Bile acids as endogenous etiologic agents in gastrointestinal cancer

Biliary reflux as a causal factor in hypopharyngeal carcinoma: New clinical evidence and implications

BACKGROUND

Recent preclinical explorations strongly support the tumorigenic potential of bile on laryngopharyngeal mucosa. Herein, the authors describe, in bile-related human hypopharyngeal squamous cell carcinoma (HSCC), NF-κB-related messenger RNA (mRNA) and microRNA (miRNA) oncogenic phenotypes similar to those previously identified in acidic bile-exposed premalignant murine hypopharyngeal mucosa.

METHODS

In this pilot study, the authors included human HSCC specimens paired with their adjacent normal tissue (ANT) derived from 3 representative patients with documented biliary laryngopharyngeal reflux (bile[+]) compared with 5 control patients without signs of bile reflux disease (bile[-]). Immunohistochemical, quantitative polymerase chain reaction, and miRNA analyses were used to detect the levels of activated NF-κB and expression levels of STAT3, EGFR, BCL2, WNT5A, IL-6, IL-1B, ΔNp63, cREL, TNF-α, TP53, NOTCH1, NOTCH2, NOTCH3, miR-21, miR-155, miR-192, miR-34a, miR-375, miR-451a, miR-489, miR-504, and miR-99a.

RESULTS

Bile(+) HSCC demonstrated an intense NF-κB activation accompanied by significant overexpression of RELA(p65), EGFR, STAT3, BCL-2, cREL, ΔNp63, WNT5A, IL-6, and IL1B; upregulation of oncomir miR-21; and downregulation of tumor suppressor miR-375 compared with their respective ANTs. Bile(+) HSCC demonstrated significantly higher mRNA levels of all the analyzed genes, particularly RELA(p65), IL-6, EGFR, and TNF-α compared with bile(-) tumors. The miR-21/miR-375 ratio, which previously has been linked to tumor aggressiveness, was found to be >260-fold and >30-fold higher, respectively, in bile(+) HSCCs compared with their ANTs and bile(-) tumors.

CONCLUSIONS

Although limitations apply to this pilot study due to the small number of patients with HSCC, the novel findings suggest that a history of bile as a component of esophageal reflux disease may represent an independent risk factor for hypopharyngeal carcinogenesis.

APE1 Upregulates MMP-14 via Redox-Sensitive ARF6-Mediated Recycling to Promote Cell Invasion of Esophageal Adenocarcinoma

Esophageal adenocarcinoma (EAC) is an aggressive malignancy with poor clinical outcome. The incidence of EAC has been rising rapidly in the past three decades. Here, we showed that apurinic/apyrimidinic endonuclease (APE1) is overexpressed in EAC cell lines, and patients' samples of dysplasia and EAC. Downregulation of APE1 or inhibition of its redox function significantly repressed invasion. Overexpression of a redox-defective mutant, C65A, abrogated the proinvasive phenotype of APE1. APE1 regulated invasion via upregulation of matrix metalloproteinase 14 (MMP-14), which subsequently activated MMP-2, leading to degradation of the extracellular matrix in a redox-dependent manner. Downregulation of APE1 or inhibition of its redox function decreased the rate of endocytosis and recycling of MMP-14 protein. APE1 interacted with ARF6, a key regulator of MMP-14 recycling, which maintained ARF6 activity in an APE1-redox-dependent manner, promoting its ability to regulate MMP-14 recycling to the cell surface. In summary, these findings identify a novel redox-sensitive APE1-ARF6-MMP-14 signaling axis that mediates cellular invasion in esophageal carcinogenesis. SIGNIFICANCE: This study demonstrates the association between oxidative stress and the development and metastatic behavior of esophageal adenocarcinoma.

Efficacy and safety of a novel topical agent for gallstone dissolution: 2-methoxy-6-methylpyridine

BACKGROUND

Although methyl-tertiary butyl ether (MTBE) is the only clinical topical agent for gallstone dissolution, its use is limited by its side effects mostly arising from a relatively low boiling point (55 °C). In this study, we developed the gallstone-dissolving compound containing an aromatic moiety, named 2-methoxy-6-methylpyridine (MMP) with higher boiling point (156 °C), and compared its effectiveness and toxicities with MTBE.

METHODS

The dissolubility of MTBE and MMP in vitro was determined by placing human gallstones in glass containers with either solvent and, then, measuring their dry weights. Their dissolubility in vivo was determined by comparing the weights of solvent-treated gallstones and control (dimethyl sulfoxide)-treated gallstones, after directly injecting each solvent into the gallbladder in hamster models with cholesterol and pigmented gallstones.

RESULTS

In the in vitro dissolution test, MMP demonstrated statistically higher dissolubility than did MTBE for cholesterol and pigmented gallstones (88.2% vs. 65.7%, 50.8% vs. 29.0%, respectively; P < 0.05). In the in vivo experiments, MMP exhibited 59.0% and 54.3% dissolubility for cholesterol and pigmented gallstones, respectively, which were significantly higher than those of MTBE (50.0% and 32.0%, respectively; P < 0.05). The immunohistochemical stains of gallbladder specimens obtained from the MMP-treated hamsters demonstrated that MMP did not significantly increase the expression of cleaved caspase 9 or significantly decrease the expression of proliferation cell nuclear antigen.

CONCLUSIONS

This study demonstrated that MMP has better potential than does MTBE in dissolving gallstones, especially pigmented gallstones, while resulting in lesser toxicities.

Metagenomic and metabolomic analyses reveal distinct stage-specific phenotypes of the gut microbiota in colorectal cancer

In most cases of sporadic colorectal cancers, tumorigenesis is a multistep process, involving genomic alterations in parallel with morphologic changes. In addition, accumulating evidence suggests that the human gut microbiome is linked to the development of colorectal cancer. Here we performed fecal metagenomic and metabolomic studies on samples from a large cohort of 616 participants who underwent colonoscopy to assess taxonomic and functional characteristics of gut microbiota and metabolites. Microbiome and metabolome shifts were apparent in cases of multiple polypoid adenomas and intramucosal carcinomas, in addition to more advanced lesions. We found two distinct patterns of microbiome elevations. First, the relative abundance of Fusobacterium nucleatum spp. was significantly (P < 0.005) elevated continuously from intramucosal carcinoma to more advanced stages. Second, Atopobium parvulum and Actinomyces odontolyticus, which co-occurred in intramucosal carcinomas, were significantly (P < 0.005) increased only in multiple polypoid adenomas and/or intramucosal carcinomas. Metabolome analyses showed that branched-chain amino acids and phenylalanine were significantly (P < 0.005) increased in intramucosal carcinomas and bile acids, including deoxycholate, were significantly (P < 0.005) elevated in multiple polypoid adenomas and/or intramucosal carcinomas. We identified metagenomic and metabolomic markers to discriminate cases of intramucosal carcinoma from the healthy controls. Our large-cohort multi-omics data indicate that shifts in the microbiome and metabolome occur from the very early stages of the development of colorectal cancer, which is of possible etiological and diagnostic importance.

Diagnostic and therapeutic potential of the gut microbiota in patients with early hepatocellular carcinoma

The gut microbiota is involved in the maintenance of the homeostasis of the human body and its alterations are associated with the development of different pathological conditions. The liver is the organ most exposed to the influence of the gut microbiota, and recently important connections between the intestinal flora and hepatocellular carcinoma (HCC) have been described. In fact, HCC is commonly associated with liver cirrhosis and develops in a microenvironment where inflammation, immunological alterations, and cellular aberrations are dramatically evident. Prevention and diagnosis in the earliest stages are still the most effective weapons in fighting this tumor. Animal models show that the gut microbiota can be involved in the promotion and progression of HCC directly or through different pathogenic mechanisms. Recent data in humans have confirmed these preclinical findings, shedding new light on HCC pathogenesis. Limitations due to the different experimental design, the ethnic and hepatological setting make it difficult to compare the results and draw definitive conclusions, but these studies lay the foundations for a pathogenetic redefinition of HCC. Therefore, it is evident that the characterization of the gut microbiota and its modulation can have an enormous diagnostic, preventive, and therapeutic potential, especially in patients with early stage HCC.

A Pilot Study: Changes of Gut Microbiota in Post-surgery Colorectal Cancer Patients

Colorectal cancer (CRC) is a growing health problem throughout the world. Strong evidences have supported that gut microbiota can influence tumorigenesis; however, little is known about what happens to gut microbiota following surgical resection. Here, we examined the changes of gut microbiota in CRC patients after the surgical resection. Using the PCoA analysis and dissimilarity tests, the microbial taxonomic compositions and diversities of gut microbiota in post-surgery CRC patients (A1) were significantly different from those in pre-surgery CRC patients (A0) and healthy individuals (H). Compared with A0 and H, the Shannon diversity and Simpson diversity were significantly decreased in A1 (P < 0.05). Based on the LEfSe analysis, the relative abundance of phylum Proteobacteria in A1 was significantly increased than that in A0 and H. The genus Klebsiella in A1 had higher proportions than that in A0 (P < 0.05). Individual variation was distinct; however, 90% of CRC patients in A1 had more abundances of Klebsiella than A0. The Klebsiella in A1 was significantly associated with infectious diseases (P < 0.05), revealed by the correlation analysis between differentiated genera and metabolic pathway. The Klebsiella (Proteobacteria, Gammaproteobacteria, Enterobacteriales, Enterobacteriaceae) in A1 was significantly linked with lymphatic invasion (P < 0.05). Furthermore, the PCA of KEGG pathways indicated that gut microbiota with a more scattered distribution in A1 was noticeably different from that in A0 and H. The nodes, the links, and the kinds of phylum in each module in A1 were less than those in A0 and H, indicating that gut microbiota in A1 had a relatively looser ecologcial interaction network. To sum up, this pilot study identified the changes of gut microbiota in post-surgery CRC patients, and highlights future avenues in which the gut microbiota is likely to be of increasing importance in the care of surgical patients.

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.

Calcium and Phosphate Metabolism, Blood Lipids and Intestinal Sterols in Human Intervention Studies Using Different Sources of Phosphate as Supplements-Pooled Results and Literature Search

Phosphates are associated with negative physiological effects. The objectives of this publication were to compare differential effects of supplementation with calcium phosphate or phosphate alone in healthy humans. Four adult human studies were conducted with pentacalcium hydroxy-trisphosphate supplementation (CaP; 90 subjects) and their data were pooled for assessment. For literature search; PubMed and ISI Web of Knowledge were used and 21 items were assigned to three main topics. The pooled study results show that following CaP supplementation, faecal calcium and phosphorus and urinary calcium were increased, blood lipids were positively modulated, and faecal bile acids were increased, as compared with placebo. The literature search reveals that following calcium phosphate supplementation, urinary calcium was increased. Following solely phosphate supplementation, urinary phosphorus was increased and urinary calcium was decreased. Postprandial calcium concentrations were increased following calcium phosphate supplementation. Postprandial phosphate concentrations were increased following solely phosphate supplementation. Calcium phosphate supplementation resulted in rather positively modulated blood lipids and gut-related parameters. The presented results show the relevance to distinguish between calcium phosphate and solely phosphate supplementations, and the importance of a balanced calcium and phosphorus intake.

Exposure of Barrett's and esophageal adenocarcinoma cells to bile acids activates EGFR-STAT3 signaling axis via induction of APE1

The development of Barret’s esophagus (BE) and its progression to esophageal adenocarcinoma (EAC) is highly linked to exposure to acidic bile salts due to chronic gastroesophageal reflux disease (GERD). In this study, we investigated the role of Apurinic/apyrimidinic endonuclease 1 /redox effector factor-1 (APE-1/REF-1) in STAT3 activation in response to EAC. Our results indicate that APE1 is constitutively overexpressed in EAC whereas its expression is transiently induced in response to acidic bile salts in non-neoplastic BE. Using overexpression or shRNA knockdown of APE1, we found that APE1 is required for phosphorylation, nuclear localization, and transcription activation of STAT3. By using an APE1 redox-specific mutant (C65A) and APE1 redox inhibitor (E3330), we demonstrate that APE1 activates STAT3 in a redox-dependent manner. By using pharmacologic inhibitors and genetic knockdown systems, we found that EGFR is a required link between APE1 and STAT3. EGFR phosphorylation (Y1068) was directly associated with APE1 levels and redox function. Co-immunoprecipitation and proximity ligation assays indicated that APE-1 coexists and interacts with the EGFR-STAT3 protein complex. Consistent with these findings, we demonstrated a significant induction in mRNA expression levels of STAT3 target genes (IL-6, IL-17A, BCL-xL, Survivin and c-Myc) in BE and EAC cells, following acidic bile salts treatment. ChIP assays indicated that acidic bile salts treatment enhances binding of STAT3 to the promoter of its target genes, Survivin and BCL-xL. Inhibition of APE1/REF-1 redox activity using E3330 abrogated STAT3 DNA binding and transcriptional activity. The induction of APE-1 - STAT3 axis in acidic bile salts conditions provided a survival advantage and promoted cellular proliferation. In summary, our study provides multiple pieces of evidence supporting a critical role for APE1 induction in activating the EGFR-STAT3 signaling axis in response to acidic bile salts, the main risk factors for Barrett’s carcinogenesis.

Deoxycholic acid activates epidermal growth factor receptor and promotes intestinal carcinogenesis by ADAM17-dependent ligand release

High fat diet is implicated in the elevated deoxycholic acid (DCA) in the intestine and correlated with increased colon cancer risk. However, the potential mechanisms of intestinal carcinogenesis by DCA remain unclarified. Here, we investigated the carcinogenic effects and mechanisms of DCA using the intestinal tumour cells and Apc^min/+ mice model. We found that DCA could activate epidermal growth factor receptor (EGFR) and promote the release of EGFR ligand amphiregulin (AREG), but not HB‐EGF or TGF‐α in intestinal tumour cells. Moreover, ADAM‐17 was required in DCA‐induced promotion of shedding of AREG and activation of EGFR/Akt signalling pathway. DCA significantly increased the multiplicity of intestinal tumours and accelerated adenoma‐carcinoma sequence in Apc^min/+ mice. ADAM‐17/EGFR signalling axis was also activated in intestinal tumours of DCA‐treated Apc^min/+ mice, whereas no significant change occurred in tumour adjacent tissues after DCA exposure. Conclusively, DCA activated EGFR and promoted intestinal carcinogenesis by ADAM17‐dependent ligand release.

Metabolic reprogramming for cancer cells and their microenvironment: Beyond the Warburg Effect

While metabolic reprogramming of cancer cells has long been considered from the standpoint of how and why cancer cells preferentially utilize glucose via aerobic glycolysis, the so-called Warburg Effect, the progress in the following areas during the past several years has substantially advanced our understanding of the rewired metabolic network in cancer cells that is intertwined with oncogenic signaling. First, in addition to the major nutrient substrates glucose and glutamine, cancer cells have been discovered to utilize a variety of unconventional nutrient sources for survival. Second, the deregulated biomass synthesis is intertwined with cell cycle progression to coordinate the accelerated progression of cancer cells. Third, the reciprocal regulation of cancer cell's metabolic alterations and the microenvironment, involving extensive host immune cells and microbiota, have come into view as critical mechanisms to regulate cancer progression. These and other advances are shaping the current and future paradigm of cancer metabolism.

In Vitro Modeling of Bile Acid Processing by the Human Fecal Microbiota

Bile acids, the products of concerted host and gut bacterial metabolism, have important signaling functions within the mammalian metabolic system and a key role in digestion. Given the complexity of the mega-variate bacterial community residing in the gastrointestinal tract, studying associations between individual bacterial genera and bile acid processing remains a challenge. Here, we present a novel in vitro approach to determine the bacterial genera associated with the metabolism of different primary bile acids and their potential to contribute to inter-individual variation in this processing. Anaerobic, pH-controlled batch cultures were inoculated with human fecal microbiota and treated with individual conjugated primary bile acids (500 μg/ml) to serve as the sole substrate for 24 h. Samples were collected throughout the experiment (0, 5, 10, and 24 h) and the bacterial composition was determined by 16S rRNA gene sequencing and the bile acid signatures were characterized using a targeted ultra-performance liquid chromatography-mass spectrometry (UPLC-MS) approach. Data fusion techniques were used to identify statistical bacterial-metabolic linkages. An increase in gut bacteria associated bile acids was observed over 24 h with variation in the rate of bile acid metabolism across the volunteers (n = 7). Correlation analysis identified a significant association between the Gemmiger genus and the deconjugation of glycine conjugated bile acids while the deconjugation of taurocholic acid was associated with bacteria from the Eubacterium and Ruminococcus genera. A positive correlation between Dorea and deoxycholic acid production suggest a potential role for this genus in cholic acid dehydroxylation. A slower deconjugation of taurocholic acid was observed in individuals with a greater abundance of Parasutterella and Akkermansia. This work demonstrates the utility of integrating compositional (metataxonomics) and functional (metabonomics) systems biology approaches, coupled to in vitro model systems, to study the biochemical capabilities of bacteria within complex ecosystems. Characterizing the dynamic interactions between the gut microbiota and the bile acid pool enables a greater understanding of how variation in the gut microbiota influences host bile acid signatures, their associated functions and their implications for health.

Current State of Knowledge on Implications of Gut Microbiome for Surgical Conditions

The role of the microbiome in human health has become a central tenant of current medical research, infiltrating a diverse disciplinary base whereby microbiology, computer science, ecology, gastroenterology, immunology, neurophysiology and psychology, metabolism, and cardiovascular medicine all intersect. Traditionally, commensal gut microbiota have been assumed to play a significant role only in the metabolic processing of dietary nutrients and host metabolites, the fortification of gut epithelial barrier function, and the development of mucosal immunity. However, over the last 20 years, new technologies and renewed interest have uncovered a considerably broader influence of the microbiota on health maintenance and disease development, many of which are of particular relevance for surgeons. This article provides a broad overview of the current state of knowledge and a review of the technology that helped in their formation.

A Comprehensive Genome Survey Provides Novel Insights into Bile Salt Hydrolase (BSH) in Lactobacillaceae

Bile salt hydrolase (BSH) is a well-known enzyme that has been commonly characterized in probiotic bacteria, as it has cholesterol-lowering effects. However, its molecular investigations are scarce. Here, we build a local database of BSH sequences from Lactobacillaceae (BSH⁻SDL), and phylogenetic analysis and homology searches were employed to elucidate their comparability and distinctiveness among species. Evolutionary study demonstrates that BSH sequences in BSH⁻SDL are divided into five groups, named BSH A, B, C, D and E here, which can be the genetic basis for BSH classification and nomenclature. Sequence analysis suggests the differences between BSH-active and BSH-inactive proteins clearly, especially on site 82. In addition, a total of 551 BSHs from 107 species are identified from 451 genomes of 158 Lactobacillaceae species. Interestingly, those bacteria carrying various copies of BSH A or B can be predicted to be potential cholesterol-lowering probiotics, based on the results of phylogenetic analysis and the subtypes that those previously reported BSH-active probiotics possess. In summary, this study elaborates the molecular basis of BSH in Lactobacillaceae systematically, and provides a novel methodology as well as a consistent standard for the identification of the BSH subtype. We believe that high-throughput screening can be efficiently applied to the selection of promising candidate BSH-active probiotics, which will advance the development of healthcare products in cholesterol metabolism.

Patterns of chemical diversity in the marine ascidian Phallusia spp.: anti-tumor activity and metabolic pathway inhibiting steroid biosynthesis

The complex nature of marine biodiversity is partially responsible for the lack of studies in Indian ascidian species, which often target a small number of novel biomolecules. We performed untargeted metabolomics using gas chromatography-mass spectrometry (GC-MS) in two invasive ascidian species to investigate the inter-specific chemical diversity of Phallusia nigra and P. arabica in search of drug-like properties and metabolic pathways. The chemical profiling of individual ascidian species was obtained using GC-MS, and the metabolites were determined by searching in NIST library and literature data. The principal component analysis of GC-MS mass spectral variables showed a clear discrimination of these two ascidian species based on the chemical composition and taxonomy. The metabolites, lipids, macrolides, and steroids contributed strongly to the discrimination of these two species. Results of this study confirmed that GC-MS-based chemical profiling could be utilized as a tool for chemotaxonomic classification of ascidian species. The extract of P. nigra showed promising anti-tumor activity against HT29 colon cancer 35 µM and MCF7-breast cancer (34.76 µM) cells compared to P. arabica. Of the more than 70 metabolites measured, 18 metabolites that mapped various pathways linked to three metabolic pathways being impacted and altered in steroid biosynthesis, primary bile acid biosynthesis, and steroid hormone biosynthesis were observed to have changed significantly (p > 0.004, FDR < 0.01). Also, higher expression of this pathway was associated with more significant cytotoxicity in breast and colon carcinoma cells.

Synbiotics Bifidobacterium infantis and milk oligosaccharides are effective in reversing cancer-prone nonalcoholic steatohepatitis using western diet-fed FXR knockout mouse models

Milk oligosaccharides (MO) selectively increase the growth of Bifidobacterium infantis (B. infantis). This study examines the effects of bovine MO and B. infantis in preventing nonalcoholic steatohepatitis (NASH) in Western diet (WD)-fed bile acid (BA) receptor FXR (farnesoid x receptor) knockout (KO) mice. WD-fed FXR KO mice have cancer-prone NASH and reduced B. infantis. MO and/or B. infantis supplementation improved their insulin sensitivity and reduced hepatic inflammation. Additionally, B. infantis, but not MO, decreased hepatic triglyceride and cholesterol. A combination of both further reduced hepatic cholesterol, the precursor of BAs. All three treatments modulated serum and hepatic BA profile. Moreover, B. infantis and MO decreased hepatic CYP7A1 and induced Sult2a1, Sult2a2, and Sult2a3 suggesting reduced BA synthesis and increased detoxification. Furthermore, B. infantis and MO increased ileal BA membrane receptor TGR5-regulated signaling. Together, via BA-regulated signaling, synbiotics B. infantis and MO have their unique and combined effects in reversing NASH.

Bile acid-microbiota crosstalk in gastrointestinal inflammation and carcinogenesis

Emerging evidence points to a strong association between the gut microbiota and the risk, development and progression of gastrointestinal cancers such as colorectal cancer (CRC) and hepatocellular carcinoma (HCC). Bile acids, produced in the liver, are metabolized by enzymes derived from intestinal bacteria and are critically important for maintaining a healthy gut microbiota, balanced lipid and carbohydrate metabolism, insulin sensitivity and innate immunity. Given the complexity of bile acid signalling and the direct biochemical interactions between the gut microbiota and the host, a systems biology perspective is required to understand the liver-bile acid-microbiota axis and its role in gastrointestinal carcinogenesis to reverse the microbiota-mediated alterations in bile acid metabolism that occur in disease states. An examination of recent research progress in this area is urgently needed. In this Review, we discuss the mechanistic links between bile acids and gastrointestinal carcinogenesis in CRC and HCC, which involve two major bile acid-sensing receptors, farnesoid X receptor (FXR) and G protein-coupled bile acid receptor 1 (TGR5). We also highlight the strategies and cutting-edge technologies to target gut-microbiota-dependent alterations in bile acid metabolism in the context of cancer therapy.

Bile acids in glucose metabolism in health and disease

Bile acids (BAs) are cholesterol-derived metabolites that facilitate the intestinal absorption and transport of dietary lipids. Recently, BAs also emerged as pivotal signaling molecules controlling glucose, lipid, and energy metabolism by binding to the nuclear hormone farnesoid X receptor (FXR) and Takeda G protein receptor 5 (TGR5) in multiple organs, leading to regulation of intestinal incretin secretion, hepatic gluconeogenesis, glycogen synthesis, energy expenditure, inflammation, and gut microbiome configuration. Alterations in BA metabolism and signaling are associated with obesity and type 2 diabetes mellitus (T2DM), whereas treatment of T2DM patients with BA sequestrants, or bariatric surgery in morbidly obese patients, results in a significant improvement in glycemic response that is associated with changes in the BA profile and signaling. Herein, we review the roles of BAs in glucose metabolism in health and disease; highlight the limitations, unknowns, and challenges in understanding the impact of BAs on the glycemic response; and discuss how this knowledge may be harnessed to develop innovative therapeutic approaches for the treatment of hyperglycemia and diabetes.

Increased Risk for Colon Polyps in Patients with Reflux Disease

BACKGROUND

Previous studies have found an increased risk for colonic neoplasm in patients with Barrett's esophagus. It is unknown whether such risk applies similarly to other types of gastroesophageal reflux disease (GERD).

AIMS

To test whether GERD represents a risk factor for the occurrence of colon polyps.

METHODS

The Miraca Life Sciences Database is a large national electronic repository of histopathologic records of patients distributed throughout the entire USA. A case-control study evaluated whether presence of (1) Barrett's metaplasia, (2) erosive esophagitis on endoscopy or histologic signs of reflux esophagitis, (3) clinical diagnosis of GERD, (4) any type of GERD affected the occurrence hyperplastic polyps (HP), sessile serrated adenomas/polyps (SSA/P), or tubular adenomas (TA) among 228,506 subjects undergoing bidirectional endoscopy. Multivariate logistic regression analyses were used to calculate odds ratios and their 95% confidence intervals for the risk of HP, TA or SSA/P associated with various types of GERD and adjusted for age, sex, and presence of H. pylori.

RESULTS

The analysis revealed positive associations between GERD and all types of colon polyps. These associations applied similarly to HP (1.47, 1.44-1.50), TA (1.30, 1.27-1.32), and SSA/P (1.52, 1.46-1.58). They also applied to different forms of GERD, showing a trend toward stronger associations, that is higher odds ratios, with Barrett's metaplasia or erosive esophagitis than clinical diagnosis of GERD.

CONCLUSION

All types of GERD represent a risk factor for the occurrence of different colon polyps, such as HP, TA, or SSA/P.

APE1-mediated DNA damage repair provides survival advantage for esophageal adenocarcinoma cells in response to acidic bile salts

Chronic Gastroesophageal Reflux Disease (GERD) is the main risk factor for the development of Barrett's esophagus (BE) and its progression to esophageal adenocarcinoma (EAC). Accordingly, EAC cells are subjected to high levels of oxidative stress and subsequent DNA damage. In this study, we investigated the expression and role of Apurinic/apyrimidinic endonuclease 1 (APE1) protein in promoting cancer cell survival by counteracting the lethal effects of acidic bile salts (ABS)-induced DNA damage. Immunohistochemistry analysis of human tissue samples demonstrated overexpression of APE1 in more than half of EACs (70 of 130), as compared to normal esophagus and non-dysplastic BE samples (P < 0.01). To mimic in vivo conditions, we treated in vitro cell models with a cocktail of ABS. The knockdown of endogenous APE1 in EAC FLO-1 cells significantly increased oxidative DNA damage (P < 0.01) and DNA single- and double-strand breaks (P < 0.01), whereas overexpression of APE1 in EAC OE33 cells reversed these effects. Annexin V/PI staining indicated that the APE1 expression in OE33 cells protects against ABS-induced apoptosis. In contrast, knockdown of endogenous APE1 in FLO-1 cells increased apoptosis under the same conditions. Mechanistic investigations indicated that the pro-survival function of APE1 was associated with the regulation of stress response c-Jun N-terminal protein kinase (JNK) and p38 kinases. Pharmacological inhibition of APE1 base excision repair (BER) function decreased cell survival and enhanced activation of JNK and p38 kinases by ABS. Our findings suggest that constitutive overexpression of APE1 in EAC may be an adaptive pro-survival mechanism that protects against the genotoxic lethal effects of bile reflux episodes.

Comparison of the composition of bile acids in bile of patients with adenocarcinoma of the pancreas and benign disease

Bile acids have been implicated in the development of gastrointestinal malignancies. Both the specific nature of individual bile acids and their concentration appear key factors in the carcinogenic potency of bile. Using liquid chromatography mass spectrometry (LC-MS) we performed quantitative profiling of bile extracted directly from the common bile duct in 30 patients (15 patients with pancreatic cancer and 15 patients with benign disease). Separation and detection of bile acids was performed using a 1.7μm particle size reversed-phase C18 LC column at a flow rate of 200μL/min with negative electrospray ionization MS. A significant difference (p=0.018) was seen in the concentration of unconjugated cholic acid in the malignant group (0.643mmol/L) compared to the benign group (0.022mmol/L), with an overall significant difference (p=0.04) seen in the level of total unconjugated bile acids in the malignant group (1.816mmol/L) compared to the benign group (0.069mmol/L). This finding may offer the possibility of both understanding the biology of cancer development in the pancreas, as well as offering a potential diagnostic avenue to explore. However, a larger study is necessary to confirm the alterations in bile acid profiles reported here and explore factors such as diet and microbial populations on the bile acid profiles of these patient groups.

Bile Acids and Cancer: Direct and Environmental-Dependent Effects

Bile acids (BAs) regulate the absorption of fat-soluble vitamins, cholesterol and lipids but have also a key role as singalling molecules and in the modulation of epithelial cell proliferation, gene expression and metabolism. These homeostatic pathways, when disrupted, are able to promote local inflammation, systemic metabolic disorders and, ultimately, cancer. The effect of hydrophobic BAs, in particular, can be linked with cancer in several digestive (mainly oesophagus, stomach, liver, pancreas, biliary tract, colon) and extra-digestive organs (i.e. prostate, breast) through a complex series of mechanisms including direct oxidative stress with DNA damage, apoptosis, epigenetic factors regulating gene expression, reduced/increased expression of nuclear receptors (mainly farnesoid X receptor, FXR) and altered composition of gut microbiota, also acting as a common interface between environmental factors (including diet, lifestyle, exposure to toxics) and the molecular events promoting cancerogenesis. Primary prevention strategies (i.e. changes in dietary habits and lifestyle, reduced exposure to environmental toxics) mainly able to modulate gut microbiota and the epigenome, and the therapeutic use of hydrophilic BAs to counterbalance the negative effects of the more hydrophobic BAs might be, in the near future, part of useful tools for cancer prevention and management.

Cholecystectomy can increase the risk of colorectal cancer: A meta-analysis of 10 cohort studies

OBJECTIVE

This study aimed to elucidate the effects of cholecystectomy on the risk of colorectal cancer (CRC) by conducting a meta-analysis of 10 cohort studies.

METHODS

The eligible cohort studies were selected by searching the PubMed and EMBASE databases from their origination to June 30, 2016, as well as by consulting the reference lists of the selected articles. Two authors individually collected the data from the 10 papers. When the data showed marked heterogeneity, we used a random-effects model to estimate the overall pooled risk; otherwise, a fixed effects model was employed.

RESULTS

The final analysis included ten cohort studies. According to the Newcastle-Ottawa Scale (NOS), nine papers were considered high quality. After the data of these 9 studies were combined, an increased risk of CRC was found among the individuals who had undergone cholecystectomy (risk ratio (RR) 1.22; 95% confidence interval (CI) 1.08-1.38). In addition, we also found a promising increased risk for colon cancer (CC) (RR 1.30, 95% CI 1.07-1.58), but no relationship between cholecystectomy and rectum cancer (RC) (RR 1.09; 95% CI 0.89-1.34) was observed. Additionally, in the sub-group analysis of the tumor location in the colon, a positive risk for ascending colon cancer (ACC) was found (RR 1.18, 95% CI 1.11-1.26). After combining the ACC, transverse colon cancer (TCC), sigmoid colon cancer (SCC) and descending colon cancer (DCC) patients, we found a positive relationship with cholecystectomy (RR 1.18, 95% CI 1.11-1.26). Furthermore, after combining the ACC and DCC patients, we also found a positive relationship with cholecystectomy (RR 1.28; 95% CI 1.11-1.26) in the sub-group analysis. In an additional sub-group analysis of patients from Western countries, there was a positive relationship between cholecystectomy and the risk of CRC (RR 1.20; 95% CI 1.05-1.36). Furthermore, a positive relationship between female gender and CRC was also found (RR 1.17; 95% CI 1.03-1.34). However, there was no relationship between gender and CC or RC. Furthermore, no publication bias was observed, and the sensitivity analysis indicated stable results.

CONCLUSIONS

This meta-analysis of 10 cohort studies revealed that cholecystectomy is associated with an increased risk for CRC, CC and ACC, particularly in Western countries. No relationship between cholecystectomy and RC was observed. There was no relationship between gender and either CC or RC, but a positive relationship between female gender and CRC was observed.

Isolation of six novel 7-oxo- or urso-type secondary bile acid-producing bacteria from rat cecal contents

Understanding the dynamics of secondary bile acid (SBA) formation in the gut by SBA-producing bacteria is important for host health, as SBAs have been shown to affect host pathophysiology and gut microbiota composition. However, our knowledge of SBA producers is limited in light of the diversity of gut microbes. Here, we isolated six novel SBA-producing bacteria from rat cecal contents, all of which were members of known species of gut microbes. Anaerostipes caccae D10, Bacteroides nordii C5, Clostridioides difficile D7, and Clostridium cadaveris G11 were capable of oxidizing cholic acid and chenodeoxycholic acid into 7-oxo-derivatives with varying yields. B. nordii C5 and its type strain JCM 12987^T had the highest molar yield, ∼90%. Clostridium disporicum F4 and Clostridium subterminale C4 epimerized cholic acid into ursocholic acid with yields of ∼85%; the corresponding type strains lacked epimerization activity. Furthermore, although not novel as an SBA producer, Clostridium scindens G10 that produced deoxycholic acid from cholic acid was isolated for the first time from rodents. These findings will contribute to elucidation of SBA formation in the gut.

The role of the microbiome in cancer development and therapy

Answer questions and earn CME/CNE The human body harbors enormous numbers of microbiota that influence cancer susceptibility, in part through their prodigious metabolic capacity and their profound influence on immune cell function. Microbial pathogens drive tumorigenesis in 15% to 20% of cancer cases. Even larger numbers of malignancies are associated with an altered composition of commensal microbiota (dysbiosis) based on microbiome studies using metagenomic sequencing. Although association studies cannot distinguish whether changes in microbiota are causes or effects of cancer, a causative role is supported by rigorously controlled preclinical studies using gnotobiotic mouse models colonized with one or more specific bacteria. These studies demonstrate that microbiota can alter cancer susceptibility and progression by diverse mechanisms, such as modulating inflammation, inducing DNA damage, and producing metabolites involved in oncogenesis or tumor suppression. Evidence is emerging that microbiota can be manipulated for improving cancer treatment. By incorporating probiotics as adjuvants for checkpoint immunotherapy or by designing small molecules that target microbial enzymes, microbiota can be harnessed to improve cancer care. CA Cancer J Clin 2017;67:326-344. © 2017 American Cancer Society.

Effect of Liver Disease on Hepatic Transporter Expression and Function

Liver disease can alter the disposition of xenobiotics and endogenous substances. Regulatory agencies such as the Food and Drug Administration and the European Medicines Evaluation Agency recommend, if possible, studying the effect of liver disease on drugs under development to guide specific dose recommendations in these patients. Although extensive research has been conducted to characterize the effect of liver disease on drug-metabolizing enzymes, emerging data have implicated that the expression and function of hepatobiliary transport proteins also are altered in liver disease. This review summarizes recent developments in the field, which may have implications for understanding altered disposition, safety, and efficacy of new and existing drugs. A brief review of liver physiology and hepatic transporter localization/function is provided. Then, the expression and function of hepatic transporters in cholestasis, hepatitis C infection, hepatocellular carcinoma, human immunodeficiency virus infection, nonalcoholic fatty liver disease and nonalcoholic steatohepatitis, and primary biliary cirrhosis are reviewed. In the absence of clinical data, nonclinical information in animal models is presented. This review aims to advance the understanding of altered expression and function of hepatic transporters in liver disease and the implications of such changes on drug disposition.

Sex-dependent effects on gut microbiota regulate hepatic carcinogenic outcomes

Emerging evidence points to a strong association between sex and gut microbiota, bile acids (BAs), and gastrointestinal cancers. Here, we investigated the mechanistic link between microbiota and hepatocellular carcinogenesis using a streptozotocin-high fat diet (STZ-HFD) induced nonalcoholic steatohepatitis-hepatocellular carcinoma (NASH-HCC) murine model and compared results for both sexes. STZ-HFD feeding induced a much higher incidence of HCC in male mice with substantially increased intrahepatic retention of hydrophobic BAs and decreased hepatic expression of tumor-suppressive microRNAs. Metagenomic analysis showed differences in gut microbiota involved in BA metabolism between normal male and female mice, and such differences were amplified when mice of both sexes were exposed to STZ-HFD. Treating STZ-HFD male mice with 2% cholestyramine led to significant improvement of hepatic BA retention, tumor-suppressive microRNA expressions, microbial gut communities, and prevention of HCC. Additionally the sex-dependent differences in BA profiles in the murine model can be correlated to the differential BA profiles between men and women during the development of HCC. These results uncover distinct male and female profiles for gut microbiota, BAs, and microRNAs that may contribute to sex-based disparity in liver carcinogenesis, and suggest new possibilities for preventing and controlling human obesity-related gastrointestinal cancers that often exhibit sex differences.

Co-infections with liver fluke and Helicobacter species: A paradigm change in pathogenesis of opisthorchiasis and cholangiocarcinoma?

Infection with the fish-borne liver fluke Opisthorchis viverrini is classified by the International Agency for Research on Cancer as a Group 1 carcinogen: definitely carcinogenic in humans. Cofactors likely contribute to bile duct cancer (cholangiocarcinoma) caused by this infection. Here we review recent findings that address the role of liver fluke associated H. pylori in hepatobiliary disease and malignancy. We hypothesize that co-infection by O. viverrini and the bacillus Helicobacter pylori is central of liver fluke infection associated cholangiocarcinoma.

Bile acid: a potential inducer of colon cancer stem cells

Background

Although the unconjugated secondary bile acids, specifically deoxycholic acid (DCA) and lithocholic acid (LCA), are considered to be risk factors for colorectal cancer, the precise mechanism(s) by which they regulate carcinogenesis is poorly understood. We hypothesize that the cytotoxic bile acids may promote stemness in colonic epithelial cells leading to generation of cancer stem cells (CSCs) that play a role in the development and progression of colon cancer.

Methods

Normal human colonic epithelial cells (HCoEpiC) were used to study bile acid DCA/LCA-mediated induction of CSCs. The expression of CSC markers was measured by real-time qPCR. Flow cytometry was used to isolate CSCs. T-cell factor/lymphoid-enhancing factor (TCF/LEF) luciferase assay was employed to examine the transcriptional activity of β-catenin. Downregulation of muscarinic 3 receptor (M3R) was achieved through transfection of corresponding siRNA.

Results

We found DCA/LCA to induce CSCs in normal human colonic epithelial cells, as evidenced by the increased proportion of CSCs, elevated levels of several CSC markers, as well as a number of epithelial–mesenchymal transition markers together with increased colonosphere formation, drug exclusion, ABCB1 and ABCG2 expression, and induction of M3R, p-EGFR, matrix metallopeptidases, and c-Myc. Inhibition of M3R signaling greatly suppressed DCA/LCA induction of the CSC marker ALDHA1 and also c-Myc mRNA expression as well as transcriptional activation of TCF/LEF.

Conclusions

Our results suggest that bile acids, specifically DCA and LCA, induce cancer stemness in colonic epithelial cells by modulating M3R and Wnt/β-catenin signaling and thus could be considered promoters of colon cancer.

Fecal Metabolome in Hmga1 Transgenic Mice with Polyposis: Evidence for Potential Screen for Early Detection of Precursor Lesions in Colorectal Cancer

Because colorectal cancer (CRC) remains a leading cause of cancer mortality worldwide, more accessible screening tests are urgently needed to identify early stage lesions. We hypothesized that highly sensitive, metabolic profile analysis of stool samples will identify metabolites associated with early stage lesions and could serve as a noninvasive screening test. We therefore applied traveling wave ion mobility mass spectrometry (TWIMMS) coupled with ultraperformance liquid chromatography (UPLC) to investigate metabolic aberrations in stool samples in a transgenic model of premalignant polyposis aberrantly expressing the gene encoding the high mobility group A (Hmga1) chromatin remodeling protein. Here, we report for the first time that the fecal metabolome of Hmga1 mice is distinct from that of control mice and includes metabolites previously identified in human CRC. Significant alterations were observed in fatty acid metabolites and metabolites associated with bile acids (hypoxanthine xanthine, taurine) in Hmga1 mice compared to controls. Surprisingly, a marked increase in the levels of distinctive short, arginine-enriched, tetra-peptide fragments was observed in the transgenic mice. Together these findings suggest that specific metabolites are associated with Hmga1-induced polyposis and abnormal proliferation in intestinal epithelium. Although further studies are needed, these data provide a compelling rationale to develop fecal metabolomic analysis as a noninvasive screening tool to detect early precursor lesions to CRC in humans.

Shifts in the Fecal Microbiota Associated with Adenomatous Polyps

BACKGROUND

Adenomatous polyps are the most common precursor to colorectal cancer, the second leading cause of cancer-related death in the United States. We sought to learn more about early events of carcinogenesis by investigating shifts in the gut microbiota of patients with adenomas.

METHODS

We analyzed 16S rRNA gene sequences from the fecal microbiota of patients with adenomas (n = 233) and without (n = 547).

RESULTS

Multiple taxa were significantly more abundant in patients with adenomas, including Bilophila, Desulfovibrio, proinflammatory bacteria in the genus Mogibacterium, and multiple Bacteroidetes species. Patients without adenomas had greater abundances of Veillonella, Firmicutes (Order Clostridia), and Actinobacteria (family Bifidobacteriales). Our findings were consistent with previously reported shifts in the gut microbiota of colorectal cancer patients. Importantly, the altered adenoma profile is predicted to increase primary and secondary bile acid production, as well as starch, sucrose, lipid, and phenylpropanoid metabolism.

CONCLUSIONS

These data hint that increased sugar, protein, and lipid metabolism along with increased bile acid production could promote a colonic environment that supports the growth of bile-tolerant microbes such as Bilophilia and Desulfovibrio In turn, these microbes may produce genotoxic or inflammatory metabolites such as H₂S and secondary bile acids, which could play a role in catalyzing adenoma development and eventually colorectal cancer.

IMPACT

This study suggests a plausible biological mechanism to explain the links between shifts in the microbiota and colorectal cancer. This represents a first step toward resolving the complex interactions that shape the adenoma-carcinoma sequence of colorectal cancer and may facilitate personalized therapeutics focused on the microbiota. Cancer Epidemiol Biomarkers Prev; 26(1); 85-94. ©2016 AACR.

Cranberry proanthocyanidins inhibit esophageal adenocarcinoma in vitro and in vivo through pleiotropic cell death induction and PI3K/AKT/mTOR inactivation

Cranberries are rich in bioactive constituents known to improve urinary tract health and more recent evidence supports cranberries possess cancer inhibitory properties. However, mechanisms of cancer inhibition by cranberries remain to be elucidated, particularly in vivo. Properties of a purified cranberry-derived proanthocyanidin extract (C-PAC) were investigated utilizing acid-sensitive and acid-resistant human esophageal adenocarcinoma (EAC) cell lines and esophageal tumor xenografts in athymic NU/NU mice. C-PAC induced caspase-independent cell death mainly via autophagy and low levels of apoptosis in acid-sensitive JHAD1 and OE33 cells, but resulted in cellular necrosis in acid-resistant OE19 cells. Similarly, C-PAC induced necrosis in JHAD1 cells pushed to acid-resistance via repeated exposures to an acidified bile cocktail. C-PAC associated cell death involved PI3K/AKT/mTOR inactivation, pro-apoptotic protein induction (BAX, BAK1, deamidated BCL-xL, Cytochrome C, PARP), modulation of MAPKs (P-P38/P-JNK) and G_2-M cell cycle arrest in vitro. Importantly, oral delivery of C-PAC significantly inhibited OE19 tumor xenograft growth via modulation of AKT/mTOR/MAPK signaling and induction of the autophagic form of LC3B supporting in vivo efficacy against EAC for the first time. C-PAC is a potent inducer of EAC cell death and is efficacious in vivo at non-toxic behaviorally achievable concentrations, holding promise for preventive or therapeutic interventions in cohorts at increased risk for EAC, a rapidly rising and extremely deadly malignancy.

The association between biliary tract inflammation and risk of digestive system cancers: A population-based cohort study

The relationship between biliary tract inflammation (BTI) and digestive system cancers is unclear. This study aimed to evaluate the association between BTI and the risks of digestive system cancers.Using the Taiwan National Health Insurance claims data, information on a cohort of patients diagnosed with BTI (n = 4398) between 2000 and 2009 was collected. A comparison cohort of sex-, age-, and index year-matched persons without BTI (n = 17,592) was selected from the same database. The disease was defined by the ICD-9-CM. Both cohorts were followed until the end of 2010 and incidences of digestive system cancers were calculated.The results revealed an increase in adjusted hazard ratio (aHR) of biliary tract cancer (24.45; 95% confidence interval [CI]: 9.20-65.02), primary liver cancer (1.53; 95% CI: 1.07-2.18), and pancreatic cancer (3.10; 95% CI: 1.20-8.03) in patients with both gallbladder and BTI. The aHR of stomach cancer was also found to be increased (2.73; 95% CI: 1.28-5.81) in patients with gallbladder inflammation only. There were no differences in esophageal cancer (aHR: 0.82; 95% CI: 0.23-2.87) and colorectal cancer (aHR: 0.92; 95% CI: 0.59-1.45). The aHR for digestive system cancers increased by 3.66 times (95% CI: 2.50-5.35) and 12.20 times (95% CI: 8.66-17.17) in BTI visits frequency averaged 2 to 4 visits per year and frequency averaged ≥5 visits per year, respectively.Patients with BTI have significantly higher risk of digestive system cancers, particularly biliary tract, pancreatic, and primary liver cancers, compared with those who are without it.

Dysregulated hepatic bile acids collaboratively promote liver carcinogenesis

Dysregulated bile acids (BAs) are closely associated with liver diseases and attributed to altered gut microbiota. Here, we show that the intrahepatic retention of hydrophobic BAs including deoxycholate (DCA), taurocholate (TCA), taurochenodeoxycholate (TCDCA), and taurolithocholate (TLCA) were substantially increased in a streptozotocin and high fat diet (HFD) induced nonalcoholic steatohepatitis-hepatocellular carcinoma (NASH-HCC) mouse model. Additionally chronic HFD-fed mice spontaneously developed liver tumors with significantly increased hepatic BA levels. Enhancing intestinal excretion of hydrophobic BAs in the NASH-HCC model mice by a 2% cholestyramine feeding significantly prevented HCC development. The gut microbiota alterations were closely correlated with altered BA levels in liver and feces. HFD-induced inflammation inhibited key BA transporters, resulting in sustained increases in intrahepatic BA concentrations. Our study also showed a significantly increased cell proliferation in BA treated normal human hepatic cell lines and a down-regulated expression of tumor suppressor gene CEBPα in TCDCA treated HepG2 cell line, suggesting that several hydrophobic BAs may collaboratively promote liver carcinogenesis.

FXR agonists enhance the sensitivity of biliary tract cancer cells to cisplatin via SHP dependent inhibition of Bcl-xL expression

Chemoresistance is common in patients with biliary tract cancer (BTC) including gallbladder cancer (GBC) and cholangiocarcinoma (CC). Therefore, it is necessary to identify effective chemotherapeutic agents for BTC. In the present study, we for the first time tested the effect of farnesoid X receptor (FXR) agonists GW4064 and CDCA (chenodeoxycholic acid) in combination with cisplatin (CDDP) on increasing the chemosensitivity in BTC. Our results show that co-treatment of CDDP with FXR agonists remarkably enhance chemosensitivity of BTC cells. Mechanistically, we found that activation of FXR induced expression of small heterodimer partner (SHP), which in turn inhibited signal transducer and activator of transcription 3 (STAT3) phosphorylation and resulted in down-regulation of Bcl-xL expression in BTC cells, leading to increased susceptibility to CDDP. Moreover, the experiments on tumor-bearing mice showed that GW4064/CDDP co-treatment inhibited the tumor growth in vivo by up-regulating SHP expression and down-regulating STAT3 phosphorylation. These results suggest CDDP in combination with FXR agonists could be a potential new therapeutic strategy for BTC.

Metabolomics and metabolic pathway networks from human colorectal cancers, adjacent mucosa, and stool

Background

Colorectal cancers (CRC) are associated with perturbations in cellular amino acids, nucleotides, pentose-phosphate pathway carbohydrates, and glycolytic, gluconeogenic, and tricarboxylic acid intermediates. A non-targeted global metabolome approach was utilized for exploring human CRC, adjacent mucosa, and stool. In this pilot study, we identified metabolite profile differences between CRC and adjacent mucosa from patients undergoing colonic resection. Metabolic pathway analyses further revealed relationships between complex networks of metabolites.

Methods

Seventeen CRC patients participated in this pilot study and provided CRC, adjacent mucosa ~10 cm proximal to the tumor, and stool. Metabolomes were analyzed by gas chromatography-mass spectrometry (GC/MS) and ultra-performance liquid chromatography-mass spectrometry (UPLC-MS/MS). All of the library standard identifications were confirmed and further analyzed via MetaboLync^TM for metabolic network interactions.

Results

There were a total of 728 distinct metabolites identified from colonic tissue and stool matrices. Nineteen metabolites significantly distinguished CRC from adjacent mucosa in our patient-matched cohort. Glucose-6-phosphate and fructose-6-phosphate demonstrated 0.64-fold and 0.75-fold lower expression in CRC compared to mucosa, respectively, whereas isobar: betaine aldehyde, N-methyldiethanolamine, and adenylosuccinate had 2.68-fold and 1.88-fold higher relative abundance in CRC. Eleven of the 19 metabolites had not previously been reported for CRC relevance. Metabolic pathway analysis revealed significant perturbations of short-chain fatty acid metabolism, fructose, mannose, and galactose metabolism, and glycolytic, gluconeogenic, and pyruvate metabolism. In comparison to the 500 stool metabolites identified from human CRC patients, only 215 of those stool metabolites were also detected in tissue. This CRC and stool metabolome investigation identified novel metabolites that may serve as key small molecules in CRC pathogenesis, confirmed the results from previously reported CRC metabolome studies, and showed networks for metabolic pathway aberrations. In addition, we found differences between the CRC and stool metabolomes.

Conclusions

Stool metabolite profiles were limited for direct associations with CRC and adjacent mucosa, yet metabolic pathways were conserved across both matrices. Larger patient-matched CRC, adjacent non-cancerous colonic mucosa, and stool cohort studies for metabolite profiling are needed to validate these small molecule differences and metabolic pathway aberrations for clinical application to CRC control, treatment, and prevention.

Electronic supplementary material

The online version of this article (doi:10.1186/s40170-016-0151-y) contains supplementary material, which is available to authorized users.

Diet and Colorectal Cancer Risk in Asia--a Systematic Review

Diet is one of the major factors that can exert a majorly influence on colorectal cancer risk. This systematic review aimed to find correlations between various diet types, food or nutrients and colorectal cancer risk among Asian populations. Search limitations included Asian populations residing in Asia, being published from the year 2008 till present, and written in the English language. A total of 16 articles were included in this systematic review. We found that red meats, processed meats, preserved foods, saturated/animal fats, cholesterol, high sugar foods, spicy foods, tubers or refined carbohydrates have been found by most studies to have a positive association with colorectal cancer risk. Inversely, calcium/dairy foods, vitamin D, general vegetable/fruit/fiber consumption, cruciferous vegetables, soy bean/soy products, selenium, vitamins C,E and B12, lycophene, alpha-carotene, beta-carotene, folic acid and many other vitamins and minerals play a protective role against colorectal cancer risk. Associations of fish and seafood consumption with colorectal cancer risk are still inconclusive due to many varying findings, and require further more detailed studies to pinpoint the actual correlation. There is either a positive or no association for total meat consumption or white meats, however their influence is not as strong as with red and processed meats.

Deoxycholic acid mediates non-canonical EGFR-MAPK activation through the induction of calcium signaling in colon cancer cells

Obesity and a western diet have been linked to high levels of bile acids and the development of colon cancer. Specifically, increased levels of the bile acid deoxycholic acid (DCA), an established tumor promoter, has been shown to correlate with increased development of colorectal adenomas and progression to carcinoma. Herein we investigate the mechanism by which DCA leads to EGFR-MAPK activation, a candidate mechanism by which DCA may promote colorectal tumorigenesis. DCA treated colon cancer cells exhibited strong and prolonged activation of ERK1/2 when compared to EGF treatment alone. We also showed that DCA treatment prevents EGFR degradation as opposed to the canonical EGFR recycling observed with EGF treatment. Moreover, the combination of DCA and EGF treatment displayed synergistic activity, suggesting DCA activates MAPK signaling in a non-canonical manner. Further evaluation showed that DCA treatment increased intracellular calcium levels and CAMKII phosphorylation, and that blocking calcium with BAPTA-AM abrogated MAPK activation induced by DCA, but not by EGF. Finally we showed that DCA-induced CAMKII leads to MAPK activation through the recruitment of c-Src. Taken together, we demonstrated that DCA regulates MAPK activation through calcium signaling, an alternative mechanism not previously recognized in human colon cancer cells. Importantly, this mechanism allows for EGFR to escape degradation and thus achieve a constitutively active state, which may explain its tumor promoting effects.

Diet, microbiota, and dysbiosis: a 'recipe' for colorectal cancer

The food we consume feeds not only us, but also a vast and diverse community of microbiota within our gastrointestinal tract. In a process of symbiotic co-evolution, the gut microbiota became essential for the maintenance of the health and integrity of our colon. The advent of next-generation DNA sequencing technology and metabolic profiling have, in the recent years, revealed the remarkable complexity of microbial diversity and function, and that the microbiota produce a wide variety of bioactive products that are not only active at the mucosal surface, but also absorbed and circulated throughout the body, influencing distant organ health and function. As a result, several microbiota compositional patterns and their associations with both health and disease states have been identified. Importantly, a disturbed microbiota-host relationship, termed dysbiosis, is now recognized to be the root cause for a growing list of diseases, including colorectal cancer (CRC). There is mounting in vitro and in vivo evidence to suggest that diet selects for the microbiota composition and several health promoting and deleterious effects of diet are, in fact, mediated by the microbiota. Recent findings of the feasibility of dietary fiber to boost the colonic microbial synthesis of anti-proliferative and counter carcinogenic metabolites, particularly butyrate, underscores the prerequisite of dietary modification as a key measure to curb the pandemic of CRC in westernized countries. Better understanding of the diet-microbiota interplay and large-scale studies to evaluate the efficacy of dietary modification and gut microbiota modulation in reversing dysbiosis and restoring health could offer novel preventative and/or therapeutic strategies against westernized diseases, which are now considered the chief threat to public health.

Increased Risk of Pancreatic Cancer Related to Gallstones and Cholecystectomy: A Systematic Review and Meta-Analysis

To investigate the potential roles of gallstones and cholecystectomy in pancreatic carcinogenesis, we performed the first meta-analysis of all currently published studies by pooling relative risks (RRs) with 95% confidence intervals (95% CIs). Stratified analysis by ethnicity, study design, and common adjusted factors were also conducted. Individuals with a history of gallstones and cholecystectomy were at increased risk of pancreatic cancer (RR, 1.39; 95% CI, 1.28-1.52; P < 0.001). Gallstones and cholecystectomy were also associated with an elevated risk of pancreatic cancer, respectively (for gallstones: RR, 1.70; 95% CI, 1.30-2.21; P < 0.001; for cholecystectomy: RR, 1.31; 95% CI, 1.19-1.43; P < 0.001). The positive association is observed among not only the Asian population but also whites. The pooled findings were further confirmed by sensitivity analysis and stratified analyses in case-control and cohort studies. Stratified analyses by different adjusted factors further showed that the increased risk of pancreatic cancer was independent of confounders including diabetes, obesity, smoking, and follow-up years of postcholecystectomy. A history of gallstones and cholecystectomy is a robust risk factor for pancreatic cancer. Gallstone disease or cholecystectomy alone is also an independent risk factor for pancreatic carcinogenesis.

Gastrointestinal Microbiota and Colon Cancer

The human gut microbiota plays a major role in the development and maintenance of good health. Many recent studies have attempted to define links between microbiota residents, their function and the development of colorectal cancer (CRC). Gut microbiota drive the development of inflammation within the colon and such inflammation is implicated in colonic neoplastic development. Although the precise mechanisms through which the microbiota is involved in cancer development remain elusive, the message is clear: the microbiota contributes to cancer risk by influencing a number of key host processes. It is also recognized that we have the ability to influence the role of the gut microbiota by considering our nutritional intake. We have always known that 'we are what we eat' but it is also true that 'they (our gut microbiota) are what we eat'. We therefore have a huge opportunity to positively influence our health through microbial manipulation. There is now a clear need to move past defining the constituents of the gastrointestinal microbiota and to focus more on understanding the functional capabilities of the resident microbial community and how this impacts on host health. One such emerging concept is the development of microbial biofilms which can form in the gut in conjunction with CRC tissue. By better understanding of the interaction between the host and its resident microbiota, in the context of health and cancer development, we will open new therapeutic and diagnostic opportunities for reducing the CRC global health burden.

An Integrated Outlook on the Metagenome and Metabolome of Intestinal Diseases

Recently, metagenomics and metabolomics are the two most rapidly advancing “omics” technologies. Metagenomics seeks to characterize the composition of microbial communities, their operations, and their dynamically co-evolving relationships with the habitats they occupy, whereas metabolomics studies unique chemical endpoints (metabolites) that specific cellular processes leave behind. Remarkable progress in DNA sequencing and mass spectrometry technologies has enabled the comprehensive collection of information on the gut microbiome and its metabolome in order to assess the influence of the gut microbiota on host physiology on a whole-systems level. Our gut microbiota, which consists of prokaryotic cells together with its metabolites, creates a unique gut ecosystem together with the host eukaryotic cells. In this review, we will highlight the detailed relationships between gut microbiota and its metabolites on host health and the pathogenesis of various intestinal diseases such as inflammatory bowel disease and colorectal cancer. Therapeutic interventions such as probiotic and prebiotic administrations and fecal microbiota transplantations will also be discussed. We would like to promote this unique biology-wide approach of incorporating metagenome and metabolome information as we believe that this can help us understand the intricate interplay between gut microbiota and host metabolism to a greater extent. This novel integration of microbiome, metatranscriptome, and metabolome information will help us have an improved holistic understanding of the complex mammalian superorganism, thereby allowing us to gain new and unprecedented insights to providing exciting novel therapeutic approaches for optimal intestinal health.

Right colon carcinoma infiltrating the alimentary limb in a patient with biliopancreatic diversion

Biliopancreatic diversion (BPD) has excellent results, with the average patient losing 60% to 80% of the excess weight in the first 2 years. However, the BPD works by malabsorption and malabsorptive problems may be experienced with the operation. Therefore, monitoring is necessary for life. In the recent literature there is some debate over the possibility that this technique can increase the risk of colon cancer secondary to the action of the unabsorbed food and bile acid on colonic mucosa. We report the case of a 42-year-old patient with a previous bariatric surgery (BPD with 50 cm common channel; 300 cm alimentary limb) who developed a very aggressive right colon cancer 6 years after the operation. We also review our series of 330 patients operated on during a 14-year period to try to answer if there is any relationship between BPD and colon cancer.

Correlation between Barrett's esophagus and colorectal polyps

AIM: To explore the correlation between Barrett's esophagus and colorectal polyps.

METHODS: A total of 41 patients with Barrett's esophagus and 176 controls were enrolled in the study. The incidence, pathological type and location of colorectal polyps were compared.

RESULTS: The incidence of polyps in patients with Barrett's esophagus was 41.5%, which was significantly higher than that of the control group (25.6%) (P = 0.042). The incidence of adenomatous polyps in patients with Barrett's esophagus was also significantly higher than that of the control group (P = 0.008), although there was no significant difference in the incidence of hyperplastic polyps and inflammatory polyps. The location of colorectal polyps showed no significant difference between the two groups. Logistic multivariate regression analysis revealed that Barrett's esophagus was an independent risk factor for colorectal polyps (OR = 2.397, 95%CI: 1.146-5.013, P = 0.020).

CONCLUSION: Patients with Barrett's esophagus have a higher incidence of colorectal polyps. Therefore, the screening and surveillance of colorectal polyps should be enhanced in patients with Barrett's esophagus.

The role of bile acids in reducing the metabolic complications of obesity after bariatric surgery: a systematic review

BACKGROUND

Bariatric surgery is currently the most efficacious treatment for obesity and its associated metabolic co-morbidities, such as diabetes. The metabolic improvements occur through both weight-dependent and weight-independent mechanisms. Bile acids (BAs) have emerged as key signalling molecules that have a central role in modulating many of the physiological effects seen after bariatric surgery. This systematic review assesses the evidence from both human and animal studies for the role of BAs in reducing the metabolic complications of obesity following bariatric surgery.

METHODS

We conducted a systematic search of Medline and Embase databases to identify all articles investigating the role of BAs in mediating the metabolic changes observed following bariatric surgery in both animal and human studies. Boolean logic was used with relevant search terms, including the following MeSH terms: 'bile acids and salts', 'bariatric surgery', 'metabolic surgery', 'gastrointestinal tract/surgery' and 'obesity/surgery'.

RESULTS

Following database searches (n=1197), inclusion from bibliography searches (n=2) and de-duplication (n=197), 1002 search results were returned. Of these, 132 articles were selected for full-text review, of which 38 articles were deemed relevant and included in the review. The findings support the effects of BAs on satiety, lipid and cholesterol metabolism, incretins and glucose homoeostasis, energy metabolism, gut microbiota and endoplasmic reticulum stress following bariatric surgery. Many of these metabolic effects are modulated through the BA receptors FXR and TGR5. We also explore a possible link between BAs and carcinogenesis following bariatric surgery.

CONCLUSIONS

Overall there is good evidence to support the role of BAs in the metabolic effects of bariatric surgery through the above mechanisms. BAs could serve as a novel therapeutic pharmacological target for the treatment of obesity and its associated co-morbidities.