colonic epithelium is immediately exposed to these metabolites, although some metabolites are also found in systemic circulation. In this review, we discuss the role of the gut microbiome in dietary metabolism and how microbial metabolites may influence gene expression linked to colon cancer risk.

The human gut sterolbiome: bile acid-microbiome endocrine aspects and therapeutics

The human body is now viewed as a complex ecosystem that on a cellular and gene level is mainly prokaryotic. The mammalian liver synthesizes and secretes hydrophilic primary bile acids, some of which enter the colon during the enterohepatic circulation, and are converted into numerous hydrophobic metabolites which are capable of entering the portal circulation, returned to the liver, and in humans, accumulating in the biliary pool. Bile acids are hormones that regulate their own synthesis, transport, in addition to glucose and lipid homeostasis, and energy balance. The gut microbial community through their capacity to produce bile acid metabolites distinct from the liver can be thought of as an “endocrine organ” with potential to alter host physiology, perhaps to their own favor. We propose the term “sterolbiome” to describe the genetic potential of the gut microbiome to produce endocrine molecules from endogenous and exogenous steroids in the mammalian gut. The affinity of secondary bile acid metabolites to host nuclear receptors is described, the potential of secondary bile acids to promote tumors, and the potential of bile acids to serve as therapeutic agents are discussed.

Microbes, microbiota, and colon cancer

Colorectal cancer (CRC) presents a considerable disease burden worldwide. The human colon is also an anatomical location with the largest number of microbes. It is natural, therefore, to anticipate a role for microbes, particularly bacteria, in colorectal carcinogenesis. The increasing accessibility of microbial meta'omics is fueling a surge in our understanding of the role that microbes and the microbiota play in CRC. In this review, we will discuss recent insights into contributions of the microbiota to CRC and explore conceptual frameworks for evaluating the role of microbes in cancer causation. We also highlight new findings on candidate CRC-potentiating species and current knowledge gaps. Finally, we explore the roles of microbial metabolism as it relates to bile acids, xenobiotics, and diet in the etiology and therapeutics of CRC.

Metal Zn(II), Cu(II), Ni (II) complexes of ursodeoxycholic acid as putative anticancer agents

The aim of the study was to evaluate the influence of metal [Zn(II), Cu(II), Ni(II)] complexes with ursodeoxycholic acid (UDCA) on the viability and proliferation of tumour and non-tumour cells. Cell lines established from retrovirus-transformed chicken hepatoma (LSCC-SF-Mc29) and rat sarcoma (LSR-SF-SR) as well as from human cancers of the breast (MCF-7), uterine cervix (HeLa), lung (A549) and liver (HepG2) were used as model systems. Non-tumour human embryo (Lep-3) cells were also included in some of the experiments. The investigations were carried out by the thiazolyl blue tetrazolium bromide (MTT) test, neutral red uptake cytotoxicity assay, crystal violet staining, double staining with acridine orange and propidium iodide and the colony-forming method. The results obtained revealed that: (1) UDCA and its metal complexes in the tested concentrations decreased (to a varying degree) the viability and proliferation of the treated cells in a time- and concentration-dependent manner; (2) chicken hepatoma (LSCC-SF-Mc29) cells were most sensitive to the cytotoxic and antiproliferative action of the compounds tested, followed by rat sarcoma (LSR-SF-SR) cells; (3) Cu‒UDCA and Ni‒UDCA were more effective against animal LSCC-SF-Mc29 and LSR-SF-SR cells, while Zn‒UDCA significantly decreased the viability and proliferation of human tumour cell lines; (4) applied independently, UDCA expressed lower cytotoxic/cytostatic activity as compared to metal complexes; and (5) the sensitivity of the non-tumour embryonic Lep-3 cells to the effects of UDCA and its metal complexes was comparable or even higher than those of the human tumour cells.

Effect of endogenous and exogenous gastrin on PGE2 and EGF expression in dimethylhydrazine-induced colorectal cancer in rats

AIM: To examine the effect of endogenous and exogenous gastrin on the expression of epidermal growth factor (EGF) and prostaglandin E₂ (PGE₂) in dimethylhydrazine-induced colorectal cancer in rats to explore the role of gastrin (GAS), cyclooxygenase (COX)-2, EGF, PGE₂, and EGF receptor (EGFR) in colorectal cancer.

METHODS: One hundred and forty rats were randomly divided into seven groups: DMH+GAS, DMH+PPI, DMH, DMH+GAS+PGL, DMH+PPI+PGL, DMH+PGL, and control group. The concentrations of GAS, EGF and PGE₂ in serum and large intestine tissue homogenate were determined by radioimmunoassay. The expression of COX-2 and EGFR in the large intestine tissue was detected by immunohistochemistry and quantified by optical density analysis.

RESULTS: The concentrations of GAS (pg/mL) in serum and large intestine tissue homogenate were significantly higher in the DMH+GAS (15.59 ± 2.90, 0.38 ± 0.11) and DMH+GAS+PGL (15.31 ± 5.66, 0.35 ± 0.10) groups than in the control group (8.64 ± 2.36, 0.16 ± 0.03) (all P < 0.05), and in DMH+PPI (20.50 ± 3.71, 0.45 ± 0.13) and DMH+PPI+PGL (19.90 ± 5.10, 0.37 ± 0.11) groups than in the DMH (13.12 ± 3.47, 0.19 ± 0.04), DMH+PGL (11.45 ± 5.13, 0.20 ± 0.05) and blank control groups (all P < 0.05). The concentrations of EGF (ng/mL) in serum and large intestine tissue homogenate were significantly higher in the DMH+GAS (4.26 ± 0.92, 0.011 ± 0.005) and DMH+GAS+PGL (4.29 ± 0.50, 0.009 ± 0.005) groups than in the control group (2.91 ± 0.54, 0.002 ± 0.0007) (all P < 0.05), and in DMH+PPI (5.20 ± 1.03, 0.015 ± 0.007) and DMH+PPI+PGL (5.13 ± 0.50, 0.011 ± 0.007) groups than in the DMH (3.76 ± 1.47, 0.004 ± 0.002), DMH+PGL (3.59 ± 1.12, 0.002 ± 0.0018) and control groups (all P < 0.05). The concentrations of PGE₂ (pg/mL) in serum and large intestine tissue homogenate were higher in the DMH+GAS (76.03 ± 60.75, 2.74 ± 0.76) and DMH+PPI (70.29 ± 66.58, 2.42 ± 0.89) groups than in other groups, but the differences were not statistically significant (all P > 0.05). Serum and tissue concentrations of GAS (32.06 pg/mg ± 15.84 pg/mg, 0.73 pg/mg ± 0.31 pg/mg), EGF (4.48 ng/mg ± 1.13 ng/mg, 0.045 ng/mg ± 0.020 ng/mg), PGE₂ (99.05 pg/mg ± 60.80 pg/mg, 4.27 pg/mg ± 1.17 pg/mg) in adenocarcinoma were higher than those in the control group (all P < 0.05). The IA of EGFR (17161.67 ± 9851.33) and COX-2 (21403.33 ± 11377.25) in the adenocarcinoma group was higher than that in the adenoma (5154.00 ± 2744.13, 7291.60 ± 2849.12) and control (3327.11 ± 1880.44, 4822.90 ± 2340.89) groups (all P < 0.05). The positive rates of EGFR (66.7%) and COX-2 (81.5%) expression in the adenocarcinoma group was higher than those in the control group (0%, 30%) (all P < 0.05).

CONCLUSION: Endogenous and exogenous gastrin could induce the expression of EGF and stimulate the secretion of PGE₂ in colorectal cancer. PGL does not inhibit the effect of GAS on EGF. GAS, EGF, PGE₂, EGFR, and COX-2 play an important role in the formation of colorectal cancer. EGFR and COX-2 are involved in the proliferation of colorectal tumors.